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FatCat_99
02-01-2010, 11:33 AM
Hi,
we have some very strange performing Spits MkV in game, in this thread you can provide info about RL SPit MkV perormance and suggest how should MkV perform in game.

My main interest is in finding out what would be representative boost for different variants and Spit turn rates.

FC

DKoor
02-01-2010, 11:43 AM
http://forums.ubi.com/images/smilies/25.gif

M_Gunz
02-01-2010, 11:59 AM
You will be shown both lemons and cherries, BE SURE! http://forums.ubi.com/images/smilies/88.gif

I would like to check, you know that 1941 SpitVB is really middle-1942?
Also that when Oleg chose data he had not only engines but specific props used?

Some data you get will be best(or maye worst) of one configuration mixed with best(/worst) of others.

Doe Oleg not have data directly from British museum people? I know he visited prior to announcing that
the first SOW title would be Battle of Britain and from reports he got much data at least of 1940.

I hope you get and use all authenticated data or the forums will be revisionist feeding frenzy, also BE SURE!

Never will everyone be happy, no matter how you choose. With luck, maybe half will.

Sillius_Sodus
02-01-2010, 12:06 PM
Which version of the Spit V did the VVS get during the war, the '41 version or the '42?

This could have a bearing on any non-Eastern Front scenarios flown in the non-modded game.

GBrutus
02-01-2010, 12:14 PM
Originally posted by M_Gunz:
I hope you get and use all authenticated data or the forums will be revisionist feeding frenzy, also BE SURE!

+1

thefruitbat
02-01-2010, 12:16 PM
I've been trying to make some sense out of the spit mkV for a little while now, and while the only performance data i know, is on spitfire performance, which i'm sure you know of already, this is what i have been able to find out recently about engines used, although i'm still looking for more info to fill in a few gaps.

Vb feb 1941, with merlin 45

Vc Oct 1941 with merlin 45

Merlin 46 also used in both, which is the high altitude version, don't know when introduced.

merlin 45M cropped for low level, can't seem to find exact date when either.

April 1942, Merlin 50 introduced, which is essentially the same as a merlin 45, only has the SU carb, which finally cures sustained neg g manuvers, as oppossed to miss Shillings Orifice, which was fitted from march '41 onwards as standard, which partially cured the problem (same diff between merlin 45m/50m only low level version again)

Really not an easy plane to make sense off, also seen ref to merlin 55m, although can't find any info on it, although it must of been one of the low level cropped engines.

Not a great deal of help i know, but there you go.

FatCat_99
02-01-2010, 12:25 PM
Originally posted by Sillius_Sodus:
Which version of the Spit V did the VVS get during the war, the '41 version or the '42?

This could have a bearing on any non-Eastern Front scenarios flown in the non-modded game.
We have these MkV ingame

SpitfireMkVb
SpitfireMkVbCLP
SpitfireMkVbLF
SpitfireMkVbLFCLP
SpitfireMkVc
SpitfireMkVc4xH

So we have possibility to have them at different boosts and if their 3d model is the same we can add new variant if that is historically justified.

FC

thefruitbat
02-01-2010, 12:30 PM
A Vc without the trop filter would be nice, since they served in numbers in the ETO as well as the med.

same model as the Vb can be used, just with c wing ammo loads.

GBrutus
02-01-2010, 12:35 PM
Originally posted by thefruitbat:
A Vc without the trop filter would be nice, since they served in numbers in the ETO as well as the med.

same model as the Vb can be used, just with c wing ammo loads.

There would have to be some 3D work for this, I'm afraid. You could borrow the C wing from the Mk.IX but you would end up with an extra radiator too.

thefruitbat
02-01-2010, 12:45 PM
What was the external diference between the b and c wing on the spitV, i thought it was all internal?

as to boosts, merlin 45 started out as 12lbs, melin 50 limited to 16lbs, and the merlin 50m was cleared for 18lbs i belive.

GBrutus
02-01-2010, 01:08 PM
The size and positioning of the cannon blisters was the main difference externally. Have a look at this link...

http://spitfiresite.com/refere...pitfire-wings-01.htm (http://spitfiresite.com/reference/variants-technology/2008/04/spitfire-wings-01.htm)

GBrutus
02-01-2010, 01:11 PM
Actually I could have found a better link as there's no photos on that page. I'll dig around for something better...

thefruitbat
02-01-2010, 01:15 PM
my bad then! cheers for the link, not stumbled across that one before http://forums.ubi.com/images/smilies/25.gif all links welcome, lol!

horseback
02-01-2010, 01:23 PM
Biggest visual difference between Vb and Vc wings were the 'nubs' for the missing cannon outboard of the cannon barrels.

Obviously, the cannon breech bulges were also somewhat different; the first versions were the wide two-cannon bulges that remind me of a rounded off Norman shield, as opposed to the more teardrop-like shape of the Vb's cannon breech bulge. The next version had a long narrow single gun bulge pointed at both ends for single cannon wings and two narrow bulges for the fairly rare two-cannon wings.

Also, as more became known about streamlining and so on, later Mk Vs would be retrofitted with six-stack exhausts like those on the Seafires or Spitfire Mk IXs & VIIIs.

The Mk V was in almost constant use from 1941 onwards, and was often a work in progress. Early versions might have been more likely to have the rounder DeHaviland type prop spinner, an externally mounted armorglass windscreen, and a Vb type wing; later versions would be marked by the pointy prop spinner denoting the compressed wooden props, an internal armorglass windscreen, and 'c' type wing.

For visual clues to types and models, you really should look into (particularly British) publications aimed at the scale modeling market. These are often full of visual detail, drawings, paintings and photographs.

cheers

horseback

GBrutus
02-01-2010, 01:24 PM
I was trying to find another link but I had my 2 year old hanging from my neck which is a bit of a distraction. Another thing to note is that there are other subtle diffrences btween the Vb and Vc such as the horn balances on the elevators. That site I linked has quite a few articles on Spifire variants and I've found it a very useful resource. I'd like to see a late war Vc in game myself btw, I wasn't meaning to be nerdy about this stuff.

JtD
02-01-2010, 01:26 PM
The B wing also had no .50 stubs.

The Soviets got 9lbs for the most part, at least up to 1943 they had Vc's running on low boost. I'm not sure they ever went up.
---
My major question regarding the Merlin45 etc., they were cleared for 12lb boost on take off. Did this coincide with the clearance for 16lb boost WEP or was that separate? If so, when and what was the deal? What power was generated at 12lb boost? Has anyone got a power chart of the Merlin 45, 46, 47?

Has anyone got loading plans for the various versions of the V series?

I'm also looking for a wind tunnel based drag polar of a V, preferably a b version.

The c wing had provisions for external loads, 2x250lbs of bombs. Were bomb racks ever fitted to the b wing? I've read contradicting statements, but haven't seen original documents.

I know we have a couple of folks around who know a lot about the Spitfire, would be great if you could save me some lengthy research. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

thefruitbat
02-01-2010, 01:39 PM
the Vc in game is a mess anyway, the wings are far to low when looking out of the cockpit, although this has been corrected in various mod packs, would be nice if it was in stock to.

Vb

http://i7.photobucket.com/albums/y290/thefruitbat1/grab0000-21.jpg

Vc

http://i7.photobucket.com/albums/y290/thefruitbat1/grab0001-18.jpg

wouldn't putting the nose of the Vb on the existing Vc, or the existing Vc wings on a spitVb be the easist way of geeting a proper late Vc, anyway?

no need to make anything new, we have all the components already, just not together.

GBrutus
02-01-2010, 01:56 PM
The Shuttleworth Collection has a lovely Spitfire Vc...

http://i2.photobucket.com/albums/y2/Grisha7/06394122.jpg

Note this one has a de Havilland prop.

GBrutus
02-01-2010, 02:06 PM
@ Fruitbat, the Vb and Vc are completely different 3D models in game so swapping the meshes wouldn't be ideal. Best way, IMO, would be to use the Vc/seafire model but there would still be 3D work required which I think FatCat wants to avoid.

BillSwagger
02-01-2010, 02:43 PM
Originally posted by FatCat_99:
Hi,
we have some very strange performing Spits MkV in game

strange how?

The rule on spits is that generally, the bigger the engine, the better the rate, but the wider the radius.

Cannons usually imply more weight, so that should also decrease turn performance. I just wondered if empty weight of cannon wielding Spits was more or less than that of a Spit with 303s.

I saw on another forum where a person had posted Russian tests figures. There were some interesting figures, most of which put the SpitV at the top of turn rate, measured in time it takes to make 1 complete circle (17-18 seconds). Whats difficult about these studies is that there is no indication of radius, but i have to guess that's a best sustained figure.


Bill

Gammelpreusse
02-01-2010, 03:04 PM
Originally posted by JtD:
The B wing also had no .50 stubs.


B*llocks, watch more closely!

http://le.one.free.fr/images/Bwing.jpg

GBrutus
02-01-2010, 03:19 PM
Proof that .50s can own an Imperial Star Destroyer. Awesome.

Kurfurst__
02-01-2010, 04:30 PM
Originally posted by BillSwagger:
I saw on another forum where a person had posted Russian tests figures. There were some interesting figures, most of which put the SpitV at the top of turn rate, measured in time it takes to make 1 complete circle (17-18 seconds). Whats difficult about these studies is that there is no indication of radius, but i have to guess that's a best sustained figure.

Bill

Recalling from memory, the Soviet book gave a turn radius figure of 235 meter for the "Spitfire", but did not specify wheter it was Mk V or IXLF...

FatCat_99
02-01-2010, 05:20 PM
Originally posted by BillSwagger:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FatCat_99:
Hi,
we have some very strange performing Spits MkV in game

strange how?

The rule on spits is that generally, the bigger the engine, the better the rate, but the wider the radius.

I saw on another forum where a person had posted Russian tests figures. There were some interesting figures, most of which put the SpitV at the top of turn rate, measured in time it takes to make 1 complete circle (17-18 seconds). Whats difficult about these studies is that there is no indication of radius, but i have to guess that's a best sustained figure.
</div></BLOCKQUOTE>Strange because current Spits MkV doesn't match any RL test that I know, in general they are too slow and climb too fast.

Any data about turn performance is valuable and when you know some variables you can calculate others.


Originally posted by M_Gunz :
I would like to check, you know that 1941 SpitVB is really middle-1942?
Also that when Oleg chose data he had not only engines but specific props used?
1941/42 doesn't matter, it is SpitMkV with ~1200HP and it doesn't perform as such. If you know that both Vc's use same FM than it's obvious that modeled plane is not some obscure Russian field mod.

Never will everyone be happy, no matter how you choose. Couldn't care less http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif If I'm confident that change is justifed than I will not lose my sleep over what people says.If nothing else we might get rid of endless complaints how game doesn't reflect comparison between Spit and Faber's FW.

FC

M_Gunz
02-01-2010, 06:14 PM
You mean that Oleg doesn't tell you what data these were chosen from? No development notes?
That bodes very bad. I can see how algorithm shortcuts and tweaks won't everywhere meet
desired ends but when the goals are not based on the solid data as we were told, it is bad.
Damn. I hope that I have this wrong.

Kettenhunde
02-01-2010, 07:04 PM
A Vc without the trop filter would be nice,

IIRC, Supermarine ditched the Stokes filter in favor of a universal filter. ALL Spitfires thereafter had tropical filters at all times.

The universal filter did not degrade performance like the Stokes.

All of these filters, both Axis and Allied, where only used for take off, landing, and ground operations. In flight, the filter was opened up and all power robbing obstruction was removed.

KG26_Alpha
02-01-2010, 07:08 PM
Fabers Fw 190 was a A3

We have no A3 in v409m

What's the relevance of comparison ?


Couldn't care less Smile If I'm confident that change is justifed than I will not lose my sleep over what people says.If nothing else we might get rid of endless complaints how game doesn't reflect comparison between Spit and Faber's FW.

FC

?????

.

JG52Karaya-X
02-01-2010, 07:08 PM
The Spitfire Mk.V is indeed a very odd bird, too slow, too fast climbing and a too good turner at slow speeds.

Here's a comparison of the current stock fm against a WIP FM that I am making for a new slot mod aircraft (based on data found on wwiiaircraftperformance):

http://img.photobucket.com/albums/v639/Karaya/SpitV.jpg

The Mk.V with Merlin45 engine was cleared for 12lbs of boost in 1941, this was increased to 16lbs sometime in 1942 resulting in better performance at altitudes below the engines rated FTH.

Other than that the Merlin50/55 engined aircraft were cleared for 18lbs (but suffer from their seriously castrated superchargers)

VW-IceFire
02-01-2010, 07:37 PM
Originally posted by GBrutus:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by thefruitbat:
A Vc without the trop filter would be nice, since they served in numbers in the ETO as well as the med.

same model as the Vb can be used, just with c wing ammo loads.

There would have to be some 3D work for this, I'm afraid. You could borrow the C wing from the Mk.IX but you would end up with an extra radiator too. </div></BLOCKQUOTE>
Not much work. We already have the Vc with 2 and 4 cannon variations in-game. We just need to remove the Volkes tropical filter and fit the Aboukir one instead. That'd actually fill a huge hole in the Spitfire lineup... case in point in 1944 during D-Day there were more squadrons with Spitfire V than with the IX.

I'd like to propose:

SpitfireMkVb
SpitfireMkVbCLP
SpitfireMkVbLF
SpitfireMkVbLFCLP
SpitfireMkVc
SpitfireMkVc4xH
*SpitfireMkVcLate

I don't know the performance differences exactly but I know that we have 1941 through 1943 Vbs but that the dates and performances make no sense. Keep the Mark Vb in the performance range it should be in and add the Vc for various ETO/MTO operations where we need the higher performing V model (but not the VIII/IX). That would help quite a bit in my mind for the Spitfire world.

IMHO that is actually the "problem" with the Spitfire sometimes because you have online (or offline) scenarios where the planeset is that late 1943 lineup where the IX/VIII is a really strong contender but comparatively rare compared to a late model Vc so the IX is the dominating force. If we had a middle model then it'd solve some issues (just like how Oleg added various LaGG and Yak models once upon a time).

GBrutus
02-01-2010, 08:02 PM
IceFire, it may be a relatively small amount of 3D work required to make a late Vc model but I was under the impression that only FM changes were up for consideration here.

BillSwagger
02-01-2010, 08:12 PM
yesssssss..

Just what we need another Spitfire. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

I hope this isn't in response to a popular 190A3 mod plane that performs like an A5?

It just seems if you start tweaking one plane to match performance specs of another, that might throw off how all the other planes perform in relation to it.

HSFX offers alternatives to it in an add on entitled "Alternative FMs". I'm not taking sides, it just seems like the obvious problem with hindsight and tit for tat comparisons.
I think historical comparisons are great, and if making changes are adding new slots helps improve historical accuracy then i'm all for it.

However, too fast in climb, and too slow. I can think of at least two other planes with this problem. Lets overhaul the entire sim.

http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Bill

JtD
02-01-2010, 10:15 PM
The Mk.V with Merlin45 engine was cleared for 12lbs of boost in 1941, this was increased to 16lbs sometime in 1942 resulting in better performance at altitudes below the engines rated FTH.

Can you please name a source for the clearance of 12lb boost in 1941? To my knowledge this was only to be used for take off, and there only if the airfield was too small to permit take off at 9lb boost. I've never seen 12lb boost cleared for in flight use, only so when the limit actually was 16lb already.

csThor
02-01-2010, 10:18 PM
BillSwagger

With roundabout 300 aircraft, and a good number of them "weird" FM-wise, you gotta start somewhere. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

And this ain't about a mod Fw 190 but about the Spit Vs as they're in game now. There needs to be a solid data fundament to model the different Spit V versions as they were historically representative.

M_Gunz
02-02-2010, 01:45 AM
Originally posted by KG26_Alpha:
Fabers Fw 190 was a A3

We have no A3 in v409m

What's the relevance of comparison ?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Couldn't care less Smile If I'm confident that change is justifed than I will not lose my sleep over what people says.If nothing else we might get rid of endless complaints how game doesn't reflect comparison between Spit and Faber's FW.

FC

?????

. </div></BLOCKQUOTE>

The AFDU flew a test that very few manage to include all details when making their personal conclusions.

For one thing AFAIK, the SpitVB used was one of the first made and had been used hard in tests in Britain
and the USA. AFAIK it was a worn engine that even when new did not have the boost of what was made at the
time the comparison was run. The Faber FW was run at higher ATA than the placard in the cockpit allowed,
first roughly with British spark plugs and then with the Bosch plugs it needed, it was new when they got
it though and did develop the full 1.42 ATA which considering the engine powers the boost says that the
engine did make the power regardless.
From a copy of the text of a letter one of the pilots who flew the Spits in the test clearly stated (it
was posted at SimHQ and I provided link to it here twice) that the climb comparison was flown at the speed
the FW pilots were using in cross-channel flights, IIRC around 400kph and not Vy of either plane. MAYBE
that can be found. The point was made in the letter because the one who wrote it had wanted to pilot the
FW and was disappointed until his friend flew the FW and he realized that his friend did a better job.
You don't compare fighters for combat under conditions not used in combat.
Maybe SimHQ members can help? Community is not limited to a single forum.

M_Gunz
02-02-2010, 01:57 AM
Originally posted by JG52Karaya-X:
The Spitfire Mk.V is indeed a very odd bird, too slow, too fast climbing and a too good turner at slow speeds.

Just a thought but:

It points to excess flat-plate drag, probably from tweaking. At low speeds like in climb and turn it does not show
but when it gets faster the drag-by-speed-squared takes over. Perhaps in adjustments both parasitic drag and power
were both adjusted up-up-up? How hard to mod these both down, first power until climb is right and then drag, finally
small adjustments to try and match marks in all speed, climb and turn within the 5% or less?

KG26_Alpha
02-02-2010, 02:14 AM
Originally posted by M_Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by KG26_Alpha:
Fabers Fw 190 was a A3

We have no A3 in v409m

What's the relevance of comparison ?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Couldn't care less Smile If I'm confident that change is justifed than I will not lose my sleep over what people says.If nothing else we might get rid of endless complaints how game doesn't reflect comparison between Spit and Faber's FW.

FC

?????

. </div></BLOCKQUOTE>

The AFDU flew a test that very few manage to include all details when making their personal conclusions.

For one thing AFAIK, the SpitVB used was one of the first made and had been used hard in tests in Britain
and the USA. AFAIK it was a worn engine that even when new did not have the boost of what was made at the
time the comparison was run. The Faber FW was run at higher ATA than the placard in the cockpit allowed,
first roughly with British spark plugs and then with the Bosch plugs it needed, it was new when they got
it though and did develop the full 1.42 ATA which considering the engine powers the boost says that the
engine did make the power regardless.
From a copy of the text of a letter one of the pilots who flew the Spits in the test clearly stated (it
was posted at SimHQ and I provided link to it here twice) that the climb comparison was flown at the speed
the FW pilots were using in cross-channel flights, IIRC around 400kph and not Vy of either plane. MAYBE
that can be found. The point was made in the letter because the one who wrote it had wanted to pilot the
FW and was disappointed until his friend flew the FW and he realized that his friend did a better job.
You don't compare fighters for combat under conditions not used in combat.
Maybe SimHQ members can help? Community is not limited to a single forum. </div></BLOCKQUOTE>

My point is why compare it at all ?

Just stick to the manufacturers data.

As we have no Fw190A3 in IL2 1946 to "match" it to I wanted to know what the comparison relevance was ?

We now are having FM done on anecdotal and "what you think" basis ??

FatCat_99
02-02-2010, 02:56 AM
Originally posted by KG26_Alpha:
My point is why compare it at all ?

Just stick to the manufacturers data.

As we have no Fw190A3 in IL2 1946 to "match" it to I wanted to know what the comparison relevance was ?

We now are having FM done on anecdotal and "what you think" basis ??
You got it all wrong http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif, if modeled by manufacturer data and RL performance tests SpitfireMkV will perform exactlly the same as in "Faber's" test. Spitfireperformance site have plenty of tests with different SpitMkV, it is easy to see a trend there. And if you compare that performance data with FW190A3/4 you get exactlly the same results as in test of Faber's A3.

I only mentioned Faber's FW because that test is often used as proof how FW is porked in Il2 while all the time it was SpitfireMkV which was much bigger reason for deifference between RL and game.


Originally posted by BillSwagger :
I hope this isn't in response to a popular 190A3 mod plane that performs like an A5?

However, too fast in climb, and too slow. I can think of at least two other planes with this problem. Lets overhaul the entire sim.
Mods don't affect DT development in any way.
So we should not correct anything? SpitMkV is easy choice for a start because of it's importance for WF 1942/1943 scenario.


Originally posted by JG52Karaya-X :
The Spitfire Mk.V is indeed a very odd bird, too slow, too fast climbing and a too good turner at slow speeds.
Climb and speed are easy part, turn is little bit harder. If we take RAE BA 1640 report and use it as a base, Spit might turn even better than now. Bottom line, why would Spit turn worse than calculations predict?

FC

M_Gunz
02-02-2010, 03:43 AM
Originally posted by KG26_Alpha:
My point is why compare it at all ?

Just stick to the manufacturers data.

This has been my view about IL2 the whole time.


As we have no Fw190A3 in IL2 1946 to "match" it to I wanted to know what the comparison relevance was ?

I agree. I was only pointing out what has been shown on this forum and SimHQ about this... "issue".
When revisionists want something badly then one way to push is by playing the comparison game.
As far as I'm concerned it only leads to "notching up" of one plane after the other, climbing a ladder of abstraction.


We now are having FM done on anecdotal and "what you think" basis ??

I hope not. Look at the Gaston-thread if you think I feel different!

My post above: You mean that Oleg doesn't tell you what data these were chosen from? No development notes?
I do not understand why ask here when Oleg is supposed to have the right data before modeling? Is that only the
shapes of the planes, blueprints and photos? As above, I hope I am very wrong in this!

Kettenhunde
02-02-2010, 04:54 AM
first roughly with British spark plugs and then with the Bosch plugs it needed,

It was never flown with the correct KG adjustments for the fuel or the plugs. This was done for wartime expediency to get the trials underway before it was discovered they had the airplane. According to the report, It was bench tested after the trials. To investigate the engine adjustments, it was necessary to remove the engine.

The rough running of the engine means it is not developing full power. It is that simple.

That rough running of the engine eventually stopped the trails of WNr 313.

The report says what it says.

http://img707.imageshack.us/img707/4239/wnr313engineproblems.jpg (http://img707.imageshack.us/i/wnr313engineproblems.jpg/)

Here is the RAE investigation into this question conducted at Climb and Combat power. The conclusion is that WNr 313 performed within tolerances but at the very lower limit and did not meet the manufacturers averages for performance.

http://img17.imageshack.us/img17/4503/190specs1.jpg (http://img17.imageshack.us/i/190specs1.jpg/)

http://img17.imageshack.us/img17/6879/190specs.jpg (http://img17.imageshack.us/i/190specs.jpg/)

badatflyski
02-02-2010, 04:55 AM
Hey FC!

to start: some stats about the MK5"B"

-2285 Airframes build with Merlin45
-1042 Airframes build with Merlin46
-261 Airframes build with Merlin45M
-66 Airframes (M45+46) Modified with M45M from 42'


-76 Airframes build or modified to LFLR Vb standard >most of them (86 aiframes with M45M-
-83 Airframes build or modified to LF Vb Standard.(M45)


So, we got:

Standard MkVb > Merlin45
MkVb > Merlin45M(Cropped)
MkVb LFLR clipped wings> Merlin45M (otherwise called Clipped Clapped Cropped )-->info to be checked!!!!
MkVb LF> Merlin45 Mostly ->Clipped????

No spit Mk5b was build under the name of "LF"...
they were MU modifications.

Anyway, if you want some more info, some manuals, pilots notes, merlin curves, you got my email, so write me my darling! http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

M_Gunz
02-02-2010, 09:35 AM
Crumpp, do you have page 1 of that report? It was shown once here and I lost my copy with a drive partition.

robtek1957
02-02-2010, 09:44 AM
Why is it always pointed out that there is no FW190A3 in the game? The FW190A4 we have is a A3 with a different Radio-set!!
The only further difference is the power reduction for the eastern front which is implemented in the stock FW190A4.

Bremspropeller
02-02-2010, 10:18 AM
So, we agree we don't have an A-3 in game? http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

SUPERAEREO
02-02-2010, 11:01 AM
There was no power reduction for the FW 190 on the Eastern Front. Has anyone ever found any documents that actually say so? The only time Norbert Hanning found a reductor gate on the throttle of an FW 190 was with an operational training unit in Germany and he promptly proceeded to remove it.

Why anyone would believe that anyone would go to war in a castrated machine is beyond me.

Honestly.

blairgowrie
02-02-2010, 11:24 AM
You can get il2 Stab from Mission 4today:

http://mission4today.com/index...file=details&id=2169 (http://mission4today.com/index.php?name=Downloads&file=details&id=2169)

Excellent program for setting icon distances amongst other things.

SUPERAEREO
02-02-2010, 11:26 AM
Wrong post Blairgowrie! http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

GBrutus
02-02-2010, 11:34 AM
Originally posted by SUPERAEREO:
Why anyone would believe that anyone would go to war in a castrated machine is beyond me.

Have to say I've wondered about this myself.

blairgowrie
02-02-2010, 11:48 AM
Originally posted by SUPERAEREO:
Wrong post Blairgowrie! http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Thank you sir. I look at too many threads every day so it is easy to get confused. I have now posted in the correct thread.

M_Gunz
02-02-2010, 11:56 AM
Originally posted by SUPERAEREO:
There was no power reduction for the FW 190 on the Eastern Front. Has anyone ever found any documents that actually say so? The only time Norbert Hanning found a reductor gate on the throttle of an FW 190 was with an operational training unit in Germany and he promptly proceeded to remove it.

Why anyone would believe that anyone would go to war in a castrated machine is beyond me.

Honestly.

Butch2K showed documents on the period of derating of FW engines, also the reasons and causes being burned exhaust
stacks, possibly more. This was debated at length more than once and amazingly also accepted by the grognards with
the shelves of books, most of who have quit the Zoo years ago. You can ask Kurfurst, I am sure that he collected
all the documents pertaining to this. Butch was/is a very fair and thorough person when it came to research.

Why anyone would go to war in a machine that would burn up or seize up is beyond me, but things happened to perhaps
every plane that caused problems and needed fixing. The harder you push the possible, the harder it pushes back.

SUPERAEREO
02-02-2010, 12:15 PM
That the first series of the Würger suffered from engine problems is a well known fact.

That the BMW engine was derated for the Eastern Front is pure baloney.

After all it was much easier to survive a crash landing in Russian terra firma than hypotermia after ditching in the Channel.

Bremspropeller
02-02-2010, 12:24 PM
That the BMW engine was derated for the Eastern Front is pure baloney.

So if you say that, it gotta be the truth http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

They just put a screw into the throttle-gate to stop the throttle and thus effectively limiting power-output.
One could remove the screw and go full power in about a minute...

Also, crash-landing on russian "terra firma" was considered less inviting by the Germans than taking a swim in the Channel.

Conserving engine-life in that kind of environment doesn't seem to be that ridiculous at all.

Especially with only little experience on maintaining the type for the first few weeks and months and considering the somewhat less-performing russian fighters.

KG26_Alpha
02-02-2010, 12:32 PM
Originally posted by robtek1957:
Why is it always pointed out that there is no FW190A3 in the game? The FW190A4 we have is a A3 with a different Radio-set!!
The only further difference is the power reduction for the eastern front which is implemented in the stock FW190A4.


Originally posted by Bremspropeller:
So, we agree we don't have an A-3 in game? http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

and again http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Errrrm......... so we have no A3 then.

Holtzauge
02-02-2010, 12:35 PM
FC: Since you asked for Spitfire turnrate estimates, I did a simulation of the Mk 5, 9 and 14 for you:

http://img.photobucket.com/albums/v210/Holtzauge/Spitfirestationaryturnratepropandje.jpg

I have only modelled the Mk5 with the Merlin 45 so far. If you have good Merlin power/altitude charts I could do the rest. I especially lack exhaust thrust data.

If you are getting weird results maybe it has to do with the Merlin variant installed? I suspect that turn times at 1 km altitude will vary a lot depending on if the Mk5 is equipped with a Merlin 45, 45M or 50M seeing how much they vary in critical altitude and power due to the cropped superchargers....

Another question is for what weights do you want results? The results vary quite a lot with weight. I included two different weights For the Mk5 to illustrate the point. Another thing: What Clmax do you intend to use for the Spitfire? The above assumes Clmax=1.36 based on data from the RAE.

BTW: Curious to hear from you again how the compressibility modelling is going? I have some speed/altitude data data for the Spitfire Mk5 with Merlin 50M if you are interested.

Holz

M_Gunz
02-02-2010, 02:38 PM
Originally posted by SUPERAEREO:
That the first series of the Würger suffered from engine problems is a well known fact.

That the BMW engine was derated for the Eastern Front is pure baloney.

After all it was much easier to survive a crash landing in Russian terra firma than hypotermia after ditching in the Channel.

You are trying to change the answer. It is NOT about WHERE. It is about WHEN.
ALL were derated between those certain dates. And there was more than one problem with heat during FW development.

Get the freaking documents and find out for yourself if your unders are in a twist.

And BTW, Oleg had posted the same info.
Closest FW to A-3 at full boost is the A-5 and it is plenty close enough.

You know that the Faber A-3 was placarded not to run beyond, IIRC 1.35ATA?

Butch2K's new All About Warfare site. (http://www.allaboutwarfare.com/) -- Join and spend YOUR TIME getting the info, I've seen this show already.

BillSwagger
02-02-2010, 02:58 PM
I have to think the output is there, but i can't ignore the fact sheets that detail such use was limited to 30 seconds intervals for a maximum of 3 minutes total. That brings quite a different conclusion to the table considering engine performance.
The only marked difference in performance between eastern and western front planes was maximizing low altitude speed, which Russian fighters were very proficient at. You might recognize trying to get higher boost pressures closer to sea level leads to more over boosting problems, even in a Spitfire. In fact, reaching full boost was something you could rarely if ever do at sea level with out blowing the engine with in short time (overboosting).

What happens is people pick the biggest and best berry off the data tree, and ignore all the not so ripe ones.

Kettenhunde
02-02-2010, 04:58 PM
What Clmax do you intend to use for the Spitfire?


There is no need to guess or draw erroneous conclusions from misinterpreted reports.

The stall velocity of the Spitfire series is very well documented under know conditions. It is very easy to take that information and using the forces required simply change the parameters to meet any other Spitfire variant under conditions desired.

http://jsbsim.sourceforge.net/spit_stalling.pdf

The Spitfire POH's also list the stalling speed and conditions.

SUPERAEREO
02-02-2010, 05:01 PM
Originally posted by M_Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by SUPERAEREO:
That the first series of the Würger suffered from engine problems is a well known fact.

That the BMW engine was derated for the Eastern Front is pure baloney.

After all it was much easier to survive a crash landing in Russian terra firma than hypotermia after ditching in the Channel.

You are trying to change the answer. It is NOT about WHERE. It is about WHEN.
ALL were derated between those certain dates. And there was more than one problem with heat during FW development.

Get the freaking documents and find out for yourself if your unders are in a twist.

And BTW, Oleg had posted the same info.
Closest FW to A-3 at full boost is the A-5 and it is plenty close enough.

You know that the Faber A-3 was placarded not to run beyond, IIRC 1.35ATA?

Butch2K's new All About Warfare site. (http://www.allaboutwarfare.com/) -- Join and spend YOUR TIME getting the info, I've seen this show already. </div></BLOCKQUOTE>


My unders are not in any twist.

By the time the FW 190 was employed in force on the Eastern Front NO restrictions were enforced.

Then again, ayone is free to believe in fairytales.

FatCat_99
02-02-2010, 05:18 PM
Originally posted by Holtzauge:
FC: Since you asked for Spitfire turnrate estimates, I did a simulation of the Mk 5, 9 and 14 for you: Thanks for the chart, can you make climb rates, for SpitMkV only, just to see if they are good match for RL tests.



I have only modelled the Mk5 with the Merlin 45 so far. If you have good Merlin power/altitude charts I could do the rest. I especially lack exhaust thrust data. I don't have it but I'm mostly interested in trends here.


If you are getting weird results maybe it has to do with the Merlin variant installed?
I'm getting similar results as you although my turn rate is higher but I have too good climb so I perhaps have too much thrust at lower speeds.

Problem in game is with old Spits, you can see that on second page of this thread, Karaya posted Il2compare data. It's easy to see that this plane is too slow and its climb is too good. This Spit is using Merlin 45, weight is 2960kg.



I suspect that turn times at 1 km altitude will vary a lot depending on if the Mk5 is equipped with a Merlin 45, 45M or 50M seeing how much they vary in critical altitude and power due to the cropped superchargers....
We have couple of MkV variants and some are using different engines but for now we can focus on Merlin 45.



What Clmax do you intend to use for the Spitfire? The above assumes Clmax=1.36 based on data from the RAE. Tough question, I'll have to use one which will do least damage to flight model, same is with any other parameter. http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif



BTW: Curious to hear from you again how the compressibility modelling is going?
It will not be ready for 4.10



Originally posted by badatflyski :
Standard MkVb > Merlin45
MkVb > Merlin45M(Cropped)
MkVb LFLR clipped wings> Merlin45M (otherwise called Clipped Clapped Cropped )-->info to be checked!!!!
MkVb LF> Merlin45 Mostly ->Clipped????

And how to distribute these to what we have in game?
Currentlly:
SPITFIRE5C4 Merlin45
SPITFIRE5C2 Merlin45
SPITFIRE5BLFCLP Merlin50
SPITFIRE5BLF Merlin50
SPITFIRE5BCLP Merlin45
SPITFIRE5B Merlin45

Another question is which boost level to use .

FC

VW-IceFire
02-02-2010, 05:44 PM
Originally posted by GBrutus:
IceFire, it may be a relatively small amount of 3D work required to make a late Vc model but I was under the impression that only FM changes were up for consideration here.
I get overexcited about anything new to fly and I always felt there was a bit of a hole in the lineup... and that the Mark V was an "also ran" considering everyone flies the IX +25 http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif Daidalos does put together some excellent new models so I figured we aren't asking for a whole new model here. We already have all of the bits and pieces nicely modeled in the Seafire III and Spitfire Vc tropical. Just not in one place...

In any case I can always nudge or ask and if the answer is no... then that is ok too.

GBrutus
02-02-2010, 06:08 PM
Nudge away, IceFire. You're absolutely right, there's no harm in asking and I'd like to see a more representative lineup myself. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Kwiatos
02-02-2010, 06:19 PM
Ok some my shots http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

SPitfire MK Va +12 lbs vs VB +12 lbs ( 1941)

Nominal power - +9lbs
WEP - +12lbs

http://i50.tinypic.com/vs2tdx.jpg

Spitfire MK VB +12 vs VB CW Merlin 45 +16lbs ( 1942)

http://i46.tinypic.com/2wowz6h.jpg

Spitfire MK VB LF Merlin 50M +18lbs vs VB LF CW

Nominal Power - +12lbs
WEP - +18 lbs

http://i47.tinypic.com/mj20bl.jpg


Spit VC Trop +16 lbs vs VC LF Trop +18lbs

http://i46.tinypic.com/33k816s.jpg


Now little more interesting

Spit VB +12 lbs vs IX F Merlin 61 +15 lbs

http://i47.tinypic.com/wl62oz.jpg

And now even more interesting http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Spit MKVB +12 lbs vs Fw 190 A-3 1.42Ata 2700 RPM

http://i48.tinypic.com/2rz9ohl.jpg

and IX F Merin 61 vs A-3

http://i49.tinypic.com/2uysrut.jpg


All are based at Smolensk Map, with 100% fuel.

JG53Frankyboy
02-03-2010, 04:47 AM
i realy like the idea to overwork the MkV series in the game http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif
it was a so important plane !

and so im sorry for that:
if possible perhaps Daidalos could also look in the 109series from G-2 to G6 ,G6Late and G6AS....
to make a G-2 with reduced power for 42, to look about the FM differences between the G-2 and G-6 and perhaps to make a real G-6AS without MW50 but with better alt performance than the G-6Late.

and a boosted P-51D (just change the D-20 to the 150octan level and keep the D-5 as it is) , oh well http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif
and a difference in performance bwtween the two F6Fs would also be nice.
all of that would require no 3D work............

sorry again http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif
and now please go forward with the Spitfire V http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Holtzauge
02-03-2010, 12:17 PM
Originally posted by BillSwagger:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FatCat_99:
Hi,
we have some very strange performing Spits MkV in game

strange how?

The rule on spits is that generally, the bigger the engine, the better the rate, but the wider the radius.

Cannons usually imply more weight, so that should also decrease turn performance. I just wondered if empty weight of cannon wielding Spits was more or less than that of a Spit with 303s.

I saw on another forum where a person had posted Russian tests figures. There were some interesting figures, most of which put the SpitV at the top of turn rate, measured in time it takes to make 1 complete circle (17-18 seconds). Whats difficult about these studies is that there is no indication of radius, but i have to guess that's a best sustained figure.


Bill </div></BLOCKQUOTE>

Yes, my guess is that it is the best sustained to. These are the numbers I get in my simulation for best turnrate at W=2960 Kg Merlin 45 +9 boost:

Vt(Km/h) R (m) n (deg/s) turn time (s)
241.86 186.11 2.67 20.68 17.41

So the radius would be around 185 m....

JtD
02-03-2010, 12:33 PM
May I repeat my question as to when, where and how 12lb boost were cleared for the Merlin45 as in the Spit V?

Holtzauge
02-03-2010, 01:11 PM
Originally posted by FatCat_99:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Holtzauge:
FC: Since you asked for Spitfire turnrate estimates, I did a simulation of the Mk 5, 9 and 14 for you: Thanks for the chart, can you make climb rates, for SpitMkV only, just to see if they are good match for RL tests.



I have only modelled the Mk5 with the Merlin 45 so far. If you have good Merlin power/altitude charts I could do the rest. I especially lack exhaust thrust data. I don't have it but I'm mostly interested in trends here.


If you are getting weird results maybe it has to do with the Merlin variant installed?
I'm getting similar results as you although my turn rate is higher but I have too good climb so I perhaps have too much thrust at lower speeds.

Problem in game is with old Spits, you can see that on second page of this thread, Karaya posted Il2compare data. It's easy to see that this plane is too slow and its climb is too good. This Spit is using Merlin 45, weight is 2960kg.



I suspect that turn times at 1 km altitude will vary a lot depending on if the Mk5 is equipped with a Merlin 45, 45M or 50M seeing how much they vary in critical altitude and power due to the cropped superchargers....
We have couple of MkV variants and some are using different engines but for now we can focus on Merlin 45.



What Clmax do you intend to use for the Spitfire? The above assumes Clmax=1.36 based on data from the RAE. Tough question, I'll have to use one which will do least damage to flight model, same is with any other parameter. http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif



BTW: Curious to hear from you again how the compressibility modelling is going?
It will not be ready for 4.10



Originally posted by badatflyski :
Standard MkVb > Merlin45
MkVb > Merlin45M(Cropped)
MkVb LFLR clipped wings> Merlin45M (otherwise called Clipped Clapped Cropped )-->info to be checked!!!!
MkVb LF> Merlin45 Mostly ->Clipped????

And how to distribute these to what we have in game?
Currentlly:
SPITFIRE5C4 Merlin45
SPITFIRE5C2 Merlin45
SPITFIRE5BLFCLP Merlin50
SPITFIRE5BLF Merlin50
SPITFIRE5BCLP Merlin45
SPITFIRE5B Merlin45

Another question is which boost level to use .

FC </div></BLOCKQUOTE>

OK, here are both the turn rate and climb for W=2960 Kg.

http://img.photobucket.com/albums/v210/Holtzauge/SpitfireMk5stationaryturnratepropan.jpg

http://img.photobucket.com/albums/v210/Holtzauge/SpitfireMk5climbchartpropandjetPA29.jpg

I also think the top speed seems to low. I get 602 Km/h (374 mph) at critical altitude which compares rather well with the 372 mph figure I've seen at Spitfireperformance.com.

R_Target
02-03-2010, 02:27 PM
Originally posted by JG53Frankyboy:
and a difference in performance bwtween the two F6Fs would also be nice.
all of that would require no 3D work............

Absolutely. Both perform as mid-1943 F6F-3.

thefruitbat
02-03-2010, 02:31 PM
Originally posted by R_Target:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JG53Frankyboy:
and a difference in performance bwtween the two F6Fs would also be nice.
all of that would require no 3D work............

Absolutely. Both perform as mid-1943 F6F-3. </div></BLOCKQUOTE>

+1, i love the hellcat, and would love to see a proper late war version http://forums.ubi.com/images/smilies/25.gif

M_Gunz
02-03-2010, 02:56 PM
Come to think of it, since FB the optimistic climb at low speed is true of just about for every plane.
One of the first FB patches addressed the worst I remembered, the Hurricane was almost like a helicopter.

Viper2005_
02-03-2010, 08:01 PM
Originally posted by Holtzauge:
I have only modelled the Mk5 with the Merlin 45 so far. If you have good Merlin power/altitude charts I could do the rest. I especially lack exhaust thrust data. You need to get hold of "The performance of a supercharged aero engine"

http://www.rolls-royce.com/abo...rged_aero_engine.jsp (http://www.rolls-royce.com/about/heritage/publications/technical-series/supercharged_aero_engine.jsp)

This has essentially everything you need to model the Merlin (and it does pretty well for the Griffon as well). I've only ever used it to simulate at the design point (FTH) because in the past I didn't feel ready to take on the task of matching supercharger maps to handle the off-design case. I reckon I could do it properly now, but it'd be quite a serious task for which I probably won't have the time or energy until perhaps November.

The nice thing about the model is that because it calculates supercharger performance as a function of diameter, you can get directly at the effects of cropping the supercharger. Also, because it's a general model of the Merlin, you can use it to predict the performance of marks for which you don't have good data.

The model isn't quite perfect for later engines (IIRC it's 1941 vintage) but you can generally get within a couple of % of the correct figures for 1945 engines, which is pretty impressive all things considered. There is also a certain satisfaction in knowing that you're using the "real" model used during WWII.

My time is somewhat limited at the moment, but I'm happy to collaborate. I generally build my performance models in Excel 2007. I'd have to start this from scratch because the last time I did this was getting on for 10 years ago and I've had a few PCs since then...

Originally posted by Holtzauge:
If you are getting weird results maybe it has to do with the Merlin variant installed? I suspect that turn times at 1 km altitude will vary a lot depending on if the Mk5 is equipped with a Merlin 45, 45M or 50M seeing how much they vary in critical altitude and power due to the cropped superchargers....

Another question is for what weights do you want results? The results vary quite a lot with weight. I included two different weights For the Mk5 to illustrate the point. Another thing: What Clmax do you intend to use for the Spitfire? The above assumes Clmax=1.36 based on data from the RAE.

BTW: Curious to hear from you again how the compressibility modelling is going? I have some speed/altitude data data for the Spitfire Mk5 with Merlin 50M if you are interested.

Holz

I'm also very interested in compressibility modelling, as this is the biggest deficiency in IL2 at present, and has a huge impact upon the character of high altitude combat. I have some limited but interesting data on this (with emphasis upon the handling deficiencies encountered at high Mach number by various types) if you're interested...

M_Gunz
02-04-2010, 03:20 AM
Originally posted by Viper2005_:
I'm also very interested in compressibility modelling, as this is the biggest deficiency in IL2 at present, and has a huge impact upon the character of high altitude combat. I have some limited but interesting data on this (with emphasis upon the handling deficiencies encountered at high Mach number by various types) if you're interested...

What different kinds of effects are there? These are ones I'd like see *any* of.

There is the big bad drag increase. You going to do insane-speed prop drag with effects of different engine settings
in real time? Or compute the curve and come up with a reasonable, fast running, match like ( speed / compression
start cubed ) and factor that as added drag? Cube ain't steep enough? Change the compression start.

I have a P-39 stick pitch force per G with speed chart that was posted here.
There are curves to show real vs differently calculated data and I'd take *any* of those as an improvement on now.
I think that a hyperbola that fit between the real and calculated curves on that chart would be better than now,
the real shape isn't so far off that anyway.
Set in cement would have meaning.

Shock wave blocking control surfaces could just be flagging those surfaces off in the next FM iteration.
Are the shock waves on the surfaces? Any control shake could be as easy as running a stick-shake daemon.
FFB would be as big an edge as TIR, maybe bigger.

The faster you go the less AOA you need and in a dive you need lift even less, gotta keep dropping the nose to
maintain your dive angle and the nose tucks maybe before you get any trouble. And then... center of lift moves
back? Does IL2 allow CL to move? CoG can't as IL2 stands... be nice to have that, solve a problem or two.

Got more? Somehow I bet you do.

Holtzauge
02-04-2010, 05:53 AM
Originally posted by Viper2005_:

I'm also very interested in compressibility modelling, as this is the biggest deficiency in IL2 at present, and has a huge impact upon the character of high altitude combat. I have some limited but interesting data on this (with emphasis upon the handling deficiencies encountered at high Mach number by various types) if you're interested...

Below is a chart for the P-51D that I posted together with Wurkeri about a year ago. I found the post but unfortunately the pics are gone so I repost them.

As you say, the missing compressibility modelling would be nice to add and I look forward to hearing how FC plans to do this. I did discuss it briefly with him off-line some time ago and I appreciate that it may be a problem to do this in real-time within the limitations set by the current FM.

Since I do not have to do this in real-time I have developed a brute force method of itertion which eventually produces the results I want by crunching the numbers until they converge.

As an example of what I use as input, here is the type of drag model I use. This can be, and is, set individually for each a/c I modelled.


http://img.photobucket.com/albums/v210/Holtzauge/IL2Cdocomparison.jpg

Here is a chart showing the results of my C++ simulation together with devicelink data from IL2 that Wurkeri produced. As you can see they are pretty consistant up until the onset of compressibility.

http://img.photobucket.com/albums/v210/Holtzauge/P51DCandIl2BnZcomp.jpg

To spare someone from posting that I should not complain about the lack of compressibilty and that we should be grateful for what we have: This is by no means meant as a critique of IL2. The Il2 series is a fantastic achivement and I greatly respect the developers for what they have done. http://forums.ubi.com/images/smilies/11.gif

However, that does not mean I would not prefer to see compressibility modelled in BOB as compared to yet fancier graphics...

If CPU is a problem to do the gradual drag rise I use in the C++ code in IL2, then one could do something really simple like having a mach "wall" which could could be set individually for each a/c. E.g a bit higher for a/c like the P51, and a bit lower for a/c which exhibit an earlier subsonic drag rise like the Me109.

BTW: Thanks for the tip about the RR document on supercharging Viper, I may try to get hold of it later. Finally, I'm definitely interested in handling characteristics at high mach. I have some data myself in this area so maybe you could drop me a PM and we could discuss this some more off-line?

FatCat_99
02-04-2010, 06:28 AM
Originally posted by JtD:
May I repeat my question as to when, where and how 12lb boost were cleared for the Merlin45 as in the Spit V?
This is a good question and that has to be answered first. So what would be most representative variants of SpitMkV ?


Originally posted by JG53Frankyboy :
and so im sorry for that:
if possible perhaps Daidalos could also look in the 109series from G-2 to G6 ,G6Late and G6AS....
to make a G-2 with reduced power for 42, to look about the FM differences between the G-2 and G-6 and perhaps to make a real G-6AS without MW50 but with better alt performance than the G-6Late.

and a boosted P-51D (just change the D-20 to the 150octan level and keep the D-5 as it is) , oh well
and a difference in performance bwtween the two F6Fs would also be nice.
Spit is not the only plane that will be tweaked, with some planes problem is that we have very limited options (Hellcat for example)because of Grumman issue we can't add any new variant so we must get most out of what we have in game.


Originally posted by Holtzauge :
OK, here are both the turn rate and climb for W=2960 Kg
Thanks again, so all of the calculations match pretty well together.


Originally posted by Viper2005_ :
I'm also very interested in compressibility modelling, as this is the biggest deficiency in IL2 at present, and has a huge impact upon the character of high altitude combat. I have some limited but interesting data on this (with emphasis upon the handling deficiencies encountered at high Mach number by various types) if you're interested...
Compressibility is LesniHU's project but he is very busy at work lately so he can't do much for Il2. We all agree in DT that compressibility is one of the most important features still missing in Il2 and we will do our best to include it in 4.11.

I'll tell LesniHU to contact you. If you know good model for predicting tactical and critical Mach numbers that would be most helpful.

Our FM tester is experienced RL pilot with experience in jet fighters but he flown some warbirds too and have first hand experience with compressibility. We made new model for P-38 but for 4.11 we need global model, treating each plane individually is out of the question in sim with 200+ planes.

Now ,please, lets go back to SpitfireMkV performance.

FC

Xiolablu3
02-04-2010, 07:13 AM
You mean Grumman will even jump on a non-profit mod?

FatCat_99
02-04-2010, 07:29 AM
Originally posted by Xiolablu3:
You mean Grumman will even jump on a non-profit mod?
We are not making mod, we are making offical patch for Il2 just like we did with 4.09. Patch will be released with UBI,1C and Maddox Games logos, this is not a joke, this is serious business which can cost you lot of money if you make a mistake.

It doesn't matter if patch is free and that we are not payed for what we do, Oleg made many free patches before but that doesn't change a fact that Grumman can ask big money for their equipment. And they don't own planes only, they own something like 1/3 of American war machinery. That seriously limits our options when it comes to American war effort.

FC

Kwiatos
02-04-2010, 10:32 AM
I think +12 lbs WEP in Merlin 45 was allowed from begining ( 1941)

+9 lbs was nominal power ( combat and continous) - all know RAF test was made initialy at these power ( see climb and speed test for Spits MK V at Spitfire Performance Testing site)

Also see power ratings for early Merlins.

Merlin 3 from 1940 since used 100 octan fuel was cleared for + 9lbs combat power and + 12lbs WEP power ( instead 6 1/2 Lbs at 87 octan).

Merlin XII also from begining ( 1940) had +9lbs combar power and +12 lbs WEP.

The same was with Merlin 45. So 1941 for Merlin 45 would be +9lbs combat power and +12lbs WEP, then from 1942 was +9lbs combat and +16 lbs WEP ( +12lbs was take off power).

Kettenhunde
02-04-2010, 10:40 AM
Here is a chart showing the results of my C++ simulation together with devicelink data from IL2 that Wurkeri produced.

Just a suggestion, label your chart something besides zero lift drag.

In subsonic incompressible flow theory, zero lift drag does not change over velocity.

Not trying to beat you up, It just looks silly when you show that chart trying to discuss drag rise due to compressibility.

There is no clear agreement as to exactly where drag rise begins. The solution is found more within the context of a particular discussion. What is significant in one case may not be significant in another.

In subsonic propeller designs, it is not considered significant at all. In subsonic incompressible flow theory, A given amount of horsepower delivers a given performance when we tally the forces required.

Oleg and Maddox Games has not skipped or missed anything.

However, the percentage increase in drag coefficient due to compressibility can be estimated by the empirically derived relationship. Technically this is due to the parasitic portion of drag but is expressed as a function of the total drag:

Mach Number^2 / Number of engines + Mach Number^2 / Number of engines factor of 10

For a SE fighter traveling at Mach .79:

.79^2 / 1 + (.79^2 / 10 ) = 68.7% rise in drag coefficient due to the effects of compressibility.

If our forces required Drag Coefficient was 1, then .687 of it is due to compressibility effects.

My suggestion is if you want to model the onset of the effects of compressibility, simply code the effects subroutine to occur when your drag rise reaches a specific percentage rise if that is possible. Even easier is just have it occur at a specific mach number.

Maybe that will help you out.

JtD
02-04-2010, 12:16 PM
Originally posted by Kwiatos:

+9 lbs was nominal power ( combat and continous) - all know RAF test was made initialy at these power ( see climb and speed test for Spits MK V at Spitfire Performance Testing site)

This does not match with the statements that can be found for several tests. These are 9lb / 2850rpm maximum for climbing, 9lb / 3000 rpm all out level.
I've seen several 12 lb statements, but all of these were for take off only.

The other Merlins are somewhat different engines, so I don't think they are relevant.

Holtzauge
02-04-2010, 01:03 PM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Here is a chart showing the results of my C++ simulation together with devicelink data from IL2 that Wurkeri produced.

Just a suggestion, label your chart something besides zero lift drag.

In subsonic incompressible flow theory, zero lift drag does not change over velocity.

Not trying to beat you up, It just looks silly when you show that chart trying to discuss drag rise due to compressibility.

There is no clear agreement as to exactly where drag rise begins. The solution is found more within the context of a particular discussion. What is significant in one case may not be significant in another.

In subsonic propeller designs, it is not considered significant at all. In subsonic incompressible flow theory, A given amount of horsepower delivers a given performance when we tally the forces required.

Oleg and Maddox Games has not skipped or missed anything.

However, the percentage increase in drag coefficient due to compressibility can be estimated by the empirically derived relationship. Technically this is due to the parasitic portion of drag but is expressed as a function of the total drag:

Mach Number^2 / Number of engines + Mach Number^2 / Number of engines factor of 10

For a SE fighter traveling at Mach .79:

.79^2 / 1 + (.79^2 / 10 ) = 68.7% rise in drag coefficient due to the effects of compressibility.

If our forces required Drag Coefficient was 1, then .687 of it is due to compressibility effects.

My suggestion is if you want to model the onset of the effects of compressibility, simply code the effects subroutine to occur when your drag rise reaches a specific percentage rise if that is possible. Even easier is just have it occur at a specific mach number.

Maybe that will help you out. </div></BLOCKQUOTE>

Kettenhunde: Do me a favour and stay away from the discussion.

I used to think you were a charlatan trying to dupe people but I have come to understand that you really do not understand basic physics and aerodynamics and that unfortunately, despite frequent proof to the contrary, you seem to be unable to grasp this concept yourself.

In your infinite wisdom you start lecturing on how to do compressibility modelling which, as usual, is gibberish.


Now let me repay the compliment: Before even attempting to look into compressibility, it is advisable to have a fair understanding of the part of the flight envelope in which incompressible theory can be used with good approximation, namely sustained turn performance.

Your post here on P-47 sustained turn performance is painful to behold and a good place to start:

http://forums.ubi.com/eve/foru...83/m/2221055328/p/10 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2221055328/p/10)

Now I suggest you go back there and get this right before even attempting to look into the compressibility part of the envelope.

There is no way the P-47 in the linked example can have a sustained turn rate like 22 degrees/s.

A realistic value at 20,000 ft is around 9 degrees/s.

The P-47 cannot even sustain 22 degrees/s at 1 Km altitude. At 1 Km it can do around 14-15 degrees/s.

FYI: The way I present Cdo and drag rise is how you will find it presented in WW2 German, NACA and RAE reports so I think I'm in good company.

So get the incompressible stuff right first before lecturing on thing you do not understand. Then maybe you can get some street cred on the compressibility parts.

And don't bother to reply. I'm done with the long threads that result when you're exposed. That is why I stay away from the nonsense you post here like the linked thread above and only read them for the entertainment value.

You are ignored.

Kettenhunde
02-04-2010, 04:24 PM
Holtzauge,

How about doing me a favor and quit being so defensive, take a deep breath, and look at what your doing...



There is no way the P-47 in the linked example can have a sustained turn rate like 22 degrees/s.

MMMM....

http://forums.ubi.com/eve/foru...781013728#2781013728 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2221055328?r=2781013728#2781013728)


I need to explain the difference between Equivalent Airspeed and True Airspeed to you again.


180KEAS * 1.37 SMOE = 247KTAS

ROT = (1091 * tan 73 )/ 247 = 14 degrees a second @ .85 np

More like 14 degrees a second.....

Depending on the mathematical assumptions that specific performance can change even more.

Performance trends in the realm of significant digits is all you can predict NOT specific performance.

What I am telling you is your game uses subsonic incompressible flow theory to derive its FM's. That is obvious as the CDo remains constant and a compressibility correction is applied to gain our aircraft True Airspeed.

When you do compressible flow theory everything is in TAS and worked backwards in relation to the free-stream velocity. We take that velocity and begin building an vehicle in it mathematically. No tabular compressibility correction is applied. Instead the boundary of the shock is mapped and generally we deal in coefficients of pressure using one of several popular theories.

That is how we design airplanes to do what we want at the speeds we want them too!

Mixing compressible flow theory elements with incompressible flow will not yield good results.

Stick to one or the other as the effects of compressibility are already accounted for in your velocity corrections for subsonic incompressible flow.

There are much better ways to make a very realistic simulation of transonic flight.

You can post whatever silliness you like but that is the facts.

Holtzauge
02-05-2010, 04:33 AM
Now to return to the reason for this thread: Spitfire Mk5 performance.

Unfortunately I have no data on the Merlin 45 at +12 boost. Mike and Neil have been kind enough to post data for +16 boost at Spitfireperformance.com so I have added turn and climb performance for this boost level as well.

The Spitfire Mk5 at +16 boost certainly looks like a performer http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

http://img.photobucket.com/albums/v210/Holtzauge/SpitfireMk5statturnratePA29100205.jpg

http://img.photobucket.com/albums/v210/Holtzauge/SpitfireMk5climbchartPA29100205.jpg

Holtzauge
02-05-2010, 08:03 AM
Since this thread is about Spitfire Mk5 and not about the turn capabilities of the P-47, those who wish to see more on this subject can do so here:
http://forums.ubi.com/eve/foru...301043038#6301043038 (http://forums.ubi.com/eve/forums?a=tpc&s=400102&f=23110283&m=2221055328&r=6301043038#6301043038)

M_Gunz
02-05-2010, 10:29 AM
Why bring it up anyway?

Kurfurst__
02-05-2010, 10:29 AM
Originally posted by Holtzauge:
The Spitfire Mk5 at +16 boost certainly looks like a performer http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

At least on your charts. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif But your charts also show something like 16 seconds for a 360 degree turn for the Mk IX LF at +18, and the Russians measured 18 secs in flight trials.. same as the Mk V btw. So I guess you missed something in your calculations.

I am not sure if the OP was interested in finding good "nominal" specifications for the Mark V, or rather trying to find such for real life, but in either case, the following excerpt from an 1943 British report should be of interest.

http://i38.photobucket.com/albums/e133/Kurfurst/Spitfire/Spitfire5_speeds.png

Edit: fixed link

thefruitbat
02-05-2010, 11:00 AM
can't see report http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif

Kurfurst__
02-05-2010, 11:11 AM
Fixed and uploaded it to elsewhere. Hopefully it now shows up..

Kettenhunde
02-05-2010, 12:18 PM
Why bring it up anyway?


It redirects attention???

The internet BBS version of Look at the Monkey....

http://www.youtube.com/watch?v=1qv0cy0843U

http://forums.ubi.com/images/smilies/partyhat.gif

GBrutus
02-05-2010, 12:19 PM
Which particular report is this, Kurfurst? I'd like to see more of it if possible. I note it mentions that the speed was well down 'at one stage' suggesting improvements were already being made i.e, internal armoured glass and other external refinements...

Kettenhunde
02-05-2010, 12:32 PM
Which particular report is this, Kurfurst? I'd like to see more of it if possible. I note it mentions that the speed was well down 'at one stage' suggesting improvements were already being made i.e, internal armoured glass and other external refinements...

They almost always corrected shortly after they are discovered.

Real firms don't sit around ignoring problems and real customers don't settle for items that don't work as advertised.

Of course some people think that bit of common sense only applies to a particular side.

I don't see Kurfurst as claiming the issues were not resolved.


So I guess you missed something in your calculations.

His stuff is very optimistic but that optimism extends to a few designs.

When I add in environmental effects on propeller efficiency and convert to TAS, I still can't get some of his numbers on certain aircraft.

JtD
02-05-2010, 12:45 PM
I'd say poor production standards or shortcomings in finish hardly matter for the game, as it is supposed to reflect the performance of planes in a very good condition.

Kettenhunde
02-05-2010, 01:31 PM
If you use manufacturers averages, understand stability and control, q-limits, mach effects, and incompressible flow theory, you can do a very good and realistic FM for subsonic propeller designs. In fact that is the theory of choice.

You don't need or want outliers, either optimistic and pessimistic.

JtD
02-05-2010, 02:08 PM
How many tropicalized Spitfires MkVc were equipped with the Merlin 46?

Also, does anybody have loading plans for the various V models?

FatCat_99
02-05-2010, 04:22 PM
Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Holtzauge:
The Spitfire Mk5 at +16 boost certainly looks like a performer http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

At least on your charts. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif But your charts also show something like 16 seconds for a 360 degree turn for the Mk IX LF at +18, and the Russians measured 18 secs in flight trials.. same as the Mk V btw. So I guess you missed something in your calculations.

I am not sure if the OP was interested in finding good "nominal" specifications for the Mark V, or rather trying to find such for real life, but in either case, the following excerpt from an 1943 British report should be of interest.
</div></BLOCKQUOTE>
Holtzauge numbers might be somewhat optimistic for 16lb at least climb seems to be too good in comparison with the one test at 16lb on spitfireperformanc . On the other hand we don't know much about Russian test, how many test they made with the plane, what was the condition of plane and engine, were they flew plane at optimum speed etc.

NACA F2A3 test is good example how hard is to meassure turn performance, you can find almost 10 seconds ( this is extreme, of course)difference between turn times at same speed.

My goal is to find what would be most representative SpitMkV variants and their performance. So far we can only conclude that 9lb variant is something that should be modeled. For 12lb nobody showed so far any RL document. I only found in 16lb test reference to 12lb as take off setting and special emergency setting prior to itroduction of 16lb.

FC

Kettenhunde
02-05-2010, 07:39 PM
I don't think +12 was approved for very long at all.

The Merlin 45 boost seems to have gone from +9 to +16 very quickly. Even the RAE trials of WNr 313 mention that since the trials were conducted, the Spitfire Mk Vb has been approved for +16lbs.

http://img268.imageshack.us/img268/2876/pro190surveyc1.jpg (http://img268.imageshack.us/i/pro190surveyc1.jpg/)

hop2002
02-06-2010, 03:32 AM
I believe 12 lbs boost was used in the Spitfire V from the start. I think the RAF simply treated the concept of "emergency" power differently in the early part of the war.

Here's a page from the Spitfire II manual:

http://img27.imageshack.us/img27/9780/spitfireiirating.jpg

And here's Mike William's entry for the Spitfire II: http://www.spitfireperformance.com/spitfire-II.html

Note the test of the Spitfire II in June 1940 uses only 9 lbs boost.

From that it appears that 12 lbs boost could not be used in the Spitfire II, except for take-off. But in the same manual:

http://img51.imageshack.us/img51/3548/spitfireiiboostcutout.jpg

It was using the boost control cut-out that enabled 12 lbs boost. So the manual doesn't contain an official engine rating, but it does tell pilots how to use 12 lbs.

Likewise, Spitfires were already using 12 lbs boost in combat at the time of the test of Spitfire II. Yet there's no mention of 12 lbs in the test of the Spitfire II, or the Spitfire I they are comparing it against.

Holtzauge
02-06-2010, 04:04 AM
Originally posted by FatCat_99:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Holtzauge:
The Spitfire Mk5 at +16 boost certainly looks like a performer http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

At least on your charts. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif But your charts also show something like 16 seconds for a 360 degree turn for the Mk IX LF at +18, and the Russians measured 18 secs in flight trials.. same as the Mk V btw. So I guess you missed something in your calculations.

I am not sure if the OP was interested in finding good "nominal" specifications for the Mark V, or rather trying to find such for real life, but in either case, the following excerpt from an 1943 British report should be of interest.
</div></BLOCKQUOTE>
Holtzauge numbers might be somewhat optimistic for 16lb at least climb seems to be too good in comparison with the one test at 16lb on spitfireperformanc . On the other hand we don't know much about Russian test, how many test they made with the plane, what was the condition of plane and engine, were they flew plane at optimum speed etc.

NACA F2A3 test is good example how hard is to meassure turn performance, you can find almost 10 seconds ( this is extreme, of course)difference between turn times at same speed.

My goal is to find what would be most representative SpitMkV variants and their performance. So far we can only conclude that 9lb variant is something that should be modeled. For 12lb nobody showed so far any RL document. I only found in 16lb test reference to 12lb as take off setting and special emergency setting prior to itroduction of 16lb.

FC </div></BLOCKQUOTE>

FC, the climb chart I posted was for the weight you asked for: 2960 Kg. The Spitfire Vc test I believe you are refering to at spitfireperformance.com (AA-878) was for W=6965 lb (i.e =3162 Kg).

For 6965 lb I get 3776 ft/min at SL which does not seem that far off from the 3710 ft/min in the test.

What seems strange for the test though, is that the climb rate remains the same as altitude goes up. Normaly, it should increase over altitude as long as the boost is kept, since the ambient temperature goes down leading to a higher charge density and more power. Problem is that we don't have the engine power data that goes together with this test. Usually, the engine power charts for the Merlin 45 I have seen has the engine power going up with altitude up to critical alt. This is the reason my climb chart shown increasing climb rate up to critical alt.

Concerning the turn performance: The figures I posted are with the assumption that Clmax for the Spitfire is 1.36 and the max turn times are assuming that the "corner" between lift limit and power limited turn is used. AFAIK we do not know the test conditions and boost level for the Russian test so I do not know what's behind the figure. Was it done at WEP 5 min limit or 30 min limit....

Having the same assumption for all a/c makes it possible to compare them on the theoretical level. For example, on the Me109 I use Clmax 1.4. Is this to optimistic? I don't know. I have a turn digram for the Me109 from German sources that sets this at Clmax=1.13, not 1.4. Should we use this instead? Seems to me that Il2 (At least looking at the Il2 4.07 compare figures) generally uses something smaller than the Clmax. The Il2 turn digrams also lack the "corner" and are more smooth in the transition between lift- and thrust limited turnrate.

What about IRL? Is it possible to fly up into this corner? Probably this possibility varies from a/c to a/c depending on buffeting and stall charateristics etc....

IIRC then the RAE did a comparison of Me109E and Spitfire Mk1 turn performance using Clmax and produced turn diagrams with a distinct "corner". I think this is a good way to compare on the theoretical level but maybe the Il2 way of smoothing this out is more realistic from a handling viewpoint. Seeing you are working in co-operation with the developers do you have any info on why they modelled it like they did FC, smoothing out the corner and using a Clmax lower than the theoretical?

Finally: I'm happy to see Kurfurst quoting Russian tests data for the Spitfire Mk9. Then let's also use these as a baseline also for the Me109E performance: I believe the Russians peg the Me109E3 turn rate at over 23 s for a 360 degree turn. Does that figure suit you Kurfurst? Or maybe you prefer quoting the Russian test data selectively? http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

Holtzauge
02-06-2010, 04:20 AM
Originally posted by hop2002:
I believe 12 lbs boost was used in the Spitfire V from the start. I think the RAF simply treated the concept of "emergency" power differently in the early part of the war.

Here's a page from the Spitfire II manual:

http://img27.imageshack.us/img27/9780/spitfireiirating.jpg

And here's Mike William's entry for the Spitfire II: http://www.spitfireperformance.com/spitfire-II.html

Note the test of the Spitfire II in June 1940 uses only 9 lbs boost.

From that it appears that 12 lbs boost could not be used in the Spitfire II, except for take-off. But in the same manual:

http://img51.imageshack.us/img51/3548/spitfireiiboostcutout.jpg

It was using the boost control cut-out that enabled 12 lbs boost. So the manual doesn't contain an official engine rating, but it does tell pilots how to use 12 lbs.

Likewise, Spitfires were already using 12 lbs boost in combat at the time of the test of Spitfire II. Yet there's no mention of 12 lbs in the test of the Spitfire II, or the Spitfire I they are comparing it against.

hop2002: Do you have a power altitude chart for the Merlin 45 at +12 boost? So far, all I have been able to find is for +9 and +16 boost.

Wurkeri
02-06-2010, 04:28 AM
Originally posted by FatCat_99:
Holtzauge numbers might be somewhat optimistic for 16lb at least climb seems to be too good in comparison with the one test at 16lb on spitfireperformanc.

I don't find Holtzauge's numbers particularly optimistic. His is getting about same climb rate at +9lbs 3000rpm as measured on the W.3134, about 16,5m/s and the W.3134 did this at 2850rpm.

The Spitfire V tested at +16lbs, the AA.878, was ballasted like 4x20mm armed and was about 200kg heavier and a slower plane than the W.3134 which seem to be the base of Holtzauges analysis.

PM your e-mail.

Kettenhunde
02-06-2010, 05:41 AM
I believe 12 lbs boost was used in the Spitfire V from the start. I think the RAF simply treated the concept of "emergency" power differently in the early part of the war.

It is called a take off rating. It is approved and used for Take Off only. There is no Emergency setting listed in the document you reference.

Many airplanes have a take off rating. My aircraft has a Take Off rating of 29 InHG @ 2600rpm. Once off the ground as soon as permitted, Climb out at 25.5 InHG @ 2600 rpm.

If it is an approved Emergency rating, then it will specifically list it as an Emergency rating along with any restrictions in its use. For example, +12 could be used as an Emergency rating for 5 minutes below 10,500 ft in the Merlin XII at some unknown time period after July 1940.

No guessing, reading into, or speculation required.

This for example listed +12 as an approved:

http://www.spitfireperformance.com/spit2pnfs3.jpg

However the same publication from July 1940 does not list +12 as an Emergency rating for the Merlin XII engine.


I don't find Holtzauge's numbers particularly optimistic.

http://forums.ubi.com/images/smilies/partyhat.gif

hop2002
02-06-2010, 06:19 AM
It is called a take off rating. It is approved and used for Take Off only. There is no Emergency setting listed in the document you reference.

Yes Crumpp, that's the point. It doesn't list an emergency power rating, but elsewhere in the manual tells pilots to operate the boost cut-out to get emergency power.


http://www.spitfireperformance.com/spit2pnfs3.jpg

However the same publication from July 1940 does not list +12 as an Emergency rating for the Merlin XII engine.

No, but it does tell pilots how to get emergency power:

http://img51.imageshack.us/img51/3548/spitfireiiboostcutout.jpg

So do we conclude emergency power wasn't available, when the manual tells pilots to pull the lever to get emergency power?

Or do we conclude that the RAF simply wasn't giving an emergency power rating, even though it was being used in combat?

The Merlin III page you linked to is similar in design and layout to later RAF pilot manuals. In fact, every one of these later manuals lists a combat rating, the earlier ones do not, even on planes like the Spitfire II that actually had boost cut out controls to allow them to use emergency power.

Kettenhunde
02-06-2010, 07:04 AM
Yes Crumpp, that's the point. It doesn't list an emergency power rating, but elsewhere in the manual tells pilots to operate the boost cut-out to get emergency power.

Hop,

The 5 minute limit is PLAINLY listed in the document you posted as +9lbs.

Any speculation about using +12lbs of boost at the time period of the POH you listed is PURE FANTASY.

It is that simple.

IF +12lbs is approved, it will be clearly stated and listed along with any restriction on its use.

No detective work required.

Pilots Operating Instructions are not written so the pilots reads it and wonders how to operate the machine.

There is no question by the POH that 12lbs is not approved at the time period of the document you list. My copy of POH also clearly shows +12lbs was not approved at the time.

FatCat_99
02-06-2010, 07:30 AM
Originally posted by Holtzauge:
FC, the climb chart I posted was for the weight you asked for: 2960 Kg. The Spitfire Vc test I believe you are refering to at spitfireperformance.com (AA-878) was for W=6965 lb (i.e =3162 Kg).
My bad, missed the weight difference.


The Il2 turn digrams also lack the "corner" and are more smooth in the transition between lift- and thrust limited turnrate.

What about IRL? Is it possible to fly up into this corner? Probably this possibility varies from a/c to a/c depending on buffeting and stall charateristics etc....

Seeing you are working in co-operation with the developers do you have any info on why they modelled it like they did FC, smoothing out the corner and using a Clmax lower than the theoretical?
I don't know why they modeled it like that in Il2, I could ask but considering that they are very busy it is faster to figure that out ourself than to wait for answer. IMO their decision is acceptable. Main reason ,IMO, for "corner" is lack of accounting for change in Cl max at different speeds. They probably decided to smooth out the "corner" to compensate for that. Keep in mind that Il2 compare is not very accurate for turn comparison so it might be that human flown plane will have different turn characteristics than shown in Il2Compare.

Can somebody suggest now what should be most representative SpitVb variants in terms of numbers of planes and boost used. Another still open question is 12lb rating, if it was only for take off or 1 min max than there is no point in modeling it but if and when that rating was allowed for at least 3 minutes than we should model it.


FC

suitsu
02-06-2010, 07:47 AM
Hi, gotta say impressed with all the information here, and I'm no expert but would like to add a few points.
Many MKV's were upgraded mkI or II's, and may of these had been crashed and repaired. It was not uncommon for 3 planes to be combined to form a servicable one. The various mks and engine combinations are not set in stone, any combination was used to get aircraft servicable.
When attempting this daunting task of trying to replicate MKV performance, It should be done on an average, and I would say, is nigh on impossible due to the conditions at the time.

hop2002
02-06-2010, 07:50 AM
Hop,

The 5 minute limit is PLAINLY listed in the document you posted as +9lbs.

Any speculation about using +12lbs of boost at the time period of the POH you listed is PURE FANTASY.

It is that simple.

Crumpp, can you explain what this means:

http://img51.imageshack.us/img51/3548/spitfireiiboostcutout.jpg

It is a clear instruction on how to achieve 12 lbs boost in an emergency.

Kettenhunde
02-06-2010, 08:06 AM
The POH instructions are quite clear as to what settings mean. You confuse the instructions on how to physically operate the controls with a engine limit.

http://img14.imageshack.us/img14/2476/smisconception.jpg (http://img14.imageshack.us/i/smisconception.jpg/)

http://img222.imageshack.us/img222/6320/spit29.jpg (http://img222.imageshack.us/i/spit29.jpg/)

JtD
02-06-2010, 08:21 AM
Originally posted by suitsu:
Hi, gotta say impressed with all the information here, and I'm no expert but would like to add a few points.
Many MKV's were upgraded mkI or II's, and may of these had been crashed and repaired. It was not uncommon for 3 planes to be combined to form a servicable one. The various mks and engine combinations are not set in stone, any combination was used to get aircraft servicable.
When attempting this daunting task of trying to replicate MKV performance, It should be done on an average, and I would say, is nigh on impossible due to the conditions at the time.

Welcome to this board. What you say about the various engine combinations I found absolutely true. There probably was a dozen types of Merlins with various boost settings used on the V. Even worse, many of these engines are so very similar (45, 50, 55, for instance) yet not exactly the same. One could probably add 50 variants to the game and still miss an important one.

Kettenhunde
02-06-2010, 08:40 AM
I don't know why they modeled it like that in Il2, I could ask but considering that they are very busy it is faster to figure that out ourself than to wait for answer. IMO their decision is acceptable. Main reason ,IMO, for "corner" is lack of accounting for change in Cl max at different speeds. They probably decided to smooth out the "corner" to compensate for that. Keep in mind that Il2 compare is not very accurate for turn comparison so it might be that human flown plane will have different turn characteristics than shown in Il2Compare.


The IL2 compare shows turn time for 360 at 1 KM not Rate Of Turn doesn't it.

The available angle of bank power on is a U shaped curve. When you factor power effects, our turn performance loses the sharp point.

As a general rule, CLmax turn are minimum radius turns for a given velocity. A little back from CLmax is our maximum load factor turn for that velocity. Some aircraft designs, these points are very close and others not so much.

http://img20.imageshack.us/img20/2357/envelopez.jpg (http://img20.imageshack.us/i/envelopez.jpg/)

http://img20.imageshack.us/img20/8098/spitfiremkixmerlin6618d.jpg (http://img20.imageshack.us/i/spitfiremkixmerlin6618d.jpg/)

http://img442.imageshack.us/img442/4387/typicalpropfighterturnr.jpg (http://img442.imageshack.us/i/typicalpropfighterturnr.jpg/)

Of course, I don't know what the hell I am talking about do I?

edited because my power on/power off diagram is not loading....

Kwiatos
02-06-2010, 10:02 AM
Ok some needed info about SPitfire Mk I, II and V at +12lbs emergency power:

Spitfire MK1 and Merlin III at +12 lbs

http://i50.tinypic.com/21509dd.jpg

http://i50.tinypic.com/pygau.jpg


http://i49.tinypic.com/2llitqh.jpg

Spitfire Mark V

http://i49.tinypic.com/24bp8ph.jpg

Speed:

http://i50.tinypic.com/161m47.jpg

Kettenhunde
02-06-2010, 10:31 AM
The question is when did it occur. The data it occurred is the issue not the fact it occurred. You can clearly see that in June 1942, +12lbs was in use in the Spitfire Mk Vb's as flown by the RAE in the trials of WNr. 313.

Your engine limitations agree with my copy of the July 1940 Spitfire POH.

Clearly +12lbs was not approved for any operations beyond take off as of July 1940.

JtD
02-06-2010, 10:38 AM
Nice info, thanks.

If I was to sum up Merlin 45 performance, would any of the following be wrong or seem unreasonable:
9lb boost: 1030 hp at sea level, 1210 hp at 18000 feet
12lb boost: 1185 hp at sea level, 1335 hp at 15000 feet
16lb boost: 1410 hp at sea level, 1515 hp at 11000 feet.

thefruitbat
02-06-2010, 10:53 AM
Originally posted by Kettenhunde:
The question is when did it occur. The data it occurred is the issue not the fact it occurred. You can clearly see that in June 1942, +12lbs was in use in the Spitfire Mk Vb's as flown by the RAE in the trials of WNr. 313.

Your engine limitations agree with my copy of the July 1940 Spitfire POH.

Clearly +12lbs was not approved for any operations beyond take off as of July 1940.

just an observation, your own chart you posted says

take off max rpm 3000, min rpm 2270 max boost 12lbs
(up to 1000ft <span class="ev_code_RED">or</span> for 3 mins)

http://i7.photobucket.com/albums/y290/thefruitbat1/ScreenHunter_01Feb061800.jpg

that would seem to suggest to me cleared for 3 mins boost at 12lbs...

Daisan1981
02-06-2010, 11:01 AM
http://img43.imageshack.us/img43/2875/685343565.jpg

hop2002
02-06-2010, 11:06 AM
The POH instructions are quite clear as to what settings mean. You confuse the instructions on how to physically operate the controls with a engine limit.

No Crumpp, the manual gives the engine rating as 9 lbs, then tells pilots how to exceed that limit by using the boost control cut-out.

http://img44.imageshack.us/img44/1241/spitfireboostcontrolb.jpg

http://img51.imageshack.us/img51/3548/spitfireiiboostcutout.jpg

This was the instruction for the Merlin II and III:

http://img44.imageshack.us/img44/759/spitfire12lbspa.jpg

So what do you think the instruction on how to use the boost cut out control on the Merlin XII means? On the Merlin II and III it meant over-riding the automatic boost control to allow 12 lbs boost. The Merlin XII was limited to 9 lbs by the automatic boost control. What do you think the automatic boost control cut-out did?

Kettenhunde
02-06-2010, 11:37 AM
then tells pilots how to exceed that limit by using the boost control cut-out.

Of course, he has to exceed the +9lbs setting in order to access the TAKE OFF rating as of July 1940.

I think your missing that entire sentence instructing +12 as the take off position...


just an observation, your own chart you posted says

take off max rpm 3000, min rpm 2270 max boost 12lbs
(up to 1000ft or for 3 mins)

Absolutely, is anyone confused by that? You could fly up to a altitude of 1000 feet or for a maximum of three minutes at +12lbs if you did not go above 1000 feet.

Pretty clear instructions as of July 1940.

The Question is when did +12 get approved and for how long did it operate at +12lbs? We know it was sometime in between July 1940 and June 1942. If you get a July 1943 copy, the Merlin "M" engines could run +18lbs!



Daisan1981

That is a comparison of performance at +9lbs. Very interesting and thanks for posting it.

It is not the ratings used in the RAE tactical trials of WNr 313 for level speed runs.

+12lbs was the rating used in June 1942 by the Spitfire Mk Vb during that test. That document is already posted in this thread.

Kettenhunde
02-06-2010, 11:44 AM
Merlin II and III

Hop,

You are mixing and matching ratings and approvals for different engines. No wonder you are confused.

The Merlin II and Merlin III were not used in production Spitfire Mk V's AFAIK.

At least not according to any of the POH's.

hop2002
02-06-2010, 11:50 AM
Of course, he has to exceed the +9lbs setting in order to access the TAKE OFF rating as of July 1940.

I think your missing that entire sentence instructing +12 as the take off position...

No Crumpp. Firstly, why would they described take-off as an "emergency"?

Secondly, the manual makes no mention of using the cut-out for take-off. It quite clearly states the throttle itself has a take-off position that gives 12 lbs boost.

And thirdly, it's quite clear from the Merlin II and III that the way to achieve 12 lbs boost for combat was to operate the boost control cut-out. The Spitfire II manual makes it quite clear that's the case with the Merlin XII, too.

Kettenhunde
02-06-2010, 11:51 AM
Spitfire MK1 and Merlin III at +12 lbs


Not the Same Engine as the topic of the Spitfire Mk V.....

Kettenhunde
02-06-2010, 11:52 AM
Spitfire MK1 and Merlin III at +12 lbs

Not the same engine as the Spitfire Mk V. You are making the same mistake as Hop.

hop2002
02-06-2010, 12:00 PM
Hop,

You are mixing and matching ratings and approvals for different engines. No wonder you are confused.


No Crumpp, I'm not confused at all. When the RAF increased the ratings on the Merlin II and III and IX, they did so by fitting a control that disabled the automatic boost control, allowing a higher boost pressure. That control was fitted to the Merlin XII, allowing 12 lbs boost, even though the 12 lbs rating wasn't included in the handbook or the A&AEE test.

So the Spitfire II initial test, and the Spitfire II manual, make no mention of 12 lbs boost, despite it being allowed. If that's the case, the absence of any mention of 12 lbs in the initial Spitfire V test, and the Spitfire V manual, do not indicate that 12 lbs wasn't allowed.

Kettenhunde
02-06-2010, 12:20 PM
Here is an unknown context curve dated August of 1941....

Best case, it is the approval and worst case, it is just a preliminary investigation showing possibilities.

http://www.spitfireperformance...tfire-V-raechart.jpg (http://www.spitfireperformance.com/spitfire-V-raechart.jpg)

In June 1941, it was still using +9lbs...

http://www.spitfireperformance.com/w3134.html

In March 1942, it was still using +9lbs on the Merlin 45....

http://www.spitfireperformance.com/aa873.html

We also see a report in April 1942 that shows only +9lbs.

In August 1942 we know the rating was approved as that is used in the RAE trials of WNr 313.

From July to September 1942, the trials for +16lbs were conducted...

http://www.spitfireperformance.com/aa878.html

It looks to me like sometime between April and June 1942 +12lbs was approved for the Spitfire Mk V series. It also looks like +16lbs could not have been approved before September 1942.

So we are looking at ~4-6 months of possible use at +12lbs in 1942.

That is significant IMHO.

Kettenhunde
02-06-2010, 12:24 PM
If that's the case, the absence of any mention of 12 lbs in the initial Spitfire V test, and the Spitfire V manual, do not indicate that 12 lbs wasn't allowed.

No pilot in the world would believe this line of thinking. Airplane maintenance and instructions do not work like that at all.

You cannot tell a thing about the operation of one aircraft type by looking at the the operation instructions of a different aircraft type.


Bottom line, If it was not mentioned specifically, it was not approved engine rating. You don't have to hunt for it, wonder, or play detective. The approved ratings will clearly be listed with no room for interpretation.

The only exception would be the publication of a Technical Order. TO's become a supplement to the POH upon publication and are required to be carried in the aircraft with the aircraft POH and Logbooks. When a new addition of the POH is published, it incorporates all of the TO's that have come out since the last publication date. The new POH supercedes the older version and the copies of the TO's can be thrown out.

hop2002
02-06-2010, 12:31 PM
Crumpp, the automatic boost control limited the boost pressure to 9lbs. The manual explicitly states that.

The aircraft was fitted with a boost control cut-out, to allow higher boost pressures to be used. The manual explicitly states that.

TheGrunch
02-06-2010, 12:45 PM
I think that whether the pilot was prepared to exceed the limit in the handbook rather depended upon the pilot. Dowding bemoaned the fact that pilots would select the +12lbs boost setting at the slightest provocation at the height of the Battle of Britain. In the Spitfire II Pilot's Notes the engine limitations were clearly stated to be exactly the same as those in the Spitfire Mk. V handbook, +12lbs (takeoff or 3 minutes) and +9lbs (5 minutes), yet pilots regularly exceeded +9lbs in combat if you read pilot accounts.

Kurfurst__
02-06-2010, 12:57 PM
Originally posted by hop2002:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Hop,

You are mixing and matching ratings and approvals for different engines. No wonder you are confused.


No Crumpp, I'm not confused at all. When the RAF increased the ratings on the Merlin II and III and IX, they did so by fitting a control that disabled the automatic boost control, allowing a higher boost pressure. That control was fitted to the Merlin XII, allowing 12 lbs boost, even though the 12 lbs rating wasn't included in the handbook or the A&AEE test.

So the Spitfire II initial test, and the Spitfire II manual, make no mention of 12 lbs boost, despite it being allowed. If that's the case, the absence of any mention of 12 lbs in the initial Spitfire V test, and the Spitfire V manual, do not indicate that 12 lbs wasn't allowed. </div></BLOCKQUOTE>

Nice theory, but it is still against documentary evidence.. IMHO its pretty clear from the papers that the initial rating was +9 lbs for the Mk I/II, and +12 was only a takeoff rating up to a limited altitude, pretty much like the special 1.40/1.45ata take off boost on DB 601A/Aa. You should find and present a paper that shows the +12 rating allowed for "All out level"; the present ones clearly show it was not the case in March 1940, but it was increased around June/July. I mean, you can choose to believe any other fantasy, but even to you it is clear there's nothing solid to base your opinion on, except that you always wish for more for the RAF than what was there... http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Now as far as the Mk V / Merlin 45 ratings go, these are also homogenously show a +9 lbs early boost limit, which was, sometime later, we do not know when increased to +12 lbs, and the in August 1942, to +16 lbs.

Kurfurst__
02-06-2010, 12:59 PM
Originally posted by hop2002:
Crumpp, the automatic boost control limited the boost pressure to 9lbs. The manual explicitly states that.

The aircraft was fitted with a boost control cut-out, to allow higher boost pressures to be used. The manual explicitly states that.

Hi,

it also explicitly says that nothing above +9 lbs may be used in all out level flight, above 1000 feet, or for more than 3 minutes.
You seem to repeatadly miss that part. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Kwiatos
02-06-2010, 01:46 PM
Originally posted by TheGrunch:
I think that whether the pilot was prepared to exceed the limit in the handbook rather depended upon the pilot. Dowding bemoaned the fact that pilots would select the +12lbs boost setting at the slightest provocation at the height of the Battle of Britain. In the Spitfire II Pilot's Notes the engine limitations were clearly stated to be exactly the same as those in the Spitfire Mk. V handbook, +12lbs (takeoff or 3 minutes) and +9lbs (5 minutes), yet pilots regularly exceeded +9lbs in combat if you read pilot accounts.

Exacly even it is not cleared in manual for Spitfire MK1, MK2 or MK5 for +12lbs emergency power we clearly know that pilots could and used +12 lbs by cut out automatic bost control.
And it could be used not only up to 1000ft ( like take off power) but was effective to used up to 10 000 or 11 000 ft depend of Merlin type ( III, XII or V)

hop2002
02-06-2010, 02:23 PM
Hi,

it also explicitly says that nothing above +9 lbs may be used in all out level flight, above 1000 feet, or for more than 3 minutes.
You seem to repeatadly miss that part.

Actually Kurfurst I pointed out that part in my first post.

The engine rating was for 9 lbs. The pilot's handbook then tells the pilot to pull the boost control cut-out lever to exceed that rating.

The whole point is that the Spitfire II manual, and it's first test by the RAE, show a maximum of 9 lbs. Yet the pilots were instructed how to exceed that.

Look again at the test of the Spitfire II on Mike's page. From that test:

Consequent upon this and the increase in power of the Merlin XII over the Merlin III below full throttle height the aeroplane is about 6 - 7 miles per hour faster at heights less than 17,000 feet and about 4 - 8 m.p.h. slower at heights above 20,000 feet. It should be noted that though the boost pressure on the Merlin XII is +9 lb. per sq.inch as against +6 1/4 lb. per sq.inch on the Merlin III there is little difference in the engine power at heights of 16,000 feet and above.

The Spitfire I was tested at 6.25 lbs, the Spitfire II at 9 lbs. The test was carried out in June 1940, at a time when the Spitfire I was already using 12 lbs in combat squadrons, with full approval from the air ministry.

The contention from some is that 12 lbs wasn't used in the Spitfire V until some time in 1942 because a page from the manual, and early performance tests, don't mention 12 lbs boost. But that's exactly the case for the Spitfire II, which we know did use 12 lbs boost.

JtD
02-06-2010, 02:32 PM
I think it is quite likely that combat pilots would rather deal with an angry mechanic and an upset superior than with a bandit at 6 o'clock.

Since it was technically possible on the Spitfire, I'd figure that pilots would use 12lb boost in case of emergency - be it cleared or not. A pilot account of a Spitfire V (Merlin 45) pilot would come in handy.

The date at which the 12lb boost were cleared for take off would also be neat to see.

Kwiatos
02-06-2010, 02:40 PM
It was not only technicaly possible to use +12lbs in war emegency power but was also officaly permited - for Merlin III in 20.3.1940 !

http://www.wwiiaircraftperformance.org/ap1590b.jpg

http://www.wwiiaircraftperformance.org/hurricane/hurricane-12lbs-14nov39.jpg

Holtzauge
02-06-2010, 02:50 PM
Thanks for all the data Kwiatos!

I will look all this over tomorrow and see if I have enough engine power/altitde data to update the calculations for +12 boost as well.

Holtzauge
02-06-2010, 02:53 PM
Originally posted by JtD:
Nice info, thanks.

If I was to sum up Merlin 45 performance, would any of the following be wrong or seem unreasonable:
9lb boost: 1030 hp at sea level, 1210 hp at 18000 feet
12lb boost: 1185 hp at sea level, 1335 hp at 15000 feet
16lb boost: 1410 hp at sea level, 1515 hp at 11000 feet.

JtD, maybe I missed something obvious (I see the 1185 hp at SL in Kwiatos data) but how did you arrive at the 1335 hp at 15000 ft?

Kettenhunde
02-06-2010, 02:58 PM
Spitfire Mk. V handbook

The Spitfire Mk V POH copy I have clears it to +18lbs for certain engine types.

In this case the Merlin 45(M), 50(M), and 55(M), series engine was cleared to +18lbs by February 1943.

The Merlin II and Merlin III engines found in the Spitfire Mk I have nothing to do with the Merlin 45,46,50, and 55 series found in the Spitfire Mk V series.

Just as the Spitfire Mk II series Merlin XII engine is a completely different engine with different instructions.


in August 1942, to +16 lbs.



It seems confusing but the trials of WNr 313 were completed in late August 1942. At that time, +16lbs trials were underway and as the report was finished in September 1942.

http://www.spitfireperformance.com/aa878.html

If you notice the stamp on the RAE report, it was the privy of the Ministry of Aircraft Production to make the decision and take the action to increase the operational limits of the aircraft.

Aircraft maintenance and technical changes are very strictly regimented. Alterations to the aircraft have to be documented, instructions disseminated not only to pilots but maintenance personnel as well. It is not a year long process but it is not an overnight one either.

There will be a period of lag time between the issuance of an order and its appearance in the operational units. I would be very surprised to see Operational approval in August of 1943 considering the trials were not complete.


I think that whether the pilot was prepared to exceed the limit in the handbook rather depended upon the pilot. Dowding bemoaned the fact that pilots would select the +12lbs boost setting at the slightest provocation at the height of the Battle of Britain.

Correct, he berates them for the frequency in which they select an approved rating in the Spitfire Mk I's Merlin II and III engines.

Don't confused using what is approved to often with using something that is not approved.

Again nothing to do with the Spitfire Mk V or the Merlin 45, 46, 50, 55 series engines used in it.

So we don't have any evidence of any pilots exceeding published limits but rather just a commander saying "quit using the limit so much."


In the Spitfire II Pilot's Notes the engine limitations were clearly stated to be exactly the same as those in the Spitfire Mk. V handbook, +12lbs (takeoff or 3 minutes) and +9lbs (5 minutes), yet pilots regularly exceeded +9lbs in combat if you read pilot accounts.

Once again, the Spitfire Mk II uses the Merlin XII engine while the Spitfire Mk V uses the Merlin 45, 46, 50, 55 series engines.

Although they might share some common components, they are different engines with different operating instructions.

All instructions are specific and apply to that engine listed. You cannot apply them to any other circumstances.

This is common. The BMW801D2 had seven different variants and each was unique.

The Lycoming O-360 has over 167 variants but only 12 different prefixs.

If you put the specified fuel for an O-360 B1A into and O-360 A1A you will destroy the motor.

Both are Lycoming O-360's and both have totally different operating instructions as well as limits.

For some reason, people want to think all Merlin engines are the same and everything published applies to them all equally. It just does not work that way.

Holtzauge
02-06-2010, 03:04 PM
Originally posted by FatCat_99:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Holtzauge:
FC, the climb chart I posted was for the weight you asked for: 2960 Kg. The Spitfire Vc test I believe you are refering to at spitfireperformance.com (AA-878) was for W=6965 lb (i.e =3162 Kg).
My bad, missed the weight difference.


The Il2 turn digrams also lack the "corner" and are more smooth in the transition between lift- and thrust limited turnrate.

What about IRL? Is it possible to fly up into this corner? Probably this possibility varies from a/c to a/c depending on buffeting and stall charateristics etc....

Seeing you are working in co-operation with the developers do you have any info on why they modelled it like they did FC, smoothing out the corner and using a Clmax lower than the theoretical?
I don't know why they modeled it like that in Il2, I could ask but considering that they are very busy it is faster to figure that out ourself than to wait for answer. IMO their decision is acceptable. Main reason ,IMO, for "corner" is lack of accounting for change in Cl max at different speeds. They probably decided to smooth out the "corner" to compensate for that. Keep in mind that Il2 compare is not very accurate for turn comparison so it might be that human flown plane will have different turn characteristics than shown in Il2Compare.

Can somebody suggest now what should be most representative SpitVb variants in terms of numbers of planes and boost used. Another still open question is 12lb rating, if it was only for take off or 1 min max than there is no point in modeling it but if and when that rating was allowed for at least 3 minutes than we should model it.


FC </div></BLOCKQUOTE>

OK, if we go with the Clmax limit in Il2 that's fine. I do not necssarily question their decision to do what they did because I have no other data than Clmax and perhaps there is a very good reason to limit this the way they have done. Maybe we will find out, maybe not.

However, I do think it would be good to understand how this is done inthe code. Is it a given percentage of the Clmax across the board e.g. 80-90% or is it individually tuned for each a/c?

Can you find out what the limits are used for Spitfire and Me109 in the code? If you do, then I can update the C++ calculations to use this instead (for the purpose of providing input to the mods that is).

Kurfurst__
02-06-2010, 03:40 PM
Originally posted by hop2002:

The contention from some is that 12 lbs wasn't used in the Spitfire V until some time in 1942 because a page from the manual, and early performance tests, don't mention 12 lbs boost. But that's exactly the case for the Spitfire II, which we know did use 12 lbs boost.

Well, have you got any examples of +12 lbs boost mentioned for the Spitfire Mark V? I mean, in 1941 etc, or at some early date? Because as you say we do have evidence for the Mark I and Mark II that they were cleared for +12 later on, probably very soon after they were cleared only for +9 lbs (I mean, in normal level flight at practical altitudes). Why dont we have anything at all for the Spitfire Mark V? Why are all test we know are for +9 lbs? Why are all early Merlin 45 engine curves we know show only +9 lbs ratings..? etc.

I mean if +12 lbs would have available from the start, there should be at least some evidence for it.

Kurfurst__
02-06-2010, 03:42 PM
Originally posted by Kwiatos:
And it could be used not only up to 1000ft ( like take off power) but was effective to used up to 10 000 or 11 000 ft depend of Merlin type ( III, XII or V)

It depends on the timeframe. Early manuals and engine sheets clearly limit the use of +12 lbs for 1000 feet, ie. used for take off purposes only.

Kwiatos
02-06-2010, 03:52 PM
Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kwiatos:
And it could be used not only up to 1000ft ( like take off power) but was effective to used up to 10 000 or 11 000 ft depend of Merlin type ( III, XII or V)

It depends on the timeframe. Early manuals and engine sheets clearly limit the use of +12 lbs for 1000 feet, ie. used for take off purposes only. </div></BLOCKQUOTE>

All these manuals ( SPit MK1, MKII, MKV) show only take off rating +12 lbs up to 1000 ft or 3 minutes rating.

But we see at the others documents (showed here) that +12 lbs was allowed for emergency combat rating (not only take off) for short peroid of time. It was used not only up to 1000ft but was effective up to about 10000 - 11000 ft depend of type of engine. Just see posted documents above.

Kwiatos
02-06-2010, 04:01 PM
And also such one from 25.8.1941 http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

http://www.spitfireperformance.com/spitfire-V-raechart.jpg


http://img268.imageshack.us/img268/2876/pro190surveyc1.jpg


I have not seriously doubts that combat emergency rating +12lbs was used in
Spitfire MK V from beginig the same like with previous Mark and Merlin engines since used 100 octan fuel.

Kettenhunde
02-06-2010, 05:35 PM
And also such one from 25.8.1941

That proves absolutely nothing....

Want to see a FW-190A curve for 700kph (+) performance?

Want to see some 2000(+) hp curves from BMW in 1942 on the FW-190?

Wanna see the performance of the FW-190 with a Turbocharger in 1943?

Want to see a curve for FW-190B series in 1941?

All predictions of things to come or that did not come to pass....

If is not in the POH, it was not approved.

JtD
02-06-2010, 11:33 PM
Originally posted by Holtzauge:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
Nice info, thanks.

If I was to sum up Merlin 45 performance, would any of the following be wrong or seem unreasonable:
9lb boost: 1030 hp at sea level, 1210 hp at 18000 feet
12lb boost: 1185 hp at sea level, 1335 hp at 15000 feet
16lb boost: 1410 hp at sea level, 1515 hp at 11000 feet.

JtD, maybe I missed something obvious (I see the 1185 hp at SL in Kwiatos data) but how did you arrive at the 1335 hp at 15000 ft? </div></BLOCKQUOTE>

I have only three data points - 9 lb at altitude, 12 lb at sea level and 16 lb at altitude again. From the general engine performance of the Merlin I know that it gains about 100hp per 10000ft of altitude, so I put that on a sheet of paper, the diagram looked alright and got the result as written down above. It could vary a bit, maybe 1345 hp, but it should not be far off. Since it is a calculation, I was asking for confirmation.
I agree with the opinion you voiced a couple of posts ago - with a power chart like that a performance as tested by the British is not possible.

JtD
02-06-2010, 11:41 PM
Kwiatos, thanks for laying out your arguments for the 12lb, like I said I don't consider practices with other Merlin engines definite proof, but Fw document is definite proof that 12lb were being used as WEP at least for some time.
So we have a lot of "likely" and one "definitely" argument.

Kettenhunde
02-07-2010, 07:08 AM
Well, have you got any examples of +12 lbs boost mentioned for the Spitfire Mark V?


Just the one I posted on page 5 as part of the WNr 313 RAE trials and Kwiatos re-posted above.

Using that as a known point, we can get an idea of the time period it was used.

I started constructing a time line. If anyone else has info feel free to add to it.


It looks to me like sometime between April and June 1942 +12lbs was approved for the Spitfire Mk V series. It also looks like +16lbs could not have been approved before September 1942.

So we are looking at ~4-6 months of possible use at +12lbs in 1942.

http://forums.ubi.com/eve/foru...041046038#4041046038 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/4441054928?r=4041046038#4041046038)

thefruitbat
02-07-2010, 07:41 AM
umm, that document above that kwiatos posted is dated August 18th 1942, and clearly states the "spitfire VB has since been cleared for 3000RPM @ 16lbs boost"

This means that 16lbs was cleared sometime between the tests being flown, and the document being written, on the 18th august. so sometime before august 18th...

August quite clearly comes before September...

JtD
02-07-2010, 08:25 AM
They were testing the 16lb boost for performance gains in July already. According to the objective of the test, it was to determine the performance of the 16lb that "are now permitted". So that puts the 16lb to July at latest.

It was tested after the clearance for service had already been given, just like the 18lb boost in the M engines.

Kettenhunde
02-07-2010, 09:03 AM
August quite clearly comes before September...

Yes it does....

The trials for +16lbs were clearly not finished in August!

That is a very powerful stumbling block for any speculation on the Operational Squadrons using +16lbs before then.

The testing was conducted from July to September 1942 and the report not filed until 25 November 1942.

It is not the call of the RAE to put out to the force operational limitations. The RAE investigates and makes recommendations to the Ministry of Aircraft Production. They are the ones who publish all technical changes and specifications.

http://img705.imageshack.us/img705/6683/16lbstest.jpg (http://img705.imageshack.us/i/16lbstest.jpg/)

Since both reports, the +16lbs trials and WNr 313, are done at the same time period by the same agency, it seems probable that the comment is based on input from fellow RAE members "across the hall" and not based on published specifications being used in the force. Remember, the RAE cannot authorize or release clearance for any technical changes to the aircraft.

These trials were done from the same airfield probably by many of the same people.

The other possibility the Ministry of Aircraft Production said, "Yeah ok it works, we will take all the responsibility if people start dying and go ahead an approve it without all the information."

Could that have happened? Ehh, Maybe...it was war but you are not doing your side much good if consequences of the decision went the other way and an unforeseen issue like that encountered with 100/150 grade started killing pilots or destroying airplanes. It represents a big gamble and one I would be very surprised if it was made.

The only definitive proof is clearance in the POH or a copy of the published Technical Order Addendum's included in every POH:

http://img707.imageshack.us/img707/4892/spit03.jpg (http://img707.imageshack.us/i/spit03.jpg/)

In this POH, from February 1943, ~3 months after the file date of the +16lbs trials, we have +16lbs included in the limitations.

http://img205.imageshack.us/img205/7518/spit19.jpg (http://img205.imageshack.us/i/spit19.jpg/)

Kurfurst__
02-07-2010, 09:14 AM
IIRC the +16 lbs rating was cleared sometimes around August 1942, there was memo regarding how to fight the fw 190, and it notes the clearance of +16. But I have to check at home.

Kettenhunde
02-07-2010, 09:40 AM
I got it, It is from the Air Ministry not the Ministry of Aircraft Production and is dated August 1942.

The information contained in the RAE trials was sent to the MAP on 13 August 1942.


The performance results at normal rating have been forwarded to M.A.P. (D.D.T.D.) by letter ref: AAEE/4493/-A.S. 56/18 and A.S.56/42 dated 13th August, 1942.

http://www.spitfireperformance.com/aa878.html


So we have orders out the last few days in August 1942....

Good! That solves that, IMHO.

hop2002
02-07-2010, 09:50 AM
Yes, one of the Pilot Prune guides. Dated August 1942:


Spitfires are now modified to give +16 emergency boost. It must be impressed on pilots that this gives a great increase of speed under 21,500 feet and 18,250 feet for Merlin 46 and 45 engines respectively, and that if used for combat only, there is no risk of engine failure

When hard pressed you can fly +16 boost and 3,000 revs. without any danger of blowing up (it then goes on to warn about fuel consumption at 16 lbs boost)

Air Tactics (Air Ministry)
August 1942

Kettenhunde
02-07-2010, 10:17 AM
There is no danger of the engine blowing up if the POH instructions are followed.....

thefruitbat
02-07-2010, 10:44 AM
what part of 'has since been cleared' and 'are now permitted' is so hard to understand. Are you suggesting that the documents saying these things are wrong??? How can you misconstrue these comments???

They were still testing vb's at 9lbs boost long after the vb was in service flying at at least that boost, as lots of your posts have quite pointedly shown,

as JTD said,


It was tested after the clearance for service had already been given, just like the 18lb boost in the M engines

By the way, you are aware of the tactical situation that faced the RAF in 1942 i assume, or is that a mistake on my part.

good to see you revised your 'could not have been approved before September 1942' to august though...

Either way, this is largly irelevant for this thread now, as it has now been proved that the spit Vb WAS flying at 12lbs, 16lbs for merlin45 and 18lbs for the merlin45m engines through various times in 1942 and quite possibly 12lbs for merlin45 in '41, which was the info that fatcat was looking for, for modelling spits in the game...

@Fatcat, will you be addresing the problem of the wings appearing to low when viewed from inside the cockpits of the Vc models?

Kettenhunde
02-07-2010, 03:59 PM
good to see you revised your 'could not have been approved before September 1942' to august though...


LOL...

You mean a few days in August 1942.

The report clearly says September but the key information being released on 13 August to the MAP.

So you think RAF Spitfire Mk Vb's were in the air fighting Jerry on the 14th of August using +16lbs???

Come on get real. Not only do the changes to POH have to be drafted but there is the maintenance side of the house that has to publish the procedures for clearing the aircraft to use the boost.

It wasn't a phone call, "OK boys, push the throttle even harder and you will get +16lbs".

At minimum adjust have to be made to the cables to extend them! Assuming no other changes or adjustments are required.

If they got the information in the middle of August, that gave them two weeks until the end of the month. That is was done in such a short time is telling.

Here is an example of a Service Bulletin...

http://www.aopa.org/whatsnew/r...ytheon_sb27-3358.pdf (http://www.aopa.org/whatsnew/regulatory/raytheon_sb27-3358.pdf)

thefruitbat
02-07-2010, 04:26 PM
nowhere in my posts did i say or talk about when operational use started...

i just dissagreed with what YOU said, which was 16lbs 'could not have been approved before September 1942', as clearly it had been approved before, in august.

feel free to keep putting words in my mouth if it makes you feel better.

Kettenhunde
02-07-2010, 08:00 PM
i just dissagreed with what YOU said, which was 16lbs 'could not have been approved before September 1942', as clearly it had been approved before, in august.

You have taken a part of my statements and focused on it out of context to completely change the meaning of what I wrote.

I do not know and if I did I would have said so long ago with the evidence.

I said the evidence presented was not likely. That was because I did not read the part about sending the results to the MAP on 13 Aug 1942. That statement was included in the report because that is a very unusual thing to do.


Crumpp says:
That is a very powerful stumbling block for any speculation on the Operational Squadrons using +16lbs before then.


Crumpp says:
Could that have happened? Ehh, Maybe...it was war but you are not doing your side much good if consequences of the decision went the other way and an unforeseen issue like that encountered with 100/150 grade started killing pilots or destroying airplanes. It represents a big gamble and one I would be very surprised if it was made.


Crumpp says:

From July to September 1942, the trials for +16lbs were conducted...

http://www.spitfireperformance.com/aa878.html

It looks to me like sometime between April and June 1942 +12lbs was approved for the Spitfire Mk V series. It also looks like +16lbs could not have been approved before September 1942.

http://forums.ubi.com/eve/foru...041046038#4041046038 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/4441054928?r=4041046038#4041046038)

Being that is was late August 1942, I would be surprised if any operational squadrons were using it before September.

You do realize you are only talking a few days difference here?

JtD
02-07-2010, 11:42 PM
The A&AEE often tested planes after they were cleared for service. Usually to validate manufactures claims. For instance, while the 18lbs for the LF were clear in February 1943, they didn't test one until April 1943. So no worries, Fruitbat. That fact speaks for itself.

---

The question has been brought up if the 9lb boost were ever used without the 12lb take off boost. It was my understanding that the Merlin 45 was introduced with just 9lb initially, the 12lb take off boost being cleared only thereafter. But then I've not been able to find evidence for that. Question into this very knowledgeable circle: Who's got something to prove or disprove that? I think an early 1941 pilots manual would do the trick.

p.s. In the earliest test on of the SpitV on spitfireperformance.com you can see a take off run of 330 yards, as opposed to the around 250 you'll usually find for 12lb boost, so that's why I thought it was a 9lb run. It could still be that long for other reasons or it could be they simply didn't use 12 lb in the test while it was already cleared for service. So that's not definite.

Kettenhunde
02-08-2010, 06:13 AM
The A&AEE often tested planes after they were cleared for service.

The RAE and A&AEE are two different organizations with different mission sets.

Your statement is like saying NASA does not comply with FAA Part 61 rules when it does research.

Since NASA violates Part 61, I guess I can too??

http://forums.ubi.com/images/smilies/disagree.gif

Of course not. These organization work closely together. In fact, the Space Shuttle has an FAA airworthiness certification. Anytime NASA does experimental work, it is the FAA who clears the airspace, issues the experimental airworthiness certification, and assist's to ensure the safety as well as progress of the venture.

The RAE, A&AEE, and MAP all work together. What they are doing does not necessarily apply to the operational squadrons on the same time line. It takes time to publish information, disseminate it, and enact the results. With aircraft, every aspect of maintenance and operations is very tightly regimented and controlled.

DrHerb
02-08-2010, 06:21 AM
Zeno's has a POH for the Spit MKII but its dated 1940. Probably too early for this discussion, but Ill throw it out there anyway. Page 13 has engine limit notes.

http://www.zenoswarbirdvideos....spit/Spit2Manual.pdf (http://www.zenoswarbirdvideos.com/Images/spit/Spit2Manual.pdf)

Kettenhunde
02-08-2010, 06:35 AM
POH for the Spit MKII but its dated 1940.

It is hand typed copy dated July 1940, the same as this one:

http://img99.imageshack.us/img99/2262/spit04.jpg (http://img99.imageshack.us/i/spit04.jpg/)

But I noticed the Section II listing engine limitations is dated June 1940.

I think we can say the Merlin XII engine was cleared in July 1940. Probably even a few weeks sooner as generally a Technical Order will come out before the POH is amended.

I would be more comfortable saying that with an actual copy of the manual.

I say that because Zeno has gotten fed some whoopers by gamers in the past.

For example, this P38 dive sheet came off Zeno's site:

The red underlining is mine, the erased text is how it was posted...

http://img20.imageshack.us/img20/1954/p38divelimits.jpg (http://img20.imageshack.us/i/p38divelimits.jpg/)

Here is the actual page from the POH:

http://img12.imageshack.us/img12/6282/p38jdiveplacard.jpg (http://img12.imageshack.us/i/p38jdiveplacard.jpg/)

Kurfurst__
02-08-2010, 07:28 AM
Regarding the question of boost limitations and clearances for the Merlin 45 series.

1,

Merlin XLV / 45 power curve. Note that the highest rating shown is +9 lbs, while Merlin III etc. is shown with a limit of + 12. So obviously the early rating was +9 lbs bosst.

http://i38.photobucket.com/albums/e133/Kurfurst/Aero%20Engines/Merlinpowercurves.jpg

2, Merlin 45 etc. clearance for + 16 lbs boost, July 1942. (probably via Neil Stirling.)

http://i38.photobucket.com/albums/e133/Kurfurst/Aero%20Engines/Merlin45-plus16.jpg

thefruitbat
02-08-2010, 09:20 AM
interseting info Kurfurst,

It does indeed look like the early rating was 9lbs boost, although that graph is bloody hard to read, lol!

This does lead to the question, when was 12lbs introduced, as there seeems to be little documentation of this floating around. It obviously was used, as it is shown in the comparison between the FW190 and the spit mkVb, dated august 18th, 1942.

Its interesting to note the observation of JTD about the earlist test of the Spit MkVb on spitfireperformance, and the long take off run of 330yards as opposed to around 250 for the 12lbs boost for take off tests. Could this be used as an indication, although obviously not proof?

As to the 16lbs boost, the document posted by kurfurst dated 21/7/42, says 'shall be introduced immediatly for application to fighter aircraft' http://forums.ubi.com/images/smilies/partyhat.gif



I have a question regarding Spit MkVb's that i'm hoping someone here can answer, regarding Miss Shilling's orifice.

From sources i've read, it was fitted as standard from march '41, and by june mostly retrofitted.

My question is, how effective was it, the sources i've read say that it 'partially solved' the neg G cutouts, but this was not completly solved until the advent of the SU carb in the merlin 50 (essentially a merlin 45 but with the SU carb), sometime around april/june 1942 (it was certainly present in the Spit MkIX flying operationally from 6thjuly'42.)

Can anyone shed any light on what 'partially solved' means, with regards to actuall flight conditions? Should the spits modelled before the SU carb, have some sort of neg g cutout, although not as prenouced as say the I16's we have in game? This also applies to the hurris we have, as the same 'fix' was applied.

fruitbat

Kettenhunde
02-08-2010, 09:44 AM
Great find Kurfurst.

Notice it gives some of the details for modifying the engines, ie sparkplugs and references boost cut out modifications.

If they have the required sparkplugs, it is very likely that the other technical information is already done.

I would be surprised if on another page of that document it references by document number were to locate the specific instructions for modifying the boost cut out.

I am willing to bet this memo is from the MAP to the RAE clearing them to modify the aircraft to begin the trials which started in July 1942.

Since the RAE trials began in July 1942 this just standard for any aviation regulatory body for anyone who is conducting experimental testing. Your request to conduct the testing must first be reviewed by them and they approve the technical changes.

This is typical of the strict regimentation of aircraft maintenance.


From July to September 1942, the trials for +16lbs were conducted...

http://www.spitfireperformance.com/aa878.html

I don't think it is an approval for Operational Use.

badatflyski
02-08-2010, 09:56 AM
Can anyone shed any light on what 'partially solved' means, with regards to actuall flight conditions? Should the spits modelled before the SU carb, have some sort of neg g cutout, although not as prenouced as say the I16's we have in game? This also applies to the hurris we have, as the same 'fix' was applied.

fruitbat

Yes, indeed. the merlin engine in il2 are all using "injection" instead of carb, or float-carb. (just like the BMW 801 is a carb engine in il2! )

Even the SU carb on M61 did not resolve completly the Neg G effect on engine fuel intake (see RAF comparaison test with FW190).

the first M50 spit's MKVb were build second half of april42..actually, there were only 3 spits MK5B with this engine, 2 of them relabelled LF5b and LR5b, the last beeing a simple mk5b.

JtD
02-08-2010, 10:00 AM
Two nice documents there, Kurfürst. Thanks for posting.

My guess regarding the neg g behaviour is that the engine would not immediately stall, but would do so eventually. In 1943 you still have the advice to do a barrel roll with enough stick to keep the engine running...

VW-IceFire
02-08-2010, 10:52 AM
Sorry if this takes us off the track a tiny bit but I've been wondering with all of this discussion going on...

Spitfire V's were very common until mid 1944. If you take a typical 1943 MTO scenario and pit a Spit Vc tropical against a Bf109G-2... that Spitfire has a huge disadvantage in nearly every way except turn. The MC.202 is somewhat superior as well. Would a 1943 Vc perform that much better? I'm curious.

hop2002
02-09-2010, 05:20 AM
t does indeed look like the early rating was 9lbs boost

I'd be interested to see the date on that chart Kurfurst posted.

As to when 12 lbs was introduced on the Merlin 45, we have direct evidence, a letter from the Ministry of Aircraft Production, Jan 1942, detailing which engines require 100 fuel:

http://img97.imageshack.us/img97/454/merlinratings2.jpg

54" = 12 lbs boost.

FatCat_99
02-09-2010, 05:38 AM
First of all I want to thank everybody who participated in this thread, it was very informative. Can we say now that we need all 3 of MkV max. boost levels represented?
That way 9lb would cover 1941, 12lb for early 1942 and 16lb for late 1942 and 1943.

FC

thefruitbat
02-09-2010, 05:46 AM
i know this is probally stretching things a bit, but is there anyway you can do something with the neg g cutout, like delaying it for a few seconds before it kicks in, to simulate miss shillings orifice for the 1941, and early 42 spits moddeled, as they don't have direct fuel injection, untill the merlin 50 in april 1942.

Also do you have any plans to model the higher altitude rated merlin 46, as we don't have one of them at the moment?

cheers fruitbat

hop2002
02-09-2010, 05:49 AM
Can we say now that we need all 3 of MkV max. boost levels represented?
That way 9lb would cover 1941, 12lb for early 1942 and 16lb for late 1942 and 1943.

I don't think 9 lbs does cover 1941. The MAP document says the Merlin 45 was using 12 lbs boost from the start. We don't have any direct evidence it wasn't.

What we really need is an early Spitfire V manual to see what the ratings were, and to see whether the boost control cut-out was fitted to allow 9 lbs to be exceeded.

Kettenhunde
02-09-2010, 05:56 AM
as they don't have direct fuel injection, untill the merlin 50 in april 1942.


They never had direct fuel injection on any merlin engine.

Throttle body injection is not the same.

All of the German fighter engines were direct fuel injected. None of the Allied engines were direct fuel injected.

thefruitbat
02-09-2010, 06:19 AM
i stand corrected.

makes no difference to what i was asking for though. as far as the game goes it will lead to not having neg g cutout, which is how all the spits are at the moment...

I'm asking for the neg g to be moddeled before the merlin 50, as before the su carb they didn't have throttle body injection, but with a few seconds grace to simulate miss shillings orifice...

happy?

Kettenhunde
02-09-2010, 06:25 AM
i stand corrected.

No problem at all. It does not make any difference to what you where asking.

It is a very important distinction to make though as direct fuel injection is unique and offers many advantages over any other type of fuel metering system.

It is also the most complicated and technically challenging method of fuel metering.

Maybe your next generation game will model the differences. If you want to model airplanes you have to include flying them. I flew halfway to Florida last week pulling carburetor heat every 15-20 minutes as my EIS kept alarming for ice.

http://www.grtavionics.com/pro...ductno=2&featureno=9 (http://www.grtavionics.com/product.aspx?productno=2&featureno=9)

For example, TBI is subject to carburetor icing while direct injection is much more resistant and only subject to intake icing. TBI has both carb heat and alternate air while DI has just has alternate air.

http://www.aircraftspruce.com/...arburetorheatbox.php (http://www.aircraftspruce.com/catalog/eppages/carburetorheatbox.php)

Having Carburetor icing in the middle of a dogfight is not good. Pulling the carb heat feeds heated air into the carburetor. Hot air reduces the power your motor can produce and the slugs of water the engine ingests as the ice melts do not help power either. The engine will skip and run rough until the ice clears and produce less power until carb heat is removed.

Alternate air bypasses the aircraft's intake. This is cold air and does not effect the power of the engine.

Direct fuel injection gets more power for the same amount of fuel with lower CHT and higher EGT on average. That means more power for less wear on less fuel.

You know the load factor limits already.

thefruitbat
02-09-2010, 06:55 AM
interesting info, thanks.

Viper2005_
02-09-2010, 10:41 AM
Fuel injection into the eye of the supercharger allows the evaporation of the fuel to reduce the temperature rise in the supercharger. This is worth about 25 K for a stoichiometric mixture IIRC, and in addition to lowering the charge temperature it also reduces the supercharger work.

Genuine direct injection sacrifices this advantage in exchange for superior fuel metering to individual cylinders, which mainly serves to improve fuel economy (especially at less than full power, where mixture distribution tends to deteriorate).

So it's not just a case of saying that one is better than the other. If you were to design an engine today then you'd almost certainly go for genuine direct injection because we're better at turbomachinery than they were in the 1940s and could therefore get quite a lot of the charge temperature reduction back simply from increased supercharger isentropic efficiency.

So there would be an incentive to go for direct injection in order to grab the SFC benefit. But with 1940s technology, I don't think that you can fault RR's approach.

http://www.wwiiaircraftperform...g/merlin-lovesey.pdf (http://www.wwiiaircraftperformance.org/merlin-lovesey.pdf)

BTW, IMO the "clipped, cropped and clapped" Spitfire Vs are worthy of attention; their +18 psi rating makes for an interesting comparison with the later Spitfire IX, and potentially allows for some interesting fights with early Fw190s(especially over North Africa). Whilst we already have these aeroplanes represented, I think that it would be worth just checking over their FM along with the other Spitfire Vs.

The main reason for the increased boost being acceptable with the "M" engines was the reduction in charge temperature caused by the reduced supercharger impeller tip speed (just in case anybody is interested). Charge temperature was also the reason why the Merlin 61 could only manage +15 psi which was rather less than contemporary single stage engines. Hence the subsequent emphasis placed upon charge cooling.

I would also like to point out the difference between operational limits (such as the typical 5 minute combat rating limit see on many marks of Merlin) and the point at which the engine would fail.

Engine ratings are set at a level intended to give sensible safe engine lives.

For example, if the average flight is 1 hour, and you want 100 flights then you need the engine to have a safe life of 100 hours.

If the engine can only safely run at combat rating for say 500 minutes, then you'd allocate 5 minutes per flight.

But on flight #1 it's quite likely that you could considerably exceed the 5 minute limit without anything going wrong. The problem would be that if such behaviour were habitual then you'd run out of life well before flight #100, possibly resulting in engine failure when some unfortunate other person was flying well within the published limits.

For this reason, I think that it would be better if engine failures caused by high power abuse happened at random after the rated limits were exceeded, rather than deterministically based upon an "overheat timer" as is currently the case.

JtD
02-09-2010, 11:04 AM
That's a neat Merlin pdf you linked there.

Yes, the overly simple engine stress damage model could use some improvements, neg g, too.

Kettenhunde
02-09-2010, 11:19 AM
which mainly serves to improve fuel economy


Metering to the intake makes for uneven metering in the combustion chamber. That means cylinders run rich or lean unevenly and combustion is not efficient.

That robs power.

Direct fuel injection precisely meters fuel to the chamber so that it is more efficient and develops more power than injection at the intake.

It really is that simple.


The major advantages of a GDI engine are increased fuel efficiency and high power output.

http://en.wikipedia.org/wiki/G...ine_direct_injection (http://en.wikipedia.org/wiki/Gasoline_direct_injection)


The direct-injection system then takes this hardware up a notch. First, the evaporation of the tiny droplets of fuel injected directly into the cylinder (at between 450 and 1700 psi) cools the intake mixture, producing a denser charge, which means more power.

Furthermore, the cooler charge is less prone to detonation. Further detonation resistance comes from more rapid combustion, which occurs because although the overall charge mixture is stoichiometric, the charge is locally richer in the vicinity of the spark plug. This causes the mixture to light off more vigorously and progress more quickly. Faster combustion means less spark advance, which is inherently more efficient and further reduces detonation sensitivity.

The payoff is a lofty compression ratio—12.5 to 1. That's one to two points higher than that of typical engines, which often require premium fuel. Eiser promises that his engine will be happy on a diet of regular.

Higher compression extracts more energy from each droplet of fuel. Peak power for the 3123cc FSI V-6 is 255 horsepower at 6500 rpm; peak torque is 243 pound-feet at 3250 rpm. That represents 77.8 pound-feet for every liter of displacement. The comparable figure for BMW's 3.0-liter six is 71.8, 74.3 for the Infiniti G35 V-6, and 75.9 for the Porsche 911 flat-six.

http://www.caranddriver.com/fe...ally_make_it_-column (http://www.caranddriver.com/features/04q2/will_gasoline_direct_injection_finally_make_it_-column)

No you cannot fault RR choices. While not the ideal metering system, it is a very good system which is leaps and bounds ahead of a carburetor.

DI is very complicated and an engineering nightmare. That the Germans put DI aeroengines into full scale operational use is quite an engineering feat.

badatflyski
02-09-2010, 01:30 PM
Originally posted by thefruitbat:
i stand corrected.

makes no difference to what i was asking for though. as far as the game goes it will lead to not having neg g cutout, which is how all the spits are at the moment...

I'm asking for the neg g to be moddeled before the merlin 50, as before the su carb they didn't have throttle body injection, but with a few seconds grace to simulate miss shillings orifice...

happy?

actually, there is more than just this one difference between carb and injection in the game.

From the few points i did understand from the reading of the game's code, an injected engine keeps up the revs much better than a carb-engine, the last one not beeing able to develop the asked by the player power in several circumstancies as neg G, High AoA.

dus for those that always asked them why the 190 drop so much rev's when climbing and in some acrobatics, that's the reason.

Actualy, the Merlins till the 61 shouldall have a "pause" in their power curve when in Neg G's, the engine not having enough fuel to get in revs, and even cutting out after few secs in neg G's,not so prononced as with a float carb but still present.


About the boost level.
the spit 5 seems to have actually 2 of them.
At take-off and emergency 12boost limited at 3min but the other "emergency power" limited to 5min is 9boost at altitude!

So in this case, FC has to rewrite the spit5 class completly, with an exception rule for the boost limitation in 2 different situations!
That's not something so easy to do http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

also, the spit was a plane that has to be flown with 2 throttles, the boost throttle and the rev throttle, something that does not exist in the game, every player setting the pitch at max and keeping it there, only playing with the boost throttle, also something to look at...and not forgetting to delete the slider option for the flaps for the spit...just giving ideas FC http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif


PS: there was no SPIT Mk5B with the M50 engine (except the 3 i've noted earlier)
The most used engines were M45+45M+46

the m46 beeing a M45 with slightly better altitude perfs.(info tp be checked)

JtD
02-09-2010, 01:50 PM
I think the M46 was mainly a Merlin with worse low altitude performance than the M45. If you check into plane or engine performance, the advantages up high are so small that you can't see them in tests. The disadvantages at lower alt, however, are quite noticeable. So for the gain of 1 or 2% up high you lose 7 to 9 down low. Just check take off power at 12lb.

Insuber
02-09-2010, 02:54 PM
Viper, excellent link to that Merlin article! Thank you.

Insuber

yuuppers
02-09-2010, 04:59 PM
Originally posted by badatflyski:
also, the spit was a plane that has to be flown with 2 throttles, the boost throttle and the rev throttle, something that does not exist in the game, every player setting the pitch at max and keeping it there, only playing with the boost throttle, also something to look at...and not forgetting to delete the slider option for the flaps for the spit...just giving ideas FC http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

There is only one throttle lever. The other lever is for mixture.

na85
02-09-2010, 05:28 PM
Originally posted by yuuppers:

There is only one throttle lever. The other lever is for mixture.

No manual prop pitch?

JtD
02-10-2010, 09:11 AM
Yes, there's manual prop pitch on Spitfires MkV.

TheGrunch
02-10-2010, 09:29 AM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> In the Spitfire II Pilot's Notes the engine limitations were clearly stated to be exactly the same as those in the Spitfire Mk. V handbook, +12lbs (takeoff or 3 minutes) and +9lbs (5 minutes), yet pilots regularly exceeded +9lbs in combat if you read pilot accounts.
All instructions are specific and apply to that engine listed. You cannot apply them to any other circumstances. </div></BLOCKQUOTE>
Well, the engine limitations in the POH for the Spitfire Mark II do NOT mention that the +12lbs boost is allowed in combat or emergency situation either. Yet we know that it WAS used with frequency. Whether the engines are different or not, I can't believe that a pilot would decline to use an emergency boost that was definitely available to him and that he HAD already used with regularity in contravention to the POH for a previous mark of the aircraft. Up to the pilot, like I said. Death or *possible* engine failure, easy decision IMO.
It seems like the POHs for British aircraft were rarely up-to-date with currently-cleared engine limitations. The problem we have is that the POHs would have extra pages clipped to them as new information was added, but the reproductions offered by museums and from the National Archives obviously do not contain this information since they just represent full editions of the handbooks.

na85
02-10-2010, 10:14 AM
Originally posted by JtD:
Yes, there's manual prop pitch on Spitfires MkV.

So this is false?


There is only one throttle lever. The other lever is for mixture.

JtD
02-10-2010, 10:23 AM
Well, that depends on your definition of throttle lever, but the throttle quadrant in the Spitfire V had two levers, for mixture and throttle, and mounted onto the side of that box and also part of the throttle quadrant was a propeller speed controls, aka the propellor pitch control.

You can see that in game, too. Just change pitch and look what's moving.

na85
02-10-2010, 11:07 AM
Well, that depends on your definition of throttle lever, but the throttle quadrant in the Spitfire V had two levers, for mixture and throttle, and mounted onto the side of that box and also part of the throttle quadrant was a propeller speed controls, aka the propellor pitch control.

Ok.


You can see that in game, too. Just change pitch and look what's moving.

Yeah you're right that would have been easier

Kurfurst__
02-10-2010, 03:15 PM
Originally posted by TheGrunch:
Well, the engine limitations in the POH for the Spitfire Mark II do NOT mention that the +12lbs boost is allowed in combat or emergency situation either.

No, this is incorrect, they do mention +12 lbs boost, when it was cleared. Early ones do not mention it, and in fact say that +9 is approved as maximum for all other conditions expect for takeoff conditions. The later ones


Yet we know that it WAS used with frequency.

How? Pilot accounts? - if so, I would like to see a Pilot account from a Mark II Spitfire pilot say example from June 1940, saying he is using higher ratings than laid out in the June 1940 manual, which would be a bit odd considering there were no Spitfire Mark IIs in operation until August (and even then, only a few)... I guess you mix here up several anecdotes for different Marks of Spitfires..


Whether the engines are different or not, I can't believe that a pilot would decline to use an emergency boost that was definitely available to him and that he HAD already used with regularity in contravention to the POH for a previous mark of the aircraft. Up to the pilot, like I said. Death or *possible* engine failure, easy decision IMO.

It is true, but either you apply a level, objective playing field for all aircraft models or not. Theoretically it would be easy for the ground crew to adjust to throttle to any setting, including higher ones that were allowed officially - there is evidence that for example some P40 crews did that. It just opens a can of worms, ie. if you allow it for one aircraft, why dont you allow for another to fly at unofficial ratings..?


It seems like the POHs for British aircraft were rarely up-to-date with currently-cleared engine limitations. The problem we have is that the POHs would have extra pages clipped to them as new information was added, but the reproductions offered by museums and from the National Archives obviously do not contain this information since they just represent full editions of the handbooks.

Indeed, but they do represent the conditions in existence at the date they were published. Manuals were updated and re-issued when something changed. If nothing changed, nothing was changed in the manual. Its simple, and there's no need to develop complicated conspiracy theories around it.

For example, say someone says that Spitfire Is were using +12 lbs boost in 1940. We can check it against evidence - it is written in the manual of the aircraft, check. It is told by Pilots in their combat reports, check. It is listed as a rating for the Merlin III that powered the Spitfire I, check yet again.

Now, compare that to when someone says that Spitfire Vs were using +12 lbs boost in 1941. We can check it against evidence - it cannot be found in the manual of the aircraft, no pilots claim using it in their combat reports, and the same engine curve that list the a rating for the Merlin III that powered the Spitfire I at +12, shows the limitation of the Merlin XLV that powered the Mark V as +9... from that point onwards, the belief simply becomes a case irrationality.

Kurfurst__
02-10-2010, 03:18 PM
Originally posted by FatCat_99:
First of all I want to thank everybody who participated in this thread, it was very informative. Can we say now that we need all 3 of MkV max. boost levels represented?
That way 9lb would cover 1941, 12lb for early 1942 and 16lb for late 1942 and 1943.

FC

You are welcome, it has been an informative thread - and yes it appears to me a need a +9/1941 one (dont we have that one already? or was it a mix of a Mark V w. +9 speed, +16 climb?), a +12/1942early and a +16/1942late as far as the non-LF Mark Vs go.

TheGrunch
02-10-2010, 05:25 PM
Originally posted by Kurfurst__:
... from that point onwards, the belief simply becomes a case irrationality.
I think you're right. It's hard to know when things happened between full editions of the handbooks, I guess it's better to stick with them unless people find more detailed info.

VW-IceFire
02-10-2010, 05:30 PM
Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FatCat_99:
First of all I want to thank everybody who participated in this thread, it was very informative. Can we say now that we need all 3 of MkV max. boost levels represented?
That way 9lb would cover 1941, 12lb for early 1942 and 16lb for late 1942 and 1943.

FC


You are welcome, it has been an informative thread - and yes it appears to me a need a +9/1941 one (dont we have that one already? or was it a mix of a Mark V w. +9 speed, +16 climb?), a +12/1942early and a +16/1942late as far as the non-LF Mark Vs go. </div></BLOCKQUOTE>

That sounds really great to me! It would fill in lots of gaps and be great for online and offline scenario builders like myself.

I say again that sometimes the Mark IX gets used in a scenario because it "was there" although it was extremely rare at the time and the early performing/messed up performing of the Mark Vb/Vc we have now simply don't cut it versus the opposition. We can then keep the IX in the fights it really dominated (numbers wise) in and mix up the online scenarios a bit.

*fingers crossed*

JG53Frankyboy
02-10-2010, 05:36 PM
and please dont forgett the LF ones.
I love the idea of such lowlevel hotrods http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif
IIRC they came in Service 1943.
i dont know if one for 43 and one for 44 would be "needed" .

hop2002
02-10-2010, 05:54 PM
It is true, but either you apply a level, objective playing field for all aircraft models or not. Theoretically it would be easy for the ground crew to adjust to throttle to any setting, including higher ones that were allowed officially - there is evidence that for example some P40 crews did that. It just opens a can of worms, ie. if you allow it for one aircraft, why dont you allow for another to fly at unofficial ratings..?

I agree about the unofficial ratings. But if a pilot manual says "pull this lever for emergency boost", and the RAF/manufacturer has fitted the control that provides the extra boost, then that's not an unofficial rating.


For example, say someone says that Spitfire Is were using +12 lbs boost in 1940. We can check it against evidence - it is written in the manual of the aircraft, check.

Is it? Do you have a Spitfire I manual from the summer of 1940? I'd really like to see it, if you have one.


Now, compare that to when someone says that Spitfire Vs were using +12 lbs boost in 1941. We can check it against evidence - it cannot be found in the manual of the aircraft

Do you have a Spitfire V manual from 1941? Again, I'd really like to see it if you do.


no pilots claim using it in their combat reports

How many combat reports do we have?


and the same engine curve that list the a rating for the Merlin III that powered the Spitfire I at +12, shows the limitation of the Merlin XLV that powered the Mark V as +9.

Date?

What we have for the Spitfire I is instructions dating from the switch over to 100 octane fuel, and combat reports from the BoB.

Neither of those special circumstances apply to the Spitfire V, Merlins were already using 12 lbs boost on 100 octane fuel, and of course the BoB was over. It's hardly surprising there is less evidence for the Spitfire V.

We do have the MAP saying the Merlin 45 was introduced with 12 lbs boost, in a letter dated 3 January 1942, so unless there's evidence to the contrary, the assumption must be that 12 lbs was in use for the Spitfire V from the start.

M_Gunz
02-10-2010, 08:18 PM
For takeoff and emergencies only, right?

I mean, the cut-out control was factory made and explained... funny way to make sure it's not used.
Overhaul is a lot cheaper than replacing an engine let alone a whole airplane and pilot!

FatCat_99
02-11-2010, 06:47 AM
Originally posted by thefruitbat:
I'm asking for the neg g to be moddeled before the merlin 50, as before the su carb they didn't have throttle body injection, but with a few seconds grace to simulate miss shillings orifice...

We will try to do something about it.


Originally posted by badatflyski:
PS: there was no SPIT Mk5B with the M50 engine (except the 3 i've noted earlier)
The most used engines were M45+45M+46

Rgr, although it is not that important how engines are called internally as long as performance is what we want it to be.


Originally posted by JG53Frankyboy:
and please dont forgett the LF ones.
We are thinking about these too, and that is not all. Idea behind rework of Spits is to make best possible mid war WF scenario. So we will have to add SpitMkIX with Merlin61 and on the other side rework Bf109F4,G2,G6 and add FW190A4 1,42ATA . With these plane we will have great WF fighter matchup. Balanced and interesting and still historical.

FC

thefruitbat
02-11-2010, 07:03 AM
Fatcat, this is great news, you are a legend http://forums.ubi.com/images/smilies/11.gif http://forums.ubi.com/images/smilies/11.gif http://forums.ubi.com/images/smilies/11.gif

Kwiatos
02-11-2010, 12:24 PM
Originally posted by FatCat_99:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by thefruitbat:
I'm asking for the neg g to be moddeled before the merlin 50, as before the su carb they didn't have throttle body injection, but with a few seconds grace to simulate miss shillings orifice...

We will try to do something about it.


Originally posted by badatflyski:
PS: there was no SPIT Mk5B with the M50 engine (except the 3 i've noted earlier)
The most used engines were M45+45M+46

Rgr, although it is not that important how engines are called internally as long as performance is what we want it to be.


Originally posted by JG53Frankyboy:
and please dont forgett the LF ones.
We are thinking about these too, and that is not all. Idea behind rework of Spits is to make best possible mid war WF scenario. So we will have to add SpitMkIX with Merlin61 and on the other side rework Bf109F4,G2,G6 and add FW190A4 1,42ATA . With these plane we will have great WF fighter matchup. Balanced and interesting and still historical.

FC </div></BLOCKQUOTE>

So it looks that i got competition now ;p

badatflyski
02-11-2010, 01:32 PM
Originally posted by FatCat_99:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by badatflyski:
PS: there was no SPIT Mk5B with the M50 engine (except the 3 i've noted earlier)
The most used engines were M45+45M+46

Rgr, although it is not that important how engines are called internally as long as performance is what we want it to be.

</div></BLOCKQUOTE>

Indeed, you can call it whatever you want,even plasmaengine if you want http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif (refering to the name oleg gave the shkvas 20mm http://forums.ubi.com/images/smilies/88.gif )

the perfs are much more important than the name, but not only them, also all the rest, i mean other DM possibilities, just like the one you've made for the 109 as a test a year ago http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif or the "K" factor and the drag that are just "slightly" exagerated in the spits series.

Have fun FC! http://forums.ubi.com/images/smilies/inlove.gif

JtD
02-11-2010, 11:31 PM
How exactly would "not that good" neg g behaviour look like?

Where's the problem in the Spitfires installation? 0g? To many neg g? What's the effect - less power, no power?

Kettenhunde
02-12-2010, 06:33 AM
Where's the problem in the Spitfires installation? 0g? To many neg g? What's the effect - less power, no power?


The float in the carburetor closes in -Gz shutting off the fuel flow to the engine. There is a second or two of remaining fuel in the float bowl that gets used up and then the motor stops running completely.

Think of it like a WWII version of the "blip throttle". The engine cuts out. The propeller disc begins braking the aircraft. That same action drives the propeller to continue turning and driving the magnetos. When fuel flow is restored, the engine restarts and continues running as long as it has fuel.

Miss Shillings orifice converts a float carburetor to a diaphragm which is more tolerant of Gz.

yuuppers
02-12-2010, 07:39 AM
The -G cut-out was a 2 stage event. At the onset of -G fuel was forced to the top of the float chamber, which exposed the main jets to air. This caused a momentary, lean cut-out. If a -G condition continued, the floats reacted to the reverse of normal conditions and floated the wrong way, that is, they floated to the bottom of the float chamber. The needle valve opened, allowing fuel pressure from the engine driven pump to flood the carburettor, An excessively rich mixture was then admitted into the supercharger causing a more serious rich cut-out.

JtD
02-12-2010, 07:53 AM
Thanks for that, but wouldn't that be for the simple carburettor?

I was looking for info on the first neg-g carburettors, which were supposed to solve the problem, but only managed to lessen it.

Kettenhunde
02-12-2010, 09:07 AM
Miss Shillings orifice converts a float carburetor to a diaphragm which is more tolerant of Gz.


That is bad information. It is a restricter plate on the fuel side.

Same thing is used in mixture control circuits today too.

The plate assumes a fixed manifold pressure so irregardless of throttle setting, it will move the engine to the orifice manifold pressure under -Gz.

yuuppers
02-12-2010, 09:32 AM
The Shilling Orifice was sized to allow only the amount of fuel needed to satisfy maximum engine output.

Kettenhunde
02-12-2010, 11:00 AM
The Shilling Orifice was sized to allow only the amount of fuel needed to satisfy maximum engine output.

Instead of cutting out from an overly rich mixture, the engine opened up to the appropriate boost for the plate installed.

Throttle does not control the fuel flow in a float carburetor, Milo. It controls the airflow with spring loaded butterfly valves and as the airflow increases, fuel different power band fuel jets and venturi's are activated.

That is not longer an option and the fuel flow is constant set to IIRC, +9lbs or +12lbs. When negative G's are applied and the float tries to reverse, instead of dying, the engine opens up to whichever manifold pressure corresponds to the installed plate irregardless of the pilots throttle setting.

Later, the Merlins got pressure carburetors which are much better. Miss Schillings orifice is still head and shoulders about having the engine cut out under -Gz.

yuuppers
02-12-2010, 01:01 PM
What are you babbling on about Eugene? Where do you get 'throttle' and 'fuel flow' from? http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

You remember wrong. Two restricters were developed, one for 12lb boost and another for 16lb boost.

Since you are confused, the Shilling Orifice, was at the main fuel inlet to the carb. It had nothing to do with the jets feeding fuel to the venturi of the carb.

JtD
02-12-2010, 01:34 PM
Originally posted by yuuppers:
The Shilling Orifice was sized to allow only the amount of fuel needed to satisfy maximum engine output.

I've visited Wikipedia in the meantime and got me a little background on this. Nice reads. What they say is that the Shilling Orifice (SO) allowed short time neg g (as used in maneuvers where you just push the nose down), while the engine would still quit in extended neg g situations (like flying inverted).
This somehow opposes the working principle as I understand it, since the SO would keep the engine from drowning in fuel, which should be the reason for the engine problems in extended neg g maneuvers, while it would do nothing to help it through the initial lean phase. So I'd expect a short stutter when I push it over, and then no more problems from that side.

What did I miss?

Kettenhunde
02-12-2010, 01:57 PM
and then no more problems from that side.


That is about right. The engine will kick over into either +9 or +12lbs depending on the orifice installed rather than cutting out.

The SU single point injection eliminated this issue in 1944.

Xiolablu3
02-13-2010, 06:01 AM
As I remember it, the orifice was a spongy foam disc, which simply blocked the fuel from flooding the carb in brief neg G manouvres.

If extended Neg G manouvres were carried out (flying upside down for long periods) the fuel would soak through the disc and flood the carb.

thats how I always understood it worked.

EDIT : Wiki says it was a metal disc, so I am probably wrong here.

Kettenhunde
02-13-2010, 06:37 AM
the orifice was a spongy foam disc,


It is a metal disc not a sponge.