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AKA_TAGERT
04-01-2007, 05:48 PM
What with all the att the P-47D 1944 is getting I thought it only fair to start looking at some of the other Allied planes again..

Here is the first of more to come.

http://www.airwarfare.com (http://www.airwarfare.com/phpBB2/viewtopic.php?t=1970)

Enjoy!

PS I want to thank Viper2005 for sparking my interest in all this again! I had kind of gave up on testing stuff.. but his 'methods' motivated me to start doing it again.

AKA_TAGERT
04-01-2007, 05:48 PM
What with all the att the P-47D 1944 is getting I thought it only fair to start looking at some of the other Allied planes again..

Here is the first of more to come.

http://www.airwarfare.com (http://www.airwarfare.com/phpBB2/viewtopic.php?t=1970)

Enjoy!

PS I want to thank Viper2005 for sparking my interest in all this again! I had kind of gave up on testing stuff.. but his 'methods' motivated me to start doing it again.

VW-IceFire
04-01-2007, 08:26 PM
Interesting. Pretty consistently similar to the RW data...just a little "too good". But I think running the test at 100% might be interesting too!

Thanks for the test. Its very interesting to see the graphs and charts!

Viper2005_
04-01-2007, 09:16 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I'm not 100% sure, but looking at the MP graph it appears that I was pushing the in game Tempest harder than they did in the real world testing. In the link to the real world data it does have an asterisk at 0ft and 13500ft where the asterisk denotes FULL THROTTLE HEIGHTS. Which leads me to belive they used less than FULL THROTTLE at all other altitudes. </div></BLOCKQUOTE>

Nope.

Like most British aircraft of the period, the Tempest had an automatic boost control unit.

The cockpit throttle lever is not connected directly to the throttle valve on the engine. Instead it is connected to the boost control unit, which in turn controls throttle valve position.

The ABC tries to maintain constant intake manifold pressure by moving the throttle valve.

FTH is the altitude at which the throttle must be fully opened to deliver the commanded boost pressure. Above FTH the boost (manifold pressure in American terminology) starts to fall off.

Without the ABC the pilot would have to continually adjust the throttle to maintain constant boost in response to changes in external air pressure and ram pressure (ie changes in altitude, airspeed & weather).

Of course, below FTH there is always scope to open the throttle and obtain more power provided that the engine and fuel can handle it; this was done to great effect with the +25 Mustang III & Spitfire, and indeed with many other types such as the P-47.

Of course from FTH upwards the throttle is already open and so you'll see no benefit from higher performance fuel.

Now, in the game all piston engines behave as though they are fitted with ABC. 100% throttle opening actually gives you the maximum rated boost pressure for whatever engine you're dealing with. 110% throttle opening gives you WEP, except in the case of those aircraft fitted with boost systems in which case you sometimes have to engage the system in order to get combat power. IRL many aircraft were not fitted with ABC, and so the pilot had to manually maintain boost pressure within limits which could cause problems if rapid changes in altitude and airspeed were required, especially in the absence of constant speed props.

***

In the case of the Tempest in game, all you need to do is open up to 110%, hit the WEP button and change supercharger gears at the correct altitude (8700 feet) and you should replicate the R/L test schedule.

However, it would also be interesting to repeat the test changing supercharger gears at +4 psi boost in order to see how accurate the aircraft's performance is when flown according the gauges. (probably not very given that it's rather difficult to set the engine to max continuous...)

You should check your tables; you've got ROC in feet labelled as m/s for example.

Also since we know that the s/c gear was changed at +4 psi your boost pressure best fit line is incorrect; when +4 is reached it should show a neat discontinuity up to +9 psi as seen in the game data. This may be seen here:

http://www.spitfireperformance.com/tempest/jn731climb.jpg

AKA_TAGERT
04-01-2007, 10:04 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by VW-IceFire:
Interesting. Pretty consistently similar to the RW data...just a little "too good". But I think running the test at 100% might be interesting too!

Thanks for the test. Its very interesting to see the graphs and charts! </div></BLOCKQUOTE>My Pleasure!

AKA_TAGERT
04-02-2007, 07:15 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I'm not 100% sure, but looking at the MP graph it appears that I was pushing the in game Tempest harder than they did in the real world testing. In the link to the real world data it does have an asterisk at 0ft and 13500ft where the asterisk denotes FULL THROTTLE HEIGHTS. Which leads me to belive they used less than FULL THROTTLE at all other altitudes. </div></BLOCKQUOTE>

Nope.

Like most British aircraft of the period, the Tempest had an automatic boost control unit.

The cockpit throttle lever is not connected directly to the throttle valve on the engine. Instead it is connected to the boost control unit, which in turn controls throttle valve position.

The ABC tries to maintain constant intake manifold pressure by moving the throttle valve.

FTH is the altitude at which the throttle must be fully opened to deliver the commanded boost pressure. Above FTH the boost (manifold pressure in American terminology) starts to fall off.

Without the ABC the pilot would have to continually adjust the throttle to maintain constant boost in response to changes in external air pressure and ram pressure (ie changes in altitude, airspeed & weather).

Of course, below FTH there is always scope to open the throttle and obtain more power provided that the engine and fuel can handle it; this was done to great effect with the +25 Mustang III & Spitfire, and indeed with many other types such as the P-47.

Of course from FTH upwards the throttle is already open and so you'll see no benefit from higher performance fuel.

Now, in the game all piston engines behave as though they are fitted with ABC. 100% throttle opening actually gives you the maximum rated boost pressure for whatever engine you're dealing with. 110% throttle opening gives you WEP, except in the case of those aircraft fitted with boost systems in which case you sometimes have to engage the system in order to get combat power. IRL many aircraft were not fitted with ABC, and so the pilot had to manually maintain boost pressure within limits which could cause problems if rapid changes in altitude and airspeed were required, especially in the absence of constant speed props. </div></BLOCKQUOTE>
That's nice.

But..

Your missing the point going off on that MP tangent in that the real world data stated FULL THROTTLE (Their words not mine) at only two altitudes.

There are other indicators, MP is just one of them. Which should not be taken too seriously in the first place in that as I noted in this and several other threads the MP gauges are just for show. So they may be off because they are simply models and do not factor into the performance what so ever.

Thus, back to the point, like I said, I think I may have been pushing it harder than the real test.. In that I was using FULL THROTTLE i.e. 110% at all altitudes, except or the times that I was allowing the engine to cool off.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
In the case of the Tempest in game, all you need to do is open up to 110%, hit the WEP button and change supercharger gears at the correct altitude (8700 feet) and you should replicate the R/L test schedule.

However, it would also be interesting to repeat the test changing supercharger gears at +4 psi boost in order to see how accurate the aircraft's performance is when flown according the gauges. (probably not very given that it's rather difficult to set the engine to max continuous...) </div></BLOCKQUOTE>
Real World Data showed them switching it at 10ft. That and Oleg has said the guages are only for show.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
You should check your tables; you've got ROC in feet labelled as m/s for example. </div></BLOCKQUOTE>
Ah missed that one, thanks Ill fix it.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Also since we know that the s/c gear was changed at +4 psi your boost pressure best fit line is incorrect; when +4 is reached it should show a neat discontinuity up to +9 psi as seen in the game data. </div></BLOCKQUOTE>
Well that would be a pretty neat trick in that I never did a 'best fit' of the boost pressure..

Thus 'it' can not be 'incorrect' in that I never did one!

The real world boost plots are simple point-to-point lines as noted in the graph.

The only 'best fitting' I did was for the in game ROC plots.

Viper2005_
04-02-2007, 08:04 AM
Yet again your poor level of reading comprehension has damaged your understanding of several rather simple concepts. Please take the time to read more carefully.

The throttle lever in the cockpit is not connected directly to the throttle butterfly valves.

It is connected to the Automatic Boost Control unit (ABC). This greatly simplifies engine handling because it means that any given throttle angle translates to a constant boost pressure at any altitude less than or equal to the Full Throttle Height (FTH).

In the context of your Tempest test for example, the pilot would open the throttle in the cockpit all the way through the gate (directly equivalent to 110% plus WEP in the game). This would command the ABC to deliver the maximum permitted combat boost of +9 psi.

The ABC would then compare the intake manifold pressure with the commanded boost pressure. If the intake manifold pressure was greater than the commanded boost pressure it would close the throttle valves. If the intake manifold pressure was less than the commanded boost pressure it would shut the throttle valves.

This means that below FTH, no matter how far forward the pilot pushed the throttle lever, the throttle butterfly valves would not be fully open.

The FTH for any given boost pressure at any given rpm and airspeed is the height at which the ABC would be forced to fully open the throttle butterfly valves to attain that boost pressure at that rpm and airspeed.

Therefore, in the context of your Tempest test, the correct procedure is simply to open up to 110% throttle with the WEP button pressed and then pitch to maintain the desired IAS, remembering to change supercharger gears at either the correct altitude (8700 feet) or the correct boost pressure (+4 psi).

Now, as for best fit lines, I refer to this graph:

http://www.geocities.com/grantsenn/NACA_TESTING/ANALYSIS/TEST_TYPE/ROC/408/TEMPEST/ME_01/MP.JPG

The point I am making is that drawing straight lines between the real world data points in this manner is misleading because in fact the RW data would obviously exhibit a discontinuity at 8700 feet when the supercharger gear change takes place.

The report is quite explicit on the point of supercharger gear changes, but just to make sure, I've highlighted for you:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Climb performance at combat rating
Take-off weight - 11,480 lb.
Radiator Flap open
<span class="ev_code_red">Supercharger gear changed when boost in
M.S. gear fell to +4 lb/sq.in.</span> </div></BLOCKQUOTE>

Now read across to the 8700 feet line and you will see that the boost pressure is +4 psi. Therefore immediately that this data point was recorded the supercharger gear was changed.

You will note that data recorded fits into a nice pattern. Data was recorded at altitudes of:

0* (FTH for +9 psi in MS gear)
4000
8700 (+4 psi in MS gear)
10000
13500* (FTH for +9 psi in FS gear)
15000
18000
20000
22000
24000
26000
28000
30000
32000
34000

The only data points which aren't multiples of 1000 feet are the FTHs and the supercharger gear change height of 8700 feet. Even if you don't bother to read the information provided it should be quite obvious that there was something special about 8700 feet in this test from the fact that it is not a multiple of 1000 feet. Since the FTHs are marked, again it doesn't take a rocket scientist to work out that this is the s/c gear change altitude.

This pattern is replicated in the test at normal rating (+7 psi)

Again, if you read the information above the table:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Climb performance at normal rating
Take-off weight - 11,480 ib.
Radiator Flap open
<span class="ev_code_red">Supercarger gear changed when boost in
M.S. gear fell to +2.9 lb/sq.in.</span> </div></BLOCKQUOTE>

Now read across the 10700 ft line and you will see a boost pressure of +2.9 psi. Therefore the supercharger gear change took place at 10700 feet in this test. Again, if you don't believe this and/or haven't bothered to read the information provided you should still be asking yourself what was so special about 10700 feet that they chose to make it a data point.

AKA_TAGERT
04-02-2007, 08:30 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Yet again your poor level of reading comprehension has damaged your understanding of several rather simple concepts. Please take the time to read more carefully. </div></BLOCKQUOTE>
Hardly..

It is you that have the reading problem.. In that you were in such a rush to tell us how the MP works in the Tempest that you miss the whole point of my statement. Funny to in that I have told you several times in the past that the in-game MP gauges are just for show thus not detailed models that would be expected to mach real world data. Yet that is where you focus and thus tangent topic went. The only part I am not sure about is if you did it in a sort of ˜look at me I know something' manor or in an attempt to take the focus off the possibility that I pushed the in-game Tempest harder than the real test. Either way it is a bad thing IMHO and speaks volumes about you and your purposes here.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
The throttle lever in the cockpit is not connected directly to the throttle butterfly valves.

It is connected to the Automatic Boost Control unit (ABC). This greatly simplifies engine handling because it means that any given throttle angle translates to a constant boost pressure at any altitude less than or equal to the Full Throttle Height (FTH). </div></BLOCKQUOTE>
There you go again!

Ok Ill play your little game.

Now.. Quote me where I ever said the throttle was or was not directly connect! In that you seem to be under the impression that I did say that! But allow me to save you the time looking for where I said that.

NO WHERE!

All I did was point out the FACT that the real world data notes that FULL THROTTLE (their words not mine) at only two altitudes.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
In the context of your Tempest test for example, the pilot would open the throttle in the cockpit all the way through the gate (directly equivalent to 110% plus WEP in the game). This would command the ABC to deliver the maximum permitted combat boost of +9 psi.

The ABC would then compare the intake manifold pressure with the commanded boost pressure. If the intake manifold pressure was greater than the commanded boost pressure it would close the throttle valves. If the intake manifold pressure was less than the commanded boost pressure it would shut the throttle valves.

This means that below FTH, no matter how far forward the pilot pushed the throttle lever, the throttle butterfly valves would not be fully open.

The FTH for any given boost pressure at any given rpm and airspeed is the height at which the ABC would be forced to fully open the throttle butterfly valves to attain that boost pressure at that rpm and airspeed.

Therefore, in the context of your Tempest test, the correct procedure is simply to open up to 110% throttle with the WEP button pressed and then pitch to maintain the desired IAS, remembering to change supercharger gears at either the correct altitude (8700 feet) or the correct boost pressure (+4 psi). </div></BLOCKQUOTE>
Which is exactly what I did!

But..

The point your not addressing here is the real world data says FULL THROTTLE at only two altitudes.

Therefore it implies that FULL THROTTLE was not used all the time. Or it may be the points where the butterfly valve was fully open?

But if that was the case one would expect them to say that instead of FULL THROTTLE.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Now, as for best fit lines, I refer to this graph:
http://www.geocities.com/grantsenn/NACA_TESTING/ANALYSI...TEMPEST/ME_01/MP.JPG (http://www.geocities.com/grantsenn/NACA_TESTING/ANALYSIS/TEST_TYPE/ROC/408/TEMPEST/ME_01/MP.JPG) </div></BLOCKQUOTE>
So what part of the graph NOT saying best fit are you having trouble with?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
The point I am making is that drawing straight lines between the real world data points in this manner is misleading because in fact the RW data would obviously exhibit a discontinuity at 8700 feet when the supercharger gear change takes place. </div></BLOCKQUOTE>
And the point I am making is the graph does not say BEST FIT!

It clearly says STRAIGHT LINE FIT!

If the difference between a STRAIGHT LINE and BEST fit is not clear to the person reading the graph, than said person should not be reading graphs in the first place! (HINT HINT)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
The report is quite explicit on the point of supercharger gear changes, but just to make sure, I've highlighted for you:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Climb performance at combat rating
Take-off weight - 11,480 lb.
Radiator Flap open
<span class="ev_code_red">Supercharger gear changed when boost in
M.S. gear fell to +4 lb/sq.in.</span> </div></BLOCKQUOTE>

Now read across to the 8700 feet line and you will see that the boost pressure is +4 psi. Therefore immediately that this data point was recorded the supercharger gear was changed.

You will note that data recorded fits into a nice pattern. Data was recorded at altitudes of:

0* (FTH for +9 psi in MS gear)
4000
8700 (+4 psi in MS gear)
10000
13500* (FTH for +9 psi in FS gear)
15000
18000
20000
22000
24000
26000
28000
30000
32000
34000]

The only data points which aren't multiples of 1000 feet are the FTHs and the supercharger gear change height of 8700 feet. Even if you don't bother to read the information provided it should be quite obvious that there was something special about 8700 feet in this test from the fact that it is not a multiple of 1000 feet. Since the FTHs are marked, again it doesn't take a rocket scientist to work out that this is the s/c gear change altitude.

This pattern is replicated in the test at normal rating (+7 psi)

Again, if you read the information above the table:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Climb performance at normal rating
Take-off weight - 11,480 ib.
Radiator Flap open
<span class="ev_code_red">Supercarger gear changed when boost in
M.S. gear fell to +2.9 lb/sq.in.</span> </div></BLOCKQUOTE>

Now read across the 10700 ft line and you will see a boost pressure of +2.9 psi. Therefore the supercharger gear change took place at 10700 feet in this test. Again, if you don't believe this and/or haven't bothered to read the information provided you should still be asking yourself what was so special about 10700 feet that they chose to make it a data point. </div></BLOCKQUOTE>
So what part of Oleg saying the MP gauges are just for show do you not understand?

I do understand, which is why I used the altitude listed in the REAL WORLD DATA as the point to switch the gear.

SAVVY?

JtD
04-02-2007, 08:39 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Which is exactly what I did! But the point your not addressing here is the real world data says FULL THROTTLE at only two altitudes. </div></BLOCKQUOTE>

http://forums.ubi.com/images/smilies/34.gif

Tagert, you so suck.

http://forums.ubi.com/images/smilies/34.gif

Not knowing what FTH means is one thing, but attacking folks who give you an explanation you should be grateful for - http://forums.ubi.com/images/smilies/34.gif.

AKA_TAGERT
04-02-2007, 08:42 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
http://forums.ubi.com/images/smilies/34.gif

Tagert, you so suck.

http://forums.ubi.com/images/smilies/34.gif </div></BLOCKQUOTE>
It only appears that way when standing next to you..

In that you blow! http://forums.ubi.com/images/smilies/mockface.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
Not knowing what FTH means is one thing, but attacking folks who give you an explanation you should be grateful for - http://forums.ubi.com/images/smilies/34.gif. </div></BLOCKQUOTE>
Full Throttle Height I presume?

I understand the auto pressure system that Viper described and how it would/could maintain the pressure independent of the throttle setting.

That is not the issue!

The aerospace jargon may be the issue? In that I'm not hip to all the aerospace jargon. So if FTH implies that the butterfly valve is fully open at that point.

Than my bad!

But I would like to see some reference to support that before I accept it!

The point both of your are missing is the in-game MP gauges are just for show and do not factor into the actual performance of the engine and thus the plane. Oleg only goes by two settings.. 100% and 110% throttle settings.

I've said it before and Ill say it again.. I'm not 109 or Tempest or any plane expert!

I am just the messenger!

I take the data at face value and post the results.. If you guys want to split hairs, by all means do so!

Viper2005_
04-02-2007, 12:20 PM
Ah, at last an admission that you don't know very much about aeroplanes. Progress at last!

The terminology in the Tempest report is pretty standard. Compare it with Spitfire reports, eg:

http://www.spitfireperformance.com/bs543.html

Or indeed with Mosquito reports, eg:

http://www.wwiiaircraftperformance.org/mosquito/mosquito.html

I have explained the definition of Full Throttle Height to you twice now. If you don't believe me then there is no shortage of evidence in the literature.

A quick search of the internet reveals the following rather nice explanation:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Cockpit engine controls

Pilot's engine power controls in the aircraft were quite simple. Mixture control was entirely automatic, although some early Firefly marks originally had manual control but were later modified to automatic. Unfortunately the modification did not require removal of the disconnected lever in the quadrant so I fancy a few aircraft were snagged after flight by puzzled pilots. The 2-position supercharger gear change control was usually switched to 'automatic' where an altitude switch effected the change between low and high gear when appropriate. The pilot could set the control at 'MS' [medium speed] in which case low gear was maintained at all altitudes. There was also a means provided for testing high gear operation during engine ground run-up.

The position of the rpm control lever adjusted the operating mechanism of the constant speed unit mounted on the engine. The CSU governed the engine rpm between about 1400 and 2700 in the Centaurus and 1800 and 3000 in the Griffon. The CSU functions by constantly adjusting the blade pitch to variations in power and in load imposed by flight functions. In Griffon engined aircraft the control lever could be pulled back through a gate which allowed rpm below 1800, but I think this might have been outside the governing range of the CSU. The Centaurus allowed an additional facility – pulling the lever back through the gate put rpm control into automatic mode and rpm are then controlled by the position of the interconnected throttle lever. When flying the Sea Fury the rpm lever was set to maximum rpm for take-off, pulled back to auto when airborne and usually left there until rejoining the circuit.

So, for some of these high performance aircraft, mixture, boost gear and rpm control were all automatic and the only engine control the pilot varied in flight was the throttle lever – just like most ultralights.

The throttle lever was connected to the automatic boost control which, in turn, controlled the opening of the throttle butterflies. Manifold pressure was boosted by the supercharger up to 18 lbs/sq.in above atmospheric pressure in the Griffon and 9 lbs in the Centaurus. [American practice is to measure boost as absolute pressure, expressed as inches of mercury, thus manifold pressure 30 in/hg in American engines equals zero boost in British]. The pilot sets the climbing power needed, for example, in the Seafire, maximum rate of climb 150 knots IAS, power +9 lbs and 2600 rpm , and the automatic boost control progressively opens the butterflies in the climb until the full throttle height, for that boost and rpm setting, is reached and boost begins to fall. Shortly after, the altitude switch should change the supercharger to high gear [which comes in with quite a 'clunk'], boost increases, throttle opening is consequently reduced and, as the climb continues, progressively re-opened until a second full throttle height is reached, then boost again falls. While this is going on the pilot sits back but needs to reduce IAS by about three knots per 1000 feet once past 25 000, thus maintaining a near constant TAS until at about 40 000 – 42 000 feet the engine starts to run out of grunt and the aircraft is approaching stall at 160 knots TAS. Airspeed also affects full throttle height, the ram effect of high airspeed helps the supercharger considerably, adding maybe 3000 feet at maximum airspeed.
</div></BLOCKQUOTE>
http://www.auf.asn.au/magazine/seafires1.html

TheycallhimJosh
04-02-2007, 01:07 PM
Yes,Taggot doesnt seem to know much at all except how to post insulting remarks and attempt to show some sort of "dominance".

AKA_TAGERT
04-02-2007, 01:25 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TheycallhimJosh:
Yes,Taggot doesnt seem to know much at all except how to post insulting remarks and attempt to show some sort of "dominance". </div></BLOCKQUOTE>Poooor Nancy

AKA_TAGERT
04-02-2007, 01:31 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Ah, at last an admission that you don't know very much about aeroplanes. Progress at last! </div></BLOCKQUOTE>
LOL!

Never said I was an expert!

Would love to see you quote me where I did!

But.. you wont!

Why?

Because I never did!

I don't know why I bother calling you out on this.. In that each time I do you just ignore it thinking that nobody noticed it! But I will have you know.. Over in HL on coms we get quite a good laugh at your expence at the way I keep pointing that out!

The last best laugh we had was you having the odasity to say my plot is 'missleading'

HA!

That comming from you was a real hoot! What with your weak attempt to paint the P-47D as some sort of over modeled uber allied plane!

So please don't stop! Your making me look good!

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
The terminology in the Tempest report is pretty standard. Compare it with Spitfire reports, eg:

http://www.spitfireperformance.com/bs543.html

Or indeed with Mosquito reports, eg:

http://www.wwiiaircraftperformance.org/mosquito/mosquito.html </div></BLOCKQUOTE>
Just to be crystal, I never said it was not standard! All I said is I am not hip to all the aerospace jargon. Two very different things

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
I have explained the definition of Full Throttle Height to you twice now. </div></BLOCKQUOTE>
Negative.. you explained how the 'system' maitained the pressure and how the throttle was not directly connected. Two things I never had any problem with let alone understanding. The only problem I have/had is with the jargon that FTH means the system is at it's max at that altitude.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
If you don't believe me then there is no shortage of evidence in the literature. </div></BLOCKQUOTE>
In light of your P47 fact spinning I not only require it but would demand a soruce other than you to belive the definition of FTH

TheycallhimJosh
04-02-2007, 01:35 PM
There he goes again.Afraid that the Moderators may review his unprovoked insults and arrogant posts,he reverts to his vaguely arrogant and insulting"poor nancy" expression,desperately hoping that the only place where he feels "superior" to others wont be affected by his behaviour.It's pathetic how you like to use the word "we" when describing your feelings as you try to attempt to defuse your insults,hiding behind others hoping for support.Moderators,Ban him Now.

AKA_TAGERT
04-02-2007, 01:37 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TheycallhimJosh:
There he goes again.Afraid that the Moderators may review his unprovoked insults and arrogant posts,he reverts to his vaguely arrogant and insulting"poor nancy" expression,desperately hoping that the only place where he feels "superior" to others wont be affected by his behaviour.Moderators,Ban him Now. </div></BLOCKQUOTE>Pooooor Nancy

Or should I call you my new groupie?

TheycallhimJosh
04-02-2007, 01:41 PM
Moderators,Review his posts and Ban him.His behaviour is abusive,arrogant,insulting and domineering and can easily be reviewed by searching.It is flagrantly in violation of the rules set by UBI and it would be a matter of extreme negligence if he were not Banned immediately.

AKA_TAGERT
04-02-2007, 01:42 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TheycallhimJosh:
Moderators,Review his posts and Ban him. </div></BLOCKQUOTE>
Pooooor Groupie

TheycallhimJosh
04-02-2007, 01:47 PM
Moderators,Ban him.

Viper2005_
04-02-2007, 01:47 PM
And I quote:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I've said it before and Ill say it again.. I'm not 109 or Tempest or any plane expert! </div></BLOCKQUOTE>

BTW, in future you might find this rather useful:

http://dictionary.cambridge.org/

AKA_TAGERT
04-02-2007, 02:01 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
And I quote:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I've said it before and Ill say it again.. I'm not 109 or Tempest or any plane expert! </div></BLOCKQUOTE> </div></BLOCKQUOTE>
LOL!

You got that 180 out son!

I said quote me where I said I WAS an expert! Quoting me where I said I WAS NOT an expert is very different!

But..

In light of your spin tatics employed in the P47 thread and others I am not suprised that you would 'think' they are one in the same.. Or at least try and sell them as such!

Nice try!

Gold Troll Star for effort!

But no sale!

AKA_TAGERT
04-02-2007, 02:03 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TheycallhimJosh:
Moderators,Ban him. </div></BLOCKQUOTE>What with you being new and all..

At least your current handle is new.. Only a week old!

Here is a little clue for you..

You stop following me around in every thread and you will solve the problem yourself!

Post something to me or about me in a thread I am in and you can expect a reply..

It is that simple Nancy.

PS what was your handle before last week? And did you have to make a new handle because you got banned.. Or were you just boored?

Viper2005_
04-02-2007, 02:30 PM
Tagert, your post made no grammatical sense.

I said:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Ah, at last an admission that you don't know very much about aeroplanes. Progress at last! </div></BLOCKQUOTE>

You said:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">LOL!

Never said I was!

Would love to see you quote me where I did!

But.. you wont!

Why?

Because I never did!
</div></BLOCKQUOTE>

Now, that just doesn't make grammatical sense as a reply to my post. You perhaps meant to say that you never claimed to be an expert in aeronautical matters, but were again let down by your poor English skills?

If so, why is it that you see fit to post in, and indeed create, technical threads regarding matters of aircraft performance?

Why is it that you see fit to launch attacks upon the technical work of others based upon the (almost invariably ill-founded) assumption that your interpretation of technical source material is the only correct interpretation?

Why do you continue to respond with such an arrogant and dismissive attitude to the best efforts of those around you to educate you?

TheycallhimJosh
04-02-2007, 02:38 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">You stop following me around in every thread and you will solve the problem yourself </div></BLOCKQUOTE>-AKA TAGERT
You stop posting UNPROVOKED,insulting remarks as if you were some kind of Real TOUGH guy...Moderators Ban Him NOW.

AKA_TAGERT
04-02-2007, 03:42 PM
Poooor Nancy!

AKA_TAGERT
04-02-2007, 03:43 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Now, that just doesn't make grammatical sense as a reply to my post. You perhaps meant to say that you never claimed to be an expert in aeronautical matters, but were again let down by your poor English skills?

If so, why is it that you see fit to post in, and indeed create, technical threads regarding matters of aircraft performance?

Why is it that you see fit to launch attacks upon the technical work of others based upon the (almost invariably ill-founded) assumption that your interpretation of technical source material is the only correct interpretation?

Why do you continue to respond with such an arrogant and dismissive attitude to the best efforts of those around you to educate you? </div></BLOCKQUOTE>Nice Spin Doctor!

Looks like your muddy waters skills that you prefected in the P47 thread are starting to pay off!

But I am sure most people see right though it.. As they did in the P47 thread

Viper2005_
04-02-2007, 05:51 PM
Interesting that you accuse me of spin and neatly sidestep the questions raised in my post...

BTW did you read the material I posted regarding FTH?

AKA_TAGERT
04-02-2007, 06:31 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Interesting that you accuse me of spin and neatly sidestep the questions raised in my post...

BTW did you read the material I posted regarding FTH? </div></BLOCKQUOTE>Nice Spin Doctor!

Looks like your muddy waters skills that you prefected in the P47 thread are starting to pay off!

But I am sure most people see right though it.. As they did in the P47 thread

TheycallhimJosh
04-02-2007, 07:05 PM
It looks like AKA ***gert is at it again,posting with other names to back himself up and insult people,you are really a pathetic loser,Taggert or whatever you're calling yourself nowadays...

AKA_TAGERT
04-02-2007, 07:19 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TheycallhimJosh:
It looks like AKA ***gert is at it again,posting with other names to back himself up and insult people,you are really a pathetic loser,Taggert or whatever you're calling yourself nowadays... </div></BLOCKQUOTE>Pooor Paranoid Nancy

TheycallhimJosh
04-02-2007, 08:58 PM
It's miraculous what a friend with a dictionary can do for you ***gert.Good job on "paranoid".Now have him look up "pooor"...

AKA_TAGERT
04-02-2007, 09:23 PM
Sounds like someone needs a hug?

beaverscout
04-02-2007, 11:20 PM
Tagert, that Josh dude must not know your the best looking one in the squad. I have been wanting a hug from you for a long time now. What's up with that??? hug a thug huh??

AKA_TAGERT
04-03-2007, 07:24 AM
ROTFL!

On that note, the next time you come near Las Cruces you beter plan on stoppin by!

Bring Jose too.. tell him to bring MY SHOE!

JtD
04-03-2007, 08:45 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AKA_TAGERT:

The point both of your are missing is the in-game MP gauges are just for show and do not factor into the actual performance of the engine and thus the plane. Oleg only goes by two settings.. 100% and 110% throttle settings. </div></BLOCKQUOTE>

How do you know that I am missing that point? Your arrogance told you so?

Just to make sure the next time you claim this it is not a wrong assumption, but defamation:

I know that point. I have been there two years ago.

AKA_TAGERT
04-03-2007, 09:34 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
How do you know that I am missing that point? Your arrogance told you so?

Just to make sure the next time you claim this it is not a wrong assumption, but defamation:

I know that point. I have been there two years ago. </div></BLOCKQUOTE>If believing that helps you get to sleep at night, so be it! Your ignorance is no concern of mine!

As for arrogance.. I am one of the few here who has an ego that allows one to admit a mistake.

Thus the arrogance shoes fit you and yours better than I.

Viper2005_
04-03-2007, 10:16 AM
Getting back to topic, the correct test procedure would be to set 110% throttle + WEP to give 3700 rpm/+9 psi at sea level.

Then climb at the correct IAS, changing supercharger gears either at 8700 feet, ignoring the boost gauge if you don't believe it, or +4 psi boost if you want to replicate the documented test methodology.

AKA_TAGERT
04-03-2007, 10:26 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Getting back to topic, the correct test procedure would be to set 110% throttle + WEP to give 3700 rpm/+9 psi at sea level.

Then climb at the correct IAS, changing supercharger gears either at 8700 feet, ignoring the boost gauge if you don't believe it, or +4 psi boost if you want to replicate the documented test methodology. </div></BLOCKQUOTE>Which is what I did..

Except I did make one mistake

I switched from MS to FS at 10kft intead of at 8700ft!

I was looking at the table which shows MS still being used at 8,700ft.

But..

I missed the note at the top of the table that says

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Supercharger gear changed when boost in M.S. gear fell to +4 lb/sq.in. </div></BLOCKQUOTE>

And per the real world data in the table the +4lb/sq.in does occur at 8,700ft.

On that note.. above 'that' note.. it says

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">During the tests the air temperatures in the neighbourhood of the FS gear full throttle height differed from ICAN standard by between 0 and -10C. </div></BLOCKQUOTE>
Assuming that the ICAN standard means std conditions it sounds like this data may not have been adj to std values?

Which may explane the difference between real world data and ingame results.

All in all Ill re-run the test and switch the gear at 8,700ft instead of 10,000ft!

Good eye Viper! Thanks for catching that!

Just to highlight why we should NOT use the MP guage.. Take a look at the ingame data in my graph (red line)
http://www.geocities.com/grantsenn/NACA_TESTING/ANALYSIS/TEST_TYPE/ROC/408/TEMPEST/ME_01/MP.JPG
It has not even dropped down to +4lb/sq.in yet at 10kft.. Where I switched the SC.. and at 8,700ft it is around +5lb/sq.in. So in essance, my mistake resulted in me doing it by the MP guage anyways! Which factored into me 'beliving' 10kft was the correct alt to switch the SC at.. but that note above the table clearly implys it happened at 8,700ft

Also.. dont put too much credit in that graph.. In that I had to convert from DeviceLink 'ata' to 'lb/sq.in' and there was no direct scale fator to do that (crosses through zero).

Thus I had to come up with a function to convert it and that was via a linear fit of a chart I have that shows US, RAF, German and JAP values but does not have a whole lot of resolution.

So, Ill take another look at that too to make sure it is providing the correct values, in that I had to tweak the linear fit to get it to report +9.0lb/sq.in to correctly.

But..

I didnt have a 2nd point to verify that the tweak didnt mess it up at some other point.. So there coud be some error in that +4lb/sq.in value listed. What with Oleg stating the guages are all for show.. I didn't worrie about it too much.. but now that you and others are showing so much interst in these WAGS I guess I can go back and make sure my WAG of the WAG does not confuse anyone! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

JtD
04-03-2007, 12:40 PM
If we are to believe your climb data the boost data is pretty much correct. Both of the graphs show that the Tempest in game has a too high FTH in both charger gears.

The best way to tell the correct point to change gears is to make two climbs, one in low blower one in high blower and check where the graphs cross.

AKA_TAGERT
04-03-2007, 12:52 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
If we are to believe your climb data the boost data is pretty much correct. Both of the graphs show that the Tempest in game has a too high FTH in both charger gears.

The best way to tell the correct point to change gears is to make two climbs, one in low blower one in high blower and check where the graphs cross. </div></BLOCKQUOTE>So let me see if I understand you correctly.. Your saying do two tests.. One for SC set low and one for SC set high.

Both starting from sea level up to ~35kt.. Where you set the SC at sea level and leave it set to that value for the whole climb.. Never changing it.

Assuming that is the case

Than what we would be able to do is comp the re****s to the RWD?

For example, for the SC set to low and left low we should see the performance drop off at some altitude (around the 8700 mark) and for the SC set to high case it should be crappy at first, and than improve at some altitude (around the 8700 mark?)

Is that the jist of it?

JtD
04-03-2007, 01:03 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AKA_TAGERT:

Than what we would be able to do is comp the re****s to the RWD? </div></BLOCKQUOTE>

Well, yes and no. I'd suggest this method to find the altitude where you change sc into next gear. I actually think you already got it pretty well in your first try, so it might not be necessary in this particular case. But if you did, you'd check the two climbs to find the point and do a third where you change gear at that point (in fact, if you do the math, a little bit lower than where the lines on the paper cross).

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">For example, for the SC set to low and left low we should see the performance drop off at some altitude (around the 8700 mark) and for the SC set to high case it should be crappy at first, and than improve at some altitude (around the 8700 mark?) </div></BLOCKQUOTE>

In general, yes. Only that the low SC is starting to lose power already at about 4000' according to your chart and the high gear is losing steam below 15000'. These lines would roughly be extrapolated up and down resp.

Viper2005_
04-03-2007, 01:30 PM
http://www.wwiiaircraftperformance.org/tempest/sabrecurve.jpg

Note that this chart is based upon 400 mph ram, and therefore exhibits higher FTHs than would be expected in the climb case.

It might be sensible to carry out some speed trials to investigate the modelling of ram effect in the game...

As for the climb test method suggested by JtD, here is a climb chart for the P-51D constructed as he suggests:

http://www.wwiiaircraftperformance.org/mustang/p-51b-24771-climb-blue.jpg

Needless to say, the same principles may also be applied to speed testing.

AKA_TAGERT
04-03-2007, 02:43 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
Well, yes and no. I'd suggest this method to find the altitude where you change sc into next gear. I actually think you already got it pretty well in your first try, so it might not be necessary in this particular case. But if you did, you'd check the two climbs to find the point and do a third where you change gear at that point (in fact, if you do the math, a little bit lower than where the lines on the paper cross). </div></BLOCKQUOTE>

Ok, so maybe that didn't make it as clear as I hoped?

Let's go back to your 'cross over' statement..

Do the two tests and than compare the point at which the two 'graphs cross over.

Now the question is.. Which graphs?

1) ROC
2) MP

My guess is you were refering to the MP? But I am worried that due to the guages being only for show.. We may want to consider the ROC? Granted, it is a guage that is for show too.. But I can validate the ROC (read var value in DeviceLink) with the dx/dt of the altitude. Granted the alitude is a guage too.. but it can be validated to the Wonder Woman altitude dsiplay that Oleg says is valid (read NOT for show). I have checked the WW alt vs DeviceLink alt and for the most part they are good to go!

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
In general, yes. Only that the low SC is starting to lose power already at about 4000' according to your chart and the high gear is losing steam below 15000'. These lines would roughly be extrapolated up and down resp. </div></BLOCKQUOTE>
Roger..

Keep in mind, my goal is to see how well the in-game Tempest acts like the real thing when you fly it like it was flown during the tests..

Where as this cross over test is more of a find the ingame SC sweat spot.. Which is a interesting side note but not the orginal goal.

JtD
04-03-2007, 03:06 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AKA_TAGERT:
Now the question is.. Which graphs?

1) ROC
2) MP </div></BLOCKQUOTE>

ROC.

(MP should be 9lbs all the way up to 15k in high alt sc.)

AKA_TAGERT
04-03-2007, 03:33 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AKA_TAGERT:
Now the question is.. Which graphs?

1) ROC
2) MP </div></BLOCKQUOTE>

ROC.

(MP should be 9lbs all the way up to 15k in high alt sc.) </div></BLOCKQUOTE>Ah.. Good point!

So.. time premiting Im going to re do the Tempest test tonight per the real world test..

But..

If you want to do those other two tests I don't mind processing them for your.. I know you can do it too.. but If I process them than we can compare the graphs to the tests I do in that they will all be the same scale and such.

AKA_TAGERT
04-03-2007, 09:27 PM
Well I re-did the test.. the results were not that different..

But..

For some reason my prop pitch was changing on it's own this time, even though I didnt touch it.. So Im going to re-run the test again tommorow and see if maybe I bumped the pp handle (it is on a slier) when I adj the trim..

FA_Whisky
04-05-2007, 09:18 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> If we are to believe your climb data the boost data is pretty much correct. Both of the graphs show that the Tempest in game has a too high FTH in both charger gears.

The best way to tell the correct point to change gears is to make two climbs, one in low blower one in high blower and check where the graphs cross. </div></BLOCKQUOTE>

There is one problem. You'll have to test it for different throttle settings with and without WEP. I did a level speed test with 90% throttle without WEP. The best alt to switch the supercharger there is around 4700 meters. (14.000ft)

Brain32
04-05-2007, 09:26 AM
@TAGERT check this thread at CWOS: http://www.acompletewasteofspace.com/modules.php?name=F...le=viewtopic&t=12832 (http://www.acompletewasteofspace.com/modules.php?name=Forums&file=viewtopic&t=12832)
Might be helpfull...

AKA_TAGERT
04-05-2007, 10:34 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Brain32:
@TAGERT check this thread at CWOS: http://www.acompletewasteofspace.com/modules.php?name=F...le=viewtopic&t=12832 (http://www.acompletewasteofspace.com/modules.php?name=Forums&file=viewtopic&t=12832)
Might be helpfull... </div></BLOCKQUOTE>Man..

Another informative CWOS thread! I need to start checking there more often!

thanks for the link Brian!

Nice to see that LesniHU is getting the same ROC 'shape' that I am getting.

Xiolablu3
04-06-2007, 08:22 AM
Nice attempt at tests. I am actually surprised at how close the figures are to the real thing!

After all we are in a perfect situation in a sim with almost no wind and a 'perfect' plane.

The curves are almost perfect.

JG14_Josf
04-06-2007, 11:28 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">-No big surprise here, light plane accelerates faster, heavy (especially with droptanks) slower. </div></BLOCKQUOTE>

To whom it may concern:

The above comment was cut from the ˜acceleration (http://lesnihu.wz.cz/FM/Tempest/TempestVaccel_000.html) test' web page. Those charts begin acceleration data from 400 km/h and 1000 feet altitude.

Even if the altitude/density of the air is not compressible at 1000 feet the speed at which the tests begin is almost certainly starting above the minimum drag speed.

In other words the test begins at a speed were total drag is climbing steeply due to parasite drag increasing at a rate square with velocity. Of course parasite drag increases square with velocity from zero airspeed on the runway; however – Induced drag is very high at the moment the plane takes-off from the runway. The total drag force load at slow speed is dominated by induced drag (1 g load = level flight) and the induced drag force load declines to almost no drag at top speed. Therefore the total drag force load in level flight is least somewhere between the decline of induced drag force and the increase of parasite drag force (including trim drag force).

Example: (http://www.allstar.fiu.edu/AERO/BA-Form&gra.htm)

http://www.allstar.fiu.edu/AERO/images/e7low.gif

75 knot = 138.9 kilometer/hour

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Figure 7. How drag varies with air speed for a Cessna 172, flaps up, 2400 lbf, at MSL. </div></BLOCKQUOTE>

The rate of acceleration from the minimum drag speed should be a steady decline as the rate of acceleration decreases with speed FROM the minimum drag speed.

Starting and the minimum drag speed during an acceleration test will be a steady decrease in the rate of acceleration as Total Drag Force increases (Parasite and trim drag – don't forget about trim drag which may be increasing rapidly as the pilot has to trim out the need to push the stick forward).

From the speed of minimum drag the rate of acceleration is also reduced as prop thrust reduces.

http://www.allstar.fiu.edu/AERO/images/e4low.gif
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Figure 4. Thrust, drag, and their difference (excess thrust), as functions of air speed, for a Cessna 172 at sea level, flaps up, weighing 2400 pounds. </div></BLOCKQUOTE>

As total drag increases from the minimum drag speed the total thrust decreases setting up a diminishing rate of acceleration as power required increases and power available decreases. In other words the rate of acceleration is decelerating for two reasons. Meanwhile the factor of induced drag (in level flight) is diminishing.

Contention:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">-No big surprise here, light plane accelerates faster, heavy (especially with droptanks) slower. </div></BLOCKQUOTE>

In a vacuum there is no big surprise that a higher mass object requires more power to accelerate the mass. What cannot be ignored when flying trough air is the decrease in drag loading for the same aircraft gaining internal mass.

Example:

Drop an empty drop tank and a full drop tank from the same height and see which drop tank hits the ground first.

Better yet:

Fly two planes side by side in a vertical dive at 400 km/h and release a drop tank from each plane where one drop tank is empty and the other drop tank is full.

Assuming that both drop tanks will not tumble (and even if they both tumble) there will be a significant difference in the rate of NET acceleration after the two drop tanks are released into air mass at 400 km/h.

Assuming two identical planes flying exactly the same flight condition with one exception where one plane has more internal mass (full fuel) and the other plane having less fuel (almost empty) the rate of acceleration from 400 km/h to the top speed of the slowest plane will be determined by the plane with the higher top speed. Since the heavy plane will be flying at a higher angle of attack the heavier plane will have a higher force of induced drag (which is minimal at top speed in level flight) and therefore the added weight will decrease the Top Speed of the heavy plane.

Of course, no big surprising, the added weight reduces level flight top speed and therefore reduces level flight acceleration from 400 km/h up to top speed.

What happens to Top Speed when both planes are pitched over into a shallow dive?

Answer:

The opposite of what happens when both planes are pitched up into a shallow climb.

In other words the more massive plane reduces the induced drag penalty and gains the parasite drag advantage. In other words the TERMINAL velocity or Top Speed in the dive of the more massive plane increases at a faster rate (as dive angle increases) compared to the same plane loaded lighter (internal mass = density).

Pitching up is the opposite. The more massive plane (all else being equal) increases the induced drag penalty and decreases the parasite drag advantage because top speed is lowering.

Pitching down increases the ability of the higher mass plane to move air mass due to inertia (greater density) while lowering the penalty of induced drag resulting first in a dive angle where both planes have the same top speed and as the dive angle increases the heavier plane will gain a higher top speed and THEREFORE a higher rate of acceleration to that top speed at that angle of dive especially when the dive is started FROM the minimum drag speed.

On the other hand: if the acceleration test is started at the 1 g stall speed (both planes side by side will have to start the acceleration test at the heavy planes 1 g stall speed because the heavy plane will have a higher 1 g stall speed), then, both planes will be contending with extreme limits of induced drag and the rate of acceleration FROM the 1 g stall speed will gain in rate of acceleration FROM the 1 g stall speed as induced drag lowers and while engine produced thrust is nearly at the maximum peak thrust.

Therefore the graph of acceleration should look similar to an upside down Total Drag Chart where the rate of acceleration starts out slow and the rate of acceleration increases up to a peak (equal or near the minimum drag speed peak) and above the minimum drag peak the rate of acceleration will decline again.

There is an easy method of testing the differences in acceleration caused by parasite drag upon the higher mass plane compared to the lower mass (lower density) plane (all else being equal).

The test is easy.

As both planes are starting their acceleration test, side by side, where one Tempest (or any plane) is flying next to another Tempest, one plane has full fuel, the other plane has almost empty fuel (internally), and both planes accelerate to the slower top speed (the heavier plane), as this happens and as the lighter Tempest accelerates faster to the heavy plane top speed, where both pilots are looking at each other's plane, then, once at the top speed of the heavy plane, both planes side by side again, the lighter Tempest with his throttle pulled slightly back, then, both pilots chop the throttle to see which plane reaches the 400 km/h starting speed first, AND, keep on decelerating to see which plane stalls first – an easy test.


More info on increased weight (http://flighttest.navair.navy.mil/unrestricted/FTM108/c5.pdf)

Scroll down to 5.3.5.2 INCREASED GROSS WEIGHT

I don't yet know how to cut and past .pdf Charts (lucky you).

Scroll to Figure 5.8 EFFECT OF INCREASED GROSS WEIGHT ON SPECIFIC EXCESS POWER

Note the effect of increased weight on TOP SPEED compared to the effect of increased weight on the 1 g stall speed. The increase of weight lowers the Top Speed (Ps = 0) less than the increased weight increases the 1 g stall speed (Ps = 0). The difference is significant for a reason.

What has this to do with IL2 and WWII fighter combat in general?

In a level flight drag race between three planes:

Spitfire VB
P-47D
Fw190A-5

If the race is started above the minimum drag speed (somewhere between best climb speed and corner velocity), then, the plane that should accelerate faster will be the plane with the higher top speed.

If the race is started at the 1 g stall speed for the plane with the highest 1 g stall speed, then, the winner (as always will be the case) is the plane with the higher Ps at that speed.

In other words: The acceleration race from a 1 g stall speed will show a whole lot more about the relative excess power performance than will an acceleration race from 400 km/h.

Examples abound in the historical record proving that the P-47 accelerated fastest in the dive (with the possible exception of the Me 262); however – what was the initial starting speed?

Example:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
STABILITY AND CONTROL SUB-COMMITTEE.
AERONAUTICAL RESEARCH COMMITTEE
The P-47 Versus FW-190 at Low Altitude
Communicated by D.S.R. , M.A.P.

Objective.
1. Comparative performance tests were conducted between the P-47 and the Fw-190, for the purpose of ascertaining just what the P-47 airplane could do in combat against the Fw-190 at low altitude, and to aid the P-47 pilots in their initial encounters with those enemy planes.

(a) Acceleration:

(1) 210 m.p.h. to 275 m.p.h. at 2000 ft: The Fw-190 accelerated faster than the P-47 and gained approximately 200 yeards.
(2) 210 m.p.h. to 275 m.p.h. at 5000 ft: Results were the same as at 200 feet.
(3) 200 m.p.h. to full power at 500 ft: The FW-190 accelerated faster that [sic] the P-47 initially and gained about 200 yards, but at a speed of 330 m.p.h. the P-47 rapidly overtook the FW-190 and gained about 2000 yards very quickly and was still accelerating. Water injection was used by the P-47.
(4) 220 m.p.h. to 300 m.p.h with full throttle at 15,000 ft: Again the FW-190 initially gained about 200 yards but the P-47 quickly overtook it. The FW-190 high speed supercharger cut in automatically at this altitude, and this supercharger seemed to cut in at lower altitudes when a speed in excess of 340 m.p.h. was attained by diving.
</div></BLOCKQUOTE>

Contention: There are fewer surprises once all the variables are accounted for accurately.

Light plane, in that case, did not always accelerate faster.

Xiolablu3
04-06-2007, 12:04 PM
Nevermind.

Decided I dont know enough about it to comment really.

AKA_TAGERT
04-06-2007, 02:51 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Xiolablu3:
Nice attempt at tests. I am actually surprised at how close the figures are to the real thing!

After all we are in a perfect situation in a sim with almost no wind and a 'perfect' plane.

The curves are almost perfect. </div></BLOCKQUOTE>Oleg's sim never ceases to amaze me at how well it hits some numbers.. like the ROC, and how far off some numbers are.. like the Roll Rates.

All in all the best WWII sim made to date! RM wise, and most likely for some time to come!

AKA_TAGERT
04-06-2007, 10:09 PM
I just updated the Tempest test at airwarfare

Enjoy