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View Full Version : Oleg Please look at dispersion of P-47 Guns



XyZspineZyX
10-03-2003, 10:24 AM
Salute Oleg

I have tested and tested the P-47, and it is clear to me there is an error in how the aircraft's weapons are modelled.

Yes, you can destroy at target, but only at the exact moment when ALL guns converge. Outside of the 'magic' convergence range, the weapons are basically useless, and do very little damage. The bullets impact in a wide pattern, and have no concentrated effect.

They are modelled as if all the 8 guns are spraying a pattern 10 feet wide. Which is not correct.

There should be two concentrated streams of fire coming out of the P-47. Yes, when these two streams converge, they will be more powerful, but even when they are not converging, and a single stream hits a target, they are concentrated.

Each of the wings has firepower equivalent to the armament of a 109F4 or G2. And more tightly grouped.

Please look at this photograph:

http://www.ipmsstockholm.org/photos/detail_p47_08.jpg


There is less distance between the guns on this wing than there is between the guns in the nose of a 109G2.

And the weight of the bullets fired and the power is more than the above mentioned 109.

Yet, we find that a 109 does much more damage.

Please look at this site:

http://www.quarry.nildram.co.uk/WW2guneffect.htm

This is the site of Tony Williams, an acknowledged and published expert in WWII Fighter Aircraft armament.

I will be using his formulas for my calculations.


Single P-47 Wing of four .50 calibre guns:


A .50 calibre Armour Piercing Inciendary bullet weighs 43 grams and can be fired at 13 rounds per second.

Each second, each wing of a P-47 throws 2.236 kilograms of weight at 890 Meters per second for a Momentum factor of 1990.04

Taking into account the High Explosive content of the bullets, which is 2% and using Williams formula, we multiple the effect by 1.2 for a total Power of 2388.05


109G2 nose weapons:


A MG17 bullet weighs 12.89 grams and syncronized, fires at 18 rounds per second.

A MG151/20 bullet weighs either 117 grams for API or 115 grams for High Explosive. (no Minegeschvoss for G2) Typically they were loaded in that order for an average of 116 grams. They fire at 12 rounds per second unsyncronized.

Each second a 109G2 throws .464 kilograms of 7.92mm at 755 meters per second for a Momentum factor of 350.32. There is no HE content in a 7.92 bullet so the Power is 350.22.

Each second a 109G2 throws 1.392 kilograms of 20mm at 720 meters per second for a momentum factor of 1002.24. Multiple this by 1.315, (HE content of API was 3.1, for HE was 3.2) and we have a Power of 1317.94

Total Power 1668.17

Using Williams calculations, each wing of a P-47 is 143% more powerful than the total firepower of a 109G2.

Please adjust the effectiveness of the P-47's weapons.


Thankyou for your patience

RAF74 Buzzsaw

XyZspineZyX
10-03-2003, 10:24 AM
Salute Oleg

I have tested and tested the P-47, and it is clear to me there is an error in how the aircraft's weapons are modelled.

Yes, you can destroy at target, but only at the exact moment when ALL guns converge. Outside of the 'magic' convergence range, the weapons are basically useless, and do very little damage. The bullets impact in a wide pattern, and have no concentrated effect.

They are modelled as if all the 8 guns are spraying a pattern 10 feet wide. Which is not correct.

There should be two concentrated streams of fire coming out of the P-47. Yes, when these two streams converge, they will be more powerful, but even when they are not converging, and a single stream hits a target, they are concentrated.

Each of the wings has firepower equivalent to the armament of a 109F4 or G2. And more tightly grouped.

Please look at this photograph:

http://www.ipmsstockholm.org/photos/detail_p47_08.jpg


There is less distance between the guns on this wing than there is between the guns in the nose of a 109G2.

And the weight of the bullets fired and the power is more than the above mentioned 109.

Yet, we find that a 109 does much more damage.

Please look at this site:

http://www.quarry.nildram.co.uk/WW2guneffect.htm

This is the site of Tony Williams, an acknowledged and published expert in WWII Fighter Aircraft armament.

I will be using his formulas for my calculations.


Single P-47 Wing of four .50 calibre guns:


A .50 calibre Armour Piercing Inciendary bullet weighs 43 grams and can be fired at 13 rounds per second.

Each second, each wing of a P-47 throws 2.236 kilograms of weight at 890 Meters per second for a Momentum factor of 1990.04

Taking into account the High Explosive content of the bullets, which is 2% and using Williams formula, we multiple the effect by 1.2 for a total Power of 2388.05


109G2 nose weapons:


A MG17 bullet weighs 12.89 grams and syncronized, fires at 18 rounds per second.

A MG151/20 bullet weighs either 117 grams for API or 115 grams for High Explosive. (no Minegeschvoss for G2) Typically they were loaded in that order for an average of 116 grams. They fire at 12 rounds per second unsyncronized.

Each second a 109G2 throws .464 kilograms of 7.92mm at 755 meters per second for a Momentum factor of 350.32. There is no HE content in a 7.92 bullet so the Power is 350.22.

Each second a 109G2 throws 1.392 kilograms of 20mm at 720 meters per second for a momentum factor of 1002.24. Multiple this by 1.315, (HE content of API was 3.1, for HE was 3.2) and we have a Power of 1317.94

Total Power 1668.17

Using Williams calculations, each wing of a P-47 is 143% more powerful than the total firepower of a 109G2.

Please adjust the effectiveness of the P-47's weapons.


Thankyou for your patience

RAF74 Buzzsaw

XyZspineZyX
10-03-2003, 11:31 AM
Wing vibration and derormation under load - thats the root of problem. We can only estimate the dispertion of the bullets firing under these conditions. Only 1 thing we can say for sure: dispertion of wing guns should be much greater than dispertion of nose guns - even not counting convergence.

XyZspineZyX
10-03-2003, 11:45 AM
- Each of the wings has firepower equivalent to the
- armament of a 109F4 or G2. And more tightly
- grouped.
-

Hmm, if their guns are as effective as G2's of F4's take a look of these tracks:

109 vs LaGG-3 compare (http://www.pcuf.fi/~arzi/beschusstest.zip)

They are not mine, I found then SITS some week ago. For my shame I have forgotten his nick/lost this thread. I apologize the originator for that. However these 1.11 tracks are quite revealing and if that is correct then .50 cal must be too if their combination is only 2 times as powerful...

Oh, bit off-topic to lighten the mood, but please note inline engine durability in separate planes too in arcade mode. I find it funny as h e l l.

XyZspineZyX
10-03-2003, 11:49 AM
Hmmm...you should try using the Hurricane Mk1's 8 brownings to kill something...bloody hopeless.

S/Ldr. Ginger,
C.O. - No.601 Fighter Squadron, Auxiliary Air Force.

http://www.nzfpm.co.nz/images/small/airtoair14.jpg


The Tangmere Pilots - http://www.tangmere-pilots-raf.co.uk/

XyZspineZyX
10-03-2003, 12:06 PM
Chromatorg wrote:
- Wing vibration and derormation under load - thats
- the root of problem. We can only estimate the
- dispertion of the bullets firing under these
- conditions. Only 1 thing we can say for sure:
- dispertion of wing guns should be much greater than
- dispertion of nose guns - even not counting
- convergence.


There is similar dispersion for Brewster guns, and it's guns are in the fuselage and wing roots.

.50 cal just disperses, rightfully or not, I don't know.

What comes to gun comparison, try LaGG-3 '41 following QMB setup:

4 He-111, 4 Ju-88 and 4 Bf-110 all on veteran, then see how many you can shoot down. My quick absolutely unsientific test I got 7 kills in LaGG, 5 kills in 190 A-9, and 2 kills in P-47. /i/smilies/16x16_smiley-happy.gif

LaGG-3 '41 has one 12.7mm, 2 7.62mm and one 20mm cannon. /i/smilies/16x16_smiley-happy.gif

Really makes you want to laugh! /i/smilies/16x16_smiley-happy.gif And talk about dispersion too! /i/smilies/16x16_smiley-wink.gif /i/smilies/16x16_smiley-very-happy.gif


-jippo

Ps. My first half a second burst in LaGG from straight 6 o'clock against Ju-88 blew it's engine cleanly off!! /i/smilies/16x16_smiley-very-happy.gif



Message Edited on 10/03/0311:19AM by Jippo01

XyZspineZyX
10-03-2003, 12:18 PM
Jippo01 wrote:
- LaGG-3 '41 has one 12.7mm, 2 7.62mm and one 20mm
- cannon.

They got 2x12.7mm, 2x7.62mm and 1x20mm.

XyZspineZyX
10-03-2003, 12:23 PM
Cappadocian_317 wrote:
-
- Jippo01 wrote:
-- LaGG-3 '41 has one 12.7mm, 2 7.62mm and one 20mm
-- cannon.
-
- They got 2x12.7mm, 2x7.62mm and 1x20mm.

Oh, really? Weeell, that explains it then! /i/smilies/16x16_smiley-very-happy.gif


Honestly speaking, object viewer disagrees with you. I haven't counted the guns but OV says 4 guns. /i/smilies/16x16_smiley-happy.gif


-jippo

XyZspineZyX
10-03-2003, 12:50 PM
In the game they got 5 guns in the nose, but that is just a small thing and not the issue here.

As for the P47 test, I just completed it and killed all 12 planes and I had ammo to spare.
I will do it again with a standard ammo load next time since I always fly with the extra ammo option.
I don't know how much extra ammo is added but it holds a lot with this option.

The guns do spread a lot at distance and I have no idea if this is correct or not but I always fire from close range and my guns are set to 200 meters.
Heinkels got weak outer wings and the engines catch fire really fast, the same for the Ju88's and the Bf110's.

Just aim at the engines and make sure one side of your guns hit the engine and the other side the outer wing part and you only need one or two bursts to shoot it down.

XyZspineZyX
10-03-2003, 12:52 PM
Jippo01 wrote:
- Cappadocian_317 wrote:
--
-- Jippo01 wrote:
--- LaGG-3 '41 has one 12.7mm, 2 7.62mm and one 20mm
--- cannon.
--
-- They got 2x12.7mm, 2x7.62mm and 1x20mm.
-
- Oh, really? Weeell, that explains it then! /i/smilies/16x16_smiley-very-happy.gif
-
-
- Honestly speaking, object viewer disagrees with you.
- I haven't counted the guns but OV says 4 guns. /i/smilies/16x16_smiley-happy.gif
-
-
--jippo
-
-


There are number of errors errors in OV, it looks that one group of people was making the game and another OV! Not counting numerous typos, errors include Lagg-3 (2*12,7 UB, one in OV), Mig-3 AM-38 (one UB, 2 in OV), Yak-7b (2*12,7 UB, 2*7,62 ShKAS in OV), P-39Q-1 (2*12,7 Mgs in wing, 2*7,62 in OV), Yak-1 (2*7,62 ShKAS, only one in OV), Yak-9, 9D (UB, ShKAS in OV), Fw190A4 (MGFFs in wings, no mention in OV)...

XyZspineZyX
10-03-2003, 12:52 PM
You wouldn't have a track, would you? /i/smilies/16x16_smiley-wink.gif

How did you do with the LaGG? /i/smilies/16x16_smiley-happy.gif 16?



-jippo

XyZspineZyX
10-03-2003, 01:02 PM
Structure of the P-47's wing from Zeno's site

http://rwebs.net/avhistory/images/wing.jpg

The text

"Main members of the wing are the two main spars which support attachment of the wing to the fuselage and three auxiliary spars, one each supporting the aileron and flap and the other supporting the landing gear.

Main spars are constructed of E-shaped cap strips riveted to webs of varying thickness from a minimum of .032" for the outboard web of both spars to a maximum of .250" thickness for the inboard web of the forward main spar. Both main spars are reinforced at suitable intervals by extruded angles which also serve as anchors for frame installations.

Inboard ends of the main spars of each wing are fitted with a pair of wing hinges which are pinned to the mating fuselage hinges by split bushings; tapered bolts expand these bushings to a tight fit, thus securing positive attachment.

The aft auxiliary spars support the movable surfaces and are constructed of angle cap strips and webs of .072" to .025" thickness. The landing gear auxiliary spar, since it is subjected to landing loads, is of somewhat heavier construction-namely, .091" web and is reinforced similar to the main spars.

Flanged ribs of alclad 24-ST are secured between spars at the angle stiffeners. Ribs vary from .051 to .032 with the exception of the root chord rib and gun bay partitioning ribs; the root chord rib is .064" and the gun bay partitioning ribs of .064".

Nose and trailing edge ribs are flanged and are also of Alclad 24-ST."


Looks rather a solid construction to me./i/smilies/16x16_smiley-wink.gif


http://www.stenbergaa.com/stenberg/west-battleline.jpg



"Only a dead 'chamber pot' is a good 'chamber pot'!"

Message Edited on 10/03/0308:12AM by MiloMorai

XyZspineZyX
10-03-2003, 01:37 PM
Next time I record a track of it.

I didn't fly with the LaGG3 1941 yet, personally I don't like this craft.

There are only a few type of planes I really enjoy to fly.

The P47's
The Hurricanes
The LaGG3 1943 (Sometimes)
The IL2's

Waiting for the Spitfires and the Tempest, oh and the P38. /i/smilies/16x16_smiley-happy.gif

On the German side I like the Bf109 Emils, the F4 and the G2.

XyZspineZyX
10-03-2003, 01:43 PM
Cappadocian_317 wrote:
- Next time I record a track of it.


Please do, you must have some pretty good tactic since you get 12 kills. I only got smoking engines on my plane. Not a chance to get, say even 4 planes. And I use 150m convergence. /i/smilies/16x16_smiley-happy.gif

Admitted that I never was a ace, not to mention P-47 ace.

But I would really like to see your tactic, so please make a track for me. /i/smilies/16x16_smiley-happy.gif


-jippo

XyZspineZyX
10-03-2003, 02:05 PM
wing MG dispersion? take MiG3ud with UBK gondolas... no dispersion /i/smilies/16x16_smiley-wink.gif
let´s see how P-38s nose concentrated weapons will do..

basically, we are spoiled by overmodelled UB machinegun. No dispersion, no bullet slowdown, flat trajectory over 1 km and armour penetrability like MK103. I can blow armored Russian car with single UB.



<center>http://www.kurita.sk/PRIVATE/pictures/sig_il2.jpg

Hunter82
10-03-2003, 02:37 PM
Basically to put it in laymans terms the brownings would create a hole in a panel about the size of 1 inch in relation a 7.92 should make a hole roughly 1 X greater. The size references are just for example and are not an accurate aspect ratio.

I do not have technical data to provide so I rarely comment on the subject. I have however seen video tape,mountains of pictures of ballistics tests with each weapon on panel sub-sections with each and the results were contrary to what is represented currently in IL2 and FB IMO. I think overall loses in the BoB show the record to be true as most 109 were limited to 7-14 minutes of engagment due to fuel issues while the Hurri and Spit could engage at will.




No601_Ginger wrote:
- Hmmm...you should try using the Hurricane Mk1's 8
- brownings to kill something...bloody hopeless.
-
- S/Ldr. Ginger,
- C.O. - No.601 Fighter Squadron, Auxiliary Air Force.
-
<img
- src="http://www.nzfpm.co.nz/images/small/airtoair1
- 4.jpg">
-
-
- The Tangmere Pilots - <a
- href="http://www.tangmere-pilots-raf.co.uk/"
- target=_blank>http://www.tangmere-pilots-raf.co.uk
- /</a>



=======================================
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XyZspineZyX
10-03-2003, 02:44 PM
Thanks Milo, I was just gonna dig for a pic like that. I can't believe everyone jumps on this wing flex crap. The P-47 was heavier than the freakin IL2 for god's sake. And it's because of all the metal used in it's construction. It should easliy be as tough as an IL2, but, certainly wing flex is NOT the problem here.

XyZspineZyX
10-03-2003, 03:58 PM
"High explosive content of the shells"?
what high explosive content are we talking about?
I agree completely about the divergence isssue BTW-
S!

http://members.cox.net/miataman1/WAR-08.jpg

XyZspineZyX
10-03-2003, 04:49 PM
BlitzPig_DDT wrote:
- Thanks Milo, I was just gonna dig for a pic like
- that. I can't believe everyone jumps on this wing
- flex crap. The P-47 was heavier than the freakin IL2
- for god's sake. And it's because of all the metal
- used in it's construction. It should easliy be as
- tough as an IL2, but, certainly wing flex is NOT the
- problem here.
-
-

Couple that with the guns in each wing being close together, not much flex between them so each group should stay tight to itself.


Neal

Hunter82
10-03-2003, 05:38 PM
I was having this conversation last night with a few friends on round dispersion on the P47...was funny I came across this post actually. We're (about 5 of us) in total agreement that the dispersion is too great even when convergence is altered the grouping does not seem to interact as it should.

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XyZspineZyX
10-03-2003, 07:16 PM
I'm starting to agree with the majority that there is something wrong with the .50cal guns. I find pretty much every other machine gun in the game, the ones that tend to appear in pairs or as a single gun seem to be more effective than a controlled combined burst from a six or eight gunned .50 cal fighter.

With virtually everything else I can get a kill with but it seems like unless you have the perfect shot, its unlike that you will do much of anything.

Its to the point where I fear a single Soviet or German machinegun than I do a P39, P40, or P47 on my tail with multiple guns.

Something is wrong with them...it may be a bug, it may be the damage model, it may be miniscule but they just don't seem to be like most of the other guns in its class for whatever reason.

http://freespace.volitionwatch.com/icefire/icefire_tempest.jpg
"Never in the field of human conflict was so much owed by so many to so few." - Winston Churchill

XyZspineZyX
10-03-2003, 07:29 PM
I find that occasional snap shots will take wings and tails off. And, although not quickly, I can even blast tails and wings off of 190s in the QMB.

My feeling is that the damage is probably fine. It's the dispersion on the 47 that is the problem. The P-40 seems to hit harder for example. Seems to have less dispersion. Though I admit it has been since 1.0 since I spent any time with the P-40.

XyZspineZyX
10-03-2003, 08:08 PM
They key to the P-47 now isn't to kill your victim, but to severly maim him/her.

We all know that when a Fw-190 has been hit hard enough, it becomes unflyable, and the same goes for the Bf-109.

There may be something wrong here, but in this game I've learned to improvise and adapt.

http://www.mechmodels.com/images/klv_ubisig1a.jpg


Oh yeah, I'm a P-63 whiner too! /i/smilies/16x16_smiley-very-happy.gif

XyZspineZyX
10-04-2003, 02:03 AM
I have felt the dispersion is too great for P-40 and P-47 for a long time. And I believe this is the reason behind the feeling that the .50's are underpowered. The .50's do seem a SLIGHT bit underpowered but they are so easy to hit with so any increase in hitting power might make them too strong. The fact that the 190 has a simplified DM certainly adds to this, as the ,50's are really effective against VVS planes for example. In my opinion there should be less dispersal, making it harder to hit with these guns but giving them more punch. Just my thoughts.

<center>
http://www.brooksart.com/Icewarriors.jpg

"Ice Warriors", by Nicolas Trudgian.

XyZspineZyX
10-04-2003, 02:16 AM
My opinion:

The P-40s guns don't appear disperse more or less than any other browning .50 cal modelled in the game. It's that the airframe seems to shake less under the force of the guns. They still move in the vertical as much as any other browning .50.

The P-39's nose .50s also have a quite ridiculous spread. Take a look at the Q1 and Q10 from the maximum zoom gunsite view and you'll see the tracers go out at around 5-10 degrees declination.

It's worth taking a look from an external view at maximum zoom at both the P-47 and P-40 looking down at the aircraft from above and watch the aircraft under the force of firing.

Anyhow, second what people have said so far, but it might be worth making some screenshots of a trimmed/stabilised aircraft firing and note the angles of the tracers to really nail the issue down.

http://home.iprimus.com.au/djgwen/fb/worker_parasite.jpg

Need help with NewView? Read this thread. (http://forums.ubi.com/messages/message_view-topic.asp?name=us_il2sturmovik_gd&id=yzbcj)

XyZspineZyX
10-04-2003, 02:52 AM
We need a couple of those gents who run around, to come out to the tarmac and lift the tail up, so we can set the in/out up/down convergence ! /i/smilies/16x16_smiley-happy.gif

I set my inboard and outboard guns all to 400 meters.

I have not had enough to make a good opinion on the 50 cal topic, in 1.1

However, in 1.0 and the first patch, the P47 could shoot down 5-7 Me109s and 4-6 FW 190s, in QMB.

The vital key to this is NOT shoot straight 6, but with at least 10-15 degree or more offset hi/low, or left right...

Deflection shots are most effective.

I often use just 4 guns, and sometimes come in with all 8 for the kill, or especially when I have a sure gunnery solution, even out to 500m.
Again, these comments prior to the latest patch. With the latest patch it is no problem to go online and come back with 2 or 3 kills vs various types.

My 2 cents.


" The first time I ever saw a jet, I shot it down ": General Chuck Yeager, USAF, describing his first confrontation with a Me262 - - -
" Aggressiveness was a fundamental to success in air-to-air combat and if you ever caught a fighter pilot in a defensive mood you had him licked before you started shooting ": Captain David McCampbell, USN, leading U.S. Navy ace in W.W.II.

XyZspineZyX
10-04-2003, 05:25 AM
Did some testing...there is definately something wrong still with the guns but here's some of the planes I tested against using D10 with convergence set to 280 meters and extra ammo.

LaaG 1941 - falls apart from concentrated burst
MiG 1940 - totaly disintegrated
IL-2T - wing blew off after 2 seconds of concentrated fire
FW-190 - six seconds of fire, followed by wing snapping off
P-47D10 - first target exploded after 1-2 seconds, second target's engine failed after the first burst
Yak-7 - wings heavily hit, fuel leak on both wings, engine failed after 2 second burst

Its odd that I never get some of this stuff online...plus its usually against the FW's.

Conclusion:

- FW 190 DM seems to have problems. If its simplified, its in need of it being made more complex.

- .50 cals can do massive damage but in some situations seems like the guns do absolutely nothing at all despite the ranges being similar

- dispersal pattern is huge in some cases while falling in a concentrated area in others

- known bug with tracers not being seen at distance, I used the Del key to zoom my view so I could see the tracers which made leading the target easier

- from what it seems, watching slow motion playback, in some cases multiple strikes are made while in other cases the dispersion...even at extremely close range is so extreme that the target gets few hits at all

I think we've got something discovered here...the bullets seem to do the damage when they hit but because we cannot see the dispersion without looking closely (because the tracers are almost invisible) it seems frusterating that we cannot score good kills.

http://freespace.volitionwatch.com/icefire/icefire_tempest.jpg
"Never in the field of human conflict was so much owed by so many to so few." - Winston Churchill

XyZspineZyX
10-04-2003, 06:49 AM
I believe the 190's and Lagg's simplified DM's are known and will be fixed.

<center>
http://www.brooksart.com/Icewarriors.jpg

"Ice Warriors", by Nicolas Trudgian.

XyZspineZyX
10-04-2003, 07:30 AM
RAF74BuzzsawXO:

What were the muzzle velocities of the guns in question? All is not a matter of mass. The German guns quite often were of higher velocity. I don't know if that is the case here. But without the velocity information, total energy of load cannot be calculated.




Luckyboy = senior hydraulic landing gear designer for the P-11

Message Edited on 10/04/0301:38AM by LuckyBoy1

XyZspineZyX
10-04-2003, 09:48 AM
BlitzPig_DDT wrote:
- Thanks Milo, I was just gonna dig for a pic like
- that. I can't believe everyone jumps on this wing
- flex crap. The P-47 was heavier than the freakin IL2
- for god's sake.

The Boeing 777 is heavier than both and the wings
flex like a seagull flapping its wings on the 777!
The size of the plane doesn't necessarily mean that
the wings necessarily flex less. The amount of
recoil force relative to the overall stiffness of the
wing might be less, but there may be a dispersion
fudge factor modelled to account for flex under maneouver
(which I doubt is modelled in fine detail - it certainly
isn't visually). The relative stiffness of the wings
relative to maneouver forces might be lower for the P47
than the P40, for example. I don't know for sure, since
I can't convert the diagrams into figures for stiffness.
My father-in-law is a structural engineer, though, with
a keen interest in WW2 aviation, so I am going to ask
him to take a look.

The P40 was an old design (a reengined P36, essentially)
and the P47 was a new design with thinner wings, so the
relative stiffness to weight (and hence maneouver
forces) might be higher for the P40 than P47. Wing flex
(as well as gun grouping) was one of the things that
made the 8 gun Spitfires less accurate than the 8 gun
Hurricanes, and was also an issue for the thin-winged
Tempest when compared to the thick-winged Typhoon (in
this case both aircraft being very similar apart from
the wing).

If you look at Ogre's site, you see that wing flex is
one of the factors he accounts for in his dispersion
diagrams (being one of the factors that leads to
increased dispersion for 20mm wing mounted guns due to
higher wing flex under higher recoil of fewer
discrete firing events for 20mm cannon).

Finding figures for a P40's wing thickness is another
matter... I don't have any books that reference it, so
I looked on the web and I am currently downloading someone's PhD thesis on wing flex..

XyZspineZyX
10-04-2003, 05:47 PM
Once again, Aaron is after me in near Clint-Ruin style. /i/smilies/16x16_smiley-indifferent.gif

I don't know what your problem has been lately, but I suggest looking into it. It would probably do you a lot of good.

777s a huge planes. Make a P-47 look small. The IL2 was larger than the P-47. So that means the P-47, with its' all metal heavily re-enforced structure was heavier while also being smaller. The weight came from all that structural integrity, not from sheer size (like is the case of the 777).

See?

Also, see Neals point about the amount of space between the weapons, just how much flexing are you going to try to claim is happening there?

XyZspineZyX
10-04-2003, 06:15 PM
BlitzPig_DDT wrote:
- Once again, Aaron is after me in near Clint-Ruin
- style.

Nope. Just after the truth. I have only a dim idea
of who this clint person is. I am using, as
my null hypothesis, that the game is correctly modelled.
If it is shown not to be (I was among those calling
for the P47 roll rate to be corrected, and posted
figures from a host of other sims as comparasion)
then I'll call for it to be changed too. But I don't
use the idea that 1C is somehow biased against US
aircraft as my null hypothesis. But I also think it
is not safe to assume that since two planes share
the same gun type, the performance of the guns in
location are necessarily identical, and I can see
that there are possible mechanisms to explain differences,
and I think that they are worth exploring.

- 777s a huge planes. Make a P-47 look small. The IL2
- was larger than the P-47. So that means the P-47,
- with its' all metal heavily re-enforced structure
- was heavier while also being smaller. The weight
- came from all that structural integrity, not from
- sheer size (like is the case of the 777).

Yes, I understand this. My point was that a plane
being large or relatively large (the P47 is a
relatively large single seat fighter) does not
mean that the wings are necessarily stiff. Note
that there is a difference between being strong
and stiff. The wings can be strong and flexible
at the same time, much as the wings of a 777
are immensely strong, but also relatively flexible.

- Also, see Neals point about the amount of space
- between the weapons, just how much flexing are you
- going to try to claim is happening there?

I am not suggesting that there is any flexing between
the guns. That would be absurd. I am speculating
(and I am speculating, I am not stating this as a
fact, so don't get all paranoid) on whether the wings
_as a whole_ may flex significantly in a P47. This would
mean that the two groups of shots would be thrown
in different directions. In real life this would tend
to lead to two relatively tightly grouped sets of
bullets (from each of the 4 guns). In terms of
the total dispersion between the 8 guns, this might
mean a high dispersion, in that the two otherwise
tightly grouped 4 gun sections would be widely dispersed
from each other. The flex would be dependent on
maneouver stresses.

I have no figures for the wing flex of the P47. I know
have a PhD thesis containing all the equations that
would govern wing flex in non-combat situations, but
I have no way of filling in the parameters for the P47
and P40 (which would be the two most interesting aircraft
to look at) so until we find some definitive information
either way, it is speculation on my part.

Getting back to the game, there is more testing
that can be done to see if there is an issue with
dispersion modelling from .50s as a whole. The P40
tends to indicate that the base .50 dispersion is
probably reasonable. What we don't know is if there
is any form of modelling of wing flex. The chances
are that if there is any accounting for wing flex
it isn't being done in detail - e.g. it might be
that wing flex is modelled by simply applying additional
dispersion to each gun individually, rather than
the two groups of 4 guns. It would be easier to
code that way, if not as realistic.

Now, it is also possible that it is a bug in the game,
even if the P47 had a greater wing flex, and even if
the simplifications made (as suggested above) might
be moderately reasonable, as it might be possible that
the wing flex might be overmodelled at low maneouver
Gs. The suggestion that the dispersion is high even
when the P47 is at rest might suggest that. Maybe
further testing can reveal it.

Basically, in conclusion, we might have an attempt
to model a real life phenomenum. We may have a buggy
attempt to do so, or the phenomenum might not exist
at all, and it be a bug of that sort.

What would be very nice is for 1C to comment on if
there is any modelling of wing flex. Given the comments
after Oleg posted in the 190 thread I can see why
1C don't bother, though.

However, I am agnositic about whether the P47 is correctly
modelled with respect to dispersion until it is proved
either way, so maybe I am just acting as a devil's
advocate to a certain extent.

XyZspineZyX
10-04-2003, 06:44 PM
Dispersion on the P-47 is all fine. Come on, someone really excepts that simulatniously firing 8 HMGs will not rock the plane heavily, throwing off aim ? LOL.


No, the problem we have is that some crybabies can`t aim at all, and they are crying, crying crying to Oleg to intall some kinda Death Star laser on the P-47, so they can do what they usually do : fire from 6-700m away, just spraying the area madly, not aiming because "fifties are so powerful", instead of getting close and fire only when there`s good opportunty to hit.

But as long as we have these noobs onboard, they will cry to the heavens to make up for their impotent aiming skills.

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
10-04-2003, 07:12 PM
Vo101_Isegrim wrote:
- No, the problem we have is that some crybabies can`t
- aim at all, and they are crying, crying crying to
- Oleg to intall some kinda Death Star laser on the
- P-47, so they can do what they usually do : fire
- from 6-700m away, just spraying the area madly, not
- aiming because "fifties are so powerful", instead of
- getting close and fire only when there`s good
- opportunty to hit.
-
- But as long as we have these noobs onboard, they
- will cry to the heavens to make up for their
- impotent aiming skills.

That's just not true. Don't know why you post such a rubbish.

XyZspineZyX
10-05-2003, 12:02 AM
Vo101_Isegrim wrote:
-
-
- Dispersion on the P-47 is all fine. Come on, someone
- really excepts that simulatniously firing 8 HMGs
- will not rock the plane heavily, throwing off aim ?
- LOL.

How is dispersion from the FW190-A8? A lighter plane than the P-47 that throws such heavy firepower? With Mk103's in pods you shouldn't be able to hit anything if what you say now is true, LOL! But this is what we come to expect from you concerning non-German planes anyway.

- No, the problem we have is that some crybabies can`t
- aim at all, and they are crying, crying crying to
- Oleg

ROFL! YOU point and say abot crying! That is SO RICH!

I am sure that many 262 pilots caught by diving, speeding P-47's were very happy to know that those planes couldn't damage them enough to make a real difference. The wings were flexing and the bullets went everywhere after all, nothing to worry about.

- to intall some kinda Death Star laser on the
- P-47, so they can do what they usually do : fire
- from 6-700m away, just spraying the area madly, not
- aiming because "fifties are so powerful", instead of
- getting close and fire only when there`s good
- opportunty to hit.

You are saying something so far from what is discussed it is ridiculous, but if the dispersion is changed then SURELY those guns will become ultra-deadly at 700m! Funny though how making less dispersion isn't asking for more poserful bullets that would be neccessary for spraying madly to work... are you sure you're in the right discussion or maybe you are just in berserker attack mode, going after everything at once?

- But as long as we have these noobs onboard, they
- will cry to the heavens to make up for their
- impotent aiming skills.

All Hail Superior German Technology, the rest are junk! The Mighty and Supremely Talented Isegrim says so!

Enough with the BS of you and others!
================================================== =======

It does not matter that people watch the dispersion from overhead while the planes travel at sedate speed in straight and level flight... it becomes a matter of wing-flex in combat conditions to some and to Isegrim it is noobs who cannot aim. Those who cannot argue points as raised change the subject around to where they can argue and ignore what they cannot. No style from those quarters.

Funny but I think I remember backing dispersion being wrong from some 109's after seeing their tracers firing while PARKED. Do you, Isegrim, disagree? What is your position? Are those testers also bad shots? Will you accept the same about non-German planes? Do you bother reading this far after I write you are so biased it is sick? Hmmmmm?


Neal

XyZspineZyX
10-05-2003, 01:18 AM
It'd be great if we could focus on discussing possibilities and evidence rather than derailing the discussion onto the topic of exactly how much of a wanker Isegrim is.

And I think adding in some screenshots with angle lines traced from the gun ports to the tracers would actually be pretty useful.


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XyZspineZyX
10-05-2003, 03:41 AM
clint-ruin wrote:
- It'd be great if we could focus on discussing
- possibilities and evidence rather than derailing the
- discussion onto the topic of exactly how much of a
- wanker Isegrim is.
-

When he shows up, or his bud, in a thread the thread is heading for a derailment automatically.

XyZspineZyX
10-05-2003, 04:48 AM
Salute

In regards to wingflex:

The P-47, unlike either the 109, 190, P-39, or P-40 had TWO main spars in the wings, along with another THREE supporting spars.

All the other German aircraft I mention only had ONE main spar, and either 1 or two supporting spars.

No only did the P-47 have more structural members in the wing, they were constructed of heavier gauge metal.

Here are a number of diagrams which show the P-47's structure:

http://rwebs.net/avhistory/images/P47cutaw.jpg


http://rwebs.net/avhistory/images/wing.jpg


"Main members of the wing are the two main spars which support attachment of the wing to the fuselage and three auxiliary spars, one each supporting the aileron and flap and the other supporting the landing gear.

Main spars are constructed of E-shaped cap strips riveted to webs of varying thickness from a minimum of .032" for the outboard web of both spars to a maximum of .250" thickness for the inboard web of the forward main spar. Both main spars are reinforced at suitable intervals by extruded angles which also serve as anchors for frame installations.

Inboard ends of the main spars of each wing are fitted with a pair of wing hinges which are pinned to the mating fuselage hinges by split bushings; tapered bolts expand these bushings to a tight fit, thus securing positive attachment.

The aft auxiliary spars support the movable surfaces and are constructed of angle cap strips and webs of .072" to .025" thickness. The landing gear auxiliary spar, since it is subjected to landing loads, is of somewhat heavier construction-namely, .091" web and is reinforced similar to the main spars.

Flanged ribs of alclad 24-ST are secured between spars at the angle stiffeners. Ribs vary from .051 to .032 with the exception of the root chord rib and gun bay partitioning ribs; the root chord rib is .064" and the gun bay partitioning ribs of .064".

Nose and trailing edge ribs are flanged and are also of Alclad 24-ST."

The above details are from this site, which features an article on the P-47 by a Republic Engineer.

http://rwebs.net/avhistory/history/p-47.htm

Please Luftwaffe aficionados, provide similar drawings from the 109 and 190 which show anything CLOSE to that kind of structural strength.

You won't.


RAF74 Buzzsaw

XyZspineZyX
10-05-2003, 05:01 AM
Salute Isegrim

Since I am the author of this thread, I am assuming your comment about "...crybabies can't aim..." is directed at me.

What I am going to suggest then is that you will be given the opportunity to prove that I can't aim.

I challenge you to a online fight, one on one.

We will fly two matches, I would suggest on a Blitzpig server, since they are usually up.

Both matches start with planes on the ground.

First Match we both fly 109K4's with the same fuel load and weapons.

Second match we both fly P-47D10's with the same fuel load and ammo.

Matches to be recorded and the server log files provided to each player.

I think that should be sufficient to determine who can shoot and who can't.


RAF74 Buzzsaw



Message Edited on 10/05/0304:02AM by RAF74BuzzsawXO

XyZspineZyX
10-05-2003, 05:05 AM
That P-47 info has been posted on pg1. Maybe it will sink in this time for Isegrim.

Your duel, he won't show up,

http://www.ansi.okstate.edu/poultry/chickens/polish/BRDSILV2.jpg

XyZspineZyX
10-05-2003, 05:14 AM
Sadly, we haven't be "usually up" as of late, however, there are several of us capable of hosting and availble most any night. Post a message in our public forum ad we'd be happy to arrange for any requested times or settings.

BTW - LW guys, please post similar info for 109s or 190s regardless of Buzzsaws stupid taunts. I'd seriously love to see such detail for those planes. I'm just way too curious for my own good and have always loved both of those aircraft. /i/smilies/16x16_smiley-happy.gif

XyZspineZyX
10-05-2003, 06:22 AM
Off topic, but has anyone noticed that the MG/FF are far more deadly on the russian aircraft than the MG151/20?

Also, about the 50 cal... P-40 really is vastly more lethal than the P-47 in this way. But dispersion seems the same for all 50 cals, check out the P-39Q-10.

http://www.mechmodels.com/images/klv_ubisig1a.jpg


Oh yeah, I'm a P-63 whiner too! /i/smilies/16x16_smiley-very-happy.gif

XyZspineZyX
10-05-2003, 09:55 AM
Vo101_Isegrim wrote:
- Dispersion on the P-47 is all fine. Come on, someone
- really excepts that simulatniously firing 8 HMGs
- will not rock the plane heavily, throwing off aim ?
- LOL.

I don't really buy that as a source of the dispersion.
If you take the maximum weight of the P40E1, and divide
by 6 guns you get 688 kg/gun. If you do the same for
the unloaded weight of a P47D10 you get 600kg/gun. If
you added in the ammunition, then you'd likely be up
to the 688 kg/gun figure. I.e. the inertia per gun of
the most lightly loaded P47 possible is no worse than
the most heavily loaded P40 possible. Thus it can't
be related to the whole plane shaking that is the
factor.

All up weights are - P40E1 - 3133kg empty, 4131kg max,
giving wing loadings of 143 to 188 kg/m^2

For the P47C1 - 4812kg empty, 7900kg max, giving wing
loadings of 172 to 283 kg/m^2.

Thus the P47 wing structure is almost always going to
be bearing a heavier loaded per unit area, so a hand
waving assumption (since a detailed structural analysis
isn't going to be possible!) is that if the wings are
uniformly strong over all areas, and the wings were of
the same general construction, then the P47 wing would
be more subject to deformation under maneouver than that
of the P40.

I haven't been able to track down any information on
the P40 wing construction to see if the P40 has a stronger
wing in relation to its weight than the P47, or a weaker
one, or a weaker but stiffer one, etc.

Another plane to look at might be the P51, as that
is a modern plane for the 1940s with a thin wing, perhaps
closer to the P47 in this sense, than the venerable P40.
So maybe if wing flex is modelled, the P51 might have
high dispersion too. Then again, it might have some
simplifications for AI-only use.

Of course it is still entirely possible that the P47
gun dispersion in the game isn't an attempt to model
wing flex, and is just a plain old bug.

XyZspineZyX
10-05-2003, 10:11 AM
As has been mentioned, the dispersion of the tracers seems to affect all browning .50 cal rounds. Unless that is someone has documentation on the nose-flex of the P-39.



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XyZspineZyX
10-05-2003, 10:38 AM
RAF74BuzzsawXO wrote:
- The P-47, unlike either the 109, 190, P-39, or P-40
- had TWO main spars in the wings, along with another
- THREE supporting spars.
-
- All the other German aircraft I mention only had ONE
- main spar, and either 1 or two supporting spars.

This doesn't quite do the FW 190 justice. Even though the second spar didn't run the entire lenght, I wouldn't label it a "one spar" design. It much more a "one and a half spar" design, closer to two spar than to one spar.

XyZspineZyX
10-05-2003, 11:29 AM
Sadly, this thread is still merely about Buzzshaw usual rantings about how much easier should it be with a P-47. I guees he can`t hitting anything.

I am sorry if some of you guys still didn`t get, but you don`t get 8 fifities all the time; you get them only at convergence, if don`t count dispersion. And sorry, dispersion from guns in the wings will always be higher than centerline guns, as the latter act directly against the thrustline, and don`t create sideway twist forces. Yall have to live with that, too.

And sorry again, guns that rely only on kinetic energy, will loose their power quickly with distance, they have only about 75% of the KE at 300m, and about 40-50% at 700m you would like them to work. In other words, out of the Jugs 8 HMS, you have about effectively 2 at the ranges you use to fire at, taking into account everyting... and you wish them to be deadly, ripping things apart from a short burst? Sorry, not even cannons do that in FB.


So far there are NO actual data on the P-47s dispersion, only wishful comments from some, who want to shoot down planes from a kilometer away... even when real life aces (Gabriesky? ) used to fire from point blank ranges.

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
10-05-2003, 03:19 PM
Right, so ignoring the guy above (suggest all others do so as well) I played against some guys online last night.

I was flying the .50 cal almost invulernable FW-190 A9. The guy was a distance of between 0.20 and 0.35 during the fight as I was trying to get away from his P47D10 (if it were a D27 I'd pull back hard on the stick and watch him stall - seems odd eh?). Anyways, he must have had the extra ammo added to his plane as he was unleashing massive barrages of .50 cal shots. I was looking back over my plane at the guy...I even flew straight for some time. He was really close with a clear shot and me flying the level (I was interested to see what would happen). Even at extremely close ranges...only a few of the bullets were actually hitting me...the rest flying all over the place.

Its one thing to say that you just aren't close enough for the tactic of bullet dispersal to work, but when the guy is right ontop of me...with a solid shot and firing all guns in my direction for several seconds, you'd think my plane would be introuble.

I flew back to home base with a minor fuel leak and a chewed up rudder.

Now the FW has its problems...but it was interesting to see how few of the bullets were hitting me. In comparison, the guy in the Yak 3 with his machineguns blaring was able to hit me alot more than the P47 was.

So the question is: was the .50 cal dispersal pattern THAT much more than other MG's of the time?

http://freespace.volitionwatch.com/icefire/icefire_tempest.jpg
"Never in the field of human conflict was so much owed by so many to so few." - Winston Churchill

XyZspineZyX
10-05-2003, 05:07 PM
Aaron, the P-47 wasn't a "new" design. It evolved from the SEV-3XAR which was flying in 1934 (then it became the SEV-1XP, then the P-35, then the P-43....eventually becoming the P-47).

Furthermore, the reputation for being such a brutal and devestating killer, specifically due to having 8 guns, would not have occured with dispersion such as we have.

If the dispersion was really this bad with 8 guns, the gov't would have simply refused to buy them with more than 6, saved money, and put the remaining 2 to good use other places (on bombers, AAA batteries, other fighters, etc).

I know that gov't are seldom logical, but, America of the 40's was a hell of a lot better than America of today.

XyZspineZyX
10-05-2003, 05:34 PM
What I want to know is how did they figure out that the P-47 had such bad dispersal and some of the other planes didn't? Or was this pulled out of thin air?

:FI:SnoopBaron

http://www.endlager.net/fis/pix/banners/fis_banner_07.gif

XyZspineZyX
10-05-2003, 10:01 PM
Snoop_Baron wrote:
- What I want to know is how did they figure out that
- the P-47 had such bad dispersal and some of the
- other planes didn't? Or was this pulled out of thin
- air?
-
- :FI:SnoopBaron


Most likely the latter. Oh, for christ sake, 70% of these guys were crying the place all over about ,50 effectiveness on other even before FB came out ! On my part, I checked it for curiosity, with Arcade mode, and I found the spreading is no worser than on any other wing mounted aircradt.

Simple as that, the guys loosly spray the general area of the a/c in front of them at great distance, score 3-4 hits out of hundreds spent, don`t even realize it`s NOT THE GUNS FAULT just their own. Then they come here and cry.


Seriously, what the heck we have seen that would prove the guns on the P-47 have big or bigger dispersion ? Nothing at all. We saw a picture of P-47 guns (nice), plus a link to an internet site that say the P-47 has x amount more firepower than the 109 (+ usual stupid tirades of Buzzsaw).


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'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
10-06-2003, 06:00 AM
There might be a problem with yaw/pitch axis stability while shooting. The dispersion itself, is fine.

All of the planes suffer to a certain degree the effects of the guns firing - for instance, when firing the nose mounted guns on the Bf109s, the nose pitch down a bit very slightly.. about 1~2 degrees..?

Much the same, the P-47 suffers a 'shake' in the yaw axis while the 8 guns are firing. The fishy part is, the yaw tendency observed, seems to point out that the firing sequence on the 8 guns are not simultaneous, but in alternation. It seems to switch between more guns fired in the left wing than right, then more fired in the right than left. The result, is a shake in the yaw axis which tends to be really annoying.

Now, this isn't a problem when you have a good firing solution in the P-47 - where you prepare to fire and hold the stick really steady and cautious. However, it becomes a handful when you have to make adjustments to the aim, and particularly fatal when you attempt to adjust aim while firing.

Charactersitically the P-47s need to fire a long, tracking burst into the enemy to achieve good results. Also, due to its fighting style, typically the approach speed to the target, is very fast.

This often brings out a situation where a pilot starts shooting, then he sees the shake is causing the aim to drift a little bit off. Seeing that the drift isn't much, the pilot tries to compensate WHILE holding down the trigger, and it is at that moment the guns go wild.

So as it is, I could recommend that if one must change aim during shooting with the P-47, pull the finger off the trigger, adjust, and then fire again - no matter how small the difference seems to be. Never, ever change aim or compensate drift with stick, while pulling trigger.

...

Is that realistic? I have no idea. All I can present here is the observation.



-----------
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XyZspineZyX
10-06-2003, 06:02 AM
What we really need, is a P-38. /i/smilies/16x16_smiley-indifferent.gif

http://www.mechmodels.com/images/klv_ubisig1a.jpg


Oh yeah, I'm a P-63 whiner too! /i/smilies/16x16_smiley-very-happy.gif

XyZspineZyX
10-06-2003, 12:09 PM
BlitzPig_DDT wrote:
- Aaron, the P-47 wasn't a "new" design. It evolved
- from the SEV-3XAR which was flying in 1934 (then it
- became the SEV-1XP, then the P-35, then the
- P-43....eventually becoming the P-47).

The Spitfire evolved from the Supermarine aircraft
of the late 1920s..

The P-40 was initially just a P-36 with a new engine.
The P-36 prototype flew in 1935. So in the P-40 we
have a reengined plane that first flew in 1935. There
was rather more design work between the SEV-3XAR and
the P47 then the P-36 prototype and the P-40. The
heritage of the wing shape was certainly born in the
earlier Kartvelli designs, via the P-43, but the
P-47 design was more modern than the P-36.

What I don't have is any references on P40 wing
construction, any references to relative wing thickness,
or any statements on wing flex of the two planes.

- Furthermore, the reputation for being such a brutal
- and devestating killer, specifically due to having 8
- guns, would not have occured with dispersion such as
- we have.

Many things can lead to a reputation, and sometimes
a reputation can be bad despite the plane being good.
E.g. the received wisdom has been that the P-39 was
terrible, but some USAAF pilots loved it, and the USSR
said it was competitive. It could be that many things
contributed to the reputation of the P-47, so it is better
to try and use objective analysis. But we are lacking
details noted above on wing flex, etc.

- If the dispersion was really this bad with 8 guns,
- the gov't would have simply refused to buy them with
- more than 6,

You could also argue that if dispersion was bad then
they felt that 8 guns were required! Actually the P47B
(not cleared for combat) was, according to the pilot's
manual posted by one of the Brazillian players, cleared
for either 267 rpg with 8 guns, or 350 with 6 guns. So
some were only fitted with 6 guns. Likely this was
due to weight and performance issues, though.

I am open to persuasion in either direction, though.
I just have a null hypothesis to begin with.

I did try and find a way to test dispersion against
a fixed object when at rest in the game, but I haven't
found a good way to do this yet with a tail dragger.
Any hints on a good way to do this?

XyZspineZyX
10-06-2003, 12:17 PM
Vo101_Isegrim wrote:
- Most likely the latter. Oh, for christ sake, 70% of
- these guys were crying the place all over about ,50
- effectiveness on other even before FB came out !

I'm more of a 20mm cannon whiner, and I find that the
P40 seems to be more effective than the P47, at least
in terms of subjective impression. You can still chop
things apart pretty nicely with the P47 if you get
the combination of targeting and convergence right, but
it seems to be easier with the P-40.

It's hard to be scientific about the observed dispersion
without firing butts being modelled, but if you fire
at the ground, the P47 appears to have quite a lot of
dispersion modelled (I trust bullet strikes more than
the tracers).

The difficult thing is controlling for the other variables
that change between P47 and P40, of course, hence my
question about if there is anyone has set up the two planes
against a static target, as then the two planes can be
tested under 1G load, as a test of statuc dispersion.
(There might be different modelling under movement in FB,
of course).

XyZspineZyX
10-06-2003, 01:52 PM
Kweassa, I recorded an online track in Gemini's server this weekend. He put cliffs around the airfield and I took that opportunity to start recording, turn to face them and open up.

With all 8 at once, it spins to the right. Even with the brake on and rudder at neutral. With just one set, (trigger I think) it went right, and with the other, it went left. Something is definitely off here.


Aaron - come on dude. How would it be thought that 8 guns were needed to deal with dispersion when the vast majority of other US planes did just fine with only 6? You say you are neutral on this, but you are trying to counter too hard to really be neutral.

XyZspineZyX
10-06-2003, 05:13 PM
If each gun is modelled as to recoil and when they fire each one starts in sequence instead of all at once... and the sequence isn't left-right-left-right but right-right-left-left or worse 4x each then the more guns, the worse the yaw factor. Even moreso if there's another task or more done in between getting one or more guns started and the next. It's like hooking up sparkplug wires in sequence around the engine and expecting it to run right.


Neal

XyZspineZyX
10-06-2003, 06:07 PM
BlitzPig_DDT wrote:
- Aaron - come on dude. How would it be thought that 8
- guns were needed to deal with dispersion when the
- vast majority of other US planes did just fine with
- only 6?

That doesn't really constitute any sort of proof.
Anyway, I wasn't being particularly serious about
suggesting that the P-47 needed to have 8 guns
to deal with dispersion.

If you look at the history of the P-47 and other
aircraft, the USA seemed to be in a battle to up
gun its aircraft throughout WW2 (as most nations
also did) but for most of the fleet the limit
was 6. The P-47 could carry more, and so often did,
but sometimes (when weight was more of an issue
and extra performance or range was needed) it was
reduced to 6.

So basically the number of guns on other US
fighters doesn't necessarily mean that the installation
on the P-47 was less (or more) susceptible to
dispersion for whatever reason.

- You say you are neutral on this, but you are
- trying to counter too hard to really be neutral.

If you say so.

XyZspineZyX
10-06-2003, 06:11 PM
WWMaxGunz wrote:
- If each gun is modelled as to recoil and when they
- fire each one starts in sequence instead of all at
- once... and the sequence isn't left-right-left-right
- but right-right-left-left or worse 4x each then the
- more guns, the worse the yaw factor. Even moreso if
- there's another task or more done in between getting
- one or more guns started and the next. It's like
- hooking up sparkplug wires in sequence around the
- engine and expecting it to run right.

Interesting...

It does seem to be doing some extra yawing in there.

If you have a gyroscope spinning and try to press
it down, does it yaw to one side of the other? I
seem to remember it does. But then if it was a gyroscopic
effect (the guns effectively pressing the gyroscope
backwards due to recoil) you'd expect it to be consistent
depending on whichever trigger you use unless the
firing sequence is very out of step. But why would you
model an out-of-sequence firing?

If there is a gyroscopic effect then if we finally
get Spitfires, the early Spits and the XIV should yaw
in different directions.

XyZspineZyX
10-06-2003, 11:26 PM
If I was moving the gyro along the line of its axis I would expect no gyroscopic effects.


Neal

XyZspineZyX
10-07-2003, 10:35 AM
I also wonder, what about if the yaw movements from recoil happen when the pilot flies with the ball not centered... I presume this would add some sideslip to the flightpath.

BTW, try out to set Arcade-1 in conf.ini, and then take a P-47 and P-40 for a dive, aim for a tree on the ground, and try to hold the aim steady. Personally, I didnt found much difference, maybe its just the P-40s guns are closer to each other (ie. distance between the two cluster of guns in the 2 wings are smaller).


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XyZspineZyX
10-07-2003, 11:10 AM
WWMaxGunz wrote:
- If I was moving the gyro along the line of its axis
- I would expect no gyroscopic effects.

Good point. Not having a gyroscope any more I don't
have anything to test with :-)

XyZspineZyX
10-07-2003, 11:25 AM
Shockingly enough: Oleg has yet to reply... wonder why that is.

XyZspineZyX
10-07-2003, 01:16 PM
"I also wonder, what about if the yaw movements from recoil happen when the pilot flies with the ball not centered... I presume this would add some sideslip to the flightpath."

That reminds me... The default state of the P-47 will not offer a totally level flight in terms of yaw - the P-47 in FB needs average 15~20 clicks of rudder trim to correct the side slip.

The side slip cuts off about 2~3km/h from the maximum level speed - at least that's what I noticed from my previous speed tests with the P-47. But then again, there's always a little amount of side slip in every plane, but none of the others have such a large yaw instability during firing.

My 2 cents worth of observation.



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