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Legioneod

P-47 Flight Model Discussion

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On 5/4/2019 at 10:43 AM, Bremspropeller said:

 

I think the structure-issue is a major drawback on the P-47. The ailerons coming off just isn't right.

The key might be the high-speed aerodynamics modelling, which hopefully will be improved with the 262.

 

Got any specifics WRT elevator authority?

There is NACA paper on the P-47 that has lbs/g but I can't find it at the moment IIRC it is something like 3-8lbs/g depending on the CoG

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21 hours ago, Bremspropeller said:

My point WRT aileron flutter is that the P-47 actually had a quoted aileron-reversal speed, which means this speed is attainable from a structural and aeroelastical standpoint.

 

It's possible to calculate that speed. I know NACA did that for the P-47. I don't know if they also tested it.

 

Additionally, aileron reversal speed is mostly dependent on IAS, while flutter is mostly dependent on TAS or even Mach. So it is entirely possible for any aircraft to be limited by dynamic issues (flutter, compressibility) at high altitude and static issues (structural strength, aileron reversal) at low altitudes.

 

NACA tested the P-47 with several different ailerons, and found solutions that were superior to the serial production version of the time. I'd be surprised if none of the NACA findings were ever incorprated into the P-47 design, so I'd recommend to be careful when using data from other submodels.

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It's quite normal to be IAS-limited at high altitude (meaning: Vne decreases with altitude) in GA aircraft.
 

I have seen aileron reversal speeds mentoned, while aileron-flutter isn't.

I haven't seen any evidence of flutter issues with the P-47 whatsoever.

The only way to induce flutter should be the usual suspects, like banged-out bushings, too much control-play and wrong counterbalance-masses.

 

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Posted (edited)
5 hours ago, Bremspropeller said:

It's quite normal to be IAS-limited at high altitude (meaning: Vne decreases with altitude) in GA aircraft.
 

I have seen aileron reversal speeds mentoned, while aileron-flutter isn't.

I haven't seen any evidence of flutter issues with the P-47 whatsoever.

The only way to induce flutter should be the usual suspects, like banged-out bushings, too much control-play and wrong counterbalance-masses.

 

 

I've never read of flutter occurring in the P-47 but like you said, aileron reversal most certainly did. For those interested aileron reversal was usually experienced around 540 mph IAS from what I've read.

 

EDIT:

Aileron reversal isnt modeled in-game so it's kind of irrelevant to the discussion imo.

Either way the speeds at which the P-47 breaks up is incorrect, realistically it shouldn't occur on the P-47 at all (in a normal dive), it's maximum speed possible in a dive is Mach 0.83 (around 630 mph or so) iirc, the P-47 could dive at these speeds without breaking up.

Edited by Legioneod
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55 minutes ago, MeoW.Scharfi said:

 

 

I thought only Pe-2s could accomplish such feats! Has my whole life been a lie????

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On 5/5/2019 at 10:19 AM, Bremspropeller said:

My point WRT aileron flutter is that the P-47 actually had a quoted aileron-reversal speed, which means this speed is attainable from a structural and aeroelastical standpoint.

 

 

 

It does not mean that. Reversal speed is just a calculated number and it doesn't mean the speed is attainable from the structural standpoint. Aileron reversal speed is almost all cases well above the Vne of the aircraft, often in the vicinity of Mach 1.

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On 5/24/2019 at 3:32 PM, RedKestrel said:

I thought only Pe-2s could accomplish such feats! Has my whole life been a lie????

The gunners in il2 need a general debuff. Same with the flak. The AAA and tail gunners in il2 may as well be radar guided. The P-47 damage from that 7.62 was also absurd, but the fact that it even got those hits was nuts. 

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On 5/28/2019 at 3:09 AM, VO101Kurfurst said:

 

It does not mean that. Reversal speed is just a calculated number and it doesn't mean the speed is attainable from the structural standpoint. Aileron reversal speed is almost all cases well above the Vne of the aircraft, often in the vicinity of Mach 1.

 

Depending on altitude and other factors the reversal speed of the P-47 was around 540 mph in most cases, this is well below the structural limits of the aircraft.

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Posted (edited)

The model in the above mentioned NACA report ( D-30 ) is not the one we have in-game...( D-28 ) ?

 

Our model, for instance, does not have dorsal fin. This should actually make it even less stable directionally ?

 

Anyway, it's interesting to read about the pitch stability in that report. Comparing to the model in-game it appears it has not much in common ? I haven't been able to quite reproduce the reported instability.

 

Also mentioned in that report, having blown-flaps, they should retract at higher dynamic pressure values - not the case in our D-30 model ? I've tried to reproduce it flying in full landing conf, as well as other intermediate settings, and no partial flap deployment resulted.

 

Edited by jcomm-il2

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Is the engine more powerful now with update 3.101 or am I just imagining it? 

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18 hours ago, Jmo said:

Is the engine more powerful now with update 3.101 or am I just imagining it? 

Yesterday on Combat box at alt of 1500m I couldnt catch P47 in straight line in 190 A8. I was rather surprised. I have no idea if anything changed though.

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Posted (edited)
1 hour ago, CSAF-D3adCZE said:

Yesterday on Combat box at alt of 1500m I couldnt catch P47 in straight line in 190 A8. I was rather surprised. I have no idea if anything changed though.

even before last patch P-47 on full boost is faster then 190a8 on full power at 1500m, it was faster then a8 on any alt exept sea level, so if he was using his 5min of boost then its normal you could not catch him in A8

 

EDIT:

i check speeds on P-47 in new patch and its exactly the same as before, also i dont see any changes in dive, max dive and losing alerons, turn and super flaps behavior, climb or engine timers... so it looks nothing changed for P-47 in latest patch

Edited by 77.CountZero
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2 minutes ago, 77.CountZero said:

even before last patch P-47 on full boost is faster then 190a8 on full power at 1500m, it was faster then a8 on any alt exept sea level, so if he was using his 5min of boost then its normal you could not catch him in A8

Thanks mate. 

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3 hours ago, 77.CountZero said:

even before last patch P-47 on full boost is faster then 190a8 on full power at 1500m, it was faster then a8 on any alt exept sea level, so if he was using his 5min of boost then its normal you could not catch him in A8

 

EDIT:

i check speeds on P-47 in new patch and its exactly the same as before, also i dont see any changes in dive, max dive and losing alerons, turn and super flaps behavior, climb or engine timers... so it looks nothing changed for P-47 in latest patch

Dammit would hope it get some love..  maybe someday it will be a p-47

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On 6/12/2019 at 1:28 PM, 77.CountZero said:

even before last patch P-47 on full boost is faster then 190a8 on full power at 1500m, it was faster then a8 on any alt exept sea level, so if he was using his 5min of boost then its normal you could not catch him in A8

 

How do you know that? Do you have a chart?

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On 6/12/2019 at 7:21 PM, MercCrom175 said:

http://vintageaviationecho.com/p-47-thunderbolt-nellie/. Please read great write up.  This bird is the best bird in this game please take the time to get her right

I don't see anything in that write-up that you can't do in the P-47 in the sim.

People asking for fixes need to find actual, solid data to back up the fixes, not the impressions of individual pilots. Subjective experiences are extremely difficult to translate into a flight model -its poetry vs. math. As we've seen here with the dive data we delved into extensively, pilot descriptions have to be taken within the context of the pilot mindset at the time and the situations they experienced. Actual tests show the dive advantage was more marginal quantitatively than the qualitative sources (i.e. pilot accounts) would suggest. 

Having flown the P-47 in sim a bit, it handles pretty much like I would expect. It handles well at medium-high speeds and has a surprisingly good instantaneous turn, but a sustained turn bleeds your energy very quickly (as stated in the above arcticle, sharp movements bleed airspeed very quickly) and when it gets slow its a dog and hard to regain speed (once again, also just like its mentioned in the article above). It appears to require a lot of rudder-work but that is consistent with pilot accounts that I've read that indicate the rudder is as essential as the ailerons. It taxis, takes off and lands like a dream but needs a long runway, which is straight from the manuals and pilot accounts. Its roll rate is excellent, as expected. It dives well - its more held back by people's inflated expectations than reality in this regard. 

The main issues with the P-47 modeling right now appear to be 'global' issues with how certain things are modeled: most planes lose control surfaces or parts of the aircraft when they exceed dive limits, even when that would not be the case in reality (in reality, many planes would likely just become unrecoverable and dive into the ground, without losing bits). Compressibility is modeled but may be simpler than it would be in real life. The flaps of all aircraft appear to be too effective at producing lift in turns or climbs, but its more noticeable on aircraft with poor low-speed turn performance like the P-47. The way engines are modeled right now enforce strict time limits where the manuals stipulate them, so the modeling favors aircraft with more forgiving engine operation manuals. 

People who are both on the Russian and English language forums report that there are many things in the works regarding modeling changes. I haven't been able to read the posts myself but there are indications that detonation may be modeled (which may entail an overhaul of how the engines work), pilot fatigue may come into play, among many other things.

TL;DR - saying the P-47 'needs some love' is all well and good, but it doesn't get us anywhere. Solid data, reports, and most critically the understanding of how that data was arrived at and the context of the testing, is what will change things. Otherwise we're just constantly re-litigating every factoid and pilot account thrown out there and giving the devs nothing solid to work with. 

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On 5/30/2019 at 12:28 AM, Legioneod said:

 

Depending on altitude and other factors the reversal speed of the P-47 was around 540 mph in most cases, this is well below the structural limits of the aircraft.

 

IIRC more like in the range of 800, but I would have to check NACA docs. Even the Spit was in the 550-600 range.

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Posted (edited)
10 hours ago, VO101Kurfurst said:

 

IIRC more like in the range of 800, but I would have to check NACA docs. Even the Spit was in the 550-600 range.

800 what? P-47 could never reach those speeds. Aileron reversal in the P-47 was around 540 mph IAS from first hand accounts and reports I've read. Structural limits of the P-47 were well beyond this and truly the limits aren't known for certain since no one ever reached them and lived to tell about it.

 

At the dive speed attainable in game the P-47 should never lose any surfaces in a dive unless damaged or excessive Gs. In a normal dive it shouldn't lose surfaces even up to it's maximum dive limit (around Mach 0.83 or around 630 mph).

 

Currently the P-47 loses surfaces between 540-580 mph IAS iirc, this should not happen in a (normal) dive.

Edited by Legioneod

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The Jug should reach terminal velocity well before parts start flying off.

Maybe Yaks and Laags lose ailerons in a dive, I cant' say...but not the Jug.

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That and a p47 never had a wing shot off in any recorded combat sorties...

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35 minutes ago, MercCrom175 said:

That and a p47 never had a wing shot off in any recorded combat sorties...

 

That seems a rather emphatic claim. Source please....

 

The P-47 was tough, no doubt, but given the losses sustained to e.g. high-calibre flak, that none ever lost a wing seems unlikely. More plausible that no loss of a wing was ever recorded, maybe, but that may be down to the records being incomplete.

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25 minutes ago, AndyJWest said:

 

That seems a rather emphatic claim. Source please....

 

The P-47 was tough, no doubt, but given the losses sustained to e.g. high-calibre flak, that none ever lost a wing seems unlikely. More plausible that no loss of a wing was ever recorded, maybe, but that may be down to the records being incomplete.

 
If you get a direct hit from an 88mm flak shell, you may not technically lose your wings if the entire plane just blows up.

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...maybe, and I stress the word "maybe" not due to fire from an enemy aircraft, but given the destructive power of the German 30mm I'd have to wonder about that given what I've seen them do to B-17 wings.

 

In any case, the only way they come off in a dive is hitting the deck portion of said dive.

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The damage model of the whole plane needs reworked. It's like flying a glass bathtub.

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What is an optimal diving angle of p-47? (With this angle you will reach greatest distance in shortest time, the best angle to run away or pursue someone)

 

Different planes have different angle, as it is the optimal way to transfer your engine power and potential energy (altitude) in to speed. I think this is what some pilots meant when talking about "great diver". It can maintain high speed at most shallowest angles and this run away faster or pursue someone better. 

 

 

 

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Posted (edited)
7 hours ago, JgonRedcorn said:

The damage model of the whole plane needs reworked. It's like flying a glass bathtub.

 

If the P-38 is released more able to take a solid hit than the P-47, I'll be severely disappointed.  As it is, I rarely touch the 47 as it's too fragile - and never in multiplayer.

 

4 hours ago, CptSiddy said:

What is an optimal diving angle of p-47? (With this angle you will reach greatest distance in shortest time, the best angle to run away or pursue someone)

 

Different planes have different angle, as it is the optimal way to transfer your engine power and potential energy (altitude) in to speed. I think this is what some pilots meant when talking about "great diver". It can maintain high speed at most shallowest angles and this run away faster or pursue someone better. 

 

 

 

 

I was in Berloga flying a 262.  I had a 47 on my tail and I dove straight at about a 40 degree angle.  We were both equally fast at the beginning of the dive at around 650kph.  I found that it certainly was not easy or fast to pull away from the 47 even when approaching 900kph (on the 262 speedometer that's TAS not IAS) and the throttle just below emergency power.  We began the dive around 6-7km altitude.   

Edited by =AVG77=Mobile_BBQ
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On 6/18/2019 at 4:19 PM, MercCrom175 said:

That and a p47 never had a wing shot off in any recorded combat sorties...

 

It might just be that if your plane's wing falls off it's unlikely you're going to be writing about it back at base any time soon

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Posted (edited)

I didn't had time to follow this discussion. 

 

On that website it seems there is a lot of interesting things to find: http://www.wwiiaircraftperformance.org/p-47/p-47.html

But as it's one of the first google results, I guess it's already been seen. 

 

I took a quick overview, it seems that all maximum speeds achieved with those tests are higher than what we have in game. 

Didn't see something about engine time limit with water injection, but I've heard it should be more than 5min... Any reports about that?

Edited by F/JG300_Faucon

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Posted (edited)
12 hours ago, F/JG300_Faucon said:

I didn't had time to follow this discussion. 

 

On that website it seems there is a lot of interesting things to find: http://www.wwiiaircraftperformance.org/p-47/p-47.html

But as it's one of the first google results, I guess it's already been seen. 

 

I took a quick overview, it seems that all maximum speeds achieved with those tests are higher than what we have in game. 

Didn't see something about engine time limit with water injection, but I've heard it should be more than 5min... Any reports about that?

they used this data for it:

 

and when you run test in game on latest patch on settings he say: 

at 24500ft i get 293mph ias (61MP 2700rpm )= 435mph tas , that doc say 437mph

at 15000ft i get 319mph ias (64MP 2700rpm )= 407mph tas , that doc say 404mph

at   5000ft i get 337mph ias (64MP 2700rpm )= 371mph tas , that doc say 370mph

so in game P-47 level speeds are exactly as doc they modeled it by.

 

when i check your link and compare with tests in game, on this charts from your link:
65MP 2700rpm chart is closes to what we have in game
p47d-44-1-level.jpg
orange line
p-47-level.jpg
in game level speeds at 5000ft (slightly faster in game), 15000ft, 24500ft, and even 32800ft (47MP-2700rpm= 237mph ias = 409mph tas ) and 36000ft (42MP-2700=210mph ias = 386mph tas) are very close to what that charts show for P-47D 42-26167 ( P-47D-22-RE ) at 65MP-2700rpm settings from your link.

exept in game P-47D-28 at 65MP-2700 does 352mph on sea level insted that P-47D-22s 340mph at 65MP 2700rpm like on that charts

 

5min limit is in manual, also 15min for military (combat) is in manual, so nothing to get wrong there, but why it takes 10min to recharg 5min of emergancy and 30min to recharg 15min of combat when on other airplanes (example 109G14, 109K4 10min emergancy recovers in 10min, 190D9 10min emergancy recovers in 15min, 262 15min emergancy recovers in 20min and so on ) its not that long, and also why when you use 5min of emergancy you lose 5 min of combat when on other airplanes (for example 109G14, 109K4, 190D9, 262 and so on ) combat timer dont get used like on P-47 and you have full combat time ready to be used after max power timer run out, is higly questionable, as that numbers are not taken from any manuals and should be working same for all airplanes then.

 

Edited by 77.CountZero
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IRL there is no 100% safe setting as a continuous will have some failures from time to time. Yet, Yaks, LaGG and the La-5F are completely unlimited in the game. That's pretty (stalinium level) funny when looking at Soviets manufacturing standards especially early in the war. Even funnier is how much Soviets begged for more LL but in the game the stuff (P-40/P-39) is just bad. That's not consistent; were they fools including Pokryshkin?!

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Posted (edited)
16 hours ago, F/JG300_Faucon said:

I didn't had time to follow this discussion. 

 

On that website it seems there is a lot of interesting things to find: http://www.wwiiaircraftperformance.org/p-47/p-47.html

But as it's one of the first google results, I guess it's already been seen. 

 

I took a quick overview, it seems that all maximum speeds achieved with those tests are higher than what we have in game. 

Didn't see something about engine time limit with water injection, but I've heard it should be more than 5min... Any reports about that?

 

Speed wise the P-47 in game is pretty close to reality (level speed that is) at the power setting we get in-game. I've been away from Il2 for a while but I plan on updating this thread soon.

 

WEP timers on the P-47 do come from the manual but they are wrong in the fact that the engine wouldn't blow just because you went over 5min. The P-47 has 15min of water for WEP use yet in-game you really never use it due to engine failure.

 

Read my second post in this thread. I go over the engine limits and why I think they should be changed.

Edited by Legioneod

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I feel as though I remember the devs explaining it before but can anyone tell me why the P-47's MP starts increasing below 3000ft instead of staying constant?

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Posted (edited)
12 hours ago, Legioneod said:

WEP timers on the P-47 do come from the manual but they are wrong in the fact that the engine wouldn't blow just because you went over 5min. The P-47 has 15min of water for WEP use yet in-game you really never use it due to engine failure.

 

The manual advises to hoard the supply of water. However, once needed it instructs to not hesitate. Makes sense.

The in game trick to get 15m of ADI is to use it on the combat mode at -6" than normally. It's wrong; nothing like this was done IRL nor was necessary. The water was for the WEP, only.

And yes - (in)famous manuals don't tell what happens if you exceed stated time intervals except a suggestion that your mechanic may work overnight, again. (by ruining the TBO)

Edited by Ehret
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2 hours ago, =362nd_FS=RoflSeal said:

I feel as though I remember the devs explaining it before but can anyone tell me why the P-47's MP starts increasing below 3000ft instead of staying constant?

The supercharger on the engine only produces full power up to 3,000 ft. after that you need the Turbosupercharger to get full power. Is that what you meant?

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21 hours ago, =362nd_FS=RoflSeal said:

I feel as though I remember the devs explaining it before but can anyone tell me why the P-47's MP starts increasing below 3000ft instead of staying constant?

 

It gets a boost for takeoff power supposedly. It also drains your timers faster.

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