P-47: bad at boom and zoom?

[II./SG.1-MarkWilhelmsson]

1 hour ago, Legioneod said:

DCS worked with real P-47 pilots as well, so who do we believe? I'm not saying one is better than the other but just because one pilot says it's good really doesnt mean anything. Same could be said for DCS.

 

Yea but I mean to his credit above others, this guy didn't just fly one, he OWNED one. Hahaha

 

Are we about to cross that line where we say that the word of a real life P47 pilot who has tried the IL2 version isn't good enough? This forum may just be a clown world after all hahaha

Edited June 9, 2020 by II./SG.1-MarkWilhelmsson

[Legioneod]

7 minutes ago, II./SG.1-MarkWilhelmsson said:

 

Yea but I mean to his credit above others, this guy didn't just fly one, he OWNED one. Hahaha

 

Are we about to cross that line where we say that the word of a real life P47 pilot who has tried the IL2 version isn't good enough? This forum may just be a clown world after all hahaha

Owning something doesn't necessarily give you're opinion more weight than someone else. Time actually spent in the aircraft is what makes the difference. Plenty of people own boats but you can find lots of videos of people who don't know how to use them.

[LColony_Kong]

So as many people have pointed out already, alot of this has to do with the fact that in multiplayer you are only facing the pinnacle of German piston fighters but not in a corresponding 47. A P-47M, or a D with 72inches of boost would have been more reasonable. And in reality, even in late 44 early 45, most of the German luftwaffe was A model 190s and G-14s. Only about 25% of 109s in jan45 were K models, and none of them had 1.98ata.

 

BUT

 

The real problem with the employment of the P-47 in the game right now is spotting. The extremely short distance of spotting, and the extreme difficulty of seeing even at close ranges basically confounds the use of the P-47. In reality, a P-47 could be between 20-30,000ft (where anything that came up to it could be outran or out turned), and still observe planes at sea level in order to dive on them.  (especially since everyone was going about in formations and not by themselves) Fighter sweeps flown over the continent by thunderbolts were regularly flown at exceptionally high altitudes, around 30,000 feet. People were not buzzing around below 10,000ft if they had any choice in the matter. Il2 spotting issues make it so that high altitude stalking is basically impractical because you will very rarely see anyone below you and will be orbiting at 25,000ft for no reason. It is also exceptionally difficult to employ the sort of tactics that Thunderbolts employed in BnZ because you cannot maintain the correct level of SA compared to real life once you commit to an attack.

 

The other big reason that the Thunderbolt is limited in the game is due to the nature of the multiplayer experience. You have a constant stream of single or double aircraft groups coming from their bases to the front line. It is also generally not allowed to target airbases, which IRL would have been the main targets. So what ends up happening is that unless you restrict yourself to a single pass, you are bound to have someone you didnt stand much change of seeing come into your fight ever 30 seconds or so. IRL you would have found an enemy group and attacked it, and while it was certainly not impossible for aircraft to enter the battle after it had started, it was far less likely than we have in game.

 

Additionally, the 47 we have as absurd engine limits that are odd even by the standards of this game. Any use of WEP bleeds your combat power too, in a plane that desperately needs its maximum boost. We also dont have the "correct" "time" of WEP. So you end up having to spend most of your time at continuous power, while your opponents have 10min of wep and a continuous power that is much less debilitating.

 

So in summary, in il2 you spend most of your time taking a run of the mill 47 up against the very best 109s and 190s. And you have to do this at low altitudes the 47 was not meant for, and you cant use your engine they way you should.

 

But....you do have flaps....

Edited June 9, 2020 by [TLC]MasterPooner

[-332FG-Buddy]

3 minutes ago, [TLC]MasterPooner said:

So as many people have pointed out already, alot of this has to do with the fact that in multiplayer you are only facing the pinnacle of German piston fighters but not in a corresponding 47. A P-47M, or a D with 72inches of boost would have been more reasonable. And in reality, even in late 44 early 45, most of the German luftwaffe was A model 190s and G-14s. Only about 25% of 109s in jan45 were K models, and none of them had 1.98ata.

 

BUT

 

The real problem with the employment of the P-47 in the game right now is spotting. The extremely short distance of spotting, and the extreme difficulty of seeing even at close ranges basically confounds the use of the P-47. In reality, a P-47 could be between 20-30,000ft (where anything that came up to it could be outran or out turned), and still observe planes at sea level in order to dive on them.  (especially since everyone was going about in formations and not by themselves) Fighter sweeps flown over the continent by thunderbolts were regularly flown at exceptionally high altitudes, around 30,000 feet. People were not buzzing around below 10,000ft if they had any choice in the matter. Il2 spotting issues make it so that high altitude stalking is basically impractical because you will very rarely see anyone below you and will be orbiting at 25,000ft for no reason. It is also exceptionally difficult to employ the sort of tactics that Thunderbolts employed in BnZ because you cannot maintain the correct level of SA compared to real life once you commit to an attack.

 

The other big reason that the Thunderbolt is limited in the game is due to the nature of the multiplayer experience. You have a constant stream of single or double aircraft groups coming from their bases to the front line. It is also generally not allowed to target airbases, which IRL would have been the main targets. So what ends up happening is that unless you restrict yourself to a single pass, you are bound to have someone you didnt stand much change of seeing come into your fight ever 30 seconds or so. IRL you would have found an enemy group and attacked it, and while it was certainly not impossible for aircraft to enter the battle after it had started, it was far less likely than we have in game.

Well said!

[ICDP]

8 hours ago, Legioneod said:

Keep in mind that above and ahead in this situation are to separate things, it doesn't mean the P-47 was right in front of the Zero the whole time.

P-47 wasn't like this with a direct line of fire from the zero.

 

It was more similar to this or this: (Thats not a gun solution, the P-47 was safe at that point. Keywords are 600ft above and far ahead) The Zero would of had to pull up to fire and would have lost even more energy which would allow the P-47 to gain even more of an advantage. Not of this actually matters but I notice people seems to ignore the Above vs Ahead part.

 

I think its a bit too stiff as well but I'm not 100% sure. If anything this report would tell us but I'm not sure how to interpret it or even apply it in-game for test.

 

Measurements of flying qualities of P-47D airplane to determine longitudinal stability and control and stalling characteristics.

http://www.wwiiaircraftperformance.org/p-47/Naca_TN_2899__F-47D-30_Flight_Test.pdf

 

Part of this is because the P-47 doesn't get it's historical power up high, it's only making 52-53" when it should be making 56" at 29,000ft, this would give it around 435-443 mph at 29,000ft. The power available at higher altitudes is incorrect in-game.

 

The problem is the P-47 elevator seems to stiffen up too early to the point of not pulling full deflection. This makes it impossible to blackout the pilot at higher speeds unless you use trim. Clearly the elevators get stiff but my question is are they getting stiff too soon and should we be able to pull full deflection at higher speeds.

 

Yet the trials between the A6M5 seems to indicate the P-47 to be on par if not slightly better than the P-51. at least in zoom. Certainly the P-51 wasn't superior by any large margin if at all.

While these test are helpful for getting an idea imo they are too vague sometimes, we don't know all of the conditions.

 

 

And just so people can see them again and maybe make more sense out of them than I can, here are just a few reports, There is more but I don't have them right now.

 

Flight investigation of boundary layer and profile drag characteristics of smooth wing sections of P-47 airplane.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093001.pdf

 

Flight investigation at high speeds of profile drag of wing of a P-47D airplane having production surfaces covered with camouflage paint.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092751.pdf

 

Measurements of flying qualities of P-47D airplane to determine lateral and directional stability and control characteristics.

http://www.wwiiaircraftperformance.org/p-47/Naca_TN_2675__F-47D-30_Flight_Test.pdf

 

 

Measurements of flying qualities of P-47D airplane to determine longitudinal stability and control and stalling characteristics.

http://www.wwiiaircraftperformance.org/p-47/Naca_TN_2899__F-47D-30_Flight_Test.pdf

 

NASA Website so you can look up any other report you want.

https://ntrs.nasa.gov/search.jsp?Nm=17|Collection|NACA||4294059423|Publication Year|1945&N=0&No=30

 

Those diagrams, are they from the test, or just your interpretation?  The test result specifically states above and far ahead, your diagram shows above and marginally ahead and would not be what I would interpret as "far ahead".  Not trying to be picky but the point was to show that a Zeke is 400-600ft below after a dive and zoom then a 109 or Fw will be even closer.  This is shown to be true in the P-47D vs Fw190 tactical trials where the Fw190 had an initial advantage and it took the P47D 7,000ft to catch it in a dive.  So the point of me posting those tac trials was to help manage people's expectations and show that any performance advantage in contemporary WWII fighters is marginal.

 

The P-47D in sim gets 54"-55" Hg at 29,000ft, so it's slightly lower but not massively so.  IAS for me on Spring Kuban map at 29,250 ft was 255mph.  OAT was -40c according to the He111 OAT gauge.  When we put those into a TAS calculator we get 433mph TAS.  Which is right on the money for performance.

 

 

The P51D-5 in the tactical trials test was run at 62" Hg, the in sim one does 67" (or 75" with 150 Octane).  The P47D in the trials has the same manifold pressure as the in sim version as tested.  So our P51D in sim is running higher manifold pressure and will give slightly better results.

 

In the interest of science I did a quick few tests at 62" Hg in the P51D.

 

• 5,000 feet alt.  200IAS
• Entered a dive of roughly 30-35 degree and rapidly reached VNE at around 18,000.  I began a roughly 2G-3G pull-out at 20,000 feet.  Speed at ~1600 was ~418 mph
• Began pulling out at ~2-3G and levelled out at just over 16,000 feet.  Speed lost during pullout to climb was ~40 mph IAS.
• Pulled through into a ~40 degree climb.
• Continued climb until stall speed.
• Final altitude was ~22,600 feet and 145mp IAS

 

So marginally worse than the in sim P47D.

 

I didn't mention previously but I had trim set to 50% nose up on all aircraft to help ensure a smooth pull-out from the dive.  The P51D and P47D both have considerable nose down trim set by default.

 

P.S.  I think it's a bit of a stretch to start claiming we don't have enough info from these tac trials as they don't state conditions.  The tests were done with aircraft side by side so atmospheric/weather conditions were identical for each aircraft during the tests.  They even state the Zeke was running below optimal until they made some adjustments and that it had a rough paint surface but should not impact results too much.

Edited June 9, 2020 by ICDP

[Talon_]

4 hours ago, II./SG.1-MarkWilhelmsson said:

 

Yea but I mean to his credit above others, this guy didn't just fly one, he OWNED one. Hahaha

 

Are we about to cross that line where we say that the word of a real life P47 pilot who has tried the IL2 version isn't good enough? This forum may just be a clown world after all hahaha

 

He owned one but his one most likely doesn't have a working turbo and if it did then it's suspect that he didn't notice the critical altitude is wrong.

[ICDP]

The general handling and feel would be valid.

4 hours ago, II./SG.1-MarkWilhelmsson said:

 

Yea but I mean to his credit above others, this guy didn't just fly one, he OWNED one. Hahaha

 

Are we about to cross that line where we say that the word of a real life P47 pilot who has tried the IL2 version isn't good enough? This forum may just be a clown world after all hahaha

 

I'm afraid that yes, this is how these things go.  If the expert's feedback does not fit the narrative, or the real life factual data contradicts their "feels", then Instead of adjusting their assumptions and world view to match the actual facts they simply dismiss them as "invalid".

Edited June 9, 2020 by ICDP

[Legioneod]

1 hour ago, ICDP said:

 

Those diagrams, are they from the test, or just your interpretation?  The test result specifically states above and far ahead, your diagram shows above and marginally ahead and would not be what I would interpret as "far ahead".  Not trying to be picky but the point was to show that a Zeke is 400-600ft below after a dive and zoom then a 109 or Fw will be even closer.  This is shown to be true in the P-47D vs Fw190 tactical trials where the Fw190 had an initial advantage and it took the P47D 7,000ft to catch it in a dive.  So the point of me posting those tac trials was to help manage people's expectations and show that any performance advantage in contemporary WWII fighters is marginal.

 

The P-47D in sim gets 54"-55" Hg at 29,000ft, so it's slightly lower but not massively so.  IAS for me on Spring Kuban map at 29,250 ft was 255mph.  OAT was -40c according to the He111 OAT gauge.  When we put those into a TAS calculator we get 433mph TAS.  Which is right on the money for performance.

 

 

The P51D-5 in the tactical trials test was run at 62" Hg, the in sim one does 67" (or 75" with 150 Octane).  The P47D in the trials has the same manifold pressure as the in sim version as tested.  So our P51D in sim is running higher manifold pressure and will give slightly better results.

 

In the interest of science I did a quick few tests at 62" Hg in the P51D.

 

• 5,000 feet alt.  200IAS
• Entered a dive of roughly 30-35 degree and rapidly reached VNE at around 18,000.  I began a roughly 2G-3G pull-out at 20,000 feet.  Speed at ~1600 was ~418 mph
• Began pulling out at ~2-3G and levelled out at just over 16,000 feet.  Speed lost during pullout to climb was ~40 mph IAS.
• Pulled through into a ~40 degree climb.
• Continued climb until stall speed.
• Final altitude was ~22,600 feet and 145mp IAS

 

So marginally worse than the in sim P47D.

 

I didn't mention previously but I had trim set to 50% nose up on all aircraft to help ensure a smooth pull-out from the dive.  The P51D and P47D both have considerable nose down trim set by default.

 

P.S.  I think it's a bit of a stretch to start claiming we don't have enough info from these tac trials as they don't state conditions.  The tests were done with aircraft side by side so atmospheric/weather conditions were identical for each aircraft during the tests.  They even state the Zeke was running below optimal until they made some adjustments and that it had a rough paint surface but should not impact results too much.

I'm unable to get 54" My manifold stays around 52-53 even with WEP. What we should be getting is 56" and top speed of 435-443mph at 29,000ft. Autumn map should be used for tsting as it will give standard atmospheric pressures and temps and more acurate results.

Edited June 9, 2020 by Legioneod

[ICDP]

Just now, Legioneod said:

I'm unable to get 54" My manifold stays around 52-53 even with WEP. What we should be getting is 56" and top speed of 435-443mph.

 

The chart I posted shows around 430 - 435 at 29,000 - 30,000 in multiple P-47D tests.  I got 433 TAS so again pretty much right where the charts show it should be.

[Legioneod]

6 minutes ago, ICDP said:

 

The chart I posted shows around 430 - 435 at 29,000 - 30,000 in multiple P-47D tests.  I got 433 TAS so again pretty much right where the charts show it should be.

I'd do the test again on the autum map for accurate results, devs have said to use the autum map when testing for speed performance. If it can't achieve it on the autum map then something is off.

59 minutes ago, ICDP said:

The general handling and feel would be valid.

 

I'm afraid that yes, this is how these things go.  If the expert's feedback does not fit the narrative, or the real life factual data contradicts their "feels", then Instead of adjusting their assumptions and world view to match the actual facts they simply dismiss them as "invalid".

I wasn't refuting what the man said at all, I was just making a point that other sims use real pilots for input as well yet sometimes the flight model is vastly different to other intepretations.

My point is that if one pilot says one sim is good while another pilot says the other sim is correct then who do we believe?

Edited June 9, 2020 by Legioneod

[Atomic_Spaniel]

14 minutes ago, Legioneod said:

My point is that if one pilot says one sim is good while another pilot says the other sim is correct then who do we believe?

 

In my limited experience (glider pilots and the Condor flight sim) RL pilots are absolutely terrible at telling whether a sim is accurate or not. They notice mostly the differences between full-size controls and PC peripherals, the lack of physical feedbacks and the reduced SA we get from a monitor. They don't notice that the sink rate of the ASW-19 is off by 20% at 70 kts.

 

A better bet might be to use quantitative data from RL pilot accounts to validate the sim FMs. Obviously, we have to be careful because there is a lot of self-evident braggadocio in pilot stories (P-47 out rolls anything, anybody?). However, when accounts give specific details, such as speed loss when pulling g, then they can be quite useful. Except of course if the account contradicts what we have already decided, e.g., 

 

Poster 1: The P-47 was famous for not losing energy at speed.

Poster 2: Here is a thoughtful and detailed account of flying the P-47 by a pilot who flies a P-47 and other warbirds at air displays, he says it loses more energy in manoeuvres than other warbirds.

Poster 1: The P-47 was famous for not losing energy at speed.

[ICDP]

I thought it was the spring map that was set for standard conditions?

 

You are correct about pilot accounts can vary, but test data with conditions outlined can not in any way be described as "vague".  We know the tests were carried out side by side in identical conditions for each plane so the results are as good as we can get.

[Tbolt47]

48 minutes ago, Legioneod said:

I'm unable to get 54" My manifold stays around 52-53 even with WEP. What we should be getting is 56" and top speed of 435-443mph at 29,000ft. Autumn map should be used for tsting as it will give standard atmospheric pressures and temps and more acurate results.

 

It also doesn't help that these test were done with a D-10 and D-22 and of course we are running a D-28. Also they used three different props, but not the asymmetric prop our D-28 has.

[Legioneod]

22 minutes ago, Tbolt47 said:

 

It also doesn't help that these test were done with a D-10 and D-22 and of course we are running a D-28. Also they used three different props, but not the asymmetric prop our D-28 has.

True but the D-10 and D-22 eventually could all use the same power settings, weight was nearly identical across all the D blocks. I do think the D-22 has slighlty better performance than the D-28 so that should be factored in but it should still be within 10-15mph. I'm not sure of the perofmance figures for the A.O. Smith vs the Curtis or Hamilton but it seems the model in game shows figures close enough the the Curtis (even though its and A.O. Smith)

46 minutes ago, ICDP said:

I thought it was the spring map that was set for standard conditions?

 

You are correct about pilot accounts can vary, but test data with conditions outlined can not in any way be described as "vague".  We know the tests were carried out side by side in identical conditions for each plane so the results are as good as we can get.

I meant vauge as in some of the words used to describe the outcome. Whats far ahead? Is it 100 ft or 2000ft? Makes a difference. Same situation when we see test reports stating the P-47 could "easily" outdive a certain aircraft, what exactly is outdive? Is it a few hundred yards ahead or much greater/shorter distance?

We can get a decent idea from these reports but we can never be 100% certain if the model in game "correct", there's always going to be some level of interpretation and we can't get everything 100% accurate.

Is the ingame model wrong? In some ways yes but it does have other things right as well. It's ok overall but there's room for improvment.

[Tbolt47]

Just now, Legioneod said:

True but the D-10 and D-22 eventually could all use the same power settings, weight was nearly identical across all the D blocks. I do think the D-22 has slighlty better performance than the D-28 so that should be factored in but it should still be within 10-15mph. I'm not sure of the perofmance figures for the A.O. Smith vs the Curtis or Hamilton but it seems the model in game shows figures close enough the the Curtis (even though its and A.O. Smith)

 

Nearly identical weights, it's still going to have an effect - the R-2800-59 used in the D-28 was slightly heavier to start with, then there could be a small aerodynamic difference between a razorback and bubbletop, it all adds up to possible differences in climb performance and speed. It would just be nice to have data closer to what we have in game. When you say the game figures are close enough to the Curtiss do you mean to the 836-2C2 paddle blade?

 

 

[Legioneod]

7 minutes ago, Tbolt47 said:

 

Nearly identical weights, it's still going to have an effect - the R-2800-59 used in the D-28 was slightly heavier to start with, then there could be a small aerodynamic difference between a razorback and bubbletop, it all adds up to possible differences in climb performance and speed. It would just be nice to have data closer to what we have in game. When you say the game figures are close enough to the Curtiss do you mean to the 836-2C2 paddle blade?

 

 

Speed wise there was very little difference between the razorbacks vs the bubletops, (within a few mph) What really mattered was the power and prop used.

A D-23 and a D-26 for instance have similar top speeds when using same powers and similar weights.

 

Yes the Curtis 836-2C2 which is the standard paddle blade found on most P-47s during the latter part of the war, Hamilton and A.O. Smith were  uncommon by comparison.

The figures aren't perfect but they are somewhat close to real test results at least the lat time I tested it. (Main errors being in high altitude power being too low)

 

One large benefit of getting the D-22 is that we'll have better test material to refer to even though the prop and engine used in some test is different we can always factor this in.

Edited June 9, 2020 by Legioneod

[Tbolt47]

1 minute ago, Legioneod said:

Speed wise there was very little difference between the razorbacks vs the bubletops, (within a few mph) What really mattered was the power and prop used.

A D-23 and a D-26 for instance have similar top speeds when using same powers and similar weights.

 

Yes the Curtis 836-2C2 which is the standard paddle blade found on most P-47s during the latter part of the war, Hamilton and A.O. Smith were more uncommon by comparison.

The figures aren't perfect but they are somewhat close to real test results at least the lat time I tested it. (Main errors being in high altitude power being too low)

 

I know the prop was very important but we don't know quite where the asymmetric prop lies in comparison, I was just saying it would be nice to get some data on it to be sure anyway when we get the D-22 with the HS prop we can see more accurately how that performs.

 

Where did you get the info about the symmetrical prop being a lot more common late war? Just looking at photos? Also if this is the case was it down to performance or availability of the asymmetric prop?

 

 

[Legioneod]

1 minute ago, Tbolt47 said:

 

I know the prop was very important but we don't know quite where the asymmetric prop lies in comparison, I was just saying it would be nice to get some data on it to be sure anyway when we get the D-22 with the HS prop we can see more accurately how that performs.

 

Where did you get the info about the symmetrical prop being a lot more common late war? Just looking at photos? Also if this is the case was it down to performance or availability of the asymmetric prop?

 

 

On most blocks the Curtis 836-2C2 is listed as being standard from the factory (D-22, D-25, and D-27 being the only ones fitted with a Hamilton) As far as I know the D-28 was one of the few that sometimes had the A.O. Smith prop instead of the Curtis prop. On the model specifications for the D blocks I don't even see the A.O. Smith being listed anywhere in the document (may have just missed it)

[Tbolt47]

15 minutes ago, Legioneod said:

On most blocks the Curtis 836-2C2 is listed as being standard from the factory (D-22, D-25, and D-27 being the only ones fitted with a Hamilton) As far as I know the D-28 was one of the few that sometimes had the A.O. Smith prop instead of the Curtis prop. On the model specifications for the D blocks I don't even see the A.O. Smith being listed anywhere in the document (may have just missed it)

 

Okay, but we know there was plenty of prop changes to other versions, so what was fitted at the factory doesn't show what was common or not. There's plenty of pictures of D-27's, D-30's and late  razorbacks with asymmetric props fitted.

[ICDP]

2 hours ago, Legioneod said:

I'd do the test again on the autum map for accurate results, devs have said to use the autum map when testing for speed performance. If it can't achieve it on the autum map then something is off.

 

I just did the same test on the Kuban Autumn map.  OAT was -40c at best because the he111 OAT gauge was at it's minimum.

 

IAS 252 mph at 29520 feet.  That works out at roughly 427 TAS.  Hg was 54" as per manifold pressure gauge.

 

IAS 244 mph at 31166 feet.  430 TAS, Hg was only 51", though speed seems spot on

 

What I did notice was I had to have the intercooler flaps fully open to reach the best manifold pressure.  The real tests were done with intercooler flaps neutral.

 

 

 

 

Edited June 9, 2020 by ICDP

[Legioneod]

28 minutes ago, ICDP said:

 

I just did the same test on the Kuban Autumn map.  OAT was -40c at best because the he111 OAT gauge was at it's minimum.

 

IAS 252 mph at 29520 feet.  That works out at roughly 427 TAS.  Hg was 54" as per manifold pressure gauge.

 

IAS 244 mph at 31166 feet.  430 TAS, Hg was only 51", though speed seems spot on

 

What I did notice was I had to have the intercooler flaps fully closed to reach the best manifold pressure.  The real tests were done with intercooler flaps neutral.

 

 

 

 

I have a chart that list all the temps/pressures at certain altitudes. It's what I use and would be more accurate than the He111 guage. I'll post some results and the chart when I get on my pc later.

51" wouldn't produce enough power to get to 430mph TAS, TAS for your 244mph would be closer to 390-400 mph tas at 31k alt (at least from the numbers I used could be more but I dont have the chart infront of me, just did a quick search for some numbers)

Keep in mind this chart is without water injection for 52" and 56" but even 52" with Water wouldnt produce  430mph TAS. Chart shows around 410mph for 52" at 31k.

 

Edited June 9, 2020 by Legioneod

[ICDP]

Tested again at 29500 feet. Autumn map.  I used neutral oil and intercooler settings as per RL test.  51" Hg was the best manifold pressure.

 

258 IAS reached.

 

If we assume -47c then TAS at 29,500ft would be 431 at 258mph IAS.

If we assume -45c then TAS at 29,500ft  would be 433 at 258 mph IAS

 

The P51D reached 270 at the same altitude with stock engine.  Standard atmospheric charts how temp at that alt of around -44c -47c.

 

 

I also tested again at 31,250ft with intercoolers at neutral and got 247 mph IAS.

Edited June 9, 2020 by ICDP

[69th_Mobile_BBQ]

27 minutes ago, ICDP said:

Tested again at 29500 feet. Autumn map.  I used neutral oil and intercooler settings as per RL test.  51" Hg was the best manifold pressure.

 

258 IAS reached, so the 244 number was not fully valid as I had a bit too much drag (but a further test yielded 247 mph at 31,250ft).

 

If we assume -47c then TAS at 29,500ft would be 431 at 258mph IAS.

If we assume -45c then TAS at 29,500ft  would be 433 at 258 mph IAS

 

The P51D reached 270 at the same altitude with stock engine.  Standard atmospheric charts how temp at that alt of around -44c -47c.

 

 

I notice by your screenshot, you're running the oil a bit cold and over-speeding the turbo.  I wonder if you would get similar results if you kept the oil around 100 degrees and backed off on the turbo a bit.   

 

According to Greg's Airplanes and Automobiles YouTube, keeping the temperatures at an exact range is important. Too high or too low will result in loss of a fair amount of horsepower.  That is, of course, if it is actually modelled in-game.  I know 80 degrees is fine for a Yak but, the P-47 might be a bit different in that regard.  

[ICDP]

To be honest I'm not an expert in flying the P47 or any other plane.  I just wanted to see how fast they could go with just going full throttle.  The fact that even without optimising temps and settings I can get close to real speeds shows that not much is wrong with the top speeds.

 

For further reference, all at 29,500 ft.

 

Fw190D9 at same alt: 251 mph IAS

Bf109K4 (both versions) 263 mph IAS

Bf109G14: 244 mph IAS

P51D stock: 270 mph IAS

P51D 150 octane: 274 mph IAS

P47D: 258 mph IAS.

 

The P51D seems a touch faster than it should be? Though I think the others all line up reasonably well.

Edited June 9, 2020 by ICDP

[Legioneod]

1 hour ago, ICDP said:

Tested again at 29500 feet. Autumn map.  I used neutral oil and intercooler settings as per RL test.  51" Hg was the best manifold pressure.

 

258 IAS reached.

 

If we assume -47c then TAS at 29,500ft would be 431 at 258mph IAS.

If we assume -45c then TAS at 29,500ft  would be 433 at 258 mph IAS

 

The P51D reached 270 at the same altitude with stock engine.  Standard atmospheric charts how temp at that alt of around -44c -47c.

 

 

I also tested again at 31,250ft with intercoolers at neutral and got 247 mph IAS.

 

258 IAS is 417 TAS at -45c and 415 TAS at -47c.

[ICDP]

5 minutes ago, Legioneod said:

 

258 IAS is 417 TAS at -45c and 415 TAS at -47c.

 

As you can see all other aircraft have similar speed or lower speeds at roughly what is to be expected performance deltas, only P51D a tad faster than advertised.

Edited June 9, 2020 by ICDP

[Legioneod]

1 hour ago, ICDP said:

To be honest I'm not an expert in flying the P47 or any other plane.  I just wanted to see how fast they could go with just going full throttle.  The fact that even without optimising temps and settings I can get close to real speeds shows that not much is wrong with the top speeds.

 

For further reference, all at 29,500 ft.

 

Fw190D9 at same alt: 251 mph IAS

Bf109K4 (both versions) 263 mph IAS

Bf109G14: 244 mph IAS

P51D stock: 270 mph IAS

P51D 150 octane: 274 mph IAS

P47D: 258 mph IAS.

 

The P51D seems a touch faster than it should be? Though I think the others all line up reasonably well.

So all the others seems pretty close (except the P-47) I do agree the P-51 does seem a bit faster than it should be but I don't know enough about it to be sure.

Top speed for 29000ft 150fuel seems to be listed around 425.

5 minutes ago, ICDP said:

 

As you can see all other aircraft have similar speed or lower speeds at roughly what is to be expected performance deltas, only P51D a tad faster than advertised.

Yes but the P-47 is off by up to 20mph at 29,000ft

Edited June 9, 2020 by Legioneod

[ICDP]

2 hours ago, Legioneod said:

So all the others seems pretty close (except the P-47) I do agree the P-51 does seem a bit faster than it should be but I don't know enough about it to be sure.

Top speed for 29000ft 150fuel seems to be listed around 425.

Yes but the P-47 is off by up to 20mph at 29,000ft

 

Can I ask where you calculated this from?

[CountZero]

On that alt you can get to 270mph ias by manualy increseng rpm to ~2900rpm, it will not brake engine untill timer run out for combat mode. Making inlet 65% and going almost to 3000rpm i was doing 273mph for few min untill bosted time mode run out and brake engine.

[Raven109]

20 hours ago, Tomsk said:

 

The P-38 (261 kg/m^2) has a higher wing loading than the P-47 (207 kg/m^2) ...

 

 

Perhaps, but that's still a very large difference to explain. The P-38 is not renowned for it's awesome acceleration. In any case I stand by my claims, now with solid data to back them up:

• The P-47 does not handle well at high-speeds: unlike the P-51, P-38 or even the Spitfire it cannot pull enough G to reach the blackout limit at 400mph.
• The P-47 bleeds energy faster than any other comparable plane in high-speed maneuvers: even planes that are heavier, with higher wing loading, pulling more G.
• It is not like this in any other simulation: only in IL2:GB.

It's possible that this is all entirely explainable, and makes perfect sense but to my mind this seems enough evidence to warrant some investigation by the dev team: it certainly is very odd. This could indeed be correct, but it could also easily just be a simple bug.

 

From what I can tell, you're not using trim, that's why you don't black out.

 

I can consistently black out in a P-47 when using trim in a flat turn starting at 400mph. More trim is needed if the fuel tank is full. As the tests for the C model conclude, elevator control is noticeably better when the auxiliary tank (aka the rear tank) is empty.

 

From tests performed on the P-47C (http://www.wwiiaircraftperformance.org/p-47/p-47c-afdu.html).

 

I think trim is needed because it's considered that the pilot is not able to achieve full stick deflection by his own power. Even the manual states that if you need to go at high speeds you should trim the aircraft tail heavy.

 

P-47 manual:

 

The plane does enter a high speed stall if you try to make the turn tight, as described by the manual, so I don't see anything wrong there. I avoid this by keeping the ball in the middle.

 

From the 47 manual:

 

Trim is very useful when booming and zooming, on all planes...

Edited June 9, 2020 by Raven109

[Raven109]

18 hours ago, Bremspropeller said:

 

You should fix that!

A lot of fun to fly.

Perhaps, sometime in the (near?) future. I always felt, from flying the 38 in il2'46, that its tail booms block the view too much, for my taste. But maybe it's just something to get used to.

 

[Legioneod]

3 hours ago, CountZero said:

On that alt you can get to 270mph ias by manualy increseng rpm to ~2900rpm, it will not brake engine untill timer run out for combat mode. Making inlet 65% and going almost to 3000rpm i was doing 273mph for few min untill bosted time mode run out and brake engine.

You shouldn't have to do this in order to get those speeds. You should be able to get the proper power by running 56" 2700rpm. Just because you can get those speeds by gaming the game doesn't mean it's modeled corectly. If you can't get it the proper way then it's not correct.

4 hours ago, ICDP said:

 

Can I ask where you calculated this from?

There;s alot of different TAS calculators online. Thats what I use. If you use proper data it gives you accurate results.

[ICDP]

15 minutes ago, Legioneod said:

You shouldn't have to do this in order to get those speeds. You should be able to get the proper power by running 56" 2700rpm. Just because you can get those speeds by gaming the game doesn't mean it's modeled corectly. If you can't get it the proper way then it's not correct.

There;s alot of different TAS calculators online. Thats what I use. If you use proper data it gives you accurate results.

 

Agreed, we should not have to use gaming trick to get better performance.

 

I tried a few different IAS to TAS converters and some give very different results.  I then read that standard altimeter setting should be 29.92 and once I changed to that from a default of 28.16, the TAS result changed from 434 to 417 (temp set was -45c).

 

So TAS for the different aircraft at 29,522ft is.

 

Fw190D9: 405 mph TAS

Bf109K4 (both versions) 425 mph TAS

Bf109G14: 394 mph TAS

P51D stock: 426 mph TAS

P51D 150 octane: 443 mph TAS

P47D: 417 mph TAS

 

So yeah, it is underperforming at this altitude by ~ 15-20 mph.  I will do some further testing at various altitudes and compare to RL data.  When I compile that I will make a report on the beta tester forum.  Though I can't promise anything will be fixed at least I can bring this to the devs attention in a more direct fashion.

 

 

[Legioneod]

1 minute ago, ICDP said:

 

Agreed, we should not have to use gaming trick to get better performance.

 

I tried a few different IAS to TAS converters and some give very different results.  I then read that standard altimeter setting should be 29.92 and once I changed to that from a default of 28.16, the TAS result changed from 434 to 417 (temp set was -45c).

 

So TAS for the different aircraft at 29,522ft is.

 

Fw190D9: 405 mph TAS

Bf109K4 (both versions) 425 mph TAS

Bf109G14: 394 mph TAS

P51D stock: 426 mph TAS

P51D 150 octane: 443 mph TAS

P47D: 417 mph TAS

 

So yeah, it is underperforming at this altitude by ~ 15-20 mph.  I will do some further testing at various altitudes and compare to RL data.  When I compile that I will make a report on the beta tester forum.  Though I can't promise anything will be fixed at least I can bring this to the devs attention in a more direct fashion.

 

 

I was planning on doing this as well, was just waiting for the right time.

[ICDP]

A few tests done at SL and 7000m (22,966ft).

 

SL: 350mph TAS

22,966ft: 436mph TAS

 

These are pretty much spot on compared to RL tests.  I could do more tests at altitudes in between but I don't think we will see problems.  So it looks like the problem is once we start going to higher altitudes.

Edited June 9, 2020 by ICDP

[Legioneod]

6 minutes ago, ICDP said:

A few tests done at SL and 7000m (22,966ft).

 

SL: 350mph TAS

22,966ft: 436mph TAS

 

These are pretty much spot on compared to RL tests.  I could do more tests at altitudes in between but I don't think we will see problems.  So it looks like the problem is once we start going to higher altitudes.

Yep. Problem starts once you hit critical altitude for 64" which is somewhere around 24,000ft. The power drops off too quickly and we end up getting less power than we should at 29,000ft.

Critical altitude for 56" should be somewhere around 29,000-29,500ft.

 

[CountZero]

1 hour ago, Legioneod said:

You shouldn't have to do this in order to get those speeds. You should be able to get the proper power by running 56" 2700rpm. Just because you can get those speeds by gaming the game doesn't mean it's modeled corectly. If you can't get it the proper way then it's not correct.

There;s alot of different TAS calculators online. Thats what I use. If you use proper data it gives you accurate results.

Thats what they used for P-47D 28, and when you test it in game you get similar numbers, on 5000ft its 3mph slower, on 15000ft its exactly as that speed, and critical 437mph it gets at 23500ft insted at 24500ft like in document shown, when using same setings.

[Legioneod]

2 minutes ago, CountZero said:

Thats what they used for P-47D 28, and when you test it in game you get similar numbers, on 5000ft its 3mph slower, on 15000ft its exactly as that speed, and critical 437mph it gets at 23500ft insted at 24500ft like in document shown, when using same setings.

I have the report that they mention.

At lower altitudes it is correct for the most part. But the critical altitude for 56" is incorrect in-game. Irl it was around 29,000ft but in-game it's lower than it should be.

Edited June 9, 2020 by Legioneod

[CountZero]

1 minute ago, Legioneod said:

I have the report that they mention.

At lower altitudes it is correct for the most part. But the critical altitude for 56" is incorrect in-game. Irl it was around 29,000ft but in-game it's lower than it should be.

By chart showing same P-47D-28 we have in game or other models with other propelers ? 

[Legioneod]

Just now, CountZero said:

By chart showing same P-47D-28 we have in game or other models with other propelers ? 

Other models or prop doesn't matter (for the most part) because the power available remains the same. The D-22 through the D-30 used the same engine and turbo setup so power available at certain altitudes remained constant, they didn't change just because a different prop was used.

 

Here's a D-26 vs D-28 for comparison. They both are bubbletops with the same engine/turbo and prop configuration. Only reason CA are different is because the D-26 is using 56" and the D-28 is using 64". The D-28 could still achieve 56" at 29000' even though it's top power critical altitude was far lower (24500' at 64")