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I./ZG1_Dutchvdm

P-47 vs P-51/P-38

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Hi Guys,

 

I must say that i enjoy the new addition's very much, but after some testing, i have a slight feeling that both the P-51 and even the P-38 "outshine" the P-47 at lower altitudes by quite a large margin. Especially below 10.000 feet the P-47 feels like a dog compared to the other two. For the P-51 this might be what someone might expect, but even the P-38 (which is a very heavy fighter) feels far more nimble and picks up speed much faster. I always thought that the P-47 was at least better then the P-38 in most regards, but in BOBP it seems the other way around. 

 

Am i missing anything?

 

Grt M  

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Full weight for the P-47 is around 12 tons compared to the P-38's 17 tons. But you also have to realize the P-38 is running two engines. Both being Allison 1710 v12 engines. You're going to have a much better power to weight ratio compared to the P-47 which is why the lightning feels better even at low altitude compared to the thunderbolt

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1 minute ago, TheOldCrow said:

Full weight for the P-47 is around 12 tons compared to the P-38's 17 tons.

 

Make that half that figure for both aircraft. Power to weight is not much different between the two, in all out mode the advantage is with the P-47, but total power is better with the P-38. All in all there isn't much to chose between the two.

 

The P-47 is a high altitude fighter used at low altitude when it ran out of targets up high. It worked very well down low, but it cannot be expected to work miracles at low altitude. Personally I also find the P-38 and P-51 to be better, probably beyond the point that numbers would make me expect. But then I never really cared about low altitude fighting in the P-47, so it might be the pilot.

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P-38 was a very agile fighter contrary to pop-opinion. Its poor agility rep was earned from pilot anecdote when the USAAF was cutting its teeth for the first time. It has huge Fowler flaps and will out turn anything int he game that is not the spitfire.

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I was amazed how well the P-51 and P-38 handle. The Tempest as well. I cant stand the P-47 so I expected the other American planes to be just as miserable. I was pleasantly surprised.

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On 10/7/2019 at 3:20 PM, I./ZG1_Dutchvdm said:

Am i missing anything?

 

IMHO the Thunderbolt also can be called a heavy fighter... with one (18 cylinder double radial + all air ducks, air-air inter-cooler and turbo) engine but still big and heavy.

In the game P-47D has limited use for ADI - only for 5m for straight use but carries 15m of supplies. The WEP has 2600hp in the game but +2800hp settings were also available.

But most important are tactics - now with the 9.5km visibility sphere gone it should be possible to use some altitude to good effect.

 

Staying very low without cover of other friendly fighters is ill advised. That's true even if you are driving the 150 octane Spitfire.

Edited by Ehret

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Thanks for the input guys. I guess that i need to revise my opinion about the P-38.  One other thing that surprised me is the P-38 is very easy to fly. I don't know how misguided this can be, but i read a quote a while back about the complexity of operating the P-38.

 

Rau wrote that he was being asked to put kids fresh from flight school into P-38 cockpits and it wasn’t working. He asked his boss to imagine “a pilot fresh out of flying school with about a total of twenty-five hours in a P-38, starting out on a combat mission.” Rau’s young pilot was on “auto lean and running on external tanks. His gun heater is off to relieve the load on his generator, which frequently gives out (under sustained heavy load). His sight is off to save burning out the bulb. His combat switch may or may not be on.” So, flying along in this condition, wrote Rau, the kid suddenly gets bounced by German fighters. Now he wonders what to do next.

“He must turn, he must increase power and get rid of those external tanks and get on his main [fuel tank],” Rau wrote. “So, he reaches down and turns two stiff, difficult gas switches (valves) to main, turns on his drop tank switches, presses his release button, puts the mixture to auto rich (two separate and clumsy operations), increases his RPM, increases his manifold pressure, turns on his gun heater switch (which he must feel for and cannot possibly see), turns on his combat switch and he is ready to fight.” To future generations this would be called multi-tasking, and it was not what you wanted to be doing when Luftwaffe fighters were pouring down on you.

“At this point, he has probably been shot down,” Rau noted, “or he has done one of several things wrong. Most common error is to push the throttles wide open before increasing RPM. This causes detonation and subsequent engine failure. Or, he forgets to switch back to auto rich, and gets excessive cylinder head temperature with subsequent engine failure.”

 

I hope some of this complexity comes when we have external tanks and more detailed fuel management. 

 

Grt M

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4 hours ago, I./ZG1_Dutchvdm said:

Thanks for the input guys. I guess that i need to revise my opinion about the P-38.  One other thing that surprised me is the P-38 is very easy to fly. I don't know how misguided this can be, but i read a quote a while back about the complexity of operating the P-38.

 

Rau wrote that he was being asked to put kids fresh from flight school into P-38 cockpits and it wasn’t working. He asked his boss to imagine “a pilot fresh out of flying school with about a total of twenty-five hours in a P-38, starting out on a combat mission.” Rau’s young pilot was on “auto lean and running on external tanks. His gun heater is off to relieve the load on his generator, which frequently gives out (under sustained heavy load). His sight is off to save burning out the bulb. His combat switch may or may not be on.” So, flying along in this condition, wrote Rau, the kid suddenly gets bounced by German fighters. Now he wonders what to do next.

“He must turn, he must increase power and get rid of those external tanks and get on his main [fuel tank],” Rau wrote. “So, he reaches down and turns two stiff, difficult gas switches (valves) to main, turns on his drop tank switches, presses his release button, puts the mixture to auto rich (two separate and clumsy operations), increases his RPM, increases his manifold pressure, turns on his gun heater switch (which he must feel for and cannot possibly see), turns on his combat switch and he is ready to fight.” To future generations this would be called multi-tasking, and it was not what you wanted to be doing when Luftwaffe fighters were pouring down on you.

“At this point, he has probably been shot down,” Rau noted, “or he has done one of several things wrong. Most common error is to push the throttles wide open before increasing RPM. This causes detonation and subsequent engine failure. Or, he forgets to switch back to auto rich, and gets excessive cylinder head temperature with subsequent engine failure.”

 

I hope some of this complexity comes when we have external tanks and more detailed fuel management. 

 

Grt M

Any other fighter that uses external tank would be subjected to a similar amount of procedures.

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Not necessarily so, there were simpler systems around. Or, to be precise, more complex systems that lowered the workload for the pilot.

 

Plus, having only one engine and that ideally with a Kommandogerät helps with a lot of other things.

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47 does decently well when it gets to use its full power, but on continuous it struggles. P51 and 38 have little issue doing their job on continuous, able to cruise and climb at good speed.

 

If you were able to use the water for its entire duration you'd honestly have zero issues in the 47. But right now its actually almost impossible to even use 15 mins of water during a single flight.

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I have been spending a lot of time with the P-38 and am also amazed at how nimble and maneuverable it is, you really have to push it hard to get into a high speed stall. The P-47 OTOH seems to go into a stall a lot easier and without much warning if you try to turn aggresively.

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On 10/9/2019 at 3:19 PM, JtD said:

Not necessarily so, there were simpler systems around. Or, to be precise, more complex systems that lowered the workload for the pilot.

 

Plus, having only one engine and that ideally with a Kommandogerät helps with a lot of other things.

 

I was referring to the fact that the sequential actions described in the text aren´t very disimilar to other done by other fighters in similar circumstances. If you are cruising with your drop tank selected, with your gunsight lamp off, and your gun heater off, then you have to do the same. Could be more or less difficult to access the different swichtes, levers and knobs, but the actions would be pretty much the same (except the double engines). Obviously, in german fighters is going to be easier to get into combat settings. But not by a huge marging. In any case, any fighter being bounced, while cruising in economical settings and with drop tanks in use, is going te be in a pickle. That regardless of the degree of automatism implanted.

Edited by HR_Zunzun
grammar

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On 10/10/2019 at 4:14 PM, Sgt_Joch said:

I have been spending a lot of time with the P-38 and am also amazed at how nimble and maneuverable it is, you really have to push it hard to get into a high speed stall. The P-47 OTOH seems to go into a stall a lot easier and without much warning if you try to turn aggresively.

don't forget to mention its combat flaps, makes the turns even tighter. and the use of dive brakes to keep from overshooting enemy a/c. also the P-38 seems to withstand ground fire about the same as P-47. the gun placement also makes it a better choice, i just set my convergence to 700m for ground attack and fighter mode.

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The issue with the P-38 procedures were the number of individual buttons and levers that had to be pressed to go from economy cruise *and* where they were located, and because they were not all in one spot, it was easy to get out of order and blow an engine. 

 

The P-47 and P-51 has all of the engine levers both next to each other and in the order you needed to push them: starting from the inside out: Mixture, RPM, Throttle, Boost. You could grab all of them at once and push all of them forward with one hand. It also had spring book's that would catch the RPM lever and push it forward if you did it wrong. 

 

Next time you load up the P-38, take a look at where the mixture, RPM, throttle and boost levers are all at. You can't do that one handed. 

 

Other things include, on the P-47, to drop tank you just needed one switch to switch from external to internal tanks, then pull the bomb drop handles. 

 

It also had a standard practice to keep the gun heat on. 

 

So the P-47 effectively had a six step process to go from cruise to combat (1: All levers forward+water, 2: switch tanks to internal, 3: arm racks, 4: pull bomb release, 5: arm Master arm, 6: turn on gunsight).

 

All of these levers are in easy view of the pilot too. Further the two biggest issues; accidentally pushing Throttle before RPM and the complex tank handling are either guarded against or considerably simpler in the P-47 than they were in the P-38. I'll need to check but I'm also given to understand that water injection does mitigate some of then issue with running over-lean,so you've got more time to catch it and correct too. 

 

Think is, we don't have those sort of ergonomic problems, because we can set up ideal ergonomics for ourselves. 

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With flaps deployed I'd expect the P-38 to have a decent turn performance, but without flaps it should be outturned by most of the single engined fighters quite readily.

 

Keep in mind that the wing loading of the P-38 is a rather hefty ~265 kg/sq.m., so it would need a very high lift coefficient to make up for this, something only the deployment of high lift devices can provide. The P-38 has the fowler flaps in this case, but they come with a massive drag penalty, so whilst these will help increase the instantanous turn performance I wouldn't expect the sustained turns to be improved.  

 

Haven't tried the P-38 ingame yet so can't say wether it's overperforming or not, but if it's outturning the single engined types then I'd argue there's an error in the FM, esp. if it manages to do this without the use of flaps.

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3 hours ago, Panthera said:

With flaps deployed I'd expect the P-38 to have a decent turn performance, but without flaps it should be outturned by most of the single engined fighters quite readily.

 

Keep in mind that the wing loading of the P-38 is a rather hefty ~265 kg/sq.m., so it would need a very high lift coefficient to make up for this, something only the deployment of high lift devices can provide. The P-38 has the fowler flaps in this case, but they come with a massive drag penalty, so whilst these will help increase the instantanous turn performance I wouldn't expect the sustained turns to be improved.  

 

Haven't tried the P-38 ingame yet so can't say wether it's overperforming or not, but if it's outturning the single engined types then I'd argue there's an error in the FM, esp. if it manages to do this without the use of flaps.

I wouldn't say the P-38 is overperforming, based off what I've read it's performing close to what I expected it to. It turns well with and without flaps and has a tighter turn radius than both the P-47 and P-51 just as it did irl. It can outturn a 190 pretty well and can stick with and even outturn 109s.

 

Climb is very nice and it has little trouble sticking with 109s in a tight slow spiral climb justs like the German accounts state.

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Sorry I'm not too familiar with P-38, but what is that "boosted roll rate" of 120 deg/s I see on performance document? Can you achieve this in-game? Do you need to use some key for that? I've flown only couple of sorties with Lightning, but I cannot recall it would have had rolled that quickly.

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9 minutes ago, Hanu said:

Sorry I'm not too familiar with P-38, but what is that "boosted roll rate" of 120 deg/s I see on performance document? Can you achieve this in-game? Do you need to use some key for that? I've flown only couple of sorties with Lightning, but I cannot recall it would have had rolled that quickly.

You really only notice the boosted ailerons when at higher speeds. At high speeds the only thing that can outroll the P-38 is the 190 and even then it's pretty close imo. When slow the 38 rolls poorly or average so it's best to try and stay fast when doing any type of rolling maneuver.

Booted ailerons are default, all you need is to go fast, try diving and then do a roll at around 300-400 mph, you'll notice a significant difference in roll rate compared to slower speeds.

Edited by Legioneod
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6 hours ago, Legioneod said:

I wouldn't say the P-38 is overperforming, based off what I've read it's performing close to what I expected it to. It turns well with and without flaps and has a tighter turn radius than both the P-47 and P-51 just as it did irl. It can outturn a 190 pretty well and can stick with and even outturn 109s.

 

Climb is very nice and it has little trouble sticking with 109s in a tight slow spiral climb justs like the German accounts state.

 

If it's outturning those aircraft then IMO it is overperforming quite significantly, esp. if its without flaps, as I don't see how it is to overcome its much less favorable wing & power loading to achieve it.  

 

IIRC the opinion of German pilots was also that it was the easiest of the Allied fighters to deal with.

 

 

 

Edited by Panthera

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20 hours ago, Panthera said:

 

If it's outturning those aircraft then IMO it is overperforming quite significantly, esp. if its without flaps, as I don't see how it is to overcome its much less favorable wing & power loading to achieve it.  

 

IIRC the opinion of German pilots was also that it was the easiest of the Allied fighters to deal with.

 

 

 

It has a tighter turn radius than the P-51, P-47, and Fw-190 just like it does irl. It has trouble with the 109 depending on the situation, I got in a fight yesterday with a good 109 pilot and I could not get lead on him at all he kept hit turn much better than me. I've also had situations where I turned with 109s and got them down rather easily, it all just depends on the situation and skill of the pilot.

 

I don't think the P-38 can outturn the 109 but it can stick with it for the most part with flaps. The 38 can certainly outturn the P-47, P-51, and Fw-190, even without flaps at least from my experience.

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9 hours ago, Legioneod said:

It has a tighter turn radius than the P-51, P-47, and Fw-190 just like it does irl. It has trouble with the 109 depending on the situation, I got in a fight yesterday with a good 109 pilot and I could not get lead on him at all he kept hit turn much better than me. I've also had situations where I turned with 109s and got them down rather easily, it all just depends on the situation and skill of the pilot.

 

I don't think the P-38 can outturn the 109 but it can stick with it for the most part with flaps. The 38 can certainly outturn the P-47, P-51, and Fw-190, even without flaps at least from my experience.

 

Yeah that's the problem, I really don't see how it should be able to do this considering its major disadvantages compared with the other aircraft mentioned in terms of wing loading, size & therefore drag comared with power required. All the P-38 has is a decent power to weight ratio, but it only has a small advantage here over the P-51 & P-47, and not enough to offset the big disadvantage in the other areas.

 

In terms of aerofoil the P-38 uses the same 230xx series as the Fw190, F6F & F4U, a good high lift airfoil, but not one which would give it anywhere near the Clmax needed to compensate for the huge disparity in wing loading.

 

Hence if what you say about how the aircraft is currently stacking up in IL2 is true, then IMHO there is a big error in the flight modeling. 

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The P-38 has a very high aspect ratio wing in relation to other WW2 fighters. It's 8.25 compared to the around 6 typically found on other fighters, so it has a large wingspan for the wing area it offers. This helps with achieving higher lift coefficients and therefore tighter turning radii. Not a huge effect, though. However, where we have a huge effect is with very important lift induced drag. It's inversely proportional to the span². So the difference between the P-38 and say the similar size P-47 wing (327.5 vs. 300 sq.ft.) is 60% more induced drag for the P-47 because of the lower wingspan (52 vs. 40.75 ft.). The relatively low drag of the P-38 is of course hugely beneficial in low speed turns, improving turn rate.

 

Now this massively reduced drag doesn't allow the P-38 to turn tight, but extended manoeuvre flaps provided sufficient lift and owing to a low drag to start with, the P-38 can compensate the extra drag. So what we should see, and as it historially was, is mediocre (but not poor) turning radius and performance without the flaps, and good turning radius and performance with the manoeuvre flaps set.

 

Additionally, the twin engine configuration with the counter rotating props gives a fairly smooth stalling behaviour, so pilots can more confidently approach the limit than they can in other fighters.

Edited by JtD
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The P-38 has had excellent turn performance as JTD described (mediocre without flaps and good with) in every sim that has modeled it except il2-46 which was generally horrible anyway. There are also numerous tests and anecdotes that support the claim of its agility in addition to the aerodynamic findings of modelers over the last 20 years of flight sims. There are anecdotes of P-38s turning with spitfires, and virtually every US test review of the plane claimed it was the best turning plane they tested. Robin Olds has said explicitly that down low he could out turn anything in a 38.

 

This is exactly as it performs in game. Its turn rate without flaps is OK. Once you get down to low speeds and the flaps come out, it will out turn anything in the game except the spitfire (with 100% fowler flaps deployed).

   

The P-38 only had a bad reputation for agility in some anecdotes because it was the only modern plane the USA had at the beginning of the war and it it was the plane the USA learned on.

 

Edited by YIPPEE

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On 10/22/2019 at 12:45 PM, Panthera said:

[...]

IIRC the opinion of German pilots was also that it was the easiest of the Allied fighters to deal with.

 

Do not forget the impact of the ergonomic issues Rau brought up in his assessment of the P-38 vs new pilot. 

 

If the pilot is lost in the cockpit during the critical point, it does not matter how good the plane is.

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On 10/24/2019 at 6:19 AM, JtD said:

The P-38 has a very high aspect ratio wing in relation to other WW2 fighters. It's 8.25 compared to the around 6 typically found on other fighters, so it has a large wingspan for the wing area it offers. This helps with achieving higher lift coefficients and therefore tighter turning radii. Not a huge effect, though. However, where we have a huge effect is with very important lift induced drag. It's inversely proportional to the span². So the difference between the P-38 and say the similar size P-47 wing (327.5 vs. 300 sq.ft.) is 60% more induced drag for the P-47 because of the lower wingspan (52 vs. 40.75 ft.). The relatively low drag of the P-38 is of course hugely beneficial in low speed turns, improving turn rate.

 

Now this massively reduced drag doesn't allow the P-38 to turn tight, but extended manoeuvre flaps provided sufficient lift and owing to a low drag to start with, the P-38 can compensate the extra drag. So what we should see, and as it historially was, is mediocre (but not poor) turning radius and performance without the flaps, and good turning radius and performance with the manoeuvre flaps set.

 

Additionally, the twin engine configuration with the counter rotating props gives a fairly smooth stalling behaviour, so pilots can more confidently approach the limit than they can in other fighters.

 

Whilst it's true that the high AR helps, we must remember the big size difference between these aircraft on top and the extra Cl and thus drag the P-38 is experiencing in order to conduct the same turn due to its higher WL.

 

But we can compare the AR of for example the Fw190 at 6.02 with the 8.22 of the P-38 and then calculate the Cdi using a Cl compensating for the difference in WL:

 

Cdi = (Cl^2) / (pi * AR * e)

 

P-38 Cdi = (1.118^2) / (pi * 8.25 * 0.8) = 0.060

Fw190 Cdi = (1.0^2)/(pi * 6.02 * 0.8) = 0.066  

 

So that's a 10% difference in Cdi at the same load factor, and this then ofcourse has to be multiplied with the wing reference area of both aircraft, in which case we get a figure about 1.65 times higher for the P-38, whilst the HP available is only ~1.45 higher if my reference numbers are correct (1490x2 / 2050x1). We ofcourse need actual thrust produced to be accurate, and to get a full picture of the drag we also need the Cdo for both aircraft. But with all that taken into consideration I see an advantage for the Fw190 here, even if it's small.

Edited by Panthera

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It would have been nice if you had posted the figures you used. Also, I tend to compare lift induced drag directly, saves me the lift coefficient and other things. In that case, it all boils down to lift²/span².

So going in with P-38 - Fw190

Weight: 7500kg - 4100kg

Span: 15.85m - 10.5m

lift²/span² ratio: 1.47 - 1

 

If both fly the same manoeuvre, i.e. pull the same g at the same speed, that's what the ratio of lift induced drag will be like. A 47% advantage for the Fw190.

 

I don't think 2050PS for the Fw190 is representative at all. Main reason for this would be that this is only achievable at sea level. If find figures around 1700 are more representative for a generalisation. Also 1 PS = 0.98hp, so that would leave us with 2000hp at best. But BMW gives only 1900PS for 1.65 ata anyway. The Allison at 60" boost, which is typical for a P-38J, gives you about 1600hp all the way from sea level to 8000m. 1490hp is the reduced take off setting at 54". Well, that said, comparing

 

2000hp vs. 3200hp gives the P-38 a 60% advantage in thrust, i.e. a ~5% thrust/induced drag advantage

1700hp vs. 3200hp gives the P-38 a 85% advantage in thrust, i.e. a ~25% thrust/induced drag advantage

 

Of course, there will be other factors that need to be considered, but I think that it shows that in particular in comparison to a Fw190A-8, the P-38 is competitive. Even at full load.

 

---

Induced drag is directly calculated from:

{\displaystyle D_{\text{i}}={\frac {L^{2}}{{\frac {1}{2}}\rho V^{2}\pi b^{2}}}},

Lots of things that aren't aircraft specific, only L² and b² (Lift and span) are. Where lift is weight * load factor, with load factor again not being aircraft specific. Allows to break it down to just weight²/span² - all other things in that formula will effect both planes to the same degree.

Edited by JtD

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I used 7940 kg for the P-38 and 4270 kg for the Fw190. 

 

AR is span^2 / wing reference area where I get 6.02 and 8.22 respectively. The Cdi is then calculated as described. 

 

The 2050 hp figure was a quick rounding down assuming 2100 ps, which upon looking uo the actual ratio of ps/hp is actually 2071 hp. And I'm ofcourse comparing the Fw190D9 here. 

 

Best I could find for the Allison was the 1490 hp, but we can take 1700 aswell in which case we get a ratio of 1.64 which is undoubtedly better than before but I'm still not seeing it beat the 190 round the turn. 

 

 

Edited by Panthera

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OK, if you take the D-9 1900-2000hp might be considered representative for low and medium altitude, in which case there's not much of a difference (L²/b² ratio 1.52, power ratio ~1.65), slight advantage still for the P-38.

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@JtD @Panthera I'll l admit I'm having trouble visualizing the curves, but do they have their peak turns at the same speed?

 

If the P-38 corner speed is significantly lower than the 190, if the 190 gets into a turn fight with it at the lower speed it could be losing turn rate at a considerablely greater rate than the P-38 and find itself on the back end of the curve. 

Edited by Voyager

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You can't, or at least shouldn't, translate these figures directly into turning performance. Parasitic drag is missing completely from the equasion. But, generally speaking, the above is relevant for the thrust limited side of the curve, i.e. medium speeds.

 

Owing to the higher wing loading of the P-38, the Fw190D would be able to fly the tighter turn and have the peak turn rate at the lower speed. This probably also means a higher turn rate. The Fw190D is also faster at low to medium altitude, so it would also be superior in the high speed part. Somewhere around the middle speed regions the P-38 would have some advantages. Something like this:

 

image.png.6f73f45ca4d34bf768f91a2bad10c765.png

 

Things change when the P-38 deploys flaps. Then I'd expect it to be superior or at least equal to the Fw190D in the low speed region, with a higher maximum turn rate at low speeds. Something like this:

 

image.png.685bbb1a2cf60d348074c4dd99a51517.png

 

Edited by JtD

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15 hours ago, JtD said:

OK, if you take the D-9 1900-2000hp might be considered representative for low and medium altitude, in which case there's not much of a difference (L²/b² ratio 1.52, power ratio ~1.65), slight advantage still for the P-38.

 

I guess it comes down to using different figures, I'm relying on the Jumo 213A performance charts which lists 2071 hp with MW50 at SL.

 

I we use 1600 hp for the P-38 then we get a 1.54 ratio difference in power, compared with the 1.65 ratio difference in thrust required using the 7940 kg & 4270 kg weights.

 

11 hours ago, JtD said:

You can't, or at least shouldn't, translate these figures directly into turning performance. Parasitic drag is missing completely from the equasion. But, generally speaking, the above is relevant for the thrust limited side of the curve, i.e. medium speeds.

 

Owing to the higher wing loading of the P-38, the Fw190D would be able to fly the tighter turn and have the peak turn rate at the lower speed. This probably also means a higher turn rate. The Fw190D is also faster at low to medium altitude, so it would also be superior in the high speed part. Somewhere around the middle speed regions the P-38 would have some advantages. Something like this:

 

image.png.6f73f45ca4d34bf768f91a2bad10c765.png

 

Things change when the P-38 deploys flaps. Then I'd expect it to be superior or at least equal to the Fw190D in the low speed region, with a higher maximum turn rate at low speeds. Something like this:

 

image.png.685bbb1a2cf60d348074c4dd99a51517.png

 

 

Let's not forget the Fw190 has flaps of its own :)

 

But yeah, using your own figures you're arriving at a similar result as myself.

Edited by Panthera

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41 minutes ago, Panthera said:

I guess it comes down to using different figures, I'm relying on the Jumo 213A performance charts which lists 2071 hp with MW50 at SL.

 

Yes, and only at sea level. It's 2000PS at 1500m and 1900PS at 4000m ad straight down from there on up. So using 2000hp is, I think, a fair average.

 

41 minutes ago, Panthera said:

I we use 1600 hp for the P-38 then we get a 1.54 ratio difference in power, compared with the 1.65 ratio difference in thrust required using the 7940 kg & 4270 kg weights.

 

But it's not 1.65. It's 1.52. I can arrive at the same drag coefficient relation you do, but (30.5 * 0.06) / (18.3 * 0.066) is 1.52 and not 1.65. Like I said, it's way easier to just go with weight²/span². :)

 

41 minutes ago, Panthera said:

Let's not forget the Fw190 has flaps of its own

 

Yes, it does, and a combat like setting will also be beneficial. But the Fowler flaps on the P-38 are both, more efficient and more effective. And they have a dedicated combat setting. It means that employing flaps, the P-38 will improve more than the Fw190 will.

 

Maybe like this:

image.png.1970e0fdc23ede5bb43f7f6bd7bfc109.png

 

Another thing to not forget is that at full load, the P-38 carries four times as much fuel as the Fw190, and consumption is not even twice as high. For equal endurance or range you could also use 7400kg vs. 4270kg.

 

Maybe like this:

image.png.0251ebb039cf165a17e402d997c4012b.png

 

 

Edited by JtD

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46 minutes ago, JtD said:

But it's not 1.65. It's 1.52. I can arrive at the same drag coefficient relation you do, but (30.5 * 0.06) / (18.3 * 0.066) is 1.52 and not 1.65. Like I said, it's way easier to just go with weight²/span². :)

 

Hmm so am I,  and I'm getting 1.52 as well, not sure where the 1.65 came from (?), must have misremembered the number. Also could've used weight^2/span^2 myself, but thought it best to explain the equation behind this. 

 

Anyway we've now roughly compared the Fw190 with the P-38 and seen that without flaps the P-38 shouldn't really be able to outturn it, esp. not with ease which is what I'm hearing people saying it's doing ingame. With flaps it should be able to rival the Fw190, P-47 & P-51 in the turn, but the 109 and esp. the Spitfire it is really nowhere near.

 

 

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55 minutes ago, Panthera said:

 

Hmm so am I,  and I'm getting 1.52 as well, not sure where the 1.65 came from (?), must have misremembered the number. Also could've used weight^2/span^2 myself, but thought it best to explain the equation behind this. 

 

Anyway we've now roughly compared the Fw190 with the P-38 and seen that without flaps the P-38 shouldn't really be able to outturn it, esp. not with ease which is what I'm hearing people saying it's doing ingame. With flaps it should be able to rival the Fw190, P-47 & P-51 in the turn, but the 109 and esp. the Spitfire it is really nowhere near.

 

 

Theres more to turning than just sustained turn rate, the P-38 has a decent instantaneous turn that can match most aircraft imo. I haven't played the P-38 all that much but with flaps I can stick with everything for the most part, this may not be a sustained turn but it gives me more than enough time to get guns on.

If I'm on a 109s 6 his turn wont help him escape. It doesn't matter if he has a better turn or not, I can still stick with him for 1 or 2 turns before starting to lose out, I can do the same thing in the P-47 even though we all know the P-47 had an average turn rate at best.

 

Turn rate isn't everything so I think we should do more testing of the aircraft before claiming that it's performing incorrectly.

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10 hours ago, Panthera said:

Anyway we've now roughly compared the Fw190 with the P-38 and seen that without flaps the P-38 shouldn't really be able to outturn it, esp. not with ease which is what I'm hearing people saying it's doing ingame.

 

You've been around long enough to know not to listen to what people say. ;) Test yourself.

 

Testing turn times at sea level I'm getting 21s for the Fw190, 20.3s for the P-38 both flaps up at about 300km/h, 22s and 20.7s both flaps down one position, at about 270 km/h. I tested the Fw190D-9 full fuel, the P-38 with 1200l, so about 4290kg vs. 7590kg. The P-38 does outturn the Fw190D-9, but it's far from easy.

I'm a bit surprised both aircraft go down to nearly the same turning/stall speeds. The P-38 needs an about 10% higher lift coefficient to do that. Maybe it's down to propwash, which is a larger factor for the P-38, so eventually no objections here.

Turn times flaps up are close, which I find OK, slight edge for the P-38 is possible.

Both lose time with flaps down, which I don't find OK. Edge for the P-38 is expected.

 

The reason why they lose performance appears to be unreasonably high drag related to the lowered flaps. From historical data I'd expect the flaps in start position on a Fw190 to cost about 50km/h in top speed, in game they cost 130km/h. Way too much. I recall this was already the case many years back, so it's probably a global issue.

Edited by JtD

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10 hours ago, Legioneod said:

Theres more to turning than just sustained turn rate, the P-38 has a decent instantaneous turn that can match most aircraft imo. I haven't played the P-38 all that much but with flaps I can stick with everything for the most part, this may not be a sustained turn but it gives me more than enough time to get guns on.

If I'm on a 109s 6 his turn wont help him escape. It doesn't matter if he has a better turn or not, I can still stick with him for 1 or 2 turns before starting to lose out, I can do the same thing in the P-47 even though we all know the P-47 had an average turn rate at best.

 

Turn rate isn't everything so I think we should do more testing of the aircraft before claiming that it's performing incorrectly.

 

Instantanous turn rate is where the P-38 loses out to the Fw190 however, due to the higher wing loading. (Both use the same airfoil)

 

As for the 109, the P-38 shouldn't really have a chance here, it's just way too far behind in lift/weight and thrust/drag.

 

Quote

You've been around long enough to know not to listen to what people say. ;) Test yourself.

 

Well the problem 1 is I am away from my main pc for the time being, and problem 2 is that I haven't found a way of properly testing it in IL2 as it lacks all the necessary gages, such as a G meter for example. 

 

1 hour ago, JtD said:

Testing turn times at sea level I'm getting 21s for the Fw190, 20.3s for the P-38 both flaps up at about 300km/h, 22s and 20.7s both flaps down one position, at about 270 km/h. I tested the Fw190D-9 full fuel, the P-38 with 1200l, so about 4290kg vs. 7590kg. The P-38 does outturn the Fw190D-9, but it's far from easy.

I'm a bit surprised both aircraft go down to nearly the same turning/stall speeds. The P-38 needs an about 10% higher lift coefficient to do that. Maybe it's down to propwash, which is a larger factor for the P-38, so eventually no objections here.

 

Well realistically the Fw190 should be the one turning slightly better flaps up,  so that's an issue IMO. Prop wash shouldn't really effect the P-38 any more than the Fw190, and the P-38 does suffer from have a larger part of its reference wing area taken up by engine nacelles + fuselage. That said the higher AR will actually increase the CLmax, but it won't be by 10% from 6 to 8.2. I believe it's usually around 7.5% from 6 to 9. So the Fw190 should realistically be able to go slower flaps up at the weights you listed. 

 

Again they should be close in terms of turning, but the overall advantage should go to the Fw190 all things considered. I don't expect the FMs to be final though either.

Edited by Panthera

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10 hours ago, Legioneod said:

If I'm on a 109s 6 his turn wont help him escape. It doesn't matter if he has a better turn or not, I can still stick with him for 1 or 2 turns before starting to lose out, I can do the same thing in the P-47 even though we all know the P-47 had an average turn rate at best.

 

Turn rate isn't everything so I think we should do more testing of the aircraft before claiming that it's performing incorrectly.

 

The P-47D in the game is still an ample turn fighter as long flaps are deployed over 50%. The major cons is that Jugs flaps are slow to open/close thus the enemy can disengage easily if noticed "the tactic".

 

The flaps in the P-38J are quick to open/close and the Lighting offers better acceleration thus it's not so easy to evade.

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P38 turns as it's described with maneavers flaps down. It's when you put down Full flaps that it becomes a monster, as it should. 

 

With full flaps and 50 Percent fuel, the p38 will out turn any equivalent loaded fighter except the spitfire 

Edited by YIPPEE

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12 hours ago, Panthera said:

Prop wash shouldn't really effect the P-38 any more than the Fw190

 

It absolutely should, both by span/area effected and by power going into it. FWIW, the lift coefficients for both planes were in excess of what I get in a power off stall, so prop wash definitely plays a role.

 

12 hours ago, Panthera said:

the overall advantage should go to the Fw190 all things considered

 

I disagree. All I need to do for the P-38 to achieve the relative performances I tested in game in clean condtion is to give it a 9% higher lift coefficient than the Fw190. That's well within the realms of possible, for several reasons mentioned above, and that means the overall advantage doesn't need to be with the Fw190D. In particular as I tested at sea level, which is the best possible altitude for the Fw.

 

12 hours ago, Panthera said:

I haven't found a way of properly testing it in IL2 as it lacks all the necessary gages

 

You pick the plane and fly it in circles, while keeping speed and altitude constant. Then you look at a watch. It doesn't really get more simple than that.

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