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Thread: P-39, Plus a what if

  1. #1
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    P-39, Plus a what if

    I'd like to start a thread asking about how to fly the 39N/Q generally against 1942-44 Germans.

    Also, what if P-39Q's were equiped with the VK-107 or AM-38? How much better would it perform? Would a VK-107/AM-38 even fit in the plane with the larger bore and stroke? Would the slightly heavier engine push the 39's center of gravity too far back?
    Last edited by Wilco_Niner; 23-04-2015 at 04:31.

  2. #2
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    The P-39 does a bunch of things well... but its quirky so you really have to get to know the plane before you can really use it to its best advantage.

    It turns very well (better than the 109s for sure), it has great firepower, decent visibility from the cockpit, and it dives and climbs decently. Its a poor altitude fighter so you want to keep it under 20,000 (or even 16,000 feet). Your best to use hit and run tactics against the Japanese but with the Germans you can certainly mix it up more. The danger is stalling this fighter. When it stalls all hell breaks loose and you need to fight to recover it if you can. Needless to say this is a bad combat situation to be in... generally its just bad but in combat its worse. So you can never really stall this plane. Focus on keeping your speed up and staying at a medium speed level (kind of like fighting in a Yak). Its a very streamlined fighter with a low drag coefficient so it retains energy well too so keep that in mind.

    Down low its a pretty hot performer in the 1942 range but by 1944 you'll start to see some disadvantages. Still it can mostly keep up in a fight so long as it doesn't have to run away or chase down the opposition. At some altitudes it can probably at least stay competitive.

    I will also say that spraying your target with guns is a bad idea in this plane. You have three different types of guns, with different ballistic arcs so aiming is a challenge. The .50cals in the nose should be your primary guns and then if you are on the mark with those then open up with the 37mm nose gun. The .30cals are generally useless but they can add a little extra weight of fire or physiologically weaken your opponents (its certainly a hail of bullets they spit out).

    As for speculative engine configurations... there's nothing really wrong with the Allison engine. It just needs a turbosupercharger to work well at high altitudes. It was eliminated from the P-39 design early on for a variety of reasons and thats primarily why the P-39 was never a solid USAAF fighter in the ways that they needed it to be.
    "I used to be Ice but it's just too cold outside so call me Shamrock and hope it's a lucky call sign."

  3. #3
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    Thanks for the advice!

    On the whole turbo thing, I think a turbo in the 39 would have been a terrible idea. First of all, the 38 took until 42-43 for them to finally get the turbos working; the 39 would never have been ready to fight until at least some time in 1942.
    Second, the turbo would have ruined the plane. The turbocharger in the P-47 was huge, and took up nearly half (if not more) of the rear fuselage. Without a bunch of ballast in the nose weighing the plane down, the 39's center of gravity would have been too far back.

    I really am interested in a P-39 built as a dedicated low/medium altitude interceptor. That's how it was most successful historically, as well. Remove the 7.62's in the wings, change the Brownings to UBs, replace the M4 cannon with an NS-37, change the engine to an AM-38 and I think the P-39 would have been awesome.

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    Quote Originally Posted by Wilco_Niner View Post
    Thanks for the advice!

    On the whole turbo thing, I think a turbo in the 39 would have been a terrible idea. First of all, the 38 took until 42-43 for them to finally get the turbos working; the 39 would never have been ready to fight until at least some time in 1942.
    Second, the turbo would have ruined the plane. The turbocharger in the P-47 was huge, and took up nearly half (if not more) of the rear fuselage. Without a bunch of ballast in the nose weighing the plane down, the 39's center of gravity would have been too far back.

    I really am interested in a P-39 built as a dedicated low/medium altitude interceptor. That's how it was most successful historically, as well. Remove the 7.62's in the wings, change the Brownings to UBs, replace the M4 cannon with an NS-37, change the engine to an AM-38 and I think the P-39 would have been awesome.

    It is and was awesome both in the game and in real life. The russians were incredibly successful with it since it was used in lower altitudes than what the americans did in the pacific.

    The P39 as was already said is an incredible turner, and if you know it well you can even feel confident about late war japanese zeros. It turns like a beast and in low speed fights with landing flaps you can keep it stable down to 180-190 kph and make a shot. It takes a bit of practice to be good with the 37mm and unless you are at close range, finding the shot for the 37 with MGs is rather difficult since they all have different muzzle velocity. I myself have countless hours on that plane, and im still not even close to 100% confident that i can catch it in a spin.

  5. #5
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    Quote Originally Posted by Wilco_Niner View Post
    Thanks for the advice!

    On the whole turbo thing, I think a turbo in the 39 would have been a terrible idea. First of all, the 38 took until 42-43 for them to finally get the turbos working; the 39 would never have been ready to fight until at least some time in 1942.
    Second, the turbo would have ruined the plane. The turbocharger in the P-47 was huge, and took up nearly half (if not more) of the rear fuselage. Without a bunch of ballast in the nose weighing the plane down, the 39's center of gravity would have been too far back.

    I really am interested in a P-39 built as a dedicated low/medium altitude interceptor. That's how it was most successful historically, as well. Remove the 7.62's in the wings, change the Brownings to UBs, replace the M4 cannon with an NS-37, change the engine to an AM-38 and I think the P-39 would have been awesome.
    Well at one point the USAAF wanted turbosupercharging in everything. That didn't quite work out for some of these so the P-39 shipped without it. Problematically it was a huge issue for the P-39 and P-40s over New Guinea during the Port Moresby campaign as they had to climb to 20,000 feet or more to intercept the Betty bombers coming over the Owen Stanley Mountain range. Performance was terrible, mechanics and pilots were ill equipped, and the USAAF lost all confidence in the type.

    But yes it worked great for the Russians. They appreciated the 37mm cannon, the cockpit glass was of exceptional quality compared to Russian cockpit glass, and the radio was both lightweight and extremely good quality (Russian types were not so much of either). Tactically they were all about the low altitude army support and so the P-39 served quite well there. Use it in that tactical fighter role and it'll be a great companion.

    BTW: The hottest of the P-39 models in game is actually the P-39D-2. For some reason its modelled with the hot rodded Allison engine making 1500 hp at fairly low altitudes so it has tremendous speed. Basically its what your theoretical (although probably mechanically impossible) AM-38 build would be like. The second best is the P-39Q-10 with the four bladed propeller, just the nose guns, etc.
    "I used to be Ice but it's just too cold outside so call me Shamrock and hope it's a lucky call sign."

  6. #6
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    I'm about to go on another fantasy turbo tech tangent here, so bear with me.

    The P-47, the only single engine US fighter that used a turbosupercharger, used a front-back model with the engine in the front, and the turbo in the mid fuselage behind the pilot. Now, if (and this is a huge if) you reversed the order, with the turbo in the front and the engine in the middle, the P-39 with a turbo could actually improve the plane's performance with the center of gravity shift. Of course this theoretical layout likely poses too many problems to actually be made and the first two really nasty ones that come to mind are:
    - Removal of the 37mm to make space for the turbo; making the P-39 far less useful as a point-defence bomber interceptor and strafing platform among other things.
    - And the real performance kicker; the area below the cockpit in the P-39 was already pretty tight space wise with the engine/propeller driveshaft, and making exhaust ducts for the turbo that were large enough to avoid causing an unacceptable amount of exhaust backpressure (and a corresponding loss in engine power) would likely necessitate the expansion of the area below the cockpit, screwing up the plane's aerodynamics.

  7. #7
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    Just so folks can see....

    The XP-39 I believe was the only P-39 to have the turbo supercharging gear installed. You can see the ducting behind the cockpit.

    "I used to be Ice but it's just too cold outside so call me Shamrock and hope it's a lucky call sign."

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    This might be interesting to your conversation. There was a later model p-39 called a p-63 king cobra. Same design but 1,800 HP and 410 mph with a bigger engine. Most if not all went to the Soviet Union. You can read a little about it here. Thanks for listening.

    http://en.m.wikipedia.org/wiki/Bell_P-63_Kingcobra

    Yea I always loved the door on this fighter, it appears to have a crank up window just like a car did.

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    The P39 was the last kit model I ever made I think
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  10. #10
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    Quote Originally Posted by James m View Post
    This might be interesting to your conversation. There was a later model p-39 called a p-63 king cobra. Same design but 1,800 HP and 410 mph with a bigger engine. Most if not all went to the Soviet Union. You can read a little about it here. Thanks for listening.

    http://en.m.wikipedia.org/wiki/Bell_P-63_Kingcobra

    Yea I always loved the door on this fighter, it appears to have a crank up window just like a car did.
    P-63C is quite the performer in IL-2 1946. Still doesn't have the altitude performance but as a tactical fighter its fantastic!
    "I used to be Ice but it's just too cold outside so call me Shamrock and hope it's a lucky call sign."

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