P39-L1 Kobra performance and discussion

[Danziger]

The gun pods were only on early MiG-3. The MiG-3 UD (our improved version) did away with gun pods. Even on earlier aircraft the pods were often empty or removed because the pilots didn't like the performance drawbacks of heavy wing guns. They also said firing the gun pods caused a lot of shaking and movement in the wings. With the gun pods gone they were forced to put bigger guns in the nose. Any of the two-gun nose armaments combined with wing pods aren't very historical. That's why I'd like to have our MiG-3 a dedicated late version and maybe get the early version as a collector plane later.

[Farky]

Performance chart of engine in P-39L-1 -

 

[216th_Lucas_From_Hell]

Each series only got 100 aircraft indeed as a rule, but the MiG-3 remained largely unchanged safe for armament after around July 1941. But I get the point being made, even if personally it won't make a difference - I'm taking the 37mm to town regardless 

[Danziger]

I think what they are trying to do with these modifications is cover more than one type of aircraft without having to make separate models. As an example the MiG-3 we have covers three planes in the Il-2 46 lineup.

[ShamrockOneFive]

We have a MiG-3 series 24, no more than 100 of which were produced. You don't put 'more than 200' of several different weapon layouts into 100 planes - which I think is the point SuperEntendard is making. In general, the armament options for the aircraft are a little bit generous. Which is why I'd expect the 20mm gun in the P-39L as an option, even though the manual only lists the 37mm gun.

 

I'd be ok with that. The default should definitely be the 37mm... but toss a Hispano 20mm in there with the 60 round drum as a modification. It was certainly a technical possibility.

[Irgendjemand]

I'd throw that 37 mm away and stuck in there Hispano, even though pilots complained about magazine with only 60 rounds it still sounds like a better option for dogfights. Even hunting bombers with that 37 mm wont be easy, unless one hangs on bomber tail ...

I always find it easier to hit a bomber from straight above rather than dead six. Much bigger target this way. There has been lots of times that i peppered all my ammo from dead six not hitting much.

Defelctionshooting is way easier in my opinion.

Edited September 13, 2016 by Irgendjemand

[LukeFF]

I ask because the lagg 37 rate of fire is so bad the gun is only useful against slow moving bombers.

Well, that is what it was designed for, after all (as fitted to the LaGG-3).

Edited September 13, 2016 by LukeFF

[SvAF/F19_Klunk]

This is kind of cool as well

 

[VBF-12_Snake9]

Well, that is what it was designed for, after all (as fitted to the LaGG-3).

And yet the p39 is worst. That's what I'm getting at. Dogfighting with the 39 I would rather remove the 37 altogether and just use the mguns. The 37 and that rate of fire is useless.

 

Nobody. . . (Nobody with any sense) dogfights with the lagg 37mm.

 

 

In 46 others and I used to place the 37mm at 1000 meter convergence just so you could hit something with it, but leave the mguns at normal convergence. Going to be interesting to see how it will work in this game.

[216th_Lucas_From_Hell]

No biggie, fire them all at once, shoot at close range and you're good to go. Still do it in 1946, and with the same convergence on both. The trick is getting used to it, because once you do enemy aircraft start falling apart like LEGO.

[ShamrockOneFive]

And yet the p39 is worst. That's what I'm getting at. Dogfighting with the 39 I would rather remove the 37 altogether and just use the mguns. The 37 and that rate of fire is useless.

 

Nobody. . . (Nobody with any sense) dogfights with the lagg 37mm.

 

 

In 46 others and I used to place the 37mm at 1000 meter convergence just so you could hit something with it, but leave the mguns at normal convergence. Going to be interesting to see how it will work in this game.

 

So... the 37mm is partially what the P-39 was designed around. So its very much integral to the fighter and it in part dictated its unusual design.

 

A P-39 specialist will get the most out of the cannon. And really, the fire rate of a 37mm at these low rates of fire is lower on the list of things that matter.

 

The technique is to use the machine guns to get your aim and when you're close enough or in the best position to fire, you tap the cannon and let off 1-3 bursts from the cannon. I'd advocate towards a single shot rather than holding the trigger. This is more of a sniper weapon than the kind of weapon where you walk your bullets across your targets path.

 

What the P-39 has that the LaGG does not is a more substantial set of machine guns to back it up. So the twin .50cals are pretty good on their own and the .30cals on the wings are probably overkill but they do add to the weight of fire. The Russian pilots remarked that the aircraft was good, the radio was excellent (above and beyond Russian sets) and the 37mm cannon had superb firepower. It was very much on the desirable trait list.

 

Unlike a 20mm cannon or a heavy machine gun... a single 37mm hit will be all that it takes to eliminate a fighter and bombers can't take more than 3-4 well placed hits.

 

If its weapon setup is not what you're looking for in a fighter... we're going to have a very lovely Yak-7B with some pretty serious firepower of its own. More of the rapid fire type.

 

The devs may still yet give us the Hispano 20mm as a modification. Will be interesting to see!

Edited September 13, 2016 by ShamrockOneFive

[216th_Lucas_From_Hell]

Back in the old Il-2 my favourite hobby with the M4 was nailing Bf-109s and Fw-190s trying to climb away. In those 1-2 seconds when they are well within firing range when repositioning for an attack, you could easily point the nose at them and let it fly. Usually the 37mm hit them and their plane was toast, but if not then a fierce machine gun salvo peppered them through and through.

 

The P-39 is far too perfect for its own good 

[VBF-12_Snake9]

Just trying to compare it to the closest thing we know and have right now. I'll probably pick it up on sale about two years from now.

 

P.s.

Thanks for teaching me how to aim and fire a cannon round.

[Tag777]

It's basically a P-39D-2 with a different propeller. You can expect it to at low altitude fly circles around every plane we currently have in game while being as fast as the Fw190A-5. 250 were built.

Yeah. I hope the engine response will be as indicated in the charts.

I always thought that the Russians did some modifications that were maintained in secrecy until today. For example, Pokryshkin stated that the performance of the Kobras were superior that p-40 at high altitudes (above 19,000 feet), that contrast with the knowledge we have about the airplane, that is its poor performance at high level (although, the p-40 performance was poor, also). Some mentioned that they replaced the Allison engine with the Klimov engine used by the Yaks, and exchange the 37 mm cannon with the Russian NS-37, but I did not find any reliable source to confirm this.

[Thad]

That's exactly what i wanted to say yes. Not terrible, like the P40 (god forbid), but also not rapid like the Yaks. Anyway, much looking forward to it

I'm disappointed. Was the P 40 FM actually that bad in real life in WWII?

[Scojo]

Did the P-39 discharge spent shell casings?

[von-Luck]

P40© is even less powerful with pretty similar weight, and Bf109F (19s turn time) pilots have been told to never engage a horizontal turnfight with them. There's surely a lot more to turn rate, then the 4 figures you were just giving

If i had to guess, i'd say the weight distribution within the aircraft also can make quite a difference

Here is a fantastic video which outlines the principle mechanics at work when considering aircraft turn rates.

 

https://youtu.be/etkqsaYP-nk

 

von Luck

[JtD]

Did the P-39 discharge spent shell casings?

For the nose guns they were collected in compartments, for the wing guns they were just dropped.

[Scojo]

For the nose guns they were collected in compartments, for the wing guns they were just dropped.

And would that have prevented the tumbling and spins people were talking about earlier in the thread?

[von-Luck]

And would that have prevented the tumbling and spins people were talking about earlier in the thread?

Hold a round in your hand. Now hold a spent casing. One of these weighs considerably more than the other. My immediate assumption would be no.

 

When you look at the 37mm M54 you can see where the majority of the mass is.

 

https://upload.wikimedia.org/wikipedia/commons/7/7d/M54_round_drawing.jpg

 

von Luck

Edited April 20, 2017 by von-Luck

[Scojo]

Hold a round in your hand. Now hold a spent casing. One of these weighs considerably more than the other. My immediate assumption would be no.

 

von Luck

Obviously it would be more prone to a spin or flip with lower weight, but I was speaking in reference to the first page of this thread where people mentioned Russian pilots of the P-39 said it was extremely easy to do and then the testing later found this only happened with no ammunition in the planes.

 

I just wanted clarification on whether that means that the shell casings help stifle that tendency at all.

In other words, prevented was the wrong word to use. My apologies

[von-Luck]

I imagine the shell casings help ever so slightly keep the center of mass a tiny bit further forward. But if the Soviets tested this empty I cannot imagine the additional weight of the casings is going to dramatically change the outcome. Purely my speculation though.

 

von Luck

[Scojo]

I imagine the shell casings help ever so slightly keep the center of mass a tiny bit further forward. But if the Soviets tested this empty I cannot imagine the additional weight of the casings is going to dramatically change the outcome. Purely my speculation though.

 

von Luck

Bell tested it, according to earlier posts, not the Russians.

 

But the assumption that empty casings wouldn't help is exactly why I was asking. I wanted to know if they did have any effect. They said the testing was only done empty, not with spent shells weight added to empty.

[Tag777]

I do not really found a source that could explain if the shell casings helps or not (I can assume probably helps. How much? Hard to say without an appropriate data available). Regarding maneuverability against German planes, Pokryshkin stated that German pilots never went in turns fights against the Kobras, so she would have and advantage in that aspect, even considering the high turn angles. What is clear is that the Russians tested thoroughly the plane and compensate it faults with a careful pilot training.

Edited April 20, 2017 by Tag777

[von-Luck]

I doubt that information is going to be easy to come by. Some "quick" calculations are somewhat surprising.

 

37mm M54 round weighs 1.99 pounds.

X 30 = 59.7 pounds fully loaded.

 

Empty cartridge is 0.49 pounds

X 30 = 14.7 pounds spent full load.

 

M2 50 cal BMG is 103.5 pounds for all 400 rounds (excluding links)

49.15 pounds for 400 spent casings.

 

Total ammo load full is 163.2 pounds vs 63.85 pounds spent.

 

So about a 100 pound difference give or take.

 

 

von Luck

Edited April 20, 2017 by von-Luck

[Scojo]

I can assume probably helps. How much? Hard to say without an appropriate data available

This.

 

I was just wondering if anyone had any more info, or knew if when Bell said "empty" it meant truly empty or a "combat empty" state since there was no mention that they did tests at weights in between the two states.

I have until November to figure out how to combat boom n' zoom with a plane that has it's best performance down low. I'm still really bad at it.

[6./ZG26_Klaus_Mann]

The unwillingness of German Pilots to turn with some Aircraft doesn't necessarily indicate Superiority, and most likely means that no Significant Advantage can be gained by Turning. If you only have a 70% or less Chance to win a Fight by turning when better options are available you don't turn. 

[A_radek]

I have until November to figure out how to combat boom n' zoom with a plane that has it's best performance down low. I'm still really bad at it.

Scojo. I suspect the boom n zooming crown will still belong to the fw and 109 for their top speed and climb rate. (Though the 39 does have an interestingly high max dive speed according to manual.)

 

The 39's strength will be it's armament and tactics that allows. Flying alone it won't do you much good. But with a wingman or several, a 109 on a 39's tail won't have much time to score some hits before receiving a very large shell. That coupled with a not so big performance difference..