P-39-style fighter by other people?

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tomo pauk said:
Soviets - they might want to install three Shvaks initially? A more powerful engine than the M-105 will be needed, so the Mikulin's V12s get used.
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Actually, the Gu-1 had a Mikulin engine (AM-37, more precisely, its geared version AM-41), but it was not mass-produced. It can be safely excluded from the list - as well as low-altitude AM-38 and -42, no one will allow to take away production facilities or finished engines from the mass series IL-2/-10.
Mikulin engines were heavy, none of high-altitude engines developed in Minulin's design bureau were brought to an acceptable condition by 1946.
After the extremely unsuccessful attempt with the Gu-1, the Soviets had zero interest in building their own fighters based on the Cobra scheme.
 
The P-39 had its radiators in the wings, very much like a Mosquito. They were way faster than an A6M at low altitude, so the airframe was pretty good. Why did they lose the turbocharger?

A disadvantage of placing the engine in the middle of the aircraft is that you want your consumables like fuel, ammunition, and paratroopers placed close to the centre of mass. The Spitfire's fuel tanks are a near optimal installation,. as long as the pilot does not mind being burned when they catch fire.

For a mid-engined aircraft, the gas tanks can be in the wing roots. The radiators can be anywhere out on the wings. If the wings are laminar flow, they can be fairly thick, like those of the Mustangs.

A radial engine does not work for me. You want those at the front of the aircraft where there is airflow. A Merlin or Griffin with a two-stage supercharger sounds like a better idea. You really want something awesome shooting through the propeller boss. 40mm Vickers? An MK103?
 
There is no point in building P-39 like aircraft. If you need to shoot through propeller hub, you can put gun between cylinder blocks, with ammo stored in the centre of gravity. P-39 layout was obviously horrible idea and that's why there were very few aircrafts in this configuration. In the Bell's case it was "innovativeness" forced by management.
The bigger the central gun, the better classic solution is.
Howard Gibson said:
For a mid-engined aircraft, the gas tanks can be in the wing roots. The radiators can be anywhere out on the wings.
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The only sane solution is in the tail, Mustang styled. Additionally one can armor it and engine using the same plate.
 
peceed said:
The only sane solution is in the tail, Mustang styled. Additionally one can armor it and engine using the same plate.
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No additional assemblies/armor plates/etc. could be placed behind the center of gravity of the Cobra anymore. Even small reinforcements of the after-fuselage required a counterweight in the nose section. The Soviets removed frequently the armor protection of the carburetor and the oil tank to avoid going into spin.
 
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List of the engines that, as-is, were not able to take a gun between the cylinder blocks
- V-1710
- Merlin
- Griffon
- Sabre
- Mikulin's V12s
Then we have the long list of the 2-row radials that also didn't allow the motor-cannon installation.

The bigger the central gun, there chance for it to be installed in the Vee of V12s was smaller as a retrofit on a fighter. Even when engines were designed to receive the motor cannon. See the German problems with installing the MK 101 and 103 in that position.

peceed said:
The only sane solution is in the tail, Mustang styled. Additionally one can armor it and engine using the same plate.
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Mustang's fuelage tank was not in the tail, but in, well, fuselage.
As noted by the fellow member, addition (or subtraction) of a substantial weight close to the tail (too that much away from the CoG) will make aircraft dangerously unstable, if even flyable if I might add.
 
tomo pauk said:
List of the engines that, as-is, were not able to take a gun between the cylinder blocks
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You need only one that was, and V-1710 is an ideal candidate for adaptation due to its modularity.
tomo pauk said:
Mustang's fuelage tank was not in the tail, but in, well, fuselage.
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So I was obviously talking about coolers, where "tail" means aft section behind engine.
Still easier than in P-39 style, considering CoG issues for ammo, and you have luxury of building brand new aircraft. BTW. Me-109 got its MK-108, only MK-101 was impossible.
Howard Gibson said:
You really want something awesome shooting through the propeller boss. 40mm Vickers? An MK103?
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37x145mmR has exactly same proportions as 30x113mm, so 37x145 with Minengeschoss ammo should have very satisfying properties for air combat - 400 gram shell with 100 gram HE filling having velocity 750 mps.
Scaled up MK 108 to 37 mm (its ammo has dimensions of 30x113, just little shorter projectile and longer case) could have rpm around 530 (690 for MK108A) and 125 kg of weight (higher than 109 kg from proportions, but we need longer barrel). Approximately an equivalent for 4 20 mm guns.
 
peceed said:
You need only one that was, and V-1710 is an ideal candidate for adaptation due to its modularity.
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Unfortunately, the modularity was applied for some of the things outside of the engine itself, like the detachable/remote reduction gear. It is the internals of the engine that will need reshuffling so the motor cannon can fit, as well as the ancillaries that might go in the way.
Note that this topic is not USA-exclusive, nor V12-exclusive.

peceed said:
So I was obviously talking about coolers, where "tail" means aft section behind engine.
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Okay, roger that.

peceed said:
Still easier than in P-39 style, considering CoG issues for ammo, and you have luxury of building brand new aircraft. BTW. Me-109 got its MK-108, only MK-101 was impossible.
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The 108 was a far more compact gun, with shorter and lighter ammo, and with half of MV (that saw chance to hit from distances away from the defensive .50 fire being low). MK 108 weighted 60 kg, the 101 and 103 were at about 140. Point of this thread is to install more powerful guns than it was the case historically, so the MK 108 does not qualify.
The Messerschmitt concept for the MK 103-armed Bf 109 also 'deleted' the cowl MGs and their ammo so the weight and volume of the new cannon installation is less of an issue, while the P-39C flew with one 37mm gun, two cowl HMGs, and two cowl-mouted LMGs. So the P-39 style is still far easier.

The M4 gun with Mine shell certainly gets my vote, since it being lighter and thus faster makes the ballistics far better suitable to hit the 'fighter sized' targets during the normal combat maneuvers.
The scaled-up MK 108 is again a good call as far as the destructive power goes, where is less stellar is the muzzle velocity. It is/was important against the aircraft sporting good defensive firepower (B-17s as a typical target for the LW in 1943-45), as well against the fighters whose pilots are on the ball.
 
tomo pauk said:
The scaled-up MK 108 is again a good call as far as the destructive power goes, where is less stellar is the muzzle velocity.
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We can rescale MK-103 gun. 37x145mmR has similar mass to 30x184RB (in the range of used types). With shorter cartridges new gun should have higher rpm. comparable with rescaled MK108 target 530, shorter receiver and lighter barrel (muzzle energy 113 kJ instead of 145) should lower mass to our 125 kg target.
MK-108's selling point was extremely cheap construction, not absolute performance or ballistic efficiency.
 
125 kg is not our target.
When you say 'rescale', what exactly do you mean for the MK 103 derivative, as well as the MK 108 derivative?

I've been suggesting several times now that a gun, that is in-between the MK 101(or 103) and the Mk 108, would've been a good fit for the Bf 109. Weight ballpark of 100 kg, 500 rd/min, 700-650 m/s for the 300-330 g M-shell.
OTOH - a 37mm gun of size and weight of the MK 101/103 would've probably be also good for 700 m/s with a 500g M-shell*, and at ~400 rd/min. Probable advantage vs. the 30mm M-shells is that 2-3 will suffice to bring down a 4-mot, vs. five for the 30mm.

* the MK 103 was firing the 500g APHE shells at 725 m/s

peceed said:
MK-108's selling point was extremely cheap construction, not absolute performance or ballistic efficiency.
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Agreed.
The shell - when it hit - was still devastating. As a gun for night fighters, it was perhaps the best there was, even if it have had it's shortcomings as a 'day fighter' weapon in 1943-45.
MK 108 was also a lousy gun for tackling the armored targets like the AFVs and tanks.
 
The most successful rear-engined fighter of WW2 undoubtedly would have been the North American P-78, which would have been based on this RR proposal for mounting a Griffon engine in a P-51 airframe. Since the name Mustang was already taken by the P-51, I would recommend the name Bronco.

 
tomo pauk said:
When you say799 'rescale', what exactly do you mean for the MK 103 derivative, as well as the MK 108 derivative?
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Uniform scaling of MK108 and small adjustments to MK103 with different barrel, the most notable is receiver shortening that should increase rpm.
tomo pauk said:
I've been suggesting several times now that a gun, that is in-between the MK 101(or 103) and the Mk 108, would've been a good fit for the Bf 109. Weight ballpark of 100 kg, 500 rd/min, 700-650 m/s for the 300-330 g M-shell.
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For universal gun you need minimum 750 m/s, it was German requirement IIRC and muzzle velocity of MG 131 used in Me-109 (intentional de-Bf-isation).
I also had exactly the same idea - what about adjusting 30x90RB, to get more powder and shorter lighter shell, to use it in MK 108?
I carefully chosen diameters only to discover, that the final result is identical to 30x113, ammo originally used in DEFA and ADEN revolver cannons, MK 213 developments.
The most striking thing is that these shells have exactly the same momentum,
540m/s*330g = 178 kgm/s for German shell,
795m/s*220g is 175 kgm/s for Swedish HEI,
and same momentum is totally irrevelant for mechanics of revolver cannon, but the crucial for MK 108 action.
So I have very strong suspicion, that 30x113 is originally a German idea, created for MK 213 and MK 108 as common round.
(Mine had 240 grams and 750 m/s, 180 kgm/s).
MK 108A having 850 rpm is a very potent weapon with this cartridge, 70% higher rpm than your wish wish .
Such Me-109K with MK 108A and two MG 131 has higher firepower than four HS.404 Mk.V.
 
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peceed said:
Uniform scaling of MK108 and small adjustments to MK103 with different barrel, the most notable is receiver shortening that should increase rpm.
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Okay.

peceed said:
For universal gun you need minimum 750 m/s, it was German requirement IIRC and muzzle velocity of MG 131 used in Me-109 (intentional de-Bf-isation).
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The 100 kg gun should've been able to beat the 700 m/s. Many times, I try not to over-sell my 'products', and post the numbers on the conservative side (the conservative people will probably say 'on the safe side' )
The latest German gun projects, like the Mk 112 and the like were at about 600 m/s, while there was also a host of 900-1000 m/s guns; the 750 m/s guns are pretty much absent. The MG 131 was tested, necked down to 8 and 10mm, in order to increase MV in order to achieve the much greater armor penetration.

Installing the 50-55mm guns will also be far easier on the P-39-type of aircraft, than it will be the case on the 'classic' 1-engined fighters. Installing two 30mm - on firing through the prop, another as a synchronized gun at the 10 or 2 o'clock position - would've also worked on a P-39-like; it will require the positively locked action of the gun in order to be synchronized, though. Same with a good 37mm cannon in the prop position.


Make a 250-270 g shell, use 40 g of propellant instead of 30. Even having 36g means a 20% increase of the propellant weight. A bit longer barrel will also be needed, but that's not an issue with the 108. Benefit of such a gun is that chance to hit goes up, but the target effect goes down - so perhaps now it is 7-8 shells needed to kill a B-17 instead of 5?
(yes, increase of the RoF will be needed here to cater for the lower lethality of the single shell)

Japanese have had a similar gun, the IJN Type 2 cannon, where they traded the shell weight (as well as the RoF, apparently) for the MV. Their Type 5 was potentially the best 30mm of the war, firing a heavy shell at good MV and good RoF, all on the modest weight. However, as it is often with the best gear, it was too late to matter.

The DEFA/ADEN ammo from the 1970s is IMO also in the sweet spot of what would've been good for ww2 guns for air fighting.
 

The P-78 was the designation originally given for the P-51 re-engined with the Merlin.

The designation was changed to P-51B, and the P-78 designation not used for anything else.
 
peceed said:
You need only one that was, and V-1710 is an ideal candidate for adaptation due to its modularity.
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It is possible to modify most anything if you spend enough time and money. The quest is often should you.

I will note that the French HS engines(and Soviet) used a small supercharger and the Germans turned their superchargers 90 degrees to get them out of the way of the Vee mounted cannon.
You could modify the V-1710 to take a Vee mounted cannon (Vee mounted simply means the barrel is aligned with prop hub, not that the gun is actually bolted to the engine like the HS engines) But as noted by others, you need to rearrange the intake manifolds and move the supercharger out of it's existing area and relocate some of the accessories.
Also find room for the carburetor, Germans used fuel injection and while the pump was located in the Vee there was no large lump like a carb in the intake tract. HS used 6 small carbs on the outside of the engine.
Such a V-1710 would be very heavily modified and require a fair amount of time in development (supercharger drive may have to handle 150-200hp just for historic power levels of 1942/43) and introducing right angle drives (either side or below) adds complication. Not impossible, just more time and money.
 
peceed said:
So I was obviously talking about coolers, where "tail" means aft section behind engine.
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In aircraft parlance, "tail" refers to the empenage: vertical stabilizer (fin) and horizontal stabilizers.
The portion of fuselage behind the cockpit and ahead of the empenage (tail) is regerred to as the "after section" or rear fuselage.
 
bf109xxl said:
Why?
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Because it uses an advanced primer ignition blowback mechanism.
The momentum of the bolt should be exactly half of the momentum of the projectile (and propellant). Too small recoil and weapon can not cycle properly, too big and recoil spring can not to absorb all kinetic energy of the bolt.

tomo pauk said:
The DEFA/ADEN ammo from the 1970s is IMO also in the sweet spot of what would've been good for ww2 guns for air fighting.
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Both ADEN and DEFA entered service in 1954.
37x145mmR with 400g mass /100g the mineshell should have the same ballistic. 10 mm shorter shell gives a little more room for powder increasing muzzle velocity from 750 mps to 790.
What about licensing the supercharger from Daimler Benz? Looks like a double win for me!
Shortround6 said:
Also find room for the carburetor, Germans used fuel injection and while the pump was located in the Vee there was no large lump like a carb in the intake tract.
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The inlet can be placed on the same side as the shaft, like in 2-stage superchargers.
Carburateurs after supercharger are a big no because they can not use the cooling effect of the fuel evaporation.
 
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