P-39-style fighter by other people? (1 Viewer)

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tomo pauk

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Apr 3, 2008
Basically a fighter that has the engine behind the pilot so the space in the nose is devoted to the installation of the substantial guns' firepower; engine being connected to the tractor prop by the extension shaft. U/C can be a tricycle, but it is not mandatory. Of a modest size - talk something that is not bigger than a Spitfire, with a better-than-average cooling sytem layout for a lower drag, and a fully retractable and covered U/C. Wing is 15-ish % thick at root, and uses the airfoil that is in vogue at the respective design bureau.
If one feels adventurous, the engine of choice can be a radial, like it was the case with the Piaggio P.119, but also a big liquid-cooled engine in the 2000+ HP class, like the Sabre or the V-3420, however these will require a bigger airframe.

Countries of interest are UK (the future Class S was supposed to be an airborne gun to kill enemy fighters), Japan (so they - both IJA and IJN - can install powerful guns on an 1-engined fighter), USA (again, but this time with the better chance to succeed than the 50-series fighters or the P-75), Germany, Soviet union, indeed Italy etc.

Yes, I'm aware of the Me-509, and the Soviet and Japanese etc. attempts on creating the similar A/C.

Service use starts in 1941/42, or in 1943 at latest, all depending on the country, so the design phase needs to start several years earlier.
 
British Cobra:
- Merlin is as good choice as ever
- can do as a tail-dragger; the under-nose volume can be used for radiators instead of the housing for the nose U/C member
- with the 40mm in the nose, can be a good tank buster
- there is a lot of 'real estate' under the wings, as well as the weight allowance to carry bombs or rockets along the 40mm in the nose
- as a 'true' fighter, it can do well with three Hispanos, and still should be able to carry external payload
- British were rarely, if ever into the long range fighters, so 'surrendering' the CoG-neutral volume to the engine instead of using it for fuel tank(s) is not an issue
- if drag is kept under control (radiators, U/C etc.), with Merlin 45 it should've mimic the performance of the P-39N; the ground attacker can do well with low-level Merlins, while the later fighter it should do well with better Merlins
 
Basically there are a few little problems.
Bell figured that the drive shaft was about 50lbs and the stronger fuselage needed to keep the prop reduction gear in line with the engines, they allowed 1in (25mm?) of "flex" between the two. If you think the 100lb weight penalty is worth the drag reduction or other benefit, fine.
Fuel pretty much has to go in the wing. Not a problem until protected tanks come into play. Long skinny tanks are heavier than short fat tanks. Unless you use a fat fuselage and stick the tanks in the wing under the fuselage?
Engine may run a little hotter due to less airflow through the engine compartment. You can add intakes.
There is a problem mounting too much armament in the nose, The CG shift as the ammo is used, unless the guns/ammo are just in front of the cockpit and used blast tubes but that means some empty space in the nose.

The 40mm for a tank buster needs a 40mm cannon and only the British had one, and it was sort of a rushed, cobbled together lash up.
It was not the 2pdr AT gun or the 40mm Bofors gun.
It was better than the 20mm Hispano but it was not in the same class as the German 37mm gun used in the Ju-87 and Hs 129.
While useful against light armor, light armor could be taken out with 20mm Hispano guns.
 
Welcome back
P-39 managed to be lighter than the P-40, by some 400-500 lbs in the 'basic weight', despite all of that + the tricycle U/C.

Shortround6 said:
Fuel pretty much has to go in the wing. Not a problem until protected tanks come into play. Long skinny tanks are heavier than short fat tanks. Unless you use a fat fuselage and stick the tanks in the wing under the fuselage?
Click to expand...

Other people were not as ... stubborn as Bell, that managed to make 12 separate fuel tanks for the 120 US gal fuel load. See eg. Yaks and other Soviet aircraft, as well as NAA, whose designers didn't allow for the ribs to mess up with the fuel tankage.
But, at any rate, already 120 US gals is more than what the Spitfire or Bf 109E-K have had installed in 1941-43, and drop tanks are still a thing.

Shortround6 said:
here is a problem mounting too much armament in the nose, The CG shift as the ammo is used, unless the guns/ammo are just in front of the cockpit and used blast tubes but that means some empty space in the nose.
Click to expand...
I'd say that the 'we don't have enough of space to install the firepower we desire' is a far bigger problem than 'we have a lot of elbow room' one


The 20mm gun will have a very hard time to take out a medium tank, like the Pz-III and -IV the British were dealing in Africa, Italy and France.

The Class S was with a no worse penetration than the 2pdr, with both using the 'normal' AP shot, that was 3 pdr heavy for the Class S vs. the 2pdr for the, well, 2pdr gun. Penetration with the 'Littlejohn' ammo was also in the ballpark; the Class S didn't used these in anger, though.
 
The Vickers S Gun as a fighter gun need not fire AT rounds and the OTL ones on Hurricanes were accurate with the HE round which was the most common ammunition used in Burma and a 40mm HE round will prove a power of no good on against any aeroplane in the sky. Some what long being a long recoil design and with a limited magazine but a belt feed will help. With a Littlejohn adaptor, AT round and the extra velocity from being fired from a 250mph+ starting point it could penetrate most tanks other than the frontal plates of the latest ones. Remember German tanks were being fitted with spaced sheet armour not to defeat shaped charges but to tumble anti tank rifle rounds which could penetrate even Panthers from the side. Its real shortfall in air combat is the rate of fire. A cumbersome beast to tuck in between the pilot and the propellor though.
 
We do have to be a bit careful with the Class S gun. Some of the penetration tables are adding 107m/s a second for the speed of the plane. A lot of the German and Soviet tables are not. That assumes that the armor is the same. Also assumes that projectiles are of high quality.
The 2pdr AT gun was one of the weapons the British screwed up the most with cheap ammo. The HE ammo didn't really show up until 1943 and the APCBC shot didn't show up until 1943. They had been making APCDC shot for naval guns in WW I, it was not new in 1939. It cost more.
Well, Yak and NAA had not planed to simply seal up the wing skins and use the space for fuel tanks with the ribs still in place. NAA always planed to have a large tank in the space with the structure going around it, not through it. If you spend enough time you can beef up the main spar. Beef up the leading edge/ forward spar and the wing skins so you can cut out the ribs and drop down to 2-3 tanks in each wing instead of 6. Is it worth it?
tomo pauk said:
P-39 managed to be lighter than the P-40, by some 400-500 lbs in the 'basic weight', despite all of that + the tricycle U/C.
Click to expand...
Well, you could eventually hang 2500lbs of bombs under a P-40, you couldn't do that with any P-39
The P-40E gained 682lbs of empty weight over the P-40 no letter. 291lbs of airframe, 238lbs of powerplant and 153 lbs of fixed equipment. Guns are not included.
Trying to compare different airplanes even with the same basic engine to figure out "trick" features leaves a lot of things unaccounted for.
 
If the goal is to free up the nose for armament and ammunition while keeping to a single engine, we're going to be hard pressed to reject a rear-engined pusher prop in favour of the P-39's complicated linkage and volume-consuming nose prop layout.
 
Admiral Beez said:
If the goal is to free up the nose for armament and ammunition while keeping to a single engine, we're going to be hard pressed to reject a rear-engined pusher prop in favour of the P-39's complicated linkage and volume-consuming nose prop layout.
Click to expand...
Except you still need an extension shaft, and a way to locate the prop in relation to the engine. If you put the reduction gear on the engine the prop shaft turns slower but it needs to handle more torque.
Granted you don't need to fire guns out through the prop disc.
 
Run a drive system that transmits power from the central engine to two counter-rotating props mounted on the wing.

Move the pilot forward and mount the guns under the fuselage, to either side of the nose gear.

Might allow for installing an even bigger gun for ground attack.
 
tomo pauk said:
engine being connected to the tractor prop by the extension shaft.
Click to expand...

SaparotRob said:
Being a coward, I wonder about the efficacy of bailing out of a pusher prop plane.
Click to expand...

Not a worry in this thread


Yes, the penetration is somewhat helped by the speed of the flying aircraft. The 50% heavier AP shot vs. what the 2pdr had also helped out; yes, a better AP shot would've been handy. HE shell is not as needed in this case since there is enough of place for bombs/rockets under the wings.


The designers will be doing bespoke design, so there is no need to use the warmed-up P-39 wing structure.

Now about the Germans.
Engine can be either the DB 601 or Jumo 211 for this time frame, and perhaps the Jumo 213 can fit in later since it was a more compact engine than the 211? At any rate, the prospective gun in the nose is probably the MK 101 (it was being tried out, back in 1940), with two synchronised MG 151 (the P-39C held the 37mm gun, two HMGs and two LMGs and the respective ammo, so this 1+2 cannons might just fit in). Switch to the MK 103 by mid-1943.
 
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.
Later, use the 37mm gun in the center position, while the UB HMGs replace the synchronized 20mm guns.
Hopefully it would've been luckier than the Gu-1 of the similar layout
 
When I see the arrangement used by Macchi M.C.72

I keep thinking...
How the hell did no one think of doing this with a DB-601 or a Merlin in a WWII fighter.
 
The Germans did (I think), but did not actually attempt any DB60x series inline tandems until later in the series.

I do not know if the US or UK made any serious attempt(s) at inline tandems, but they effectively had no reason to. The combination of operational requirements, sufficient supply of high quality fuels, excessive production capacity, and the timing of these factors, allowed them to escape any need for such a method until (maybe) toward the end of the war in the PTO. And at that point there was no over-riding reason to adopt the layout - it was easier just to put bigger engines in a conventional twin-engine airframe such as the F7F or the Hornet.
 
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