Better P-39

IMO improving the P-39 really centers around one of three things happening.

1) Sufficent turbo production to equip the P-39 with one. The plane was designed to use one and it never had the performance as a production model that the prototype did

2) Boost Merlin production at Packard enough to install in P-39s

3) The real wild card. The War Department gives Ford the go ahead to build the V-1650 which on paper looked to be as good and most likely better than the Merlin and cheaper to build too due to its replacing a lot of the expensive forgings with steel castings and the use of side by side rods instead of Fork and Blade. Ford was so confindent that the company ordered the tooling for production with out even getting a contract from the Air Corps. But all was not in vain as the engine with four cylinders removed became the GAA Tank Engine http://www.fordgaaengine.com/ One unusual feature of the XV-1650 was the studs on the Main Bearing Caps were splayed outwards at 30 degrees to vertical so that two studs carried the load for the right bank and two for the left bank.


A better wing would be an improvement but a new wing and some other stuff just gets you the P-63. It really centers around the powerplant.

Or better yet, Pratt and Whitney doesn't get cold feet and develops the x-1800 http://en.wikipedia.org/wiki/Pratt_%26_Whitney_X-1800 and Bell manages to shoehorn one into the airframe
 
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The P-39 is unfairly criticized because the western allies (who seem to think that WW2 in the air revolved around the Battle of Britain and their own strategic bombing campaign) did not have the best experience with the type. The only real fault of the P-39 (which was not due to its basic design but decisions made by Bell and the AAF) was the deletion of the supercharger. Even then, the Russians proved it to be an excellent low altitude fighter-bomber and ground attacker, and they also claimed it could handle both the Bf-109 and Fw-190 at low altitudes in the right hands

The reasons the P-39 gets criticized primarily lie in the fact that, at the altitudes the Luftwaffe, RAF and USAAF fought in western Europe, it was limited by the low altitude rating of its engine. In both the Russian front and in the Pacific, where engagements tended to be fought at lower altitudes, the P-39 was usually able to handle itself fairly well against most enemy fighters, once its pilots understood how to use it.
 
The P-39 is unfairly criticized because the western allies (who seem to think that WW2 in the air revolved around the Battle of Britain and their own strategic bombing campaign) did not have the best experience with the type. The only real fault of the P-39 (which was not due to its basic design but decisions made by Bell and the AAF) was the deletion of the supercharger. Even then, the Russians proved it to be an excellent low altitude fighter-bomber and ground attacker, and they also claimed it could handle both the Bf-109 and Fw-190 at low altitudes in the right hands

The reasons the P-39 gets criticized primarily lie in the fact that, at the altitudes the Luftwaffe, RAF and USAAF fought in western Europe, it was limited by the low altitude rating of its engine. In both the Russian front and in the Pacific, where engagements tended to be fought at lower altitudes, the P-39 was usually able to handle itself fairly well against most enemy fighters, once its pilots understood how to use it.

Very well put, Zoomar. I seriously doubt that the Cobra airframe would handle much more power without being a real handful. The post-war racers had the Kingcobra engine installed. These came equipped with a second stage supercharger, hydraulically driven, providing all the altitude performance previously lacking, but required the skill of a test pilot to control, or the revised airframe of the King, with enlarged tail and larger size. The Soviets had one edge over Western pilots, in that they totally ignored boost restrictions, at the expense of engine life. Good trade. One of the advantages of fighting close to the front was that you were never far from home. Perhaps less an option when you don't like swimming with sharks.
 
These posts have correctly identified why the P39 was unused in the west whilst popular on the eastern front. In the west the USAAF wanted fighters that could escort heavy bombers at altitude and the altitude performance of the P39 was not up to it. The Soviets wanted to escort medium bombers at low altitudes. This was where the P39 was at it's best.

Certainly the 20mm Hispano fitted, as the RAF used the P39 as such. Whether the US cock up version would work often enough is doubtful. Using Russian guns was not an option as this involved major industrial changes and a whole new ammunition production supply. CoG required something heavy in the front so x2 wing 20mm instead of the 37mm was not on.

A better pressure charging system would not make the P39 better for the major user. On the contrary the weight would impact upon range and load at the lower levels at which they wanted to use it.

To make the P39 perform at the altitudes wanted on the western fronts really needed a P63 in effect.

So my conclusion is that there would be little point to a better P39 in Europe.

In the Pacific I suspect that initial tactics were faulty and soon the production was demanded by the Soviets so there was no need to tailor the P39 for Pacific use and the give away is that the P40 was developed for continuing use there.

The best improvement would be an earlier P63 which was a Soviet low level warhorse post war in the Russian East.
 
...I just have a weakness for more nose guns.:p...

I've wondered what kind of plane we might have if instead of the central engine running a shaft forward to a conventionally placed single nose propeller, it ran the shaft sideways into the wings, to drive gearboxes that drive a pair of wing-mounted props. Because they don't have engines, and we have two props to do a job normally done by one, the prop area hence radius for each can be smaller, so the props can be closely coupled to the fuselage, while there would be little to no "nacelle" drag since the gearboxes can be quite compact, possibly buried completely in the wing. Also, if it helps, the props could be arranged as pusher props behind the wing instead of in front of it.

Then of course, the nose is available for a compact gun bus as on the P-38!

Also, I suggested on the P-38 thread running transmissions between the two engines on that plane, to allow for shutting down one engine and driving both props by the other, for greater range and endurance in long slow cruising.

Something that is totally not a P-38 nor a KingCobra, but perhaps an evolution, might be a two-engined version, twice the mass and area, with the two engines centrally mounted and the clutch arrangement to allow either each engine to separately drive a respective wing prop (I gather it's a bad idea to apply two IC engines to one joint load!) or for either one to drive both would be nestled between the engines.

I wonder how impractical it would be to replace the liquid-cooled engine with an aircooled radial. It means arranging a powerful fan and airflow in the engine compartment to keep it cool of course.

An advantage of the system of having a big radial stuck at the front of the plane as on many successful US designs like the Republic Thunderbolt and the Vought Corsair was, the radial engines could often keep functioning even when some of the cylinders were shot up. The engine served as forward armor for the pilot!:p

Obviously we forego that advantage with designs like either the P-39 or P-38.

Finally--no good suggestions for improving the balance of the fuel tanks, but could there have been a way to arrange the ammo so that there were two magazines, one ahead of the wing, one behind? As the guns fire, they feed into them in synchronization, so that the depletion of each matches and the CM is maintained. Obviously there is an awkward long chain from the one behind, and that has to run past some equipment that is both highly critical and runs hot--supercharger if any, and engine!:eek:

Could this have been done though?
 
Shevek23 said:
I've wondered what kind of plane we might have if instead of the central engine running a shaft forward to a conventionally placed single nose propeller, it ran the shaft sideways into the wings, to drive gearboxes that drive a pair of wing-mounted props. Because they don't have engines, and we have two props to do a job normally done by one, the prop area hence radius for each can be smaller, so the props can be closely coupled to the fuselage, while there would be little to no "nacelle" drag since the gearboxes can be quite compact, possibly buried completely in the wing. Also, if it helps, the props could be arranged as pusher props behind the wing instead of in front of it.
Why do it the hard way? Why not just take the twin boom arrangement & fit a pusher prop, like the J-21? Or delete the booms & go XB-42?
Shevek23 said:
two-engined version
Getting way, way outside "improved P-39" now.;) IIRC, the Sovs did something like it. Don't think "twice the mass and area" is essential: two in a row, cockpit in the extreme nose?
Shevek23 said:
I wonder how impractical it would be to replace the liquid-cooled engine with an aircooled radial. It means arranging a powerful fan and airflow in the engine compartment to keep it cool of course.
Sounds a bit odd, but "of course" IDK: why not an annular intake? Boundary layer (NACA scoop) preferably.
Shevek23 said:
two magazines, one ahead of the wing, one behind? As the guns fire, they feed into them in synchronization, so that the depletion of each matches and the CM is maintained.
I'm seeing more needless complication.... Not to mention more opportunities for jamming & battle damage: what happens when the ammo feed catches fire & you get cookoffs sending stray rounds into everything--with the feed running around fuel or cockpit?:eek: Bad enough when it's all in one place.

Might be better to fit some kind of automatic trim system, so as CG changes, trim tabs respond. Too sophisticated for the '40s?

As mentioned, what about moving the cockpit into the nose & the guns backward, firing out of the "shoulders" (cheeks, but nearer the CG)?
 
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Might be better to fit some kind of automatic trim system, so as CG changes, trim tabs respond. Too sophisticated for the '40s?

As mentioned, what about moving the cockpit into the nose & the guns backward, firing out of the "shoulders" (cheeks, but nearer the CG)?

Trim tabs aren't a solution. Aft CG shift means the airplane will mush, stall and enter a flat spin. It only happens if you want to go up or turn. The same characteristics plagued the P-51D when the extra fuel tank was installed behind the cockpit. It held 90 gallons, and climb rate had to be restricted until the tank was emptied. The solution was to be gentle, or only partially fill the tank. The P-51H tank only held 65 gallons. By the way, the "extra" tank on the Mustang held more fuel than the P-39 tanks total.



The TP-39 had no shoulders and would have required B-25-style gun blisters.

tp39c.jpg
 
Just Leo said:
Trim tabs aren't a solution. Aft CG shift means the airplane will mush, stall and enter a flat spin.
Yeah, I had a feeling trim tabs wouldn't have enough authority, even if the automatic system would work.
Just Leo said:
The P-51H tank only held 65 gallons. By the way, the "extra" tank on the Mustang held more fuel than the P-39 tanks total.
IDK that. Thx.:)
Just Leo said:
The TP-39 had no shoulders and would have required B-25-style gun blisters.
Ah, but that's a lengthened cockpit (2 seats), not just "moved".;) If you fit the guns in place of the 2d seat... (Or put 2/4 in the cowl?)
 
Ah, but that's a lengthened cockpit (2 seats), not just "moved".;) If you fit the guns in place of the 2d seat... (Or put 2/4 in the cowl?)

If you install the guns in the second seat, you shoot the pilot on the back. If you try to install guns in the cowl, you find out that there's not enough length left in the cowl. There's also no room for the prop cannon. You could run a couple of barrels through the pilot's armpits, but the barrels get hot, and there would be control difficulties. That's why I posted a photo, to see that it can't be done without blisters, which impair performance. They could put the pilot into a reclining position and put barrels over his head, but there goes rear visibility. Any other ideas? The nosewheel goes there, and the coolant air intake goes there. The main gear and the wing fuel tanks go there. That leaves underwing gondolas, which are blisters.
 
I've wondered what kind of plane we might have if instead of the central engine running a shaft forward to a conventionally placed single nose propeller, it ran the shaft sideways into the wings, to drive gearboxes that drive a pair of wing-mounted props. Because they don't have engines, and we have two props to do a job normally done by one, the prop area hence radius for each can be smaller, so the props can be closely coupled to the fuselage, while there would be little to no "nacelle" drag since the gearboxes can be quite compact, possibly buried completely in the wing. Also, if it helps, the props could be arranged as pusher props behind the wing instead of in front of it.

Then of course, the nose is available for a compact gun bus as on the P-38!

Also, I suggested on the P-38 thread running transmissions between the two engines on that plane, to allow for shutting down one engine and driving both props by the other, for greater range and endurance in long slow cruising.

Something that is totally not a P-38 nor a KingCobra, but perhaps an evolution, might be a two-engined version, twice the mass and area, with the two engines centrally mounted and the clutch arrangement to allow either each engine to separately drive a respective wing prop (I gather it's a bad idea to apply two IC engines to one joint load!) or for either one to drive both would be nestled between the engines.

I wonder how impractical it would be to replace the liquid-cooled engine with an aircooled radial. It means arranging a powerful fan and airflow in the engine compartment to keep it cool of course.

An advantage of the system of having a big radial stuck at the front of the plane as on many successful US designs like the Republic Thunderbolt and the Vought Corsair was, the radial engines could often keep functioning even when some of the cylinders were shot up. The engine served as forward armor for the pilot!:p

Obviously we forego that advantage with designs like either the P-39 or P-38.

Finally--no good suggestions for improving the balance of the fuel tanks, but could there have been a way to arrange the ammo so that there were two magazines, one ahead of the wing, one behind? As the guns fire, they feed into them in synchronization, so that the depletion of each matches and the CM is maintained. Obviously there is an awkward long chain from the one behind, and that has to run past some equipment that is both highly critical and runs hot--supercharger if any, and engine!:eek:

Could this have been done though?

Look at the McDonnell XP-67 The original version had an engine in the fuselage behind the Pilot and shafts going out to props on each wing. US Army Air Corps RFP 40C created several unique Aircraft including the XP-54, XP-55, and XP-56
 
Just Leo said:
If you install the guns in the second seat, you shoot the pilot on the back.
:confused::confused: So "cheek" guns, like the F-86, set further back, would, somehow, have been shooting the pilot in the back?:confused:
Just Leo said:
If you try to install guns in the cowl, you find out that there's not enough length left in the cowl. There's also no room for the prop cannon.
Fair point.
Just Leo said:
Any other ideas?
I suppose you also think belly guns are, somehow, a non-starter.:rolleyes:
 
:confused::confused: So "cheek" guns, like the F-86, set further back, would, somehow, have been shooting the pilot in the back?:confused:

Fair point.

I suppose you also think belly guns are, somehow, a non-starter.:rolleyes:

If you look at drawings, like I do, you would notice that the fuselage side doesn't taper at the right point to allow side guns of any kind to clear the cockpit. The F-86, being wider, and designed for their armament installation, does. The nosewheel uses all the space occupied by the undernose taper, and a belly gun, between the coolant system, would shoot out the retracted nosewheel. Please look at some drawings. I do this stuff as a matter of course.
 
The P-39 is unfairly criticized because the western allies (who seem to think that WW2 in the air revolved around the Battle of Britain and their own strategic bombing campaign) did not have the best experience with the type. The only real fault of the P-39 (which was not due to its basic design but decisions made by Bell and the AAF) was the deletion of the supercharger. Even then, the Russians proved it to be an excellent low altitude fighter-bomber and ground attacker, and they also claimed it could handle both the Bf-109 and Fw-190 at low altitudes in the right hands

The reasons the P-39 gets criticized primarily lie in the fact that, at the altitudes the Luftwaffe, RAF and USAAF fought in western Europe, it was limited by the low altitude rating of its engine. In both the Russian front and in the Pacific, where engagements tended to be fought at lower altitudes, the P-39 was usually able to handle itself fairly well against most enemy fighters, once its pilots understood how to use it.

I wonder if there is a way to get the Airacobra used in cab rack's by the Western Allies?
 
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