Improve That Design: How Aircraft Could Have Been Made Better

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And to touch on the P-39 armor "thing" - I appreciate the exhaustive attempts to try to reimagine the P-39 into a world beater by moving this and eliminating that, so it would maybe, somehow, be better than it was.

So let's do this:
We'll remove the gearbox armor and while we're at it, let's remove the 2 gallon oil tank, too. Then let's get rid of the Olds 37mm cannon, way too heavy.
It seems to me that the driveshaft assembly is extra weight we don't need, so that goes.
What's next - oh yeah, CoG issues, so let's move the engine to the front where all that empty space is and maybe adjust the mainwing a bit to balance things out. Nice.
Now the two cowl .50MGs will have to go in the wings with the others, of course.
Ahh yeah, let's get rid of the nosegear, way too heavy - a tailwheel will do just fine, less weight, you know.

So now we get to see the what we've created and...what do we have? A P-40 - that's what we have.

Someone better get the DeLorean and go back and tell Bell!
 
Find one instance where the driveshaft gave way. One. 9500 examples produced, in combat all over the world in all kinds of weather.

Find one instance where a P-39 took a round in the nose armor. One. In all of history.

Dead men tell no tales? Well you're telling a big one right now.
 

Since there's no evidence, there's no evidence that it happened, either. One way to see how likely gearbox damage is to examine the damage records of twins, especially twin fighters.
 
So now we get to see the what we've created and...what do we have? A P-40 - that's what we have.
No, we have a smaller, lighter, P40 wannabe that probably can outperform the P40 in the interceptor role, but is nowhere near as versatile, and can't hold a candle to it in attack and CAS modes. That small wing with its symmetrical airfoil impairs its ordnance lift capacity and increases its runway length requirements.
 
Of course, I was being facetious, but in reality, there was only a few feet difference (length/width) between the two.

Now Bell's XP-77 was most certainly smaller - but definately no better than the P-39's spin-offs: XFL, XP-76.
 

Again YOU HAVE NO IDEA WHAT THE CONVERSATION IS ABOUT!

It is about the armor in front of the gearbox.

ARMOR THAT WOULD NOT STOP A 20mm SHELL.
 

The P-40 had two advantages over the P-39:
1. longer range on internal fuel;
2. early production. 7,478 P-40s and 2,912 P-39s were delivered by the end of '42.

As for being "more versatile," P-40 production began in May 1940 and stopped in November 1944 with 13,738 built.
Nothing replaced it on Curtiss assembly lines.

P-39 production began in December 1940 and ended in August '44 with 9,588 built; P-63 production began in January '44 (31 P-63s were delivered in '43) and continued through June '45 with 3,303 built (including 30 delivered between September 1945 and April 1946) for a total of 12,891 'Cobras built.

Both lines slowed down from peaks of 463 P-40s in August '43 and 503 P-39s July '43 to 200 P-40s in May '44, with 201 P-39s and 110 P-63s the same month.

The US didn't need the P-39/63 by early '44; they were built for the USSR.

The USSR wanted P-39s and P-63s.

The US didn't need any P-40s by early '44 and the USSR didn't want anymore P-40s; so P-40 production ended.

Being "more versatile," whatever that means, didn't keep the P-40 in demand as long as the P-39/63 line.
 


I got my engine model info from USAF Engine Models

The chart does not say how many of a specific model carried the specified engine; could be one, could be more of the production run.
 

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QUOTE="jmcalli2, post: 1609575, member: 45349"]Once again, a bullet would not shake the drive shaft loose
It wouldn't need to. What's going to happen when a hollow tube carrying the torque from 1150 HP in walls .020" thick at 3,000 RPM, carefully balanced and tuned to avoid resonances, is holed or furrowed by a 7.7MM round, upsetting all that balancing and tuning? I suspect the shaft would shake itself loose, possibly ripping the intermediate coupling loose from its supporting structure.

Actually, it is. Imagine you're in a dogfight, pulling 3,000 RPM and all the MP the supercharger will give you, plus fluctuating G and gyroscopic loads from your gyrations, and your reduction gearbox is disabled, suddenly unloading that engine right behind your seat. Wide open throttle and no load on the crankshaft, what do you think is going to happen? Right, it's going to come unglued. Spectacularly. The only question is how many revs it'll hit before it does. 3,500? 4,000? Who cares? You won't. The scalding glycol and engine oil will have seen to that. And nobody will be around to tell the tale.
Reduction gearbox armor was essential.[/QUOTE]

I disagree.

Because the drive shaft is supported front and midsection by the main structural beam of the aircraft.

Because if your "I KNOW" scenarios were true, EVERY Sikorsky helo would have had that problem; radial engine with drive shaft going through the cabin.

So, once again, show me some documentation OTHER THAN "Oh, I KNOW."

I'm still waiting.

As for hot glycol, that is BELOW and BEHIND the pilot int the P-39;

Perhaps you are confused by the P-40, with the coolant and oil radiators in front of the pilot, where one little bullet could scald him?
Then the P-40 was a deathtrap! It should have had foot-thick armor in front of those radiators!
 
Again YOU HAVE NO IDEA WHAT THE CONVERSATION IS ABOUT!

It is about the armor in front of the gearbox.

ARMOR THAT WOULD NOT STOP A 20mm SHELL.

I'm beginning to wonder if you do.
I'm pointing out that .30 caliber proof armor is minimum armor, no aircraft I'm aware of carried a smaller caliber weapon, while almost any axis aircraft you would meet ( with the exception of the Ki-43 early in the war) had additional guns that were bigger than .30 cal.
So just what good did the armor do?
What Larry Bell did IMO was create a aircraft that was so different from other aircraft it was dangerous.
Right at the end of a combat mission when the ammo is low or out, and the pilots flying skills aren't the best because he's probably dog tired.
Most aircraft handle the best at the end of the flight, if there's no battle damage, lower total weight, lower stalling speed, etc.
But in the P-39's case that's when it's most sensitive, with close to aft CG.
Pull that turn to final a little too tight, or rough, and you'll end up in a stall/spin that'll take more altitude to recover from than you've got.

Most aircraft destroyed in combat in the WW2 era would get no investigation under most conditions.
The pilot, if he survived, sometimes might have a clue. His squadron friends might see it, but are likely too busy with the mission, or their own survival , to really concentrate on exactly what happened.
And even if they could find a secure crash site, no one had the time to do a complete forensic investigation on a smoking hole in the ground, like modern crash investigations .

I feel like this is a waste of time trying to have a adult conversation with someone who evidently has no knowledge beyond what he reads, and has no real experience with anything mechanical.
 
The P-39L was built with both -63 and -83 engines. Basically, the P-39L was a P-39K with a Curtiss Electric propeller and a modified nosewheel.

The -63 has 7.48 : 1 supercharger gearing. It had 1325 hp at S.L. and 1100 hp at 13,800 ft and 44.2 in. Hg.

The -83 had 9.60 : 1 supercharger gearing. It had 1200 hp at S.L. and 1125 hp at 15,500 ft. and 38.8 in. Hg.

Both airplanes were likely flown at considerably higher power settings than 39" - 44" Hg by the Soviets, so they likely got sprightly performance that another 300 - 400 hp would offer.

So, the -63 was better way down low and the -83 was better a couple of thousand feet higher than the -63 airplane ... but neither one should have had a decisive difference in flight performance except for shorter takeoff in the -63 airplane and slightly better very low-altitude climb performance.

In service, there was no problem with drivehsaft failures. There wll might have been combat drivehsaft failures, but there were NONE in-service in airplanes that returned from combat.
 
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Interesting - I've seen photographs and guncam footage showing aircraft being attacked and in the process, engines falling away, landing gear dropping, control surfaces flying off, canopy structures blown out and a whole host of other indications of deadly fire.

But aparently Bell was a genius and built an indestructible machine that can defy the laws of physics...
 
Perhaps you are confused by the P-40, with the coolant and oil radiators in front of the pilot, where one little bullet could scald him?
Then the P-40 was a deathtrap! It should have had foot-thick armor in front of those radiators!
The P40 had a firewall between the propulsion compartment and the rest of the airframe, as front engine planes generally do. They are made of stainless steel, ruggedly constructed to take the stresses of the engine mounts bolted to them, and generally do their job well, keeping engine related fluids and risks out of the rest of the plane. Anyone who's had grease under their fingernails from working on airplanes knows this.

As for hot glycol, that is BELOW and BEHIND the pilot int the P-39;
In all the drawings and photos I've seen of P39s in service, being maintained, or under construction, there doesn't seem to be any sort of a solid secure firewall between the engine compartment and the cockpit, and the radiator and oil cooler plumbing run right under the pilot's feet. The engine mounts appear to be supported by the lower fuselage "backbone" beams rather than cantilevered from a firewall in the usual manner. This means that cockpit and engine compartment form a cocoon that will confine and contain any escaped hot fluids, frying the pilot. Not my favorite way to go.
 
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The -63 engine had the same 8.8 supercharger gears as the -35. The 7.48 geared engines were all two stage.

The 9.6 engines developed the same 1150HP as the 8.8 engines, just at about 3000ft higher critical altitude. At the same altitude, the 9.6 engines developed about 100HP more than the 8.8 engines above about 9000ft. Gave the P-39N a big performance edge over the D/F/K/L at the same weights. See attached chart.

I don't know of any L models with the -83 engine, otherwise they would be Ms.
 

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