Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)

[buffnut453]

There are so many P-39 threads that I simply can't keep up. I think I'm suffering from a kind of mania where I can't stop myself from checking in the vain hope that there's actually some new material or perspectives. I'm almost always disappointed.

 

[FLYBOYJ]

Was there ever a P-39 with a gross weight of 5,500lb? Not sure that any of the prototypes even reached that mark.

All your arguments for throwing away armour, IFF, moving radios, ditching guns, etc, only brings the weight down to 7,150lb to 7,250lb according to your estimations. What happened to the other 1,600+lb?

Perhaps if you throw out all the armour, all the guns and ammo you may get close. But what use is that?

Also, since you are arguing that the British should have had the P-39 without the "extra weight", the IFF should definitely stay. Because the British had radar and their aircraft had IFF.

According to Greg's W&B calculator, if you removed all armor and guns and gunsight (what use is the gunsight without guns, right?) The weight comes down to 5,684 empty, 6,489 with fuel and oil

 

[DerAdlerIstGelandet]

There are so many P-39 threads that I simply can't keep up. I think I'm suffering from a kind of mania where I can't stop myself from checking in the vain hope that there's actually some new material or perspectives. I'm almost always disappointed.

And I am getting sick and tired of every thread being hijacked because of a P-39 fetish.

 

[wuzak]

Also they no longer needed them since the BoB was over and there would be no German invasion. And this was a cash contract not under lend-lease so they didn't want to pay for them.

Since the Airacobra I didn't even start flight testing until April 1941 in the USA, I'm not sure how the BoB was relevant to the decision to keep or not keep the ordered aircraft.

From Airacobra I for RAF, P-400

No. 601 Squadron pilots found numerous flaws and weaknesses during their initial work-up with the the Airacobra. Some of them were a question of improving operational efficiency and pilot comfort, but others were considered essential to make the aircraft operational. Numerous modifications were made in the field in an attempt to make the aircraft suitable for combat. A master valve was introduced to allow oxygen to be turned on from the cockpit. The gunsight was modified to improve forward visibility. Changes to the ammunition tanks for the wing guns were made. Modifications were made to the cockpit harness release in order to simplify the operation. The IFF (Identification, Friend or Foe) set was removed from behind the pilot, where it obstructed aft view. A throttle control quadrant friction damper was introduced.

One wonders if the IFF set behind the pilot impaired rear view, why would the AAF or Russians put a radio set there?

The Airacobra was considered to be very suitable for low altitude operations because of the excellent view and controllability, and it was fully maneuverable at speeds above 160 mph. It was not difficult to fly at night, but the exhaust flames could be seen by another aircraft flying three miles to the rear. The flash from the nose guns was blinding, and could cause the pilot to lose not only his target but also his night vision. Firing of the nose guns caused the buildup of carbon monoxide contamination in the cockpit, and this could reach a lethal level very quickly. The guns were fairly inaccessible, and maintenance was troublesome.

In spite of the problems with the compass and the need for flame dampers for the exhaust and flash suppressors for the nose guns, the RAF concluded that the Airacobra would make an excellent day fighter at altitudes below 20,000 feet and was well suited for the ground-attack role. However, before these plans could be implemented, a decision was made to divert the bulk of the British Airacobra contract to Russia.

Who made that decision? The British, the Americans, or was it a mutual decision?

Now, British P-39s had the 4 0.303" lmgs in the wings, which added weight, but they also had the lighter 20mm Hispano in the nose. I don't know the weights of these various things, so how much extra/less weight did the Airacobra I have in guns and ammo vs the P-39C, on which it was based?

Baugher does not mention that there was any additional armour in the Airacobra I.

 

[Peter Gunn]

According to Greg's W&B calculator, if you removed all armor and guns and gunsight (what use is the gunsight without guns, right?) The weight comes down to 5,684 empty, 6,489 with fuel and oil

Not to put too fine a point on it but uh... where's this 5,500lb empty weight P-39 Expert keeps coming up with?

 

[wuzak]

According to Greg's W&B calculator, if you removed all armor and guns and gunsight (what use is the gunsight without guns, right?) The weight comes down to 5,684 empty, 6,489 with fuel and oil

It is not surprising that the performance estimates of the P-39 at 5,500lb was not reflected in reality!

And from Baugher's site again:

Unfortunately, Bell's glossy advertising brochures did not distinguish between the performance of a lightly-loaded, unarmed, highly-polished experimental prototype and a production fighter heavily-loaded with military equipment and armament, and the British were to rue the day that they ever looked at an Airacobra.

 

[wuzak]

Not to put too fine a point on it but uh... where's this 5,500lb empty weight P-39 Expert keeps coming up with?

I think that was the weight that the original XP-39 was supposed to have, but never did.

 

[FLYBOYJ]

And I am getting sick and tired of every thread being hijacked because of a P-39 fetish.

Yep - I think one thread is good enough for Groundhog's Day!

 

[FLYBOYJ]

It is not surprising that the performance estimates of the P-39 at 5,500lb was not reflected in reality!

Oh - I forgot, Take away ALL the radios AND the IFF and you're down to about 5384 empty, 6189 with fuel and oil.

So the 5,500 pound claim can be made with no guns, no armor, no radios and no fuel!

 

[pbehn]

Oh - I forgot, Take away ALL the radios AND the IFF and you're down to about 5384 empty, 6189 with fuel and oil.

So the 5,500 pound claim can be made with no guns, no armor, no radios and no fuel!

I can understand the need for some fuel, as long as no one gets carried away, but surely you dont need much oil?

 

[GrauGeist]

The only P-39 that was close to 5,000 pounds empty (but still equipped) wasn't even a P-39, it was the navy's XFL-1.

And it had nose armor...

 

[DerAdlerIstGelandet]

Yep - I think one thread is good enough for Groundhog's Day!

View attachment 624125

Yeah just merge all of the P-39 threads into this one. It's easier to ignore just one thread. Of course, as moderators we do not have the luxury of ignoring it.

 

[DerAdlerIstGelandet]

All P-39 discussion is now to be conducted in this thread, and this thread alone.

 

[pbehn]

And it had nose armor...

Then I conclude that it was noted early on that the P-39 had CoG issues and the weight to solve the issue was added as armour.

 

[glennasher]

Oh - I forgot, Take away ALL the radios AND the IFF and you're down to about 5384 empty, 6189 with fuel and oil.

So the 5,500 pound claim can be made with no guns, no armor, no radios and no fuel!

So, a lawn ornament, then?

 

[SaparotRob]

With regard to the answers from pbehn and Peter Gunn, why would one want to divert engines or better engines to the inferior airframe?

 

[Peter Gunn]

With regard to the answers from pbehn and Peter Gunn, why would one want to divert engines or better engines to the inferior airframe?

HERETIC!!! Why would you bring logic into this discussion?

 

[Shortround6]

Now if we take out the large front teeth and streamline the nostrils a bit...................................................................................

 

[GregP]

I went back to page 62, after finding that the thread name was changed, and put in a couple of pics of the P-63A engine compartment. Just FYI.

I compliment the moderators in consolidating the P-39 comments into this thread. Now we can simply ignore it going forward if we like. I like that option.

Cheers.

 

[GrauGeist]

Then I conclude that it was noted early on that the P-39 had CoG issues and the weight to solve the issue was added as armour.

The XFL didn't have the 37mm (though it could) but instead, either a 20mm or .50MG and interestingly enough, it was a conventional gear layout (tail dragger) as the nose-gear was eliminated.
So there was all sorts of CoG shuffling going on.