Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained) (1 Viewer)

P-39 Expert · May 21, 2021

Thumpalumpacus said:
One cannon and two .50s ain't really a suitable armament suite for 1942-43 in a plane that is struggling to keep up on performance parameters as well. Add in short range and limited altitude performance, meh.

There's a reason it was passed over. That was that it didn't deliver on promise.

The AAF and Navy both were moving to 4 .50cal MGs (about 600lbs with ammo) as was installed in the P-51A/B/C , the FM2 Wildcat and the F8F Bearcat. The Navy evaluated the 20mm cannon as being worth three 50cal machine guns and AHT says the 37mm cannon was equivalent to the 20mm. Add the two 50cal nose guns, reduce their fire about 25% for synchronization loss and they are worth about 1.5 50cal guns. So the cannon and two synchronized 50s (400-575lbs) were equivalent to 4.5 50cal MGs. Plus centerline fire. Plus the exploding shell. Pretty potent armament. If you want you can have 10 50cal MGs but that will cause a severe weight penalty. It was all about the weight.

The 1943 P-39s with the -85 engines were fully the equal of the F4U-1, F6F, FW190A, Me109G, Typhoon and superior to the A6M and Ki-43 both in speed, climb and altitude performance. I can post the graphs again for you if you want.

P-39 Expert · May 21, 2021

FLYBOYJ said:
Well it's kind of funny because IFF units were classified equipment and as mentioned several times had a destruct system built into them should a crash insure and the pilot survive. I believe in the emergency procedures in one of the P-39 flight manuals mentions activating the system if the aircraft was ever downed, so with that said I doubt that any P-39 or P-400 flying around Port Moresby had an IFF unit installed if no radar was available.

The self destruct system was set to destroy the IFF radio in the event of a crash so that it wouldn't fall into enemy hands. If it was set incorrectly it would explode when the cockpit door was slammed shut. With no radar the IFF sets should have been removed and stored until radar was installed. I don't know if they were or not.

FLYBOYJ · May 21, 2021

P-39 Expert said:
The 1943 P-39s with the -85 engines were fully the equal of the F4U-1, F6F...

Can it land on a carrier and did it have the range???

P-39 Expert · May 21, 2021

pbehn said:
This is utterly preposterous, it wasnt "the British" that changed the requirements it was the war, armour was put in planes not designed for it all over the world. The Spitfire doubled in weight for all sorts of reasons. Show me a any protest from North American discussing the P-51 about fitting more fuel inside and outside, more guns, tail warning radar, making it a dive bomber etc etc etc.

It was most certainly the British who changed the requirements, it was their production contract and it was amended more than once. They signed the initial contract without armor plate and added it during the construction process as they realized it was needed.

P-39 Expert · May 21, 2021

FLYBOYJ said:
Can it land on a carrier and did it have the range???

No it couldn't land on a carrier, but then neither could the F4U-1. And range was equivalent to either the Navy fighters.

pbehn · May 21, 2021

P-39 Expert said:
The AAF and Navy both were moving to 4 .50cal MGs (about 600lbs with ammo) as was installed in the P-51A/B/C , the FM2 Wildcat and the F8F Bearcat. The Navy evaluated the 20mm cannon as being worth three 50cal machine guns and AHT says the 37mm cannon was equivalent to the 20mm. Add the two 50cal nose guns, reduce their fire about 25% for synchronization loss and they are worth about 1.5 50cal guns. So the cannon and two synchronized 50s (400-575lbs) were equivalent to 4.5 50cal MGs. Plus centerline fire. Plus the exploding shell. Pretty potent armament. If you want you can have 10 50cal MGs but that will cause a severe weight penalty. It was all about the weight.

The 1943 P-39s with the -85 engines were fully the equal of the F4U-1, F6F, FW190A, Me109G, Typhoon and superior to the A6M and Ki-43 both in speed, climb and altitude performance. I can post the graphs again for you if you want.

No they werent, by the end of 1943 the Typhoon was a fighter bomber, and was carrying a massive amount of extra internal armour in addition to being rock steady at 400MPH. The Typhoon as an interceptor ended the Fw 190 tip and run raids, could the P-39 do that? It eventually dropped bombs fired rockets and when it had dont that was still a 4x 20mm cannon armed fighter that could ruin your whole day could the P-39 do that?

fubar57 · May 21, 2021

P-39 Expert said:
No it couldn't land on a carrier, but then neither could the F4U-1. And range was equivalent to either the Navy fighters.

The British flew F4U-1s off of carriers in Nov. '43

pbehn · May 21, 2021

Winkle Brown landed and took off from carriers in a P-39 then used the plane as his own run about, there would be issues with it in operations, mainly range and not being very good at anything.

FLYBOYJ · May 21, 2021

P-39 Expert said:
The self destruct system was set to destroy the IFF radio in the event of a crash so that it wouldn't fall into enemy hands. If it was set incorrectly it would explode when the cockpit door was slammed shut. With no radar the IFF sets should have been removed and stored until radar was installed. I don't know if they were or not.

I'll bet dollars to donuts there wasn't a P-39 or P-400 flying around the SWP (Port Moresby 1942) with an IFF installed so your argument about removal of these units is a mute point.

So the only thing that YOU think "could have" hypothetically helped the P-39 in the SWP was the removal of the wing guns (I agree) and the removal of the GB armor. I clearly showed you by leaving it in the C/G moved up over 2 inches putting the C/G right in the middle of the envelope in both the loaded and empty configuration.

Again - ask yourself way the Russians left it in???? At the end of the day this 70 pounds would not have made a difference, would not have made the P-39 any faster or more maneuverable but safer to fly - oh yea, with the radios in the tail no less!!!

FLYBOYJ · May 21, 2021

P-39 Expert said:
No it couldn't land on a carrier, but then neither could the F4U-1. And range was equivalent to either the Navy fighters.

Equivalent (in your opinion) - not better!!!

pbehn · May 21, 2021

P-39 Expert said:
It was most certainly the British who changed the requirements, it was their production contract and it was amended more than once. They signed the initial contract without armor plate and added it during the construction process as they realized it was needed.

No, they realised it wasnt in the contract, it was needed since before the Battle of Britain, armour and self sealing tanks were part of being a fighter from the battle of France, you are advocating allied pilots being in death traps that Zero pilots were, but the Zero had an excuse, it had phenomenal range.

P-39 Expert · May 21, 2021

pbehn said:
No they werent, by the end of 1943 the Typhoon was a fighter bomber, and was carrying a massive amount of extra internal armour in addition to being rock steady at 400MPH. The Typhoon as an interceptor ended the Fw 190 tip and run raids, could the P-39 do that? It eventually dropped bombs fired rockets and when it had dont that was still a 4x 20mm cannon armed fighter that could ruin your whole day could the P-39 do that?

Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And one hit from a 37mm cannon will definitely ruin your day no matter what you are flying.

FLYBOYJ · May 21, 2021

P-39 Expert said:
Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And one hit from a 37mm cannon will definitely ruin your day no matter what you are flying.

But wait, what happened to the lighter 20mm we were talking about yesterday? Now 120 lbs more in the nose is ok?

ThomasP · May 21, 2021

re the IFF in early P-39s in the PTO.

The first IFF used by the US was the UK IFF 'Pipsqueak' or RC-96-A in US terms, which was basically just an intermittent broadcast circuit for the radio transmitter set. This sent out a predetermined pulse of abut 14 seconds, switched back to normal radio operation for a predetermined time, then sent out the 14 sec pulse again, etc. The frequency of the pulse was the same as the radar detecting it.

I know this was used with the SCR-522 VHF set (BC-608-A) fitted in the P-39 in the PTO. I have seen diagrams and weight lists.

I think it was also used in some of the early airframes fitted with the SCR-274 HF sets (BC-608-A & BC-616). I have seen weight lists but not any diagrams of the fit.

I have also read accounts about the US using 'Pipsqueak' in the PTO but I do not remember where or exactly why, other than to help not get shot down by US or Australian friendlies.

edit: deleted the "Mk I" part of "IFF Mk I", as the Mk I IFF was a different system. oops

pbehn · May 21, 2021

P-39 Expert said:
Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And one hit from a 37mm cannon will definitely ruin your day no matter what you are flying.

So could the P-39 do it at high altitude? Your chances of hitting anything with one 37mm cannon are massively smaller than with 4x 20 mm cannon. Just face facts, the P-39 was the USAs Gloster Gladiator, it did a job until better stuff was available.

P-39 Expert · May 21, 2021

FLYBOYJ said:
But wait, what happened to the lighter 20mm we were talking about yesterday? Now 120 lbs more in the nose is ok?

The 20mm cannon was just an example to illustrate that Bell was able to balance the P-39/400 with either cannon in the nose even though one was 140lbs lighter than the other. Surely you know that, right?

P-39 Expert · May 21, 2021

pbehn said:
So could the P-39 do it at high altitude? Your chances of hitting anything with one 37mm cannon are massively smaller than with 4x 20 mm cannon. Just face facts, the P-39 was the USAs Gloster Gladiator, it did a job until better stuff was available.

Seriously? The Gladiator was a 250mph biplane.

Thumpalumpacus · May 21, 2021

P-39 Expert said:
The AAF and Navy both were moving to 4 .50cal MGs (about 600lbs with ammo) as was installed in the P-51A/B/C , the FM2 Wildcat and the F8F Bearcat. The Navy evaluated the 20mm cannon as being worth three 50cal machine guns and AHT says the 37mm cannon was equivalent to the 20mm. Add the two 50cal nose guns, reduce their fire about 25% for synchronization loss and they are worth about 1.5 50cal guns. So the cannon and two synchronized 50s (400-575lbs) were equivalent to 4.5 50cal MGs. Plus centerline fire. Plus the exploding shell. Pretty potent armament. If you want you can have 10 50cal MGs but that will cause a severe weight penalty. It was all about the weight.

The 1943 P-39s with the -85 engines were fully the equal of the F4U-1, F6F, FW190A, Me109G, Typhoon and superior to the A6M and Ki-43 both in speed, climb and altitude performance. I can post the graphs again for you if you want.

Actually, the USAAF had moved to six .50s in the -51, eight in the -47, four .50s and a cannon in the -38, and the Navy in 1943 had standardized on the F6F's six .50s, so I'm seeing a bit of underselling here on your part. Oh, and the F4U1 had six .50s as well.

If you're pulling guns, armor, and the goddamned radio to get climb or maneuverability, your plane probably ain't cutting the mustard.

pbehn · May 21, 2021

P-39 Expert said:
Seriously? The Gladiator was a 250mph biplane.

Yes seriously. Performance in numbers is immaterial, the Gladiator saw service in the Battle of France, Battle of Britain, Malta and North Africa and was replaced ASAP by better aircraft. It achieved "air superiority" over the Italians in Ethiopia in June 1941.

Glider · May 21, 2021

P-39 Expert said:
Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And one hit from a 37mm cannon will definitely ruin your day no matter what you are flying.

No one would deny that there was a disappointment in the altitude performance of the Typhoon, but your statement Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude is as ever, far too simplistic.

The RAF had the Spitfire as an interceptor which was always very effective at altitude. What the Typhoon had in its favour was the following:-
a) an exceptional low level performance at low / medium altitude Reaching approx 400mph at 8,800ft 415mph at 20,000ft, a lot faster than a Spitfire
b) The capability of carrying very heavy payload of up to 2,000lb plus of course 4 x 20mm
c) It was well armoured with pilot eventually sitting in almost a bath of armour

Lets look at those parameters on the P39
a) P39N 398 mph at 9,700ft 389 mph at 16,100ft Both are very quick and its likely that the inevitable differences you get in mass production would make them very similar.
b) I am not sure what the GA capability of the P39 is but it seems to be in the area of 500lb of bombs which isn't even close to the capability of the Typhoon
c) Again I haven't seen anything that shows the P39 as having anything remotely close to the armour protection of the Typhoon
Note the P39Q seems to have a worse performance

The RAF lacks a GA aircraft and the Typhoon had all the right attributes, that's why it was the RAF's premier GA aircraft.

Your comment about the effect of a hit by the 37 is, again overly simplistic. You are correct in that a hit would ruin anyone's day but compared to the 20mm Hispano II

37mm rof 150 rpm mv 2,000ft/min
20mm rof 600 rpm mv 2,700ft/min

You are far more likely to be hit by multiple 20mm rounds which would also ruin anyone's day

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