Improve That Design: How Aircraft Could Have Been Made Better

[GrauGeist]

Damn straight. Is there a way to filter out P-39 chat within a thread?

It'll pass in time.
Every so often this sort of thing comes up - before the P-39, it was a P-40 discussion if I remember right, that ran well past it's point of being useful.

 

[swampyankee]

Back to how aircraft could be made better....

F4U Corsair: floorboards under cockpit and some seat adjustments so somebody shorter than a 75th percentile male would fit properly

Single-engine fighters in general: Standardize on cockpit layout. Bluntly, it's not exactly rocket science to have the instruments and controls in similar locations on different aircraft.

P-38: Put generators on both engines (the aircraft had Curtiss Electric propellers. It needed electricity to fly)

 

[GregP]

Regarding Post #1059:

The top fighter in the Pacific flown at military power loaded for combat against the bottom fighter flown at WER and light enough to be useless on a mission?

That's useful! Thanks!

You'd be a lot better off and a lot more believable if you stick to the numbers from the Pilot's Operating Handbook rather than lightweight WER tests. The P-39N was nowhere NEAR what you posted when it was flown at normal weihgts and Normal power settings.

 

[tyrodtom]

Regarding Post #1059:

The top fighter in the Pacific flown at military power loaded for combat against the bottom fighter flown at WER and light enough to be useless on a mission?

That's useful! Thanks!

You'd be a lot better off and a lot more believable if you stick to the numbers from the Pilot's Oprating Handbook rather thanh lightweight WER tests. The P-39N was nowhere NEAR what you posting when it was flown at normal weihgts and Normal power settings.

You wasting your breath. well, not really breath, but typing skills.
He's already been told that how many times ?

 

[GregP]

Yeah, I suppose you are correct. Ah well ... one retains hope.

Cheers, Tyrodtom. And no P-39s, unless you REALLY want one.

 

[P-39 Expert]

Regarding Post #1059:

The top fighter in the Pacific flown at military power loaded for combat against the bottom fighter flown at WER and light enough to be useless on a mission?

That's useful! Thanks!

You'd be a lot better off and a lot more believable if you stick to the numbers from the Pilot's Oprating Handbook rather than lightweight WER tests. The P-39N was nowhere NEAR what you posted when it was flown at normal weihgts and Normal power settings.

P-39 weight was listed at average weight for a flight, fully loaded with half fuel. Took off with full fuel, landed with minimum reserve. British used 95% of gross weight to allow for fuel burn. Hellcat flown at WER, as was P-39 except no WER above 17000ft. Standard tests for AAF and USN.

Pilot's manual was a guide for pilots, not the results of a performance test. Climb (and range) almost always lower in the manual than on an official test to give the pilot a reserve. Hellcat manual had no similar climb chart, only listed time to climb with no feet per minute figures at different altitudes.

 

[PAT303]

P-39 weight was listed at average weight for a flight, fully loaded with half fuel. Took off with full fuel, landed with minimum reserve. British used 95% of gross weight to allow for fuel burn. Hellcat flown at WER, as was P-39 except no WER above 17000ft. Standard tests for AAF and USN.

Pilot's manual was a guide for pilots, not the results of a performance test. Climb (and range) almost always lower in the manual than on an official test to give the pilot a reserve. Hellcat manual had no similar climb chart, only listed time to climb with no feet per minute figures at different altitudes.

If the P39 was all the things you claim it was it would have been used across all theatres in all roles like all the great fighters were, Spitfire, Hurricane, Me109, FW190, P40, P47, P51, Wildcat Hellcat the list goes on, the P39 was a donkey in a world of thoroughbreds, move along people, nothing to see.

 

[Admiral Beez]

F4U Corsair: floorboards under cockpit and some seat adjustments so somebody shorter than a 75th percentile male would fit properly

Doesn't the P-47 have the same issue? I'd probably drop my Big League Chew into the bowels of the aircraft.

 

[GrauGeist]

Wasn't there was a joke about the P-47's cockpit size, I believe came from the RAF?
Something like: "When bounced by the Germans, you could run around and hide."

 

[GregP]

Hi P-39 Expert,

OK, P-39 Expert, let's take a look at it.

I'll use a P-39N-1 at 7,514 lbs. That's basic airplane plus full internal fuel (87 gallons) and no center tank. Let's say we cruise at 15,000 feet.

1) Takeoff and climb to 5,000 feet uses 20 gallons and gets you 5.42 miles from brake release. You can do the math.

2) Climb from 5,000 feet to 15,000 feet takes 4.7 minutes at 142 gal/hrs and uses another 11.12 gallons. It also gets you another 11.714 miles from brake release.

3) Let's say you have an action sorties in which you are at combat power for 6 minutes. You basically don't go anywhere, but you use 13.80 gallons of fuel.

4) Now, instantly, you go from combat to cruise flight and you choose to cruise at 2,200 rpm, 31" MAP, for a fuel burn of 59 gallons per hour. That means you have 42.79 minutes of flight at 247 mph, which means another 176.15 miles.

5) So, the total range is 193.28 miles from brake release, or less than 100 miles out and back. In the Pacific, that means the P-39 was a viable airplane on full internal fuel and no aux fuel if it was flying between the islands in Hawaii. If you don't engage in any combat, the range goes up to 251 miles under the above conditions. The conditions do not allow for fuel reserve.

Not very useful. You can get out 300 – 345 miles if you cruise at absolute economy power. But, getting caught cruising at 194 mph by a Zero means you are right in the middle of his best-performance airspeed range. Not a good place to be if you are the P-39 pilot. If you cruise at 250 mph, your range is less than 250 miles one-way, which means a 125-mile mission range.

Again, not very useful when the Pacific Ocean is your playground. You can get as many as 430 statute miles, but you'll be cruising at 160 - 194 mph, so don't get caught by a Zero (or any other Japanese fighter). If you DO happen to need 5 minutes of combat, and you are out at the max range, you won't get back home before running out of fuel. The range tables don't allow for combat.

With the 75-gallon aux tank, you can get out to 694 miles, but that is at best economy power and low-speed (160 – 194 mph) cruise, with no allowance for combat. To actually get to the max range, you'd have to basically fly the entire mission at best economy cruise power (2,000 rpm). Nobody who wanted to live would go into a potential combat area where he expected to see enemy aircraft at economy cruise. So, the max range is basically a ferry flight with no combat.

So, the P-39 looks like it could be a useful fighter for local defense and short-range attacks. That only helps offensively if there are short-range targets around. In the Pacific, there were in some island chains, notably around Port Moresby and similar island chains. Not so much if you were flying out of an island with nothing around for hundreds of miles.

In total, it doesn't look very useful, and it didn't prove to be so in real life during WWII in the Pacific.

In the Russian steppes, the targets could be only a few miles or a few tens of miles away, so it wasn't range-limited and the space between the launch airfield and the target was ground and not water. That meant if you had to get out of the P-39, you could walk home if you had to. A completely different scenario from the Pacific where going down might mean a LONG swim. Heck, in a flight suit a 100-foot swim was a long one.

The above come from the POH, not the lightweight WER test report.

 

[GregP]

Hi Graugeist,

I hear they said you could take evasive acion by jumping about in the cockpit.

But it all means the same thing, the P-47 was a LARGE aircraft if you were coming from a Spitfire.

When I got into a P-47D, the size of the cockpit was a surprise, It was large and comfortable compared with any other fighter. The smallest cockpit I've been in is a Messerschmitt Bf 109 (actually a Hispano Ha.1112 Buchon; same as a Bf 109). If you aren't claustrophobic, you might get that way in a Bf 109. An F4U Corsair is pretty roomy, but if you drop anything (like a map or a pencil) it will likely fall into the belly and get tangled in the control cables.

 

[GrauGeist]

I've been in the cockpit of a Bf109E (it was hangared in Chino back in the 70's) and it was certainly a tight fit - even though I was in my late teens, I stood 6'1" and there was almost zero room between the canopy ceiling and my head. I have no idea how those guys did it!
I have also been in the cockpit of an SNJ, and it's also a pretty tight fit, although it had better elbow room than a 109

 

[P-39 Expert]

Hi P-39 Expert,

OK, P-39 Expert, let's take a look at it.

I'll use a P-39N-1 at 7,514 lbs. That's basic airplane plus full internal fuel (87 gallons) and no center tank. Let's say we cruise at 15,000 feet.

1) Takeoff and climb to 5,000 feet uses 20 gallons and gets you 5.42 miles from brake release. You can do the math.

2) Climb from 5,000 feet to 15,000 feet takes 4.7 minutes at 142 gal/hrs and uses another 11.12 gallons. It also gets you another 11.714 miles from brake release.

3) Let's say you have an action sorties in which you are at combat power for 6 minutes. You basically don't go anywhere, but you use 13.80 gallons of fuel.

4) Now, instantly, you go from combat to cruise flight and you choose to cruise at 2,200 rpm, 31" MAP, for a fuel burn of 59 gallons per hour. That means you have 42.79 minutes of flight at 247 mph, which means another 176.15 miles.

5) So, the total range is 193.28 miles from brake release, or less than 100 miles out and back. In the Pacific, that means the P-39 was a viable airplane on full internal fuel and no aux fuel if it was flying between the islands in Hawaii. If you don't engage in any combat, the range goes up to 251 miles under the above conditions. The conditions do not allow for fuel reserve.

Not very useful. You can get out 300 – 345 miles if you cruise at absolute economy power. But, getting caught cruising at 194 mph by a Zero means you are right in the middle of his best-performance airspeed range. Not a good place to be if you are the P-39 pilot. If you cruise at 250 mph, your range is less than 250 miles one-way, which means a 125-mile mission range.

Again, not very useful when the Pacific Ocean is your playground. You can get as many as 430 statute miles, but you'll be cruising at 160 - 194 mph, so don't get caught by a Zero (or any other Japanese fighter). If you DO happen to need 5 minutes of combat, and you are out at the max range, you won't get back home before running out of fuel. The range tables don't allow for combat.

With the 75-gallon aux tank, you can get out to 694 miles, but that is at best economy power and low-speed (160 – 194 mph) cruise, with no allowance for combat. To actually get to the max range, you'd have to basically fly the entire mission at best economy cruise power (2,000 rpm). Nobody who wanted to live would go into a potential combat area where he expected to see enemy aircraft at economy cruise. So, the max range is basically a ferry flight with no combat.

So, the P-39 looks like it could be a useful fighter for local defense and short-range attacks. That only helps offensively if there are short-range targets around. In the Pacific, there were in some island chains, notably around Port Moresby and similar island chains. Not so much if you were flying out of an island with nothing around for hundreds of miles.

In total, it doesn't look very useful, and it didn't prove to be so in real life during WWII in the Pacific.

In the Russian steppes, the targets could be only a few miles or a few tens of miles away, so it wasn't range-limited and the space between the launch airfield and the target was ground and not water. That meant if you had to get out of the P-39, you could walk home if you had to. A completely different scenario from the Pacific where going down might mean a LONG swim. Heck, in a flight suit a 100-foot swim was a long one.

The above come from the POH, not the lightweight WER test report.

You're doing this the hard way. Straight from the pilot's manual. If range is important then use the full 120gal internal, we're in the Pacific, not the Russian steppes. And lets cruise at 20000ft just in case we do get jumped by Zeros. Deduct 20gal for takeoff and climb to 5000ft, 32gal for a full 20minutes of combat at 20000ft, and a 10gal reserve for landing. That leaves us with 58gal for cruise out and back at 35gph or 1.7 hours at 224mph TAS is 380miles. Not 193. That's with a full 20 minutes at combat power at 20000ft.

Now virtually every mission was a drop tank mission so let's use the 110gal external tank most common in the Pacific. And let's go on up to 25000ft in case we meet any Zeros. Start with 230gal (120+110) less the same 20gal for takeoff, 24gal for combat at 25000ft and landing reserve of 10 gal. That leaves 176gal for cruising at 62gph or 2.8hours of cruising time at 276mph or 772miles. Full 20min combat at 25000ft and a 10gal landing reserve.

The F6F-3 stat sheet shows a combat radius of 335mi with a 150gal drop tank, but the USN figured theirs differently. Figured like an army mission use 400gal (250 internal and 150 drop) less 45gal takeoff and climb to 5000ft, 93gal for 20 min combat at 25000ft and a 20gal reserve for landing. That leaves 242gal for cruising at 93gph (max cruise) or 2.6hours. About the same as the P-39N at 2.8hrs. Max cruise is not max continuous (normal) which used 250gph at 25000ft, that would give you less than 1hr.

 

[PAT303]

You're doing this the hard way. Straight from the pilot's manual. If range is important then use the full 120gal internal, we're in the Pacific, not the Russian steppes. And lets cruise at 20000ft just in case we do get jumped by Zeros. Deduct 20gal for takeoff and climb to 5000ft, 32gal for a full 20minutes of combat at 20000ft, and a 10gal reserve for landing. That leaves us with 58gal for cruise out and back at 35gph or 1.7 hours at 224mph TAS is 380miles. Not 193. That's with a full 20 minutes at combat power at 20000ft.

Now virtually every mission was a drop tank mission so let's use the 110gal external tank most common in the Pacific. And let's go on up to 25000ft in case we meet any Zeros. Start with 230gal (120+110) less the same 20gal for takeoff, 24gal for combat at 25000ft and landing reserve of 10 gal. That leaves 176gal for cruising at 62gph or 2.8hours of cruising time at 276mph or 772miles. Full 20min combat at 25000ft and a 10gal landing reserve.

The F6F-3 stat sheet shows a combat radius of 335mi with a 150gal drop tank, but the USN figured theirs differently. Figured like an army mission use 400gal (250 internal and 150 drop) less 45gal takeoff and climb to 5000ft, 93gal for 20 min combat at 25000ft and a 20gal reserve for landing. That leaves 242gal for cruising at 93gph (max cruise) or 2.6hours. About the same as the P-39N at 2.8hrs. Max cruise is not max continuous (normal) which used 250gph at 25000ft, that would give you less than 1hr.

So if all this was true why didn't at happen Expert, why did the US leave their most valuable A6M killer back in the states or used it for secondary roles when quite clearly it would have turned the tide in the Pacific?.

 

[GregP]

I wasn't doing it the hard way, I was using the Pilot's Operating Handbook, which the REAL pilots would have been using, and which YOU should be using, too.

My P-39N POH says full internal fuel is 87 gallons. Could be that later P-39Ns had 120 gal, I won't look it up, but I thought the P-39Q-5 was the one with full internal tanks restored after they had been reduced to 87 gallons. Maybe I disremember and maybe you do. If they DID have 120 gallons, you had 32 more gallons, which would last for 133 more miles at fast cruise, 67 more miles combat range because you have to fly back. Still isn't very impressive and isn't likely to get that way ... they are long out of service and there isn't much chance of them doing better in another war.

The F6F Hellcat was the best fighter, in terms of enemy aircraft shot down, in the Pacific, so I won't really bother with analyzing it; go look at the POH. It stands upon merit. The fact that is WAS the best at shooting down enemy aircraft is no doubt due to the US Navy holding off approving the F4U for carrier operations until the British embarrassed them by approving it for their own carriers, forcing the Navy to "save face" and ALSO use it that way. As a result, the early Corsairs were used from ground bases by the Marines and weren't living in the target-rich environment of a front-line WWII U.S. carrier fighter in the Pacific. In point of fact, the Corsair was also a VERY good fighter and would have held its own or even have been the best had it been deployed at the same time to carriers. Again, it stands upon earned merits.

The P-39 has no such merits in U.S. or British service and thus should be looked at with some scrutiny since it had short-range and didn't prove very good at air comat in U.S. or British service. Now, had we been fighting ourselves over, say, Nebraska, where targets were close and there was gound under the belly, it might have been fine. It wasn't over water at longer ranges. About the ground part, the P-39 didn't do very well in Europe where there WAS ground under the belly. In the ETO, it was removed from service by the British and sent to obscrure low-priority fronts, like North Africa and the Med, where it ALSO didn't do very well. It did OK in Russian service, but that isn't my country and it didn't do well for us.

And, if you use a 110-gallon drop tank, you drop it before combat, so all the extra fuel is dependent upon NOT finding combat. If you are flying P-39s, you are, or SHOULD be, based close to your targets or you won't get there and back. At least with the P-51 in Europe, if they dropped tanks, there was enough range to fight combat and get home even if they DID abandon escort to make it home.

You are beating a dead horse, guy, and it isn't going to get any better.

 

[Milosh]

Now virtually every mission was a drop tank mission so let's use the 110gal external tank most common in the Pacific. And let's go on up to 25000ft in case we meet any Zeros. Start with 230gal (120+110) less the same 20gal for takeoff, 24gal for combat at 25000ft and landing reserve of 10 gal. That leaves 176gal for cruising at 62gph or 2.8hours of cruising time at 276mph or 772miles. Full 20min combat at 25000ft and a 10gal landing reserve.

Are you saying the P-39 went into combat with the 110gal drop tank still attached?

P39FOIC.pdf (zenoswarbirdvideos.com)
P39TOCLC.pdf (zenoswarbirdvideos.com)

 

[Shortround6]

It also tends to gloss over details.

If you want to use 95% of the gross weight for the performance, fine use it.
BUT make sure the plane you are comparing to is also at 95% and not 100-102%
The P-39N will still beat the F6F-3, just not by as much.

Lets also consider than some of the P-39Ns (the early ones) were delivered with 87 gallon fuel tanks. There was no just fill them up with 120 gallons internal fuel for certain missions.
Later P-39Ns got the 120 gallon fuel tanks restored and some of the ones in the field were refitted.
Part of the reason for this was to get rid of the weight of the self sealing fuel cells holding the last 33 gallons.
You also don't "just" add drop tanks and presto-chango get quite the boost in range you are calculating. Just adding the 75 gallon tank cost the P-39Q 2-5 gallons in climb to height. Adding another 210-225lbs might cost a few more gallons just for the climb.

and then we have the HUGE problem of the P-39 having no combat power rating at 20,000ft. It doesn't even have a full military power rating. Sure you can run it at 3000rpm but the supercharger will NOT supply even the 44.5in of MAP for military power. The engine can only make about 880-885 hp at 3000rpm. This is the big reason it has such good range at 20,000ft.
The engine isn't making any power. Even worse at 25,000ft.

It doesn't matter how much fuel you can strap underneath. What matters is trying to fight on internal fuel (minus warm up and take-off) and then how much fuel is left in the internal tanks for the trip home. You don't fight with drop tanks attached ( well the Japanese did but..........)

At 25,000ft the P-39 has about 725hp available running at 3000rpm and wide open throttle.

I would also like to see the Flight operation instruction chart for the P-39 with the 110 gallon tank attached.

P-39Q-1 with the gun pods could only do 267mph true at 25,000ft with the tank attached at 2600rpm and wide open throttle.

I would like to know how or why the F6F-3 used up 45 gallons getting to 5,000ft. Corsair with basically the same engine only used up 22 gallons to take-off and climb to 5,000ft with a gross weight of 14,200lbs.

 

[Milosh]

Weight and Balance chart for the P-39Q, P39WBC.pdf (zenoswarbirdvideos.com)

 

[nuuumannn]

And let's go on up to 25000ft in case we meet any Zeros.

Actual fly-off tests between A6Ms and P-39s proved that anything above 15,000 feet and the P-39 is outclassed by the Zero. Trials using a P-39D against a Zero 21 in August 1942, admittedly an earlier model than the 'N although the 'D model was what was on the frontline at the time, shows that anything above 12,500 feet and it is left behind. During this particular fly-off, the trial had to be called off because the P-39 was low on fuel, and that was during a trial fly-off under controlled conditions. During similar fly-offs with F4U, F4F, P-38 and P-51, no other aircraft ran out of fuel.

The F6F however during later trials against a Zero 52 in 1944 proved that above 14,000 feet it was superior in every way, below that height up to 9,000 feet the Zero was faster, but between 9 and 14,000 ft the F6F gradually caught up. The F6F-5 model however was superior in speed to the Zero 52 at all altitudes.

No comparison between the F6F and the P-39 as combat aircraft, to be honest. One is clearly superior to t'other, and their relevant combat histories prove that beyond doubt.

 

[Shortround6]

The F6F-3 could also use it's full power with less chance of cooking the engine on a hot day.

The tests for the P-39N were done on two days, one a bit hotter than a "standard day" temp was about 39 degrees F at 11,000ft when the "standard" called for 19.8.

However the 2nd test report on the same airplane was done on a day when the outside temp was -12 degrees C (10.4 degrees F) at 12,000ft and the plane was judged not acceptable as the estimated temperature on a "hot day" would have been 152 degrees C (305.6 degrees F).
The engine was running about 10 degrees C cooler than the earlier test.

WEP isn't much use if you can't use in the tropics or dessert conditions "Hey, Germans, could you only please attack just about at dawn (coolest part of the day) so our engines won't overheat trying to climb up for the intercept, please, please?"