Improve That Design: How Aircraft Could Have Been Made Better

[jmcalli2]

Nothing supported the drive shaft between the engine and gearbox except the carrier bearing assembly that was situated at the 60" mark, where the two shafts joined.

So, you have no understanding of the structure of the P-39.
So either read up on it or please go to a different topic.

 

[jmcalli2]

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.

So, your argument is the same as the P-51 time warp story.

Entirely in your head.

 

[jmcalli2]

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.


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.

So you didn't bother to read the design analysis I posted hear.

Sorry for your loss.

 

[GrauGeist]

So, you have no understanding of the structure of the P-39.
So either read up on it or please go to a different topic.

You and your smartass comments are growing tiresome.

Any halfwit can look at a P-39's cutaway and see CLEARLY that the driveshaft is NOT SUPPORTED by any other means than the 1) Engine Output, 2) Carrier bearing assembly at the coupling (at the halfway point) and finally, 3) Gearbox situated at the nose. It was a 102 inch spinning shaft - it wasn't going to be attached to anything other than components that required it's energy transfer.

Perhaps you should go look under your car for a rudimentary idea of what the grownups are talking about here, or find a topic better suited to your limited abilities.

 

[XBe02Drvr]

So you didn't bother to read the design analysis I posted hear.

Sorry for your loss.

A couple of the attachments people put up on this thread refused to open on my Android, but I haven't seen anything contradicting what I posted. Explain yourself.

 

[XBe02Drvr]

Yes I really do wonder. Half of them went to the Soviets where they won the war and the other half were used as trainers here.

The P-39 and P-63 did go to war, it's just that the war they seemed to be good at fighting wasn't the war that the US or Commonwealth were fighting.

Yup, we in the west just couldn't come up with a theater of operations suited to the Airacobra's rather limited advantages, so we made trainers out of them.

 

[XBe02Drvr]

Perhaps you should go look under your car for a rudimentary idea of what the grownups are talking about here, or find a topic better suited to your limited abilities.

He probably has a front wheel drive and will miss your point entirely.

 

[nuuumannn]

The Royal Australia Navy wanted to buy helicopters, and then drowned them in specifications to the extent that they were incapable of entering service.

And now we (the Royal New Zealand Air Force) have them!

I have read a few books on the Stirling, and there is no clear answer however most point to the Air Ministry using it to limit the all up weight. Which is rather ironic, considering the plethora of mandatory requirements which drove the weight so high in the finished product.

Part of the problem with the Stirling was that construction of the prototype was begun before trials with the small scale aircraft had been completed, which meant Short didn't foresee that the wing's angle of incidence was too shallow, which meant it would have had an inordinately long take off run fully loaded, so its gangly undercarriage was lengthened to steepen the angle at which the wing began to produce adequate lift to get the thing off the ground.

 

[XBe02Drvr]

Short didn't foresee that the wing's angle of incidence was too shallow, which meant it would have had an inordinately long take off run fully loaded

The commuter airline I worked for had a couple Short SD30s. They were real ground lovers, too. You could tell they were designed and built by shipyard people. The front office was more like a ship's bridge than an airplane's cockpit. Crews called it "the wheelhouse".

 

[nuuumannn]

The commuter airline I worked for had a couple Short SD30s.

I used to know a Short 360 driver who called it the Short Shed.

 

[GrauGeist]

He probably has a front wheel drive and will miss your point entirely.

Damn...didn't think about that.

I figured the lack of reply was because he was trying to find a cutaway where the driveshaft itself was physically bolted to the center frame...

 

[GregP]

Regarding post 912: Hi P-39 Expert.

The F6F flew 66,530 action sorties for the Navy, claimed 5,163 enemy aircraft shot down, and had 2,461 combat losses, only 270 of which were to enemy aircraft. That averages out to one kill every 13 action sorties. It was the first USN fighter to be able to outclimb the A6M Zero and almost turn with one. It was VERY forgiving and was called the Ace-maker. The kill to loss ratio was 19.12 : 1 for air-to-air and 2.09 : 1 overall if you figure in ALL losses, which is not generally done.

The P-39 flew zero action sorties, had no kills, and no losses in US Navy service.

In USAAF service, it flew 30,547 combat sorties, had 14 air kills and 18 ground kills claimed, had handling quirks that made it a plane nobody wanted to fly in combat. It was nicknamed the Peashooter by pilots becasue of its ineffectivness in combat. It had 107 combat losses, but the USAAF doesn't tell us how many were air-to-air and how many were ground. I can't tell you if the losses were air-to-air or total. That averages out to one kill every 955 combat sorties if you use the total and 1 kill every 2,182 sorties if you take air-to-air kills. The kill to loss ratio was .13 : 1 for air kill and .30 : 1 for all kills. I don't know the makeup of the losses.

When I compare 1 kill every 13 sorties to 1 kill every 955 sorties or 1 kill every 2,182 sorties for air kills (for overall kill-to-loss ratio), and 19.12 : 1 for air kill to 0.13 : 1 for air kills, I have a definite preference for which airplane I'd choose to fly in combat. It ain't exactly a tough choice. Give me the Ace-maker every time.

If you can't see a huge difference in that combat performance, you are blind and fail to realize it. That performance was over the entire population of F6Fs in US service and the vast majority of the USAAF P-39s in Pacific service, which is where we mostly used them. So, both are pretty valid statistical comparisons for airplanes in US service in the Pacific. If you can find the numbers for the P-39 in Soviet service that are from a primary source and not some Russian forum with no references to sources, please share them. I can't find them myself to date.

The Soviet Union fought a low-altitude war and had no restrictions on engine boost. That allowed them to get good performance from the P-39 in a very low-altitude environment that happened to be right where the P-39's strength was. The U.S.A. didn't fight in a low-altitude environment that favored the P-39 and didn't get the performance from the P-39 that the Russian got because we flew by a very different book that was effective in the war WE fought.

 

[Milosh]

Not the best. scroll down
The Modelling News: Kittyhawk's new Airocobra makes it's first built up debut...

 

[P-39 Expert]

P39 Expert,

Okay, the P39 versus F6F comparison is really not that good.
A. The P39 wasn't carrier capable, wasn't able to carry the bomb load, nor did it make as many aces as did the F6F.
B. Range?
C. Grumman was known for making great flying planes. Did the F6F have any problems qualifying on the carrier, did the guys complain about it biting them in any manner similar to what the P39 experienced? The F6F was a large plane due to performance requirements as well as carrier operations imposed weight penalties.

Guys have spent a LARGE amount of time on here trying to show you where you are making assumptions that are not correct, or coming to conclusions based on incomplete or incorrect data.

Your ability to ignore facts, or information you don't agree with is TREMENDOUS.

Good luck.

V/R,
Biff

Agree that the Hellcat was a carrier plane and the P-30 was a land based plane. But like most of my assertions this graph is based solely on facts. Nothing but facts from sources like wwiiaircraftperformance.org and AHT. Official tests conducted by the Navy and Wright Field. The P-39N outperformed the F6F by a substantial margin. This is not an assumption but a fact.

Why can't you, like most on this board, just admit that you had not seen the P-39 performance tests on wwiiaircraftperformance.org? Admittedly the information was not posted on the site until 2012. This is well after most all the reference books on WWII fighters were published, including AHT, the William Green books, etc. All the reference material you have seen on the P-39 is basically wrong/out of date based on those tests.

I have made very few assumptions on here, just results of official military tests. The rest of you guys are the ones who deal in heresay, like tumbling, symmetrical airfoils, the driveshaft breaking, ets. That is all based on heresay and conjecture. Go look at the facts.

 

[P-39 Expert]

Regarding post 912: Hi P-39 Expert.

The F6F flew 66,530 action sorties for the Navy, claimed 5,163 enemy aircraft shot down, and had 2,461 combat losses, only 270 of which were to enemy aircraft. That averages out to one kill every 13 action sorties. It was the first USN fighter to be able to outclimb the A6M Zero and almost turn with one. It was VERY forgiving and was called the Ace-maker. The kill to loss ratio was 19.12 : 1 for air-to-air and 2.09 : 1 overall if you figure in ALL losses, which is not generally done. Hellcat was a great plane, the best Navy fighter in WWII.

The P-39 flew zero action sorties, had no kills, and no losses in US Navy service. And the Hellcat had no stats in Army service. What is your point?

In USAAF service, it flew 30,547 combat sorties, had 14 air kills and 18 ground kills claimed, had handling quirks that made it a plane nobody wanted to fly in combat. It was nicknamed the Peashooter by pilots becasue of its ineffectivness in combat. It had 107 combat losses, but the USAAF doesn't tell us how many were air-to-air and how manby were ground. I can't tell you if the losses were air-to-air or total. That averages out to one kill every 955 combat sorties if you use the total and 1 kill every 2,182 sorties if you take air-to-air kills. The kill to loss ratio was .13 : 1 for air kill and .30 : 1 for all kills. I don't know the makeup of the losses. P-39s main use was early in the war when all the US had in combat were P-39s, P-40s and Wildcats. All three of these planes were grossly overweight, fault of the AAF and Navy, not the designers.

When I compare 1 kill every 13 sorties to 1 kill every 955 sorties or 1 kill every 2,182 sorties for air kills (for overall kill-to-loss ratio), and 19.12 : 1 for air kill to 0.13 : 1 for air kills, I have a definite preference for which airplane I'd choose to fly in combat. It ain't exactly a tough choice. Give me the Ace-maker every time. Hellcat was the best navy carrier fighter, but didn't see combat until September 1943, after most of the well trained Japanese pilots had been killed by those early overweight fighters. Hellcat never faced the Japanese first team. I'm not taking anything away from the Hellcat, just proving that the P-39N outperformed the Hellcat by a substantial margin. Do you disagree with the performance graph figures?

If you can't see a huge difference in that combat performance, you are blind and fail to realize it. That performance was over the entire population of F6Fs in US service and the vast majority of the USAAF P-39s in Pacific service, which is where we mostly used them. So, both are pretty valid statistical comparisons for airplanes in US service in the Pacific. If you can find the numbers for the P-39 in Soviet service that are from a primary source and not some Russian forum with no references to sources, please share them. I can't find them myself to date.

The Soviet Union fought a low-altitude war and had no restrictions on engine boost. That allowed them to get good performance from the P-39 in a very low-altitude environment that happened to be right where at the P-39's strangth was. The U.S.A. didn't fight in a low-altitude environment that favored the P-39 and didn't get the performance from the P-39 that the Russian got because we flew by a very different book that was effective in the war WE fought. The vast majority of the P-39s used by the Russians were P-39N/Q models (same plane without wing guns) which were vastly superior to the early D/K/L models. These were not low altitude planes at all with ceilings over 38000ft and the equal of their Luftwaffe opponents at any altitude.

Please expand above.

 

[Milosh]

P-39Q
service ceiling: 34,900 (100fpm)
absolute ceiling: 35,700 (0fpm)

spin tests, Report on Spin Tests, P-39Q (wwiiaircraftperformance.org)

 

[XBe02Drvr]

P-39Q
service ceiling: 34,900 (100fpm)
absolute ceiling: 35,700 (0fpm)

spin tests, Report on Spin Tests, P-39Q (wwiiaircraftperformance.org)

Note: This spin test was conducted with CG well forward (28.8% MAC) of the aft limit (31% MAC) that would be approached by a combat equipped P39 with ammunition expended.

 

[Shortround6]

Agree that the Hellcat was a carrier plane and the P-30 was a land based plane. But like most of my assertions this graph is based solely on facts. Nothing but facts from sources like wwiiaircraftperformance.org and AHT. Official tests conducted by the Navy and Wright Field. The P-39N outperformed the F6F by a substantial margin. This is not an assumption but a fact.

Why can't you, like most on this board, just admit that you had not seen the P-39 performance tests on wwiiaircraftperformance.org?

Facts
1. The P-39N was running clean except for the drop tank shackle (no sway braces).
2. The F6F-3 was running with fuselage bomb rack and "T" braces, also wing bomb rack fairings and sway braces. In Clean condition the F6F-3 was supposed to be good for 321mph at sea level and 384mph at 18,000ft, not the 372mph shown on the chart.
3. The P-39N was running light. 3-400lbs below normal clean gross weight. Reduced fuel?
4. The F6F-3 is rated at full clean gross weight. Full internal fuel.
5. A minor consideration. (sarcasm) the P-39N was running above (well above?) the the AIr Corp standards for cooling temperatures.
6. This P-39N seems to show an amazing deviation from other P-39s. Performance at 5,000ft
.......................................P-39M.........................P-39N........................P-39Q
Weight...........................7430lbs.........................7301lbs.....................7871lbs
Horsepower..................1395.............................1375............................1382
Climb ft/min.................3840..............................4240...........................3770
Speed at 9,500ft..........385.5............................398.4*.........................374
All at 57in MAP and 3000rpm except the speed of the P-39N.
P-39N used 59.8in MAP at 9700ft.

P-39Q speed was at 10,000ft. P-39Q had the under wing gun pods.
Notes the test of the P-39-Q-5 (different pane than above) state that the external gunpods on the XP-63 were worth about 110ft/min climb. This was noted as the test P-39Q-5 engine was not running properly and so could not be compared to the P-39Q-1 test.

Yep, let's pick and choose our facts very, very carefully and then accuse others of being unaware or failing to see the brilliance of the concept.

rapid climb by P-39 ending with overheated engine in tropical/desert conditions. Great way to start combat, engine already cooking itself.

I would really love to see the different P-39 model's performance on a chart as I think this P-39N would be in a class by itself.

 

[GregP]

Regarding post #935 ... I think not. The point was made very clearly.

 

[Shortround6]

I would like to note another "FACT".

The P-39N test was test of a single airplane.

The F6F-3 data is from an Airplane Characteristics and Performance sheet (multiple) used for mission planning.
In other words every plane (or most) in the unit had to meet those numbers. Yes they were based on tests but using best numbers means some planes might not make it home due to running out of fuel.