The reason the p-39 is overlooked is it is very small. There was no growth potential in the airframe. Look at all the different models there were of the P-47, including prototypes. 3 different engines, if you include the P-72, bubble canopy, additional hard points, wet wing and weight reduction on the N.
It was a point defense interceptor, which is why it was mediocre at everything else.
What I find remarkable about the Spruce Goose is that the entire airframe was made from birch plywood (not spruce). I know the British WWII Mosquito fighter/bomber was made of plywood, but the Spruce Goose is a gigantic aircraft with 28,000 HP. That must have been some structural design.
I've heard Tex Johnston tell his story in person about running the P-39 as an air racer in the 1946 Thompson Trophy race. Hell of a story (and story teller)--
Some bits of the story available here-- http://ipmsvagabonds.com/page3/page23/page23.html
Appleseed wrote: The reason the p-39 is overlooked is it is very small. There was no growth potential in the airframe. Look at all the different models there were of the P-47, including prototypes. 3 different engines, if you include the P-72, bubble canopy, additional hard points, wet wing and weight reduction on the N. It was a point defense interceptor, which is why it was mediocre at everything else.
It was roughly the same size as the Spitfire; 34 feet 2 inches wingspan, Spitfire 36 feet 10 inches (the last versions were 40 feet wingspan). The Spitfire was 29 feet 11 inches long, the P39 was 30 feet 2 inches.
Spitfire:
http://en.wikipedia.org/wiki/Supermarine_Spitfire_variants:_specifications,_performance_and_armament
Airacobra:
http://en.wikipedia.org/wiki/Bell_P-39_Airacobra#Specifications_.28P-39Q.29
The Spitfire had about 35 more square feet of wing area, that might have been a result of the different wing designs.
Gary wrote: What I find remarkable about the Spruce Goose is that the entire airframe was made from birch plywood (not spruce). I know the British WWII Mosquito fighter/bomber was made of plywood, but the Spruce Goose is a gigantic aircraft with 28,000 HP. That must have been some structural design.
Allegedly that's what did it in; it became cheaper and lighter to build big airframes out of aluminum, the Goose just wasn't economically feasible. But yes it was a helluva great design.
The entire reason why Hughes build the H-4 was that aluminum was in short supply because of the war. It was effectively a proof of concept design that was not really needed by the time it was finished (a crap ton of Liberty ships where taking care of the issue). Hughes flew it just to show that the design was viable (at least to some point).
mad_machine wrote: look at the size of the wing.. the mechanics probably walked inside and cranked them from the opposite end from the prop
You're probably right. The wing was over 10 feet thick at it's thickest point and had a passage that allowed mechanics to monitor, access, and service the engines in-flight.
I remember seeing a documentary about the Spruce Goose some years ago. The Takeaway was that, although the plane itself wasn't considered successful, the project was an overwhelming success, due to all new control system technology developed to make such a large aircraft fly. Basically, all the large post-war planes were influenced by it.
......and HH made a lot of Cheddar of the tech patents that descended from that project....
Curmudgeon wrote:Appleseed wrote:That makes one wonder why Pratt & Whitney etc didn't do the same for their radials in WW II. It had to have occurred to them... </block-quote Well the Russkies ripped off so much stuff I figured their radials were same as ours. I think the BMW radial was a ripoff.Curmudgeon wrote: Compression releases are common in the motorcycle world. I wonder why the radial engine manufacturers didn't do something similar; on a four stroke the compression release opens the exhaust valve a bit so the engine can be kick started. It seems to me that would have been pretty simple to incorporate into radial engine design, thus negating the need to pull spark plugs etc and would have saved a lot of time.They did. Russian MP-14 radials have a release at the bottom 3 cylinders to drop any accumulated oil.
Curmudgeon wrote:Tom_Spangler wrote: Huh, I never knew the P39 was mid-engine. I have to think it would help with maneuverability, as well, for the same reason mid-engine cars handle like they do. Low polar moment and all that.It seems the P39 was known for being easy to 'flat spin'. The CW at the time was that it did that because of the big ol' engine being in the middle, but I honestly don't see how that could be the reason. There was so much forward thinking in that aircraft... don't get me wrong I loves me some P40, P47 and P51 but I hate the P39 was passed over by its more famous brethren.
Boyington got this start in a P-39.
Did he? I never read his book, but I am pretty sure his first combat was in China and I think they only used P-40's (a plane of similar performance / issues). He was in the Marines and I am pretty sure the Marines never used P39's (they used Navy planes of course).
Point of trivia: P400..... a P39 with a 20mm instead of the 37mm. I think the Brits and Ausi's wanted them that way.
spitfirebill wrote:Curmudgeon wrote:Boyington got this start in a P-39.Tom_Spangler wrote: Huh, I never knew the P39 was mid-engine. I have to think it would help with maneuverability, as well, for the same reason mid-engine cars handle like they do. Low polar moment and all that.It seems the P39 was known for being easy to 'flat spin'. The CW at the time was that it did that because of the big ol' engine being in the middle, but I honestly don't see how that could be the reason. There was so much forward thinking in that aircraft... don't get me wrong I loves me some P40, P47 and P51 but I hate the P39 was passed over by its more famous brethren.
The flat spin characteristic was related to the nose not being ballasted to simulate an ammo load.
That being said, the P39 was passed over because it had poor high altitude performance and a tiny fuel load.
aircooled wrote: Point of trivia: P400..... a P39 with a 20mm instead of the 37mm. I think the Brits and Ausi's wanted them that way.
Until the Brits actually flew them, laughed their asses off, and said "No thanks." Most P-400s ended up going to our USAAF units in the South Pacific. They were pretty much failures because their ceiling was below the typical altitudes the Japanese bombers flew at.
Will wrote:aircooled wrote: Point of trivia: P400..... a P39 with a 20mm instead of the 37mm. I think the Brits and Ausi's wanted them that way.Until the Brits actually flew them, laughed their asses off, and said "No thanks." Most P-400s ended up going to our USAAF units in the South Pacific. They were pretty much failures because their ceiling was below the typical altitudes the Japanese bombers flew at.
Like the Brits that ordered the P-38 without the superchargers and counter rotating props, were warned that wasn't a good idea, and then complained when it performed poorly and turned better one direction than the other?
Those Brits?
Nah, that obviously was a misunderstanding.
Curmudgeon wrote:Appleseed wrote: The reason the p-39 is overlooked is it is very small. There was no growth potential in the airframe. Look at all the different models there were of the P-47, including prototypes. 3 different engines, if you include the P-72, bubble canopy, additional hard points, wet wing and weight reduction on the N. It was a point defense interceptor, which is why it was mediocre at everything else.It was roughly the same size as the Spitfire; 34 feet 2 inches wingspan, Spitfire 36 feet 10 inches (the last versions were 40 feet wingspan). The Spitfire was 29 feet 11 inches long, the P39 was 30 feet 2 inches. Spitfire: http://en.wikipedia.org/wiki/Supermarine_Spitfire_variants:_specifications,_performance_and_armament Airacobra: http://en.wikipedia.org/wiki/Bell_P-39_Airacobra#Specifications_.28P-39Q.29 The Spitfire had about 35 more square feet of wing area, that might have been a result of the different wing designs.
The Allison stymied P-39 development from the start when they took away it's turbo. Allison struggled with two stage, two speed supercharging, which is why the P-38 only worked well with the GE turbos.
The Spitfire was also a point defense interceptor. They were never fighter-bombers or long range escorts, just like the P-39. I'm not bashing Bell's design. They tailored it to an Air Corps request for defense of our coastline during 30's isolationism. Bell did that, and did it well. Once over Europe and the Pacific, the requirements changed.
Until Howard Hughes' death, the Spruce Goose was maintained in flyable condition. The props were turned every day. Fluids were checked and changed at regular service intervals. The reason Hughes flew the plane was to silence critics who accused him of taking the government's war money and producing nothing. So he flew his prototype to prove the viability of the design.
Actually, he was only scheduled to do some taxi and engine runup tests that day. Guess he got a little carried away...
Curmudgeon wrote: Early radials were known as 'rotaries' because the crankshaft was bolted to the airframe and the crankcase spun around it, thus eliminating the need for a power robbing flywheel. The carburetor fed through the center of the crankshaft.It is really weird to see one running, it messes with your head. https://www.youtube.com/watch?v=CYc-H8Wg-MQ
Unfortunately, all that inertia also meant the aircraft turned really well in one direction but not the other. For instance, the Sopwith Camel turned slowly to the left but could turn to the right faster than any of its contemporaries
Yeah, that's why the design wasn't used for long. The 'gyro' effect was just too hard to overcome.
The P39 was designed as an interceptor not a dog fighter so no wonder it didn't do well against the Zero or ME109. It also got a bad rep when those P400 ended up in the south Pacific and were used because there wasn't anything else available at the time. When used correctly of really used so that they did what they did best they performed well. During the Guadalcanal air battles they were thrown in to help the F4F's of the Marines & Navy to defend the island. They lost to the Zero. Later when the P38 showed up the P39 & P400 were used as ground attack planes and they shined at this. Low altitude where the Allison ran well and the 20 MM or 37 MM gun was effective when it was used against ground targets, ships, etc.
In reply to jimbbski:
The Soviets used the P-39's as ground attack fighters IIRC. EDIT: Evidently the previous statement is a myth, they didn't really need a high altitude fighter so it worked for them.
yamaha wrote: In reply to jimbbski: The Soviets used the P-39's as ground attack fighters IIRC. EDIT: Evidently the previous statement is a myth, they didn't really need a high altitude fighter so it worked for them.
The high altitude role was mainly bomber protection. Since the Russians never produced a decent heavy bomber in WWII.....
Jerry From LA wrote: Unfortunately, all that inertia also meant the aircraft turned really well in one direction but not the other. For instance, the Sopwith Camel turned slowly to the left but could turn to the right faster than any of its contemporaries
This is a great video that shows the effects of the rotary:
https://www.youtube.com/watch?v=j6PnKUEFX8g
The weird idle (and rockin' and rollin') is the result of using ignition interruption as a way controlling power. In other words, the engine is always at full throttle, they just cut of cylinder ignitions to slow it down.
In reply to aircooled:
Very cool video- with a Spitfire flying with a Sopwith Camel.
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