Banana Tailed P-38

[Zipper730]

I remember there was a P-38E design that was based around being able to get the plane rapidly out to bases in the Pacific Theater. It was basically proposed as follows

• The aircraft would have floats installed onto the aircraft
  • The aircraft would retain normal landing-gear; they would merely be retracted and the floats attached
  • They would, in addition to being a viable float for takeoff and landing, would also carry huge amounts of fuel
• The aircraft would takeoff on water and fly up to 5000 miles for a ferry flight
• Upon arrival, they would take the floats off, extend the landing gear, and have a viable aircraft

Because of the water's spray, they reshaped the tail and lengthened the aircraft two-eet. The aircraft was built and tested as a prototype, though it was never fielded.

That said, I remember there being some research around the raised tail being used to offer improved mach tuck effects as the tail being raised up would not be affected as quickly by the turbulent flow forming off the wings.

Does anybody have any data as to what became of that?

 

[fubar57]

Fighters and Bombers of World War II

 

[fubar57]

The P-38 "The Fork-Tailed Devil"

 

[MIflyer]

From Warren Bodie's book on the P-38. The idea was to use the floats to enable a nonstop range of about 5000 miles to enable the P-38's to make it to Australia. The Battle of Midway ended concerns about being able to get to Australia.

 

[Zipper730]

M MIflyer ,

Why would they shorten the raised-tail? It seems like it would have been more aerodynamic if one was to have kept it longer. Did it pose a weight penalty?

 

[MIflyer]

According to the book. that first raised tail was for the floatplane idea, to keep the tail out of the spray. To do that they added "stovepipe" sections between the existing attachment point, raising them by 18 inches and extending them by 24 inches. The extension was a result of raising the tail using the existing attachment points.

The later raised tail mod to that same P-38E, 5204, was part of an attempt to address the compressibility problem, and the redesigned the whole aft boom behind the radiators, thus having no need to extend the booms.

 

[Zipper730]

According to the book. that first raised tail was for the floatplane idea, to keep the tail out of the spray.

I understand

To do that they added "stovepipe" sections between the existing attachment point, raising them by 18 inches and extending them by 24 inches.

What's a stovepipe section?

The later raised tail mod to that same P-38E, 5204, was part of an attempt to address the compressibility problem, and the redesigned the whole aft boom behind the radiators, thus having no need to extend the booms.

So it was just unsightly in appearance, but not in function?

 

[fubar57]

If you bothered to read the links you would have found "Wind tunnel tests revealed minimal performance loss. "

 

[MIflyer]

And actual flight tests showed a 1mph decrease in speed.



Well, y'all have fun. I gotta go figure out what is wrong with a mag switch.

 

[Zipper730]

If you bothered to read the links you would have found "Wind tunnel tests revealed minimal performance loss."

I read through the links and found it. I missed it during the first read.

And actual flight tests showed a 1mph decrease in speed.

This seemed to be the result of the original banana floats.

 

[Zipper730]

There's a PDF I'm attempting to attach, if it doesn't work: I'll have to link it manually.

Neither the results of force tests nor observations of the model behavior during tests gave any indication as to whether or not tail buffeting occurred. Figures 29 and 30, which give results of measurements of the wake at the position of the tail, show that with the standard tail position, the tail will come within the wake of the wing and fuselage at high Mach numbers. These results indicate that raising the horizontal tail surfaces 32 inches above the standard position should keep them out of the wake, except for Mach numbers above .0.75 at angles of attack above 2, and should thereby largely eliminate buffeting. Reference 2 makes a similar conclusion Tests were made with the tail altered as shown in figure 31. The model dimensions indicated correspond to raising the tail 32 inches and moving it back 24 inches on the airplane. Figure 32 shows the aerodynamic characteristics resulting from this change. The only effect as compared to the standard tail position was an increase in stability."

 

[Zipper730]

I'm confused about something here: The original Scorpion-Tail/Banana Float indicated a lengthening of 24". The image I put up earlier, and am replacing here (I deleted the earlier one to make for less space) shows a tail-lengthening of 4'0"

Considering the tail was raised 5'6" -- higher than any other variant I've ever heard of, and the tailplane was thinned, I'm curious if this was one additional proposal aimed at increasing maximum mach number?

 

[fubar57]

There were three versions

 

[Zipper730]

There were three versions

And one was simply for a float plane, the other two for increasing max mach number?

 

[MIflyer]

The drawing you posted says 4 inches, not 4 ft.

According to Warren Bodie's book, the tail was raised 16 to 18 inches on P-38E 3204 and extended 24 inches aft for the floatplane version tests. By "stovepipe section" that means that it was as if they disconnected the boom from the tail at the normal separation joint and inserted a section of stovepipe, with the ends cut at an angle so to raise the tail. A side effect was that the tail was extended aft by 24 inches as a result of inserting the "stovepipes."

For the later modification of P-38E 3204, the purpose being to investigate possible fixes for what in reality was a compressibility problem, new booms aft of the radiators were constructed that raised the tail by 33 inches without increasing the overall length of the airplane.

Now the modified RP-38E 5226 "Swordfish" had the center gondola cockpit section extended forward by 30 inches and the aft section extended by 48 inches into a cone thats tuck out behind the center gondola. It was used for dive testing to investigate the compressibility problem.

 

[Zipper730]

The drawing you posted says 4 inches, not 4 ft.

Uh, sorry 'bout that...

I guess it was a scaled model they were evaluating this on

According to Warren Bodie's book, the tail was raised 16 to 18 inches on P-38E 3204 and extended 24 inches aft for the floatplane version tests.

3204 is also 41-1986 right?

By "stovepipe section" that means that it was as if they disconnected the boom from the tail at the normal separation joint and inserted a section of stovepipe, with the ends cut at an angle so to raise the tail.

A literal stovepipe as a fuselage plug?

For the later modification of P-38E 3204, the purpose being to investigate possible fixes for what in reality was a compressibility problem, new booms aft of the radiators were constructed that raised the tail by 33 inches without increasing the overall length of the airplane.

I'm amazed that modification didn't produce aerodynamic troubles.

Now the modified RP-38E 5226 "Swordfish" had the center gondola cockpit section extended forward by 30 inches and the aft section extended by 48 inches into a cone thats tuck out behind the center gondola. It was used for dive testing to investigate the compressibility problem.

And I guess that had to do with flow separating behind the gondola?

 

[wuzak]

A literal stovepipe as a fuselage plug?

Not literal stovepipe, I'm sure.

 

[MIflyer]

It was literal stovepipe, made out of refractory brick. Or maybe not.

The Swordfish extended the center gondola/cockpit under the theory that it was airflow off the center was disturbing the tail sirfaces and causing what became known as compressibility tuck. That was not the problem and the flaps that moved the center of pressure back forward was the answer. But they did say that was the best diving of all the P-38's, so much so that Lockheed bought the airplane from the government to use for tests of F-90 models. After the F-90 tests, the Swordfish was sold to the only user of the F-90, The Blackhawks.

 

[Zipper730]

By the way how much of an increase in mach number did the recovery flaps provide?