P-38 vs F-82: A Question of Counter Rotation

[Dan K]

Hi all. Here's a question for the P-38 experts that has puzzled me for a while.

Retired Col. John Sharp, former CO of the 4th Night Fighter Squadron during the Korean Conflict, wrote the following around 1974 concerning the F-82G:

The airplane flew like no other fighter. It far surpassed the performance of the P-51 and P-38. Anyone who flew the P-38 knew the comfort of flying the counter rotating propellers--no torque, no trim changes during maneuvers, etc. The big drawback to the P-38, however, was that the props rotated "out" creating a terrible torque problem and trim change during single engine operation. The F-82 props rotated "in" causing the torque or "P" factor if you prefer to work to LIFT the dead side. We could feather one of these engines at high speed with little or no trim change... On several occasions we would fly tight formations, feather one engine on command, continue as if we were single engine fighters and perform formation acrobatics."

My question is this: If such a dramatic single-engined advantage lay with having counter rotation inward, can anyone accurately explain why almost all of P-38 production had the props rotate out?

[51fixer]

Hi all. Here's a question for the P-38 experts that has puzzled me for a while.

Retired Col. John Sharp, former CO of the 4th Night Fighter Squadron during the Korean Conflict, wrote the following around 1974 concerning the F-82G:

The airplane flew like no other fighter. It far surpassed the performance of the P-51 and P-38. Anyone who flew the P-38 knew the comfort of flying the counter rotating propellers--no torque, no trim changes during maneuvers, etc. The big drawback to the P-38, however, was that the props rotated "out" creating a terrible torque problem and trim change during single engine operation. The F-82 props rotated "in" causing the torque or "P" factor if you prefer to work to LIFT the dead side. We could feather one of these engines at high speed with little or no trim change... On several occasions we would fly tight formations, feather one engine on command, continue as if we were single engine fighters and perform formation acrobatics."

My question is this: If such a dramatic single-engined advantage lay with having counter rotation inward, can anyone accurately explain why almost all of P-38 production had the props rotate out?

I believe it had to due with airflow issues that created turbulence that affected how the aircraft flew.
By rotating the engines outboard they improved that but made single engine ops more difficult.

Rich

[bluehawk15]

That's also what I had heard, that the inward rotation caused "burbling" over the elevator and caused control issues. I think it might have lead to the crash of one of the early prototypes which had inward rotation.

[leo]

Also disturbed the airflow at the wing/center pod junction, adding to the turbulence. Supposedly the fix was changing the rotation and redesigning the wing fillets. I have read where some engineers felt the fillets were the real fix and they ultimately could have gone back to an "in" rotation.

[gregv]

I recall reading a piece on the P-82 development reporting that the first prototype couldn't get off the ground until they reversed the rotation of the propellors; if this is true then maybe they didn't have much of a choice in the direction the props turned, and the positive single-engine characteristics were an unexpected, but unplanned, bonus.

greg v.

[Dan K]

Thanks, gents...the airflow issue makes perfect sense.

Sure am looking forward to the Harkers' F-82 flying acro one day soon.