ORIGINAL: Lance Campbell

I'm knee deep in the installation of the turbines into my scratch built SR-71, and I've got a question to pose.

I know that if I were doing, say a twin B-25, with props pulling, I'd shim the engines with 1-2 degrees of down and 1-2 degrees of inward angle on the engines. Kind of a 'toe in' approach on the engines, if you would.

Now, ponder the SR-71 with turbines mounted very far forward in the nacelles. Tailpipes are 39 inches long. When standing aft of the plane, do you think you would want the pipes to:

A. Exit a bit down from center line = down thrust
B. Pipe exits pulled together 1-2 degrees
C. Pipe exits pushed out 1-2 degrees
D. Pipe exits straight back on centerlines
E. Any combination of the above
F. I have no idea, but think they should be pointed somewhere towards the back of the plane.

Any thoughts would be appreciated.

Lance