F-111

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AWARDED    (worth reading)	COMPLETED

This project was a "first of a kind" attempt to drastically change the airfoil, on a  large aircraft, to verify wind tunnel data. The object was to develop airfoils for transport category aircraft. The airfoil we were about to install on this F-111 was very "thick" and had a larger cord than the existing wing. The speeds for which it was designed were around Mach 0.8. (typical airliner speeds) the airfoil, due to its thickness, would allow for a lighter wing structure as well as provide additional volume for fuel. The hope was to have laminar airflow over a large proportion of the wing. We were to modify both wings in order to keep them somewhat symmetrical. The actual test section was on one wing only and it was the only area that also had a lower surface test section. This turned out to be the very most difficult portion of the task. considering that the contour accuracy was to be "the best that could be done" and the smoothness to be at least as good as a Sailplane wing.

Knowing that we could expect anyone to contour and smooth such a large area to the tolerances expected, I decided to build a "dummy" wing. This "Dummy" was built on a metal frame work, covered with sheet metal, representing the underside of the F-11 wing. Onto this we applied Urethane foam - glass - and bondo (r) before starting the serious contouring effort. We planned on bonding the completed section onto the wing  by vacuum bagging it onto the underside and bonding it with epoxy.

It is a longer "Story" than fits here, NASA engineers had bet a case of beer that this could not be done successfully. They clearly wanted us to succeed and helped with suggestions and ideas. But AS YOU CAN SEE,  if you can read upside down, they had their doubts! As it turned out, we did come up with a solution to the problem and only just before the last flights, one small delamination occurred. On a Sunday morning, no safety guys around!, I was asked to make a judgment call: To Fly or Not To Fly. The test Pilot Einar Enevoldsen long retired, is a good friend of mine and the bail out mode on the F-111 had its problems. A tough call to make. Bottom line: I said "GO"  he said "OK" and told the chase aircraft to "stand clear" These were the good old days when reasonable choices were still made by people instead of politicians!

The effort took more than a year. The results, I was told, were well worth the time and money spent. Martha Bohn-Meyer and I co-authored an award winning paper describing the methods used to accomplish the work. Subsequent airfoil testing followed similar methods, developed during this project. The F-14 Variable Sweep Transition Flight Experiment, was just one of them

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