The F101 “Voodoo” was a lean mean supersonic jetfighter machine with a nasty pitch-up problem.
Designed by McDonnell in the 1950’s , the F-101 was used by the United States Airforce and the Canadian Royal Air Force. The F-101 saw many unique roles in its 20+ year career. Originally designed to be a fighter-bomber, the aircraft quickly moved on into reconnaissance and continued to serve as a “utility infielder” of sorts with interception duties and a training role. Unfortunately, despite some of its advanced capabilities and its speed (for the time), there was a nasty little aerodynamic issue which caused the aircraft had a serious “pitch-up” problem that while improved, was never fully fixed.
Pitch-up: What is it?
Pitch-up is a type of aggravated stall that commonly occurs in aircraft of this wing type. An aircraft can stall at any time if the AOA is exceeded. In this case though, pitchup could occur and cause stability issues that actually would lead to a stall. The pitch-up was caused by downwash on the stabilizer during high AOA that causes both a pitch up from the downward force and a reduction in the effectiveness of the stabilizer itself. Essentially, the jet would become unstable.
The pitch-up tendency was actual double wammy against stable flight. If uncorrected, this issue could cause departure from controlled flight. Luckily, the Air Force was aware of these problems and created training videos concerning what needed to be done to correct the issue mid-flight. This video was put together to train pilots how to avoid the envelope where pitch-up was most likely to occur.
Now it’s easy to look back on these early training videos and think how boring it must have been to watch them. But put yourself in the position of the crew for a moment. Here you were about to fly one of the most advanced fighters of the day and you were being told that if you exceed seemingly normal AOA’s, you could depart controlled flight and not be able to recover. It would make me pay attention. That’s for sure!
The F-101 flew with the RCAF and the US Air National Guard until 1982. Canada flew their jet until the F-18 replaced it in the late 1980s.