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endurance record. From his model build- ing experience he gained great insight into the importance of propeller design on air- craft performance. After graduating from high school he enrolled in Catholic University where he majored in aeronauti- cal engineering, graduating number one in his class. After graduation he took a job with Hamilton Standard in East Hartford, CT. His first assignment was in the pro- peller performance section of the aerody- namics division.

Charles Kaman became attracted to helicopters after witnessing the flight of a Sikorsky helicopter in nearby Bridgeport, CT. When Hamilton Standard formed a new department to do design work for Sikorsky in 1943, Charles was selected to head up the aerodynamics (Kaman, 1985). While working for Sikorsky, he became interested in reducing helicopter control forces and increasing stability.

This was

not part of his assignment, so he worked on the problem on his own time and eventual- ly developed his patented servo flap control


Above: A K-225 is shown flying in Washington, D.C. over the National Mall. The passengers in the back are Senator Brian McMahon and Congressman Tony Sadlack. Left: Charles Kaman (center) is pictured with Herb Twinning (left) and Bill Murray (right) refining his servo flap rotor head. Photos: Courtesy of Kaman Aerospace

system. Unlike most helicopters, which change blade pitch by rotating the entire length of the blade at the blade root, the servo flap control sys- tem uses a small aileron type wing attached rough- ly three quarters of the way out on the trailing edge of the blade to fly the blade into position. Changing the blade pitch at the root takes strong control forces which often require hydraulic assis- tance and create large flight control loads and strong vibrations. The servo flap control system only requires small control forces to move the rel- atively small servo flap, the flap then moves the rest of the blade eliminating the need for strong con- trol forces and decreasing the large loads on the flight controls and vibration levels. This was a radical idea and in order to get any support for it


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