A flight investigation has been conducted of an automatic gust-alleviation system designed primarily to improve riding comfort in rough air.nThe gusts were sensed by a vane located on a boom ahead of the airplane. The wing flaps moved in response to the vane in such a way as to counteract the change in wing lift due to the gust and a portion of the elevator moved to counteract pitching moments due to flap deflec¬tion. In the final configurations, inboard portions of the wing flaps also moved in such a way as to counteract the change in angle of attack at the tail due to the gust.nThe results indicate alleviation of normal acceleration of up to about 60 percent at the natural frequency of the airplane (0.6 cycle per second) and about 40 percent at 2 cycles per second. A further increase in riding comfort was achieved by a simultaneous alleviation of pitching velocity. For this particular airplane, gusts having fre¬quencies greater than 1.5 cycles per second at a speed of 130 knots had little effect on riding comfort. Brief tests were also made of a con¬figuration intended for reducing structural loads and of a configura¬tion utilizing an accelerometer as the gust sensor. The gust allevia¬tion capabilities of these configurations were somewhat less than that of the optimum configuration with vane-type gust sensor.
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