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The Japanese Quiet Short Take Off and Landing experimental aircraft named ASKA was developed and flight tested during 1977 till 1989. The control system hard and software were examined by the functional mock-up with using the actual hardware. The small longitudinal limit cycle was observed in the closed loop test when the Pitch Control Wheel Steering software was on in the mock-up testing. In this paper, first, the method to analyze and to expect the limit cycle based on the describing function was shown. The limit cycle was induced due to the nonlinearities in the automatic control mechanism. The nonlinearities in the hardware were examined to make the model to simulate the system on the computer. The method was shown effective to predict the limit cycle in the mock-up. Second, with using the flight measured dynamics, the limit cycle was concluded as on border line between existing and not, which coincides with the actual flight result.

The four engined Upper Surface Blowing (USB) STOL research aircraft ASKA was developed by National Aerospace Laboratory of Japan and has been in the flight test phase to provide various kinds of flight data. The position error in airspeed and angle of attack is discussed, and the low speed performance demonstrated in the flight test is provided by the figures of lift/drag coefficient curves and V-Gamma plot. Several indications of powered lift and dynamic stability derivatives obtained from the V-Gamma plot are discussed. The flight measured pitching moment shows the distinctive features such as pitch up tendency. The wing-body pitching moment and the downwash angle are analyzed from the flight load measurments of the horizontal tail. The ground effect of the ASKA is also presented quantitatively in this paper.