Author: Patrick J. Peters

Publisher:

Published: 1997-03-01

Total Pages: 147

ISBN-13: 9781423567370

This report presents the results of an investigation into the effects of elevator rate limiting and stick dynamics on longitudinal pilot-induced oscillations (PIO). A simulation study was conducted to prepare for the flight test, but also to gain insight into the effects of rate limiting and stick dynamics. Due to the non-numerical nature of the simulation results, a flexible three-phase flight test plan was developed, first varying the rate limits, then varying the stick dynamics, and finally flying a matrix determined in the first two phases. There were three major conclusions. First, the offset landing task flown was insufficient to consistently uncover handling qualities deficiencies of the aircraft configuration flown. Second, rate limiting did not necessarily cause PIOs. At very low rate limits the problem was lack of pitch response, not PIO. Any oscillations were very low frequency and small in amplitude. Third, for this configuration and task, variations in stick spring constant and natural frequency had negligible effect on the performance of the system with respect to assigned PIO and Cooper-Harper ratings. These conclusions are specific to this system and may not apply to all aircraft, especially aircraft where PIO tendencies are driven by much higher rate limits.