Business Jet Fly-by-Wire Control Laws Handling Qualities Flight Test Assessment

Fly-by-wire control laws for a business jet were developed and a handling qualities assessment flight test was conducted on the Calspan Variable Stability System Learjet-25. The control laws, which provide a blended normal acceleration and speed (nzu) command response type in the longitudinal axis and a stability axes roll rate and sideslip (p-β) command response type in the lateral/directional axes, were optimized to meet Level 1 requirements for a comprehensive set of stability, handling qualities, and performance specifications. The control laws were evaluated in flight by U.S. Air Force Test Pilot School and Textron Aviation test pilots using a series of handling qualities demonstration maneuvers, including pitch and roll capture and tracking tasks and an offset landing task. Quantitative performance metrics were collected, in addition to pilot handling qualities ratings and comments. Several modifications were made to the control laws based on initial pilot comments and ratings. The final results show that the optimized fly-by-wire control laws provided assigned Level 1 handling qualities for discrete tracking and offset landing tasks.