Transition Strategies for Tilt-Wing Aircraft

Abstract

Tilt-wing aircraft promise to combine cruise efficiency with vertical takeoff and landing capability. However, this introduces the complex but crucial transition flight phase, which is not yet well understood regarding aerodynamics and flight dynamics. To better understand the aircraft’s dynamic behavior within this flight regime, this paper analyzes the longitudinal tilt-wing transition, considering various operational strategies for the maneuver. The analysis is based on an optimal control approach where the dynamic control problem is transcribed into a nonlinear programming problem. The developed framework allows for successfully exploring different transition strategies by adapting constraints and objective functions. Compared to the results of static trim analyses, the phenomena of transition folds are attenuated in the dynamic investigation due to inertial effects. Furthermore, the backward transition maneuver from cruise to hover flight proves to be more challenging from a flight physics perspective because of high effective angles of attack and requires upward motion if flow separation is to be avoided