Dynamic Explorations of a TiltWing Aircraft Transitioning from Conventional to Hovering Flight

Overview

Abstract

Urban air mobility promises short, on demand, flights within urban city-scapes, bypassing congested highways and city roads by taking to the air. To be practical, one requires efficient vertical takeoff and landing aircraft that can transition from thrust-borne flight to more efficient lift-borne flight.  Electric propulsion and more specifically distributed electric propulsion offers a growing number of aircraft classes and configurations. The tiltwing class of aircraft consists of vehicles with the ability to rotate the wing and propulsion system as a unit a full 90 degrees from the standard fixed wing configuration to one in which the wing and thrust axis become perpendicular to the body axis. Such thrust vectoring provides the thrust-borne and lift-borne capabilities to allow both VTOL and conventional flight operations.

While hover and conventional flight regimes are generally well understood, transitioning maneuvers are a relatively new and challenging regime in which to fly the aircraft.  This is complicated by the interaction of the propeller slipstream and the broad range of angles of attack that may be experienced by the wing. Using historical wind tunnel data, we develop an analytic model of the wing-propeller combination that effectively captures the interaction of the wing with the propeller slipstream, most notably the reduced effective angle of attack and increased dynamic pressure. Using this wing-propeller model, we explore the nature of dynamic transitions for a tiltwing aircraft.  Dynamic visualization is used to help understand key features of these transitions.

Brief Biography

John Hauser received the BS degree from the United States Air Force Academy and the MS and PhD degrees from the University of California at Berkeley, all in Electrical Engineering and Computer Science. Between his periods of education, he flew Air Force jets throughout the United States and Canada participating in active Air Defense exercises. In 1989, he joined the Department of EE-Systems at the University of Southern California as the Fred O’Green Assistant Professor of Engineering. Since 1992, he has been at the University of Colorado at Boulder in the Department of Electrical, Computer, and Energy Engineering. He has held visiting positions at many places including University of Padova, Caltech, Instituto Superior Tecnico in Lisbon, Lund Institute of Technology, and Ecole Superieure d’Electricite. He received the Presidential Young Investigator award from the National Science Foundation in 1991.

John Hauser’s research interests include nonlinear dynamics and control, optimization and optimal control, aggressive maneuvering for high performance motorcycles and aircraft and other vehicles, and dynamic visualization. Recent work has focused on the development of optimization (and optimal control) tools and techniques for trajectory exploration with an eye toward characterizing the trajectory space (with limitations) of highly maneuverable nonlinear systems. This work finds application in the control of highly configurable UAVs (with propulsion vectoring) and in the analysis of racing motorcycles.