Research Programs

Flight Dynamics and Controls

Virtual simulator of a tiltrotor on the runway

Flight dynamics and control for rotorcraft pose unique challenges due to the inherent instabilities of the flight vehicle, the aerodynamic and mechanical complexity of the system, and the operational environment, which is often obstacle-rich with poor visibility at low altitude. As new designs emerge, such as individual blade control (IBC), on-blade control (OBC), and variable rotor speeds, it is essential that control of flight and the capabilities of the pilot be integrated in the design process. Fundamental research is conducted to address the implications of higher-bandwidth control arising from IBC and OBC concepts, mitigation of dynamic effects resulting from rotor speed changes, and the reduced control response inherent to larger rotorcraft. This research will improve the predictive models for rotorcraft dynamics and will develop the tools needed to ensure desirable handling qualities.

Current flight dynamics and controls research focuses on the handling qualities of large hovering rotorcraft, particularly of a large tiltrotor aircraft such as the Large Civil TiltRotor -2 (LCTR2). The size of these aircraft pose design and operating challenges that begin with the location of the cockpit very far ahead of the aircraft center of gravity. A new set of design guidelines must be developed.

The Vertical Motion Simulator (VMS) at Ames Research Center provides an excellent facility for investigating flight dynamics and controls issues of concept aircraft. The large travel motion platform provides a motion cueing environment over the response frequency range most important to human-in-the-loop control, particularly in the hover environment. The reconfigurable simulator cockpit provides for controls and display design research within the context of a large transport aircraft. A computer graphics image system presented through a wide field of view, multi-window cockpit visual system completes the realistic operating environment simulation necessary for handling qualities investigations in hover.

VMS cockpit view

Investigations of handling qualities requirements for large tiltrotor aircraft began with an investigation of rotorcraft control system stability and phase margin requirements in 2007.  This was followed in 2008 by a study of pitch roll and yaw response requirements in hover.  A 2009 VMS entry will expand the operating condition beyond hover to modest forward and sideward speeds and will investigate use of tiltrotor nacelle (rotor shaft) angle movement and parallel lateral rotor cyclic response for low speed control of the LCTR2 aircraft.

Point of Contact

William Decker
NASA Ames Research Center
Moffett Field CA 94035-1000