Project Title:

Wing-Rock Dynamics and Control

09-9316
Wing-Rock Dynamics and Control
Eidetics International, Inc.
3415 Lomita Boulevard
Torrance, CA 90505
T. Terry Ng  (213-326-8228)
ARC -- NAS2-12787

Abstract:

	 Modern fighter aircraft operate with increasing demands for maneuverability and
controllability in order to track targets accurately for gun or missile shots. A
self-induced, limit-cycle oscillation in roll, wing-rock, is sometimes accompanied
by coupled oscillations in yaw that occur near the stall angle of attack. The purpose
of this project was to develop the capability for performing experiments in a water
tunnel to visualize the complex vortex flow fields of aircraft-like models undergoing
oscillations in roll. A forced-oscillation-in-roll apparatus was developed. The effects
of sweep angle, leading edge radius, oscillation amplitude and frequency, and angle
of attack were evaluated. Motion histories of the model and flow response were recorded
on video tape.
	Phase I has demonstrated the feasibility and usefulness of water-tunnel flow visualization
and the forced-oscillation rig in investigating dynamic behavior such as wing-rock.
By carefully matching the frequency and amplitude of oscillation, the flow of a forced
wing oscillation closely resembles that of natural wing-rock. A forced oscillation
rig should also be more convenient to use in many experiments because of the readily
available phase reference from the forcing signal. Furthermore, wing-rock frequency
and amplitude are dependent on model parameters such as moment of inertia and bearing
friction; this often makes comparison between different experiments difficult. With
controlled oscillation, matching between two different models or model and actual
vehicle is 
more achievable.

Potential Commercial Application:

Potential Commercial Application: Applications could be as an alternative control
system for new airplanes or, possibly, as a retrofit to existing aircraft. This study
also demonstrated the value of water tunnels as a research tool.