Accession Number:

ADA218244

Title:

A Video-Based Experimental Investigation of Wing Rock

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF SYSTEMS AND LOGISTICS

Personal Author(s):

Report Date:

1989-08-01

Pagination or Media Count:

261.0

Abstract:

This research developed a definitive theory on the cause of wing rock. The study was based on dynamic measurements in both a water tunnel and a wind tunnel on a sharp-edged delta wing with an 80 deg. leading-edge sweep angle. Experimental data were compared with analytical results from a mathematical model and a fourth order Runge-Kutta integration. In the water tunnel tests, conducted at alpha 35 deg. and Reynolds numbers from 30000ft to 75000ft, the movement of the leading-edge vortices and the model motion were simultaneously tracked and analyzed using a video-based motion analysis system, ExpertVision. The initial phase of the study validated ExpertVision accuracy using stationary and forced oscillation tests on 70 deg. and 80 deg. delta wings. Vortex trajectory, core velocity, and burst point results from stationary tests were in good agreement with published data. Forced oscillation tests proved that ExpertVision could simultaneously track and analyze the movement of leading-edge vortices and model motion. Wing rock is caused by the dynamic behavior of the leading edge vortices. The alternate lift-off and reattachment of the vortices generate an asymmetry in vortex lift and cause changes in rolling moment that initiate and sustain roll oscillations. Wing rock dynamics were significantly different water tunnel and wind tunnel experiments. Apparent mass terms must be included in the equations of motion when converting water tunnel acceleration data to rolling moment coefficients with no apparent mass correction, C sub l calculated from accelerations in the water tunnel were about 15 times greater than those from the wind tunnel. Theses.

Subject Categories:

  • Aerodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE