Accession Number : ADA183138

Title :   Low-Speed Investigations of 'Apex Fence' and 'Cavity Flap' Concepts on a 60 Degree Delta Configuration.

Descriptive Note : Final rept. 15 Mar 85-15 Oct 86,

Corporate Author : VIGYAN RESEARCH ASSOCIATES INC HAMPTON VA

Personal Author(s) : Rao,Dhanvada M ; Hoffler,Keith D ; Mills,Charles T

PDF Url : ADA183138

Report Date : Mar 1987

Pagination or Media Count : 74

Abstract : This report describes low-speed wind tunnel investigations of 'apex fence' and 'cavity flap' concepts applied to a 60-deg. uncambered delta wing/body configuration. The upper-surface apex fences, hinged near the leading edges, are deployed vertically at low to moderate angles of attack (appropriate to approach and landing) to force a powerful vortex pair which augments suction over the forward regions of the wing planform. The resulting nose-up moment is balanced by means of trailing edge flaps, resulting in increased trimmed lift as well as drag for improved short-field landing capability of the tailless delta. The 'cavity flap' is a lower-surface hinged vortex flap whose deflection creates a frontal cavity underneath the leading edge. Above a certain angle of attack the flap vortex fills the mouth of the cavity, which helps the external flow to turn around the leading edge thus reducing the vortex lift at high angles of attack, and b) creates suction over the cavity frontal area which generates a side-force component. The potential of asymmetrically deployed cavity flaps for lateral/directional control at high angles of attack was of interest. These concepts were subjected to low-speed tunnel studies exploring the lee-side flow field through visualizations and pressure surveys, and measuring force and moment characteristics. Results are discussed which verify the basic aerodynamic of these concepts and assess their potential for trimmed-lift increment and roll/yaw control capability.

Descriptors :   *FLAPS(CONTROL SURFACES), *DELTA WINGS, *AERODYNAMIC LIFT, ANGLE OF ATTACK, CAVITIES, FLAPS(CONTROL SURFACES), DEFLECTION, DRAG, FILLERS, VORTICES, DEPLOYMENT, EXTERNAL, FLOW, SUBSONIC WIND TUNNELS, YAW, ROLL, HIGH ANGLES, LEADING EDGES, LOW VELOCITY, WIND TUNNEL TESTS, MOMENTS, TRAILING EDGES, PLANFORM, WINGS, FLOW FIELDS, MOUTH, ATTITUDE CONTROL SYSTEMS, LIFT, TRIM ANGLE

Subject Categories : Fluid Mechanics
      Aerodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE