Downwash Measurements on a Pitching Canard - Wing Configuration

• Main Author: Burkhalter, John E
• Format: Report
• Language: English
• Subjects: AERODYNAMIC CONFIGURATIONS; AERODYNAMIC FORCES; AERODYNAMIC LIFT; Aerodynamics; AIRCRAFT; AIRFOILS; ANGLE OF ATTACK; CANARD CONFIGURATIONS; CIRCULATION; DELAY; DOWNWASH; EXPERIMENTAL DESIGN; FLOW FIELDS; FORWARD AREAS; GRAPHS; HISTORY; LIFT; LIFTING SURFACES; MANEUVERABILITY; MEASUREMENT; OPTIMIZATION; OSCILLATION; PE61102F; PITCH(MOTION); PIVOTS; TEST METHODS; TIME LOG; UNSTEADY AERODYNAMICS; UNSTEADY FLOW; WIND TUNNEL MODELS; WIND TUNNEL TESTS; WING BODY CONFIGURATIONS; WINGS; WUFJSRL2307F138

Experimental wind tunnel tests were conducted using a splitter plate model of a two wing configuration oscillating through an unsteady pitch maneuver. Of primary interest were measurements of circulation lag on each wing and the downwash on the aft wing due to the forward wing. It was found that circulation lag associated with oscillating wings is independent of externally induced downwash flow fields but is dependent on the location of the pivot point for the wing or airfoil section, the starting and ending angle, and the angle of attack history. Downwash from a forward wing on an aft lifting surface can make a significant contribution to the lifting properties of the aft wing. The magnitude of these downwash forces are dependent on the forward wing normal force magnitudes and may enhance or degrade the potential of an aft wing to produce lift. The downwash induced in this case, however, is not synchronized with the circulation lag associated with the forward wing but the shift in the downwash curve is more or less synchronized with the circulation lag associated with the aft wing. Consequently a forward wing producing positive lift can produce upwash on an aft wing increasing its potential to produce lift. Enhancement of maneuverability for an aircraft can also be increased by placing the forward canard above the main wing lifting surface.