Download or read book Investigation of Transonic Control Surface Instabilities of a Lifting Body Configuration written by Robert L. Goldman and published by . This book was released on 1968 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental wind tunnel investigation has been performed to determine the important aerodynamic and structural parameters contributing to transonic control surface instabilities and related unsteady transonic flow phenomena on the lower flap and bottom surface of a lifting body configuration. The tests were conducted on a modified 0.2 scale model of the Air Force's SV-5 in the AEDC 16-foot Transonic Propulsion Wind Tunnel Facility. The model, its flap elastically restrained in rotation by an interchangeable flexure spring, was tested at Mach numbers ranging from 0.80 to 1.40 and at Reynolds numbers from 4,000,000 to 14,000,000 based on model length. Measurements of steady and unsteady pressures and flap hinge moments and high speed schlieren motion pictures were used to assess the character of the test observations for four different flap natural frequencies, at vehicle angles of attack between 10 deg and 30 deg and over a range of flap deflections from 0 deg to 45 deg. The results indicated the existence of a self-excited control surface instability. The response was related to the formation of shock waves in the vicinity of the flap and appeared to fit the classical descriptions of transonic buzz. When an instability did not occur the flap oscillations became random and non-divergent. The sensitivity of this type of response to pressure disturbances in the boundary layer seems to place these excitations in the buffet category. (Author).