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Winther, B. A.

Publications and source records attributed to Winther, B. A..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Wind tunnel investigation of active controls technology applied to a DC-10 derivative

Application of active controls technology to reduce aeroelastic response offers a potential for significant payoffs in terms of aerodynamic efficiency and structural weight. As part of the NASA Energy Efficient Transport program, the impact upon flutter and gust load characteristics has been investigated by means of analysis and low-speed wind tunnel tests of a semispan model. The model represents a DC-10 derivative with increased wing span and an active aileron surface, responding to vertical acceleration at the wing tip. A control law satisfying both flutter and gust load constraints is presented and evaluated. In general, the beneficial effects predicted by analysis are in good agreement with experimental data.

Winther, B. A.↗
NASA NTRS1979

Demonstration of aircraft wing/store flutter suppression systems

A wind tunnel test program was conducted to demonstrate the active wing/store flutter suppression systems on a lightweight fighter aircraft. The program, completed in mid-1978, included the design, analysis, fabrication, and testing of a scale model. The tests were conducted at the NASA Langley 16-ft Transonic Dynamics Tunnel. Three store configurations were selected for testing. Two of these configurations were deliberately designed to exhibit low flutter speeds with rapid reductions in damping at the incipient flutter condition. After initial tunnel entries, which showed the need for certain improvements in the model and the control system design, substantial increases in the flutter speeds were achieved using both leading- and trailing-edge control surfaces, separately. For the most critical configuration, a demonstrated improvement of 18% and a projected improvement of 29% in the dynamic pressure were achieved.

Hwang, C.↗
NASA NTRS1972

Prediction of unsteady aerodynamic loadings caused by trailing edge control surface motions in subsonic compressible flow: Analysis and results

A theoretical analysis and a computer program have been developed for the prediction of unsteady lifting surface loadings caused by motions of trailing edge control surfaces having sealed gaps. The final form of the downwash integral equation has been formulated by isolating the singularities from the non-singular terms and establishing a preferred solution process to remove and evaluate the downwash discontinuities in a systematic manner. Comparisons of theoretical and experimental pressure data are made for several control surface configurations. The comparisons indicate that reasonably accurate theoretical pressure distributions and generalized forces may be obtained for a wide variety of control surface configurations. Spanwise symmetry or antisymmetry of motion, and up to four control surfaces on each half span can be accommodated.

Rowe, W. S.↗
NASA NTRS1972

Prediction of unsteady aerodynamic loadings caused by trailing edge control surface motions in subsonic compressible flow: Computer program description

A digital computer program has been developed to calculate unsteady loadings caused by motions of lifting surfaces with trailing edge control based on the subsonic kernal function approach. The pressure singularities at hinge line and side edges have been extracted analytically as a preliminary step to solving the integral by collocation. The program calculates generalized aerodynamic forces for user supplied deflection modes. Optional intermediate output includes pressure at an array of points, and sectional generalized forces. From one to four controls on the half span can be accommodated.

Redman, M. C.↗