Correlation of Experimental and Theoretical Steady-State Spinning Motion for a Current Fighter Airplane Using Rotation-Balance Aerodynamic Data

Abstract : An analytical study has been conducted to determine the usefulness of rotation-balance aerodynamic data in calculating the steady-state spin motion of a current fighter aircraft configuration. The analysis utilizes a nonlinear six- degree-of-freedom digital computer program to generate time histories of airplane spinning motion. Three aerodynamic data models were formulated and used in the spin analysis. The first model represents the conventional use of static and forced-oscillation data; the second model uses the static and forced- oscillation data but restricts the forced-oscillation data to that component of the total angular rate that is oscillatory; and the third model incorporates rotation-balance data from model 2 and restricts the rotation-balance data to that component of the total angular rate that is steady state. The results indicate a significantly different motion resulting from the three aerodynamic data models when compared to each other and to full-scale flight test steady- state spin motions. The motions produced by the rotation-balance aerodynamic model more closely simulate the motions exhibited during the flight tests.