Turbulence upset and other studies on jet transports

J. HAAS
1966 3rd Annual Meeting   unpublished
An analytical computer simulation including coupling of control surface motions with dynamic stability modes and complete-airplane aeroelastic response in atmospheric turbulence is presented. Comparisons with the flight records recovered from a wrecked jet transport demonstrate the ability to simulate characteristics of catastrophic upsets of commercial transports in severe turbulence. Further application predicts an unusual buffet phenomenon. A digital computer automatically mechanizes an
more » ... g computer for the complete simulation. Nonlinear aerodynamics allows wing and stabilizer stall; time-dependent coefficients in the equations of motion allow variations in control deflections arid gains, forward speed, and lift due to indicial delay. Compressibility effects indicate that the over-all Prandtl-Glauert correction applied to the incompressible gust-loads formula leads to conservative values of the load factor when compared to those based on the exact theory. Shock-induced stall buffet is not present in all upsets as are the gust-induced oscillations and subsequent incontrollability. Some basic stability parameters are shown to be inadequate at high subsonic speeds. New results characterize a gust-load factor which improves this method of accounting for unsteadiness arid compressibility. Revised design criteria, including coupling with control systems and pilot response characteristics, as well as a statistical re-evaluation of gust-load data, are possible future needs. a b C F 9
doi:10.2514/6.1966-1002 fatcat:2c6bx7xnaje6tmtwdt5jvbztre