Turbulence upset and other studies on jet transports.

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Abstract
An analytical computer simulation including coupling of control surface motions with dynamic stability modes and complete-airplane aeroelastic response in atmospheric turbu- lence is presented. Comparisons with the flight records recovered from a wrecked jet trans- port demonstrate the ability to simulate characteristics of catastrophic upsets of commercial transports in severe turbulence. Further application predicts an unusual buffet phenome- non. A digital computer automatically mechanizes an analog computer for the complete simulation. Nonlinear aerodynamics allows wing and stabilizer stall; time-dependent co- efficients 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 sub- sonic speeds. New results characterize a gust-load factor which improves this method of ac- counting for unsteadiness arid compressibility. Revised design criteria, including cou- pling with control systems and pilot response characteristics, as well as a statistical re-evalu- ation of gust-load data, are possible future needs.

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