Retrospective essay on nonlinearities in aircraft flight control

A development history is presented of treatments of the peculiar and potentially destructive behavior manifested in aircraft nonlinear mechanics. With the exception of limiters and such mechanical features as preloading, the effort to define and employ beneficial nonlinearities has been largely unsuccessful. No general theory of nonlinear systems is possible, and analytical methods for the treatment of specific nonlinear effects have undergone very meager development. Discrete nonlinearities are noted to be essential between system architectures, in envelope restrictors, and in redundancy management. (O.C.)