Accession Number : ADA115549

Title :   Calculating Aircraft Controllability Quality.

Descriptive Note : Master's thesis,


Personal Author(s) : Yarger,John M

PDF Url : ADA115549

Report Date : Dec 1979

Pagination or Media Count : 153

Abstract : A quantitative measure of linear system controllability quality was developed, implemented in a software program, and demonstrated through a preliminary evaluation of an experimental aircraft flight control system. A linear state space representation of aircraft perturbation motion was used as the differential constraint equation for a quadratic cost functional which minimizes the control energy required to reach a specified final state. The singular value decomposition of the controllability Grammian, which appears in the solution to this optimal control problem, yields a unique time-varying, orthogonal set of basis vectors which are ranked by the control energy required to move the linear system along each vector. The experimental flight control system consists of variable incidence wingtips acting as elevons and rudders, used on a supersonic-cruise light-weight fighter. The evaluation included both comparison of basis vector sets between baseline and modified aircraft and direct comparison of the control magnitudes required to reach sample final states. Results show the experimental controls are unsuitable due to: (1) poor longitudinal and lateral control power, (2) no yaw/rudder control available due to symmetry restrictions in the linear aerodynamics software.

Descriptors :   *Aerodynamic stability, *Flight control systems, *Computer aided diagnosis, *Aerodynamic control surfaces, Computerized simulation, Computer programs, Linear systems, Optimization, Control theory, Pitch(Motion), Yaw, Drag, Numerical methods and procedures, Advanced weapons, Aircraft, Theses

Subject Categories : Computer Programming and Software
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE