Title

Investigations of Describing Function Technique

Date

1966

Index Abstract

Coming Soon

Photo Quality

Not Needed

Report Number

AFFDL TR 65-137

Creator

Graham, Dunstan

Hofmann, Lee Gregor

Corporate Author

Systems Technology, Inc.

Laboratory

Air Force Flight Dynamics Laboratory

Extent

110

Identifier

AD0631314

Access Rights

Distribution of this document is unlimited

Distribution Classification

1

Contract

AF 33(615)-1474

DoD Project

8219

DoD Task

821904

DTIC Record Exists

No

Distribution Change Authority Correspondence

None

Abstract

Three problems were chosen so as to explore some of the apparent limitations of describing function technique for the analysis of nonlinear systems, and to show how the technique might be extended so as to overcome the indicated deficiencies. The problems were (a) the effects of stick and valve friction in fully powered, manual aircraft control systems, (b) limit cycles in satellite attitude control with off-on jets, and (c) the effects of aerodynamic hysteresis in the stability derivatives of tilt-wing VTOL aircraft. The results indicate that new describing functions can be developed as closed-loop functions provided that specific restrictions are met, that non-sinusoidal, Fourier series describing functions or a generalized periodic input describing function can be successful, but that they are extraordinarily difficult to apply, and that the aerodynamic nonlinearities which were considered are of small practical importance.

Report Availability

Full text available

Date Issued

1966-02

Provenance

Lockheed Martin Missiles & Fire Control

Type

report

Format

1 online resource