The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 27, 1987
Filed:
Jun. 06, 1986
Wolfgang Hassenpflug, Freiburg, DE;
Rainer Schwable, Garbsen, DE;
Litef GmbH, Freiburg im Breisgau, DE;
Abstract
A method is disclosed for determining the horizontal airspeed of helicopters in low speed ranges. At least three control functions, .theta..sub.o,i (collective pitch), .theta..sub.s,i (longitudinal control) and .theta..sub.c,i (lateral control) are measured. The magnitude of the horizontal airspeed, V.sub.H,i, is determined from its known relationship to .theta..sub.o,i. This magnitude is included in non-linear calibration equations .theta..sub.s (V.sub.H, .psi.) and .theta..sub.c (V.sub.H, .psi.) and control profiles .theta..sub.s (V.sub.H,i, .psi.) and .theta..sub.c (V.sub.H,i, .psi.) are derived therefrom. The measured values .theta..sub.s,i and .theta..sub.c,i are applied to the respective control profiles and corresponding phase pairs .psi..sub.s,1, .psi..sub.s,2 and .psi..sub.c,1, and .psi..sub.c,2 located. The pairs are compared and the incident flow angle .psi..sub.i is determined as the value common to the two pairs. From this information, the components of the horizontal airspeed are found from the relationships: