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:
Jun. 18, 1996
Filed:
Nov. 01, 1993
Steve P Chen, Chandler, AZ (US);
John E Schibler, Fountain Hills, AZ (US);
Ramesh J Patel, Mesa, AZ (US);
McDonnell Douglas Corp., Long Beach, CA (US);
Abstract
A variable pitch fan for a helicopter equipped with a NOTAR.TM. mechanical antitorque directional control system comprises a plurality of blade assemblies. Each blade assembly includes a blade portion, which is molded from a blended material which includes fiber reinforced polypropylene. A key to the invention is the use of long fibers, having a length of at least approximately one-half inch, for reinforcement, the long fibers providing for about twice the pull-out strength of short or chopped fibers. Another key aspect of the invention is the use of a blowing agent in the blended material, which serves to reduce weight and warpage by creating a foamed structure having a variable density, the structure retaining considerable strength because of the fiber reinforcement. The blade portion is molded about a spar which has holes therethrough, the holes providing a mechanical interlock between the blade and the spar.