Ramesh T Patel

US Patent:

55271553, Jun 18, 1996

Filed:

Nov 1, 1993

Appl. No.:

8/146831

Inventors:

Steve P. Chen - Chandler AZ
John E. Schibler - Fountain Hills AZ
Ramesh J. Patel - Mesa AZ

Assignee:

McDonnell Douglas Corp. - Long Beach CA

International Classification:

F01D 514

US Classification:

41622600

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.

US Patent:

56913915, Nov 25, 1997

Filed:

Dec 5, 1994

Appl. No.:

8/349378

Inventors:

Steve P. Chen - Chandler AZ
John E. Schibler - Fountain Hills AZ
Ramesh J. Patel - Mesa AZ

Assignee:

McDonnell Douglas Helicopter - Meza AZ

International Classification:

C08J 508

US Classification:

521 99

Abstract:

A variable pitch fan for a helicopter equipped with a NOTAR. RTM. 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.