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:
Dec. 24, 2002
Filed:
Nov. 08, 2001
Daniel A. Wachspress, Lawrenceville, NJ (US);
Todd R. Quackenbush, Pennington, NJ (US);
Continuum Dynamics, Inc., Ewing, NJ (US);
Abstract
A rotor blade has a local geometric twist angle &thgr;=ƒ(r/R), with R being the blade span and r being the distance along the blade span from the axis of rotation. The blade has an inner region between an (r/R) =0.20±0.04 and a transition point at (r/R) =0.75±0.04, wherein &thgr; at (r/R) has a positive value and is greater than or equal to &thgr; at (r/R) . A blade tip region includes a first portion between (r/R) and (r/R) >(r/R) , wherein &thgr; continuously decreases from &thgr; to &thgr; at (r/R) , and &Dgr;&thgr; =|&thgr; −&thgr; |>3°, and a second portion between (r/R) and the blade tip, wherein &thgr; continuously increases from &thgr; to &thgr; at the tip, and &Dgr;&thgr; =|&thgr; −&thgr; | is at least about 3° and no greater than about 20°. This geometry pushes the vortex trailed by the blade tip away from the blade and thus increases blade performance. In a preferred tiltrotor blade embodiment, &Dgr;&thgr; =|&thgr; −&thgr; |=32.5°±7.5°, &thgr; continuously decreases from (r/R) to (r/R) , (r/R) =0.91±0.04, &Dgr;&thgr; =7.5°±2.5°, and &Dgr;&thgr; =10°±6°. In a preferred helicopter blade embodiment, &Dgr;&thgr; =|&thgr; −&thgr; |=20°±5°, &thgr; continuously decreases from (r/R) to (r/R) , (r/R) =0.94±0.04, &Dgr;&thgr; =5°±2°, and &Dgr;&thgr; is from about 3° to about 10°. Another embodiment of the invention uses adjustable flaps to control &thgr;=ƒ(r/R) in an inboard region of a helicopter blade to optimize performance in hover and forward flight regimes.