Anhedral tip blades for tiltrotor aircraft
US8066219B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 2010 |
| Grant date | Nov 29, 2011 |
| Priority date | — |
| Expiry date | Oct 13, 2030 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB64C27/463
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A tiltrotor aircraft having a fixed wing and tilting rotors has a rotor blade with a shaped tip portion that provides improved hover performance. The shaped tip portion preferably has a terminal anhedral of at least 20° with respect to its stacking line, and the blade has an overall twist from root to tip of at least 20°, and a thickness ratio between 19% and 30% at a radial station of 10%. These features advantageously conspire to provide a hover figure of merit of at least 0.84 and a cruise propulsive efficiency of at least 0.85. A controller preferably limits the rotor speed in sustained airplane-mode forward flight cruise of at most 40% of a hover maximum rotor speed, and alternatively or additionally limits a rotor edgewise advance ratio to at most 0.20.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.