This paper describes the analysis, fabrication and hover testing of a rotor with extremely flexible carbon-fiber composite rotor blades. The flexibility of the rotor blades is such that they can be rolled into a compact volume and stowed in the rotor hub. While the benefits of a variable-diameter, stowable rotor for full-scale, high-speed helicopters is well known, the present study focuses on application to a micro-helicopter. An 18 inch diameter rotor having untwisted, constant chord blades with a circular arc airfoil profile, is discussed. A comprehensive rotor aeromechanics code is used to analyze the behavior of the flexible rotor blades and to investigate the effect of a tip mass on the rotor stability. The hover performance of a two-bladed rotor with flexible blades is compared to that of a rotor with rigid blades having an identical planform and airfoil section. Stable operation of the flexible rotor in hover was achieved by positioning the tip mass at a suitable chordwise location. A maximum Figure of Merit of 44% was measured for the rigid rotor blades and 22% was measured for the flexible rotor blades. In general, the high twist induced in the flexible rotor blades resulted in a lower thrust and decreased efficiency compared to the rigid rotor blades. Future plans for increasing the efficiency for the flexible rotor blades and expanding the test envelope into forward flight are described.
Investigation of an extremely flexible stowable rotor
Untersuchung eines extrem flexiblen, verstaubaren Rotors
AHS International, Annual Forum, 65 ; 113-124
2009
12 Seiten, 16 Bilder, 3 Tabellen, 23 Quellen
Conference paper
English
Investigation of an Extremely Flexible Stowable Rotor
British Library Conference Proceedings | 2009
|