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The High Speed Challenge for Rotary Wing Aircraft
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English
Abstract
This paper reviews the problems associated with developing a vertical takeoff and landing (VTOL) aircraft that has desirable helicopter-like attributes in hover and low speed operation but is capable of efficient high subsonic cruise speed. A number of different configurations that have been proposed are reviewed and an assessment is made of the relative probabilities of future success. Factors considered to be important discriminators include speed potential, disk loading, empty weight fraction, the need for supplementary propulsion systems or convertible engines, and technical risk. The tilt-rotor configuration has considerable merit but will not achieve the highest speeds desired. It is concluded that incorporation of variable geometry, in the form of a variable diameter rotor system, has the best chance of providing the “ideal” VTOL. The variable diameter tilt-rotor adds on the order of 100 knots to the speed potential of the tilt-rotor and provides numerous other benefits as well. For highest speeds, the variable-diameter single stowed rotor configuration has the desired combination of attributes.
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Citation
Fradenburgh, E., "The High Speed Challenge for Rotary Wing Aircraft," SAE Technical Paper 911974, 1991, https://doi.org/10.4271/911974.Also In
References
- Fradenburgh E.A. Murrill R.J. Kiely E.F. “Dynamic Model Wind Tunnel Tests of a Variable-Diameter, Telescoping-Blade Rotor System (TRAC Rotor)” Sikorsky Aircraft, USAAMRDL Technical Report 73-32, Eustis Directorate U.S. Army Air Mobility R&D Laboratory Fort Eustis, VA July 1973
- Frint H.K. “Design Selection Tests for TRAC Retraction Mechanism” Sikorsky Aircraft, USAAMRDL Technical Report 76-43, Eustis Directorate January 1977
- Fradenburgh E.A. Hager L.N. Kefford N.F.K. “Evaluation of the TRAC Variable-Diameter Rotor: Preliminary Design of a Full-Scale Rotor and Parametric Mission Analysis Comparisons” USAAMRDL-TR-75-54 February 1976
- Fradenburgh E.A. “Improving Tilt Rotor Aircraft Performance with Variable-Diameter Rotors” Paper presented at the 14th European Rotorcraft Forum Milano, Italy 20-23 September 1988
- Scott M.W. “Summary of Technology Needs for High Speed Rotorcraft Study” Paper presented at the NASA/Industry Rotorcraft Meeting American Helicopter Society 47th Annual National Forum Phoenix, Arizona 8 May 1991