This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Helicopters and Propeller-Type VTOL Aircraft in the Light of Technologies
Annotation ability available
Sector:
Language:
English
Abstract
Pure and compound helicopters (including those with stoppable or stowable rotors) as well as propeller-type VTOLs are examined regarding their possibilities and limitations resulting from aerodynamics and structures. Trends in effective lift-to-drag ratio with flying speed and agility are discussed, along with other performance items. Aeroelastic, dynamic and structural aspects of rotary wing aircraft are considered and specific limitations due to those phenomena indicated. An interplay between design concepts and gross and empty weights is illustrated by the example of operations reflecting a combat type mission. The totality of these considerations indicates that a 200-knot pure helicopter is feasible with the possibility of not exceeding cyclic stress and vibration levels of contemporary 150-knot helicopters. However, the effective lift-to-drag ratio at speeds of about 200 knots would be quite low. Compounding improves lift-to-effective drag ratio at such speeds slightly and moves the various aeroelastic barriers, up to speeds of 250 knots. However, this leads to higher gross and empty weights. Simple stopping of rotors brings little improvement in the speed and range capabilities at the expense of still higher weights. Folding is more promising as far as the performance is concerned, and gross and empty weight penalties are no higher than in stopping. Retraction of the rotor improves aerodynamic cleanness to the levels of propeller type VTOL (tilt wing) aircraft, but weight penalties are the highest. Because of its superior performance, high level of agility and absence of fundamental aeroelastic limitations, the tilt wing type is seen to be outstanding for the combat type missions considered.
Authors
Topic
Citation
Stepniewski, W. and Young, M., "Helicopters and Propeller-Type VTOL Aircraft in the Light of Technologies," SAE Technical Paper 650193, 1965, https://doi.org/10.4271/650193.Also In
References
- Tarczynski T. “Development of Retractable Rotor.” Journal of the American Helicopter Society 2 Apr. 1957
- Mallen J. “Comparative Study of Various Types of VTOL Transport Aircraft.” Final Summary Report, R-85, Vertol's Study under Army Contract, through ONR July 1956
- Legrand F. “Structural Behavior of the Super Frelon in High Speed Flight.” Proceedings of the 20th Annual National Forum of AHS 109 118 Washington, D.C. May 1964
- Wachs M. Rabbott J. Jr. “Rotary Wing Aircraft Design Trends.” Nov. 1963
- Miller R. H. “On the Computation of Airloads Acting on Rotor Blades in Forward Flight.” JAHS 7 2 April 1962
- Davenport F. J. “A Method for Computation of the Induced Velocity Field of a Rotor in Forward Flight, Suitable for Application to Tandem Rotor Configuration.” Journal of the American Helicopter Society 9 3 July 1964
- Cresap W. L. VanWyckhouse J. F. “Flight Research with Winged and Auxiliary Propulsion Compound Helicopters.” Proceedings of the 20th Nat. Forum of American Helicopter Society May 13-15 1963
- Fry B. “Low Speed Aerodynamic Flight Boundaries and Control Aspects of Tilt-Wing Aircraft.” to be presented at the 21st National Forum of American Helicopter Society Washington, D.C. May 1965
- Young M. I. “The Helicopter of the Future: A Challenge to the Aeroelastician.” Symposium on Aeroelastic and Acoustic Problems of V/STOL Aircraft, The Institute of Vibration and Sound University of Southampton Southampton, England September 1965
- Boeing Co., Vertol Division & DynaStructures, Inc., Report No. 64-K-002 “On the Static and Dynamic Behavior of Anisotropic Viscoelastic Rotor Blade Structures.” March 1965
- Ham N. D. “An Experimental Investigation of Stall Flutter.” Journal of the American Helicopter Society Jan. 1962
- Young M. I. “A Theory of Rotor Blade Motion Stability in Powered Flight.” Journal of the American Helicopter Society 9 3 July 1964
- Stepniewski W. Z. Schneider J. J. “Design Philosophy and Operational Requirements of Subsonic VTOL Aircraft.” Journal of Aircraft 1 3 May-June 1964
- Hafner R. “Domain of Convertible Rotor.” Journal of Aircraft 1 6 Nov-Dec. 1964
- Young A. M. “Variable Diameter Propeller.” U.S. Patent 3,128,829 Apr. 14 1964