Accession Number : AD0902068

Title :   Determination of the (Ideal Practical) Hover Efficiency of Circulation Control Rotors

Descriptive Note : Technical note

Corporate Author : DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD AVIATION AND SURFACE EFFECTS DEPT

Personal Author(s) : Williams, Robert M ; Hemmerly, Rodney A

PDF Url : AD0902068

Report Date : Aug 1971

Pagination or Media Count : 54

Abstract : An approximate analysis of the maximum hover performance of a Circulation Control Rotor is presented. Closed form equations are developed which conveniently show the contribution of the induced, profile, compressor and coriolis powers in terms of the basic airfoil equivalent lift to drag ratios. A range of rotor taper ratios and solidities are examined under the constraint of ideal twist distribution. A comparison is made with a conventional rotor using a NACA 0012 reference airfoil. It is demonstrated that the circulation control rotor can achieve comparable overall hover efficiencies (Figure or Merit) at significantly higher values of rotor thrust coefficient to solidity ratio than conventional rotors. The implications of these characteristics for helicopter design is then discussed briefly.

Descriptors :   *HELICOPTER ROTORS, *JET FLAPS, *ROTOR BLADES(ROTARY WINGS), AERODYNAMIC CHARACTERISTICS, AERODYNAMIC SLOTS, ANGLE OF ATTACK, BOUNDARY LAYER CONTROL, CAMBER, CORIOLIS EFFECT, DRAG, DUCTS, EFFICIENCY, EQUATIONS OF MOTION, GAS FLOW, HOVERING, LIFT, MATHEMATICAL MODELS, TWIST(AERODYNAMICS), VELOCITY, VORTICES

Subject Categories : Helicopters
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE