Aerodynamic performance of a 0.27-scale model of an AH-64 helicopter with baseline and alternate rotor blade sets
National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1990 - Transportation - 21 pages
Performance of a 0.27-scale rotor model designed for the AH-64 Apache helicopter (alternate rotor) was measured in hover and forward flight compared with an AH-64 baseline rotor model. Thrust, rotor tip Mach number, advance ratio, and ground proximity were varied. In hover, at a nominal thrust coefficient of 0.0064, the alternate rotor used about 6.4% less power than the baseline rotor. The corresponding thrust increase at this representative hover power condition was approximately 4.5%, which represents an equivalent full-scale increase in lift capability of about 660 lb. Comparable results were noted in forward flight, except for the high-thrust, high-speed cases investigated (Advance ratio = 0.30), where the baseline rotor was slightly superior. Reduced performance at the higher thrusts and speeds was probably caused by Reynolds number effects and blade elasticity differences. Keywords: Rotor blades rotary wings; Blade tips; Attack helicopters; Helicopter rotor performance; Model rotor testing; Tapered rotor blades; Ground effects. (edc).
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22-Foot Subsonic Tunnel A/tjp advance ratio aerodynamic Aerostructures Directorate AH-64 Apache AH-64 model airfoil alternate blades alternate rotor angle of attack baseline and alternate baseline blades baseline rotor Baseline vs alternate blade elastic calculated design goal Ci/aj coefficient for baseline Cq/at Cq/ot Ct Hover Figure 17 figure of merit flight data forward flight forward speeds ft2 f full scale fuselage download GRMS ground effect Helicopters Rotor Hover 64 Baseline hover at Mtip hover performance hover testing improvement O Baseline knots Langley 14 Langley Research Center lift coefficient model rotor Mtjp planform rotor design rotor drag coefficient rotor hub Rotor lift variations rotor model rotor performance rotor systems rotor thrust coefficient rotor torque coefficient rotors in hover SLS atmospheric conditions tail boom terms of rotor test-section tip Mach number tip region tip Reynolds number torque coefficient versus U.S. Army Vehicle torque coefficient versus rotor thrust versus thrust coefficient