Experimental Investigation and Fundamental Understanding of A Slowed UH-60A Rotor at High Advance Ratios

This paper describes and analyzes the measurements from a full-scale, slowed RPM, UH-60A rotor tested at the National Full-Scale Aerodynamics Complex 40- by 80- ft wind tunnel up to an advance ratio of 1.0. A comprehensive set of measurements, that includes performance, blade loads, hub loads and pressures/airloads makes this data set unique. The measurements reveal new and rich aeromechanical phenomena that are special to this exotic regime. These include reverse chord dynamic stall, retreating side impulse in pitch-link load, large inboard-outboard elastic twist differential, supersonic flow at low subsonic advancing tip Mach numbers, diminishing rotor forces yet dramatic build up of blade loads, and dramatic blade loads yet benign levels of vibratory hub loads. The objective of this research is the fundamental understanding of these unique aeromechanical phenomena. The intent is to provide useful knowledge for the design of high speed, high efficiency, slowed RPM rotors of the future and a challenging database for advanced analyses validation.

[1]  William G. Bousman,et al.  Flight Testing the UH-60A Airloads Aircraft , 1994 .

[2]  Fred W. Piasecki,et al.  Challenges of flight control in a compound helicopter , 2010 .

[3]  Hyeonsoo Yeo,et al.  Optimum Design of a Compound Helicopter , 2009 .

[4]  Matthew W. Floros,et al.  Performance Analysis of the Slowed-Rotor Compound Helicopter Configuration , 2009 .

[5]  Hyeonsoo Yeo,et al.  Aeromechanics Analysis of a Heavy Lift Slowed-Rotor Compound Helicopter , 2007 .

[6]  Christopher A. Snyder,et al.  Summary of the Large Civil Tiltrotor (LCTR2) Engine Gearbox Study , 2010 .

[7]  Franklin D. Harris,et al.  Rotor Performance at High Advance Ratio: Theory versus Test , 2008 .

[8]  Marvin D. Marks.  Flight Test Development of XV-1 Convertiplane , 1957 .

[9]  D. Gibbings.  The Fairey Rotodyne: technology before its time? , 2004 .

[10]  J. C. Biggers,et al.  An investigation of full-scale helicopter rotors at high advance ratios and advancing tip Mach numbers , 1968 .

[11]  Raymond L Robb.  Hybrid helicopters : compounding the quest for speed , 2006 .

[12]  Charles F. Niebanck.  A Comparison Of Dynamically Scaled Model Rotor Test Data With Discrete Azimuth Aeroelastic Stability Theory , 1969 .

[13]  Kenneth M. Rosen.  A Prospective: The Importance of Propulsion Technology to the Development of Helicopter Systems with a Vision for the Future The 27th Alexander A. Nikolsky Lecture , 2008 .

[14]  Inderjit Chopra,et al.  Wind Tunnel Testing for Performance and Vibratory Loads of a Variable-Speed Mach-Scale Rotor , 2011 .

[15]  John B Wheatley,et al.  Full-Scale Wind-Tunnel Tests of a PCA-2 Autogiro Rotor , 1935 .

[16]  Gloria K. Yamauchi,et al.  NASA Heavy Lift Rotorcraft Systems Investigation , 2013 .

[17]  Danny A. Barrows,et al.  Blade Deflection Measurements of a Full-Scale UH-60A Rotor System , 2010 .

[18]  Robert F. Handschuh,et al.  Concepts for Variable/Multi-Speed Rotorcraft Drive System , 2008 .

[19]  Bruce D. Charles,et al.  WIND TUNNEL INVESTIGATION OF SEMIRIGID FULL-SCALE ROTORS OPERATING AT HIGH ADVANCE RATIOS , 1969 .

[20]  Matthew W. Floros,et al.  Stability and Control Analysis of the Slowed-Rotor Compound Helicopter Configuration , 2007 .

[21]  W. E. Spreuer.  Experimental Flight Tests of the XH-51A Compound Helicopter , 1968 .

[22]  Thomas R. Norman,et al.  Full-Scale Wind Tunnel Test of the UH-60A Airloads Rotor , 2011 .

[23]  David,et al.  Development Testing of the Sikorsky X2 Technology Demonstrator , 2009 .