Full-Scale S-76 Rotor Research In The 80- By 120-Foot Wind Tunnel

The objectives of this wind tunnel test were to evaluate the capability of the 80x120 test section as a hover facility; acquire forward flight rotor performance data for comparison with analytical results; and acquire S-76 forward flight rotor performance data in the 80x120 wind tunnel to compare with existing and future 40x80 data for evaluation of differences and similarities between the two full-scale wind tunnel facilities.

The UH-60A Airloads Program's, jointly sponsored by NASA and the U.S. Army, objective was to obtain comprehensive, accurate, documented airloads data over the complete operating limits of the UH-60 rotor system that will have long-term value and timely, widespread accessibility so that the rotorcraft community can increase their understanding of rotor behavior, refine and validate their analysis tools, and design improved rotorcraft.

Wind tunnel test measurements, flight test measurements, and analytical prediction play a key role in the development of new rotor systems. Tests are typically performed using a range of rotor system sizes and wind tunnel test facilities. To assure the accuracy of wind tunnel testing methodology, a validation study is in progress using test results from model- and full-scale tests in comparison with flight test data.

The primary objective of the wind tunnel test was to evaluate the Sikorsky Bearingless Main Rotor in the following five areas: dynamics and stability, rotor structures and loads, handling qualities, aeroperformance and acoustics. A secondary objective of this test was to evaluate the effects of active controls on rotor loads, performance and acoustics.

The objectives of this test were to experimentally simulate the aerodynamics and acoustics of parallel (2-D), unsteady helicopter rotor blade-vortex interactions, in a manner closely matching the simplified computational models frequently used for numerical simulations.

Two tests of an individual blade control (IBC) system for a full-scale helicopter rotor were performed; the first in 1993 and the second in 1994. The objective of the investigations were to evaluate the potential of individual blade control to improve rotor performance, to reduce blade vortex interaction (BVI) noise, and to alleviate helicopter vibrations.

The tilt rotor aircraft holds great promise for improving air travel in the future. It's benefits include vertical take off and landing combined with airspeeds comparable to propeller driven aircraft. However, the noise from a tilt rotor during approach to a landing is potentially a significant barrier to widespread acceptance of these aircraft. The XV-15 Aeroacoustic test will measure the noise from a tilt rotor during descent conditions and demonstrate several possible techniques to reduce the noise.

A key part of NASA's aeronautics research is reducing noise to make helicopters and tiltrotors more acceptable to the public. The objective of the In-Flight Rotorcraft Acoustics Program (IRAP) is to acquire rotorcraft noise data in flight for comparison to wind tunnel data. The type of noise of concern is "blade-vortex-interaction," or BVI, noise.

In an effort to obtain better predictive capabilities and to better understand bearingless rotor dynamics and loading, McDonnell Douglas Helicopter Systems (MDHS) and NASA Ames jointly conducted a wind tunnel test program to study the MDHS advanced bearingless rotor concept.

NASA Ames Research Center and Westland Helicopters Limited (WHL) established a joint research program to document the flight tests of a hingeless Lynx helicopter and perform a correlation study with these data. The flight tests were conducted by WHL in 1985 to evaluate the performance and load characteristics of the Lynx-XZ170 helicopter equipped with rectangular metal blades.

Coupled wing/rotor whirl-mode aeroelastic instability is the major barrier to increasing tiltrotor speeds. This research investigated the unusually simple approach of adjusting the chordwise positions of the rotor blade aerodynamic center and center of gravity to improve the stability boundary of the full aircraft.

The Full-Span Tilt Rotor Aeroacoustic Model is a quarter scale V-22 Osprey being tested in the 40-by 80- Foot Wind Tunnel at Ames Research Center, Moffett Field CA.

Beginning October 2, 2000 the Rotorcraft Aeromechanics Branch will begin testing of Millennium Jet Inc.'s SoloTrek XFV ducted rotor in the 7- by 10-Foot Wind Tunnel at Ames Research Center, Moffett Field CA.

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URL: http://rotorcraft.arc.nasa.gov/
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Last Modified: Thursday, 27-Dec-2007 14:38:49 PST