Accession Number : ADP005984

Title :   Controlling the Dynamic Environment during NOE Flight,

Corporate Author : BELL HELICOPTER TEXTRON INC FORT WORTH TX

Personal Author(s) : Halwes, Dennis R.

Report Date : JUN 1987

Pagination or Media Count : 9

Abstract : A six degree-of-freedom (DOF) isolation system using six LIVE units has been installed under an Army/NASA contract on a Bell 206LM helicopter. This system has been named the Total Rotor Isolation System, or TRIS. To determine the effectiveness of TRIS in reducing helicopter vibrations, a flight verification study was conducted at Bell's Flight Research Center in Arlington, Texas. The objective was to demonstrate a 90% (or greater) isolation of the helicopter fuselage from the main rotor forces and moments transmitted at the blade passage frequency, which is 4/rev in the case of the Bell 206LM. The flight test was the final phase of a program performed by Bell under a NASA Langley Research Center contract with funding by the U.S. Army Aerostructures Directorate. The flight test data from the testbed aircraft indicate that the program objectives have been surpassed; the 4/rev vibration envelope, which traditionally has high vibration levels. Results of flight tests to date indicate over 95% suppression of vibration levels from the rotor hub to the pilot's seat at a considerable weight savings over traditional antiresonant isolation concepts. In addition, the TRIS installation was designed with a decoupled control system has has shown a significant improvement in aircraft flying qualities. The improvement was such that it permitted the trimmed aircraft to be flown 'hands-off' for a significant period of time, over 90 seconds. NATO.

Descriptors :   *HELICOPTER ROTORS, AIRCRAFT, CONTRACTS, CUTTING, DYNAMICS, FLIGHT ENVELOPE, ENVIRONMENTS, EXPERIMENTAL DATA, FLIGHT, FLIGHT TESTING, FUSELAGES, HELICOPTERS, HUBS, INTENSITY, ISOLATION, MOMENTS, NATO, PILOTS, QUALITATIVE ANALYSIS, RESEARCH FACILITIES, ROTOR BLADES(ROTARY WINGS), SEATS, TEST BEDS, TEXAS, TIME, VIBRATION, WEIGHT REDUCTION.

Subject Categories : Helicopters

Distribution Statement : APPROVED FOR PUBLIC RELEASE