Accession Number : AD0674213

Title :   FEASIBILITY STUDY OF A HYBRID VIBRATION ISOLATION SYSTEM

Descriptive Note : Final rept.

Corporate Author : BOLT BERANEK AND NEWMAN INC VAN NUYS CA

Personal Author(s) : Bies, David Alan

PDF Url : AD0674213

Report Date : Aug 1968

Pagination or Media Count : 53

Abstract : The fluctuating lift of a helicopter rotor gives rise to undesirable vibration over a broad frequency range which in some cases may extend to as low as 3 Hz. Vibration isolation over this frequency range is very difficult to achieve with either a purely passive or an active vibration isolation system. A passive system will work well at high frequencies, but it will always have a low-frequency resonance where excitation will be amplified rather than reduced. An active system may work well at low frequencies, but it will have trouble meeting the frequency response requirements at high frequencies. The investigation of the feasibility of combining an active and a passive system was conducted to gain the advantages of both. The report shows that an active system may be used to control the resonant response of a passive system while preserving the isolation achieved at high frequencies. Isolation over a broad frequency range may be obtained by this means with only a small amplification of response at low frequencies.

Descriptors :   *HELICOPTER ROTORS, *VIBRATION ISOLATORS, AIRFRAMES, FEASIBILITY STUDIES, FREQUENCY, LIFT, MODEL TESTS, SHOCK(MECHANICS), VIBRATION

Subject Categories : Helicopters
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE