Accession Number : AD0776984

Title :   Helicopter and V/STOL Noise Generation and Suppression.

Descriptive Note : Final rept. Nov-Dec 68.

Corporate Author : NATIONAL ACADEMY OF ENGINEERING WASHINGTON D C AERONAUTICS AND SPACE ENGINEERING BOARD

Report Date : NOV 1968

Pagination or Media Count : 19

Abstract : Recent discussions between scientists of the United States Army Research Office, Durham, North Carolina, and members and staff of the National Academy of Sciences and National Academy of Engineering have identified an urgent need for renewed effort toward suppression of helicopter and V/STOL noise in military operations. Use of the term VTOL is intended to apply to all aircraft capable of vertical flight, of which the helicopter is the best known example. Major recommendations were: (1) Criteria should be established for determining the benefits and costs of noise reduction, on a quantitative basis in both military and commercial operations. (2) Factors determining aural detectability should be established for acoustic signatures of type generated by VTOL aircraft. Annoyance factors should also be established. (3) Mechanisms of noise generation by rotors and propellers should be established by a basic research program including analytical studies and experimental investigations. (4) Standards should be established for measurement of noise levels and data reduction which could be applied on a consistent basis by all investigators using commercially available equipment.

Descriptors :   *Helicopters, *Short takeoff aircraft, *Aircraft noise, Noise(Sound), Noise reduction, Aerodynamic noise, Jet engine noise, Rotor blades(Rotary wings), Research management

Subject Categories : Helicopters
      V/STOL
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE