NOISE SURVEY HU-1A HELICOPTER WITH MODIFIED EXHAUST SYSTEM
Abstract
Noise levels of Army HU-1A helicopters 9-1632 (equipped with a modified exhaust system) and 58-2080 (standard configuration) were recorded under similar operating and ambient conditions. Some difference exists in the 200 ft directivity patterns of the aircraft in hover, along with an increase in high frequency noise in take-off and landing. The latter may be due to pilot techniques in achieving the requirements of Test 2. Except for these, however, sound pressure levels of the aircraft, under similar operating conditions, are considered the same. Other differences lie within the envelope of repeatability. It is concluded that the modified exhaust system of HU-1A No. 9- 1632 does not significantly affect the acoustic characteristics of the aircraft.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1961
- Accession Number
- AD0267575
Entities
People
- H. Sternfeld Jr.
- R. H. Spencer
Organizations
- Boeing Rotorcraft Systems