Accession Number:

AD0894547

Title:

Category II Performance and Flying Qualities Tests of the HH-53C helicopter

Descriptive Note:

Final rept. 26 Aug 1969-27 Feb 1970

Corporate Author:

AIR FORCE TEST CENTER EDWARDS AFB CA

Report Date:

1970-04-01

Pagination or Media Count:

28.0

Abstract:

HH-53C Category II evaluation to obtain data for the Flight Manual. The Flight Manual power required to hover was 2 to 7 higher than test data. Flight Manual specific range data were accurate at recommended cruise, but were up to 10 higher than test data at the higher airspeeds. Rotor blade compressibility effects resulted in up to a 5 increase in power required. Rotor blade compressibility was most significant during level flight when advancing blade-tip Mach numbers as high as 0.95 were obtained. Power required increased as much as 38 as advancing blade-tip Mach number was varied from 0.76 to 0.94. During level flight below 38,000 pounds and 5,000 feet density altitude, maximum airspeed was limited by either the up collective pitch stop or by the advancing blade-tip Mach number, rather than the aircraft airspeed redline, engine power, or any enginetorque limitations. The HH-53C exhibited positive static stability for all flight conditions except for a neutral or slightly negative longitudinal stability at approximately 35 KCAS for level flight and partial power descent. With the automatic flight control system AFCS on, it was stable about all axes.

Subject Categories:

  • Helicopters

Distribution Statement:

APPROVED FOR PUBLIC RELEASE