Loss of Tail Rotor Effectiveness Evaluation of the OH-58C Helicopter with Directional SAS (Stability Augmentation System)
Abstract
The U.S. Army Aviation Engineering Flight Activity conducted a loss of tail rotor effectiveness (LTE) evaluation of the JOH-58C. The JOH-58C configuration includes a directional stability augmentation system (SAS) manufactured by the SFENA Corporation, the larger-diameter tail rotor, and the improved engine fuel control. Handling qualities were evaluated at Edwards AFB, California (elevation 2302 feet). Twenty-eight flights were conducted for a total of 26.7 productive flight test hours. Primary emphasis of the evaluation was to evaluate the handling qualities of the JOH-58C in comparison to the standard OH-58C. The limited authority SAS (7% of full control travel) will not significantly reduce the conditions conducive to LTE. The overall handling qualities of the JOH-58were moderately improved compared to the standard OH-58C. The concept of a SAS which damps uncommanded yaw rates demonstrated potential for reducing conditions conducive to LTE. However, the limited authority SAS saturated at small yaw rates (deg/sec) and did not significantly reduce the characteristic high yaw rates and moderate yaw attitude excursions observed in the JOH-58C. The JOH-58C exhibited moderate pitch, roll, and yaw excursions at 15 to 25 KTAS in azimuths from 240 degrees clockwise to 280 degrees. This characteristic was a shortcoming , upgraded from a deficiency for the standard OH-58C. Five additional shortcomings, of which four were previously identified in the standard OH-58C, were noted.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1988
- Accession Number
- ADA206181
Entities
People
- Christopher P. Butler
- Frederick W. Stellar
- James D. Brown
- Michael K. Herbst
- Timothy Hathorn