Design, Development, and Flight Demonstration of the Loads and Stability Characteristics of a Bearingless Main Rotor.
Abstract
The successful design, development, bench and whirl testing, and flight demonstration of the loads and stability characteristics of a bearingless main rotor (BMR) on the BO-105 helicopter were accomplished. The initial tests indicated that ground resonance damping was inadequate. For this program, a minimal modification, the stiffening of the aircraft skid landing gear, provided adequate damping for the continuation of the program. The BMR/BO-105 had similar air resonance to the baseline BO-105, except at low collective pitch settings where the BMR had lower but sufficient damping. Vibration levels were generally similar to the baseline, but in some regimes were higher. Maneuvering stability showed a significant improvement and other flight characteristics were similar to those of the standard BO-105. The level flight speed was limited only by power available and the 35-hr flight test program was not limited by structural characteristics. The feasibility of helicopter bearingless main rotors has thus been demonstrated. Understanding of the loads distribution in the two-beam lag/flap/torsion flexure at the blade root of this configuration needs improvement. Use of Froude scaled model wind tunnel testing accurately predicted the flight aeromechanical stability characteristics of the BMR; however, the analytical stability prediction methodology, although sufficiently accurate in hover, requires improvement and expansion into the forward flight modes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1980
- Accession Number
- ADA086754
Entities
People
- Peter G. C. Dixon
Organizations
- Boeing Rotorcraft Systems