Airworthiness and Flight Characteristics Evaluation Improved Main Rotor Blade Installed on a YAH-1R Helicopter

The United States Army Aviation Engineering Flight Activity conducted an airworthiness and flight characteristics evaluation of the Kaman Aerospace Corporation improved main rotor blade (K-747) installed on a YAH-1R helicopter. The Bell Helicopter Textron YAH-1R was tested from 25 February through 10 June 1977 at three sites in California: Edwards Air Force Base (2302-foot evaluation) , Bishop (4120-foot elevation), and Coyote Flats (9980-foot elevation). A total of 82.9 test flight hours were flown of which 44.7 hours were productive. Bell B-540 and Kaman K-747 rotor blades were evaluated for performance, limited stability and control characteristics, and miscellaneous engineering items. The results of the B-540 blade tests were used as a base line for comparison with the K-747 test results. The YAH-1R helicopter with K-747 blade installed exhibited performance improvements in hover, climb, and portions of the level flight envelope.