Army Preliminary Evaluation YAH-1R Improved Cobra Agility and Maneuverability Helicopter. Addendum
ARMY AVIATION ENGINEERING FLIGHT ACTIVITY EDWARDS AFB CA
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Follow-on testing of the YAH-1R helicopter was conducted subsequent to the Army Preliminary Evaluation APE of that aircraft. In the six test flights, emphasis was placed on evaluating maneuvering stability in high-speed diving flight and on investigation of enginerotor system static and dynamic droop characteristics. This report is intended to amplify and expand the APE report and is not a rewrite of that report. In a dive at 155 KIAS, the YAH-1R was found to have stable maneuvering stability at normal load factors below 1.4 and neutral maneuvering stability at load factors above 1.4. The enginerotor system static and dynamic droop characteristics were unaltered from those described in the APE report. In response to requests, the Army Aviation Systems Command acted to increase the engine output shaft speed limit to 6900 rpm for 10 seconds independent of power. This new proposed engine limit greatly reduces the pilot workload during rapid deceleration maneuvers however, the engine rotor speed increase was unaltered and thus remains a shortcoming. No additional deficiencies or shortcomings were determined during this evaluation the conclusions of the APE report were unaltered.
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