Rotary Wing Vehicle External Stores Jettison Envelope Pilot Established Requirements.
Final rept. Mar 68-Feb 70,
ARMY AVIATION SYSTEMS TEST ACTIVITY EDWARDS AFB CALIF
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The numbers and types of Army helicopters having external stores configurations have increased significantly in recent years. Extensive testing has been required to establish or demonstrate the jettison envelope. In some cases, this envelope has not always been compatible with the mission requirements since there is no firm guidance concerning the aircraftstores interface or requirements for the stores jettison capability or characteristics. The jettison envelope study program was designed to examine the envelope requirements from a pilots viewpoint and develop a technical basis for establishing design, demonstration and testing requirements. Either aerodynamic or forced separation may be used to satisfy the requirements. It was determined that the aircrafts stability and control characteristics can be used to define the minimum jettison envelope that can be perceived by the pilot. Of these characteristics, lateral side-force is the most reliable cue available to the pilot. This is a function of the static directional stability and effective dihedral. A lateral sideforce corresponding to an acceleration of 0.1g was recognized by all pilots participating in the program. A method is shown whereby this information can be used to develop a recognizable envelope from which the pilot should be able to safely jettison stores. This method can be used as a technical basis to provide design guidance, establish demonstration requirements and develop more effective testing procedures. Author