“Load Snubbing” A Solution to the Problem of Terrain Flying With External Cargo

In order to survive the hostile enemy air defense threat existing on mid-intensity battlefields of the future, the CH-47 helicopter will engage in terrain flying while performing external cargo resupply missions. A comprehensive flight simulation analysis was conducted recently for the Army, to define Chinook capabilities and limitations related to terrain flight with external payloads. Load "snubbing" was identified as the best approach for minimizing unfavorable load motion, stability, and masking problems typical of conventional sling suspension schemes. Preliminary design development of the snubbing concept produced an External Cargo Handling System (ECHS), capable of transporting 8×8×20 foot MILVAN or Gondola containers. The ECHS consists of an electrically powered self-hoisting interface adapter framework, which rigidly snubs the MILVAN against the aircraft landing gear to prevent motion and provide vibration isolation. Wind tunnel testing of the concept revealed that load snubbing provides either a neutral or positive stability contribution, and because of reduced download and drag, a performance benefit when compared to suspensions in use today.