Flight Test Development of a Helicopter-Towed Surface Delivery System.
NAVAL AIR TEST CENTER PATUXENT RIVER MD
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The requirement for the U.S. Coast Guard to rapidly deploy antipollution equipment to offshore or remote sites generated a proposal to utilize an HH-3F helicopter to tow a planing hull Fast Surface Delivery FSD sled. The proposal was unique in that the mass of the towed surface vessel equalled or exceeded the mass of towing helicopter. The U.S. Naval Air Test Center undertook the design and fabrication of prototype hardware and the development of towing techniques and a recommended flight envelope. The design was driven by a requirement for the towing equipment to be two man transportable, manually operable, and easily removable. Two significant features of the resulting design were the use of a Kevlar 49 towing cable and the development of a quick-release hook capable of repeated releases at rated load. Flight testing revealed two families of power required curves as functions of the FSD sled operation as a displacement or planing hull. There was also a measurable sensitivity to the center of gravity location of the FSD sled. FSD sled reactions to sea states caused divergent oscillations in tow tension which could be easily damped by pilot technique. The development and test program demonstrated the suitability of helicopters to perform as a high-speed towing vehicle for very rapid overwater delivery of payloads not otherwise air transportable or rapidly surface deliverable. Author
- Machinery and Tools