PRELIMINARY INVESTIGATION OF TROLLEY LOW ALTITUDE AIRDROP CONCEPT

The Lockheed Trolley Low Altitude Airdrop Concept employs a towed parachute to maintain tension in a long cable from which a load may be suspended until it contacts the ground. After it is extracted by the force of the parachute, the load slides beneath the cable until it contacts the ground. Rate of descent is controlled by a winch in the aircraft that reels in the cable as needed to minimize impact velocity. This preliminary concept-oriented investigation was undertaken to determine the feasibility of developing this system for operational use. The study consists of analytical evaluation of the operational parameters, limited component testing, and consideration of basic hardware requirements. Digital and analog computer simulations of Trolley airdrop are among the analytical methods employed. Two tests of a parachute towed on a Trolley cable behind a C-130 aircraft are evaluated. Laboratory tests of certain components are analyzed with respect to flight safety. Results of the study indicate no problems which preclude the development of the Trolley airdrop concept into an operational system for airdropping individual loads of 2,000 to 10,000 pounds from a C-130 below 500 feet. Comparison of Trolley to conventional airdrop shows: (1) costs are reduced, (2) accuracy is improved, (3) impact velocities are lower, (4) rigging is simplified. However, the system is unsuitable for mass assault where several unit loads must be dropped per aircraft pass.