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Under the Joint Precision Airdrop System program, a Draper Laboratory autonomous Guidance, Navigation, and Control (GN&C) software package that enables precision payload airdrop delivery using large parafoils has been developed in prototype form and successfully flight tested. The modular software design is structured to accommodate parafoil airdrop systems for payloads ranging from under 2,000 lb to over 30,000 lb. The initial GN&C software implementation has been demonstrated on the Para-Flite Dragonfly 10,000 lb-class parafoil using an Airborne Guidance Unit (AGU) provided by Wamore, Inc. and an avionics package provided by RoboTek. Among the primary avionics selection criteria was low component cost, resulting in use of a processor with very limited data throughput capability. To accommodate the processor limits, the Guidance algorithm includes table driven trajectory data that guides the parafoil through precision final-descent maneuvers while imposing very limited processor throughput burden. The GN&C algorithms and associated mission planning software have also been incorporated into the Precision Airdrop System laptop personal computer. This accommodates easy, in the field, ground loading of the GN&C software onto the AGU and enables PADS updates of the airdrop system mission files during flight of the carrier aircraft to the airdrop release point. The details of the GN&C design and flight test results to date are discussed.

A 3,500 ft 2 , 10,000 lb capacity, low cost cargo Ram-air is being designed and developed by Para-Flite, Inc. for the U.S. Army Natick Soldier Center (Natick) under the JPADS ACTD program. The airdrop system has been designed for deployment from 25Kft MSL at speeds of 150 KIAS. Test drops have been conducted with the system in order to finalize the deployment process and generate trajectory data suitable for the development of an autonomous guidance algorithm, of which C.S. Draper Laboratory is the designing authority. This paper presents the design philosophy and outlines the aerodynamic, structural and manufacturing considerations. Being driven by cost reduction, the design focused on using conventional materials and manufacturing techniques while trying to maximize gliding performance. The main canopy uses a cutterless slider reefing method which eliminates a dependency for complicated staged openings. Drop tests indicated that the parafoil was extremely stable in flight and generated a maximum glide ratio of 4:1. This level of glide efficiency matches or exceeds prior performance characteristics for similarly sized systems. Guided tests showed that the parafoil is also reasonably responsive for it size, with maximum steady state turn rates exceeding 9.0 deg/s. Nomenclature

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