The design of an autonomous autorotative payload delivery system, called the Autobody, is addressed. The Autobody must be capable of passively deploying a payload, consisting of an electronics package, on ground from a conventional aircraft, by means of an autorotative fixed-pitch rotor. Operational requirements specify the total vehicle mass as 5 lbs, and require the vehicle to have a four foot diameter, four bladed rotor. It is important that the system decelerates during the transient state of the flight, prior to the steady state of autorotation, to minimize its impact upon landing and to ensure that the payload and the vehicle reach the ground safely. A novel rotor hub design incorporating negative pitch-flap coupling and a negative precone is proposed to passively achieve the transition to a state of steady autorotation. An analytical model is developed to predict the Autobody behavior in transient and steady states of autorotation. Wind tunnel tests are performed on a scale model to investigate the effect of the design variables on the steady state performance of the system. After establishing proof-of-concept in the wind tunnel, a full scale instrumented prototype was dropped from a hot air balloon. The goal of these instrumented flight tests was to obtain data to validate the analysis, which can then be used to design an optimum rotor with minimum descent rate.
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