This thesis presents the design, testing and analysis of an autonomous autorotative payload delivery system called the Autobody. The Autobody must passively deploy a payload on ground from an aircraft by means of an autorotative rotor. The system must achieve the steady state autorotation quickly to minimize its impact upon landing. A hub design incorporating negative pitch-flap coupling, negative blade pitch and a negative precone is implemented to passively achieve the transition to a state of steady autorotation. An analytical model is developed to predict the Autobody behavior in steady state autorotation. Wind tunnel tests are performed to validate the theory. Good correlation with theory is observed. An optimum configuration is then designed based on the analysis. The instrumented prototype is flight tested by dropping it from a hot air balloon. Based on the theory and the flight tests, it is concluded that the proposed Autobody meets all operational requirements.