Dynamics of a Small Unmanned Aircraft Parachute System

Parachute Systems (PS) can be readily used by small Unmanned Aircraft Systems (UAS) for risk mitigation and aircraft recovery. To date there has been limited research into the fundamental dynamics of parachutes at low Reynolds numbers, with existing studies focusing on larger parachutes. An understanding of the dynamics is needed to establish sound guidelines for parachute design and for their use during UAS operations. Existing design guidelines are reviewed and the key parachute design parameters are identified. The validity of the existing guidelines applied to lower Reynolds number parachutes is explored through a series of wind-tunnel tests. It was found that existing design guidelines underpredict the key parameters of inflation time and peak forces for parachute deployments at typical UAS operating speeds. The ramifications on the design and operation of small UAS are discussed.