Problem
Dr. Jayant Sirohi and his team have developed an autorotative payload decelerator device that can be dropped from any type of aircraft at high speeds. Dr. Sirohi is the M.J. Thompson Regents Professorship in Aerospace Engineering & Engineering Mechanics and the Principal Investigator of the Vertical Lift Research Center of Excellence funded by the U.S. Army and Navy at UT Austin with primary interests in active materials/sensors/actuators, smart/multifunctional structures, energy harvesting, micro/UAV, vertical lift aircraft, fixed wing/rotary wing aeroelasticity, and experimental aerodynamic/structural dynamics. He has authored/co-authored numerous journal articles and was named a Technical Fellow of the Vertical Flight Society (VFS) for 2021. The focus of his work has broad applicability in the development of next-generation vertical take-off aircraft and performance enhancements of existing rotorcraft using advanced technologies.
Solution
A compact, autorotative decelerator device has been developed for carrying a payload that can be dropped from any aircraft traveling at high speeds. The system uses a passive, stowable, rotary wing decelerator with a 406 mm rotor diameter, which slows down the rate of descent of the device, allowing it to be precisely steered to a desired ground target location. The technology allows for high-speed payload launch from a 1″×1″×8″ tube with a total system weight of 100-200 grams and provides steady-state descent velocities of 3-5 m/s. The delivery system uses a unique double-flap hinge design, including large negative pitch-flap coupling angles for reliable rotor deployment and spin-up.
Prototype wind tunnel testing demonstrated a rotor effective drag coefficient of ~1.4, equivalent to that achieved using hollow hemisphere parachutes of the same diameter. An instrumented prototype rotor system was flight evaluated in a series of drop and high-speed deployment tests. These indicated that the rotor decelerator could be successfully deployed in all conditions, including a high-speed tumble realizing a stable autorotation. Available autorotative payload decelerator devices can deploy rotor blades but cannot realize a controlled descent towards a ground target, resulting in the aircraft having to be slowed down for accurate payload delivery. The developed technology can deliver a payload without slowing down the speed of the aircraft, resulting in safer/more efficient payload delivery.
The inventors are investigating the development of guidance and control software that could enable more precise device steering to the ground target location. The system has potential application in both the military and civilian markets where accurate delivery of a payload to a ground location from an aircraft is required.
