Emerging eVTOL and urban air mobility technologies enable numerous use cases for highly maneuverable aircraft without the traditional capital and land intensive requirements of airports and runways. Many of the proposed and in-development designs consist of smaller distributed propellers driven by electric motors. Some, but not all, also have lifting surfaces to improve efficiency in forward flight. While these design features enable many commercial use opportunities, they also have drawbacks. Perhaps most significantly when considering their proposed use in densely populated urban areas is their limited ability to perform emergency landings under catastrophic power system failure. Unlike traditional helicopters, their rotors are not large enough to autorotate to the ground. Unlike airplanes, their gliding surfaces may not be sufficient to glide to the ground. These same challenges remain for any Defense use of eVTOL technologies and aircraft. Earthly Dynamics Corporation (EDC), teamed with the Aerial Robotics and Experimental Autonomy Lab (AREAL) Lab at the Georgia Institute of Technology, proposes the development of a recovery system for eVTOL aircraft that uses a gliding, steerable parachute. This system will be built by leveraging EDCs extensive expertise in bleed-air control and experience developing novel control hardware for U.S. Army airdrop applications combined with AREALs expertise developing parafoil guidance and emergency landing reachability algorithms. Our proposed solution will continuously generate feasible landing paths throughout normal flight using AREALs GPU-accelerated massively parallel planning algorithms which operate under explicit uncertainty to provide better assurance of feasibility. Upon power failure, our parafoil would deploy and guide the aircraft slowly down to a pre-approved emergency landing area. For any aircraft, but especially eVTOL aircraft with the limited energy density of current battery technology, weight is critical. Whereas traditional guided parafoil systems steer by using large actuators to deform the canopy via the trailing edge lines, EDCs in-canopy actuators vent pressurized ram air through the top surface of the canopy, disrupting airflow and controlling the canopy. Because they only actuate against the ram air, the force and power requirements are vastly reduced. This has a large leveraging effect on the total size and weight of the system, since the motor, control electronics, wiring, battery, battery management and charging hardware are all much smaller. For one prototype in-canopy guidance system which EDC developed, the total weight of the guidance hardware was about 40% of the weight of the parafoil itself, and <2% of the payload weight. These percentages scale even better at larger scale. This means that using our in-canopy guidance and control approach, a guided recovery system can be achieved for very close to the same weight as a ballistic emergency parachute.
