Flight and Power Control Systems Development for a Turbine-Hybrid DEP eSTOL Aircraft

Electra is developing a hybrid-electric ultra-short takeoff and landing (eSTOL) aircraft for commercial advanced air mobility markets which also offers strong dual-use capabilities for defense missions. Electra’s commercial product aircraft leverages distributed electric propulsion and blown lift to efficiently transport seven to nine passengers (1,800 lbs of payload) up to 500 nautical miles with takeoff ground rolls of only 150 feet. Electra is planning a commercial entry into service date of 2026 under FAA Part 23 regulations. As a risk reduction milestone to reaching the product, Electra is currently building a 2-seat, 3,000-lb gross weight hybrid-electric STOL technology demonstrator aircraft (“TD-2”), which is expected to achieve first flight in late 2022. To achieve the differentiating ultra-STOL takeoff and landing capability outlined above, precise flight control at very low forward speeds is required, where conventional aerodynamic control surfaces are ineffective and wind gusts are a relatively large proportion of the vehicle speed.  This makes the design and precision of the flight control system a key challenge, especially since many target landing locations have very small footprints. The distributed electric blown wing configuration offers a unique opportunity to greatly increase low speed control authority by integrating rapid response rate electric motors into the lateral and longitudinal control systems. The large number of motors and complex aeropropulsive coupling effects make this an even more challenging problem to solve.  Related to this is the challenge of developing the control system for the hybrid powertrain, which determines the power allocation between the turbine and the battery as well as handles failure or off-nominal system states.  Due to the large numbers of electrical components in the powertrain and the complexity of potential failure modes, this requires the development of more sophisticated on-board energy management systems. This SBIR proposal is focused on the development of a new approach to highly responsive low speed flight control and hybrid systems power management. First, an accurate piloted eSTOL simulator will be developed to help design and test a novel integrated flight control system, pilot control strategies, and motor control integrations. Enhanced pilot displays that show the operational state of the hybrid system and aid landing precision will also be developed. The resultant novel flight control system will be implemented and tested in a HILSIM and integrated into Electra’s ultra-STOL technology demonstrator aircraft described above.