Tradespace Exploration for Lightweight Multi-Application Hybrid-Electric Propulsion Systems

Electra.aero (Electra) is a rapidly growing aerospace startup company devoted to delivering feasible, innovative solutions at the nexus of advanced air mobility and the decarbonization of aviation. Electra’s mission is to develop safe, practical electric aircraft that offer the operational flexibility of a helicopter with the payload-range and low operating costs of conventional fixed wing aircraft. Electra’s first commercial product is a turbine hybrid-electric ultra-short takeoff and landing (eSTOL) aircraft designed for operations from soccer field-sizes spaces and focused on urban and regional air mobility markets. To quickly and affordably demonstrate the advantageous capabilities of hybrid-electric eSTOL aircraft, Electra developed a two-seat crewed technology demonstrator aircraft (“TD-2”), shown in Figure 1. The TD-2 conceptual design phase uncovered a lack of available commercial turbine hybrid-electric products. To solve this, Electra developed its own turbine hybrid-electric propulsion system centered around a 150 kW (200 hp) turbogenerator to power Electra’s TD-2 eSTOL demonstrator aircraft, progressing from initial concept to a successful integrated ground run (Figure 1, right) in just 12 months. Electra’s TD-2 aircraft is scheduled for first flight in October 2023 (within days of submitting this proposal), powered by the 150 kW turbogenerator. This system is also ideally suited as a power source or range extender on Group 3+ UAS (like NASA’s SUSAN subscale demonstrator aircraft) or eVTOL platforms, and has shown great promise as a lightweight, high-power portable generator for expeditionary use cases. Further, this development feat was accomplished at one-tenth the cost of a typical aerospace OEM. Electra proposes to leverage and build upon its 150 kW turbogenerator (shown in Figure 2 on the next page, designed for Electra’s 3000 lb hybrid-electric TD-2 aircraft) to address the AFWERX Prime topic interest exploring turbo-electric hybrid propulsion system design and optimization. This Phase I proposal will focus on enhancing the existing foundational modeling of Electra’s 150 kW hybrid-electric propulsion system, and then conducting trade studies on how different elements could be tweaked to provide varying levels of performance depending on the mission or performance parameter of interest. We will also develop an initial white paper framework study for design optimization of the entire hybrid system; for example, certain applications may be better suited for a diesel-electric hybrid system vs a turbine-based hybrid system, or a hydrogen fuel cell-based hybrid system vs a solar-electric system. We intend to begin the exploration of these trades in Phase I and substantially enhance and validate these models in a future Phase II effort.