Application of Hybrid-Electric Propulsion to ‘Very Light Jet’ Business Aircraft

The following paper investigates the feasibility of hybrid-electric propulsion (HEP) for a very light jet (VLJ) business aircraft based on predictions of battery performance for the 15-year timeframe to 2040. Given the unique requirements of a range of between 1100 and 2200 km (600 and 1200 nmi) and a cruise speed of around Mach 0.65, this paper utilizes a time-stepping simulation to determine range for a baseline aerodynamic model over combinations of energy hybridization ratios and battery specific energy densities of HE∈[0.0,0.25] and ebat∈[400,1250] Wh/kg for series and parallel architectures. The paper also analyzes fuel and battery energy consumption, battery weight and volume, and finally a typical mission of 1111 km (600 nmi). The results of the paper find that the parallel architecture is better suited to application on very light jets, as it enables a greater maximum range of 1394 km (754 nmi) with a mild energy hybridization of 5% and a battery specific energy density of 1250 Wh/kg for a fixed maximum takeoff weight. Over a typical 1111 km (600 nmi) mission, fuel savings with a parallel architecture are 96 kg (212 lbs) compared to a conventional turbofan, or 7.1% of the total fuel load. Consequently, it is recommended that a hybrid-electric very light jet utilize a mild-hybrid parallel architecture of around 5% energy hybridization and batteries of at least 1250 Wh/kg.