G Warwick, Plug to play, Aviation Week & Space Technology, 20 August-2 September 2018, p 46
In US, a summary of the possible future of aircraft propulsion appears as follows:
- Short range general aviation - piston engines
- Regional and business aviation - turboprops and small turbofans
- Medium and long-haul commercial air transport - large turbofans
Clean, quiet, reliable electric propulsion could well suit the first category, and hybrid-electric propulsion the second, both of which are achievable with today’s technology. Electrifying the third category will involve further development of the energy density of batteries, power density of generators, inverters and motors, plus the management of heat flow, high voltages and distributed propulsion. Research is already showing potential improvements of up to 20% in fuel burn for hybrid-electric aircraft following developments by the United Technology Research Center, Safran, Airbus, Siemens, Rolls-Royce, Embraer and others.