Microturbine

Reciprocating engines can be more efficient, be cheaper overall and typically use simple journal bearings lubricated by motor oil.

[11] Researchers from the Lappeenranta University of Technology designed a 500 kW (670 hp) intercooled and recuperated two-shaft microturbine aiming for a 45% efficiency.

[12] Forecast international predicts a 51.4% market share for Capstone Turbine by unit production from 2008 to 2032, followed by Bladon Jets with 19.4%, MTT with 13.6%, FlexEnergy with 10.9% and Ansaldo Energia with 4.5%.

[14] A similar microturbine built by the Belgian Katholieke Universiteit Leuven has a rotor diameter of 20 mm and is expected to produce about 1,000 W (1.3 hp).

Direct operating costs, Turbotech says, should be reduced by 30% due to more diverse fuels and lower maintenance with a doubled time between overhaul at 4,000 h. Targeted for high-end ultralight two-seaters and unmanned aircraft, it will be slightly more expensive than a competing Rotax 912 but should be as competitive over its life cycle.

For a VTOL two-seater, a 55 kW (74 hp) turbogenerator would weigh 85 kg (187 lb) with fuel for 2.5 h of endurance instead of 1 ton of batteries.

[needs update] The final assembly line was created in Toussus-le-Noble Airport near Paris, for a 1,000-engine annual output by 2025.

The 64 kg (141 lb) TP-R90 turboprop or TG-R90 turbogenerator can output 90 kW (120 hp) and burns 18–25 L (4.8–6.6 US gal) of jet fuel per hour in cruise.

[16] Czech PBS Velká Bíteš offers its 180 kW (240 hp) TP100 turboprop weighing 61.6 kg (136 lb) for ultralights and UAVs, consuming 515 g/kWh (5.05 oz/MJ).

The batteries act as a "buffer" (energy storage) in delivering the required amount of power to the wheel motors, rendering throttle response of the gas turbine irrelevant.

It was this poor throttling response that so bedeviled the 1950 Rover gas turbine-powered prototype motor car, which did not have the advantage of an intermediate electric drive train to provide sudden power spikes when demanded by the driver.