D250 electric motor

The D250 is a liquid-cooled electric motor for aircraft propulsion and power generation, developed and manufactured by Evolito. It is a high-voltage electric motor intended for electric and hybrid-electric aircraft, and its performance is optimised for the shaft speeds typical of rotorcraft.

Evolito designs the D250 as a lightweight, compact package. The published figures are a peak power of 180 kW, a maximum speed of 10,000 rpm and a mass of 14.5 kg. Dividing peak power by mass gives roughly 12.4 kW per kilogram, a ratio that matters when sizing propulsion for multirotors, eVTOL aircraft and other platforms where every kilogram of motor mass reduces payload or range.

The motor body is cylindrical, 370 mm in diameter and 125 mm long. This short, wide shape suits direct mounting on a rotor shaft or on a gearbox input and gives a different packaging footprint from long, narrow motors. Cooling is by liquid. Evolito gives the reason as a controlled thermal environment for long periods at high power in a small machine, avoiding the aerodynamic and performance costs of air-cooled designs. The integrator therefore needs a coolant loop with pump and heat exchanger in the airframe.

In the system, the D250 is built to work with Evolito's MC350 motor controller as part of an aerospace-grade power system. The company states that its motors are used for propulsion and also for generation, so the same machine can serve as a drive motor or as the generator side in a hybrid architecture, coupled to an engine, gearbox and electrical system. More power can be reached by stacking several D250 or D500 motors in a common, scalable architecture, which is useful when one motor does not cover the required shaft power for a larger rotorcraft or lifting platform. Evolito states a design maintenance interval of 5,000 flight hours for its electric engines.

Typical applications are hybrid-electric and fully electric propulsion for eVTOL aircraft, large unmanned rotorcraft and other aircraft that operate at rotorcraft speeds, as well as generator duty in hybrid powertrains.