UAV EFI kits engine control unit

The UAV EFI kit from Ecotrons (EcoEFI) is an engine control unit and electronic fuel injection system for small multi-cylinder unmanned-aircraft engines, controlling both fuel injection and ignition on one- and two-cylinder engines. It replaces the carburetor on small two-stroke, four-stroke and similar UAV engines and gives the integrator a closed electronic engine-management loop in place of a mechanical fuel metering device.

The kit is aimed at engines of the 20 cc to 200 cc class and some larger ones up to the 600 cc range, the typical size for fixed-wing and hybrid-propulsion UAVs. The maker states that its kits have been fitted to popular engines such as 3W, Desert Aircraft and DLE units, with installation manuals available for specific engine models. The stated benefit of fuel injection over a carburetor is fuel economy, with the maker reporting a 30% to 50% improvement on typical UAV engines, plus more stable operation in hot, cold and humid conditions and at altitude.

The ECU has an aluminium case, weighs 120 grams and measures 78 x 64 x 20 mm. It uses a 37-pin mini-D connector, has a built-in barometric pressure sensor for automatic altitude compensation, and is CAN bus capable, so it can exchange data with the flight controller or other avionics. It supports up to two cylinders with fuel injection and ignition control, and the kit supports throttle-by-wire operation, in which the ECU reads the servo position and can drive the throttle servo itself.

The rest of the kit is sized for small airframes. The micro gear pump weighs 110 grams, measures 34 mm in diameter by 76 mm in length, draws 0.5 A to 2 A, and is self-priming. The small injectors weigh 20 grams, measure 15.8 mm in diameter by 40 mm in length, and have a flow rate of 30 g/min, which suits engines down to 20 cc. Throttle bodies come in bore sizes from 14 mm to 34 mm and weigh 55 g (14 mm), 60 g (18 mm), 70 g (22 mm) and 80 g (28 mm); they are direct replacements for Walbro carburetors of 10 mm to 34 mm bore, and can be combined with the servo motor so that a separate throttle position sensor is not needed.

Optional single- or dual-channel CDI ignition units weigh 120 g and are programmable through the ECU. The maker supplies a custom lightweight harness built for harsh environments, together with tuning software (EcoCAL), a CAN protocol document for UAVCAN, an installation manual and an EFI tuning guide.

Typical applications are long-endurance fixed-wing UAVs, gasoline-powered multirotors and range-extender engines that carry cameras or other sensors and fly for several hours at altitude, where reliability, low electrical consumption and low mass of the engine-management system matter.