Emrax 207

Emrax 207
Type	Electric aircraft engine
National origin	Slovenia
Manufacturer	Emrax
Unit cost	€3,069 (2015)

Last updated March 30, 2019

The Emrax 207 is a Slovenian electric motor for powering electric aircraft and other applications, designed and produced by Emrax d.o.o of Kamnik. The company was formerly called Enstroj and based in Radomlje.^[1]

Slovenia, officially the Republic of Slovenia, is a sovereign state located in southern Central Europe at a crossroads of important European cultural and trade routes. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the southeast, and the Adriatic Sea to the southwest. It covers 20,273 square kilometers (7,827 sq mi) and has a population of 2.07 million. One of the successor states of the former Yugoslavia, Slovenia is a parliamentary republic and a member of the United Nations, of the European Union, and of NATO. The capital and largest city is Ljubljana.

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of rotation of a shaft. Electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. An electric generator is mechanically identical to an electric motor, but operates in the reverse direction, converting mechanical energy into electrical energy.

An electric aircraft is an aircraft powered by electric motors. Electricity may be supplied by a variety of methods including batteries, ground power cables, solar cells, ultracapacitors, fuel cells and power beaming.

Design and development

The Emrax 207 is a brushless design producing 70 kW (94 hp), with an outrunner coil. The low working rpm of the engine means that it can turn a propeller at efficient speeds without the need for a reduction drive.^[1]

A brushless DC electric motor, also known as electronically commutated motor and synchronous DC motors, are synchronous motors powered by DC electricity via an inverter or switching power supply which produces an AC electric current to drive each phase of the motor via a closed loop controller. The controller provides pulses of current to the motor windings that control the speed and torque of the motor.

A reduction drive is a mechanical device to shift rotational speed. A planetary reduction drive is a small scale version using ball bearings in an epicyclic arrangement instead of toothed gears.

Specifications (Emrax 207)

Data from Tacke^[1]

General characteristics

Type: Brushless electric aircraft engine
Length: 85 mm (3.3 in)
Diameter: 207 mm (8.1 in)
Dry weight: 9 kg (19.8 lb)

Aircraft engine Engine designed for use in powered aircraft

An aircraft engine is a component of the propulsion system for an aircraft that generates mechanical power. Aircraft engines are almost always either lightweight piston engines or gas turbines, except for small multicopter UAVs which are almost always electric aircraft.

Components

Coil type: Outrunner
Cooling system: air
Reduction gear: none

An electromagnetic coil is an electrical conductor such as a wire in the shape of a coil, spiral or helix. Electromagnetic coils are used in electrical engineering, in applications where electric currents interact with magnetic fields, in devices such as electric motors, generators, inductors, electromagnets, transformers, and sensor coils. Either an electric current is passed through the wire of the coil to generate a magnetic field, or conversely an external time-varying magnetic field through the interior of the coil generates an EMF (voltage) in the conductor.

The term outrunner refers to a type of brushless DC electric motor primarily used in electrically propelled, radio-controlled model aircraft.

A propeller speed reduction unit is a gearbox or a belt and pulley device used to reduce the output revolutions per minute (rpm) from the higher input rpm of the powerplant. This allows the use of small displacement internal combustion automotive engines to turn aircraft propellers within an efficient speed range.

Performance

Power output: 70 kW (94 hp)
Power-to-weight ratio: 7.8 kW/kg

Power-to-weight ratio is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power source. It is also used as a measurement of performance of a vehicle as a whole, with the engine's power output being divided by the weight of the vehicle, to give a metric that is independent of the vehicle's size. Power-to-weight is often quoted by manufacturers at the peak value, but the actual value may vary in use and variations will affect performance.

References

1 2 3 Tacke, Willi; Marino Boric; et al: World Directory of Light Aviation 2015-16, pages 262–263. Flying Pages Europe SARL, 2015. ISSN 1368-485X
↑ Emrax. "EMRAX". emrax.com. Retrieved 29 April 2018.

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[WDLA15-1] 1 2 3 Tacke, Willi; Marino Boric; et al: World Directory of Light Aviation 2015-16, pages 262–263. Flying Pages Europe SARL, 2015. ISSN 1368-485X

[2] Emrax. "EMRAX". emrax.com. Retrieved 29 April 2018.