We offer

Two-Stroke Engines.

Two-stroke engines for unmanned aircraft, light aviation and hovercraft. Air- or liquid-cooled, on petrol or JET A-1, with free documentation for every model.

The range by output

Petrol Heavy fuel (JET A-1)

Displacement 100–650 cm³

Fuel

41036.8 hp

420212.4 hp

420113.6 hp

230149.0 hp

230249.0 hp

350757.6 hp

350370.3 hp

Showing 7 of 7 engines

41 Series

Proven in small UAVs.

Air-cooled boxer twin with closed-loop control and automatic altitude and temperature compensation.

4103

41 Series, air-cooled boxer twin

Petrol

150,000 missions behind it.

The smallest Hirth, at 4 kg. Closed-loop control with automatic altitude and temperature compensation keeps it starting and running in extreme conditions.

Power

6.8 hp

5.0 kW

Dry weight

4.0 kg

8.8 lb

Displacement

103 cm³

Boxer twin

42 Series

Twice the power, two fuels.

A compact boxer twin in the 13 hp class, on petrol or JET A-1. Closed-loop control and up to 1 kW of electrical power.

4201

42 Series, Air-cooled Boxer Twin

Petrol

13.6 hp from 7.1 kg.

Twice the output of the 41 Series in a compact boxer, with closed-loop control, altitude and temperature compensation and up to 1 kW from the starter-generator.

Power

13.6 hp

10.1 kW

Dry weight

7.1 kg

15.7 lb

Displacement

183 cm³

Boxer twin

4202

42 Series, Air-cooled Boxer Twin

Heavy Fuel

The 4201, on JET A-1.

The heavy-fuel version of the 4201, proven in extensive endurance testing. Dual ignition and up to 1 kW of onboard power for UAVs that share a fuel supply with jet aircraft.

Power

12.4 hp

9.2 kW

Dry weight

8.2 kg

18.0 lb

Displacement

183 cm³

Boxer twin

23 Series

The 50 hp class, Air-cooled.

Boxer twin with dual ignition and fuel injection, for unmanned aircraft and light manned aviation.

2301

23 Series, Air-cooled Boxer Twin

Petrol

13.6 hp from 7.1 kg.

Dual ignition and fuel injection, with an optional G23 belt reduction drive. Rated for 600 hours between overhauls.

Power

49.0 hp

36.0 kW

Dry weight

30.2 kg

66.6 lb

Displacement

521 cm³

Boxer twin

2302

23 Series, Air-cooled Boxer Twin

Petrol

49 hp and 1,000 hours to overhaul.

For light sport aircraft and motor gliders up to 120 kg, as well as hovercraft and airboats. Dual ignition and fuel injection.

Power

49.0 hp

36.0 kW

Dry weight

30.2 kg

66.6 lb

Displacement

521 cm³

Boxer twin

23 Series

Up to 70 hp, Liquid-cooled.

Inline twins with G 50 reduction gearbox options, for heavier airframes, rotorcraft and maritime UAVs.

3503

35 Series, LIQUID-cooled INLINE Twin

Petrol

70 hp at 33.5 kg.

The highest output in the range, for light aircraft, gyroplanes, helicopters and hovercraft. 1,000 hours between overhauls at 75% power, with G 50 gearbox options.

Power

70.3 hp

51.7 kW

Dry weight

33.5 kg

73.9 lb

Displacement

625 cm³

INLINE twin

3507

35 Series, LIQUID-cooled INLINE Twin

Heavy Fuel

Heavy fuel, proven at sea.

NATO-compliant, with air-assisted direct injection, electronic throttle control and an integrated 1–3 kW starter-generator. It powers the UMS Skeldar V-200.

Power

57.6 hp

42.4 kW

Dry weight

33.5 kg

73.9 lb

Displacement

625 cm³

INLINE twin

Compare all engines

Measured values from the engine datasheets. Dry weight is without exhaust.


	4103	4201	4202	2301	2302	3503	3507
Series	41	42	42	23	23	35	35
Power	6.8 hp	13.6 hp	12.4 hp	49.0 hp	49.0 hp	70.3 hp	57.6 hp
Power (kW)	5.0	10.sty	09.lut	36.0	36.0	51.7	42.4
Dry weight	4.0 kg	7.1 kg	8.2 kg	30.2 kg	30.2 kg	33.5 kg	33.5 kg
Power per kg	1.69 hp	1.90 hp	1.51 hp	1.62 hp	1.62 hp	2.10 hp	1.72 hp
Displacement	103 cm³	183 cm³	183 cm³	521 cm³	521 cm³	625 cm³	625 cm³
Layout	Boxer twin	Boxer twin	Boxer twin	Boxer twin	Boxer twin	Inline twin	Inline twin
Cooling	Air	Air	Air	Air	Air	Liquid	Liquid
Fuel	Petrol	Petrol	JET A-1	Petrol	Petrol	Petrol	Kerosene
Ignition	Single	Single	Dual	Dual	Dual	Single	Single
Starting	Starter-gen. up to 0.5 kW	Starter-gen. up to 1 kW	Starter-gen. up to 1 kW	Electric starter	Electric starter	Electric starter	Electric or ISG 1–3 kW
TBO	[confirm]	[confirm]	[confirm]	600 h	1,000 h	1,000 h at 75%	500 h
Main use	UAV	UAV	UAV	UAV	Light aviation, hovercraft	Light aviation, rotorcraft	UAV, maritime

One fuel on the flight line.

Where aircraft already run on kerosene, a petrol UAV needs its own fuel supply. The 4202 and 3507 run on JET A-1, so they refuel from the same tank as everything else on the base.

4202

12.4 hp from 8.2 kg dry. Air-cooled boxer twin for UAVs, derived from the 4201.

3507

57.6 hp from 33.5 kg dry. NATO-compliant, liquid-cooled inline twin.

Support for every engine

Documentation

Manuals and datasheets for every engine in the range, free to download.

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Technical support

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Spare parts

Request parts for any engine in the current range.

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Two-Stroke Engines.