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Rotax 912UL 80 hp (60 kW) installation in a 3Xtrim 3X55 Trener

Rotax 912ULS 100 hp (75 kW) installation in a Blue Yonder Merlin EZ

Pusher engine installation of two Rotax 912ULSs in a Leza-Lockwood AirCam

The Rotax 912 is a normally-aspirated, air- and water-cooled, horizontally-opposed, four-cylinder, four-stroke, gear reduction-drive engine commonly used on certified aircraft, light sport aircraft, ultralight aircraft and unmanned aerial vehicles.

[edit] Development

The initial versions were 80 hp (60 kW) with 100 hp (75 kW) variants added later, using higher compression ratios and different parts to achieve the increase in power. The 912A is used in certified aircraft such as the Diamond DA20-A1 Katana, which is quite popular in Europe. The 100 hp (75 kW) versions are used in many light sport aircraft, such as the Flight Design CTSW, the Tecnam P2002 and the Titan T-51 Mustang. The 80 hp (60 kW) versions are sufficient to overpower the new generation of efficient motorgliders, such as the Pipistrel Sinus and the Urban Air Lambada.

The engine is different from conventional aircraft engines (such as the Lycoming O-235) in that it has air-cooled cylinders with water-cooled heads and uses a gearbox to reduce the engine's relative high shaft speed (5,800 rpm for 100 hp versions) to a lower speed for the propeller.

The 912 series have a lower time between overhaul (TBO) than traditional engines but are more fuel efficient than similarly sized engines (e.g., Continental O-200). Effective 14 December 2009 912 engines have had their recommended TBO raised from 1200 hours to 1500 hours.^[1] In addition to the lower fuel consumption they are certified to run on automotive fuel (Mogas) further reducing running costs. The engines are very popular in Europe due to the lower fuel consumption and lower noise generated.

[edit] Variants

The engine is available in the following versions:

• 912A# - Certified to JAA 22, 80 hp (60 kW)
• 912F# - Certified to FAR 33, 80 hp (60 kW)
• 912S# - Certified to FAR 33, 100 hp (75 kW)
• 912UL# - Uncertified, 80 hp (60 kW)
• 912ULS# - Uncertified, 100 hp (75 kW)
• 912ULSFR# - Uncertified French Authority specification. 100 hp (75 kW)

Where the # in the designation stands for:

1. Prop shaft with flange for fixed pitch prop, P.C.D 100 mm
2. Prop shaft with flange for fixed pitch prop, P.C.D 75 mm, P.C.D. 80 mm and 4" P.C.D.
3. Prop shaft with flange for constant speed propeller P.C.D. 75 mm, P.C.D. 80 mm, P.C.D 4" and drive for hydraulic governor for constant speed propeller
4. Prop shaft with flange for constant speed propeller P.C.D. 75 mm, P.C.D. 80 mm, P.C.D 4" and prepared for retrofit of a hydraulic governor for constant speed propeller

[edit] Applications

• 3I Sky Arrow
• 3Xtrim 3X55 Trener
• Advanced Aeromarine Buccaneer II
• Aero Adventure Aventura II & XLR
• ASAP Chinook Plus 2
• Blue Yonder Merlin
• CZAW SportCruiser
• Denney Kitfox
• Diamond DA20-A1 Katana
• Fisher Dakota Hawk
• InterPlane Skyboy
• General Atomics MQ-1 Predator
• ICON A5
• Leza-Lockwood AirCam
• Lockwood Super Drifter
• Remos GX
• Skyleader Aircraft Skyleader 100
• Urban Air Samba

[edit] Specifications (Rotax 912 UL/A/F)

General characteristics

• Type: 4-cylinder, 4-stroke liquid / air cooled engine with opposed cylinders, dry sump forced lubrication with separate oil tank, automatic adjustment by hydraulic valve tappet, dual CD carburetors, mechanical diaphragm pump, electronic dual ignition, electric starter, integrated reduction gear 1 : 2.273
• Bore: 79.5 mm (3.13 in)
• Stroke: 61 mm (2.40 in)
• Displacement: 1,211.2 cm³ (73.91 in³)
• Length: 561 mm (22.1 in)
• Width: 576 mm (22.7 in)
• Dry weight: 60 kg (132.3 lb) with electric starter, carburetors, fuel pump, air filters and oil system

Components

• Valvetrain: OHV, hydraulic lifters, pushrods, rocker arms
• Fuel type: unleaded: 87 octane AKI (Canada/USA) / 90 octane RON (European) or higher. Leaded fuel and AVGAS 100 LL can be used but are not recommended.
• Oil system: dry sump with trochoid pump, camshaft driven
• Cooling system: liquid cooled cylinder heads, air cooled cylinders

Performance

• Power output: 59.6 kW (79.9 hp) @ 5,800 rpm
• Specific power: 48.71 kW/L
• Compression ratio: 9:1
• Fuel consumption: 15.0 liters/h @ 5,000 rpm (75% power)
• Specific fuel consumption: 285 g/(kW·h) @ 5,500 rpm (maximum continuous power)
• Power-to-weight ratio: 0.98 kW/kg

[edit] Specifications (Rotax 912S ULS)

General characteristics

• Bore: 84 mm (3.31 in)
• Stroke: 61 mm (2.4 in)
• Displacement: 1,352.2 cm³ (82.5 in³)
• Length: 561 mm
• Width: 576 mm
• Dry weight: 60 kg with electric starter, carburetors, fuel pump, air filters and oil system

Components

• Valvetrain: OHV, hydraulic lifters, pushrods, rocker arms
• Fuel type: unleaded: 87 octane AKI (Canada/USA) / 90 octane RON (European) or higher. Leaded fuel and AVGAS 100 LL can be used but are not recommended.
• Oil system: dry sump with trochoid pump, camshaft driven
• Cooling system: liquid cooled cylinder heads, air cooled cylinders

Performance

• Power output: 73.5 kW (98.6 hp) @ 5,800 rpm
• Specific power: 54.36 kW/L
• Compression ratio: 9:1
• Fuel consumption: 19.8 L (5.2 US gal)/h @ 5,000 rpm (75% power)
• Specific fuel consumption: 285 g/(kW·h) @ 5,500 rpm (maximum continuous power)
• Power-to-weight ratio: 1.2 kW/kg

[edit] See also

• ULPower UL260i
• Jabiru 2200
• List of aircraft piston engines

[edit] References

• The official Rotax Aircraft Engines Website
• FAA Type Certificate Data Sheet E00051EN
• Horizontally-Opposed Piston Aero Engines: Rotax