Rotax 912

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 and ultralight aircraft.

Development

The initial versions were convert|80|hp|abbr=on with convert|100|hp|abbr=on 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 convert|100|hp|abbr=on versions are used in many light sport aircraft, such as the Flight Design CTSW, the Tecnam P2002 and the Titan T-51 Mustang. The convert|80|hp|abbr=on 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 convert|100|hp|abbr=on versions) to a lower speed for the propeller.

The 912 series has a lower time between overhaul (TBO) than traditional engines but is more fuel efficient than similarly sized engines (e.g., Continental O-200).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.

Variants

The engine is available in the following versions:

* 912A# - Certified to JAA 22, 80 hp
* 912F# - Certified to FAR 33, convert|80|hp|abbr=on
* 912S# - Certified to FAR 33, convert|100|hp|abbr=on
* 912UL# - Uncertified, convert|80|Hp|abbr=on
* 912ULS# - Uncertified, convert|100|Hp|abbr=on
* 912ULSFR# - Uncertified French Authority specification. convert|100|hp|abbr=on

Where the # in the designation stands for:
# Prop shaft with flange for fixed pitch prop, P.C.D 100 mm
# Prop shaft with flange for fixed pitch prop, P.C.D 75 mm, P.C.D. 80 mm and 4" P.C.D.
# 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
# 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

pecifications (Rotax 912 UL/A/F)

pistonspecs

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 (2,4i n)
displacement=1211.2 cm³ cm³ (73, 91 cu in)
length=561 mm
diameter=
width=576 mm
height=
weight=60 kg with electric starter, carburetors, fuel pump, air filters and oil system
valvetrain=OHV, hydraulic lifters, pushrods, rocker arms
supercharger=
turbocharger=
fuelsystem=
fueltype=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.
oilsystem=dry sump with trochoid pump, camshaft driven
coolingsystem=liquid cooled cylinder heads, air cooled cylinders
power=59.6 kW @ 5800 RPM
specpower=48.71 kW/L
compression=9:1
fuelcon=15.0 liters/h @ 5000 RPM (75% power)
specfuelcon=285 g/(kW·h) @ 5500 RPM (maximum continuous power)
oilcon=
power/weight=0.98 kW/kg

pecifications (Rotax 912S ULS)

pistonspecs

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 : 2,43
bore=84 mm (3,31 in)
stroke=61 mm (2,4i n)
displacement=1352.2 cm³ cm³ (82, 6 cu in)
length=561 mm
diameter=
width=576 mm
height=
weight=60 kg with electric starter, carburetors, fuel pump, air filters and oil system
valvetrain=OHV, hydraulic lifters, pushrods, rocker arms
supercharger=
turbocharger=
fuelsystem=
fueltype=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.
oilsystem=dry sump with trochoid pump, camshaft driven
coolingsystem=liquid cooled cylinder heads, air cooled cylinders
power=73.5 kW @ 5800 RPM
specpower=54.36 kW/L
compression=9:1
fuelcon=19.8 liters/h @ 5000 RPM (75% power)
specfuelcon=285 g/(kW·h) @ 5500 RPM (maximum continuous power)
oilcon=
power/weight=1.2 kW/kg

ee also

Comparable engines:
ULPower UL260i, Jabiru 2200

References

* [http://www.rotax-aircraft-engines.com/ The official Rotax Aircraft Engines Website]
* [http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/ec342b1771dfb8d88625689600607964/$FILE/E00051EN.pdf FAA Type Certificate Data Sheet E00051EN]
* [http://home.adelphia.net/~aeroengine/Rotax.html Horizontally-Opposed Piston Aero Engines: Rotax]