Rotax 912

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Type Piston aircraft engine
National origin Austria
Manufacturer Rotax Aircraft Engines
Major applications Light sport aircraft
Ultralight aircraft
Variants Rotax 914
Rotax 912ULS 100 hp (75 kW) installation in a Blue Yonder Merlin EZ
Pusher engine installation of two Rotax 912ULSs in a Lockwood Aircam
Rotax 912ULS with tuned exhaust in a Dyn'Aéro MCR01 with 3-blade hydraulic CSU propeller.

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.

Development

The original 80 hp (60 kW) 912 engine has a capacity of 1,211 cc (73.9 cu in) and a compression ratio of 9.1:1. The later 912S is enlarged to 1,352 cubic centimetres (82.5 cu in) and has a compression ratio of 10.4:1, yielding 100 hp (75 kW). The 912 A and F are used in certified aircraft, such as the Diamond DA20, 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 Sierra and the Titan T-51 Mustang. The 80 hp (60 kW) versions are sufficient to power the new generation of efficient motorgliders, such as the Pipistrel Sinus and the Urban Air Lambada. It is also fitted to some light twins, such as the Tecnam P2006T.

The engine differs from conventional aircraft engines (such as the Lycoming O-235) in that it has air-cooled cylinders with liquid-cooled heads and uses a 2.43:1 gearbox (PSRU) to reduce the engine's relative high 5,800 rpm shaft speed to a more conventional 2,400 rpm for the propeller. Lubrication is dry sump, and fuelling is via dual CV carburetors or fully redundant electronic fuel injection.

Early 912 series engines have a shorter 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 Time Between Overhauls (TBO) raised from 1,200 hours to 1,500 hours, or 1,500 hours to 2,000 hours, depending on serial number.[1] In addition to the lower fuel consumption they are certified to run on automotive fuel (mogas), further reducing running costs, especially in areas where leaded AVGAS is not readily available. The engines are popular in Europe and in United States Light Sport Category aircraft due to high power-to-weight ratio, low fuel costs and relatively quiet operation.

On 8 March 2012 the company displayed its new 912 iS variant, a 100 hp (75 kW) version with direct fuel injection and an electronic engine management unit.[2] The new version weighs 63 kg (139 lb), which is 6 kg (13 lb) more than the standard 912S. The non-certified 912 iS targets the Light Sport and Experimental market and 912 iSc will be certified. Production started in March 2012 and the new engine has a 2000 hour recommended time-between-overhaul to start.[3]

Variants

The engine is available in the following versions:

912 A#
Certified to JAR 22, 80 hp (60 kW)
912 F#
Certified to FAR 33, 80 hp (60 kW)
912 iS
Uncertified, 100 hp (75 kW) with direct fuel injection and an electronic engine management unit[3]
912 iSc
Certified, 100 hp (75 kW) with direct fuel injection and an electronic engine management unit[3]
912 S#
Certified to FAR 33, 100 hp (75 kW)
912 UL#
Uncertified, 80 hp (60 kW)
912 ULS#
Uncertified, 100 hp (75 kW)
912 ULSFR#
Uncertified French Authority specification. 100 hp (75 kW)

The # in the designation stands for:

  1. Shaft with flange for fixed pitch propeller, P.C.D. 100 mm
  2. Shaft with flange for fixed pitch propeller, P.C.D. 75 mm, P.C.D. 80 mm and P.C.D. 4 inches
  3. Shaft with flange for constant speed propeller P.C.D. 75 mm, P.C.D. 80 mm, P.C.D. 4 inches and drive for hydraulic governor for constant speed propeller
  4. Shaft with flange for fixed speed propeller P.C.D. 75 mm, P.C.D. 80 mm, P.C.D. 4 inches also can be fitted with an adaptor, drive and governor for a constant speed propeller.

Applications

Specifications (Rotax 912 UL/A/F)

General characteristics

  • Type: four-cylinder, four-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 or 1 : 2.43
  • 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

See also


Comparable engines
Related lists

References

  1. ↑ Rotax (December 2009). "Extension of Time Between Overhauls (TBO) for Rotax Engine Type 912 and 914 (Series)". Retrieved 2010-02-11. 
  2. ↑ "Rotax Introduces 921iS". Sport Aviation: 14. May 2012. 
  3. ↑ 3.0 3.1 3.2 Bertorelli, Paul (8 March 2012). "BRP/Rotax Rolls Out New Engine". AVweb. Retrieved 14 March 2012. 
  4. ↑

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