UK joint venture Powerplant Developments is promising savings of more than $100,000 over 2,000h of operations with its new liquid cooled, two-stroke, three-cylinder, twin crankshaft, diesel Gemini engine series for light sports aircraft.
The engine is now available to private buyers and original equipment manufacturers as an experimental engine. Approval from standards body ASTM is planned for November 2008.
The Gemini 100 is named after its twin half-length crankshafts, which are made of EN40 grade steel for greater torsional stiffness, and its 100hp (75kW) output.
A geared engine, the Gemini's two crankshafts are linked by a gear train to achieve the 4,000rpm that will turn the centrally mounted propeller at 2,500rpm with a torque of 285Nm (210lb/ft).
With a claim of a power-to-weight ratio higher than its nearest competitors, Powerplant Developments argues that its fuel-injected Gemini 100 will have a specific fuel consumption of 0.24kg/h/kW (0.41lb/hp/h) at a cruise setting of 75% power at 5,000ft (1,520ft).
The company says Gemini 100 will have an hourly fuel consumption of 18 litres/h (4.75USgal/h] of Jet-A, compared with the 25 litres/h of avgas required by a typical Rotax 912 engine.
Powerplant Developments claims the four-stroke Rotax 912 S engine costs $170,000 over 2,000h of operations, while its Gemini 100, which it says has a time-before-overhaul of 2,000h, will cost $67,000.
As well as diesel and Jet-A, biodiesel is under investigation for the Gemini series.
The current engine is capable of 100hp output from sea level, up to 5,000ft with its supercharger, and there are plans for 125 and 200 series engines. The Gemini 125, aimed for a July 2009 release, is also supercharged. It will be available as an experimental engine in November 2008.
Designed to fit existing Light Sport Aircraft installations, the Gemini 100 engine has a 70kg (155lb) dry mass, including starter and alternator. With its hoses, fittings and heat exchanger that mass increases by another 5kg.
It does not use full-authority engine digital control, but the company expects to incorporate FADEC for higher horsepower engines.
Powerplant Developments is a joint venture between Sussex, UK-based Jade Air and Weslake Air Services.
The Gemini series will be made by Jade Air until Powerplant Developments' facility is completed.
Source: Flight International
