A three-cylinder, opposed piston two-stroke diesel engine may seem like a strange configuration, but Derek Graham, chairman of the U.K.-based Powerplant Developments, says the design has been around in aircraft since the 1930s. His engineering team believed the concept could be updated with new technology and deliver a high weight-to-power ratio. “Everyone wanted an engine that would deliver 100 horsepower at a 150 pounds, but it was thought to be impossible,” he said. The new Gemini engine delivers 100 hp at 166 pounds installed, according to Graham. “And the design eliminates the need for a camshaft, valve gear and cylinder head joints — three main causes of unreliability and high maintenance costs of older-generation piston engines,” he said.
Timothy Archer, president and CEO of the company, said the engine will be marketed to the experimental market by next spring, and then for the LSA market via the ASTM process by the end of next year. Both FAA and EASA certification are planned for the future. In addition, larger versions of the engine, including a four cylinder, are possible.
