! 2743 KERO Rotary engine technology takes off in general aviation The EUREKA E! 2743 KERO project is driv- ing key Federal Aviation Authority (FAA) certification for Wankel rotary engines in general aviation. Swiss project leader Mistral Engines plans to supply a range of such engines for original equipment and retrofitting in all types of light airplanes and helicopters. Advantages include excellent reliability as there are few moving parts, a high power-to- weight ratio, compactness and smooth running compared with conventional piston engines. Moreover, the engine will run on widely available jet fuel. Oth- er potential applications include marine engines as well as light industrial ap- plications such as portable generators, compressors and pumps. The four-stroke piston engine technology used in the majority of light airplanes involved in general aviation dates back 60 years to the Second World War. So, while designs are well proven, motors require some 70 or 80 moving parts and still run on 100-octane low- leaded (100 LL) avgas fuel that has long been displaced by heavier kerosene- based jet fuel for commercial aircraft. Moreover, 100 LL fuel is mostly limited to North America and Europe; even there it is becoming increasingly scarce – and is soon to be banned completely for environmental reasons. Mistral Engines therefore saw a major market for a safer, more reliable motor that could be easily adapted to any model of light aircraft and able to run on industry standard jet fuel. The design is based on the Wankel rotary engine pioneered originally in Germany in the 1930s but which emerged at the wrong time. So far, it has only really been developed and commercialised by Japanese car maker Mazda in its RX-8 models and previous models. Few moving parts Safety and reliability are key factors in aviation. The Wankel engine has a rotor instead of reciprocating pistons, doing away with any need for crankshafts, pistons, valves and springs and reducing the number of moving parts to only two or three very robust ones. With so few moving parts, the engine is extremely reliable and safe. However, the rotary engine is difficult to run in a fuel efficient manner. Recently, the availability of modern automotive electronics has made it possible to overcome timing and injection control complications, resulting in fuel consumption similar to that of piston engines. Rotary engines for small planes are not completely new. Many amateurs in the USA have adapted car engines for this purpose. It is actually a technology particularly well fitted to aviation applications. “We therefore decided to take the Mazda rotary engine block and to build an aero engine around it that could be retrofitted to all aircraft, explains Claude Geles, one of Mistral Engines co-founders. “Mounting an engine in an aircraft is a delicate process and very expensive. We also had to design a suitable gearbox. Modern electronics now make it possible to have exact timing for fuel injection and ignition. The resulting engine looks like a turbine; it is not really a turbine but EUREKA labelling enabled us to find the 10 million euro in private equity financing that we needed to see the project safely through to a fully certified product ready for manufacture. Claude Geles - Mistral Engines, Switzerland Advances in combustion chamber design and electronic management systems are making it possible to develop a reliable rotary engine for small planes running on standard kerosene jet fuel Shaping tomorrow’s innovations today