Flight Design, GmbH, is developing from a standard Rotax 914 engine, an electric augmented powerplant that will produce an extra 40 hp for short (less than three minute) bursts of power. The company has “specifically developed for this task” an electric motor that is coupled to the prop hub through a belt drive. The goal of the concept is to produce an engine capable of fulfilling the role of a 160-to 180-hp normally aspirated engine without the larger engine’s emissions. Mated to the turbocharged Rotax, the Hybrid Concept Engine will not readily lose power at altitude, flying efficiently in cruise, while enjoying the electric motor’s extra boost during takeoff and initial climb. Batteries for the unit are based on Lithium Iron Phosphate chemistry and are quick-chargeable. Operation of the engine is designed for one-lever control, with a controller module selecting thrust from the electric motor only when the reciprocating engine is operating at more than 90 percent above available power. Otherwise, the reciprocating engine works to recharge the motor’s batteries in flight, which causes “negligible” resistance on the crankshaft, according to the company.
Aside from lowering emissions per horsepower, the power of the electric motor alone “is enough to supplant a stopped engine,” but only well enough to extend a glide and provide more options to a pilot in emergency. A proof of concept Hybrid Power Engine has been built and bench tests are ongoing. So far, says Flight Design, those tests “have underlined the correctness of all assumptions.” Flight Design is a 23-year-old company based in Germany. It has produced more than 1,300 aircraft that are flying in 25 countries, including the very popular CT LSA.
