If you’ve ever fooled around with a gravity knife, you can imagine the eureka moment Dr. Reiner Stemme likely experienced while trying to develop a motorglider providing both uncompromising soaring and outstanding powered performance. Imagine a prop’s blade rather than a knife’s flicking out from the handle, and you’ll understand how a propeller that looks like it’s too big to fit pops out of the nose of the Stemme S10. It’s the high-performance motorglider that Dr. Stemme quit his day job as a laser physicist to create. The patented breakthrough allows the S10 to switch between powered and unpowered flight in seconds with no aerodynamic penalty or change in the aircraft’s center of gravity.
The S10 has been FAA certified and flying in the U.S. for more than 20 years, but in an era looking for lean and green solutions, it seems like the Stemme’s time has come. Its 115 hp Rotax 914 engine gives it a popular and efficient powerplant, the 50:1 glide ratio makes the Stemme capable of both high-performance glider competition and cross-country soaring, and today’s gliding computers and onboard weather products make it easier to find and exploit lift. That’s probably why Berlin-based Stemme AG is putting renewed focus on the U.S. market. Mark Stevenson, newly appointed president of Stemme USA in Lyons, Colo., and Andreas Hebner, Stemme AG’s Germany-based demonstration pilot, invited P&P to meet up at Maryland’s Frederick Municipal Airport (FDK) for a “soaring safari,” an Anglicism the Germans coined decades before the Beach Boys ever planted the idea of setting off in search of waves. Hebner had flown N137VT, an S10-VT—the turbocharged S10 variant—from Columbia, S.C., the previous day, and its wings were still folded back from its night in a hangar.