Stemme S10
The Stemme S10 is a self-launching sailplane produced by Stemme AG in Strausberg (Germany) since the 1980s. The engine is mounted amidships and it features an unusual folding propeller which is stowed inside the aircraft's nose-cone when the engine is not in use. Design and development. The Stemme S10 also has several unusual features such as a tailwheel undercarriage and a side-by-side cockpit. It does not have a tow hook connection so it must self-launch. The two main wheels retract and lower electrically, though they can also be lowered manually if needed . There is an option to fold wings to reduce hangar span to . The engine restart time is 5 seconds. A solar panel can provide additional electrical power during long flights. It has a steerable tailwheel, Schempp-Hirth spoilers and optional winglets. The current variant, the S10-VT, has a variable-pitch propeller which allows more power during take off, and a new turbocharged Bombardier Rotax 914F engine in place of the earlier Limbach L2400. Most parts are made in Poland, but future production will be handled by Remos Aircraft. First seen at the 1996 Berlin Air Show, the S15 variant  has a span reduced to and has two underwing hardpoints for scientific or surveillance sensor pods. There is also an unpiloted version, the S-UAV, again intended for surveillance. Operational history. Atmospheric measurements were made with S10 VT during the Mountain Wave Project (MWP) Expedition Argentina'99 record flight to Tierra del Fuego and during Expedition Mendoza 2006, when scientific measurements of atmospheric turbulence were made up to around and over the highest mountain of the Americas, Aconcagua. An S10 was flown by Klaus Ohlmann as a pure glider for a record distance of , in a 14-hour flight. Two examples  were used by the United States Air Force Academy between 1995 and 2002 under the designation TG-11A. In December 2017, the Colombian Air Force received two Stemme S10 VTs for training purposes.