Stemme AG of Strausberg, Germany (Booth 117), is showcasing its S10VT high-performance motor glider this week at EAA AirVenture 2014 in Oshkosh, Wis., on the heels of forging a manufacturing and marketing agreement with light sport aircraft OEM Remos Aircraft of Pasewalk, Germany. The S10VT, powered by a 115-hp Rotax 914 F turbocharged engine, features a patented folding propeller that enables the engine to be deployed or stowed in a matter of seconds, without changing the aircraft’s aerodynamics or center of gravity.
The aircraft is designed to self-launch, to soar as a high-performance glider (50:1 glide ratio) and serve as an efficient touring aircraft. Though certified by the FAA and first offered for sale in the U.S. more than 20 years ago, in recent years the brand has languished. Following a management change, Stemme returned to AirVenture in 2013 for the first time “in many years,” said Mark Stevenson, who in January was named president of Stemme USA, which is based in West Columbia, SC.
Given its 4.5-gph fuel burn and 140-knot top cruise speed, the company is actively marketing the S6 as a sensor platform for light ISR, such as border and shoreline patrol, Stevenson said, and eventually, the company plans to offer an autonomously piloted variant for such use.
As a motored aircraft the S10 has a service ceiling of 30,000 feet. The cabin features side-by-side seating and is outfitted with oxygen bottle holders. Optional solar panels mounted atop the fuselage aft of the cabin can power the avionics when the engine is off, and a boom microphone and crisp cabin speakers permit headset-free flying when there’s no engine noise to block.
The aircraft was developed by Dr. Reiner Stemme, a laser physicist and accomplished glider pilot who was inspired by the “wandersegelflug,” or wandering glider flight concept espoused by German glide pioneer Wolfram “Wolf” Hirth in the 1920s and 1930s. That movement led to the development of motor gliders, whose compromises as either gliders or powered aircraft Dr. Stemme sought to overcome, and the S10VT’s folding propeller was his answer.
The two spring-loaded blades lie against the propeller hub when the engine is off, nestled within the moveable nose cone. For deployment, the nose cone is opened, exposing the hub, and the engine is started, throwing the blades outward by centrifugal force.
The outboard sections of the 75.46-foot-wide wing also fold, reducing the span to about 37 feet for hangar storage, and one person can quickly fold or reconnect the wing sections. A hinged metal tube and a massive carbon fiber bolt and socket connect the center and outboards wings, held together by a locking mechanism. A recent ground and flight demonstration showcased the S10VT’s ability to perform as advertised.
Currently, the majority of parts for the composite aircraft are made by subcontractors in Poland, but manufacturing will be transferred to Remos’ factory in Pasewalk and Stemme is now the worldwide distributor of Remos aircraft under the agreement signed in June.
“Many of the people who invest in one [of the two companies] invest in the other, and it was brought to our attention that the Remos factory was underutilized,” Stevenson said. Meanwhile, with its resuscitated marketing arm, Stemme now has sales contacts worldwide. Stevenson handles North America, and Stemme AG sales and marketing director Lorenzo Costella handles the rest of the world, under the direction of CEO Paul Masschelein. Dr. Stemme is no longer involved in the company.
Production of Stemme’s S6, a motor glider with a non-retractable propeller, currently is being transferred to the Pasewalk facility and the S10VT will follow. The S10VT base price is about $400,000, and as typically equipped with LX900 gliding computer, solar panels and other options, the price is $446,000.