Stemme S12: Sound of Silence

Stemme S12: Sound of Silence

Stemme S12

The Stemme S12 combines the best attributes of a glider with the convenience of powered flight, in one sleek package.

Is the Stemme S12 simply the sexiest glider in the sky? We think so here at P1, especially after spending some time up-close with the recently-certified aircraft in Germany.

On 11 March the European Aviation Safety Agency granted type certification for the new Twin Voyager S12 by Stemme AG. This is now being validated by the FAA.

Now pay attention – here’s the history. Stemme GmbH & Co. KG was founded by Dr Reiner Stemme in 1984 in the Berlin district of Wedding. He wanted to create a unique aircraft that combined the properties of motorised propulsion with great gliding characteristics.

The secret’s in the nose – where the Stemme S12 hides its propeller

As an engineer and passionate glider pilot himself, Dr Stemme set himself the target of creating an aircraft capable of long-distance soaring flights at the highest level – independent of towing vehicles, winches and the accompanying crews. His design of a retractable propeller remains unique – connected by a drive shaft to an engine mounted at the aircraft’s centre of gravity allowed his idea to become reality.

By 1986, the prototype of the S10 embarked on its maiden flight and – one year later – was unveiled at the AERO trade show in Friedrichshafen. In 1990, type certification was granted and the first series-production version was duly delivered.

The company moved to its current base in Strausberg, near Berlin, in 1993, and has been producing the S10 every since. However, in April 2015 the new Twin Voyager S12
was launched.

Stemme S12
Soaring in glider mode, the Stemme S12 is a graceful sight

So, what is the S12 all about? Well, that foldable propeller is the big USP. The prop can be housed completely within the propeller dome, with the blades unfolding when deployed. Converting from glide mode to engine mode takes just five seconds.

With an impressive glide ratio of 1:53, combining the engine with gliding means the S12 has a range of 950nm, or 1,759km. It can also cruise at speeds up to 140kts (259kmh) at 10,000 feet.

The solid one-piece canopy offers great panoramic views. The side-by-side alignment is good for sharing workloads, using the same avionics or simply for pure recreation. The cockpit also has autopilot. A separate baggage compartment is integrated into the fuselage, which increases the opportunities for extended touring.

Using the prop and making full use of the 1:53 glide ratio means extended range

The crossover glider certainly proved popular at EBACE out on the static display, with more than passing interest from punters – which is hardly surprising considering the 25-metre wingspan.   There is a retractable undercarriage and two 60-litre fuel tanks, while the wings also fold, and have winglets. The S12 is powered by the ROTAX 914 F2/S1 Turbo engine, while there are also up to eight solar panels.

Personally, we can’t think of a more civilised way of soaring silently through the skies.

The Stemme S12 costs a respectable EU300,000 (US$341,000).