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Dr. Reiner Stemme - Background

Stemme 25 Years

Stemme Newsletter S10-VT Special

Dimensions and Performance

side-by-side Cockpit

Drive Shaft - Propeller - Mid-Fuselage-Engine

Landing Gear

Wing folding mechanism

Navigation with LX-8000 / 9000

Oxygen System MH EDS Modell O2D2

SPOT Satellite Messenger

All-weather Covers - Hail Protection

Aeroprotect lite - Cockpit Cover for a journey

Cobra Trailer

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STEMME's most remarkable innovation is the patented propulsion design, consisting of a certified four-stroke aircraft engine mounted behind the cockpit, driving a nose-mounted propeller via a lightweight carbon fiber drive shaft. This light and cost effective drive shaft was brought to market in the early 1990s and enabled STEMME to position the engine in the middle of the airframe near the center of gravity with almost no cost or weight penalty.

No other powered sailplane design has combined the high performance of a sailplane with the practicality and convenience of a power plane. As a result, soaring was finally freed from local airfields and the requirement for ground handling support, creating a new class of gliders. Starting from convenient local airfields in the morning, owners fly under power to optimal soaring conditions anywhere within several hundred miles, soar all day, and still have time to return home the same day. The STEMME propulsion design makes high performance cross country soaring a convenient form of recreational, competition and record-setting flight.

The mid-engine layout offers numerous advantages. The pilot may transition between powered and soaring flight in seconds without moving any portion of the drive train. After shutdown, the engine remains safely out of the flow of cold slip-stream air, so there is no sudden thermal shock. The frontal drag is minimized yielding excellent handling qualities and optimized aerodynamics, resulting in high cruising speed and low fuel consumption.

For ultimate soaring performance and a glide ratio of 50:1, the S 10 is equipped with the STEMME-RETRAC-PROP completely concealing the folding propeller inside the movable nose cone. Cooling air is drawn in from the lower front and exhausted up and rearward. This method of cooling is also environmentally friendly due to reduced noise emissions on the ground.
As of today, more than 200 aircraft are operated throughout the world. While most are quietly enabling their owners to experience the shear joy of cross country soaring, others are using the aircraft to break longstanding records. Late in 2000, for example, Mr. Klaus Ohlmann set an astounding FAI-certified world record of 2.463 km (1,330 NM) in the category “longest distance’ in soaring flight using a STEMME S10VT.

The overall conclusion: The clear benefits of the STEMME mid-fuselage-engine layout are proven. Owners enjoy a host of advantages including improved performance, decreased fuel consumption and minimal noise levels.

Folding Propeller in the Retracting Nose-Cone

Rotax 914 efficiency

Martin Hellmann recently had a discussion with a colleague in the Aero & Astro Department here at Stanford and the question of Otto cycle efficiency came up. As part of that exchange, I calculated the efficiency of our Rotax 914 engines at maximum continuous power and found it to be approximately 29%. That is surprisingly high and if anyone wants them, here are the numbers. The page numbers refer to the newer version of the 914 Operator Manual.

Energy content of gasoline is 34 MJ/liter

According to page 8-2 of the Rotax Operator Manual, fuel consumption at maximum continuous power is
27.2 liters/hour (7.2 US gallons/hour).

That corresponds to a raw energy input of
34 MJ/liter x 27.2 liters/hour = 925 MJ/hour.

According to page 10-3 of the manual, maximum continuous power is
73.5 kW = 73.5 kJ/sec = 73.5 kJ/sec x 3600 sec/hour = 265 MJ/hour of output power.

The efficiency at that operating point is therefore 265/925 = 29%.