by Philip Greenspun

Site Home : Flying : One Article

Airplanes.  Deutsches Museum. Soaring can be more fun than flying a powered airplane. Soaring is silent. Soaring is not something that you do in order to get from City A to City B. You don't soar if it is dark (no thermals). You don't soar if the weather is bad (no fun). Traditional sailplanes are problematic, however, in that they have no engine. You need to be towed up by a little Cessna or Piper. Towing presents its own hazards and the need for a tow means that you can only soar on weekends when the local soaring club is operating. You have to wait your turn for the glider and then for the tow plane. If you live in a place like eastern Massachusetts the first thing you'll do when you release from tow is sink back down to the ground. We have no mountains. In the winter months (all 9 of them), we have no rising hot air from Walmart parking lots.

What would be really nice is an airplane that is reasonably high performance as a powered plane so that you could get to the mountains within an hour or so. Then you want to be able to shut down the engine and have efficient soaring performance for staying aloft during the middle of the day on ridge updrafts. As the sun begins to move toward the horizon, you want to crank up the engine again and head back home. This is what the Stemme S-10 VT, described at, does. It cruises at 140 knots, making it nearly as fast as a comparable priced ($200,000 and change) standard single-engine plane. It soars with a glide ratio of 50:1 and a 112 feet per minute sink rate, which is comparable to the very best and most modern glider designs. The only real drawback to the Stemme is that it holds just two people and no dogs.

One fly in the ointment: the NTSB Web site reports the following:

On July 14, 2001, at 1300 central daylight time, a Stemme S10-VT motor-glider, N502SC, was destroyed by fire after an emergency landing at the Langlade County Airport (AIG), Antigo, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 CFR Part 91 and was not on a flight plan. The pilot and one passenger were not injured. The local flight departed from AIG at 1255.

The pilot reported that approximately one mile after takeoff at 1000 feet above ground level he heard a loud pop and had smoke in the cockpit. An emergency landing was conducted to AIG where the pilot and passenger evacuated the aircraft.


According to the Stemme USA sales people, the NTSB investigation into this accident was apparently "inconclusive" due to the fact that firefighting equipment did not arrive on the scene in a timely manner. Therefore the plane became so badly damaged that it was tough to tell anything more than that there had been an engine fire. Very likely the problem was a manufacturing defect in the 15-hour-old Rotax engine. There have been fires in Rotax-powered ultralights when the carburetor separated from the engine. An alternative explanation comes from an airplane engineer: (1) a lot of times the Rotax engines are installed with an air filter stuck onto the carburetor, (2) the carburetor is mounted to the engine with rubber, (3) this means that there is a fair amount of mass vibrating freely supported only by the rubber carburetor mounts, which weren't really designed to handle more than the carburetor, (4) Rotax-powered airplanes such as the original Diamond Katana that have a separate airframe-mounted air intake system have never had a carburetor separation problem.

The FAA lists the owner of the burned-up Stemme as Cornew Stuart of Winnetka, Illinois. Stemme USA says that the pilot has already taken delivery of a replacement and indeed the records show that the "512 Horses" corporation in Winnetka registered a new S-10 VT in December 2001.

The factory only builds 18 per year. Owners seem to be very happy with the planes but there are also a lot of reports of problems during the first six months. It might be better to find a low-hours second-hand Stemme, especially given that the factory is in Germany.

The only place in the United States that seems to rent or train in the Stemme is, near San Diego.

A Simpler Cheaper Alternative

An alternative to the Stemme is the Diamond Katana Extreme (HK36) motorglider. This airplane is substantially simpler than the Stemme, owing to the fact that the prop is non-retractable. The Diamond glider is about half the price of the Stemme. The Diamond glider is available with standard non-retractable tricycle (nosewheel) landing gear--virtually all competitors are tailwheel airplanes. Basically the Katana Extreme is a Diamond Katana trainer with longer wings. Any monkey ought to be able to fly it. Any mechanic ought to be able to maintain it.

The Diamond has a much higher useful load and more cargo space than the Stemme. The Diamond does not have a reputation as being a high-maintenance animal.

Why would anyone buy the Stemme instead of the Diamond? The Diamond sinks roughly twice as fast and glides only about half as far per unit of altitude. As a glider, the Diamond is only about as high performance as the better trainers used by soaring clubs (though these of course lack motors).

Katana Extreme owners seem fairly happy with their machines though at least one that I talked to had upgraded to a Stemme and did not regret it despite the extra maintenance hassles. For an inexperienced pilot such as myself the tricycle gear alone may make the Katana Extreme a natural purchase. Coupled with the fact that I did my training in a Katana DA20 and that I purchased a Diamond DA40 (four-seat Katana, essentially), the Katana Extreme might well be the best starter motor glider for me.

For training in the Katana Extreme, contact Russ Hustead ( in sunny Arizona; sadly this is an older tailwheel version of the plane but Russ himself comes highly recommended as an instructor) or A&M Aviation at Clow International Airport, Bolingbrook, Illinois,, which flies the tricycle-gear version.


Text and photos (if any) Copyright 2002 Philip Greenspun.

Reader's Comments

There are a couple of other motorgliders out there worth considering, although none I'm aware of with the engine on AND engine off performance ot the Stemme.

There is actually a bit of a tradition of european touring motorgliders, exemplified by the designs of Rene Fournier. The RF-4, powered by a Limbach VW conversion, was at one time fairly numerous both here in the US and in Europe. Mira Slovak, a famed aerobatic pilot, used to deliver them from France by flying them across the Atlantic! The EURAVIAL RF-47 appears to be a continuation of this line.

I thing Diamond still makes the long-winged motorglider version of the Katana.

And the venerable, all aluminum Czech Blanik is available in a powered version.

And some of the high-zoot glass sailplanes are available in "self-launching" versions, with small two strokes and climb props that retract once they've gotten you in the air.

Web search engines on these keywords should get you fresh links if you're interested.

-- Ryan Young, January 16, 2002

Your big hairy white dog will be just the thing to keep you warm at altitude, just make sure he can keep very very still and has his own O2! ;^) My trainer was the Krosno KR-2 Puchatek, and was fortunate to have Gary Speight as my instructor.

Safe flights, Hernan

-- Hernan Mapua, January 21, 2002

I've never flown a plane, but I did get to go soaring in a Grob on Oahu, Hawaii. Highly recommended.

Also, one of my best friends from college owns a Christen Eagle, which, if you ever get the chance to fly in one, (or a Pitts, or any aerobatic biplane with a competition-class pilot) it is a life-changing experience.

-- Gen Kanai, January 23, 2002

Although I appreciate the utility of a motorglider, I'd like to suggest that it misses half the point; the element of risk involved while searching out lift in a true sailplane is what makes the game. Those moments spent near the ground, hunting weak lift from any source available; thermal, ridge, shear... suddenly rewarded with just enough gain to bring the ship back to an altitude high enough that I can again gamble on my direction....those moments are acid-etched; they are real. Later, catching a strong thermal, I am elated, truly transported by the achievement. I'm not convinced my feeling would be as deep had I a convenient Rotax aboard. Well, to each his own; see you at 10,000 feet!

-- Jim Hultman, February 14, 2002
The March 2002 issue of AOPA Pilot has an article on the Stemme (there's also a review of the other plane Philip's interested in, the DA40). The author flew with Steamboat Soaring Adventures in Steamboat Springs, CO (

Philip, if you don't have a copy, someone at your flight school will (I'll let you read mine if you give me a ride in the DA40!)

-- Greg Ames, March 4, 2002
I have written an online gliding simulator. Flight Club is open source and may be of interest to nerds as well as pilots. See you at cloud base. :)

-- Dan Burton, June 5, 2002
As a soaring pilot I highly recommend getting your soaring rating.

There are a couple of places that I would recommend in New York State. The first is Knauf's place, Ridge Soaring (now Keystone), and the Harris Hill Soaring club. Both are big, year round operations, soaring knows no season.

Now if you want to take a couple of weeks (or a month off) come down to Florida to Seminole Lake Glider Port (, we also fly all year long, and are the biggest commerical operation on the East coast.

Also one motor glider that I would recommend is the DG series of sail planes, excellent sail planes that are self-launching.

But don't force yourself into a motor glider.

Also join the SSA, and use thier website to find the soaring sites near you.

-- Shawn Clark, June 7, 2002

I've never flown a Stemme or the Diamond Xtreme, so I don't want to knock either aircraft. However, IMHO most people would be better served by bypassing them and flying conventional (powerless) single-seat gliders. A motorglider has the undoubted convenience of self-launching, but beyond that it hasn't got much going for it: it's simply neither fish nor fowl, plus far too expensive.

BTW, may I add that all too many pilots get caught up in the 'ghettos' of power flying vs. soaring; it's common to hear people sneering away when they have only tried one sort of flying and have little or no experience of the other. Personally I enjoy both, they each have their pros and cons.

-- Roger Harris, June 24, 2002

Add a comment | Add a link