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Sep 23, 2003
As you can see from my previous posts I'm cheap and I'm into engines. Perhaps I'm on the wrong board cause the replies are pretty slim. In any event here is a link to a radical new engine that may actually come to fruition. It has been more or less quietly worked on for about 20 years now.


I can't get any real numbers yet (can any of you?) but they are funded and are testing a working prototype. My guess is that, like the Mazda, they are going to have seal issues for awhile but that it will be worked out with new materials.

Speaking of Mazda; does anyone have a link to some statistical info on failure rate and causes? I wouldn't think that type of engine would be prone to just quiting in mid-flight for mechanical reasons and would just like to see some real world info.

John Slade

Well-Known Member
Jan 5, 2003
West Palm Beach, FL
Hi, Steve
I haven't looked at the new engine you mention, but I've seen a lot of engine companies get a design, get funding, spend the money and go away. When they fly to OSH, I'll take them a bit more seriously.

As for Mazda stats, you might try the ACRE mail list


I know of four mid flight Mazda engine failures - one was carburation on Tracy Crook's plane early on. He restarted and landed safely. Another recent one was a bolt from the intake injested into the engine. The engine kept running enough for the pilot to make a controlled landing on a road. The bolt had badly damaged the seals and rotor housing. The third and fourth were oil cooler failure causing fire. Both on the same plane, both with the same make of aftermarket oil cooler. I think there may have been others, but I don't know the details.

I havent heard of a catastrophic internal engine failure on a Mazda powered airplane.


Mar 2, 2003
Western Washington
Maybe I'm a bit conservative, but I too would urge folks not to get too excited about any new engine. This is especially the case for companies that claim to "revolutionize" the technology or industry. Yes, there are very promising developments out there and many of them could have great application in our end of the market, but until I see one fly reliably, I'm not going to beat a path to their door.

The vane engine described at the company's web site you provided a link to has actually been around, in one form or another, for over twenty years, possibly longer. I remember seeing a similar development back in college (late seventies, early eighties) and some historical background dating back to the sixties. It looked promising but each time it eventually faded away.

Back then the problems were with the seals (as you guessed), and with temperature and related distortion issues. It is true that material developments could adress some of the shortcomings but only time will tell. If they're just testing the prototype, it most likely will be years before they have anything marketable.

Pesonally, I am a fan of the rotary engine although I have yet to see a good reduction drive that I would be willing to bet my life on. So far, the best approach I've seen is the one from Powersport, although at $6,500 I'm not sure how quickly I would be willing to write them a check. It is however cheaper than what it would cost me to do one right from scratch so maybe it's not such a bad price, especially considering the dollars per rated horsepower.

The work to date by Tracy Crook seems to be very methodical and sound however I have not been following it too closely so I cannot make an accurate evaluation one way or another.

I do however think that the rotary engine is a very promising aircraft application, epsecially considering it has the least amount of failure modes when compared to more conventional powerplants. For more information, I would suggest you call someone like Dennis Hayes at Hayes Rotary Engineering in Bellevue, Wa. Dennis's company has been providing engines to the street and racing industries (and for some airplanes) since the rotary's introduction in the early seventies. While other remanufacturers may ship a few engines per month, Dennis's experience is based on shipping about forty engines per month for the last fifteen years or more. He can also modify the engine for whatever need you may have - many of his design and modification ideas are proprietary and in a few cases, even patented. His prices are also reasonable.

Robert Young

Nov 24, 2003
Apple Valley, CA
engine concepts

Orion makes a good point. The only new engine concept , other than turbine, that was made into a viable commercial product during the whole of the 20th century is the Wankel rotary. There have been hundreds of schemes in the past hundred years and so far the reciprocating piston is still king. There must be something to be said for the manufacture of round holes. Forty years ago I worked in an engine lab for a very good engine company, McCulloch Motors, and that company explored all kinds of schemes. Still the simple piston is on top.

There is a real need for a good redrive and if that can come about we have so many good engine choices we cannot live long enough to benefit from all of them.

Several car companies are now using a continuously variable transmission CVT in their cars and we know they must be efficient. The Toyota Prius is one of them and there is one in a Honda Civic. Both theses cars are pushing for max efficiency so I have conluded the CVT must be so. These things use metallic belt systems that push as well as pull. I have not seen one in parts but only in texts.