Posted: 11/3/2009 21:12:09
Would love to hear from anyone who has used or toyed with the idea of using a Wankel on an ultralight. I have a Sachs Wankel KM24 out of a snow mobile that I am entertaining thoughts about. Stripped down to the essentials, It weighs 45 lbs, and is rated at 23hp turning 6000rpms. It seems to be in roughly the same ballpark as the Rotax 277.
The mechanics I have talked to say one of the strong points about Wankels in airplanes is they don't usually freeze up if things go wrong, as the alu case will expand more than the iron rotor if they overheat. They just run more poorly.
I've read about some home builders using Mazda Wankels, but there seems to be very little happening in the ultralight field with them. Any experiences, thoughts, or even rumors you might have would be welcome.
Posted: 11/3/2009 22:01:36
There was a Revolution rotary at Oshkosh fitted to an Msquared ultralight - - http://www.revrotaryinc.com/aviation.html
The rotary that's been causing a big stir is the karting engine the Aixro XR50 which claims 48hp from 32lbs. I know it's been used on an ultralight gyro and on some paramotors / PPCs. It powered the paramotor that flew over Mount Everest
Posted: 11/4/2009 10:10:59
The Revolution rotary sounds promising, but I don't hear a lot happening with it other than Msquared, and a couple years ago Phantom Ultralights was promoting the XR50.. It all sounded very good for a while, then they had oil seal problems, and it just disappeared. My last emails to them went unanswered.
On of the things I like about the Sachs Wankels is the air cooling and lube through the fuel mix, much simpler than radiators and oil systems. However, the cooling fins do make for a more bulky engine.
The supercharger for the XR50 used on the Everest paramotor is interesting, the utter simplicity of the the basic wankel is very appealing to me though.
Posted: 11/4/2009 10:35:29
The X50 engine that Phantom was working with could not get through the necessary hours. Eric (?) had problems with bearings. The thrust loads destroyed them. He was looking at remachining the cases for a more appropriate bearing set and basically ran out of energy/money. Still a viable option with the right funding and testing.
All the attempts at using rotary engines have run into the same problems $$$$ to do the development and get production going to bring the price down. It takes very deep pockets to cover the years and millions to sell a product. Maybe we will see the US gov. in their RPV development fund the production set up that may trickle down to us. Contact Magazine did a great work up for an engine company a while back - very promising not only for aviation but other utility applications but fell on the $$$ hard times.
Posted: 11/4/2009 22:07:05
I had never heard of the Aixro XR50 before last night. I couldn't find a lot of info on it but it is a go kart engine that weighs 32 lbs and puts out 48 hp somewhere around 7000rpm. Since it will need something like a 3:1 speed reduction to turn a prop anyway, I wonder how it would be to build a strong space frame to house the PSRU (belt) with the engine mounted inside the frame and the thrust bearing on the driven shaft behind the propeller hub. The entire assembly could be shock mounted to the airframe with a bed style engine mount.
Posted: 11/5/2009 10:49:21
Give Erik a call at Phantom...http://www.phantomaero.com/
He will give you a story.
Posted: 11/11/2009 22:50:52
I spent quite some time researching rotary engines for U/Ls. Revolution Rotary Engines (RRE), and a couple other companies have tried unsuccessfully to convert Aixro based engines for aircraft. Rotary engines have a harmonic resonance issue that tends to overload and break major components, like main bearings and crankshafts.
It's not an unsolvable problem. But you can't just bolt your favorite reduction drive and prop to the engine and expect it to be reliable. Parajet is selling a small rotary engine option for their backpack PPGs, that is Aixro based. Rotary engines also tend to get poor fuel economy without a complex fuel injection system.
I got all the info about RRE's engines, and wasn't impressed. They had a few that looked cobbled together and were heavy, high priced, with no warranty. RRE is working on developing their own engines in different sizes. It didn't sound like any would be well suited to U/Ls.
Posted: 11/12/2009 10:55:58
RRE seems to have disappeared - emails and phone calls go unanswered both from me and a kit builder in Canada. As I mentioned in an earlier post it takes deep pockets to stick out the development costs.
Posted: 2/20/2010 23:22:00
I realize this is an old post and my no longer be of much interest so will be brief. I just attended Mo's 7th Annual Flying Circus and there were two groups there with the Wakel engines. One was an individual with the KM24 and he was pleased with it. The other was the Parjet Paramotor people who are semi local to me and I intend to do more followup on that application for fixed wing. Let me know if you are still interested and want more info.
Grant Smith CFI
Posted: 2/22/2010 15:04:33
Yes, I would be interested in hearing what you find out. It does seem it would be good for fixed wing aircraft.
Posted: 1/20/2011 18:08:28
I just signed up on your web site today. My friend and I are loking for an engine around 40 Hp that we could use in our latest brain storm. We are looking for people to contact about small engines that can fly vertical or horizontal. We would like to contact someone that handles the Fuji , Rotax etc. engins
Posted: 3/3/2011 16:29:59
We're building a project (www.e-Go.me) around the Parajet Rotron wankel (http://www.parajet.com/index.php?id=28) which is about 22.8Kg installed, and delivers 40HP. They're in quantity production, and seem to have good reliability and TBO.
Fuel consumption is between 2 stroke and 4 stroke. Noise is low and vibration almost imperceptable.