SonexBuilders.net

So, I’ve been looking to try and find any Sonex with a Rotax that’s actually been flying. I’ve had luck on google seeing some, but with few or no information on performance or the install.
My Sonex is very close to being finished, and I have a Rotax installed with the factory mount.
With that being said, every plane I’ve seen exists in countries outside the U.S.
I wanted to know any, and all information anyone might have. And as I’m based in the U.S., I wanted to know if there are even any in the country.
Thanks guys!

I would guess there are few to none in the US. Rotax was not an approved engine in this country due mainly to cost. Sonex didn't offer the Rotax mount until a couple of years ago. The reasons I have read given those who have used the 912 were because their countries would not authorize auto conversions of any kind but those countries recognized Rotax an an aircraft engine and would certify them. Most of the previous Rotax users had to engineer their own engine mounts and fabricate them. One other comment I read in the past was they are so light that weight and balance was an issue that had to be dealt with.
I checked the builder database and only found one entry for the US

I have one flying in Oz,,,, performance is good and weight and balance is fine, but I made my own engine mount simply because of import costs yet moved it 1" forward of the standard aerovee prop position. CofG is slightly aft of my origional turbovee but still well within manufacturer specifications.

I have an almost flying Rotax912ULS in a Onex. I am doing taxi tests which uncovered a couple of problems that I am working on. I have a nose wheel shimmy and the brakes are weak. I have hydraulic toe brakes and I am hoping a couple of hard braking episodes will improve the braking, braking in the brakes as it were. I am going to try balancing beads for the nose wheel.

hi all,
jake is converting his tri gear sonex from aerovee to rotax 912. maybe he can give us an update.
he should be getting close to flying.
and good luck to george. waiting to hear his first flight report!
WaiexN143NM
Michael

Thank you for the replies guys.

Bill, very valid points and makes complete sense. I would just think Rotax installs would be catching on since Sonex offers the mount now. As Jabiru and Rotax are typically the go to manufacturer when you want power and reliability in a light sport aircraft, I would be interested to see the performance contrast between the 2.

Brett, what kind of numbers are you getting? What kind of propeller are you using? Very exciting stuff. Kudos to making your own mount, I can imagine importing would be a pain and far more expensive than making your own. Do you have any pictures available of your install?

George, I imagine that little Onex is going to be a rocket ship. What propeller are you using? 2 or 3 blade? Good luck on further testing! I’m sure you’ll get the bugs worked out and have a fun flying machine.

Michael, I just recently saw his posts. He looks to be doing a great job and I’d love to know his progress.

My Sonex is the Legacy with standard gear. I’m going to be using a tapered tip 62” Warp Drive. I’ll be posting pictures as I go, as of right now my plane is in the paint booth. Fuselage is partially painted and I’m looking to have it wrapped up on Thursday and roll it back in the shop to put all the glass back on and begin painting the wings

Currently in the booth

Hi All
My Rotax powered Sonex has been flying for 2 years now with about 80 hours. Cruise 117Kts IAS at 5200 rpm at 2500 feet, at max weight a little over 1150 lbs climb out from sea level we were seeing 1000 fpm at 70 kts all the way to 7000 feet. I am using a 68 inch wooden GT propeller that comes from a Tecnam 2008 which could be a little coarser. RPM runs to red line at WOT in level flight at 2500 feet. Ref podcast
http://www.sonexflight.com/52/index.html
Cheers.

Well- an explanation for the Rotax absence in Sonex might be that the greatest population of Jabiru is in the US. You also have the option of selecting alternative brands such as Aerovee and other VW-1 aeroderivatives, Corvair, etc. The rest of the world, save Oz of course, seem to favour Rotax: very much so in Europe. This has gone so far that thieves will not steal Jab engines!

What is more; with production of the Jab gen 4 range now in full swing it has become much harder to source main components as cylinders and pistons for the earlier models- and I finally gave up: onwards to Rotax!

For my Sonex A #0525 DS SG, after 550 hrs with Jab which included two top end overhauls, I decided to use the Sonex supplied mount for the 33A engine as a basis for the conversion, and in combination with the ring mount supplied by Rotax. The only components that had to be manufactured were the split radiator setup and two pcs t=12mm flat steel bars, suitably machined and shaped to accept supports and clear engine components, particularily the Rotax starter motor. This will put the Rotax prop flange on the same CL as the Jab, but 35mm further forward compared to the Jab 33A with the shortest prop drive flange on the driveshaft, provided you elect to use the Sonex supplied rubber isolators for the 33A. Lube oil cooling is by a heat exchanger.

Calculations show that the CG will migrate slightly forward compared to the Jab. This is great as I have a 10 gal seat back fuel tank- previously it could only be filled to 75% capacity due to CG issues.

The conversion is well under way now- see the photos. The issues with the cowling are next.

Thanks
Kai

Hi all,
I'm in Oz with Brett but on the east side, I know of two others here flying and another on the way.
My 912 uls powered legacy has been going for nearly 50 hrs. The started kit with not much done I bought was a tri with aerovee. I made the mount to incorporate the rotax ring mount,(supposedly better than a bed mount) and have longer main legs for a larger prop. It's now a tailwheel. The prop flange is about an inch forward and an inch higher than the standard. W & B is good and cruise about 115 kts at 5000 rpm. The Bolly three blade prop I'm using is not optimal as to get 5200 rpm on take off (rotax recommendation) I can over speed in S & L any altitude. But overall happy with the result.
Cheers Peter