SonexBuilders.net

I, too, feel a tinge of excitement with this announcement. Not that my Jab3300 has ever given me cause for concern in over 500 hours (well maybe a little). But, in my opinion, the "quality" of the engine choices for the Sonex have never risen to the "quality" of the airframe and the 912 alternative may just change all that.

Is anyone considering the 912iS so as to get past the dual carb matter? Yes, it's a few thou more but who's counting dollars when all other costs are added together when making this change. Making this mod to my Sonex would result in spending almost as much money as I've already got wrapped up in it to date, including the 3300!

Just dreamin',

Art,,,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,,,,Jab3300 #261

Hi all,
Yes would be great if sonex retro fitted a plane in their fleet to a rotax 912. Then offer a complete fwf package , more than just the ( legacy or b) mount. Your correct jake and art , people looking for reliability. We are happy with our jab3300. How many out there thinking of converting to the rotax912? It seems to be the gold standard engine for lsa. This is long overdue!, thanks sonex for listening!

WaiexN143NM
Michael

Hi Jake,

Good luck with your Rotax installation. I can understand the desire to move beyond the AeroVee and go with a smooth, reliable, modern powerplant.

Nice of Sonex to offer the Rotax mount for the "legacy" fleet. That is a good start but more effort and support is needed to make this a workable option for a broader population of Sonex builders.

It would be really nice if Sonex actually installed a Rotax on a Sonex or Waiex, did some actual flight testing of this configuration and then developed and offered to Sonex builders a quality "firewall forward" kit for the Rotax installation.

What I can tell you from personal experience is that re-engining an airplane isn't always as easy as you might imagine.

Keep us posted on your progress.

Don Bowen
Viking Waiex N49YX
www.mykitlog.com/donbowen

Generally I support the 'go to Rotax' thoughts in this thread, but offer a small caveat - your mileage may differ.

I've flown a dozen or so Rotax engined aircraft, and have found them to be smooth and powerful, mostly. I have had serious problems however with a couple of them, one new under flight test, the other at nearly 900 hours during the builder's checkout on type.

In both cases the engine started cutting in and out at full throttle, resulting in 4 forced landings, all back onto the departure runway.

Fuel supply and/or the complications of the dual pressurised carbs seem to be the root of the problems. Very careful attention to installation, fuel flow, and general set up seems to be required, more so than for instance in the Jabiru installations I've been involved with.

I understand the US military buy Rotaxs for UAV installation, but on delivery remove the stock carb set up, and replace with some other, unknown to me, carburation. On the plus side these new carb pairs are sold off cheap on eBay!

I'll be sticking with my as yet unflown AeroVee, much more affordable and about as simple and straightforward as you can get.

Have a great Oshkosh, I'll be jealously thinking of you this side of the Atlantic.

Actually the problem with the 912 isn't really too bad. They have had issues with fuel pump over pressuring the carburetor and causing the flouts to close and stay closed tell pressure is gone; engine starting to die then pump works again unless you have backup electric running . The fix is pretty simple I had DAR explain this to me. I guess rotax has now resolved the problem with a fuel return. I was one of the people that wanted to put rotax on my sonex and once I was told the factory wasn't going to build a mount for my legacy sonex and the guys in the U.K. Didn't return my email I decided to go with 3300. I was really bummed because I had just bought the new engine when I found out they are making mount. The rotax is a proven engine and pretty simple to install. The UAVs the government used rotax engines on were converted to fuel injection. I have a friend that owns one with a few hundred hours on it. People need not be afraid of the rotax jabiru or even auto conversions. They have all had problems and the manufacturers are all ways trying to improve.
Mike

I just received my Sonex model A legacy Rotax 912 engine mount. It is a tri gear mount. I have inspected it and it looks great. This is the new mount from Sonex. The mount appears to be heavy duty. I like it. Here is a picture:

Jake

I am waiting for mine. What I like about this one verses 3300 is that the nose gear is centered.
Have you ordered your motor ?
Ben

Jake,

Any chance you have a website tracking the Rotax install, especially any lessons learned along the way?

Mike