SonexBuilders.net

Hi! Happy New Year to everybody!

I have a question, I do not understand why Sonex is not supporting the use of a Rotax (912 or 912S) on its planes.
In Europe, most people will not buy an ultralight (ULM) with either a Jabiru or an Aerovee.
Last year I wanted to buy a Sonex kit and I registered to the formation course in Oskhosh but, because Sonex refused to give me any indication as for the use of a Rotax (fixation... balance...), I cancelled my project.
A friend of mine has built a Sonex with an Aerovee last year... and after 25 hours of flight he has had problem with the (4) cylinders, discarded the Aerovee and installed an used Rotax engine.
I have tried to get more explanation from the Sonex technical team but they keep saying that the Rotax is too much complicated for their planes????
I do not understand their position because I can assure you that Sonex would sell ++ more kits in Europe if only they were proposing (beside Jabiru and Aerovee) a Rotax engine!
?!?!?!

The story I've heard is that Sonex wants to stay away from liquid cooled engines to simplify building and operating their airplanes. I've also heard its because the Rotax 912S is too expensive and/or too heavy for use.

I do know several people have successfully grafted a Rotax onto a Sonex airframe so it can be done, but just like you pointed out the factory probably won't provide much support for that engine. I understand your concerns and wish I could help on this one...

Good luck.

The only thing I can suggest is that you keep asking sonex if or when they will offer a rotax option and ask everyone else you know who wants a rotax option to do the same. There have been many things that Sonex has said in the past they will never do or offer but with enough pressure from builders they have changed their mind. The hydraulic brakes they are now offering is one of the latest examples of this. They have maintained for years that there is nothing wrong with the mechanical brakes and that adding hydrauilc brakes to a sonex would just add unneeded weight and complexity. Enough builders are now doing it on their own that Sonex has finally seen the light and will be offering their own version. If there was enough interest in a Rotax installation I am sure that at some point they would develop one and start offering mounts, cowlings, and other fwf components to support it. I think what they are looking at right now is the larger Rotax engines will work for the airframe but the cost for one in the states is way above the aerovee and pretty close to the Jabiru for the same performance. If they are less expensive in europe maybe that needs to be brought to their attention. I would expect a "sorry but, no" response but you might get some wheels turning behind the scene.

Keith
#554

Here's what Sonex has to say about the Rotax engines on their website FAQ page:

This engine certainly could work for the Sonex, but the use of reduction drives and radiators runs counter to our "keep it simple" philosophy. It also just doesn't make economic sense. You can install a clean and simple 120 hp 3300 Jabiru Engine for less than what it costs for either a Rotax 912S or 914.

http://www.sonexaircraft.com/choosing/s ... html#rotax

rizzz wrote:Here's what Sonex has to say about the Rotax engines on their website FAQ page:

This engine certainly could work for the Sonex, but the use of reduction drives and radiators runs counter to our "keep it simple" philosophy. It also just doesn't make economic sense. You can install a clean and simple 120 hp 3300 Jabiru Engine for less than what it costs for either a Rotax 912S or 914.

http://www.sonexaircraft.com/choosing/s ... html#rotax

Thank you, I know their "explanation". However, in Europe if you want to build an ultralight (i.e., ULM) and fly without all the problems (cost, maintenance, paperwork...) associated with the "real" planes, the empty weight is about 300 kg max AND you cannot use an engine of more than 100 HP.
On the other hand, at least in Europe, Jabiru engines are almost as expensive than Rotax engines AND their reputation is very very bad! Almost nobody buys now an ultralight (ULM) with a Jabiru and nobody wants to get an used one!

Therefore, I think that even considering only the Sonex business (number of their sales) they should propose also the Rotax... the plane is good and they could sell a lot of kits in Europe!

Regards

kmacht wrote:The hydraulic brakes they are now offering is one of the latest examples of this.

I must have missed that.. which Hydraulic brakes are they selling? (can't find it on the website)

They also did the same thing with wingtip lights.

They just announced the brakes on the Yahoo lists. A snippet:

"This new disc brake system will be announced and detailed in the next few weeks... Stay tuned to our web site for a comprehensive announcement with images and pricing coming in the next few weeks. No further will be available from Sonex Staff until this posting is made."

My impression is that their install will use a single master cylinder plumbed to both brakes and driven by the same brake handle used for the cable design. As of now, I plan to use their brake units (disc, pads, wheel, etc.) with independent toe brakes.

I'm pretty sure the fact that Sonex now has hydraulic brakes on offer has everything to do with this project:
http://www.sonexaircraft.com/research/u ... 13012.html

I remember someone on the sonexgroups mentioned he had talked to John Monett about the SubSonex and he said it needed hydraulic brakes, so it's only logical that they designed the brakes to fit all Sonex models and not just the SubSonex given there is such a high demand for them.

Hi
I run an aerovee in my tail dragger sonex for a few years now and have to ask have any of the people installing toe brakes have ever trie :) d out the standard brakes that are supplied with them I will admit in advance that the drums leave a lot to be desired in the fact that if you dont get the drums that have been machined they can shake the living clappers out of you.But they work sufficiently well enough to pick the tail wheel back up on landing if you haul on them too hard and they will hold you at full throttle on run up , as for having differential brakes there just seems to be no need on either the nose wheel or the tail dragger as the rudder has a really good authority well under stall speed and once the tail wheel is on or the nose wheel is down these things will turn on the proverbial dime.
I am not trying to tell people what to do just letting you know from one that has been there and trying to help people make a well informed decision on facts.
Regards Bish

Hi
I would love to hear some flight reports on the rotax powered sonex, is there any chance at all that you could get your hands on some flight performance data for me as I am really interested in the concept and just happen to have a 912s sitting in the corner of my shed . problem is that I cannot find any performance figures appart from the one from norway that runs a turbo and is injected and runs a constant speed prop .
Regards Bish