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Whatever happened to the Sonex / Rotax??? You know the one that flew at Oshkosh.

Rumer suggested it had engine cooling issues - if true, was this resolved & how?

Sonex factory focus seems to have shifted to the new high wing however if they haven't learnt from the Osh Sonex, it will also have Rotax cooling issues.

I heard through a few people at Oshkosh last year that that plane is owned by the EAA not sonex and it has been pickled and stored. I did hear there were some cooling issues but I don't know the specifics and the plane has flown. I firmly believe with some time and thought the side outlets with dual radiators are a great setup. Mike Arnold used a very similar setup on the record setting AR-5. Given this plane was built in a week for a show that has long come and gone, I suspect the time and effort to work through the cooling issues has not been a priority.

I decided to use a single belly radiator rather than dual because of this plane and my discussions with sonex and Casey at OSH last year. Also, if I need more core area I can have a new one made and swap a belly radiator easier. I don't know enough about the one week wonder plane, but I did look at the layout very carefully when I was laying out m FWF. I think the issue is more about the radiator core area and orientation of the inlet to the radiator rather than it is about this side outlets, but again I don't know enough to confirm.

Skippydiesel wrote:Whatever happened to the Sonex / Rotax??? You know the one that flew at Oshkosh.

Rumer suggested it had engine cooling issues - if true, was this resolved & how?

Sonex factory focus seems to have shifted to the new high wing however if they haven't learned from the Osh Sonex, it will also have Rotax cooling issues.

The HighWing prototype will be using a 130HP UL Power engine. Skip to the 32:25 mark in this video for more information. https://www.sonexaircraft.com/highwing-update-020823/

They had ECU problems that held them up from what Mark said previously. It's too bad that EAA doesn't seem to have any interest in the project. Maybe they should sell it to someone who will get it worked out.

BTW, I don't know what I'd do with all that space in the 2-place cowls.

WaiexB22 wrote:I heard through a few people at Oshkosh last year that that plane is owned by the EAA not sonex and it has been pickled and stored. I did hear there were some cooling issues but I don't know the specifics and the plane has flown. I firmly believe with some time and thought the side outlets with dual radiators are a great setup. Mike Arnold used a very similar setup on the record setting AR-5. Given this plane was built in a week for a show that has long come and gone, I suspect the time and effort to work through the cooling issues has not been a priority.

I decided to use a single belly radiator rather than dual because of this plane and my discussions with sonex and Casey at OSH last year. Also, if I need more core area I can have a new one made and swap a belly radiator easier. I don't know enough about the one week wonder plane, but I did look at the layout very carefully when I was laying out m FWF. I think the issue is more about the radiator core area and orientation of the inlet to the radiator rather than it is about this side outlets, but again I don't know enough to confirm.

2022-02-03-eHotline-www-960jpg.jpg

My Sonex Legacy, custom cowling (much narrower than Sonex), has a single Rotax OM coolant radiator, located lower front of engine, with Rotax OM Extra Large, oil cooler mounted lower aft of engine, in exit air - seems to work.

13brv3 wrote:They had ECU problems that held them up from what Mark said previously. It's too bad that EAA doesn't seem to have any interest in the project. Maybe they should sell it to someone who will get it worked out.

It's not that there is no interest. There is simply not sufficient time to spend on this airplane due to other activities for EAA's flight department. The airplane flew very nicely, and performed great. Yes, there were some cooling issues that were partially solved before the ECU issue cropped up. I flew the airplane quite a bit, and Tom Helm flew it as well. Time just ran out between Sonex and EAA, so the airplane currently resides at EAA with its future to be determined.

There is talk of the airplane going to the Smithsonian to be hung next to the Moni. That would be kind of cool! Stay tuned!!

Hi Joe,

Thats a pity it has not progressed - particularly in the cooling design department.

Rotax cooling, within Sonex cowling/airframe, is an important area that needs to be fully explored - at the moment this is being done by independent minds around the World - far better that a R&D department took it on.

Needs must and it seems that I have managed to get my cooling under control (without any help from Sonex). We are heading into winter, so cooler days sub 20 C occasional morning frost and temperatures at (max 10,000 ft) altitude will start to go into the minus relm. So the real test will be next summer days to 45C + and often + 20C at 5,500 ft.