SonexBuilders.net

Skippydiesel wrote:- if asked outright (as happened) I give a truthful answer.

Yes sir ... I do tell the truth. With my Challenger I was never asked what it was for. With my current plane ... well the spinner isn't chrome:

https://www.youtube.com/watch?v=Hg0fgs4cFuE

Skippydiesel wrote:Problemo! -

The few installations I have seen with the double/forward coolant radiators, have been aftermarket fuel injected 912 variants - mechanical fuel pump is redundant/deleted.

I will not be removing my fuel pump any time soon - this pretty much makes what I saw as being quite a straightforward installation way more complicated on the right side of the gearbox. - Such is life & homebuilt aircraft!

Sure- you´ve got a point!
I keep forgetting that not everybody flies efi these days. The factory dual carb setup is happy with a mech fuel pump, which is sitting where the right rad would go. This will indeed require additional effort to find a place for the Rotax std rad. But it has been done- have you seen the Sonex installation?

Then again, some of us are more inclined to find solutions than others. See below: an Onex with a BMW engine! And that coolant radiator…..

WOWEEEEE!

For supply of small radiators in Australia, how about heater core units from a small car? They should be pretty cheap from wreckers. I don't know if any are a suitable size but it's worth looking. My guess is that you would also need to make a small reservoir/header tank.

That BMW Onex is seriously unique. I'd love to see pictures of the cowl. That radiator is so large that I wonder if they even have a scoop for it, or if it just forces under cowl air through it.

When I was working on rotary engine installations, I was really tempted to try an oil to water exchanger rather than a typical air oil cooler. I'd bet it would be heavier, but it allows one larger radiator, rather than separate air and oil radiators. In some cases, that might help with packaging.

The Aerosport A 240 and A 220 uses the small double radiators located in the front of the cowl. Small space lots of hoses very efficient.
I'm mounting my Rotax radiator in an opening in the bottom cowl under the gear box in my 0nex, long hose runs. We will see.
I had A Murphy Renegade Biplane with an auto radiator mounted on top of the engine, worked well, lots of plumbing, large cowl opening,
Lots of drag, speed not an issue.
Tom Ryan. 0nex 74

peter anson wrote:For supply of small radiators in Australia, how about heater core units from a small car? They should be pretty cheap from wreckers. I don't know if any are a suitable size but it's worth looking. My guess is that you would also need to make a small reservoir/header tank.

Good call!
Back in the days when we were still doing Buick V8 installations, quite a lot of installers got hold of a set of heater cores, and/or car ac evaporator cores. They still seem fairly popularitet among auto engine gurus. And indeed a header tank/swirl pot is also needed.

I have been reading all the posts about cooling issues (liquid) on Sonex Aircraft. If I may add my two cents. I believe the people having issues are with Rotax engines. I am building a Waiex Legacy with Jabiru 3300 with Liquid cooled heads. So I too have looked at where to put the Radiator. I opted for the back for now. Anyway for those looking for solutions I just want to add to look at Jabirus with LCH for another variation.

I have been reading all the posts about cooling issues (liquid) on Sonex Aircraft. If I may add my two cents. I believe the people having issues are with Rotax engines. I am building a Waiex Legacy with Jabiru 3300 with Liquid cooled heads. So I too have looked at where to put the Radiator. I opted for the back for now. Anyway for those looking for solutions I just want to add to look at Jabirus with LCH for another variation.

Nick

Nick wrote:I have been reading all the posts about cooling issues (liquid) on Sonex Aircraft. If I may add my two cents. I believe the people having issues are with Rotax engines. I am building a Waiex Legacy with Jabiru 3300 with Liquid cooled heads. So I too have looked at where to put the Radiator. I opted for the back for now. Anyway for those looking for solutions I just want to add to look at Jabirus with LCH for another variation.

Hi Nick,

The problem is not the Rotax engine as such but the lack of experience in fitting/adapting them (& attendant cooling requirements) to the Sonex airframe. This will be resolved, as a matter of course, as more builders fit the class leader in this HP range.

It should not matter where you put your heat exchange units (Radiator/coolant, Oil cooler, Barrel fins) as long as they have a reliable pressure (high to low) differential acting on them ie there must be a significant air flow over/through the heat exchanger.

Mounting a radiator behind the engine can work BUT predicting the pressure gradient (& direction) in this area can be problematic due to the complexity/turbulence of the under cowl air flow.