Radiator placement - help needed please!

[Marty_d]

Hey folks,

 

Looking for some advice on the placement of my radiator.

 

It seems like the cowl I've made possibly could have used a bit more room at the front end.  The cowl slopes backwards which I guess may be more aerodynamic but doesn't leave much room in front of the engine and especially the exhaust pipes from the front 2 cylinders.

 

It looks like I have 3 choices:

 

1. Mount the radiator at an angle to the starboard side of centre so the port outlet (upper) is between the oil filter and the exhaust tubing:

 

2. Mount the radiator at an angle to the port side of centre so the port outlet is outboard of the exhaust tubing:

 

3. Redesign the entire front of the cowling so it's squarer, protrudes out at the front more to allow the radiator to sit more vertically.

 

I really don't want to do option 3 because (a) I'm sick of fibreglassing and (b) I'm out of carbon fibre, but that depends on clearances, tolerances and allowable angles for radiators. 

Is there any advice on how far hoses should be from exhaust outlets, how far radiator tanks should be from the cowling, and what angles radiators can be mounted at?

 

Thank you!

 

Cheers, Marty

[IBob]

Marty, my coolant radiator hoses pass quite close to the exhausts.
I made little aluminium heat shields, which stand off maybe 6mm from the hoses, allowing air to pass both sides, to block and dissipate radiant heat. They are held in place by the hose clips. Seems to work......

 

[skippydiesel]

IBob - veeery nice!

 

may need your help in the near future to redesign/placement my Sonex cooling system.

Edited May 13, 2023 by skippydiesel

[skippydiesel]

Marty_d,

 

I will be wrestling with a very similar problem,in the next month or so, when I will be returning my Sonex/Rotax 912ULS to the workshop to completely redesign its cooling system.

 

Have you considered a sloped back, vertical (longitudinal?) placement between the exhaust  pipes? The radiator does care what plane its in,  just that the air flow passing through it, is from high to low pressure & is sufficient to carry enough heat away.

[IBob]

Skippy, I didn't design it. I just followed the instructions, though the al. heat shields were my own add-on.

Note, though, the SS corrugated tube supplied, which allows the plumbing to be formed into tight swept bends, makes for a compact result. Makes some folks nervous, but I think it an excellent innovation. The one on the LH side goes round the engine rear and up to the back of the coolant header, and you form it in place.
 

[onetrack]

Gee Marty, now you've stuffed up the design to stop you from fitting the radiator, the solution's obvious! - you're going to have to swap the Rotax for an air-cooled engine! 

[Old Koreelah]

Marty the solution is obvious: up front is too plurry crowded, so put it where there’s mobs of unused space:

 

[Marty_d]

Well I would, OK, but imagine the weight of the extra water and hose...

[Marty_d]

5 hours ago, IBob said:

Skippy, I didn't design it. I just followed the instructions, though the al. heat shields were my own add-on.

Note, though, the SS corrugated tube supplied, which allows the plumbing to be formed into tight swept bends, makes for a compact result. Makes some folks nervous, but I think it an excellent innovation. The one on the LH side goes round the engine rear and up to the back of the coolant header, and you form it in place.
 

That's not a bad idea Bob - move it back a bit under the exhausts and put the oil cooler up front.   Thanks!

[skippydiesel]

11 hours ago, Old Koreelah said:

Marty the solution is obvious: up front is too plurry crowded, so put it where there’s mobs of unused space:

 

 

Its almost the Mustang concept,  that isn't working for my Sonex - hence the return to the workshop for a redesign/fit.

 

The new and improved(??) concept, is to have the coolant radiator at the front (innovative?) - still working on the oil cooler location.

[440032]

My two cents, and how I tackled oil cooler placement on something else - but same basic problem to solve.

Mount the cooler to what points are available on the engine. This is the very first thing that needs to be considered I think. There's no point trying to stuff it in the cowl if there's nowhere to mount it to.

 

Modify the cowl to suit.

[Old Koreelah]

Who says the “radiator” has to be rectangular? A home-made exchanger could be made to fit the available space.

[Blueadventures]

19 hours ago, Marty_d said:

Hey folks,

 

Looking for some advice on the placement of my radiator.

 

It seems like the cowl I've made possibly could have used a bit more room at the front end.  The cowl slopes backwards which I guess may be more aerodynamic but doesn't leave much room in front of the engine and especially the exhaust pipes from the front 2 cylinders.

 

It looks like I have 3 choices:

 

1. Mount the radiator at an angle to the starboard side of centre so the port outlet (upper) is between the oil filter and the exhaust tubing:

 

2. Mount the radiator at an angle to the port side of centre so the port outlet is outboard of the exhaust tubing:

 

3. Redesign the entire front of the cowling so it's squarer, protrudes out at the front more to allow the radiator to sit more vertically.

 

I really don't want to do option 3 because (a) I'm sick of fibreglassing and (b) I'm out of carbon fibre, but that depends on clearances, tolerances and allowable angles for radiators. 

Is there any advice on how far hoses should be from exhaust outlets, how far radiator tanks should be from the cowling, and what angles radiators can be mounted at?

 

Thank you!

 

Cheers, Marty

Usual locations are oil cooler under gearbox / propeller flange and radiator lower.  Where is your oil cooler located?   Some place oil cooler low on fire wall with a portion into the breeze just outside lower cowl profile; such may allow lowering your radiator location.   Otherwise, if you need the radiator where you are trying to have it then make brackets to hold in there and cat and shape / profile the lower cowl to suit with required movement clearances so the radiator shell is not abraded with contact movement of the cowl; such will be worth the extra effort.  Cheers and enjoy the build, you're getting closer with every bit of work.

[facthunter]

Generally it's the easiest shape with a tank each end and oval tubes connecting. Honeycomb can be made round because the flow is omnidirectional. Oil coolers on many Radials are beneath the motor and ROUND..  Nev

[skippydiesel]

43 minutes ago, Old Koreelah said:

Who says the “radiator” has to be rectangular? A home-made exchanger could be made to fit the available space.

Most are rectangular . Could also be a square. Much much easier to fabricate a radiator with strait edges   I have seen rectangular radiators in a  longitudinal curve 

 

At the end of the piratical day, its what will fit the space available AND deliver adequate cooling. 

[Marty_d]

Thanks everyone - think I've got it sorted now.

Did some more holding in position, and yes it's best with the oil cooler at the front and the radiator parallel with the front exhaust runs but offset from centre to avoid the exhausts.  Pics below show - oil cooler is dark, radiator in aluminium colour.

That's not exact position but close.  I'll have to jiggle it precisely then I can draw up the mounting brackets required.  Luckily there's the M10 holes either side of the gearbox for the oil cooler (which only mounts at the top - no provision at bottom for any attachment), and the front and rear holes at the bottom of the engine for the radiator.  The rear holes are used for the engine mount, but if I put an aluminium spacer inside the engine mount recess then a longer bolt can also attach the radiator bracket on the outside.

 

Edited May 14, 2023 by Marty_d