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Dual radiator?


17 posts in this topic

Posted

Hi all. My Avid 582 mod C has two radiators under the cowling. One smaller in front of the cylinders and one bigger at right side (extra cowling on the outside). This system is quite heavy and I would like to reduce it. I know about the mod about mounting a new radiator under the belly I front of the landing gear, but this is to big if a mod for now and I also don't want to loose the cabin heat system from the side mounted radiator. 
I was thinking about removing the front radiator, has anyone else done that? Does anyone else even have two radiators? On my T-bird2 I only had one radiator and that was enough. On the other hand, the side mounted radiator isn't that efficient as a front mounted one... I guess I just try to remove the front one and see what happens to the water temp.

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Posted

Pretty sure they were both put in there for a reason.  Are you just doing this to try and save a little weight?

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Posted

Yes, to primarily save weight but also to get the CG further back. I only get about 60C /140F in water temp. When I cover up the front radiator it doesn't get any hotter, so the water pump is pumping around a lot of unnecessary water. 

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Posted

Those temps are pretty low, Anders. What is your ambient? My 582 would overheat (with 2 nose radiators in my D model) in climb at any ambient above about 60 degrees F, and would overheat wildly in cruise if I installed the heater cone on one radiator.

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Posted

My ambient temperatures are around 20C 68F. I think that the dual nose radiators would work fine if they had proper duct to lead the airflow and make use of the ram air pressure drop and consequently cooling effect. I have seen the old single mod C radiator work fine tighter with proper ducting. I will try to block the front radiator of after testing my water temp sensor in boiling water. My Kane was build in Italy and it's hotter there, so I guess the dual system as needed there.

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Posted (edited)

So now I have removed the small radiator and the WT is up at 80C at 20C ambient. 2kg lighter at the nose and a better flying aircraft. At climb I reached 90C. I guess next step would be to replace the side radiator with a belly radiator.

Edited by anders.stenhammar84@gmail.

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Posted

Here is my belly radiator. It is fastened with two steel u-bolts that hook over the diagonal floor members, right through the thin plywood, and then mount the box beam. I had to drop the radiator 2" more with the extra end pieces, because when close to the belly it was much less effective. The radiator is s used Kitfox one, from Edmo, the hose is 1" silicone high temp from Amazon, absolutely leakless. I am currently working a scheme to use a flap to vary the cooling from the cockpit.

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Posted

Very nice information. I actually have one of those radiators on the shelf from an other aircraft. I will mount it and see how it goes. Just need to buy some hoses. But does the hoses go straight up to the engine or is there any filler neck cap on the way?

 

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Posted

Anders

the right hose goes to the water pump outlet and the left hose goes to the bottom of the right cheek radiator. I used 1” silicone hose which fit perfectly.

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Posted

Must have a filler cap in there somewhere.... Also a catch bottle for expansion of the antifreeze when it gets hot I would think.  JImChuk

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Posted

So now I have installed the belly radiator and removed the side radiator. I will test it this weekend. The right hose from the engine top has a T connection for the expansion bottle that also has a pressure filler cap on it. If this is not enough cooling I will mount  the rotax912 oil cooler parallel with the belly radiator. Hopefully that's not needed. 

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Posted

So great success! The belly radiator performed really good! Today's flight test had ambient temp at 16C/60F. climbing 1200fpm at 50mph and still only 75C/167F water temp! But, at cruise the temp went down to 60C/140F. I think that the next step would be to install a thermostat. 

I am very happy about this. I managed to reduce the empty weight more than 5kg/11lb of radiators, hoses and water. I also got the CG further back. 

I noticed a higher cruise and more efficient elevator and lower stall speed! This forum is great!

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Posted

Now I have removed the side mount in stainless steel parts and the side radiator cowling to loose more weight and drag. Doing some flight tests and haven't noticed any big difference but I am still happy to loose the weight and the ugly cowling.

Now it's time to sand the fiberglass sheet and paint it. Some day I might do a proper job instead of the riveting. 

I also bought a GSC 3 blade 66" prop and are wery happy with it, even though it was a pain to adjust the pitch. I had to use my smartphone with an leveling app that that 0.1 degrees resolution. 0.1 degrees at 24" out from the hub gave me about 200rpm. I set it on 6100 max static rpm and that gave me 6500rpm at climbing. Spark plugs got a light chocolate brown colour.

 

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Posted

Wow, this sounds great!  I once saw a little oil radiator sitting uncowled inside the fan duct on a DC-10.  Needless to say, I was shocked that it had no cowling to reduce its drag.  It may be that the best drag reduction from even an optimal cowl is not that large!  I am in the process of evaluating the drag reduction for closing up unnecessary openings in the front of my engine cowling.   The bellyrad may not be a bad solution after all!

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Posted

When I talked to steve winder years ago about putting the belly rad on mine he said the air there was so dirty that its not going to cause much for drag.  That's also why we have to either put a shroud on the belly radiator to make a scoop or drop them down further to get them into good airflow.

 

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Posted

My bellyrad, which I think was for a Kitfox, has only a 1/4" standoff,  and cools my engine nicely.  Cruising I am seeing about 140F.  In climb it gets up to 160F.  Maybe a smaller radiator would need more standoff.

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Posted

Finished painting my cowling now, happy with the result. It's a quick fix so it's ok. I will try to tape if the two holes under the prop and get a spinner also, guessing that will do some drag reduction also.  

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