Making a water-cooling coil for a Cox .049 engine

roddie Sat Apr 20, 2024 12:06 am

I cut a 10 inch length piece of 1/8" OD soft-copper tubing.. and wound it around a 1/2" twist-drill's "shank".. (which is 1/2" diameter...) I used the drill in my drill-press to drill a hole in a block of wood.. for the same twist-drill to fit in.. to serve as the "winding-post".

Making a water-cooling coil for a Cox .049 engine 20240418

It was not a difficult or high-effort job. No hint of creasing anywhere on the tube.

Making a water-cooling coil for a Cox .049 engine 20240417

I used some 3/8" drive socket-wrenches with a short extension.. to gradually increase the inner-diameter of the coil.. until until it's just slightly smaller than the outer-diameter of the cylinder/head. The soft copper is easy to work.. once you get a feel for it... (recoil/springy-ness/memory). Once it's close to the right diameter; squeezing both ends backward; spreads the coil open.. allowing the coil to be pushed onto/over the glow-head. When released; the coil "recoils".. and the cooling-fins on the cylinder/head "key-into" the coil-separations to help hold the coil in place. I was pleased with the way it worked out. This is all new to me... and there's been lots of hiccups along the way. It's always a good feeling when something comes together as expected.

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balogh Sat Apr 20, 2024 12:46 am

Very nice and simple, Roddie, congrats.

Due to the recoiling spring effect the copper coil remains in a fixed metallic contact with the steel fins, even if temperatures rise, and the slightly higher thermal expansion coefficient of copper than of steel would work to loosen it..

To enhance heat transfer, some aluminum foil - used in the kitchen - wrapped around the fins in 2-3 layers and stuffed in between the fins before the copper coil is pulled on the cylinder would increase to contact surface of the coil with the fins ? (Just a wild thought of a member involved in heat transfer engineering)

MauricioB Sat Apr 20, 2024 2:58 am

Roddie, mate, very good job.
I want to highlight your photos that speak for themselves, you have a way of presenting your works that are textbook, that is, in a very practical way to interpret.
I'm building the Citabria and by the way, as I'm working on it, I remember the way you present your works, you are in my thoughts friend! Thumbs Up

getback Sat Apr 20, 2024 6:36 am

Good job looks very uniform and will hopefully do the job . Very Happy

1/2A Nut Sun Apr 21, 2024 5:10 am

Proper dia. tube using lower weight aluminum yields 5 coils for functional cooling.

Making a water-cooling coil for a Cox .049 engine Resize27

Making a water-cooling coil for a Cox .049 engine Resize26

davidll1984 Sun Apr 21, 2024 6:36 am

1/2A Nut wrote:Proper dia. tube using lower weight aluminum yields 5 coils for functional cooling.

wonder if aluminum would be more effective than brass in dissipating heat? Probably and also slightly lighter cool stuf Thumbs Up

rdw777 Sun Apr 21, 2024 9:50 am

Great job on the water coils roddie!!…. Brad’s marine engine looks like a go getter too!!
Boats can be a lot of fun if you’re set up for them and have a place to run them…

Robert

roddie Sun Apr 21, 2024 10:39 am

MauricioB wrote:Roddie, mate, very good job.
I want to highlight your photos that speak for themselves, you have a way of presenting your works that are textbook, that is, in a very practical way to interpret.
I'm building the Citabria and by the way, as I'm working on it, I remember the way you present your works, you are in my thoughts friend!

Thanks Mauricio! Illustrating the methods is part of the fun for me.. especially if it inspires deeper thought/expansion on the subject matter.

roddie Sun Apr 21, 2024 10:49 am

getback wrote:Good job looks very uniform and will hopefully do the job .

There's a fella that lives down the road a bit.. who also enjoys model boating. He builds custom lower-units for making outboard-engines from .049 FRV glow engines; "Spitzy's" in particular. He also made NVA's for them on his lathe. He's been somewhat of an inspiration for me.. in re-igniting my model-boating interest. We live in an area that rich in lakes, ponds, rivers and streams.. which makes running a model boat a lot easier than flying a model airplane.

roddie Sun Apr 21, 2024 11:35 am

1/2A Nut wrote:Proper dia. tube using lower weight aluminum yields 5 coils for functional cooling.

Great looking engine Brad! I do have some aluminum tubing.. but I don' think I can fit a 5 coil wind without it interfering with the exhaust throttle's function. Huh...

I also don't think that my reed-valve engine will run as hot as your high-performance Tee Dee engine. I'm hoping that mine will have enough power for the 22mm prop that I'm planning on running.

roddie Sun Apr 21, 2024 11:43 am

davidll1984 wrote:
wonder if aluminum would be more effective than brass in dissipating heat? Probably and also slightly lighter cool stuf

David, I had the option of making a cooling-coil from either Brass, Copper or Aluminum.. but had an abundance of the Copper. I posed the question to the internet; "Which alloy dissipates heat best?" Copper and Aluminum came up as answers.. so I opted for the Copper.

roddie Sun Apr 21, 2024 12:00 pm

rdw777 wrote:Great job on the water coils roddie!!…. Brad’s marine engine looks like a go getter too!!
Boats can be a lot of fun if you’re set up for them and have a place to run them…

Robert

Thank You Robert! Yes... the fact that there's a myriad of accessible aquatic areas immediately nearby to me; makes model boating activities more attainable.. as compared to model airplane activities. I enjoy the designing/building aspect of both.. but when it comes down to the application; the boats will definitely provide a return on investment.. in the way of FUN!

1/2A Nut Sun Apr 21, 2024 9:28 pm

4 coil piped speedy reedy 1996 Killer Bee .049,

Making a water-cooling coil for a Cox .049 engine Cox_0413

roddie Mon Apr 22, 2024 3:07 pm

Hi Brad, I'm noticing that your cooling coils pictured are oriented in such a way as to route water to the "top" of the cylinder before spiraling the water downward. Does it matter whether the water spirals upward or downward? Is the top-end of the cylinder the hottest part.. or would that be down lower at the exhaust ports?

1/2A Nut Mon Apr 22, 2024 9:27 pm

Yes ground up to hide the water feed line, the top of the coil ultimately rotated to dump to the side.

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