Endbell Heat Sink

[Shooter]

Hi folks. Anyone out there running an endbell heat sink? I'm curious as to how well it works for you.

I found this sink on ebay. It required some mods (milling the slot for the wires) and a few holes to thread in the end bell.

Seems as if the motor heat is a serious limitation for running bigger props in P-spec. I ran some monster props last week and was running mid 50's, but sustaining that is going to require some serious cooling upgrades.

Other idea includes a similar heat sink, but the sink is made of copper and water is in direct contact (going to require some machining time).

Any help/info would be great. Thanks.

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[T.S.Davis]

Pete, you can't tap the endbell like that and stay legal.

[Shooter]

Ahhhh...geeeeeshhh....and I was so happy last night.

So if I clip it on or attach it to the cooling jacket somehow, then it's legal?

[T.C.]

Just make some straps to hold it on, or make one that clamps onto the end of the motor ?
T.C.

[T.S.Davis]

You can add water cooling as you see fit but you can't modify the motor from factory. We debated this to death last winter. Can't remember the thread.

I've tried other things to keep the motors cool too. Nothing that worked well. Looked cool but didn't do what I wanted. I always wanted to have a CO2 canister with some sort of control valve cooling my motor but not very practical. haha

I once had designs on putting an actual radiator in line on a scale boat. The radiator was going to be in the turbine. So the water would come in through the pickup, go through the radiator, and then through the components. Never got that far.

Liquid nitrogen? Super practical.........or not. I think the book says "water" cooling anyway.

What if you put dry ice in that canister you built? Run a coil of aluminum through your chamber and use the dry ice to cool the coil inside the canister. Seems reasonable.

Honestly though, for all that effort you would be better off to find the perfect prop for your setup. The time it takes to build a better mouse trap would be much better spent learning to manipulate the propellers.

[Shooter]

I've tried other things to keep the motors cool too. Nothing that worked well. Looked cool but didn't do what I wanted

Good point. I think I'm definitely in the realm of 'looking cool, but having little to no effect'...but that dang endbell always seems so hot, there's got to be some advantage. I've tried running every prop in the book from M545, X645dt'd, X645 cut to 44mm, Prather 225, H5, you get the idea! Point is that I can get the speed in the mid 50's, but the heat ALWAYS comes with it. Windings near the endbell (highest temp location I've observed) at temps in the 140-150° range! Maybe this is just the limit.

Water has been so hot lately that any change I make is like putting perfume on a pig. Simply not enough delta T to work with. Your approach of trying to cool the water might be the most effective. That radiator idea is sweet. I’ve seen them for computers.

I was running a lot of 'ice cube' tests up north with that canister and I did eventually get it to work (graph attached). Doesn't maintain the delta T for a long time, but enough to make a huge difference. I just don't see it being practical now that I've lived it. Is that legal BTW??

IceCooling.pdf

[T.S.Davis]

Yep, still legal. My canister setup leaked like mad. That was 2004 though and I think you're approach is actually better than mine was.

Try an M445 and add some cup to the trailing edge. Another good one to try is an M545 that has been reduced down a bit to maybe 44mm.

Want to make your head hurt some more? The prop you can get away with on our pond might not work on the next pond you run on. Different crap in the water. More iron? Water dye? Elevation above sea level? Beats me. I don't know how to quantify it but it's real. You have to test on the pond you're going to race on. Makes open water actually matter. Tom burned up some stuff in Canada that he races on our pond with no trouble. How come? IDK!!

Point is, get close, practice turning, and figure out how to be in the right place at the right time to capitilize.

Oh......and get signed up for the Shootout already slacker.

[properchopper]

While I would rather poke myself in the eye with a sharp stick than start another granfalloon-fest on spec motor compliance issues, I thought I might suggest a solution that "some guy" uses to address the over-excited electrons in the endbell and wire entry thermal choke-point. Yes, sports fans, there's no supply of fresh air inside a sealed hull, but according to a law of thermodynamics that I just made up, air accelerating out of the fan is substantially cooler than the residual trapped air.

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[line6]

according to a law of thermodynamics that I just made up, air accelerating out of the fan is substantially cooler than the residual trapped air.

lol Nice


Jason Sims

[T.S.Davis]

Tony, that's beautiful.

Pete, the cooling effect you are gaining from the canister is likely negated by the fact that you're carrying a half pound of water with you.

I did the math on this a while ago but if you assume 50 mph around a 40 ft. radius turn (if there was no slip) then you're pulling 4.2G. So your 9oz. of water now ways 37.8 oz or 2.36 pounds. You may have the same straight away speed but in the corner......not so much. Coming out of the turn you're getting hosed by the guy that doesn't have an extra 2 pounds of boat but does have the same exact power you do.

Let say it's only 40 mph. Still comes out to 1.5 pounds of extra weight. People like to say weight doesn't matter. That's true......going straight. G force is real too.

Doug Junior told me once you don't win a race in the straight. Fast, smooth, predictable turns wins races.

[T.C.]

Why not put the fan blades on the shaft side and blow air through the motor.
T.C.

[properchopper]

Why not put the fan blades on the shaft side and blow air through the motor.
T.C.

Terry,

Two reasons :

1: more free space on wire end [KISS principle]

2: fan output addresses the most fragile hotspot - the "legal" juncture of the three motor wires where the "legal" shrink bundles them together creating an heat-additive effect, often melting the shrink and causing the motor wires to touch, and then

Inspection of heat-kaboshed motors where the insulation stayed intact (or in those shrinked-enhanced motors before it became a no-no) shows degradation of the coils (blackened where the coil wire laquer insulation overheated) occurs just inside the wire-entry endbell, so that sems like the most important area to keep cooler.

We're running four P-Ltd Hydro heats at Legg this coming Saturday. Was there yesterday & it was hotter than a laptop computer keyboard spell-checking articles for a Hip-Hop magazine. No bigger than an M445 & bringing spare motors

[T.C.]

I was thinking if the motor in general was cooler the "hot spot " would also be cooler.
Guess I'm not thinking correctly ?
T.C.

[Shooter]

I did the math on this a while ago but if you assume 50 mph around a 40 ft. radius turn (if there was no slip) then you're pulling 4.2G. So your 9oz. of water now ways 37.8 oz or 2.36 pounds.

Good call. Larger mass accelerating towards the center resulting in larger force outwards....and that aint where I'm trying to go! The "sloshing effect" probably isn't helping either.

I like the fan idea.

[line6]

Kinda irrelative, by the same math a 12lbs boat would b 50.4lbs. To me adding 9oz is adding 9oz. I could b wrong...

Jason sims