Water-Cooled, 63mm, 8kW

I stumbled across this while searching for a centrifugal fan for my Turnigy 6364-280.

http://littlescreamers.com/id57.html

The kV is high (650), but it looks like a low-volume outfit that might do a custom wind or maybe let you wind it yourself. $105 shipped from USA sounds pretty good.
I'd still rather just get the fan if anyone has a source. I emailed espritmodel.com since they have one for a 50mm Hacker for $7 - haven't heard back yet.




Motor KV-650
8mmShaft
Max Watts-8000
10-12s batteries
Props 3.2 3 bladed

Littlescreamers 63mm Water Jacketed Outrunner Boat Motor

This Large Water Jacketed Outrunner was designed for big boats 40-90". It will perform well as a drop in HP replacement for the Weed Eater type gas boats. Designed as a racing motor to run against the gas and will be competing in the racing scene beginning 2010. Testing so far in a 40+ Race hydro we are running 65-68 MPH and completing 7+ laps on 10s. This is very exciting for a low cost alternative motor to be running with the $600 Modified gas motors Testing continues and I will update soon!

How is it watercooled? I can see the windings...

The shaft collar is extended and ribbed, then there is a housing slipped over it (the gold cup on the right side of the first pic). You can see the two black rubber O-ring seals that the water shroud slips over. Since the can spins, the water shroud is over the only exposed stationary part, which has been enlarged compared to the conventional RC motor baseplate shape.

I think this is actually a very good idea. Somebody get ahold of that Hobby King guy (Australian?) and have him start making and offering 63mm and 80mm baseplates like this. I'd like to see a good air-cooling solution too, but more options is a good thing.

It looks like it just uses the fixed end of the motor as a water cooled heat sync. There doesn't seem to be any cooling on the stator or the windings much beyond the cooling block on the fixed end.

Carl

I have to admit, this seems like a good way to do it! You could even simply add a section like that to your existing motor if you got a longer output shaft! It is the coils that get hot right? If so this seems like a simple solution! You could spin something like that up in a few minutes on a lathe!

Very cleaver.. unlike some water cooled motors, that one still has the normal air cooling too !
It could be even simpler if you took the drive from the other end ( as most bikes and aircraft do ) then you could "cap" the other shaft end inside the water jacket...not needing the extra bearings and seals, :wink:

Why not making a hollow shaft?
I thought of drilling holes from both ends, but leave it solid in the middle. Then drill radial holes right next to the solid part, so the water fills the area between shaft and stator.

...or even better:
Why do we need a single piece shaft at all? Usually we don't have axial forces on the shaft like the RC-propeller guys.
Make it a hollow two piece shaft ( two bearings on both ends) and flood the ( finned ) statorholder completely. Especially for the motors with skirt bearing it wouldn't be a problem. If only I could get my hands on naked stators and a lathe.....
-Olaf

I don't like it. It takes an RC motor and makes it longer, what we want is more of a pancake shape like the Joby motor. It doesn't look to have a corkscrew effect either so how should you move the water? With an external pump? Let's do a parts count for water cooling: dc-dc convertor for pump, computer CPU radiator, lines, and external pump. Then if any of this stops working, you will burn out your motor. A thinner option would be to just add cooling fins to a thick mounting plate. Also, an 8mm shaft is kinda dinky, definately wouldn't want to drill any holes in it.

I hear ya, good points. My favorite version of cooling an outrunner so far is on the white Schwinn one member here did. A really nice heat sink on the outside of the motor to dissipate heat... You could even do that, AND a heat sink in the mounting plate..

Interesting, thanks for sharing it!


-JD

Whiplash, Sosauty's ToyRacer is equiped with an astor 3210 & that spiraeling heat sink...

I been pondering active cooling for outrunners for awhile. (it really is unnessisary except in extream applications)
like this:
http://www.youtube.com/watch?v=OBTt_NZpyfs&feature=player_embedded
That watercooled set up is better than nothing. The design of the motors themselves complicate a few things. Heat form the stator has to be transferd (conductivly) to the bearing tube & then again to the mounting face of the motor. Still had the windings near "fail" temp after a 45second run (the wire is rated to 200c)

I like the idea of "forced air" but any blades or foils afixed to the ends of the can are functionaly usless. An independent tangental "pressure" blower would be the only way to force enough air volume through the motor confines to have a measurable effect. That combined with a spritz of atomised soft water would really shut down thermal runaway.
I love the Joby's open architecture just for its exposure to the ellements for cooling. On the negative, outrunners or open inrunners wont like being subjected to the tera firma ingestion you get in an off-road application. I have tried it & its not promising.

My last thought would be a partial imersion in light oil in a closed system. JH did some testing with full imersion & the parasitic drag in heavy oil was dramatic. Just need more time to play.

All of my outrunners use a squirl-cage style fan on the rear of the can to draw air through the motor. This reduces heat tremendously.

Matt

Thud said:

My last thought would be a partial imersion in light oil in a closed system. JH did some testing with full imersion & the parasitic drag in heavy oil was dramatic. .

Click to expand...

Hmm ?.. sounds like you just re-discoverd the fluid torque converter.