Motors slow down when they get hot. It is a fact. Motors burn up, melt... and potentially destroy your ESC when they get hot. Its a fact that I'd rather not have experienced. Should I retro-fit my T with watercooling? My Iowa had it, and I never had a hot ESC OR motor. The motor always ran strong until the battery wore out. That all being said. It is a bit of a pain. Cutting the belly of the T, sealing it... running the tube. Then on occasion, the tube gets plugged. It is cool though.
Depends on the motor you choose and how much heat it puts off. those fan cooled mabuchi's probably don't need it, and watercooling an outrunner brushless is not really feasible.
Assuming you get good news from mtroniks, I'm going brushless. (How's that going BTW?) So I'm looking @ the watercooled inrunners... ala.. http://hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=8595&Product_Name=2040SL_4800kv_Brushless_Inrunner_%28WaterCooled%29
I'll be honest. I have not tested inrunners for combat. Considering their construction, there will be no good way to dry out the guts (generally, with most in this size range) unlike the outrunners. Which means that if one sinks, and gets water past the beariings, the iron core will corrode away while on the shelf. While the bearings may be sufficient to seal, I wouldn't bet on it, but on the other hand, the prices have come down enough (particularly on the one you see there) that it may be worth it. another thing to keep in mind, is that that motor you linked to, may run too fast for your gearbox at 12V. I ran a ~1000kV motor on 6V in the tirpitz when I had her at ~0.9:1 if I recall correctly. If ran on 12V, I would have been running a ~1.5-2.5:1 gear ratio (somewhere in that range, depending on how she performed). With a 4800kV motor, you may end up needing something in the 10:1 range, depending on prop selection (unless I can find any spares I may have floating around for the T)
OK, so inrunners are out because of the likelihood of it rusting. So, looking at outrunners.... TGY Aerodrive 910kV; so if your numbers are right... @12V it should land somewhere around 1.5~2.5:1 gear ratio... which is perfect for my bc gearbox, default set @ 2.5! 3Cell LiPoly (its rated @ 3&4cell) is right around what my 12V battery will produce. So the motor is 12V capable. So... It says 310W; which at 11.1V & being a DCmotor, is calculated to ~27A. Question is what does "Rated Power" mean with brushless? I assume similar principals apply as brushed motors... so a motor at stall will pull more current than at any other point, is that its rated power? jks
No. rated power is what it will do forever without cooking itself (generally, although most rc stuff has little margin above that value). Any stalled motor will cook itself if you apply full power to it long enough The motor will pull only as much current as necessary to turn the prop, until it stalls. I suspect that motor is true overkill for this purpose and would serve you well, especially if we get true current limiting from mtroniks. -Greg
Whoever said you couldn't water-cool your outrunner motor? All you have to do is poke enough holes in the sides, and your worries about motor temperature will instantly vanish
Why doesn't mTroniks get back to you!!! I really really want to know! Damn build and bull session! Now I got a real need to be driving that boat!
yep me too. I will try to fix that motor lead, add the reinforcing, and get the wire layout figured out. I should have borrowed one of your solenoid valves to fit as I could have had that sorted out too.
I have water pick up tubes that are connected to hoses which connect to cooling coils wrapped around the motor cans. The water is discharged through ports on either side of Yamato under the flight deck. Been working flawlessly for 8yrs and my motors have not cooked. Running time been excellent. The Tubes are located behind each prop and pick up the water when the ship is moving.
Doesn't a bilge pump require water inside the boat in order to pump? I would think that if you take your cooling water straight from the bilge pump, you would have a few minutes at the start of every sortie (and during free-sailing and practice) where such a water-cooling system wouldn't have any water to cool the motor with.
I do that to cool the pump motor, it seems to works fine, might as well use the water that is going to spray out of that hole for something. I don't water cooled my drive motors, I almost did when I built my first VDT but it didnt need it so I didnt finish the system. If I ever need to its a good idea and I know people have done it effectively. I have packed ice on top of my motors to keep them from burning up, I dont recommend that except in dire circumstances.
