What a price!!! 
First thanks so much to pacificmeister for opening this forum.
Dearr Flying,
Your suggestion for a custom motors special for our application is the best way.
When you have news that it is available for purchase, please share.
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This ja possible for a while, actually my current setup Works like this with a Cheap 5,5kw outrunner (Doesnt work yet, gonna try Some different props) but there are 2 main problems with this setup:
- The motor pulls a lot of power just running in the water without the prop because of the rotor pushing water around (about 20A without prop in water!)
- The magnets, the shaft and the bearings are not aluminum like the rotor and the stator mount, so the will corrode with the time, so this is ok for prototype testing, especially for inrunners, but for the final version of your foil you should get everything waterproof.
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I like your low kv low voltage direct drive idea. I just heard that the 360kv version of the SSS can only take about 90amps before burning up. So going down with the voltage could be a challenge as amps increase and you will likely have higher peaks. Also elsewhere you will need to deal with more heat, ESC and batteries. I ordered a 360kv and will experiment.
I ordered one as well. Do you have thrust measurements of your current setup? is 27Kg of trust is sufficient to have high stable speed?
BTW in the motor specs it stays for 13000Wt of power! (even more then 500Kv version, so 90amps is a bit low for it even with 14s battery.
Anyhow in order to get 27Kg of trust we need 2500wt of power (as per graph), which is 28-30v giving 10440RPM (but no load), so the question how the RPM will be reduced under 2500wt of load (best is 10440 to 7000 rpm)
So I will start with 8S setup and measure the current
have you considered patterning the outside of the aluminum case to increase thermal dissipation? I would imagine some deep grooves (think heatsink) would increase sensibly the surface area, and with the water flow could improve the cooling.
Good ideas if motor cooling becomes an issue. For me motor cooling has not been a problem with the SSS inside the alu tube so far. The bigger challenge is keeping ESC and batteries cool.
Hello.
I’m doing a efoil with outrunner to. I will ciol my motor by running it in liquide oil
Advantage… good thermal conduction with casing who is in water and no corrosion…
I have already do some teat with or without water and i have only 80w more (3amp) more with water
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Hey Guys. When you install the lip seals are you using adhesives? I’m concerned that without some sort of sealant it may leak given the rough printed finish.
Hey PacificMeister,
I have been talking to a guy from alien power systems and they have a motor that is in prototype and should be ready in 3 weeks. 58mm 100-120kv and around 160gbp is all the info I have right now but I hope to get my hands on one soon…
oh and thanks for all the info you have provided mate.
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Sand it flat. Seal with thin layer of epoxy. And use loads of grease when installing. Should make it waterproof BUT test without motor inside first! Fdm prints sre not ideal for waterproof seals.
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I am building a setup using the same cooling strategy that @Vincentbraillard mentioned above. I have a 50mm 90kv outrunner from alien power systems that will operate submerged in dielectric oil and will allow the stator to be cooled directly at the coil. I will post pics soon but this could be the answer to losing the gearbox and should be an incredibly effective way to cool a brushless motor. Because the heat transfer will be so high and happen right at the coil you should be able to run a motor at 25-60% higher output than what it is rated for allowing for a smaller diameter motor setup to be used. There is no reason this couldnt be used by someone with an existing inrunner setup as well (@pacificmeister) to help keep it cool or to squeeze more current out of their existing setup. Flooded motors have been used for a long time for downhole pumps in the oil and gas industry and we use them at the nuclear power plant I used to work at. I am stoked to give it a shot. Will hopefully have some test results in about a week!
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hi, i have seen a sss 420 kv motor, im thinking i might buy that one instead of the 500kv motor, just starting to collect parts now, i have a 5 :1 ple 60 gearbox, similar diameter to the motor, will be a little heavier but it seems more beefy, has anyone tried the 420kv motor on a 5:1
Does anyone know how much force an inrunner shaft can handle if we were to go direct drive with the load straight into the motor shaft? how many kg can these motors hold on average?
have any of you seen this on ali express! WAY over priced but the specs say 35 kg trust with a 130mm .7 degress prop and a 560kv 36 volt inrunner
It looks to me a bit unreal in terms of RPM - 20000!, however it has low pitch (0.7). I asked the same supplier question about 80mm kort to couple to sss 56114kv, 360kv direct drive (as per his data it has 27kg of thrust at 7000rpm and 2500wt of power)
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Thats some good info to get, 27kg of thrust @ 7k rpm would surely be enough?
Hi. I found this company Lehner Motors, they have 1 called 3080, it’s kv rang from 1050-131 depending on which wind you choose. it’s measurement is 60mm*122mm
In the lower kv’s it looks like they would make a good direct drive
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The supplier of the kort 80mm system confirmed that sss 360kv motor should be ok with this kort (considering 30v - 8s battery setup), so 10800RPM no load and around hopefully 7-8K under the load. So the system should provide about 27-30Kg of thrust in a peak point.
So I just ordered it to build this setup.
The supplier also provides the coupler to 10mm shaft diameter in the package.
I will appreciate if you can comment about 27Kg of thrust - is it ok for our goal?
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I’d just like to share my thoughts on the direct drive idea for debate:
Looking for a low kv motor is really only half the deal. In fact, it shouldn’t be very complicated to reduce the kv on any motor by rewinding it with more turns of thinner magnet wire.
But the maximum torque the motor can generate will not be increased by this measure at all. So unless you change to an inefficient ultra high-speed impeller jet design, the torque would only be 20% of what is needed. I think the motors currently in use already have more or less the best torque/weight ratio that is available. So the direct drive motor would weight 5 times that of the geared motor. Assuming for simplicity that the planetary gear that is added to the high-speed motor weights about the same as the motor itself, the direct drive solution would be about 2.5 times heavier.
Probably the best compromise between high efficiency+low rpm and low weight+high rpm would move towards higher rpm with the direct drive solution since torque is more expensive then and 4% of efficiency is gained by removing the gearbox.
I think despite added weight, the reduced complexity, improved drivetrain efficiency, and durability make the direct drive still very appealing.
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