Direct drive inrunner vs outrunner for e-foil

Hello all,

Thank you for a great forum with a lot of good inputs!

I am in the process of trying to convince myself (and my wife) to start to build an e-foil. My thinking is to start with the propulsion unit and test it out on my SUP. I’m around 90kg, so quite heavy. Have spent some time investigating.

I have thought of below concepts for the propulsion unit and your feedback on my thoughts would be valuable! Thanks.

  1. @PowerGlider concept with a direct drive brushless out runner 6384 treated with epoxy.

  2. @pacificmeister concept with a dry in runner (will not use a gear box).

  3. Use water proof direct drive 6516X in runner from start.

These concepts ofc. has its pros/cons and I guess when 1 and 2 where conceptualized, 3 didn’t exist on the market?!

I have a 3D printer and some various tools at home so the plan is to start from scratch.

  1. I like the idea of running the motor wet for better cooling, need to secure good isolation with epoxy treatment etc for electrical safety and wear/corrosion. Simple design when the motor is treated with epoxy. Will loose some efficiency since running in water. Dirt and sand can enter the motor with a completely open design, should maybe rethink that. 6384 motor is cheap, less that 150 USD for APS motor. Around 4000W of power. Can use bigger outrunner as well.

  2. When it comes to a dry inrunner inside a tube I’m concerned about the heat transfer. Another option is to get a water cooled in runner and feed it with water from the duct over pressure. Since this concept is dry, no dirt, isolated from water - safety/corrosion, requires good shaft seal, high efficiency since running in air. Non waterproof 56104 is also cheap, less than 200USD. Around 10000W.

  3. More or less commercialized product to solve above tradeoffs between cooling/safety/corrosion/power. Can purchase off the self solution with propeller for around 3 times more than alt 1, 2. Much higher power than 6384, around 10000W. How good are they, how long will they last, do they take in water over time, worth it?

Would be great to get your feedback on above reasoning? What option is the best trade off?

there is power and torque (9nm is nice), a 56104 is not even an option

i will go with a 6516x

I’d choose sealed inrunner like 6516x motor any day ovet a wet outrunner due to the difference in noise (i have tried both and the 6516x is totally quiet, it’s so nice)