Direct drive outrunner with direct water cooling


#216

Thanks Giga, Ill take that into consideration! The motors aren’t sensored.


#217

Can u please share two blade prop design that you tried? I would like to try it with my sk3 149kv


#218

Sure, It isn’t my design, it is @pacificmeister 's design. heres the link:

https://a360.co/2lCVJ6U


#219

Now it makes sense to me, also aligning does not play a role, as each of the VESCs has its own motor.


#222

Gave it a shot with a single motor, which wasn’t anywhere near powerful enough…It got me to maybe just over 5kph.

So I moved on to this design with an SK3 6364 190KV in front…

running on 6S it was extremely powerful, I can easily say over 25kg of thrust, when I was kneeling on the edge of the pool with both arms holding the front of the board, my whole body was almost sliding backwards on the concrete. When I tested it in the pool, It was not getting me up on the plane, but there wasn’t enough space… it clearly needed a bit more thrust, So i’m about to try it this afternoon with pacificmeisters 3 blade propellers.

I will be sure to post a video here if it works

I think this powertrain is definitely powerful enough if the board has more capacity so it doesn’t require so much power to get up.


#223

Phantastic job! Might have better efficiency comparing to a single motor (the same principal as in multirotors).

What do you say @jakebarnhill1 to incorporate very cheap setup with 6-7s two batteries and 5065 motors, each 1500wt. As per links as follows, below.
With appropriate two blade prop?

N5065 320KV 1820W Outrunner Brushless Motor For Electric Scooter Skate Board DIY Kit

Red Brick 125A ESC Brushless ESC BEC:5V5A UBEC125A


#225

I’m sure that has a ton of power but two open blades especially one that close to the back of the board where you are crawling up and likely to squeeze the trigger by mistake is deadly. You best find a way to enclose those blades or this could happen but much worse: Nice cut from propeller


#226

@vefoil that is definitely a serious concern! I knew I should make a duct for safety but you’ve motivated me to do it for the next ride…

It just didn’t have enough power to get me up on the plane still… Do you think that a larger surfboard that is more buoyant can make a lot of difference? The small foam board I’m using is submerged when I lay on it in the water.


#227

@Antonbit The motors I’m using are extremely cheap at $60AUD each. I don’t think that the motors you linked would have enough torque at 320KV, my 190KV motors are still to high…

But if it could work with cheap ESC’s like you linked that would be good for lowering the cost!


#228

Great to hear! I cant stomach the thought of guts getting sliced open or private parts - shark bait! lol

With direct drive setups the proper foil and board it 50% of the setup, if those two are not matched for low thrust setup then your toast. A planning hull is critical, the wider the back of your board the better, and flatter the bottom as well. a surfboard that tapers in at the back won’t work with the direct drive.

Direct/Jet drives are safer and sleeker with much less drag than a large prop and duct, but the trade-off is a much wider board, little longer, and a flat bottom.

What size is your board, and what foil, also what is your weight?

And yes, if your RPMS are maxing out then you have left over torque to use and a 3 blade should provide more thrust.


#229

@VeFoil The board I was testing on is a small foam surfboard, which i was testing with dual motors as you saw above but no foil. My new build which I’ve started already is with the parts below. The only thing I’m concerned about is the size and buoyancy of the surfboard that I’m using.

My board is a 6’2 surfboard, it has a flat bottom and is made of fibreglass but certainly isn’t very buoyant…

And the foil is from aliexpress, its a nice big wing and a few others on here are using it i think…

I weight 72KG

Do you think I need a better board?


#230

Hi Jake, I use also an old surfboard it’s even smaller and I am 10kg heavier. To start it’s a little harder (power and skills) but once your up on the foil it has less inertia.
One of the drawbacks is the lack of space for big batteries


#231

I have no doubt you will need a board that is 28+" wide, and it must be wide at the back to get planing, that board will plow the tail through the water and prevent you from getting up on foil most likely. But if you have not tried it, test it out first, your only 72kg, thats lot lighter than me 115kg :slight_smile:


#232

Thanks @Clarin , that’s good to know. Do you know roughly how much power it takes to get up onto the plane?

I guess the only advantage is less inertia.


#233

Cheers @VeFoil, appreciate the help. Ill give it a try, hopefully within the next few days. If it doesn’t work, do you think a SUP would be a good type of board to mount the foil to?


#234

Here is the post where you can see my power curve, I guess the other advantages of a smaller board is less aerodynamic drag, less weight, more nimble, tighter curve, and easier to transport. (My next one will be 150cm and 50cm long and will have more volume for more battery)


#235

NP, yes SUP is what that foil is meant for and if you cut an SUP back off so its wide and shorter, you should be rocking!


#236

Thanks @VeFoil and @Clarin

making some progress now, Just have to design a duct for each propeller :confused:

Motor stators epoxied:


#237

Nice job on motor epoxy!!!


#238

Its amazing how these simple ideas grow. Thanks for your further development, this was intention. Although i think the coating shown is too thick.