80100 direct cooling

Thanks, in your link is a picture with good results. Maybe another design prop with ring and testing once again ?

May be with a thinner ring like in the paper, it will reduce the extra losses and you can get closer to regular prop efficiency…
I’m not sure how printable it’ll be though…

@superlefax, did you give it another try?

Well, I could not even got to decent speed. The amperemeter showed over 100A for 20km/h. I was really surprised on this. I’m not really sure what exactly caused that drag.

That’s why I gave up on that one.

But of course its always a good idea to try it again with a different shape. It would be great to find a working solution which maybe has less drag than a fixed duct.

What about blades offering curved but short winglets at their extremities so that there is not cutting angles if in contact with a person or an animal ? Like planes in fact ?

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Here the illustration of what I had in mind: scimitar blades from modern submarines. You will notice that to bring the safety aspect, the winglets must be bent towards the opposite side of prop rotation direction.

In fact rotating winglets during rotation create a solid ring. Of course, the blade extremity must not be sharp and dangerous like scimitars. They coul be thickened like an olive.

Applied to @foiledagain 156mm prop, this is in yellow what it would look like adding a tiny appendix to smooth the edge:

found the submerged data: S9tim's 80100 direct drive
So it’s something in the low 900W

I just changed laptop so my recorder setup is messed up… but from what i saw, when trying to fix my receiver full speed in air is in the 160W range
i’ll try to run it wet soon just to be sure to compare apple to apple

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Complete test done tonight all in a row with the same motor.
graph is from my elogger and I was checking with a HTRC wattmeter

First 2 are in air:
120W 4500 rpm
I’m starting to wonder if my motor is actually a 80KV… and now that I think about it, previous 160W was with the prop

Next 1 is in water without the cap to block the holes act the front of the stator
1100W 4120 RPM

Last 2 are with the cap:
860W to 900W 4200 RPM

There might be more to gain with a better car probably.

the RPM spikes before 2 and 3 are when I plug the batteries I guess…

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It’s not 80Kv looks more like 95-100ish…

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My Test for spinning under water was 825W, but battery was only 44,4V (not fully charged).

I guess with full battery, i would be in exact the same range


Had my first run yesterday. I did not waterproof the wires. Normally it is not a problem but now they are so close to eachother it is a problem. It felt like sync problems. But anyway I still had enough power to foil. But I was laying on the board and really hard to stay in balance. I used my Fone hydrofoil for kitesurfing and that is working fine. But this seems to be much harder to learn. 14s at 130kv with pitch 5 is probably way to much rpm also and therefore to hard to control the throttle

Not a foil question
I really want to build a small electric boat for my kids, thinking about building it from the Glen-L MiniMaxed drawings (https://www.glen-l.com/designs/outboard/minimaxed.html)
This boat is to plane with a motor of 5hp. Will the C80100 engine and propeller you use be enough to make this boat plan with a kid on board?matt-fitzgibbon-001

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Should be fine.
Here is the boat I have built for my daughter.

It is powered by 56114 with gearbox.


it’s actually easier to balance standing up than lying down :slight_smile:
What remote are you using?
It makes it much easier if you have a “cruise control”. on my remote, I have a trigger that arms it and then a thumb wheel to accelerate/decelerate. When I let go of the wheel, it keeps the speed constant. and if it let go of the trigger, it stops everything.

It should be ok. My board is a bit smaller and and lighter… but i’m heavier than a kid :slight_smile:
and i get it on plane with no problem.
The only difference is that you’ll have higher currents continuously as it won’t flying, but with a cooling pump it should be a problem, will only impact the autonomy if think…

@foiledagain Did you ever try your 2 blade propeller? I ran a print off and run over the weekend and it works very well. I’ve got some temperature issues in my esc (its under size, nothing to do with the prop) but could fly along with the 2 blade version.
Also I think its more efficient as I ran longer before the thermal cut off kicked in. There’s a video of me face planting the river using the 2 blade in my build thread.

Where do I find this 2 blade propeller?
My board is almost finished and I tested it before without board 10kw input that was no problem. Now all is in the board and I get something that looks like timing error again. But maybe the motor, or wire connections are not waterproof anymore. If I now put the motor under water i measure per phase wire 1 m ohm or 1 M ohm is that too much maybe ? I can ride 6kmh and it will stall because it loose sync

Its designed by foiledagain. It was originally a 3 blade but has since changed to a 2 blade when you open the fusion file. Not sure if this was on purpose but it works well. I’ve had a few runs on it, but threw both the blade at once! I did a static test in the water and I guess the extra force of not moving the board forward was enough to break the both clean off!

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Thanks I will try that. I did a no load test. Only the motor in the water full throttle is 4700watt with the cap on top 3700 watt
No prop. That was with open phase wires. So I made phasewires waterproof and still same results. 58v at 130kv is about 7500 rpm way to much. I do measure about 1 to 10 mega ohm when having a probe in the water and at a phasewire. This can not be the problem right?

The smaller 3d printed c80100 experimental modified prop is giving me out of sync and the aluminium 7 1/4 pitch 5 is running good. Maybe the 3d printed prop is too much pitch? Im a bit stuck now.

I’ve never tested resistance with a probe in the water so not sure.
I do have to shift the motor timing to around 20 deg to get around sync issues though. This is with the 3D print prop.