great built, congratulation !
do you have consumption numbers without prop in air and water to see how much “losses” you lose when going from 80 to 63 ?
(like 80100 direct cooling - #423 by Mat - Builds - FOIL.zone)
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And how much Watt do you need for foiling?
Hey V_S,
i need about 1kW @ 16km/h
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Nice 
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Got my build ready now, charging batterys up, so tomorrow will be my maiden flight on my own board.
Lets see, how René’s foil works with the 80100
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This one
I’ll keep my fingers crossed for your maiden flight tomorrow! Try not to loose your prop 
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Not yet, but i can check it out if you want. Just spinning the Motor full throttle without prop in air and in water? I have just a cheap V/Ameter with hall-sensor to measure the current
exactly, i’m loosing close to 900W just to spin the motor… i expect it to be less with the smaller diameter, but i’m curious how much 
Also i just realized how far back is your mast… i was thinking about that for my next board. Does it affect riding in any way?
Properly secured 
And i got some different size / pitch in spare 
When everything works properly, i am sure, i’ll visit you guys in the north again.
Your lakes are much warmer
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What a great succes, the smaller motor is great. You run 140 kv at 12s. That is a high rpm full throttle. But I guess you never run this high rpm and a no load run onder water and in the air can give a wrong impression compared to the c80100 at 80v.
Right Mat ?
The c80100 modified 3d print prop is 5 pitch ? Scaled down to 0.78 maybe the pitch is also 3.9 I guess ?
actually i don’t run full throttle either not sure of the % though…
and following the my test, it seems like my 80kv is more like a 100kv
i could be wrong, but i think if you scale a propeller in all dimensions, the pitch doesn’t change
Well, you are not completly wrong:
The angle of the propblades does not change, but the overall pitch itself changes by the scalefactor.
Pitch= tan(bladeangle) * 2 * Pi * r
So if you scale down, you change the radius --> pitch is changed equal to to change of radius
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You’ll be surprised with RPM figures. I’ve run the flying rodeo motor at full throttle and get no cavitation. If I remember correctly it was somewhere near 5400rpm under load (motor is 130kv).
By any chance do you have log the max rpm with full throttle under load of the FR motor , I don’t think we are close to this value
55kph topspeed FR = 15,3m/s = 916m/min
With a pitch of 200mm you need at least 4600rpm (without slip).
5400rpm would mean 17% slip. Why not?
Unfortunately I don’t have completely accurate data as I can’t remember when I breached the prop and not. I would need to re-do this when I get a chance.
So this was achieved with a 6" pitch prop on 14S (as far as I know).
That would mean ideally you would need 6015rpm with no slip. Considering a 130Kv motor has and ideal RPM of 7644 at full voltage, this seems completely plausible. I’m not sure why guys are trying to go under 100Kv for their motors. Our uses are very different to a standard boat model.
I guess, guys are afraid of 55kph 
Right, we had very good result with 120-140kv motors good efficiency good top speed no need for 14s unless you want to reach 50km+ which we dont 
The formula you gave is correct, but you didn’t take into account that the bladeangle in a given propeller changes continously from root to tip, depending on the distance from the center of the rotation (local radius). So the “r” in the formula is not just the half of the propeller diameter (at the tips) but the said distance from the center.
In a first approximation (propeller design) the pitch of a propeller is a constant value from root to tip and the local blade angle changes accordingly from root to tip. For some reasons, mostly to prevent cavitation, the 2nd approximation is a slightly diffenrent distribution of the blade angle near root and tip.