Haven’t done testing at high wattages. We’ve focused on cruising efficiency while ensuring their is plenty of thrust for take-off.
Hi. Great thread first of all!
Did you already tried to test a Lily impeller? Red a lot about that and was curios to know if it would be efficient for foils too.
Cheers,
Anton
Anton, Do you have a linky link to the Lily impeller? I’m not familiar with this.
Dan
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Here we go:
the official website of the inventor: Water Technologies — PAX Scientific
http://www.paxwater.com/biomimicry
youtube: https://www.youtube.com/watch?v=9ely-59ChYs
https://www.youtube.com/watch?v=QbskDwYI2dk
some 3D models: Lilly Impeller, free after Jay Harmans drawings by yzorg - Thingiverse
https://grabcad.com/library/lily-style-impeller-1
We also could construct one by our own or make adjustments. I’m curious to see if the impeller is also great in giving thrust as it is in creating vortexes.
Cheers,
Anton
Interesting that the two blade set up created the most thrust with the c80100. Which 3 blade performed the best?
Mantaray, the Solas propeller tested very well. It would require a higher kV motor than I’ve chosen to attain good foiling speed.
I think a higher kV Alien c80100 and the Solas prop may be a very good choice.
This chart below will help match motor speed and prop pitch for the desired. For max efficiency use 85% of max kV x voltage. Also allow about 10 to 15% slip.
Example for my case:
65kV x 44 Volt (average) x .85 = 2,860 rpm
I’m using 10" pitch for now; from the chart then top speed would be about 26 mph with no slip
Add 10% slip and the top expected speed is about 23.5 mph average. A little more when the battery is fresh, a little less as the battery is used up and the voltage starts to drop.
Please note this assumes your drive system has the power to attain the rpm. Too small a motor and you won’t reach the predicted rpm ever.
Dan
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That lily prop has a very organic design, love it !
If that prop would catch your hand, would it 
a) Cut 3 fingers ?
b) Swallow the hand and separate it from the arm ?
c) not bother at all ?
I guess that the protection for such a prop would be enormous ? Or is it dedicated to jet drives ?
Yeah, that thing is big.
A Jet propulsion should be the right way to go. I’m just curious to know if it is possible to gain thrust out of it.
I think I am leaning torwards the C80100 130 kv (http://alienpowersystem.com/shop/brushless-motors/c80100-sensored-outrunner-brushless-motor-130kv-7000w/) and that Solas prop 7.25". Money and time are an issue for my project, so I am trying to figure out the most direct route for my build. Your test data has been very helpful, thanks.
One more thing, I can’t seem to find the input shaft diameter for that Solas prop, any information on that would be very helpful 
Manta, my Solas has a 12mm bore, but it was a bit of a sloppy fit on the 12 mm shaft; yet less than 1/2" diameter.
The c80100 has a 12mm shaft.
How do you plan to waterproof this out-runner? Assuming that you will put it directly into the water.
Max, the plan is to run the motor dry in a pod.
Cooling is a much easier with this setup. Because the power consumption is so low, the motor, esc and batteries do not generate much heat.
Dan
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Winging_it …good testing…Have you got any step files for the Solas propellers?
Morgan. the Solas propeller is manufactured and sold for small outboard motor use. I’m not aware of any step files…seems unlikely the manufacturer would release them.
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Really? Even if you run it at 1000W that should act like a water boiler. Just without any water.
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I’m using passive cooling.The motor will be mounted inside a failrly tight fitting aluminum housing. Heat transfer is a combination of radiant heat transfer and forced convection between the motor and the (well cooled) aluminum housing. This arrangement has already been proven to work well on my first prototype efoil with a much less efficient (meaning more heat) drive.
With the Alien c80100 motor and best prop combination, the flume shows we need 255 watts for 15 lbs. of thrust and 360 watts for 20 lbs. of thrust. The 15 lbs of thrust should provide me with a 15 mph cruise, the 20 lbs more than 20 mph cruise as calculated by the hydrofoil deign tool.
The nice thing about an efficient motor/prop combination is that the benefit of the low power consumption is also reflected in the operation of the esc, wires and batteries as well as the motor. The result is less power wasted as heat everywhere.
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You can do this. Please try it. Take this heavy motor, place it into a pod adding low volume and ventilate air through the windings using part of the motors torque by an integrated fan system. Make sure the air flow is systematic. Try to build lighter than a torqu?do with more peak power. Think about the duct and the motor pod will influence each other. Your flume measurements are a best case, i do not want to critize this. Only to keep it in mind, no gear, everything well cooled and underloaded, prop without duct and motorpod, short time measures without resistance in the waterflow.
I admire your work, but i do not believe the conclusions yet. Anyhow i want to support you with ideas because i feel its a promising way.
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I agree, this flume is best for comparative data. It is a great tool (not perfect) and has helped reduce electric power requirement by a great, great deal. The Leopard motor and prop used in the video below was tested in the flume. Here are the comparative results with the best motor/prop combination so far:
160 kV Leopard motor: 20 lbs. thrust, 1,100 watts and 15 lbs. thrust 770 watts
50 (65 actual) kV Alien: 20 lbs. thrust, 360 watts and 15 lbs. thrust 255 watts
Amazing the difference a well selected motor and prop can make. I’m sure their is still room for further improvement.
The Leopard motor showed no signs of overheating in the lake testing.
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To further clarify the pod setup. The motor will be bolted to an aluminum firewall which will be welded to the aluminum pod. Distance from the motor to the aluminum tube shrouded in water is less than 3 cm. I have all the confidence that the head dissipation will be adequate. With the Leopard motor we were pulling upwards of 50 amps with no heat issues. The new setup, as you can see from the numbers, we are expecting to pull less than 10 amps.
Mike
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If the power requirements prove correct in practical testing that’s a huge improvement on existing setups in terms of battery requirements. I.e same batteries for alot longer runtime, or less battery/cost for same runtime.
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