Author Topic: Diy e-foil!  (Read 15240 times)

PonoBill

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Re: Diy e-foil!
« Reply #15 on: June 28, 2017, 09:03:00 AM »
Interesting graph. I don't think it's completely relevant in this case since what I'm using is more of a shrouded propeller than a jet. I suspect the jet in this graph has an intake flush with the hull and expels the water to drive the boat through a nozzle. There is no screw effect, so at low speed, the jet is hugely inefficient. In the case of the ducted fan jet the impeller is exposed to the water like any propeller. The open question is how efficient is the impeller going to be and what do the straightening vanes do to drag. I don't expect this to be the optimal arrangement by any means. Just cheap, readily available, fairly safe and easy to mount. Here's the page for you northern hemisphere folks.

Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

SUPdad

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Re: Diy e-foil!
« Reply #16 on: July 07, 2017, 04:49:28 PM »
Hi Ponobill,

Hope you keep us posted on how things go. I saw that video and have been thinking about how I might attempt something similar.

The ducted fan is a great idea as a start and I think the impeller will work. Might have to ditch the stators and shroud though. I am 99.99% sure you will need a gearbox...otherwise you're gonna smoke the motor or controller...probably instantly. Make sure you keep the wiring from batteries to controller as short as possible. Extending wires from controller to motor is fine.

surfcowboy

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Re: Diy e-foil!
« Reply #17 on: July 07, 2017, 08:19:17 PM »
Both he and the virus guy on YouTube have this going. I haven't seen gears in either rig. Is that due to the way they are setting up their props/impellers/ I'm not clear on the terms here?

PonoBill

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Re: Diy e-foil!
« Reply #18 on: July 07, 2017, 08:47:00 PM »
So I took the ducted fan and motor , connected it to a 3000 watt controller and a servo tester, then stuck it in a big container of water. Ramped it up slowly until I couldn't hold it much more and measured the wattage using a Lunacycles wattmeter. 620 watts was all I could hold. That's about one horsepower, so no big surprise there.

Clearly I need a reduction gear though--the power was surging. I'm looking at some 6.7 to 1 planetary gear reduction motors. I think a higher reduction would work better, but this is readily available.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

supuk

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Re: Diy e-foil!
« Reply #19 on: July 07, 2017, 10:30:43 PM »
So I took the ducted fan and motor , connected it to a 3000 watt controller and a servo tester, then stuck it in a big container of water. Ramped it up slowly until I couldn't hold it much more and measured the wattage using a Lunacycles wattmeter. 620 watts was all I could hold. That's about one horsepower, so no big surprise there.

Clearly I need a reduction gear though--the power was surging. I'm looking at some 6.7 to 1 planetary gear reduction motors. I think a higher reduction would work better, but this is readily available.

was that a hobbyking edf?

perhaps even a e skateboard maybe a good downer vehicle?
« Last Edit: July 07, 2017, 11:28:38 PM by supuk »

surfcowboy

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Re: Diy e-foil!
« Reply #20 on: July 08, 2017, 01:12:33 AM »
Never mind I see the units are integrated and inline with the motors.

His parts list is in his comments for those who want to dig a bit deeper.

PonoBill

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Re: Diy e-foil!
« Reply #21 on: July 08, 2017, 06:54:20 AM »
So I took the ducted fan and motor , connected it to a 3000 watt controller and a servo tester, then stuck it in a big container of water. Ramped it up slowly until I couldn't hold it much more and measured the wattage using a Lunacycles wattmeter. 620 watts was all I could hold. That's about one horsepower, so no big surprise there.

Clearly I need a reduction gear though--the power was surging. I'm looking at some 6.7 to 1 planetary gear reduction motors. I think a higher reduction would work better, but this is readily available.

was that a hobbyking edf?


Yup. Worked OK, but probably a big Castle Creations one would be a wise investment. I think I can get decent thrust with the ducted fan, but it had a lot of thrust when it first started rotating and I was probably approaching a plateau. I think that's why it was surging. I guess I need te read up a bit on propellors.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

supuk

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Re: Diy e-foil!
« Reply #22 on: July 08, 2017, 07:33:48 AM »
how many blades did it have? was it this one

https://hobbyking.com/en_us/10-blade-alloy-dps-70mm-edf-unit-4s-3000kv-1200watt.html


I'm guessing with all those blades it cant get the water moving fast enough especially held stationary so it just wants to cavertate?

  I have started drawing a few bits up in cad but it really comes down to what props and motor is needed to run it all. it really needs a few calculations from some one who knows so as not to waste to much time.

PonoBill

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Re: Diy e-foil!
« Reply #23 on: July 08, 2017, 09:02:25 PM »
No, I ditched the 70MM one (looked too small) and went with this:
https://hobbyking.com/en_us/edf-ducted-fan-unit-7blade-5inch-127mm.html

I'm looking at these motors:http://neumotors.cartloom.com/shop/item/113046
« Last Edit: July 08, 2017, 09:07:57 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

SUPdad

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Re: Diy e-foil!
« Reply #24 on: July 11, 2017, 05:47:09 PM »
Neu motors are very high quality.  Have you figured out how to seal the output shaft?  Sizing a motor/gearbox/prop/cell count is going to require some experimentation as I don't think there's much data out there. I think I'd try a cheap motor/gearbox until you are certain you can keep the water out and have some baseline data.

Hobby ESCs, at least the good ones, are usually peformance oriented but not particularly robust/forgiving. I don't have any experience with electric skateboard ESCs but might be inclined to try one out as they're cheaper, pretty high current rating and users of them are usually inexperienced with electronics (so assuming they're durable).

SUPdad

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Re: Diy e-foil!
« Reply #25 on: July 11, 2017, 05:53:54 PM »
I think pacificmeister's foil was pulling around 40 amps on 10S or 12S...bad memory. I'm not sure if that's at full throttle or cruise. I guess that's around 1600 watts or so...2hp.

The VESC used in skateboards claims 240 amps momentary and 50 amps continuous on up to 14S...for a mere $100. I have a CC ESC (forget which one) collecting dust that probably cost double that and I wonder if it has the same capabilities.

PonoBill

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Re: Diy e-foil!
« Reply #26 on: July 11, 2017, 06:21:47 PM »
I'm going to stick the whole thing in a carbon tube and fill the tube with silicone grease. a single lip seal on the shaft end. I'll put the esc in the tube and just run the signal and power leads to the battery case. That's the current plan anyway.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

SUPdad

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Re: Diy e-foil!
« Reply #27 on: July 11, 2017, 06:37:54 PM »
I see...single seal and grease.  That should work. I would recommend you keep the ESC as close to the battery as possible, i.e. not in the motor tube. I can't explain why but it's never a good idea to extend the power wires IN to the ESC.

PonoBill

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Re: Diy e-foil!
« Reply #28 on: July 11, 2017, 10:07:00 PM »
I've always found the opposite to be the case. The ESC output is three phase AC. Lots of stuff can happen to AC with longer wires. Battery to ESC is DC and generally a higher voltage/lower current.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

SURFFOILS

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Re: Diy e-foil!
« Reply #29 on: July 17, 2017, 03:47:47 AM »
Once these little e-propulsion units get sorted they'll go on every new surfboard and Sup and paddling will be obsolete. The lineup will be full of little zippers slamming into one another and careering off into the rocks at full speed.
 Laugh ? Wait and see.

 


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