Electric Hydrofoil/E-Foil

Boats, Jet Skis, Kayaks etc., including hovercrafts
toto44   100 mW

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Re: Electric Hydrofoil/E-Foil

Post by toto44 » Jul 20 2017 4:07am

Hello notafraidtotry,

yesterday I started assembly of the jet, just waiting for some sealings. Concerning the wing, how are you planning to use the printed parts? Cover them with carbon, or use them for making molds?

Maybe I start printing them too, but it should make sense to add some grooves to place some reinforcment unidirectional cfk strips. What do you think?

s9tim   10 µW

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Re: Electric Hydrofoil/E-Foil

Post by s9tim » Jul 20 2017 8:14am

Trying to figure out what kind of input gear or ring gear is required to use the torqeedo gear reduction. Has anyone seen the input side yet?

toto44   100 mW

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Re: Electric Hydrofoil/E-Foil

Post by toto44 » Jul 20 2017 8:29am

I found this picture

http://de.boats.com/bootstests/torqeedo ... em-wasser/

scroll down a little bit.

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fechter   100 GW

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Re: Electric Hydrofoil/E-Foil

Post by fechter » Jul 20 2017 9:47am

There seems to be a wide variety of jet drive parts available for RC models. If you Google "40mm jet drive" you will see a bunch. 28mm is very common, but I also saw 40, 50 and 60mm units. Most of them were inexpensive enough that it wouldn't make sense to build your own from scratch. I did not see any rpm ratings on any of them though.
"One test is worth a thousand opinions"

Hiorth   1 W

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Re: Electric Hydrofoil/E-Foil

Post by Hiorth » Jul 20 2017 10:27am

Will soon print duct and propeller (SLS NYLON). And start assembly propulsion unit.

I wanted the duct to reduce chance of getting feets/hands into the propeller. I used a rice speed nozzle with a proven NACA profile (for large vessels)
(http://www.sname.org/HigherLogic/System ... 8bb5440700) think I will go with an AOA of about 5-6 degrees. Should be very efficient on low speeds (before lift) not very efficient over about 15 knots.

Added Stators that holds the duct with some curvature (it should increase the efficiency of the propeller, quote: a poor mans "2" propeller solution). Also designed a propeller with minimum distance to the duct (increase efficiency). Dont have a clue about hydrodynamics, but I have read about many optimizations available to increase Efficiency, which I belive is key to get this to work well.

Do anyone know how to design propellers/ducts? I would really like to get some feedback. I Went with a B-TROOST blade cross section ( http://www.olds.com.au/marine/maximizin ... fficiency/ ), and a pitch + blade outline that I just though looked nice. Propeller Outer diameter : 140mm. Will make a couple of different designs and test in the water.

Just ordered PLE gearbox from neugart. they Will manage 18.000 rpm with sufficient cooling, will also add a temperature sensor that are able to decrease the power if the motor/gearbox overheats.

Batteries are a LOT heavier than fuel in terms of power/weight ratio, so Efficiency is key to get as much time on the water as possible per charge.
Attachments
Skjermbilde 2017-07-20 kl. 17.23.25.png
Rice speed nozzle Duct with propeller overview.
Skjermbilde 2017-07-20 kl. 17.23.25.png (99.8 KiB) Viewed 2335 times
Skjermbilde 2017-07-20 kl. 17.12.08.png
B.Troost profile. the part is made thicker than needed to prevent failure (3d print).
Skjermbilde 2017-07-20 kl. 17.12.08.png (58.91 KiB) Viewed 2335 times
Skjermbilde 2017-07-20 kl. 17.11.24.png
Duct with 6 stators to give an opposite rotation the water than the propeller.
Skjermbilde 2017-07-20 kl. 17.11.24.png (199.74 KiB) Viewed 2335 times

Jezza   10 W

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Re: Electric Hydrofoil/E-Foil

Post by Jezza » Jul 21 2017 3:15am

s9tim wrote:Trying to figure out what kind of input gear or ring gear is required to use the torqeedo gear reduction. Has anyone seen the input side yet?
Page 18, Pos 3 for the 1003 gearbox. It takes a 6mm shaft.

http://www.torqeedospares.co.uk/downloa ... 3_1003.pdf

notafraidtotry   1 mW

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Re: Electric Hydrofoil/E-Foil

Post by notafraidtotry » Jul 21 2017 8:44am

toto44 wrote:Hello notafraidtotry,

yesterday I started assembly of the jet, just waiting for some sealings. Concerning the wing, how are you planning to use the printed parts? Cover them with carbon, or use them for making molds?

Maybe I start printing them too, but it should make sense to add some grooves to place some reinforcment unidirectional cfk strips. What do you think?
Hi Toto,

I am going to laminate the parts in carbon cloth. A friend of mine is a composites engineer and will be supplying some out of date but useable materials next week. He reckons just 1-2 layers will be fine but will take a look at the parts and where we might need more strength. I have now finished printing and have the main parts glued together with CA glue. Build log update,

http://nealedesigns.co.uk/3d-printed-hy ... -laminate/

Its big, photo here,

https://i1.wp.com/nealedesigns.co.uk/wp ... 992502.jpg

I also weighed the parts. It came in at 952g in total so £20 worth of filament (excluding test parts). Boring video of me weighing it here,

https://youtu.be/Sfc6yQjFW0g

I won't be adding any additional carbon spars but now that it is printed I can see just how strong the 3D printed parts can be if you did then re-enforce in the right places. What I would change is to,

1. Make the fuselage thicker towards the rear so you could add a 3D printed hole down the length for a carbon tube.
2. Add a similar hole down the length of the mast for a carbon tube, possibly 2, one at the front and one nearer the back although it does get thin there.
3. Somehow edit the design to make all the pieces key together better. I am hopeless at CAD (just started) but don't think this would be impossible.
4. Edit the mast so you can print the motor mount and full cable run directly into the design

You may still need to laminate the wings as they are thin at the ends but they use very little filament I'd be tempted to try then and see how they hold up. Maybe just re-enforce along the leading edge. If someone can help modify the design of the wing per the above I am happy to try and print a V2.

So, I have about a week to wait before I get the resin and carbon cloth. I'll lay it up wet without a vacuum pump, don't think its needed. Then its on to working out the drive. The friend Nick I am building it with is collecting a couple of old surfboards that we will mount the foil to. No clue what they are like yet.

npagazani   10 µW

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Re: Electric Hydrofoil/E-Foil

Post by npagazani » Jul 21 2017 9:32am

fechter wrote:There seems to be a wide variety of jet drive parts available for RC models. If you Google "40mm jet drive" you will see a bunch. 28mm is very common, but I also saw 40, 50 and 60mm units. Most of them were inexpensive enough that it wouldn't make sense to build your own from scratch. I did not see any rpm ratings on any of them though.
If you search a bit harder you’ll see the lampuga jet boards out of Germany uses the 64mm jet from MHZ. They give some details, like the thrust, RPM, and the motor to use. The Lampuga site shows you the horsepower. Not cheap, but proven. Anyways, you can put it all together and back calculate the nozzle diameter and impeller pitch.
Before MHZ updated their site a couple months back, they actually had a link to the lampuga youtube video directly in their product page for the 64mm jet.

notafraidtotry   1 mW

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Re: Electric Hydrofoil/E-Foil

Post by notafraidtotry » Jul 21 2017 11:42am

Very non scientific look at some of the 3D printed test pieces I printed and different infills. Cubic at 20% is very strong. The fuselage tail gets very thin though so could not be used without laminating in carbon unless the design is changed.



Kudos to the designer of the foil, Prof. Michele Fiorentino from Bari Italy. I got in touch with him via GrabCad where he posted his design. He spent hours on the design and modelling and proved that it works for kitesurfing. Hopefully it will work just as well for the electric surfboard.

npagazani   10 µW

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Re: Electric Hydrofoil/E-Foil

Post by npagazani » Jul 21 2017 12:04pm

notafraidtotry wrote:Very non scientific look at some of the 3D printed test pieces I printed and different infills. Cubic at 20% is very strong. The fuselage tail gets very thin though so could not be used without laminating in carbon unless the design is changed.



Kudos to the designer of the foil, Prof. Michele Fiorentino from Bari Italy. I got in touch with him via GrabCad where he posted his design. He spent hours on the design and modelling and proved that it works for kitesurfing. Hopefully it will work just as well for the electric surfboard.
@notafraidtotry, nice work you're doing, watching closely to see how you get on. I'm familiar with that foil 3D model and have used it myself for mock-ups. You might want to consider a foil/front wing from a foil surf board or SUP board. Kite foils generally have lower lift since the kite tends to do some of the lifting. Cheers.

notafraidtotry   1 mW

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Re: Electric Hydrofoil/E-Foil

Post by notafraidtotry » Jul 21 2017 1:25pm

I have been doing some digging into the use of brushless out runners. The Open ROV teams use these extensively for their thrusters. Many operate them without any modifications and just replace as needed but others go to a little more effort and use potting compounds to help prevent corrosion. The motors work fine in fresh water or salt water but the bearings will seemingly corrode first and other components over time. The windings themselves are insulated of course but can gradually get damaged by silt etc.

Good thread on their forum here,

http://www.homebuiltrovs.com/rovforum/v ... 2&start=20

So, I think it is worth a shot to test out the 3D Printed Hydrofoil using a relatively stock out-runner. It would require no gearbox and no complicated enclosure.

Alien Power systems do some nice low kV out-runners. It would just require finding the right prop. So at the moment the component list I have in my head would be,

60kV out-Runner
http://alienpowersystem.com/shop/brushl ... 0kv-3200w/

Banggood Transmitter & Receiver
https://www.banggood.com/2_4GHz-Radio-R ... mds=search

Red Brick 200A ESC
https://www.banggood.com/Red-Brick-200A ... mds=search

UBEC
https://www.banggood.com/DC-DC-Converte ... mds=search

2 x 5S 5000mah batteries (connected in series)
https://www.banggood.com/ZOP-Power-18_5 ... mds=search

XT60 Series Connector
https://www.banggood.com/XT60-2-string- ... mds=search

Total cost around £200

More than enough power to get foiling (3200w is the peak power) will need less once up. That will give around 2200 RPM running at 10S. I am still hopeful that the 80kV in-runner that Alien Power Systems is releasing soon will be a better solution but suspect it will come with a hefty price tag.

I'll definitely be risking the out-runner with this approach but its not too expensive an experiment. I will need to work out the best prop to use though so suggestions welcome. It will be 2-3 weeks before I can test as still need to laminate the foil and wait for parts.

notafraidtotry   1 mW

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Re: Electric Hydrofoil/E-Foil

Post by notafraidtotry » Jul 21 2017 1:27pm

npagazani wrote:
notafraidtotry wrote:Very non scientific look at some of the 3D printed test pieces I printed and different infills. Cubic at 20% is very strong. The fuselage tail gets very thin though so could not be used without laminating in carbon unless the design is changed.



Kudos to the designer of the foil, Prof. Michele Fiorentino from Bari Italy. I got in touch with him via GrabCad where he posted his design. He spent hours on the design and modelling and proved that it works for kitesurfing. Hopefully it will work just as well for the electric surfboard.
@notafraidtotry, nice work you're doing, watching closely to see how you get on. I'm familiar with that foil 3D model and have used it myself for mock-ups. You might want to consider a foil/front wing from a foil surf board or SUP board. Kite foils generally have lower lift since the kite tends to do some of the lifting. Cheers.
Thanks, I might print another front wing so I can test both. Do you have any suggestions or links for front wings? I'll likely print and laminate as I am doing for this one. If I make it up now I can ensure they are interchangeable.

npagazani   10 µW

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Re: Electric Hydrofoil/E-Foil

Post by npagazani » Jul 21 2017 3:04pm

notafraidtotry wrote:
npagazani wrote:
notafraidtotry wrote:Very non scientific look at some of the 3D printed test pieces I printed and different infills. Cubic at 20% is very strong. The fuselage tail gets very thin though so could not be used without laminating in carbon unless the design is changed.



Kudos to the designer of the foil, Prof. Michele Fiorentino from Bari Italy. I got in touch with him via GrabCad where he posted his design. He spent hours on the design and modelling and proved that it works for kitesurfing. Hopefully it will work just as well for the electric surfboard.
@notafraidtotry, nice work you're doing, watching closely to see how you get on. I'm familiar with that foil 3D model and have used it myself for mock-ups. You might want to consider a foil/front wing from a foil surf board or SUP board. Kite foils generally have lower lift since the kite tends to do some of the lifting. Cheers.
Thanks, I might print another front wing so I can test both. Do you have any suggestions or links for front wings? I'll likely print and laminate as I am doing for this one. If I make it up now I can ensure they are interchangeable.
At the moment I don't have another 3D model, sorry. I've got a contact with a foil manufacturer that might be willing to fund my own jet foil build, waiting on his model, but I've agreed not to share it.

npagazani   10 µW

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Re: Electric Hydrofoil/E-Foil

Post by npagazani » Jul 21 2017 3:21pm

notafraidtotry wrote:I have been doing some digging into the use of brushless out runners. The Open ROV teams use these extensively for their thrusters. Many operate them without any modifications and just replace as needed but others go to a little more effort and use potting compounds to help prevent corrosion. The motors work fine in fresh water or salt water but the bearings will seemingly corrode first and other components over time. The windings themselves are insulated of course but can gradually get damaged by silt etc.

Good thread on their forum here,

http://www.homebuiltrovs.com/rovforum/v ... 2&start=20

So, I think it is worth a shot to test out the 3D Printed Hydrofoil using a relatively stock out-runner. It would require no gearbox and no complicated enclosure.

Alien Power systems do some nice low kV out-runners. It would just require finding the right prop. So at the moment the component list I have in my head would be,

60kV out-Runner
http://alienpowersystem.com/shop/brushl ... 0kv-3200w/

Banggood Transmitter & Receiver
https://www.banggood.com/2_4GHz-Radio-R ... mds=search

Red Brick 200A ESC
https://www.banggood.com/Red-Brick-200A ... mds=search

UBEC
https://www.banggood.com/DC-DC-Converte ... mds=search

2 x 5S 5000mah batteries (connected in series)
https://www.banggood.com/ZOP-Power-18_5 ... mds=search

XT60 Series Connector
https://www.banggood.com/XT60-2-string- ... mds=search

Total cost around £200

More than enough power to get foiling (3200w is the peak power) will need less once up. That will give around 2200 RPM running at 10S. I am still hopeful that the 80kV in-runner that Alien Power Systems is releasing soon will be a better solution but suspect it will come with a hefty price tag.

I'll definitely be risking the out-runner with this approach but its not too expensive an experiment. I will need to work out the best prop to use though so suggestions welcome. It will be 2-3 weeks before I can test as still need to laminate the foil and wait for parts.
For your propeller, will the torqeedo prop work? Maybe try pacifimeister (youtube user, also on this thread I think but can't remember his username at the moment), he 3D printed his I believe. (He probably wouldn't mind sharing it since he can only really use it for his personal use. Nick Leason at lift foils has exclusive use of the US patent for the jet foil, as well as the patent owner but he's not developing anything at the moment).

In terms of the submerged motor I'm interested to see how that works. I've some other guys online try and they seemed to have issues with motor sync, but it wasn't clear if it was not enough power for the resistance of the prop or the fact that it was submerged. In theory it should work, as I've seen them run submerged without load no problem.

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Re: Electric Hydrofoil/E-Foil

Post by nanni » Jul 21 2017 3:27pm

notafraidtotry wrote:Red Brick 200A ESC
https://www.banggood.com/Red-Brick-200A ... mds=search
It's only 2-7s, you need a hv esc, something like this https://szfvt.en.alibaba.com/product/60 ... 196183VHPC or this https://szfvt.en.alibaba.com/product/60 ... e1e4TNjTJD or Bruno's esc http://alienpowersystem.com/shop/esc/al ... et-esc-hv/
For the bearings you can look for "ceramic bearings" no rust and no probem in salt water. https://www.banggood.com/it/6000-Full-C ... mds=search . Bruno's 6374 has a 10mm shaft, maybe they are of the same size.

Gege2000   10 mW

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Re: Electric Hydrofoil/E-Foil

Post by Gege2000 » Jul 21 2017 10:42pm

npagazani wrote:Maybe try pacifimeister (youtube user, also on this thread I think but can't remember his username at the moment), he 3D printed his I believe. (He probably wouldn't mind sharing it since he can only really use it for his personal use.
Hello, if you see his vid number 12, the working propeller is not the 3D printed version. It's a small orange propeller, something like that : http://thumbs3.ebaystatic.com/d/l225/m/ ... fsVifQ.jpg .

Big ESCs and small kV are hard to find. What do you think to use two aligned motors with 2x the kV, and 2 ESCs, each motor under 5-6S :?:

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Bazaki   10 kW

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Re: Electric Hydrofoil/E-Foil

Post by Bazaki » Jul 22 2017 3:00am

In the past i have used a turnigy c80100 rewind to 45kv and had sync issues. Also used a revolt 10 motor i believe 45kv with ceramic bearings and epoxied stator. Also sync issues with different controllers. A direct drive under water was not so easy. Torqeedo proofed itself and uses a gearbox. Why would they do that? The outrunner can run high rpm in the sweet spot for efficiency. But maybe with hall sensors a direct drive can be done.

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Re: Electric Hydrofoil/E-Foil

Post by Hiorth » Jul 24 2017 4:35am

Just posted some illustrations of our 3d models here, will continue to post updates as we go forth. https://www.facebook.com/media/set/?set ... 2e97c1f9fb

Cheers

notafraidtotry   1 mW

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Re: Electric Hydrofoil/E-Foil

Post by notafraidtotry » Jul 24 2017 6:00am

Hiorth wrote:Just posted some illustrations of our 3d models here, will continue to post updates as we go forth. https://www.facebook.com/media/set/?set ... 2e97c1f9fb

Cheers
They look great.

We are still working on various drive options. I have updated the parts list based on feedback here but the plan will be to ensure we can test different drives but keep the same electronics, batteries etc.

The OpenROV teams use bog standard out-runners sprayed with silicon spray before each dive and rinsed with fresh water. Sync issues are a possibility but seem to be when you use too large a prop and the ESC expects to see higher speeds. I'm still tempted to try this approach out but guess the in runner and gearbox route will be the best and is of course tested. The gearboxes just seem to be very expensive.

I have even started looking at the large professional cordless drills. My hope is still to find something that already exists that can be re-purposed. You can get used 36V cordless drills without batteries for under £50. The Dewalt DC900 for example is brushless (motor may or may not be usable) but the planetary gearbox is all metal. Output speed is 1,400 RPM with the motor running at around 22,000 RPM so getting into the right ballpark. These things retail at well over £500 new so they are well made. The clutch can be locked out although might be useful.

Anyone looked at using them?

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dirty_d   10 kW

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Re: Electric Hydrofoil/E-Foil

Post by dirty_d » Jul 24 2017 1:56pm

Is this one of you? https://www.youtube.com/watch?v=D-zdHYI_ZkI

I have that same motor just laying around unused, hmm...

notafraidtotry   1 mW

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Re: Electric Hydrofoil/E-Foil

Post by notafraidtotry » Jul 24 2017 3:05pm

dirty_d wrote:Is this one of you? https://www.youtube.com/watch?v=D-zdHYI_ZkI

I have that same motor just laying around unused, hmm...
Thanks for sharing. On his other video it shows he can't get the motor to turn under water as it immediately goes out of sync. The prop is way too big and would need to be already spinning to have any chance of running. It is the same issue electric skateboard users have. They can't start from stationary but have to kick off first then apply power.

A smaller prop I am confident will work. The small APC propeller the Citysurfer used would have a lot less resistance and could probably avoid the sync issue. Definitely makes me wonder if he is running without a gearbox.

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Re: Electric Hydrofoil/E-Foil

Post by Hiorth » Jul 24 2017 4:11pm

A good explanation I found on another forum about the difference in efficiency with a small prop with high rpm vs large prop with low rpm. Its for an aircraft, but the theory is more or less the same. https://www.rcgroups.com/forums/showthr ... p-high-rpm

quote:
Regarding the small fast prop vs. the large slow:

There are two fundamental laws regarding impulse and energy that -when understood- clear up things a lot.

First:
The thrust from the propeller is achieved by taking an amount of air and thrusting it backwards. This propels you forward.
The thrust is determined by the mass flow multiplied by its increase in velocity:

F = m * V.

Second:
The power required to attain the propulsion is given by the formula:
P = ½ * m * V^2


F = Newton
m = mass flow (kg per second)
V = increase in velocity (meters per second)
P = power (Watts = volts * ampere)



Now comes the golde clue:

To achieve a certain thrust you can either choose a little fast prop or large slow prop.
You get the same thrust as long as the product of m and V is the same.

But the power needed to drive the system is not independent of the two measures:
If you choose a little propeller the mass flow reduces and the velocity must increase likewise.
This means that if the mass flow is reduced by a factor of two - the V^2 terms is quadrupled.
This means that the power needed from the motor and battery is doubled!!!!!!

The power is inversely proporional to the size of the propeller.

I recently noticed this when a friend of mine was boosting his little EDF. He kept increasing the number of cells onboard but instead of getting vertical performance his plane got heavier and showed less and less performance. The way to go had in hs place been to choose a larger fan as this would have decreased the V and therefore power consumption.

Regards
Max

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parabellum   10 MW

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Re: Electric Hydrofoil/E-Foil

Post by parabellum » Jul 24 2017 7:47pm

Just ordered 1 of this things. Can not stop thinking about the potential low hanging fruits we are overseeng. By specs it is 1160W motor, but we all love that smell of plasma consumed motors. Right? :lol:
Image
http://www.ebay.com/itm/86LBS-Thrust-El ... 2749.l2649

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Re: Electric Hydrofoil/E-Foil

Post by toto44 » Jul 25 2017 3:57am

The pushing force is not bad, but it will not create speed. You can already see from the pitch of the prop.

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dirty_d   10 kW

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Re: Electric Hydrofoil/E-Foil

Post by dirty_d » Jul 25 2017 8:10am

notafraidtotry wrote:
dirty_d wrote:Is this one of you? https://www.youtube.com/watch?v=D-zdHYI_ZkI

I have that same motor just laying around unused, hmm...
Thanks for sharing. On his other video it shows he can't get the motor to turn under water as it immediately goes out of sync. The prop is way too big and would need to be already spinning to have any chance of running. It is the same issue electric skateboard users have. They can't start from stationary but have to kick off first then apply power.

A smaller prop I am confident will work. The small APC propeller the Citysurfer used would have a lot less resistance and could probably avoid the sync issue. Definitely makes me wonder if he is running without a gearbox.
I think if you really wanted to try this with the torqeedo prop, you could by flashing a custom firmware to the ESC. It's definitely possible to run a motor sensorless like that. The ESC by default just isn't expecting the motor to accelerate so slowly.

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