Electric Hydrofoil/E-Foil

Boats, Jet Skis, Kayaks etc., including hovercrafts
LogicalDIYBuilder
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Re: Electric Hydrofoil/E-Foil

Post by LogicalDIYBuilder » Aug 08, 2017 6:56 am

Jezza wrote:
Hiorth wrote: Did it work with O-rings and screws? I will make this on my next version, but I belive the O-ring grooves should be machined in aluminium (not 3d printed) to ensure a good seal. The O-ring should be compressed about 30% to obtain a good seal, see drawing below of tube edge and o-ring groove. Have discussed this matter with a couple of very clever oil engineers, that works with this type of seals daily. If you need to be extra sure you can add in two rings, and bigger is better! In our case 2-3mm O-rings is ideal.
Cheers
I printed some test parts (without screws) and lowered the unit 1.5m under water. Then left it for 1hr 30mins and pulled it out. Didn't take a huge amount of water, but enough to cause trouble. But I agree with the not using seals on 3D printed parts. I will hopefully be cutting the new parts on the lathe this evening and will then test the seals again.
Yes, I did a 48 hour water test through warm water then cold as the motor will heat the air and contract (suck in cold water). Water test was a success but im still waterproofing my motor and bearings this week to protect bearings from moisture. You can youtube how to waterproof your motor bearings and other bearings (just thick marine grease on both sides will save the bearings dramatically.

I would be more concerned with the high torque on the 3D parts glued into tubing as things heat/cool causing expansion and breaking seams which is why I didnt glue mine but threaded into aluminum with o-rimgs
I'm an entrepreneur, stock & commodity trader, landlord, and self-storage business owner.
Built & Building: DIY Electric Hydrofoil Board http://www.diy-electric-hydrofoil.com/, Electric Dirt Bike, Self-Storage Portable Delivery System, High Volume Sand Dredge, Tazer/Stungun, Barge Boat, Air Planes

waterfox
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Re: Electric Hydrofoil/E-Foil

Post by waterfox » Aug 08, 2017 7:40 am

Hiorth wrote: I belive the O-ring grooves should be machined in aluminium (not 3d printed) to ensure a good seal. The O-ring should be compressed about 30% to obtain a good seal,
Cheers
Have a look at the Parker O-Ring handbook. https://www.parker.com/literature/ORD%2 ... ndbook.pdf
Probably page 4-5 is what you are looking for.

I'm using 3X Dash 226 on my next design.

I'm just looking for someone to machine the aluminum for me..
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Jezza
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Re: Electric Hydrofoil/E-Foil

Post by Jezza » Aug 08, 2017 8:30 am

waterfox wrote:
Hiorth wrote: I belive the O-ring grooves should be machined in aluminium (not 3d printed) to ensure a good seal. The O-ring should be compressed about 30% to obtain a good seal,
Cheers
Have a look at the Parker O-Ring handbook. https://www.parker.com/literature/ORD%2 ... ndbook.pdf
Probably page 4-5 is what you are looking for.

I'm using 3X Dash 226 on my next design.

I'm just looking for someone to machine the aluminum for me..
I used a seal calculator where you type in the dimensions and o-ring material and then then it says whether its in spec or not.

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Re: Electric Hydrofoil/E-Foil

Post by beonwater » Aug 08, 2017 6:03 pm

lwienhues wrote:
Hiorth wrote: Will make my Onshape document (contains all 3d files etc) Public so that anyone can copy download and edit parts. Will also upload to grabcad, but will wait until I know it works (hopefully this weekend).
This would be awesome, thanks in advance!
I am especially interested in the prop and duct if that turns out to work well. Why did you print the duct a second time?

Oh and hi everybody! We're a group from southern Germany going down the Pacificmeister route with the difference of a Neugart PLE40 1:5 and a Sroka foil. Printing in PETG. I'll let you know how things work out.
We've been reading along for quite some time now...

Cheers,
Lukas
Can you tell me how you use the sroka foil. I have the Sroka v2 and thinking of using that or build my own mast. Have you drilled a hole on the mast mount for the motor wires?
Do you think that the sroka foil will need a little more speed than the Liquid Force foil that pacificmeister use? Sroka is more medium aspect so it would be interesting to see how it will behave.
Will you use the sroka board or use another one? I think the Probox that they´re using is a seems harder to use on other boards if you compare with a platemount.

I´m also ordered a Neugart PLE40 5:1 to use with my TPPower 5690 inrunner with 290kv and 15s.

lwienhues
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Re: Electric Hydrofoil/E-Foil

Post by lwienhues » Aug 09, 2017 2:23 am

beonwater wrote: Can you tell me how you use the sroka foil. I have the Sroka v2 and thinking of using that or build my own mast. Have you drilled a hole on the mast mount for the motor wires?
Do you think that the sroka foil will need a little more speed than the Liquid Force foil that pacificmeister use? Sroka is more medium aspect so it would be interesting to see how it will behave.
Will you use the sroka board or use another one? I think the Probox that they´re using is a seems harder to use on other boards if you compare with a platemount.

I´m also ordered a Neugart PLE40 5:1 to use with my TPPower 5690 inrunner with 290kv and 15s.
For the moment I'm not modifying the board or mast at all since I want a proof of concept first. Im planning to lead the cables outside of the mast, maybe with printed tubing for less drag.

Regarding the speed the Sroka foil needs I am also not sure. While kiting it comes out of the water really early, but I have no direct comparison to for example the Liquid Force foil. Online reviews describe it as "foiling at relatively low speeds" ( https://www.iksurfmag.com/reviews/board ... foil-2015/ )
So in summary I think it's worth a shot. I'll let you know, but it'll take a few weeks.

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Re: Electric Hydrofoil/E-Foil

Post by Jezza » Aug 09, 2017 4:24 am

Frustration... I spent 2 and a half hours last night trying to fight my way through aluminium bar on a mini lathe in order to get my spacers done for the motor/gearbox. After that time I was left with almost the same aluminium bar! Time to find a large lathe or someone that can machine the parts for me.

beonwater
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Re: Electric Hydrofoil/E-Foil

Post by beonwater » Aug 09, 2017 6:13 am

What type/size of cables do you using from the ESC to the motor? I bought 10 AWG but when I received the TPPower motor I notice that they are much smaller. Could it be silver that reduce the need for wider diameter? According to the spec it could take 109 amps.

LogicalDIYBuilder
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Re: Electric Hydrofoil/E-Foil

Post by LogicalDIYBuilder » Aug 09, 2017 8:34 am

I took my parts to local shop they pumped out the parts in less than an hour for my aluminum tube.

I used 8awg wire from motor to ESC, better safe than sorry... I'm not a fan of electrical fires or melting rubber near me :)

Keep in mind the shorter the wires the more juice you can put through them. once you get over 1m wire size must get larger, and 2m much thicker wire.... for 109amp if that what you are running you're going to need substantial wires to be in the safe zone.
I'm an entrepreneur, stock & commodity trader, landlord, and self-storage business owner.
Built & Building: DIY Electric Hydrofoil Board http://www.diy-electric-hydrofoil.com/, Electric Dirt Bike, Self-Storage Portable Delivery System, High Volume Sand Dredge, Tazer/Stungun, Barge Boat, Air Planes

NolaDoogie
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Re: Electric Hydrofoil/E-Foil

Post by NolaDoogie » Aug 09, 2017 11:52 am

For those using the SSS motors...... The mounting holes for this motor are in the front or said another way, on the same side as the output shaft. How are you guys mounting the motor to the mast? The propeller will make loads of torque, trying to spin the whole assembly itself. Am I wrong to assume this load will need to be transferred through the aluminum tube back to the front of the assembly where it attaches to the mast? If so, are you using adhesive to attach the aluminum tube? Bolts?

SmokeThroughWires
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Re: Electric Hydrofoil/E-Foil

Post by SmokeThroughWires » Aug 09, 2017 12:11 pm

Howdy folks,

I'm "notafraidtotry's" partner in crime (also on this forum) for an Electric Hydrofoil Board project.
We appear to have been through the same research pains as many others. The biggest hurdle we are coming up against is the cost of a decent gearbox to reduce RPM down to the right level for a ducted prop (as low KV motors seem to be pretty none existent). Sadly our budget is limited. We're getting very bored of searching for products online!

My latest train of thought, in an attempt to come up with a workable, affordable solution is this:

Motor housed in the board with a drive shaft down through the foil mast. A Right angle (1:1) gearbox at the bottom to direct the drive shaft out backwards for prop (ducted), or perhaps even a "T" gearbox with props front and rear of the foil mast (counter rotating).
As for the motor in the board... (this is the radical bit).... an eBike Hub motor used as a belt drive onto a smaller gear on the top of the drive shaft.........
Sketch -eFoil.jpg
Excuse the dodgy sketch - I had run out of fag-packets.

My thoughts: eBike hubs are cheap and in abundance. They tend to be very low KV, fairly high power (have been looking at 3000w+ options) and robust. Designing the rest of the system would also be very easy, as many of them come with ESC's etc. Provided I can get the cooling right (which I have a few ideas for) I'm struggling to see reasons this wouldn't work.

I'd greatly appreciate if people could please point out the flaws in my corner-cutting design!

SmokeThroughWires

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Re: Electric Hydrofoil/E-Foil

Post by dirkdiggler » Aug 09, 2017 3:34 pm

Check ebay for Neugart gear reducers. I've seen a bunch at decent pricing. Not always the right reduction or size, but you might find some at the right price.

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Re: Electric Hydrofoil/E-Foil

Post by Hiorth » Aug 09, 2017 5:18 pm

NolaDoogie wrote:For those using the SSS motors...... The mounting holes for this motor are in the front or said another way, on the same side as the output shaft. How are you guys mounting the motor to the mast? The propeller will make loads of torque, trying to spin the whole assembly itself. Am I wrong to assume this load will need to be transferred through the aluminum tube back to the front of the assembly where it attaches to the mast? If so, are you using adhesive to attach the aluminum tube? Bolts?
You are correct. The torque is transferred from the motor through the gearbox and into the aluminium tube. I will use epoxy, but there are many other ways that will work!

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Re: Electric Hydrofoil/E-Foil

Post by Hiorth » Aug 09, 2017 5:30 pm

SmokeThroughWires wrote:Howdy folks,

I'm "notafraidtotry's" partner in crime (also on this forum) for an Electric Hydrofoil Board project.
We appear to have been through the same research pains as many others. The biggest hurdle we are coming up against is the cost of a decent gearbox to reduce RPM down to the right level for a ducted prop (as low KV motors seem to be pretty none existent). Sadly our budget is limited. We're getting very bored of searching for products online!

My latest train of thought, in an attempt to come up with a workable, affordable solution is this:

Motor housed in the board with a drive shaft down through the foil mast. A Right angle (1:1) gearbox at the bottom to direct the drive shaft out backwards for prop (ducted), or perhaps even a "T" gearbox with props front and rear of the foil mast (counter rotating).
As for the motor in the board... (this is the radical bit).... an eBike Hub motor used as a belt drive onto a smaller gear on the top of the drive shaft.........
Sketch -eFoil.jpg
Excuse the dodgy sketch - I had run out of fag-packets.

My thoughts: eBike hubs are cheap and in abundance. They tend to be very low KV, fairly high power (have been looking at 3000w+ options) and robust. Designing the rest of the system would also be very easy, as many of them come with ESC's etc. Provided I can get the cooling right (which I have a few ideas for) I'm struggling to see reasons this wouldn't work.

I'd greatly appreciate if people could please point out the flaws in my corner-cutting design!

SmokeThroughWires
I´m quite sure your setup will work... but I´m not sure it will end up cheaper than with a gear reduction, you need a specially made foil mast with an 90angle gear incorporated and additional cooling. One flaw I can think of is that the Hub motors with decent power is pretty heavy, you will have additional weight as the motor is designet to be a bike HUB as well as a motor, which I guess is not Ideal to have inside the Board that is supposed to be lifted from the water (there will be a bit more noise as well ;).

Why not couple the hub motor directly to the axle, would save some time. Not high enough RPM maybe?

SmokeThroughWires
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Re: Electric Hydrofoil/E-Foil

Post by SmokeThroughWires » Aug 10, 2017 3:08 am

Hiorth wrote:
SmokeThroughWires wrote:Howdy folks,

I'm "notafraidtotry's" partner in crime (also on this forum) for an Electric Hydrofoil Board project.
We appear to have been through the same research pains as many others. The biggest hurdle we are coming up against is the cost of a decent gearbox to reduce RPM down to the right level for a ducted prop (as low KV motors seem to be pretty none existent). Sadly our budget is limited. We're getting very bored of searching for products online!

My latest train of thought, in an attempt to come up with a workable, affordable solution is this:

Motor housed in the board with a drive shaft down through the foil mast. A Right angle (1:1) gearbox at the bottom to direct the drive shaft out backwards for prop (ducted), or perhaps even a "T" gearbox with props front and rear of the foil mast (counter rotating).
As for the motor in the board... (this is the radical bit).... an eBike Hub motor used as a belt drive onto a smaller gear on the top of the drive shaft.........
The attachment Sketch -eFoil.jpg is no longer available
Excuse the dodgy sketch - I had run out of fag-packets.

My thoughts: eBike hubs are cheap and in abundance. They tend to be very low KV, fairly high power (have been looking at 3000w+ options) and robust. Designing the rest of the system would also be very easy, as many of them come with ESC's etc. Provided I can get the cooling right (which I have a few ideas for) I'm struggling to see reasons this wouldn't work.

I'd greatly appreciate if people could please point out the flaws in my corner-cutting design!

SmokeThroughWires
I´m quite sure your setup will work... but I´m not sure it will end up cheaper than with a gear reduction, you need a specially made foil mast with an 90angle gear incorporated and additional cooling. One flaw I can think of is that the Hub motors with decent power is pretty heavy, you will have additional weight as the motor is designet to be a bike HUB as well as a motor, which I guess is not Ideal to have inside the Board that is supposed to be lifted from the water (there will be a bit more noise as well ;).

Why not couple the hub motor directly to the axle, would save some time. Not high enough RPM maybe?
Thanks Hiorth - foil mast not an issue. Can 3D print and laminate in carbon - giving us flexibility over design (and cheap). I'm also not too bothered about a little extra weight..... I'll just have to lose a few kg's in body fat to compensate :) Motor directly on axle wouldn't be high enough RPM as the eBike hub motors are very low KV/RPM..... however your message did lead me to the next iteration (thank you).........
eBike motor design2.jpg
eBike motor design2.jpg (12.25 KiB) Viewed 937 times
This system would also allow for a detachable foil which would be great.
The one main disadvantage is the thickness of the motors - may have to use a slightly thicker board, but that wouldn't be the end of the world.
Attachments
eBike motor design2.jpg
(207.28 KiB) Downloaded 8 times

markula78
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Re: Electric Hydrofoil/E-Foil

Post by markula78 » Aug 10, 2017 4:15 am

SmokeThroughWires wrote:
Hiorth wrote:
SmokeThroughWires wrote:Howdy folks,

I'm "notafraidtotry's" partner in crime (also on this forum) for an Electric Hydrofoil Board project.
We appear to have been through the same research pains as many others. The biggest hurdle we are coming up against is the cost of a decent gearbox to reduce RPM down to the right level for a ducted prop (as low KV motors seem to be pretty none existent). Sadly our budget is limited. We're getting very bored of searching for products online!

My latest train of thought, in an attempt to come up with a workable, affordable solution is this:

Motor housed in the board with a drive shaft down through the foil mast. A Right angle (1:1) gearbox at the bottom to direct the drive shaft out backwards for prop (ducted), or perhaps even a "T" gearbox with props front and rear of the foil mast (counter rotating).
As for the motor in the board... (this is the radical bit).... an eBike Hub motor used as a belt drive onto a smaller gear on the top of the drive shaft.........
Sketch -eFoil.jpg
Excuse the dodgy sketch - I had run out of fag-packets.

My thoughts: eBike hubs are cheap and in abundance. They tend to be very low KV, fairly high power (have been looking at 3000w+ options) and robust. Designing the rest of the system would also be very easy, as many of them come with ESC's etc. Provided I can get the cooling right (which I have a few ideas for) I'm struggling to see reasons this wouldn't work.

I'd greatly appreciate if people could please point out the flaws in my corner-cutting design!

SmokeThroughWires
I´m quite sure your setup will work... but I´m not sure it will end up cheaper than with a gear reduction, you need a specially made foil mast with an 90angle gear incorporated and additional cooling. One flaw I can think of is that the Hub motors with decent power is pretty heavy, you will have additional weight as the motor is designet to be a bike HUB as well as a motor, which I guess is not Ideal to have inside the Board that is supposed to be lifted from the water (there will be a bit more noise as well ;).

Why not couple the hub motor directly to the axle, would save some time. Not high enough RPM maybe?
Thanks Hiorth - foil mast not an issue. Can 3D print and laminate in carbon - giving us flexibility over design (and cheap). I'm also not too bothered about a little extra weight..... I'll just have to lose a few kg's in body fat to compensate :) Motor directly on axle wouldn't be high enough RPM as the eBike hub motors are very low KV/RPM..... however your message did lead me to the next iteration (thank you).........
eBike motor design2.jpg
This system would also allow for a detachable foil which would be great.
The one main disadvantage is the thickness of the motors - may have to use a slightly thicker board, but that wouldn't be the end of the world.
A E-bike hub motor is spinning at about 500RPM 26" wheel 1000W 60 km/h. If you remove the planetary gearbox is about 1:5 you will find the motor is spinning at 2500-3000 that is perfect for direct drive. But in a 90 angle gear have about 85% efficiency vs 1 step planetary gear 95%+.

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Re: Electric Hydrofoil/E-Foil

Post by Jezza » Aug 10, 2017 4:25 am

SmokeThroughWires wrote:Howdy folks,
As for the motor in the board... (this is the radical bit).... an eBike Hub motor used as a belt drive onto a smaller gear on the top of the drive shaft.........
Sketch -eFoil.jpg
SmokeThroughWires
With a foil, the more weight you shift further from the foil makes it harder to control. Having extra weight in the board is very different from having extra body weight as you have less control over it.
The advantage of having the extra weight down at the foil works much like a yacht centre board/keel ie. the lower the weight, the more stable.
I don't think what you want to do is impossible, I just don't think it is the optimal solution.

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Re: Electric Hydrofoil/E-Foil

Post by parabellum » Aug 10, 2017 7:31 am

SmokeThroughWires wrote:Thanks Hiorth - foil mast not an issue. Can 3D print and laminate in carbon - giving us flexibility over design (and cheap). I'm also not too bothered about a little extra weight..... I'll just have to lose a few kg's in body fat to compensate :) Motor directly on axle wouldn't be high enough RPM as the eBike hub motors are very low KV/RPM..... however your message did lead me to the next iteration (thank you).........
1)It can be difficult to deal with centrifugal forces of wide D hub in this position.
2) Sure, 1KW DD hub could make sustainable 4KW by raising RPM (with .35 lamination and staying below high iron loses) and bursts of up to 10KW IN, until it reaches its saturation point, but again you need good airflow on the rotor shell to cool it. What is your plan for that?

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Re: Electric Hydrofoil/E-Foil

Post by FROGMANGEEK » Aug 10, 2017 7:46 am

Just to share an idea for those who want to make their own hydrofoil. Why not using already made ppe wing :
-already cut and ready for laminate
-PPE is soft so you can give the wing the diedral you want
-airfoil used on these wings are for gliding /soaring ,these airfoil could be good to have early glide.

Here is a link :

https://hobbyking.com/fr_fr/hobbykingr- ... m-arf.html


For the mast and stabiliser it could be great idea to use depron foam and hollow aluminium spar, doing like this :
https://www.google.fr/search?biw=1920&b ... E2PsNKlg2M:

Once done u just have to laminate ;)
Regards,

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Re: Electric Hydrofoil/E-Foil

Post by staska » Aug 11, 2017 11:12 am

SmokeThroughWires wrote:Howdy folks,

I'm "notafraidtotry's" partner in crime (also on this forum) for an Electric Hydrofoil Board project.
We appear to have been through the same research pains as many others. The biggest hurdle we are coming up against is the cost of a decent gearbox to reduce RPM down to the right level for a ducted prop (as low KV motors seem to be pretty none existent). Sadly our budget is limited. We're getting very bored of searching for products online!

My latest train of thought, in an attempt to come up with a workable, affordable solution is this:

Motor housed in the board with a drive shaft down through the foil mast. A Right angle (1:1) gearbox at the bottom to direct the drive shaft out backwards for prop (ducted), or perhaps even a "T" gearbox with props front and rear of the foil mast (counter rotating).
As for the motor in the board... (this is the radical bit).... an eBike Hub motor used as a belt drive onto a smaller gear on the top of the drive shaft.........
Sketch -eFoil.jpg
Excuse the dodgy sketch - I had run out of fag-packets.

My thoughts: eBike hubs are cheap and in abundance. They tend to be very low KV, fairly high power (have been looking at 3000w+ options) and robust. Designing the rest of the system would also be very easy, as many of them come with ESC's etc. Provided I can get the cooling right (which I have a few ideas for) I'm struggling to see reasons this wouldn't work.

I'd greatly appreciate if people could please point out the flaws in my corner-cutting design!

SmokeThroughWires
I had same ide few pages back. Just lok into 2-3 hp outbard leg and you will got almost all that you need as size guide. Not smaller.. As motor i have posted photo of 2.2 kw generator. Its working rpm is close to 3600. And its holds this power all time. Mast is main problem. It should be done from aluminium. Plus integrated gearbox. Order some bevel gears from china.

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Re: Electric Hydrofoil/E-Foil

Post by kiter_UK » Aug 12, 2017 3:39 am

I am a kite foiler and planning on joining in fun as a winter project.

During my research I came across this

http://people.cst.cmich.edu/yelam1k/ase ... 7-1-DR.pdf

Don't know if people have already seen this on their research. Very good in my view.

Says to me that these projects need a bigger foil than normal kitesurf size ones to achieve decent top speeds. (C.f. e foil top speed)

You are, say, doubling or tripling the drag by adding the motor/gearbox/prop. The vast majority of the motor max power is required get initial lift off. The better the design of the motor/prop set up for lift off, the worse the top speed. The impact of prop on drag is much greater than foil size. Therefore a bigger foil means a less power required to achieve lift off, so for a given motor the gearbox/prop combo can be designed for higher top speed).

https://www.takuma-concept.com/#home

Too big a foil and I reckon it will become v slow to steer. Also I think it will require even more of a forward stance than the motor already creates during acceleration phase. I notice that some sup foils have quite a large rear foil. Could be this is an option to keep centre of lift further back. (Don't really get yet how front and back foils affect performance...)

I reckon worth looking at the difference between kite and sup foils. Maybe sup size better or somewhere in between.

Don't know if this logic is right or flawed, but thought I'd share. I know a few people are looking at designing bespoke foils.

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Re: Electric Hydrofoil/E-Foil

Post by kiter_UK » Aug 12, 2017 3:47 am

Thought I'd post some foil details - Naish thrust

NB. DOWNTURNED TIPS FOR EARLY LIFT OFF?

http://www.standuppaddleboarding.co.uk/ ... earch=foil

Designed in collaboration with Kai Lenny, the Thrust Surf Hydrofoil develops lift at low speed, and launches with minimal effort. The combination of early take-off and excellent maneuverability makes it great for waveriding, cruising or racing. The extra long fuselage creates a large sweet spot and provides stability, while the downturned stabilizer (rear foil) makes waveriding and turning intuitive and easy. The small (55 cm) extruded alloy mast can be retrofitted to any style box system. Whether surfing or downwinding, the Thrust Surf Foil will keep you stoked session after session!

WING
High lift foil with downturned wingtips designed for early take off and maximum maneuverability

WING SIZES
Medium Wing - High lift, downturned wingtips – for riders 120 – 170 lbs*
Large Wing - High lift, downturned wingtips – for riders 160 – 210 lbs*
Aspect Ratio 3.54
Wingspan - M – 60.46 cm/L – 66.24 cm
Surface Area - M – 1032 cm2/ L – 1236 cm2
Mast Size - 55 cm
Fuselage Length - 64.2 cm

STANDARD MAST SIZE
55 cm
All Naish Foil Systems include a premium padded cover.


CONSTRUCTION
Aircraft Grade Aluminum 6061 mast and fuselage
Fiberglass Composite wings
316 Stainless Steel Hardware

staska
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Re: Electric Hydrofoil/E-Foil

Post by staska » Aug 12, 2017 5:48 am

kiter_UK wrote:I am a kite foiler and planning on joining in fun as a winter project.

During my research I came across this

http://people.cst.cmich.edu/yelam1k/ase ... 7-1-DR.pdf

Don't know if people have already seen this on their research. Very good in my view.

Says to me that these projects need a bigger foil than normal kitesurf size ones to achieve decent top speeds. (C.f. e foil top speed)

You are, say, doubling or tripling the drag by adding the motor/gearbox/prop. The vast majority of the motor max power is required get initial lift off. The better the design of the motor/prop set up for lift off, the worse the top speed. The impact of prop on drag is much greater than foil size. Therefore a bigger foil means a less power required to achieve lift off, so for a given motor the gearbox/prop combo can be designed for higher top speed).

https://www.takuma-concept.com/#home

Too big a foil and I reckon it will become v slow to steer. Also I think it will require even more of a forward stance than the motor already creates during acceleration phase. I notice that some sup foils have quite a large rear foil. Could be this is an option to keep centre of lift further back. (Don't really get yet how front and back foils affect performance...)

I reckon worth looking at the difference between kite and sup foils. Maybe sup size better or somewhere in between.

Don't know if this logic is right or flawed, but thought I'd share. I know a few people are looking at designing bespoke foils.
First link is super. From my research v shaped foil is not the only option. And its limits wave sizes. Easies is bipLane configuration. Lift on two wings, cruise at one. I think we need someone to test how big motor or gearbox we could use for minimum penalties in performance. Or go to fishtail instead of prop.

Hiorth
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Re: Electric Hydrofoil/E-Foil

Post by Hiorth » Aug 12, 2017 6:20 pm

Going foiling (hopefully) tomorrow. We have never foiled before, so it will be interesting, but we have some experience with water sports, so I guess it will work out.

Will start with the next version (V2), a 18650 battery pack and counter-rotating propellers (for fun) next week. Would be glad if somebody have inputs on a cheap (and good) battery-cell supplier.



More photos/video:
https://www.facebook.com/nikolai.hiorth ... nref=story
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Last edited by Hiorth on Aug 12, 2017 7:18 pm, edited 1 time in total.

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parabellum
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Re: Electric Hydrofoil/E-Foil

Post by parabellum » Aug 12, 2017 6:56 pm

Hiorth wrote: a 16580 battery pack
Is it 18650?
P.S. Nice machine. Do not forget, we all love videos.

Hiorth
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Posts: 57
Joined: Jul 15, 2017 5:20 pm

Re: Electric Hydrofoil/E-Foil

Post by Hiorth » Aug 12, 2017 7:18 pm

parabellum wrote:
Hiorth wrote: a 16580 battery pack
Is it 18650?
P.S. Nice machine. Do not forget, we all love videos.
My bad, mixed the numbers, I ment 18650. Will post some video of the machine tomorrow.

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