Another build from Kiwi land


#1

Hi all, another eFoil build from New Zealand here. First all a big thanks to the original innovators (@pacificmeister , @Hiorth and @virus ) as well as everyone else on the forum for the inspiration and sharing design files, parts and knowledge on which most of my design is based. This has been a huge benefit and allows everyone to hopefully improve and innovate further. I was following @pacificmeisters original build videos and have finally got enough parts to start putting something together. Mine is a slow build due to lack of time to put into the project but am hopeful I will be riding before NZ summer ends.
The gearbox finally arrived today (have been waiting months) and am still waiting on the foil, but have most of the other hardware, and am currently 3D printing the rest of the components on my Qidi printer is ABS. I have tested most of the electronics, just need to package into final enclosures etc.

Components:

  • Batteries: Currently have 2x 6S 8000mah batteries that I use for UAVs that I will be using in series for 12s for testing. Plan is to either make or buy if I can find a good source a 12S 22000mah battery (probably 2x 6S for ease of charging etc.)
  • ESC: Seaking HV130A, will be mounted in a separate aluminium enclosure
  • Voltage/Current Sensor: Mauch HS-200-HV
  • Motor: SSS 56114 360kV 6 Pole Inrunner (10mm output shaft)
  • Gearbox: Chinese GHP42-3.78, ratio 3.78:1. Input: Transfer gear attaches straight to motor output shaft. Output: 10mm shaft
  • Prop: ParaProp3 or boat prop style 3D printed (ABS? or PLA?)

Control Board: I am using a teensy microcontroller to drive the ESC. This allows me to add some extra smarts plus the following features:

  • Bluetooth (HC05) control from DIY controller, with signal loss timeout
  • Acceleration/deceleration limiting, to reduce strain on gearbox
  • Fixed throttle control - Can set a fixed max throttle from the controller, then hold throttle full on. This should give a constant throttle to the ESC when learning to get up on foil without having to worry about holding a consistent throttle trigger. Not having any riding experience I’m not sure if this would be beneficial?
  • Monitor battery supply voltage and current via Mauch Sensor. This will then be displayed on an LED for viewing while riding. Will provide voltage and mah warning and then cutoff.
  • Logging voltage, current, throttle, rpm and temperatures (ESC and batteries) to SD card.
  • GPS/accelerometer logging. This data can be used to track speed, distance etc. as well as used for tilt sensors. This is really just a fun to have which I will do once I get riding. Have done this on other projects so should be easy to port across. Also could do actual speed control (i.e launch control) for easy learning for friends who want to try.

Controller: Thanks to @Hiorth for the inspiration with the controller and sharing the STL files. This also has a teensy and Bluetooth device

  • SS495a hall effect sensor for throttle
  • Deadman switch
  • Up and Down buttons
  • Indicator LEDs. Potentially will add a small LED display to get more info from the board (i.e main battery level etc.) in the future.

Board: Custom hack of a cheap old windsurf board, similar to what Hiorth did, i.e cut front and rear to new shape and re-glass. Width and volume of this is small only giving ~70L of volume. This will make it hard to learn with, i.e won’t be able to balance while not moving. Plus it is not thick enough to hide the electronics in the board. After testing I will likely make a custom new board. I have so far cut the back of the board off and started shaping. Will likely leave the front as it for now. I will need to make a flat surface for the mast attachment.

Foil: Chinese ‘Takuma’ style foil. Carbon fibre wings and fuselage with aluminium mast. Front wing size (L63cmW27cm), rear wing (L38.5cmW11cm), mast 80cm.

Back to hacking the board, 3D printing, assembling and testing. Will provide an update and more photos once everything is assembled.


#2

The transfer gear for the gearbox doesn’t have any grub screws on it. Should I be drilling one into it or are these things designed to press fit onto the 10mm shaft and not come off?


#3

I have the same gearbox, and also in nz :blush:. Careful with the centerpiece cog it has a small bullet thing on the back of it that will melt if you don’t have a thrust bearing taking the load. The gear just presses on to the motor shaft apparently


#4

Thanks for the tip. I am planning to use a thrust bearing. Just probably need to make sure it gets preloaded when assembling. Were you able to replace that piece? Hows your build going?


#5

Haven’t looked into replacing it yet, luckily i have a Neugart gearbox here so im just gonna use that for now. Im rebuilding everything into the board atm, hopefully it floats lol. the other problem i had was the whole back end including the motor rotated in the aluminum tube so i had to screw it in at the back by the rubber o rings, im running mine on 16s tho


#6

So my foil finally turned up. It’s definitely alot heavier than expected, see weights below. The front wing is 2kg alone, I would have thought this should be lighter, I guess they must use a heavy core! Does anyone have the weights of there foils?

When I opened the package there are a few dings on the front wing unfortunately so I will have to fill them with epoxy.

Weight calcs kg Material
Front wing 1.935 CF
rear wing 0.346 CF
fuselage 1.274 Alu/steel
Mast mount 0.507 Alu/steel
700mm mast 1.257 Alu



Chinese hydrofoil for efoil?
#7

Hey Glen,

How is the build going,

I remember discussing batteries with you and said I would keep you up to date with my battery finds.

Check out “headway 38120hp” cells… you will be surprised by the discharge rating ha

David.


#8

@DavidC those batteries look great. Cost would work out cheaper than other solutions. There doesn’t appear to be too many diy projects using them. Have you ordered some?

My build has been slow with work and other commitments unfortunately. Still finalising the propulsion unit, some prints take a long time and need to be here to monitor. Also need to finish sanding and glassing the board.

How is yours going?


#9

just got the takuma foil v100 (real) , the front wing is 2.250 kg :wink: