Electric Surf Board

so, i ordered these motors and esc https://www.alibaba.com/product-detail/8kw-watercooling-BLDC-motors-for-electric_60652252411.html?spm=a2700.7724838.2017115.108.67c9179apjm9wP

i know its from china, but if the kv and kw rating are as they advertise, then it should work pretty well.

the board i intend to shape from eps foam, then cover with carbon fiber.

the impeller itself will be 76mm diameter, with a 70mm pitch, made from carbon fiber. (luckily i have a small carbon fiber shop at my disposal) im going to machine a top and bottom aluminium mould. i would usually use pre preg carbon in the autoclave, but this time i will use dry carbon cloth, and inject epoxy resin into the mould.

the rest of the water jet will be made from a selection of laser cuts, some custom machined parts, and some off the shelf bearings and water seals. (luckily i also have a fabrication shop at my disposal)

personally, i think the thrust problem mathias was having was not down to the motor, but i think he needed a more diverging nozzle. i guess ill find out over the next weeks.

anyway, if anyone wants the designs/models etc to use for their own project, or to improve them some way, then i can upload them or email them or something
 
Thats actually a really awsome thing you are going to do!
Do you have already any experience in mould making for carbon fibre?
Why is the stator directly in the nozzle?

Cheers
 
thanks. well im hoping it will work out pretty well!

the motor will sit further up the tube into the board, but if by "stator" you mean the fin like things in the nozzle, they are to stop the water/jet from just spinning/vortexing the water jet. it should increase thrust, and efficiency. they will be welded to a laser cut "bearing cradle" just behind the prop, this should cut down any vibration of the prop, and mean that i can get my prop super close to the tube walls.

well, on the carbon side, i own a small carbon factory that i setup about 5 years ago producing low volumes of high precision carbon parts, so it shouldnt cause too many unsolvable problems
 

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The 7kw of your motor is the peak power I guess. Same for the ESC.
Did you already order ? Would be very interesting to see a test of this motor under load. (alienpowersystems offers same motor)
 
yeah ive already ordered about 2 weeks ago, should be arriving any day.

the motor is listed as 8kw, but i guess ill see how it is in the "real world" after some testing.

i looked at the alien power systems motors, but this motor is apparently 250 kv, and 300amp, so its in the right rev range, and should have some decent torque, plus it was pretty cheap. im guessing all the alien power systems motors are probably made in china anyway.

personally, i think (and maybe im completely wrong) that 8 kw motor should be more than sufficient. i mean its basically 10.7hp gas equivalent. i think that its a case of the prop and jets being properly tuned toward optimum thrust. partly thats why i plan to injection mould carbon fiber props, so i can change the design easily, and the jet nozzle will be detachable, made from a laser cut flange, and piece of pressed stainless tube, so i can change the nozzle angle and find a good balance
 
I am also building a jet surfboard. Carbon Jet-tunnel, selfmade carbon impeller and aluminum nozzle.

As I spend so much time in building the board and parts, I currently tend to buy a Lehner Torqstar + MGM controller.
 
yeah i was looking at the lehner motor, for sure thats gonna have some power!!

i decided though to start off playing with some cheaper motors and see what power i can get out of that, then maybe upgrade if i had to.

post some pics of your progress, i would love to see what you've been working on, plus maybe get some new ideas/inspiration i didnt think about :D
 
chris_kline said:
thanks. well im hoping it will work out pretty well!

the motor will sit further up the tube into the board, but if by "stator" you mean the fin like things in the nozzle, they are to stop the water/jet from just spinning/vortexing the water jet. it should increase thrust, and efficiency. they will be welded to a laser cut "bearing cradle" just behind the prop, this should cut down any vibration of the prop, and mean that i can get my prop super close to the tube walls.

well, on the carbon side, i own a small carbon factory that i setup about 5 years ago producing low volumes of high precision carbon parts, so it shouldnt cause too many unsolvable problems
Click to expand...

Yeah, i know the function of a stator :)
I was just asking because every jet drive I´ve seen has the stator and the nozzle as 2 different parts.... So I was wondering if it may be more efficent to build it like you.

How do you know that 70 mm pitch should do the work?
Would be nice to see some pics of you too!

Currently I´ve also started with this project. I already have a Lehner 3060 with 9/19 windings. On the official website they say that this motor reaches 17 kw at 50.000 rpm. I´m planning to build a watercooled gearbox with a 1:3 ratio. That schould do the trick for the torque...
For the impeller I´m planning a cnc mashined aluminium one. I was thinking to reconstruct a solas 3 blade jetski impeller but with a 80 mm diameter... don´t know guys... what´s your opinion about that?

Cheers
 
the 3060 is an inrunner thats why it has not enough torque and too high rpm for this purpose. Especially for your huge 80mm impeller i guess the 3060 is too small
 
Yes I know, but it should work out with a gearbox. I mean 17 kw... I reduce the rpms and get more torque out of it... or I hope so...
Do you have pics of the stator and the impeller too? What diameter does your jet drive and your nozzle have?

Cheers
 
have not build impeller and stator yet, but will do this in the next days.
 
sorry, my bad, i dont really know the terminology, i didnt realise the "stator" in a jet was called a "stator", but it seems kinda obvious now.

why 70mm pitch? it just looked right for a first try.
 
i have 60mm impeller diameter. i decided to build 60mm when i was also thinking to use 7kw motor. maybe i am too small for the lehner now, but will give it a try first.
 
fabianpusch said:
Hi at all

I have nearly the same setup.
As battery I have used a 16S4P 38140SE Headway configuration and at the moment I am using a 16S1P LiPo from Kokam with crazy 53Ah. The Headway setup was really stable lets say idiot safe but a little heavy.
Cruising time about 25-30 minutes. It is a 48 Ah configuration. Now with the Kokam it should be around 35-40 minutes.
As motor I use also a Lehner and I use the MGM Compro the so called industrial version.
I can post the specs of the controller.

By the way, I am using an Emus BMS with the small cell modules.

The board is fully made of carbon.
If someone is interested, the Headway cells will ne sold for a cheap prize.

Have a nice evening
Click to expand...

Hey fabianpusch, did you buy the Kokam 16S1P LiPo off the shelf? Curious as to weight and price.
 
Hey guys, Im selling some of my stuff... MHZ 80mm Jetdrive and 8x7S 5000mah 60C Lipos all new!! please send me a message if youre interested! (all placed in Darmstadt/Germany)

[strike]MHZ Jetdrive 720€
Lipo 35€ each[/strike]

SOLD!
 
Jetfreak said:
Hey guys, Im selling some of my stuff... MHZ 80mm Jetdrive and 8x7S 5000mah 60C Lipos all new!! please send me a message if youre interested! (all placed in Darmstadt/Germany)

MHZ Jetdrive 720€
Lipo 35€ each
Click to expand...

Why are you selling ? Have a better one ? You give up ?
 
No, got the complete setup as kit and bought a lot of stuff in the past.. so I just switch the stuff :D If somebodys interestet, dont hesitate to contact me!
 
http://www.lehner-shop.com/Outrunner/Torqstar/Torqstar-2-7040::49.html?XTCsid=opo7tlps85lvrqd6rjbfj3p3a2

And if anyone is interessted in the lehner torqstar motor that is used in the lampuga surfboard. I have the lehner torqstar 7040 winding 6 with watercooling. Costed about 1000 euro. Make me a good offer, motor is brand new, except it was tested a few minutes.
 
Bazaki said:
http://www.lehner-shop.com/Outrunner/Torqstar/Torqstar-2-7040::49.html?XTCsid=opo7tlps85lvrqd6rjbfj3p3a2

And if anyone is interessted in the lehner torqstar motor that is used in the lampuga surfboard. I have the lehner torqstar 7040 winding 6 with watercooling. Costed about 1000 euro. Make me a good offer, motor is brand new, except it was tested a few minutes.
Click to expand...


would be very interesting why you are selling it. Is there a better one ?
 
No, i want start another project, and i don 't need such a good and powerfull motor anymore.
 
Hello
I have bought the cells standalone.
To do the connection you can use a bavarian system like used in the ultralight powered paragliders.
The hard thing is to put the cells into a polyamide film.
If you can give me a smart tool to load up pictures I will post some pics of the project.
I have also the 3D Data for the foam and the carbon parts and printed parts.
Bye Fabian
 
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