Nicks Jet direct drive Build


#1

Hi my names Nick and I live in Perth Western Australia

Ive been on the forum pretty much since it started

Im a keen kite surfer and have been foiling for a couple of years now

any way back to the point.

Im building a direct drive jet 64mm

over the next few weeks I will upload pics and progress reports

I received my 3D printer back in August last year and have been building slowly ever since.


#2

started by doing a few test prints

I have never done 3d drawing so its been a steep learning curve

I chose sketch up as it seemed to do everything I needed to at the time

But it looks like im going to have to move to something better soon


#3

next came the small accident

wing and hand came into contact

a good reminder how sharp the wings can be.

Thats one of the reasons I chose a jet drive as the prop is enclosed and safer for your little toes


#4

I tried acetone smoothing

But did not get the results I was after

Much better to sand coat with epoxy and sand and epoxy and sand

a lot of work but perfect finish


#5

Ouch, hope it heals up ok Nick!
Cool jet impeller and setup, its come a long way from your first version. amazing how much refining there is eh!


#6

yep its amazing how much has changed on this journey

its a labour of love thats for sure

the Cut was back in August last year just after I started this project.

and I did it kite surfing on my foil


#7

next came the batteries
where to start

so I started with 2 x 3s giving me 6S 8000Mah

then the test rig to test the design

I don’t have any pics of the first design as I moved on very quickly

but for design 2 I dis a mock up on my Moses Vorace

IMG_5131
IMG_5156

lots more to come


#8

the motor

well I had no idea really and the forum had not started

so I started with a

1340kv Leopard 5692

as you can imagine I quickly moved on

one thing it showed that the principal was proved

with the right motor and ESC etc this thing could really work


#9


#10

a few of the props Ive printed and tested


#11

so I then moved on to 2 x 6S batteries
a 790 KV motor
and a load more parts


#12

ESC is a HiFei Swordfish Pro+ 300A

full water proof and has built in data logging

complete with capacitors for 15S batteries if I ever go that high


#13

-Nick: “Hi, my name is Nick and i am an efoil addict.”

-The crowd: “Hiiiii Niiick!”

But srsly :smile:
U tested the impellers? U got any idea what could work like which shape is better, how many blades etc etc? Props and imps are the biggest mystery here :smiley:

P.s. That build is getting it on!


#14

Awesome Nick! Thanks for sharing all your experiences with us. Good luck and keep it coming.


#15

Hey Nick, I think you will be better off with a smaller impeller still. I started out with 110mm prop with various pitches, and working my way down 80mm, 64mm, 60mm, 58mm, 56mm. With the proper pitch (super low pitch) I could get the same thrust with 110mm prop direct drive as I could with a small diameter setup. We know from this forum that a 56mm impeller works well for a small 56 diameter motor so best not stray too far from that in my opinion. These little motors don’t have enough torque for crank around a larger impeller and prop for high thrust so smaller is better. smaller get higher RPMs and have much more thrust but in smaller jet of water VS larger prop pushing more water slower which requires more torque/reduction gear.

A 58mm impeller requires roughly 6,000 watts power, and a 64mm impeller requires 12,000 watts. Huge difference with an impeller only being a few millimeters larger. Stats from MHZ website.

Yes the 56 series inrunners say they give out 12,000- 15,000 watts but when you run the numbers which are 120A x 50v = 6000w, then calculate efficiency which 70-80% for rough numbers sake you are looking at only providing $4,200w to 4,800w mechanical power, meaning you’re way under powered for a 64mm impeller.

Hope this helps shed some lite!


#16

Thanks for sharing your progress. How did you hurt your hand???


#17

Hi Max

the cut was from kite surfing
on a fall my hand hit one of the trailing edges to a wing


#18

Next came the mast and wings

although I have a few normal kite surf foil wings I can try

so I ordered a set from Manta

large front wing abut not as large as some I have seen on here


#19

as you can see the wires and water tube for cooling the ESC are fed up inside the mast

water is taken from the discharge section of the jet and fed to the ESC no pump required


#20

Out let nozzle with bearing fitted