The square shaft is a good idea, especially for gear reduction high torque prop. The printed props may be not as strong.
This page has more ideas about alternative ways to connect shaft and hubs. https://www.stoffelpolygonsystems.com/
Probably this one scaled down 
2 Likes
Is anyone building jet drive (impeller) if so what have you come up with thus far?
I have found that impellers 50-80mm like 16,000 RPM and 16,000 is also the sweet spot for many motors for electrical efficiency. Im looking for some impeller designs and nozzle with diffuser to 3D print and test.
Hi!
I used solas prop in the begining… I had 300kv motor with 4:1gearbox 12s lipo and around 3300rmp unloaded. Speed was around 12-13mph-foiling.For me at 75kg was enough but my 100kg friend couldn’t get on the foil… I got around 35A…
best regards
Simon
Hello
Very interesting. You got only 36 amps???in cruise mode? It’s mean 4x12x36= only 1800w! That’s true?
My setying is 8s, direct drive and 130kv! What do you thing about?
Why do you change it?
I build 80mm jet with fully molded carbon fibre impeller at the beginning 
,but efficiency was too bad, I think it is very important (for classic jet) that the nozzle of the jet pushes water close to the air so the air can be soaked in to the steam(kinda mixture air-water). it seams weird but when water travel thru the air gets more kinetic energy- it can accelerate.Under the water there is no air after water leaving the nozzle so the acceleration is smaller…
I make classics jet-surf from it
https://instagram.com/p/BUrB5G0jHfv/
For foil I think proper propeller would be the best…
best regards
Simon
…when foiling. I changed it becouse with the duct was like 20%less power, even couldn’t get on the foil 
. Then @Hiorth send me his design and it worked pretty well!! thank you Nikolai!
Then I designed my own 3bladed kort, with blade area close to the Nikolais prop. So now I can play with different pitch and blade shape…
It would be really nice if you could run it direct-drive,but can be to much load for the motor…
simon
10 Likes
How did you make this? What Motor?
This might be the way to go… but sofar to expensive… We`ll see what future brings;-)
Hi Mate,
Sorry for the delay. Was busy with work and dealing with my boss.
I’m getting an error saying only pictures can be uploaded. As such you will find all the files needed from the motor back in the dropbox link provided. PLEASE NOTE all the files are designed to be printed on a Prusa i3MK2S in Polymaker PC-Max. I’m not sure what will happen if you print them in any other material or printer! Please pay attention to tolerances of your own printer**
https://www.dropbox.com/sh/hchzurgjxvfq3ak/AADJzjO3UayjdJFEhROsSw1ba?dl=0
Cheers,
Aaron
6 Likes
Thanks for these, I like the look of your prop… The prop wasn’t there though, all the other files but not the prop.
Sorry David. Epic fail on my part. Give me 5hr to upload it. I’m just out on the boat at the moment.
Aaron
No worries… Appreciate it
Prop now uploaded. Enjoy. Let me know if you need anything else and how you get on with it (if you use it).
A
… just opened a new category → :
1 Like
Did you find any research on your theory of water pushing a water/air mix has more thrust? I cant seem to find anything on this, hoping you you did?
Does anyone sand their 3D printed propellers? Having a smooth surface would be critical to efficiency, specially since they are spinning so fast. I sanded a test piece of PLA to 600 grit and it polishes up really nice! I’d love to hear about someone’s before and after test results (I’m not to that point yet).