Fórum Foil

At the moment there is a lot of manual work, but I like the challenge. I have to go away for a couple of weeks so will not be near a printer. This sounds like a task to keep me occupied to see if I can make it parametric. AI is amazing but don’t forget to checks its work. Pitch a couple of them against each other to make sure they agree. I did manage to fit the gears into the 52mm hub

Any chance you could make your design parametric…? For example I’ve been playing with AI to come up with parameters for my use case and setup specifications : Diameter: 145mm to 150mm Pitch: 106mm to 113mm Expanded Area Ratio (EAR): 0.45 to 0.55 Rake: 10° to 15° positive rake

Maytech Pro Kit 72V Jet Propulsion System MTWJ20KW + 300A ESC for Yacht Jetski Jet Boat Jetboard Jet Kayak

what motor are you looking at?

I am just following the maths and looking at the logs from my own board. Open to hearing what is normal/out there. Different manufacturers / KV will be very different. For instance the motor the 140mm design is for is around 450KV and a 4:1 gearbox. If you look at the flipsky power sheets for a motor like the 6374 @ 36V the no load speed is about 5400RPM and 93.4% efficiency 5045RPM and max power at 2673RPM. with a 12S battery your voltage and these numbers should be higher if the ESC/Battery can provide the current.

Jb69: My target is roughly 20–30 km/h with the prop in the 4–5k RPM range. Wow, thats plenty rpm. My best setup ist going 2.300rpm with 20km/h. Non Fold. Maybe foldables are/need less Pitch, but 5k Sounds crazy for me with so Low speed

Nice work on the gear mech. Lots of talk on the foil drive forums with having to prespool motors to get all three blades to open nicely especially on integrated masts with more laminar flows. This should help solve this.

A few people have asked for the STL/STEP files. I’m happy to share them once the design settles down a bit. There are still a few things changing around the geared folding mechanism, hub stiffness and the 140 mm version. I’ll probably release them under CC BY-NC-SA 4.0 , likely using GitHub for the CAD/source files and MakerWorld for the print-ready files and tested print profiles . There isn’t really one universal “correct” prop though. The way I’m sizing these is: motor KV + voltage ↓ motor RPM ↓ gear ratio ↓ prop RPM ↓ target speed ↓ pitch, allowing for slip ↓ diameter / blade area / current From the motor spec: motor RPM ≈ KV × voltage If you have VESC logs you can cross-check it with: motor RPM = ERPM / pole pairs and then: prop RPM = motor RPM / gearbox ratio As a quick example, 65,000 ERPM with 3 pole pairs and a 4:1 gearbox works out at roughly: 65,000 / 3 / 4 ≈ 5,400 prop RPM For pitch I’m currently using about 30% slip as a starting point: actual speed ≈ theoretical pitch speed × 0.70 or working backwards: required pitch ≈ target speed / (prop RPM × 0.70) My target is roughly 20–30 km/h with the prop in the 4–5k RPM range. On my board I also only have about 80 mm from shaft centreline to the fuselage , which is what drove the Takuma-specific version to 140 mm diameter and about 10 mm nominal tip clearance. For the blade shape I’m starting with a Wageningen Series B propeller design, using relatively low blade area and minimal rake. I then take that generated prop in

From what I have seen over the past several months, and it has been discussed on the forum, the AI spam removal setting is on high/very conservative. The Admins seem to be making corrections when notified. There are a lot of scammers in the buy sell section, which has bled over to the rest of the site.

Happened the same to me. In a thread about efoil bateries exploding I shared something that happened to a friend with a picture of the aftermath. After that I have been banned for almost one year now with no explanation.

Loving all the development on these and looking forward to printing a set to try once you are happy with them. I’m keen to try smaller length motors to save a little weight so the option of smaller diameter props is great.

Jan12: I think the group that buys Foil Drive simply has the money to spend and do not really care that much if it’s 3k or 5k. And the group that does not want to afford FD is in almost the same situation and won’t buy no matter if it’s 3k or 5k. This is a very accurate statement. When you look at the cost of most foils, they are insane! So guys don’t mind spending in the upper region. Jan12: I am surprised there is not more after market options yet, like replacement batteries or motors for significantly less than FD is asking. FD continuously drive 3rd party options as breach of warranty behind closed doors. Technically this breaches consumer protection laws all over the world, but because its behind their Facebook group and their core influencers support them, they can control it and get away with it. They’ve left a big door open to a better product though. Now its to see if anyone can come up with a solid plan to trump them…