ฝัง
- เผยแพร่เมื่อ 6 ก.ย. 2024
- The first build video is here: • Homemade EFoil Build: ...
You're going to have questions! I will cover most of the details in a future video, however here's the basics:
The goal wasn't a full e-foil, but e-assist, more like the @foildrive product, but integrated like an e-foil.
The board is my attempt at a "Kalama Clone", shamelessly copied from photos of Dave Kalama's amazing E3 downwind board. Modified to have twin stringers, an internal hold for batteries, and a through hull to bring the wires out next to the mast. Plus you could, like, keep a banana in there if you get hungry. Build photos coming soon.
@axisfoils3588 AXIS PNG1150 and 460 stabilizer with standard fuse and 65cm mast.
@FlipskyTech F5085 "waterproof" motor with 70A VESC controller. Rated at 650W. This is barely enough motor.
Folding propeller design shamelessly copied from the foildrive design.
Amazing footage by my very patient wife...
What is the minimum wattage need to lift off and enter a pump?
Great question... my feeling that once on foil you only need about 200 to 250W to keep the PNG1150 flying... this is based on my pump foiling effort compared to a stationary bike with a wattmeter.... Now that doesn't include getting off the water... the motor is using at least 650W here and I have to add probably 100-150W of pumping to help it lift out of the water.
So I'd say for this setup a 750W to 1kW burst is needed to break the tension and get up on foil... weight dependent. I weigh about 165lbs... my wife who weighs less than me can just kind of half-pump to break the tension. I think it's pretty safe to over-power the a motor in water for a short period of time.
If you use a longer board (barracuda style) you may be able to lift off at 450W or so, which is probably what those flatwater paddle-up guys are pushing out with their massive deltoids and young legs.
The crux of all this is the propeller and motor efficiency curves. I need to do a lot of research there. The folding prop is not as efficient as a static prop, and I have no idea at what RPM the motor is most efficient. I feel there's probably 10-15% efficiency wasted here. The prop will have to be designed to be efficient at the motor ideal RPM, and without getting deep into math, this is going to require lots of trial and error.
To add to this comment, I managed to get some telemetry data today... I can pull 900W max during takeoff with a new prop and light pumping... so takeoff is still >1000W.
However, I can fly with as little as 600 to 650W.
The interesting thing is that at 900W, I'm losing 90W to the battery internal resistance and wiring, probably losing 20% more at the motor by not being in the right RPM, and losing at least 25% at the propeller... So if I can re-design the battery, characterize the motor, and design a propeller to work at the ideal motor RPM I could probably claw back some noticeable power.
You're aweseome thanks!