@SoEFoil and @Frage I have abandoned the round form factor, it’s just plain easier to make it in a rectangular form factor that is more compact, cheaper, and can do more power. Here are some CAD images, it fits in a 55mm circle. The board dimensions are 2" x 3.5" x .9".
It is based on the VESC spec, though I am using some different parts and a little different configuration. Volts is up to 60V or 14s, current capability seems to be around 110A input for a minute or so, which is 150A into the motor. The newest version is what I would like to sell, and that comes Friday or Saturday. I will publish video of the test results.
PowerGlider has been running the old version of the design for a few months, and he typically runs a 12S pack at around 70A from the battery and 110-120A into the motor.
Outrunner motors: 6384PG 100Kv from @PowerGlider being fully tested
If I remember well, a efoil from water to flying position, you draw 1/3 less amp (0.333) eg from 1500W floating (archimedian) to 1000W flying = you multiply by a 2/3 factor that is 0.667
With the above figures (12s= constant) provided from an esurf (that doesn’t fly) ,
A- you mount a hydrofoil which adds 10% drag when not flying (floating)= 70x1.1 = 77A battery and 115x1.1 = 126A into the motor
B- when you take off you loose 33% drag : 77x0.667 = 51A from the battery and 126x0.667=84 A into the motor
The net gain between a running esurf and a flying efoil = 2/3 x 1.1 = 0.73 that is a 27% AMP saving. Let’s check: 70 x 0.73 = 51A and 115 x 0.73 = 84A as in B above.
Commercial solution tests as benchmarks: @Jezza and @rcjetman testing their Flying Rodeo setup will hopefully provide interesting figures from their data loggers
Interesting and useful calculation. Both planning hull and foil has in some respect same properties. To fly you need for a moment more power but then requirement decreases. Planning hull(surf) same thing, to get on plane need more power but to stay there, slightly less again. Before flying & planning, think the plain surfer has less drag, think 10 % is possible if not more. When flying the foil has less drag on same speed than surf without foil, but 27% sounds pretty much, more than expected for fixed wing foil. Do we have practical example with same motor/prop on speed range 20-25 kph( foil surf vs none foil)?
This thing with not planning and planning with a hull is nothing digital. It is more like a slight gradient change if you compare power/velocity. At least i never experienced any drop in power when hitting the throttle. So i need 3.6kW to keep 19-21km/h while foilers report 1.2kW and even less for foiling. Anyhow, you will need as much power as possible to get fast into the foiling mode, and there every amp you get counts. The good thing with Vesc is you can protect your motor from being overloaded and thereby overheated and also the rest of your equipment like cables plugs gearbox etc is not stressed so much including the ESC itself. The flat backside of Nicks Vesc is intended for easy cooling, so you can have water cooling without a pump, hoses and so on by a simple cooling plate which is wetted from the outside of your box. It is very compact and light.
The surf hull is relative narrow so the transition for “getting over the hump”, in to planning mode is probably not that visible on a surfboard as any other planning hull so your observations are accurate.
3.6KW on prop shaft should be 30 +km/h, but we have pretty much power losses on the way from the battery so that explains the difference. 1.2kw for foiling same speed is indeed a huge difference, comparison is hard if hardware, board an possible weight is not identical. Anyway still significant gain.
My wild guess is that on higher speeds the fixed size foil will loose advantage(in calm waters) as the vetted surface will remain the same but on no foil it will decrease.
I will start my project without the foil, lets see what the result will be. Keyboard building is easier than actual building:). Now have some parts, 2 esc but only one motor, one lost in the mail. Aliexpress is OK only if you have very good patience…
Just installed a swordfish ESC but am unable to find the APP windows keeps telling me I need installed to run the program. Swordfish has not responded to me request for help. Any suggestions would be greatly appreciated.