How much does wing size affect top speed?


#1

Hi everyone,

Ive been riding my e-foil a bit using this wing: https://www.aliexpress.com/item/T1-hydrofoil-carbon-wings-foil-alumimum-mast-for-Surfboard-kiteboard-SUP-2018-hot/32836695804.html?spm=2114.search0104.3.31.5b62298bW9w7On&ws_ab_test=searchweb0_0,searchweb201602_2_10152_10151_10065_10344_10130_10068_10547_10342_10343_10340_10548_10341_10696_10084_10083_10618_10307_10131_10132_10133_10059_100031_10103_10624_10623_10622_10621_10620,searchweb201603_16,ppcSwitch_5&algo_expid=36e47ce9-a94e-469f-9c46-10aeb46b2bf3-4&algo_pvid=36e47ce9-a94e-469f-9c46-10aeb46b2bf3&priceBeautifyAB=0, I believe its a clone of the Takuma wing.

I’m curious about what affect the front wing size has on how much speed you can get, now that I’m used to riding on the foil I want more speed, I can get around 25kph at the moment which isn’t fast enough :smile:

Do you think this wing can handle speeds of more than 30kmh or does it have to much drag to reach those speeds efficiently?

It seems like when I increase the throttle to higher levels, the motors work harder without gaining much more speed at all… this is what I’m riding: Jake’s Direct Drive build, NSW, Australia - Success!

Cheers!


#2

I am riding the takuma v100 which is a large wing around 1250 i recall , when i change my propeller to a smaller size with higher pitch i got to 32km/h , more amp as well , and this with a 40mm motor
I think your wing is about the same size , you can go above 30 may be not 40.
The interesting thing to look at , i beleive, is that the speed has to increase ( a lot) when you start to fly
You can get faster and more efficient wing but it is not compatible with your " fuselage" ( Bolt on under )
I guess if you want more speed just try a high pitch smaller diameter maybe , or change the kv
I don’t think you max out the motor yet and above 25 it will not be efficient anyway

Édit: for my expérience with a jet drive outrunner, outrunners do not have a good efficiency when You push them to the limit , if you can mesure your rpm drop under load you Will have your answer ( best is 20-30% i think )
Maybe a ±900 wing for 30km/h?


#3

To determine the Vmax or your foil, you need to have it towed by a boat / jetski or lent to a kitefoiler speed measured with a GPS.

It is not only the wing size that affects speed but especially the thickness (therefore the wing volume) of the airfoil section. The current big supfoil wings have been designed to carry a lot of weight at very low speed (the speed of a wave)

  • 1250cm2 are around 2L
  • 1600cm2 are around 3.5L

Both generate a lot of drag passed 40kph
The fastest 1000- 1200cm2 wings with a low thickness can be found in in the windfoil area.

Next October, Gong will launch a (thin) 1m long windfoil front wing (mostly 80cm “blades” today)
A Moth wingspan is 1.20m. Their 2014 world speed record is 67 kph (36kn)


#4

@Alexandre It does indeed seem to require a lot of power to get above 25kmh… do you have any data on how much current is required for you to go 30km/h?

At the moment I’m using roughly 60 amps to foil, which must be because the motors are being pushed to hard and a lot of the power is being wasted as heat, I think i need some bigger motors so they can handle the power more efficiently.

@SoEFoil All very interesting! I guess my foil has a very thick front wing, so it would be displacing a lot of water, it makes sense that it would not be efficient at higher speeds because of the drag.

I’m considering 3d printing a smaller slim front wing for higher speeds. Any advice on wing shape, airfoil etc?


#5

If you want Numbers i would say 100-120a on 8s , recorded by my esc (?) with pod filed of water for 30-32km/h ( GPS) …
The same propeller is given for 40km/h with the same rpm but with a fast wing , 13s , bigger motor and less weight