Hello,
I have 3 foils and probably they are not fit to my 80kg and my goal of pumpfoiling.
Is there any calculator, for a foil profile?
=> take off point

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Charivari said..
Hello,
I have 3 foils and probably they are not fit to my 80kg and my goal of pumpfoiling.
Is there any calculator, for a foil profile?
=> take off point

Just tell us what the foils are.

A 2000 cm2 low aspect foil will be maybe 6mph for someone your size and a 1000 cm2 high aspect foil may be 8mph. Not a huge difference but in reality you will certainty feel it. I think because board are near planing speeds and create a lot of drag and each mph takes a lot of energy.

Charivari, it's a complex one. I don't know of any calculator out there for that purpose. Even if there was one, there's confounding variables as well...
The big things for getting up early as possible are conditions, gear and stance.
If conditions are lumpy and difficult, there's a good chance your weight will be thrown around more, meaning the board will be changing pitch and roll, which can definitely affect take off.
If you have a big wide long board, it's probably going to be 'stickier' and harder to get going, so you might require a little more speed to get it to lift. A big wing will develop lift but might be hard to manhandle so might not provide the useable lift you need.
If your stance is too front orientated, you'll generally need more speed to get flying. If you can time a swell to pump up on, then that can assist. If you weigh 20kg more, then your min speed will need to be higher compared to someone lighter.
These are things that don't describe the foil shape but can affect your min take off speed.
I think the best thing to do is get out there and try the foils you have or ask advice about which ones you have.

This is really hard to calculate.
To start you need the exact design of your foil and some kind of simulation program to find stall speed. Then to translate it to real world it needs to be compared to foils with a known takeoff speed using the same simulation.

that's before you even get to the pre and post stall characteristics. Some foils will have a lower stall speed, but too sudden of a stall/recovery that makes it hard to takeoff in the real world.
then there's board, sail, waves, technique, tail wing, fuse length etc.

for example just changing the airfoil can make a foil ride like it's 200 cm2 larger or smaller. More span can make a foil more efficient at low speed, which could make it easier to keep a smaller foil up at a low speed.
generally more span, area, and airfoil camber will perform better at low speeds. Short mast length, different tail design, and short fuse length can also aid in takeoff and low speed performance.

A towing tank would probably be able to provide the answer, you just need access to one which may mean a trip to AMC in Tassie if you are in Aus. Probably not the cheap and straightforward way to get the answer you are looking for though!

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wind driven said..
A towing tank would probably be able to provide the answer, you just need access to one which may mean a trip to AMC in Tassie if you are in Aus. Probably not the cheap and straightforward way to get the answer you are looking for though!

Yeah :)
A cheaper tank by towing behind a jetski/boat in calm water with different setups and a GPS, it would give you a lot of info on Takeoff and Stall speed.

But you do not really need this numbers, just get out there on a big board/+1500cm2 foil/+15kt wind and practice.

Guestimate a 70kg or less could learn on a 1200cm2 foil, a 90kg would want a 1900cm2.

Athletic abilities, previous watersports experience and sheer stubbornness to learn count a lot.

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mcrt said..

.Guestimate a 70kg or less could learn on a 1200cm2 foil, a 90kg would want a 1900cm2.

and at 110kg what foil is required?

Hello,

Axis 1300

I don't feel the sweet spot of the foiling point, as a beginner.


GONG

Rise XL
span 90 cm
projected) area of ??1844cm? (2137cm? developed)
volume 3.60L
profile of 3.5cm thick

The voluminous shape of our wings favors low speed flight. No stall..., it's just crazy.

When pumping from dock start or beach start, we recommend the wings as follows:

The XL: from 65kg to 85kg.
The XXL: above 85kg.

=> I found a friend and he is quite well pumping his foil and he tried my one. Yes it flies, but only with really great effort. So proably I need the next foil...

GONG XTL ALLVATOR VELOCE PRO

=> Perhaps the drag of my XL is to big, so I tried the slim version XTL....

Veloce XL-T
wingspan of 97cm
surface 1620cm?
volume 1.36L
very thin profile 1.7cm thick

This wing is for riders around 95kg of good level and all other lower riders who want glide with lift.

=> The dock start must be really fast. If the aplitude is a bit high, than brutally this wing stalls suddenly....

=> Probably I need another wing to learn dock start pumping...

My next try might be Indiana...

Nice would be the lift force at 5 km/h and 10 km/h.
The take off calculation (Input 80 kg), what is the take of lift with this foil? (Experimental I can buy all of them and find it out behind a boat wake foiling, but this seams not feasible).
Nice would be the drag force (How hard is it to drive this wing forward?).
Nice would be the glide distance. How far the foil will glide when it starts with 10 km/h?
Nice would be the maximum speed (Input 300 W, NASA curve of a fit healthy men)

Cheers

P.S. An airfoil DB exists...
www.airfoiltools.com/index

Those big Gong Rise wings can fly at like 5mph if you are 65kg. It's almost unbelievable.

We towed a Curve XL this weekend at around 5-6mph. If you want to learn and go slow they are great for that.

Select to expand quote

Charivari said..
Hello,

Axis 1300

I don't feel the sweet spot of the foiling point, as a beginner.


GONG

Rise XL
span 90 cm
projected) area of ??1844cm? (2137cm? developed)
volume 3.60L
profile of 3.5cm thick

The voluminous shape of our wings favors low speed flight. No stall..., it's just crazy.

When pumping from dock start or beach start, we recommend the wings as follows:

The XL: from 65kg to 85kg.
The XXL: above 85kg.

=> I found a friend and he is quite well pumping his foil and he tried my one. Yes it flies, but only with really great effort. So proably I need the next foil...

GONG XTL ALLVATOR VELOCE PRO

=> Perhaps the drag of my XL is to big, so I tried the slim version XTL....

Veloce XL-T
wingspan of 97cm
surface 1620cm?
volume 1.36L
very thin profile 1.7cm thick

This wing is for riders around 95kg of good level and all other lower riders who want glide with lift.

=> The dock start must be really fast. If the aplitude is a bit high, than brutally this wing stalls suddenly....

=> Probably I need another wing to learn dock start pumping...

My next try might be Indiana...

Nice would be the lift force at 5 km/h and 10 km/h.
The take off calculation (Input 80 kg), what is the take of lift with this foil? (Experimental I can buy all of them and find it out behind a boat wake foiling, but this seams not feasible).
Nice would be the drag force (How hard is it to drive this wing forward?).
Nice would be the glide distance. How far the foil will glide when it starts with 10 km/h?
Nice would be the maximum speed (Input 300 W, NASA curve of a fit healthy men)

Cheers

P.S. An airfoil DB exists...
www.airfoiltools.com/index

This guy makes the most technical foil comparisons of all the reviewers i know.

An maybe worth checking the efoil DIY guys at foil.zone , they might have some data.