Contact   Imprint   Advertising   Guidelines

80 knots on a foilkite

For all foil kite riders
Schietwedder
Rare Poster
Posts: 11
Joined: Sun Dec 09, 2018 1:35 pm
Kiting since: 2008
Local Beach: Surendorf, Kiel, Germany
Gear: Diy Gear
Brand Affiliation: None
Has thanked: 0
Been thanked: 2 times

80 knots on a foilkite

Postby Schietwedder » Tue Nov 19, 2019 5:22 pm

I just came across the Swiss group of university students, engineers and scientists from Switzerland, who want to design and build a kiteboat using a Foilkite going 80Knots breaking the world speed record. https://sp80.ch/

Now besides the problem with traction, platform aerodynamics and cavitation, projects like this usually have to face, lets assume they work out a platform which can go 80 knots....

What will a foil kite do in 80 knots boatspeed (maybe 100knots apparent) ? Maybe some Paragliders, Race Foil kiters and kite designers among us could help out on this discussion.
I wonder what a foilkite would behave like in those high and low pressures acting on the wings surfaces and also from the inside.
One should get quite some canopy deformation, at least on the wings upper surface where positive pressure from the inside and negative pressure on the outside will not cancel out but add up.

Will light nylon ripstop still work? Maybe we get a North sails 3DL kite from composite laminate in the end or even a composite wing with very few flying lines.
What will be about drag from the flying lines and bridles (pipes/round cylinder has a horrible resistance coefficent and there will be quite some loads on the bridle so they will be quite thick)
Where in kitefoiling is the lift to drag ratio a problem? On the foil or on the kite? Which prevents you from going faster? Of course besides having to go on a up and down course through maneuvers which brings some compromises.

I have no Idea with those kinds of speeds maybe if you size a foilkite up the loads/pressures is actually not a problem, hard to say without experience.

Are there people who went 100km/h and more on a Buggy/Snowkite on Ice?

Some brainfood:



Attachments
Unbenannt.png
Picture from their FB account
Unbenannt.png (85.35 KiB) Viewed 847 times

tkaraszewski
Frequent Poster
Posts: 236
Joined: Tue Aug 07, 2018 7:03 pm
Kiting since: 2016
Local Beach: Hood River
Style: Hydrofoil
Gear: Moses/F-One/Flysurfer mostly
Brand Affiliation: None
Has thanked: 10 times
Been thanked: 54 times

Re: 80 knots on a foilkite

Postby tkaraszewski » Tue Nov 19, 2019 6:49 pm

It seems easy enough to test this with a kite flying off the back of a car. Rig up your test kite at a place like Bonneville on a calm day and drive the car up to your target speed and see if your kite comes apart. Making a kite that flies in high winds stronger isn't really a problem, though, it'll just be heavy, but that doesn't matter at these windspeeds. Use carbon reinforcements like in boat sails.

But it would be an easy enough experiment to do by tethering an existing foil kite in the back of of a pickup truck and accelerating up to speed.

> One should get quite some canopy deformation, at least on the wings upper surface where positive pressure from the inside and negative pressure on the outside will not cancel out but add up.

Why do you say this? Positive pressure from underneath combined with negative pressure from above never cancel, there's nothing that changes somewhere between the current top end of kites (50-ish knots?) and 80 knots that would affect this.

plummet
Very Frequent Poster
Posts: 6451
Joined: Sat Aug 29, 2009 11:25 pm
Kiting since: 33
Local Beach: EE
Favorite Beaches: NZ
Style: Terrain riding
Gear: Old wornout ozone.
Plummet hydrofoil and mutant
Brand Affiliation: None
Has thanked: 4 times
Been thanked: 82 times

Re: 80 knots on a foilkite

Postby plummet » Tue Nov 19, 2019 7:55 pm

World speed record for kiting is 82.9 mph as far as I know.

Held by a kite buggy on a dry lake bed with a fixed bridle foil race kite.

I think the biggest problem is the parasitic drag from bridles and lines.

As ground speed increases the wi d window shifts further and further back. The kite has to fly far forward into the window. There comes a point where the kite/craft cannot go any faster due to the limitation of drag and apparent wind window angles.

Ultimately it won't be kites holding sailing speed records due to lines/bridle drag.


These users thanked the author plummet for the post:
edt (Wed Nov 20, 2019 6:10 am)
Rating: 10%

Mossy 757
Very Frequent Poster
Posts: 1725
Joined: Fri Sep 11, 2015 5:10 pm
Kiting since: 2013
Local Beach: First Landing State Park, Virginia Beach Oceanfront
Style: Kitefoil
Gear: Delta Hydrofoil and board. Cabrinha Velocity 9m, Flysurfer Sonic2 11m, Ozone R1V2 15m
Has thanked: 30 times
Been thanked: 41 times

Re: 80 knots on a foilkite

Postby Mossy 757 » Wed Nov 20, 2019 12:13 am

plummet wrote:
Tue Nov 19, 2019 7:55 pm
Ultimately it won't be kites holding sailing speed records due to lines/bridle drag.
Yeah, I'd put my money on foiling craft with hwingsails on something like the Vestas sail rocket or maybe one of these new America's Cup monofoilers if they went back to a wing instead of a soft sail.

User avatar
kgb
Frequent Poster
Posts: 207
Joined: Wed Jun 25, 2003 10:21 pm
Kiting since: 9
Local Beach: Montrose Beach
Favorite Beaches: Cape Hatteras, NC & Tarifa, Spain
Style: Freeriding and wave riding.
Gear: Kite - Slingshot Fuel
Board - North Jaime Pro (twintip)
Brand Affiliation: None at all.
Location: Chicago, IL
Has thanked: 3 times
Been thanked: 16 times
Contact:

Re: 80 knots on a foilkite

Postby kgb » Wed Nov 20, 2019 1:09 am

This IS something like sail rocket

And an ac75 has no chance of 65 let alone 80 kts solid rig or not.

RedSky
Medium Poster
Posts: 190
Joined: Wed Jul 23, 2014 12:47 am
Kiting since: 1997
Local Beach: Camber, +Croydon
Gear: Genetrix Hydra
Has thanked: 3 times
Been thanked: 4 times

Re: 80 knots on a foilkite

Postby RedSky » Wed Nov 20, 2019 4:48 am



88mph / 76knts / 142.9 kph Cabrinha Switchblade

If you want to go fast then use a small kite in very high wind. I don't know much about sailing on water but I imagine that using a hydrofoil design and two small kites in very high wind might work.
One small kite won't be enough and a larger kite has too much drag.

bohme
Rare Poster
Posts: 18
Joined: Fri Apr 22, 2016 12:01 pm
Kiting since: 2002
Local Beach: Ringkøbing
Favorite Beaches: Hvide Sande
Style: Foiling
Gear: Worn
Brand Affiliation: DIY
Has thanked: 3 times
Been thanked: 1 time

Re: 80 knots on a foilkite

Postby bohme » Wed Nov 20, 2019 1:13 pm

Wow. 76kn on a switchblade.
Apparently, the stern-steerer ice yacht Debutaunte was timed over a measured mile at 124 knots on the ice of Lake Winnebago in 1938.
I guess you do not need high efficiency. You might even consider the complete opposite.
If you want to do 80kn, dig a trench and go out i 160kn wind with an old fashioned parachute?
Perhaps kiteloop your Switchblade :-D

joriws
Very Frequent Poster
Posts: 819
Joined: Wed Nov 24, 2010 11:03 am
Kiting since: 0
Gear: Flysurfer, HQ, LF, Nobile, North, Ozone
Brand Affiliation: None
Has thanked: 10 times
Been thanked: 22 times

Re: 80 knots on a foilkite

Postby joriws » Wed Nov 20, 2019 4:33 pm

Not wow, that was downhill assisted run, not kite powered only run

kitexpert
Very Frequent Poster
Posts: 807
Joined: Sun Aug 09, 2015 11:20 pm
Kiting since: 2003
Gear: many kites, also diy
Brand Affiliation: None
Has thanked: 7 times
Been thanked: 14 times

Re: 80 knots on a foilkite

Postby kitexpert » Wed Nov 20, 2019 5:27 pm

RedSky wrote:
Wed Nov 20, 2019 4:48 am

If you want to go fast then use a small kite in very high wind. I don't know much about sailing on water but I imagine that using a hydrofoil design and two small kites in very high wind might work.
One small kite won't be enough and a larger kite has too much drag.
This is incorrect, two small kites are worse than one bigger and very probably even more difficult to handle. Size does not affect a lot for efficiency (L/D ratio), or if you want to be precise bigger kite works with higher RE number and is more efficient. Stacking kites is quite a lot like biplane airplanes or even worse triplanes, they lose for efficiency.

User avatar
Bille
Very Frequent Poster
Posts: 3424
Joined: Sun Sep 04, 2011 5:37 pm
Kiting since: 2003
Local Beach: Lake Mohave
Gear: Ozone Edge
Brand Affiliation: Barz Optics
Jaybar Dynabar V7
Has thanked: 29 times
Been thanked: 29 times

Re: 80 knots on a foilkite

Postby Bille » Wed Nov 20, 2019 7:13 pm

joriws wrote:
Wed Nov 20, 2019 4:33 pm
Not wow, that was downhill assisted run, not kite powered only run
THAT changes things ; not a record for pure kite-power .
Still ---- Fast as Hell though !!!
It would be like calming a world record for highest jump, off the
water,with a kite ; when you used ridge-lift from a cliff, to do it.
Nope -- it don't count.

Sailrocket has a LOT of parasitic-drag , that could be addressed
in order to get some more speed.
That sailrocket design, only went in ONE direction ; i'll be
impressed, when it can go that speed, in Both directions.

The Greenbird landsailer, did 126.1-mph (World Record) ; and it
could go Both directions .


Bille


Return to “Foil Kites”

Who is online

Users browsing this forum: No registered users and 2 guests