Contact   Imprint   Advertising   Guidelines

current LEI designs

forum for kitesurfers

User avatar
Frequent Poster
Posts: 310
Joined: Fri Aug 30, 2013 3:40 pm
Kiting since: 2011
Local Beach: Plumb Beach
Favorite Beaches: Cabarete
Gear: Ozone, Core
Brand Affiliation: None

current LEI designs

Postby deniska » Fri Jul 11, 2014 3:46 pm

Sorry if I ask something stupid (I know nothing about aerodynamics) but are there any advantages for having the canopy on top of LE/struts vs the other way around (ie canopy on the bottom)?
To me it seems that the bottom side of the kite does all the work, so removing those air pockets on the bottom may result in better aerodynamic design.

User avatar
Frequent Poster
Posts: 242
Joined: Tue Jan 08, 2013 11:39 pm
Kiting since: 2012
Local Beach: Ft Lauderdale
Miami beach
Style: Wakestyle, Freestyle
Gear: Best

Re: current LEI designs

Postby jats2k9 » Fri Jul 11, 2014 4:03 pm

That would be like turning upside down an airplane wing. Think about. You will see what I mean.

Very Frequent Poster
Posts: 3764
Joined: Sun Jul 24, 2005 6:39 pm

Re: current LEI designs

Postby ronnie » Fri Jul 11, 2014 4:38 pm

Its the upper surface that is the important one. A lower pressure area is created by the flow of the air on the top of the surface. Its not really based on the wind pushing on the lower inside surface as such except if the wing is backstalled.

They put tell-tails on the upper surface of sails to help keep the flow laminar. They do also have tell-tails on the lower surface, but the upper one is the most important one for getting drive from the sail.

User avatar
Very Frequent Poster
Posts: 4998
Joined: Fri Jul 16, 2010 6:27 am
Kiting since: 2010
Local Beach: ford lake Michigan
Gear: slingshot liquid force wainman pansh naish north cwb burton

Re: current LEI designs

Postby edt » Fri Jul 11, 2014 4:47 pm

the faster air goes the more drag it creates this is proportional to the velocity squared. If you look at a wing, the air has to move in an arc around the outside of the top of the wing, but underneath the wing it can go straight across, thus the velocity across the top of these surfaces is in an arc you can calculate it with some radius times pi times the arc and the width, while the velocity under the kite is simply the width of the kite.

The struts cause a lot of drag so you must put them underneath the wing to reduce drag.

Good idea though! It is this sort of thinking outside the box that can lead to new and better wing designs.

When the kite is in the power zone you do need the kite to catch all the air and these struts get in the way. However most of the time the kite is not power looping instead it is at about 45 with most of the flow going on top of the wing.

Notice aaron hadlow often would get his kites designed to remove the middle strut for just this reason so when he popped off the water or kitelooped the kite would generate more power.

There has been plenty of experimentation removing all or most of the struts with the cloud or liquid force solo.

In my opinion you don't practically gain any upwind capabilities by removing the struts, what you do gain is quicker kite to pump up and better packdown.

User avatar
Very Frequent Poster
Posts: 5633
Joined: Fri Jan 09, 2009 4:49 am
Local Beach: Sabae Beach
Favorite Beaches: Ol' Stinky
Gear: This, that, the other

Re: current LEI designs

Postby Kamikuza » Thu Jul 17, 2014 8:01 am

Slingshot split-strut... best solution?

Very Frequent Poster
Posts: 3284
Joined: Thu Jun 05, 2003 3:37 am

Re: current LEI designs

Postby BWD » Thu Jul 17, 2014 1:15 pm

The intrados (bottom side) matters more than some think!
To say it's the top surface only would be a gross oversimplification.
It's true the low pressure top side is sensitive to disturbance of air flow (which is already separating anyway over most of the canopy).
But the bottom is important, and especially in the "shoulders" of the kite.
Having this area clear of struts gives a power advantage. This is seen with 3 strut (and strutless) more than with 4 strut designs.
Pressure is developed over the bottom of the kite. You can tell that when a kite is crashed LE down and still pulling you out to sea! The top of the kite is more about controlling drag, from my POV. There is more than one way to look at it though, for sure!
Look up unconventional airplanes and airfoils, it's interesting...

Very Frequent Poster
Posts: 684
Joined: Tue Jun 19, 2012 10:39 pm
Kiting since: 2011
Local Beach: Netherlands. Maasvlakte, Slufter, Scheveningen, Domburg, Rilland, Brouwersdam, Ouddorp, Binnenschelde, Vrouwenpolder, Oostvoorne, Rockanje, Grevelingen, Borssele.
Style: Freeride, freestyle, wave.
Gear: Switch Helium V1 18m Element V3 13m-7m V4 9m-5m Legacy V1 10m-14m Slingshot Fuel 2005
Switch MJComp V2 136x41.5 Firewire Hellrazor 6.1 timbertek Shinn Shinnster Nobile 555 125x38
Brand Affiliation: None

Re: current LEI designs

Postby Faxie » Thu Jul 17, 2014 11:06 pm

Lots of bollocks here....

Just think of 1 thing: A plane can fly upside down :thumb:

You can fill the rest in.

Very Frequent Poster
Posts: 778
Joined: Mon Jun 28, 2010 6:58 pm
Kiting since: 2008
Local Beach: Portugal
Style: Freeriding
Brand Affiliation: None

Re: current LEI designs

Postby Tiago1973 » Thu Jul 17, 2014 11:25 pm

what´s wrong with struts on the bottom? i think they look good

User avatar
Medium Poster
Posts: 165
Joined: Thu Aug 24, 2006 2:16 am
Kiting since: 2003
Location: TO

Re: current LEI designs

Postby william_rx7 » Thu Jul 17, 2014 11:49 pm

No struts = No drag and No weight...


User avatar
Frequent Poster
Posts: 326
Joined: Fri May 17, 2013 4:43 am
Kiting since: 2008
Brand Affiliation: None

Re: current LEI designs

Postby cleepa » Fri Jul 18, 2014 3:21 am

No struts = No drag and No weight...
Amen to that!

Return to “Kitesurfing”

Who is online

Users browsing this forum: jjm, SaltWaterDog and 12 guests