http://www.oceanrodeo.com/kiting/images/rise/RiseVenturiExplained2.swf

so ocean rodeo obviously have not herd of the slot fin or seen a few experimental sails from the old speed sailing era, guess what they didn't work, and i think the plane designers of the last say, 60 years would have thought of this and be using it now. another gimick for the kite would to spend there money on..

before you are allowed to purchase and use this kite, you must be prepared to wear this outfit.

some kind of super hero flying fetish thing I suspect....?

kitecrazzzy said...

if that was true then wouldnt the normal kite pull most when at the top of the window?
truth is the venturi effect does not happen any more with 08 kites unless you want it to and I personally use all the kite phenomenons to my advantage like reverse launching and pivot turns and would be uynhappy for my kite to not be able to do that as im not a kook who needs a kite that flys itself.

...HUH?

wheather or not that idea works on kites i dont care but , they do use slotted flaps on planes like the 747 and a whole variety of other types of planes.
they let the wing take on a higher angle of attack without stalling on takeoff and landing.

just like in the picture as the wing reaches critical AOA usually about 16 degrees the boundary layer breaks away from the surface of the wing and it stalls ,
so what the slot does is to keep laminar flow all the way along the chord of the wing at high angles of attack and low speeds usually the flow breaks away further down the chord first which is why the slots are at the back!

so yes!! aircraft designers have been and will still be using this technology for some time.


and WTF is with the outfit ? who would seriously wear such a thing

A properly designed slot delays the point at which flow separation migrates forward (the beginning of stall). This is due to the slot "refreshing" the boundary layer and reducing the adverse pressure gradient over that last section- so the boundary layer doesnt have to "push as hard" for "as far". Result is higher angles of attack before the lift breaks down and the drag slope increases.

Flow separation can occur in either laminar flow or turbulent flow conditions. Trailing edge separation will be turbulent flow separation for typical foils.

For this to be useful, the slot shape is critical, since flow separation can occur immediately if the downstream side of the slot is made too sharp.

So if its not done right, the result will be less lift and more drag, giving no advantage at higher angles of attack (where its meant to work) compared to a partially stalled regular section.

The main benefit of this technology in aircrafts is to significantly increase the wing camber with highly angled flaps. This increases the amount of lift for a given angle of attack. Without the slots, the separated flow would render the flaps significantly less effective.

If it aint done right...

jp747 said...

in the near future one of the better sail makers would have vented slots with sort of springs to vent out 1-2sec. gusts so the rider maintains posistion and not lose speed...does that seem logical

Isn't that what twist does?
The vents they put in wings are there to stop stalling at slow speeds and high angles of attack. In a sail they might help your pumping and low end grunt I would expect.

I have a slotted fin and i love it. I use it on Botany Bay in big southerlies when the fin spends as much time out of the water as it does in. This thing recovers from spin out almost before it happens.

Maybe the problems in the past with vented sails has been the implementation of the theory, rather than the theory itself?

Sure twisting sails are designed to absorb gusts, but doesn't mean that it can't be done another way. Maybe there could also be a reduction of turbulence or drag that could push past that 50knot barrier?

Anyway, I think we should embrace any innovative ideas (even when they are a rehash of old ideas). Progression of technology is about science, but also about experimentation and just plain old dumb luck. Sometimes new concepts are discovered by accident by doing something "stupid".

evlPanda said...



Yup, have been wondering that about the resurgence/reintroduction of twin fins, and the obvious lack of thrusters. Is there a technical reason why thrusters (3 fins) don't work on windsurfers or has it just been poor/unlucky implementation?

I think that Mr. Stone (of SSD) might disagree with you

why isn't there any move to put some drag reduction devices on the top if the board itself..everything i bet was tested underneath but on top am sure just in 20kts of speed there is wind drag in front, mastbase,footstraps and etc..nobody ever tried putting some sort of spoilers to push the front end down..however, not all of this was thought for wave riding and freestyle..it'd be