Question, Can you go faster than the wind is blowing in a buggy? You know if the wind is blowing 20 mph is that as fast as you can go is 20? If not how does that work? I know it will have a little to do with terrian and buggy Can you see what I am getting at?:puzzled:

Of course you can. Can't say I could explain in physics, but as the buggy picks up momentum, the kite is forced to keep up, and continues to stay powered (as longs as your keeping the kite in the wind window, and your traveling somewhere around 90 degrees to the window.) so you are continually gaining speed.

Maybe someone will have a really cool physics filled reply to help out.

I can't really explain the physics of it myself either, but typically one can triple the wind speed.

Also the faster a foil travels the more lift/pull you produce. So if you get up to 20mph the foil produces morel lift/pull so you can get to 25 then at 25 you can get to 30. Becuse of air resistance eventually you reach a sort of "terminal velocity" much like in skydiving. That happens to fall right about at 3x the wind speed. Yahh.....I'm a bit of a science geek.

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Originally posted by Sthrasher38 Question, Can you go faster than the wind is blowing in a buggy? You know if the wind is blowing 20 mph is that as fast as you can go is 20? If not how does that work? I know it will have a little to do with terrian and buggy Can you see what I am getting at?:puzzled:

As the buggy gains speed, the wind the kite "feels" is a combination of 2 sources; the wind, and the buggy's movement. These two vectors add up, causing the kite to pull more. So the buggy moves faster, the kite feels more wind, etc. The wind window for the kite will change due to this.

I had known this and buggied for 5 years before I started kitesurfing in 1999. But kitesurfing really made it apparent, as you get this out of control feeling going downwind, trying to edge against the kite. Doesn't happen very much anymore, as you learn to not let yourself get going to fast at particular angles to the wind.

In the buggy, you will watch the kite's window change with the direction the buggy is moving. Going really fast on a downwind speed run, you can watch the kite sink further and further back into, what would be, the other side of the window.

Steve Bateman

Yeah...about 2.5 times the wind speed is the rule of thumb, but can depend on quite a few factors.

Thanks guys!

You can do a little vector diagram to see how the apparent wind that you and the kite feel increases to be greater than the true wind speed and even the buggy speed. The theoretical edge of the window is always 90 degrees to the apparent wind and in this example, I assume our kite can get within 15 degrees of dead into the apparent wind...

http://www.coastalwindsports.com/BuggyVector22.jpg

Here the wind speed is 10, the buggy is doing 22 and the hypotenuse of the triangle indictes that the apparent wind is 24.
What happens is, as you accelerate, the source of the apparent wind moves forward, and since the wind window is always dead downwind of the apparent wind, the window moves from the side to more behind you. In this example, supposing an average medium performance recreational kite can get within about 15 degrees of dead into the wind at the edge of the window, we see that we are nearing the 2.5 times limit that Carl/ Popeye quoted. As the buggy speeds up the window moves farther back and the kite cannot get forward of the buggy any more, and an equilibrium is reached.

Race kites can get closer to the wind than 15 degrees for sure, so they can accelerate more before that balance is reached, but I do not have the means to measure or calculate the top end. I would suspect something over 3 times the speed of the wind with an efficent rig and a heavy buggy to hold it down.

BTW, my "15 degrees" is an estmate based on sight lines on the beach and some compass bearings, so it is a squishy number, but you get the idea, anyway.

edit:
in "Stunt Kites II: New Designs, Buggies and Boats" by Servaas Van Der Horst, the author calculated the Lift/Drag ratio of his kites and worked out some polar diagrams indicating maximum speeds as a fuction of wind speeds at various points of sail/ tacking angles. He calculated a max. of something like 2.3 times the speed of the wind on s light broad reach (just downwind of a beam reach).
But this is in the 90's and the kites he was flying were slugs compared to any measure of modern kites.

Seeing ch35s cool ice buggy makes me wonder if the lesser resistance on the ice allows a higher top speed. Your diagram isn't considering drag from the buggy so maybe it is still just a function of apparent wind angle on the kite vs. the angle of the buggy into the wind.

Yeah, if you play with the vector diagrams and extend the apparent wind vector out, the buggy speed vector get real long (faster) real fast with only minor changes. But in a buggy, I think that is where rolling resistance ruins the party.

I don't remember the exact multiple, but I know that ice boats go stupid fast, like 6-7 x wind speed or something. someone else correct me. Ice blades offer little resistance since they are lubicated by water created by the pressure of the blade and the resultant (momentary) heat.