## Re: [ksurfschool] Power/Depower Question

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• ... Jim, You ve got it backwards. The lines that run through the center of the bar go to the front connection points on the kite. Aside from having an
Message 1 of 2 , Nov 3, 2002
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>trying to visualize the control of 4-line kites. As I understand it
>the leading edges are attached to the bar ends, and the trailing
>edges are fed through the bar to the spreader bar, so pulling in on
>the bar would decrease the angle of attack of the wing, and it would
>fly faster. Letting up on the bar would increase the angle of
>attack, giving more lift but making kite slower.

Jim,

You've got it backwards. The lines that run through the center of the bar
go to the front connection points on the kite. Aside from having an
adjustable strap to change the line length when you are on the water, these
lines are effectively fixed length (relative to the rear lines.) The lines
on the ends of the bar go to the rear connection points. When you pull on
the bar, you are increasing the angle of attack and therefore the force
generated by the kite. When you sheet out with the bar, you decrease the
angle of attack and therefore decrease the force generated.

>Sorry, but I come
>from a paragliding background, and am trying to relate it to what I
>know already. What is "power" in kiteboarding, in or out, speed or
>lift, or am I off-base in my little analysis? Keeping in mind that
>the only dumb question is the one not asked, could someone please
>explain?

Keep it simple: power is the pull that the kite exerts on you. Where the
kite is in the window determines the combination of directional forces that
act upon you. If the kite is straight overhead, it can only generate lift.
If it is at the edge of the window close to the ground, it can only
generate force parallel to the ground and perpendicular to the wind. If it
is straight downwind (which does not occur on a static basis unless you are
boarding straight downwind, otherwise it happens only when flying the kite
through the window) the kite will generate force parallel to the ground and
parallel to the wind direction. This link (provided earlier on the group)
does a good job explaining the physics of kite flying:

http://www.seattleairgear.com/kp101.htm

Just to complicate things further, the faster you are traveling over the
water, the greater the apparent wind acting on the kite and therefore the
power generated by the kite. The edge of the window therefore moves
downwind as you travel faster across the water. So, if the wind is blowing
15mph and you are moving across the water at 15mph, the apparent wind
acting on the kite is a combination of the two. This is why if you get
going too fast, the kite will fly farther down the wind window and will
generate more and more power. The only way to overcome the "downwind death
run" is to slow yourself down and get the kite to fly closer to the edge of
the window. You does this by edging really hard on the rear upwind corner
of the board.

>And while I've got your undivided attention, what are the pros and
>cons of having a quiver composed of different brands of kites? I'm
>looking on Iwind and Ebay for kite deals. What would be the problems
>if I ended up with a Naish 3.5, a Cabrinha Blacktip, and a Slingshot,
>of different sizes, for example.

Pro: Variety is the spice of life. You get to see how different brands of
kite fly. But I would rent to accomplish this.

Con: How kites are measured varies from manufacturer to manufacturer. If
you have a mixed quiver, you could end up with kites that are very similar
in terms of the power they generate, even though they may have very
different sizing numbers. I would recommend sticking with one brand of kite.

If you watch iWindurf.com carefully you can find reasonable deals. I've
gotten some decent lightly-used equipment there. However, from my
experience, the stuff on eBay tends to be either pretty old (two to three
years) and beat up, or new and expensive. I watch the two forums pretty
closely either way. I did get a Cabrinha Spoiler 150 board with NSI Tantrum
bindings (new the setup is \$870) on eBay for \$199 on a Buy It Now because
the seller did not know what he had and I was the first person to look at
the auction. Luck happens, every now and then...

:-)

Chris