Power Kite Forum

Noob closed cell / twinskin question

Statistic - 20-10-2010 at 04:28 PM

Hi all, I've read that closed cell kites such as the HQ Hydra (which I'm currently working with) and Neo may be more prone to bursting a cell in a crash than an open cell foil since there's more pressure built up when the air can't escape. A couple of questions on this:

1. Is it true, and if so are the closed cell kites more delicate to the point where anyone would notice a difference under reasonable usage?

2. Where do the twinskins fit in on this point relative to open and closed cell foils? Are they also more likely to burst / break in a crash due to the way they're constructed? Thanks very much.

indigo_wolf - 20-10-2010 at 05:06 PM

Depends on the closed cell kite.

Flysurfers have blow-out valves on the belly of the canopy to handle sudden increases in cell pressure, like that caused by a nose plant.


On the Peter Lynn Arcs, damage to the spar pockets might be a larger concern....

From the pages of Coastal Wind Sports:

A significant difference however is that we use rounded aluminum end caps, not the plastic inserts with vinyl end caps. As many ARC fliers have found out, if you crash the kite nose down, the plastic tips that hold the shock cord can push in to the tube, and the tube can cut through the vinyl end cap like a cookie cutter and cut the front of the spar pocket. Not ours!! The smooth rounded end-caps (see picture) will stay put and are far less likely to poke through the pocket.



You can use these to replace the carbon fiber sticks used in earlier model ARCs. The weight is the same as the Peter Lynn aluminum sticks. Some people say not to use aluminum because it corrodes, but we don't see this as problem with proper care. After all, you clean your kite, right? Just rinse the sticks with clean water and dry when you rinse your kite an they will last a long time.

A true noseplant where cell damage is going to happen would almost certainly require that the lines were under tension. There are a lot of times you can minimize or avoid damage to the kite in the seconds before impact. The problem is that there's is a lot of mental conditioning that pulling back on anything slows it down (the "Whoa Pony" effect for lack of a better term), unfortunately, with kites that's just a shortcut to terminal velocity.

I was trying to get my girlfriend's cousin to fly one of my foils and he was leery about breaking something. I spent the better half of an hour nose planting the kite with almost no tension on the lines just before impact. The kite was none the worse for wear.

ATB,
Sam

Statistic - 20-10-2010 at 05:18 PM

Great thanks for the thorough response Sam. Very informative, and yes, I agree the key is also as simple as not crashing the kite at speed...

flash - 20-10-2010 at 05:53 PM

start training yourself to let the bar out when it is headed straight at the ground. It is counter intuitive (see Sam's post) that the one thing most people do when they are learning is to 'shrink into themselves'' thus pulling the bar/handles/etc closer to them. Most kites this actually powers up the kite and makes it go faster. Thus making the chance of a blowout higher.

I have a hydra and a neo and I haven't had any blowouts with them, then again I also tend not to crash them straight into the ground fully powered up. At most I crash, and the kite flags out and heads face down into the snow/ground. I have a hydra that I actually use for teaching/demo's and after a year and a half of it being slammed into the ground repeatedly by new people it still hasn't blown out.

If you are worried about this happening to your kite while learning with the Hydra I suggest that you get a piece of electrical tape and open the zipper on the back of the kite about an inch and tape the zipper in place. This essentially creates a 'blowout-valve' in your hydra.

Hope that helps!


ps. fly the kite till its 'inflated' then land it, then apply the tape, a little easier.

acampbell - 21-10-2010 at 07:06 AM

Quote:
Originally posted by flash


If you are worried about this happening to your kite while learning with the Hydra I suggest that you get a piece of electrical tape and open the zipper on the back of the kite about an inch and tape the zipper in place. This essentially creates a 'blowout-valve' in your hydra.

Hope that helps!


ps. fly the kite till its 'inflated' then land it, then apply the tape, a little easier.


Dang, that's clever! (smacks forehead on desk). Could'a had a V-8!

Statistic - 19-11-2010 at 02:40 PM

(delayed response) Flash that's a great idea thanks. I may try that out

PHREERIDER - 19-11-2010 at 04:12 PM

LE slam will pop anybodies toy. twin skins will twist and shear in off angle slams . the verticals seem to release first so kite still flies just "SWOLLEN" at the shear site.

delicate no, got a stack of tubes that won't pump 8/9 ALL down even the new one. got stack of twinskin ready to do it all day long.(like i just did). pop valve= straws in the dirt outs..but time will keep the kite from hitting the ground.

if rupture occurrs, floss and a needle and 15min. and the problem is solved, got some repairs in the 2-3 year range riding fine

they burst due to input and that's far more a human problem

Statistic - 20-11-2010 at 08:54 PM

Thanks Phree. Hear you that the real issue is on the other end of the lines...

Kamikuza - 20-11-2010 at 09:38 PM

Yeah I can concur with the Human Error factor :(