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Do kites fly better with strut inflation valves closed on a one pump system? It really seems that my Ozone Zephyr shows a difference when flying between all valves open and all valves closed. It seems to go upwind better with the strut valves closed. Maybe if the valves are all open the air in the bladders is moving around from chamber to chamber too much, and this causes some losses?

alden wrote:Do kites fly better with strut inflation valves closed on a one pump system? It really seems that my Ozone Zephyr shows a difference when flying between all valves open and all valves closed. It seems to go upwind better with the strut valves closed. Maybe if the valves are all open the air in the bladders is moving around from chamber to chamber too much, and this causes some losses?

I can't say I have ever noticed a difference, but I did hear that once...if you isolate all the chambers they can all keep constant pressure as varying forces are applied to different areas of the kite. Don't know if it's true or not.

I usually close them off for safety (I won't lose my entire life raft in a catastrophic failure) and because it's a great way to detect a leak early at the end of a session... When you open them all up if you hear a "tsst" indicating the pressure is different..somebody has a leak.

never noticed a difference. You need more than one sample, because wind gradients etc. Try flying it open, then later fly it closed and repeat, be better if you get someone else to open or close the valves so it's a blind experiment

I've noticed a difference - I use a gauge and always pump to the same pressure. I was using an early OR Rise and it was real clear that it was stalling on the way out of turns and that the LE was getting way more bent than normal. It took a lot of bar throw to get the stalls to reverse. When I was deflating it I noticed that I had forgot to close out the struts. Not as good as a double blind experiment but it was noticable to me that it was flying not as well as normal.

Also, safety.

..and do it for at least 30 trials at a minimum so that you can generate a strong P-value with a proper power and effect size...

Why should it make a difference ?

Thinking, and can not see why...
That does not mean it is not correct though.

In my mind (NOT experience), it would not make any difference whatsoever.

But would like to hear why it should ?

Interesting...

I never ever close the valves - and have removed the valves on some of the big kitesizes, and they are way faster and easier to pack down.

Havent removed them in the small sizes, because they are fast to pack down anyways, AND for the occasional use when out in rainy weather, and I pack the kite halfways down with struts inflated - so I can keep it from getting "ugly" and mouldy/colour smeared, by drying it back home standing on the struts

Still, I never close the valves when on the water - so only used the rare times the kite is rain wet when going ashore and packing down.

Peter

It absolutely will make a difference. If all the bladders are openly connected to each other, then any extra force applied on any bladder will be allowed to deform more, because there's more space for the displaced air to escape to. To prove the point, imagine a gigantic/infinitely sized kite with a normal-sized strut, with the valve open. You'd be able to empty the strut of air completely just by squeezing it. With the valve pinched off, you'd never be able to do that without bursting the bladder.

The question comes down to whether or not its noticeable in an everyday situation. I did have one session where I thought the kite felt sluggish, and then discovered later that I forgot to pinch the valves, but that may have been a fluke.

I seriously doubt it. There is very little squeezing pressure on a strut bladder. There is bending for on bladders though. Is it any harder to bend a strut or LE with the valves closed by hand? No, didnt think so. Air compresses very easily, especially at the pressures our kites hold. A deformation of a bladder such as you would have noticable in flight would require very little compression force on the air inside. Those clips only serve to prevent complete deflation in case of a puncture.

I always pinch struts. I have some launches where I launch the kite and have to kite a mile away to the riding area. Needless to say, it is a long damn swim back if you as so much as pop a valve and you have a bag of soggy laundry. Just one strut pinched helps a ton. By the way, when I pinch one strut, I will pinch either the left or the right. If the theory is correct, then the kite will turn faster in the pinched direction. Nope. Still turns the same.

But I could be wrong. This is one of those things we are going to be able to argue about all day because everyone is too lazy to do an actual controlled experiment. One experiment is have your launcher randomly pinch either the left or right strut, launch and then you try to guess which strut is pinched. I bet you can't do better than random.

I notice a difference on the fuels with them closed kite flys more firm for sure. Either way as stated above always close them so if needed your life raft doesn't deflate. lol