How hard?

[kitelife]

I have a habit of doing the fold test to make sure the wing tips are firm. Last time I used 9psi and flick test the kite jellyfished and didn’t perform like it should. I usually need more than 9 psi.

[nothing2seehere]

The "fold test" is intriguing to me. I have never used it, never known an instructor to teach it, and can't imagine that it's good for your kite or LE bladder. Am I the only one who thinks that the "fold test" forces the kite and LE bladder to do what they are not designed to do?

I've always found that gauges are reliable and easy to use (except on kites that have a one-directional inflate valve like Cabrinha). Otherwise, the ping test works for me.

What do you do at the end of the session if you aren't rolling your kites up? You are going to create a fold in the material then surely?

Its just another test of hoop stress - I know some people who give the LE a spread fingered squeeze to test and that works too. The point is you aren't trying to fold the LE. You are checking to see if it would fold without much effort. Its supposed to be gender/strength independent rather than a worlds strongest man challenge.

Lots of people don't like to use pressure because few manufacturers adjust the pressure to take into account different sizes. The pressure you use in a smaller kite (thinner LE) needs to be higher than in a larger kite (thicker LE) to get the same flying characteristics for the same model.

Haven't tested pressure gauges back to back to see but I do remember testing cycle pressure gauges and seeing 5-10psi differences. I would be surprised if the cheap kite ones are more accurate than those in track pumps. Whether that's enough to make a difference I can't say but I'll tend to inflate to different pressures on a 5C day compared to a 25C day but the hoop stress is generally about the same.

[nothing2seehere]

Dmitri kind of explains the fold/press test to get the hoop stress right in his video here:

http://youtu.be/-KKY0ZRyqDg?t=195

[k2thiago]

I still new in the sport, but I was told to do one of the two tests already mentioned: ping and the folding. However the "folding" that we do is a little different: we pump the kite then try to balance it on one of his wingtips. That way you are not applying external force, it is only the weight of the kite itself, and it should not bend. It does work fine for me, but if is a strong wind day, can be tricky.
Now I've just bought a pump with a gauge, haven't used yet, but I imagine that will work fine.

[FLandOBX]

What do you do at the end of the session if you aren't rolling your kites up? You are going to create a fold in the material then surely?

Yes, I do roll my kite at the end of a session. But I usually remember to deflate the kite before rolling. It's not folding the material that gives me pause; it's folding a fully inflated LE bladder.

Dimitri's video shows a technique that doesn't trouble me at all. Nothing2see, you've described it perfectly here:

" .....you aren't trying to fold the LE. You are checking to see if it would fold without much effort...."

But your earlier description of the "fold test" describes a different technique that I wouldn't want to do on my kites:

"Move to near the wing tip and try and bend the LE. It should resist bending but still fold."

Bottom line is that actually folding a fully inflated LE (i.e., folding the tip of the LE over to the interior LE) puts too much stress on the bladder. I've seen many LE bladders explode with far less stress.

[Hugh2]

I'm lucky to be a feeble 62-year-old, so I pump my kites as hard as I am able! Turns out that is the top of the red region or around 12 PSI ( I think, the pump is in my garage) for 7 and 9m, and top of green range, maybe 9 PSI, for my 12 and 16m, which are also older kites.

I would be afraid of popping a valve a that pressure. But as long as your kites don't explode, why not.

I'll have to check the gauge, but these two smaller kites are Naish Pivots. It would be hard to pop a strut valve on them, they have a strap that holds them, and the main valve is a screw type.

I once launched a 8m Cabrinha Switchblade for Andries Fourie in Cape Town, and he had pumped it rock hard. I asked him about it and he said he did not want even the slightest chance of flex when he did mega loops. I will never do a mega loop, but I'm with him in spirit.

And being under inflated is a real risk. This past season I had someone insist I launch their kite in what I considered to be way under inflated, and indeed he got dragged as it jelly fished around, till I managed to grab his harness and someone else landed it for him.

[badgb21]

A few years ago, you would often launch folks and the bladder would feel quite soft, you'd say something, they'd shrug and off they went.
Of recent years I rarely, if ever feel a soft kite when launching someone.
Suggests information and equipment (pump gauge) has helped.
Anyone else noticed this?

[iriejohn]

A few years ago, you would often launch folks and the bladder would feel quite soft, you'd say something, they'd shrug and off they went.
Of recent years I rarely, if ever feel a soft kite when launching someone.
Suggests information and equipment (pump gauge) has helped.
Anyone else noticed this?

Yes, I've noticed. And if I'm asked to launch a kite which I think is too soft then I say so and refuse.

[nothing2seehere]

What do you do at the end of the session if you aren't rolling your kites up? You are going to create a fold in the material then surely?

Yes, I do roll my kite at the end of a session. But I usually remember to deflate the kite before rolling. It's not folding the material that gives me pause; it's folding a fully inflated LE bladder.

Dimitri's video shows a technique that doesn't trouble me at all. Nothing2see, you've described it perfectly here:

" .....you aren't trying to fold the LE. You are checking to see if it would fold without much effort...."

But your earlier description of the "fold test" describes a different technique that I wouldn't want to do on my kites:

"Move to near the wing tip and try and bend the LE. It should resist bending but still fold."

Bottom line is that actually folding a fully inflated LE (i.e., folding the tip of the LE over to the interior LE) puts too much stress on the bladder. I've seen many LE bladders explode with far less stress.

Ah. Makes sense. I see your point. I probably should have said 'crease' instead of fold - but even that might not have been clear. Its something that's easy to demonstrate but difficult to explain. Probably why pressure gauges are the primary way for most people.

[Hugh2]

I checked the gauge on my yellow Naish pump, one of the newer taller variety, yesterday when pumping my 9m Naish Pivot, and the top of the red zone is indicated as 12 PSI, and that's where I pump it to, and it is as hard as I can get it. Passes both the ping and wingtip fold tests with flying colors.