Ozone edge V8 stitching on leading edge

[Hannay]

Hi, what is OP? Original Post?

We pumped with our new hand pump until around 12 PSI, the tube started bulging around the seams about 10 or 11 PSI (we bought an expensive gauge, not the pump one). I could not pump beyond 12 PSI, it was too hard to get any more pressure in with the pump so I switched to a compressor. The stitching started to rip through the material about 17 PSI and then popped at 21 PSI with a huge bang. 7 PSI is solid, 5 PSI also feels solid but not quite enough to ride. No kites should be pumped beyond 7 PSI in our opinion, there is no need. Especially for the bigger kites that have larger LE diameters.

It was an interesting test instigated here and good to know that our materials are well within the calculations and the practice. As we say in the above post we will continue to work on better materials and methods as we always have done, it is our bread and butter. Cheers Iain

[Kamikuza]

As badly bulging as in those pics?

[Puetz]

... just wondering:

If a kite is pumped up to 7 psi, does the pressure go up, albeit for a short period, if you bend the kite in particular the LE ie dropping the kite in the water, relaunching etc and therefore excess pressure on the LE stitching?

Is it possible for pressure to spike up if you crash the kite and will it reach the stitch splitting pressures ie when you tomahawk the kite into water?

Is it better to leave the locking off clamps on the one pump 'open' to let the air pressure distribute to not only the LE but to struts or will that make no difference?

Cheers,

Robbie

[teabaggin]

Hannay , how many times do I have to state it that " The stitching of the closure seam failed just past where the reinforced layer of material finished " . Just as I thought , there is no way that your going to post results of tests on ( the closure seam where there is no reinforced layer of teijin ) . All your 5 samples have the reinforced layer of material so you have shown results of a test where the stitching hasn't failed on my kite. Ill ask again please show the samples of the tests on the stitching of the closure seam just outside of where the layer of reinforcing finishes. Just one more question Iain Hannay , if you stand by what you have stated here

The feedback from our customers on this forum has further inspired us. We now have the lab testing many variations of the leading edge closing seam in pursuit of even better results. We hope to further improve the durability of the kites wherever possible.

Future manufacture.

We have the ability to implement any new construction techniques that we see of benefit to the performance of the kite or the user with our own production facility. However like everything it must be well tested before implementation.

Finally

We will continue to listen to you, our customers, with the goal of bringing you great performing products.

Many thanks Team Ozone.

WHY HAVE I BEEN TREATED LIKE SHIT

[KITEMOBILE]

Could you tell me where is it stated that your EDGE should be at 7 psi.........even your dealers in Canada are telling us that Ozone's are always inflated at 8psi

[marlboroughman]

WHY HAVE I BEEN TREATED LIKE SHIT

Because this problem is too big. No company will exchange their whole annual production. If they do it for you they have to do it for everyone.

Since when Ozone is using Teijin Dacron on the leading edge? They used to use Dimensions Polyant.
The bottom line is there were no problems with previous Dacron and stitching method.

[Kamikuza]

WHY HAVE I BEEN TREATED LIKE SHIT

Because this problem is too big. No company will exchange their whole annual production. If they do it for you they have to do it for everyone.

Since when Ozone is using Teijin Dacron on the leading edge? They used to use Dimensions Polyant.
The bottom line is there were no problems with previous Dacron and stitching method.

Thought they said 0.1%?

[Kozzie]

teabaggin why do you over inflate your kites?

[Greenarrowz]

Thankyou for the test results.
In my engineering opinion the results are very accurate.
Only one problem...
They are test results from the re- enforced section of the leading edge .

In any case these results can be divided by 50% due to the use of only 1 stitch on the failing segments of the v8,s leading edge... as opposed to the dual stitching clearly visible in the test photos Ozone provided here. Which i copied for personal record.

Ozone test shows bulging of re enforced section at 10 -11 psi....
Subtract 50 % due to 1 row stitching on non re enforced segment
Single stitch non re enforced = now 5 - 5.5 psi bulging

This is starting to make sense.

Next test states the stitching starts to rip through the material at 17 psi
Divided the result by 50% and you have the reported
Damage occuring at approx....... 8.5 psi...

Only 8.5 PSI

So if you pump your edge to factory 7 psi...
a mild increase in preasure can take it to 8.5 psi quite easily and into what Ozone deems a over inflated psi .

Furthermore Ozone deems 5 psi not quite enough for the edge V8.

And 7 psi seems to be in a potential danger zone.

My conclusion is the 13m edge V8 has an inherent fault in the design focusing around the non re enforced sections that follow outward directly after the re enforced segments.
Its very clear to me the re enforced segments do their job well...... and we can see what occurs when they are
deleted.

Your thoughts Hannay.

[Hannay]

Hi Greenarrowz, the area where the double stitching stops is a much smaller diameter and so the hoop stress is completely different, check the graph please. These measurements have been taken from the widest point in the center of the kite as a reference to what would be the biggest hoop stress.

We have seen that the stitching and leading edges are not breaking, Teabaggins kite has not completely failed, it has started to fail but the kite it still intact. We saw this happening when we over inflated the kite, the kite failed at 21 PSI, as expected at the widest point of the LE where the hoop stress is by far the biggest.

Thanks for all the interest in this topic, all of our customer feedback is taken seriously and is quantified.