My UL tube project...

[SHigSpeed]

I came home from work tonight to find a box on my porch. Funny, I don't recall ordering any seasoned deli wedge chicken batter recipe frozen potatoes... Hmm...



I especially love this handling caution:



Oh yeah, this is probably my fabric and hardware!

Sure enough, my materials showed up as promised... Kinda...

Fabric-a-palooza!:



The blaze orange is for my tube, the grey is for Jay's super-stealth stupid simple delete-option special.

So why "kinda"? Well according to the distributor, the fabric was supposed to be 58" wide and 60" wide, but what I got instead was 56-1/4" to 56-1/2". Grr! I can work around it, but it limits how long I can extend the pontoons out front if need be.

Anyway, I was eager to start playing around with the material.

First thing I did was rail the iron as I was told to use the cotton/max heat. I folded the fabric over and placed some paper over it to protect and proceeded to iron it. Oops... Either it was too hot (probably) or I missed the corner with the paper (likely).



Here's another, cooler setting weld:




You can see that the press and temp are pretty good as the welded material is flat, not wrinkly or wavy, and some of the urethane coating is squeezing out. Seems right. The backside isn't as crisp a straight line on the weld as I'd like, but I'm not sure what's good and what's not - yet.

So, what am I doing you ask?

What's this?:



Or this?



Yup, I'm building a peel strength testing jig. The fabric is 1.25" wide and the loop on either end are such that I should be putting even stress across the ribbon. The trick is to make sure I hold the screwdriver level and have the loop on the button level as well.



Next I put some water in the bucket, weighed it, suspended it by the test strip and held my breath...




So far so good. That blemish/white area about 3/4 across is just an area of "different" bonding. With the proper edge template I'm confident I can create a nice tight consistent line of weld.

Next:




Good! At this point I should mention that at max normal lung inflation pressure of 2 psi, the seam stress in a 12" round tube would be 12 lbs of peel per inch. On my test strip that'd be 15 lbs. So already, we're beyond "normal" stress on the tube.

More water!!:





Now we're seeing some stress. You can see in the last photo where I've unloaded it some whitening of the seam boundary. I believe that what's happening there is the uneven seam edge is "leveling" itself such that it starts to peel until it reaches a nice straight line of loading, then it's holding. I don't think that this is affecting the ultimate strength of the bond or the air barrier. At this weight, we're simulating 3.8 psi - nearly double normal max lung inflation. Or normal inflation to 2 psi and leaving it in the sun to heat up to 500 degrees above when you inflated it. <lol>

More likely, though, it's modeling inflating at sea level then driving up to 3500'. This is why you should NEVER inflate your tube until you get to where you're going.

BTW, here's a link to a great chart showing what air pressure is doing as you climb. Each psi reduced as you climb is a psi gained inside the tube so be careful!

http://www.engineeringtoolbox.com/air-al...d_462.html

To be continued...
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