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Laminating FTC
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Robert
Youens
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I feel that I have pushed the limit of FTC tubing. I have produced 900 G launches with 130 PSI CO2. I have found that FTC fails at between 130 and 150 PSI. The next obvious step was to laminate it. Since I found no epoxy resin that would stick to FTC very well, I have been testing ProBond. ProBond is a very low viscosity polyurethane glue. I found that if it is applied sparingly it wets cloth and produces little foaming. The bond between cloth, polyurethane and FTC has not failed during my tests. I take some satisfaction in this because I was told by many that it wouldn't work, and some just laughed at the idea. I feel that it is just thier problem for not being able to think outside of the box.
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My pressure test vessel. It began to leak at the bulkheads between 190 and 200 psi.
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Very light weight Kevlar Veil (Mat).
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Elmer's
ProBond
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Left: My first attempt at laminating with kevlar and ProBond on a full length FTC rocket. It was a little messy and the explanation of the support mechanism I developed for the process would be too lengthy for this page. I did not take pictures of the process since I did it by myself and my fingers were covered in glue.
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Right: the fins attached to the kevlar laminated FTC.
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Right: The altimeter mounted in advance of the bulkhead. The altimeter is attached to the cone with screws and sits on the bulkhead.
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I am now test Spectra fiber. Spectra can be purchased at Walmart and most fishing stores under the name Spiderline. I have been told that spectra is about 4 time stronger than an equal weight of kevlar and is about half the density of kevlar.
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This is a close up of the wraping technique I used. I used a technique that I learned while serving the end of bow strings. The technique allows a very tight wrap and requires no knots. After wraping I rubbed ProBond in to the fiber. I wiped of any extra ProBond to reduce weight and foaming.
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My completed Spectra test vessel. I am going to give it about a week to dry and will pressure test then. I hope that it will hold over 200 psi. Since Spectra has virtually no stretch and the spectra is wrapped tightly, I feel that this should reduce stretching which is the likely culpret of the leaks at the bulkhead on the Kevlar test vessel.
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