Laminating FTC

Robert Youens

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.

My pressure test vessel. It began to leak at the bulkheads between 190 and 200 psi.

Very light weight Kevlar Veil (Mat).

Elmer's ProBond

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.

Right:  the fins attached to the Kevlar laminated FTC.

Right:  The altimeter mounted in advance of the bulkhead. The altimeter is attached to the cone with screws and sits on the bulkhead.

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.

This is a close up of the wrapping 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 wrapping I rubbed ProBond in to the fiber. I wiped of any extra ProBond to reduce weight and foaming.

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 culprit of the leaks at the bulkhead on the Kevlar test vessel.