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Old 10-02-2017, 02:24 PM
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mojo1986 mojo1986 is offline
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Default Repairing Rocket Tubes That Have Zippered Along The Seam

Once in a while you may encounter this type of damage to a favorite bird and, for whatever reason, don't want to repair the damage by shortening the rocket (for example, as in my case, where the rocket is a scale bird). This is an Estes Black Brant III. Happily, there is a technique that can save the day. I'll add the repair steps as I have time.

Incidentally, this damage cannot be reliably repaired by just glueing a 'butt weld' because the insertion of the nose cone exerts a lot of stress on the damaged area and will inevitably re-open the tear.
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Old 10-02-2017, 02:35 PM
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Step 1:

Cut a short length of tube that's the same diameter as the rocket tube, then slit it lengthwise. Tape it firmly around the damaged area making sure that the edges of the tear fit tightly together. You may want to provide internal support when you do this ( you can just use the nose cone ).
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Old 10-02-2017, 04:39 PM
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Step 2:

I removed the old shock cord mount (the shock cord was broken anyway) to make more room for reinforcing the tube. After that I sanded the inside of the tube to give a good clean area for glue adhesion.
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Old 10-02-2017, 04:44 PM
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Here are the materials needed for the rest of the job...........tissue paper, thin CA and one of those ladies' nail sanding sticks.
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Old 10-02-2017, 04:56 PM
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Step 3:

Next I glued a layer of tissue paper on the inside of the tube using thin CA. I found the easiest way to do this was to cut manageable sections of the tissue paper and then get it situated and laying flat inside the tube over the damage area. Then I ran a drop of the CA down the tube along one edge of the paper. If I was satisfied with the alignment I used a piece of small dowel to wipe away the excess glue. As soon as the glue was dry I lifted the portion of the tissue paper that was not yet glued down and ran some CA under it, then laid the tissue paper down and eliminated any bubbles under the paper. Depending on the size of the damage area it may take two or more sections of paper installed in this manner to do the repair. It's hard to see the tissue paper repair in my photo because it essentially turned clear with the CA under it (I used white paper).
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Old 10-02-2017, 05:01 PM
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After that I sanded the inside of the tube and the portion of the nose cone that fits into the tube. This latter job is the only part of the procedure that I found took particular care. You need to sand the cone enough for a smooth fit in the tube but must be careful not to sand down the shoulder of the cone. This is where the sanding sticks come in handy.
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Old 10-02-2017, 05:03 PM
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Et voila! A rocket that still looks stand-off good and will fly again. The tube is good and strong. I expect many flights.


Joe
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Old 10-12-2017, 03:54 AM
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Thank you for posting this! A "complementary repair" (since you had to remove the shock cord anchor; I devised the following repair [my friend Dr. Roy F. Houchin tested it and wrote the article] with scale models in mind, too) is a removable shock cord anchor (see: http://www.oldrocketforum.com/showt...able+shock+cord and http://www.apogeerockets.com/educat...wsletter231.pdf ). There is no reason why body tubes cannot be kept flight-worthy indefinitely.
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