How to fix a crimped tube?

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Well-Known Member
Jan 7, 2004
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I have a rocket that was damaged on it's last recovery. It's an RHR2003. The lowest body tube section (motor tube) is crimped just above the thrust ring. It won't fly like this and I was planning to just cut off the lower section of this rocket and use it like that with only the foreward fins.

I also thought that I could probably cut the tube at the crimp and stick a coupler or a piece of an 18mm motor tube in there to stiffen the tube.

I'm not sure what to do about this. Any suggestions? Both options have pros and cons so I thought I would put it out to everyone for tips.


A second photo of the whole rocket. I tried to get a close-up of the crimp but it just blurs with my camera.

What you said: insert a coupler.

You might want to either cut out and replace the crimped section or else cover it with a splint made of a piece of body tube cut lengthwise. Of course the former means two couplers or a long piece of coupler stock, and latter means redoing the finish.
While I have found that an internal coupler works the best, another method to try is to poke a series of holes along the crimp with a straight pin, wick in some thin CA and hold the tube straight until the CA cures. This, of course only works with paper
body tubes.

A couple years ago I sat on my favorite BBII and crimped it right at a seam. When I got it home I scraped the paint down to the split/crimp. Straightened the crimped tube as best I could from the inside as well as the outside. I exposed enough of the split/crimped area area to drizzle some thin CA onto the area. I got the CA on the inside as well. The repair was really tough after the CA dried. I filled the repaired area with FnF, primed and repainted the rocket. It had many more flights after that repair.

If the crimp is bad enough it would probably be the best to cut it off and add a coupler like the good advice given by the others.
I have to wonder if your basic design has a weak spot in that reduced-diameter lower body tube.
These comments are all purely qualitative, and based on a couple small images to boot, so take 'em with a grain of salt--
If the rocket lands by parachute and the lower portion (as shown) is the first to touch the ground, then the weight of the upper portion is going to act to 'squish' that lower tube again. Having a section of reduced-diam between the 'heavy' part of your rocket and the ground will effectively create a weak 'zone' where you are kind of begging for loads to be concentrated. If you add a coupler, you will obviously reinforce the area in immediate contact with the coupler but you are also likely (IMHO) to get another crimp just ahead of or behind the coupler.
I would suggest using another length of BT to reinforce the full length of that lower section from the inside. Cut an appropriate length and remove a slot from the side (maybe 1/8 inch wide?) so that your second tube will compress and fit inside the existing one. Swab with plenty of glue before inserting. You might even be able to add this through the existing motor mount, or through the front of the rocket (without cutting into the lower BT).
You will of course need to re-check stability after adding reinforcement (whether you use a coupler or a second BT liner like I suggested) to the rear end.