Glassing tubes

Re-posting from Techniques...

If I'm going to glass a 38mm body tube for a minimum diameter rocket, what weight cloth should I use? 2 oz? 6 oz? Thanks!

Josh

2 oz. won't do a thing, only provide a better finishing surface over a heavier weight cloth. A couple of wraps of 6 oz. then a 2 oz. if you want easier finishing. Are you glassing over a cardboard or phenolic tube? Plain old cardboard can take just about anything in the 38mm size.

Thanks!

It's LOC tubing. So i'll pick up some 6 oz and 2 oz cloth.

I used a single layer of 3oz on my Cirrus Dart tube (also 38mm MD) when I was learning to glass. It was actually a wrapping paper tube that I found in the basement, but it was the right size to make a Cirrus. It is plenty strong, and probably could have flown without glass. I just wanted to practice on a cheap tube, but it made a very durable rocket (I also glassed the fins t2t).

I put 2 4oz layers and a 1.5oz layer on the booster section of my Tomahawk, and it too seems strong enough (again I only glassed it to make it survive trips to the launch better). The upper tubes have only one 4oz and a 1.5oz because they are meant to be replaceable if they are damaged. The 1.5oz will be really nice to finish.

With LOC tubing you might have to peel a lot off to get to bare paper before you glass it. I probably peeled about half the thickness of the tube for my Onyx off. First there was the white layer, but I had to take some paper with it to get it off cleanly, then there was a waxy layer that I couldn't sand through. After peeling everything the tube was not nearly as stiff and rigid. I put a 3oz layer on and it feels at least as strong as the original tube, but it is a few grams lighter and it matches the OD of the nose cone better.

I would say anything more that 1 wrap of 6oz (plus a light layer for finishing) is overbuilding for 38mm unless you are REALLY going to push this rocket. It all depends on what you want to fly it on. According to PML the Cirrus dart only needs strengthening for a J570, but that will take it 13,000 feet (not something I plan to do with a single-deploy rocket and no tracking).

JJI

If it's LOC tubing, make sure to peel the glassine finish before glassing.

Lay down a nice covering of epoxy and it will absorb like a sponge. Then lay one more down and make it wet & shiny before you apply the fiberglass.

Do I still need to peel the tube if I decide to use a carbon fiber sleeve from Soller?

Originally posted by JJI
Do I still need to peel the tube if I decide to use a carbon fiber sleeve from Soller?

Click to expand...

peel the tube PERIOD! unless you are just going to fill the spiral and paint peel it. It kinda like scudding G10 vs not. Same thing peel it, better bond, don't, it can not soak in good.

Ben

Josh

You have to peel the glassine no matter what fabric you use. This allows the epoxy to bind to the cardboard. Photo below shows how the exposed paper looks after you've removed the glassine seal. One of the functions of the glassine is to keep moisture (epoxy) out.

It takes about 5 minutes. Take a sharp X-acto knife and cut accurately along the seam through the coating, going in a spiral around the body from top to bottom along the seam of the glassine.

Then start peeling and it peels from top to bottom like an orange skin. If some sticks, first try working it from the other direction. Then, just scrape it off with the knife.