How many layers of fiberglass cloth (and cloth weight)?

[prfesser]

Hello, looking for data to provide to the uni team I'm mentoring:

For those of you who have made all-glass tubes using cloth: (A) how many layers of cloth did you use? (B) what was the weight of the cloth? Did you use different weights? (C) what kind of stress was expected on the tube (i.e. what sort of rocket were you building the tube for)?

Best -- Terry

 

[tfish]

I've built some all glass tubes/rockets. I have no real scientific data on what I've done. Other then what I've learned. I built one rocket years ago to prove that a hand layed all fiberglass rocket..using thinned out 'boat epoxy' could hold up. It flew to 37K at mach 2.2

Like plywood...(for a given thickness) ....the more layers there are the stronger it will be.
You can use the glasses 'mil thickness' to help guess how many layers you might need to get a certain layup thickness. (usually same as our normal rocket body tube wall thickness)
When I do STEM with local high school we layup short 'test' pieces prior to committing to actual tube.
One continuous wrap seems best.
A wrap or more of mylar over the mandrel helps greatly is removing things from the mandrel. They can also be used to make a mandrel slightly bigger. If using a motor case as a mandrel..be aware not all motor cases are the exact same diameter.
Do not tape the mylar to the mandrel!

here is a thread on the above rocket https://www.rocketryforum.com/threads/my-next-project.19534/#post-174464



Tony

 

[SDramstad]

I use 3 to 5 layers of 5.8 oz E glass. More layers for bigger tubes or higher power. Use west epoxy and a Mylar sheet around the mandrel and peal ply on the outside. Have never had a structural failure that started a problem. I did have a 4 inch tube go sideways when it went transonic and that came apart but what wouldn’t have at that point?

steve

 

[prfesser]

Thanks Tony, that is excellent information!