Fiberglass & Epoxy ???

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Well-Known Member
Jan 18, 2009
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Alright, so now I'm getting paranoid :eek: about whether or not I need a layer of FG on the rocket in the thread linked to here-

So I started doing a bit of looking for information on West Systems epoxies and have some questions.
Which hardener do you guys use?
From the West Systems site I see that the two choices are #s 205 and 206. You guys talk about 24 hour stuff, but they both say "Cure to maximum strength 1 to 4 days", the difference is in pot time and Cure to a Solid State time. I'm guessing that as someone that has never worked with this stuff before, I'd do better with a pot time of 20-25 minutes to give me more time to fix things that may pop up, which is #206.
Is a quart of resin and the .44pt of hardner enough for a 48" 54mm bodytube?
I'm sure that I have other questions, but right now I can't remember them.
Any help will be appreciated,

Ok, first of all a quart of 105 will be plenty and then some. As far as the hardeners go, I have both. I use more 205 in the winter and 206 in the summer do to the temperature ratings of the hardeners. If I’m not laminating I’ll use 205 for building/assembly. You could probably start with a quart of 105 and a can of 206 if you’ll be using it at > 60 deg. If you get to the lower range of the hardeners, let’s say 45 degrees or so on 205 it will have a longer pot life but the opposite is true when the temperature is higher. Also, after mixing the epoxy in a cup I will pour it onto a paper plate to prevent heat build up which will accelerate the cure tremendously. While this rocket probably doesn’t need glass, it would be a good learning experience. Before you know it you’ll be glassing everything (not limited to rockets).:)


I checked the previous thread.

You are building a rocket similar to the PML IO (your suggestions) or Callisto (RockSim's suggestion). My guess is that the ACME fincan makes the rocket tail heavy and therefore the long tube length recommended by Rocksim may be necessary for stability.

1.) PML says you need to glass if you are planning to use Mid-I or higher motors on a rocket of this size. Go to the PML website for their recommedations and follow them.

2.) Your descent speed on the main should be 15 FPS. A 36" chute is too small. This rocket will go up over a mile with a mid-I motor and probably should be dual deployment.

Bob Krech
My intention is to use it with 29mm's to start with so it won't get anywhere near that high until later.
I still have to 12" section that I cut off and will save it for the start point if I decide to go with dual deploy at a later date.
I really don't have any real idea what weights will be, I'm going purely off of what RockSim tells me.
You are most certainly correct on the chute size, it just seems BIG to me; I do have a grain silo availabe for free-fall tests from something less than "run a long ways after it" altitudes before I launch it so I can see what should work.
Thanks for your ideas and help,
I gotta go to bed soon,
Everybody have a good one,
I agree with Bob on this. I usually shoot for a maximum decent rate of 15 ft./sec. and sometime go closer to 10 ft./sec.; I’d rather walk than repair. Once you go with dual deployment the larger chutes aren’t as much of an issue.