What to use when assembling fiberglass rocket kits?

I am just getting into HPR. I just build a rocket for my L1 attempt which I am hoping to do in a couple weeks. In the mean time I bought a tiny fiberglass kit (about 20" tall in total) at a launch down at Brother's Launch site in Oregon. Even though this is a little kit I am going all out (fiberglass, rail launch, aluminum retention ring, etc).

I have been teaching myself everything from day one, with the A engines and 7" parachutes, because none of my family or friends do this type of stuff, except for my girl friend who is learning along with me. I just found one person at my workplace who does rockets, but he does Os and Ps. To him anything under a K is trivial and because of that he is not too much help for getting me started :/

For card board rocket kits I've always used super glue, either 1-3 second, or 3-5 second depending on the purpose. I was thinking for the fiberglass kit that something such as J-B weld, or marine epoxy would be more appropriate. On the product page for the engine retainer they recommend J-B weld, but should I use that to secure the bulk heads, engine mount, and fins as well?

I know that marine epoxy is made for fiberglass so would something such as Locktite's marine epoxy work well for the fins and engine mount?

Those are just my thoughts, and I am very open to any other suggestions.

Thanks, guys!

I'd just get the 5-minute stuff in 2 bottles (not the syringe) from your local home depot/lowes/hardware store. That should be more than enough for what you are doing. You probably ought to use JB weld for the metal retainer though as it is a bit more heat-resistant than regular epoxy.

Honestly, you could build the whole thing using JB weld if you wanted. Search for "double dip" and you can see crazy jim's way of attaching fins. Quite strong and no need to worry really.

DO NOT USE SUPER GLUE on fiberglass. It just won't hold. Superglue is good for tacking on but one sharp hit and it shears right off.

Whatever you do. Wear a mask when you sand and gloves when you use epoxy! Good luck!

All epoxies work well, including the 5 minute and 20 minute fast-cure variants. I myself prefer West Systems epoxy, as I work part-time doing marine work, so I have quite a bit of it already. Generally, most mid-power fiberglass kits can be built strongly with super glue and five minute epoxy. But, it is good practice to use the better grades of epoxy (West Systems, Aeropoxy, US Composites, etc...) on the smaller fiberglass kits.

Look up West Systems Epoxy, Aeropoxy Structural, or Rocketpoxy (on Wildman Rocketry).
They are sold in Pint and Quart sizes. (Some other sizes too, but those are all I remember.)

Superglue is very brittle. It is good for tacking, but not for the bonding.

You can use the little Loctite tubes, but you will go through them FAST.
Make sure that you sand anything to be epoxied with 60 grit sandpaper to improve adhesion.



What kit did you get?

Also be sure to post a few pics of the build, we LOVE that sort of stuff!

Welcome to the forum!

Matt

Thanks for the replies everyone. I figured that super glue would not hold up. What is the advantage to using the two bottles rather than the dual tube syringe? The marine syringe is almost 1/3 the price of the two bottles. I just don't think I'll be using it enough and I bet the 8oz bottles will harden up on me long before I would go through the whole thing.

I might just buy JB weld since I need it for the engine retainer anyway - and I've already worked with it on other, non rocket, projects.

I took a look at the linked forum, that seems like a pretty easy way to go about it. I do want to make sure that the fins are on the rocket pretty securely. I have a little F59 I hope to do the first launch with, but I am planning on moving up to an H in this little thing and I don't want it to fall apart when it's accelerating that much.

The kit I picked up wasn't labeled, but I can post a photo of the parts when I get home tonight... I purchased it from Bay Area Rocketry's trailer at the launch. Looking at their website I think that the kit might be MadCow kit, but I can't be for sure since there aren't any photos on the product pages. It looks like it will be super fun to fly. I'm gonna hold off on the build until my girl friend gets back in town on Wednesday but I will take some photos so I can post them.

blackbrandt said:

What kit did you get?

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I think I got a slightly modified MadCow Piranha. The kit I got seems to be nearly identical but the fins are different shape, and there is no recovery included.

I use this



Proper prep is more important than what glue you use

this would also be a good choice

https://solutions.3m.com/wps/portal...ECIE20SOG5000000_nid=1P1T733F35be1K3HXBTMF8gl

Epoxy wont go bad before you use it. I've got quart sets that've been on my bench for over a year now. Still rocking it. As long as you keep it sealed you're fine. The little syringes are ok, but a few things to remember. At those volumes you're lighting money on fire for lower quality epoxy. It's hard to store excess in the syringes. and for some things, 5 minute set times are too fast. However if you're in a bind and can't put out for a quart kit, they should be fine. I imagine West Systems would be easy enough to find in Portland though (try marinas). JB weld isn't terrible, but it's heavy and goes the other direction and takes forever to set.

The rocket is more likely to come apart from a bad deployment or hard landing than under thrust.

blackbrandt said:

Look up West Systems Epoxy, Aeropoxy Structural, or Rocketpoxy (on Wildman Rocketry).
They are sold in Pint and Quart sizes. (Some other sizes too, but those are all I remember.)

Superglue is very brittle. It is good for tacking, but not for the bonding.

You can use the little Loctite tubes, but you will go through them FAST.
Make sure that you sand anything to be epoxied with 60 grit sandpaper to improve adhesion.



What kit did you get?

Also be sure to post a few pics of the build, we LOVE that sort of stuff!

Welcome to the forum!

Matt

Click to expand...

I can't agree more, on all counts, how nice of you,
First,
Welcome to the forum and the hobby.

Try Aeropoxy Structural or Wildmans Rocketpoxy.
The price will deter you at first, but it doesn't go bad,
and you'll go through it faster then you think.
The 60 grit sanding on fiberglass is critical, don't skip or forget it.
I always used JB weld on motor tubes because it tolerates heat better,
I'm at the point, I don't think the outside of the motor tube gets hot enough to warrant it.

The guy at work that shunned your interest in rocketry because you were
not at an advanced enough level to be worth his time,
Absolute shame on him.
You're not missing anything all of the people here on this forum won't gladly give.
I feel honored when a young person or a lesser experienced person asks my advice.
No one is born knowing everything, we all learn as we go.

Teddy

Yea, I forgot to comment on that part. If the guy claims to be blowing off O's and P's and isn't being helpful, I'm wondering if he actually does. Everyone, and I mean every single person I've met who's into rocketry simply can not shut up about it. It's as if they give awards for hooking other people into the hobby.

[stands on soap box] Maximum bond strength is obtained with 120-240 grit. I see some really bad ideas floating around here. Scoring with a saw blade is one of them. You only want to abrade deep enough to expose the top of the fibers not cut them. You bond is molecular not mechanical. You need to activate the surface so you need to bond within 8 hours of surface prep. [/soapbox]


Your bond prep should look like this

MEK /Acetone or Propanal wipe untill your lint free clean cloth comes off clean.
Abrade with 120-240 grit paper until a dull finish (water break) is present. You shouldn't see any shine.
Wipe with MEK ect again until a clean rag is present bond immediately.


This may be slight over kill for a hobby rocket but this is how to obtain maximum bond strength.

onebadhawk said:

Welcome to the forum and the hobby.

Click to expand...

Thank you.

onebadhawk said:

The guy at work that shunned your interest in rocketry because you were
not at an advanced enough level to be worth his time,
Absolute shame on him.
You're not missing anything all of the people here on this forum won't gladly give.
I feel honored when a young person or a lesser experienced person asks my advice.
No one is born knowing everything, we all learn as we go.

Click to expand...

He is a very nice man, and it's not that he shunned me - he actually picked me up some parts when I asked him too, but I think that the things I am doing are so trivial he doesn't really understand. He is a man in his late 40s who builds rockets with 50,000Ns of thrust and I am an 18 year old intern who hasn't even touched anything larger than an H.

On those same lines, I'm only 18, and I don't want to spend $40 on epoxy for a rocket that cost $110. I think I'll just stick with a $5 tube this time, and maybe when I build an L2 rocket I can put in the cash to buy larger quantities of epoxy.

DizWolf said:

Yea, I forgot to comment on that part. If the guy claims to be blowing off O's and P's and isn't being helpful, I'm wondering if he actually does. Everyone, and I mean every single person I've met who's into rocketry simply can not shut up about it. It's as if they give awards for hooking other people into the hobby.

Click to expand...

Haaaaaaaaaaaa
oh man is this trueeeeeeeeeeeee
Oh boy did I just get a good laugh on that one.
Tanxxxxxxxxxxxxxxxx

Teddy

DizWolf said:

Yea, I forgot to comment on that part. If the guy claims to be blowing off O's and P's and isn't being helpful, I'm wondering if he actually does. Everyone, and I mean every single person I've met who's into rocketry simply can not shut up about it. It's as if they give awards for hooking other people into the hobby.

Click to expand...

Yeah, he really is. He has a crashed P motor case in his cube as well as the nose cone of a rocket called "Beer Daddy" that he made the motor for. He really is legit. He is the one that talks during part 2.

The video really is worth watching.

yes shame on that guy for not helping you. but also don't be afraid to ask someone else for help theres lots of people that will be more than willing to help :wink:

kjmccarx said:

On those same lines, I'm only 18, and I don't want to spend $40 on epoxy for a rocket that cost $110. I think I'll just stick with a $5 tube this time, and maybe when I build an L2 rocket I can put in the cash to buy larger quantities of epoxy.

Click to expand...

Ok, I know what you are thinking here. But here's the rub, you will repeat WILL do it eventually. Better epoxy doesn't go anywhere until you use it and the better stuff is so much easier to work with. I have been using the same quart of epoxy for the last three years. I personally like marine grade stuff, I use MAS epoxy because it's a 2/1 mix. It's easy to measure out by weight and that easy translates to repeatability. In my old RC days, I can't tell you how many projects I messed up because of poorly measured epoxy that didn't ever fully cure. I despise BSI epoxy to this day.

That being said if I were starting out now and I wanted the best I could get for the bucks, I'd spend the $15 or so for the tube of Loctite Hysol along with the $22 applicator gun and be done with it. It's great crap for gluing. The only down side is it's not a laminating epoxy if you decide you want to work with glass layups and laminating.

https://www.mcmaster.com/#loctite-hysol/=nfs8yi

I have done all my builds to date using hobby shop epoxy (Bob Smith type) comes in a pair of 4oz bottles for about $10. I get mine from Hobby Lobby, with the 40% off coupon. The issue with the syringes is that they are expensive when you break it down to dollars/oz. If syringes work for you, then by all means do it that way. The great thing about this hobby is as long as it's legal & safe, do it the way that works best for you.

I like the Devcon 30min epoxy https://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXC026&P=ML. It has a 3 year shelf life. Use the JB Weld for heat sensitive areas like motor retainers.

Most important - rough up the surface of the fiberglass with some 80 or 100 grit paper.