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Well-Known Member
Jan 25, 2009
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Hi all,

I had a thought - some of you have yet to experience what expanding foam can do for you MPR and HPR rockets. I'd like to let you experience it. What I will do is make up a small sample of the foam and let it fully expand, then send it to you to see how totally awesome it really is! I will likely have to charge a small shipping fee (less than $2) to get it to you, but I think that once you experience it and see what it can do for your rockets, you'll be more than glad to go out and buy some for yourself.

Please PM me if you are interested!

Well, you might want to include a very small chunk of cured glue AND a small sample (maybe 5cc) of the uncured stuff, so you can pour some in a BT-5 or something and watch the magic.
I considered that - but I'm not sure how I would keep it separated before the recipent gets the chance to activate the cure...any ideas?

dannon yogurt cups with glued on lids, then have the interested customer cut a hole in the top.
Find your local photo lab and they will be more than happy to give you LOTS of the little cannisters that film comes in... I have bags of the silly things coming out of my ears...

Of course they might think that you are using them to store your....um...oregano... DON'T DO DRUGS!
Most hobby shops that sell RC planes and boats will have two part foam. It'll probably be NHP brand, and is usually located in the same area as epoxies and glues. If you have a local shop near, you might want to check it out. That's how I came across some.
How much expansion can one expect....say in a paper shroud boat tail or an paper nose cone add-on?

Look at is this way. I use an approx. 1/8" thick layer of each part - so I then have a 1/4" thick layer. That's about 5mL in my measuring cups. I throughly (sp?) stir it all together with a popsicle stick (no toothpicks here!) and in about 5 minutes, the foam is completely expanded to about 2.5" tall. About a 10x expansion. The good thing about this stuff though is that it is very easy to carve down with your hobby knife and simple to take the Dremel tool to.

So, if you're going to be using this stuff in a tailcone, I would use it before it is installed. If you're talking about the TLP Hawk kits, you've got two options.

1. Glue the motor mount in according to the instructions, then punch 2-3 holes in the sides. Pour the foam in the hole, then let it expand outwards through the holes. It might take more than one application though. This is probably the messiest option.

2. Take the CR that goes at the tip of the boat tail (the wide end) and punch several 1/4" or more holes in it. Then BEFORE you glue all the other CR's in, and so you have a good place to work, pour the foam in through those holes and let it expand. You may run into a bit of bulging on the sides, but just squeeze that down with your hands, I would think. Let it expand throughout the tail cone and then trim what expanded through the holes in the CR off with your hobby knife. MAKE SURE that you have a spent motor casing in the MMT during this procedure - the foam is liable to squish it!

what does it weigh?

do the benefits of putting a heavy mass at the rear-end of a rocket exceed the benefits of building a light model?

just curious.
It's very, very light. I tried lighting a sample on fire, and it just blackened, and whatever flames were on it went out momentarily.