Can I make a PML phenolic tube more durable without fully glassing?

Have had this AMRAAM 2 kit for a while, before the Quantum tubing I guess (been out of rocketry for ~10 years). Is there anything I can do to help prevent the shattering I read about? I am very allergic to FG (not the epoxy) so really don't like to use it much. But am willing to use a bit of it if it will help. I was thinking of maybe a few circumferential bands of FG in strategic (??) places.

What would help is if I knew how these tubes get their reputation, like how the failure mode starts. I really don't expect it to crumple like cardboard, or to survive non-deployment etc. I really like the look of this tube, and the whole kit for that matter (first class!)...I suppose PML might sell me a AMRAAM 2 Quantum tube if everybody says don't even bother with the phenolic one? Thanks.

CraigF said:

Is there anything I can do to help prevent the shattering I read about? I am very allergic to FG (not the epoxy) so really don't like to use it much.

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I forget who makes them, but there are a couple vendors with non-fiberglass sleeves (Nylon or Polyester?) that are built much like the fiberglass/carbon fiber sleeves, and used in a similar manner (slip over tube, stretch a bit, tie off, and impregnate with resin of choice). I've also read somewhere about using pantyhose instead of fiberglass sleeves to save dollars... I'd lean towards using one of the commercial non-fiberglass sleeves, but then again it's not my money .

Just a thought!

-Rick

Thanks. I forgot to say that weight will be a significant issue I think, in that I'm pretty limited by the motors I can get.

I would like to find out how the phenolic breaks. Then maybe I can think of something. I have a little rocket (Mach Buster) that I think is phenolic and it was never a problem (least for breaking...).

If the phenolic cracks starting at the tube ends/cuts, then some thinnish FG bands at the tube ends and fore/aft the fins might help prevent that?? If the tube shatters after freefalling a hundred feet, I can live with that....

The biggest problem with the brittle phenolic is localized g-forces. If the tube drops and lands flat, I doubt any damage would be done. If it lands on an edge of the tube, the edge will chip and might shatter. If it were to land mid-tube on a sharp edge, more than likely the entire tube would shatter.

I think your highest rate of failure will be the edge and not the mid-tube failure. Some light-weight fabric (carbon, fiberglass, kevlar? nylon, poly, etc) over edge should add enough strength to counter the brittleness of the phenolic.

Another option is to replace the brittle phenolic with like sizes of flexable phenolic that can be found from many resellers. I've had very good luck with the flexable phenolic from RedArrow (and they'll ship to Canada customers as well!!)

-Aaron

Thanks, sounds like you have the same impression as me. The supplied phenolic tube is so nicely made and cutout...I hate to not use it! Believe me, I know that any tube I made all the fin cutouts in would probably fly like a screw.

My past experience ordering longish tubes is the shipping/etc. cost makes it pretty expensive, largely due to the length (though I suppose I could get short lengths/coupler, but may be a pain for fit with the piston thingy). So I'm trying to get by. If the tube fails (I should probably say when), I suspect many of the goodies will be salvageable anyway.

I always reinforced my LOC etc. cardboard tubes around the edges to prevent rips. Seems to work. Was hoping something similar might help with the phenolic. As you can tell, I am being kinda stubborn about using it, just trying to find the "best" MPR way...

Like most phenolic tubing it's brittle and does crack.

try double walling it with coupler tubes, makes it very strong and I have no problems after doing that

also CA or thin epoxy to beef up the ends

no FG allergic reactions involved

never like Quantum tubing, Ive had it shatter on me on my Bullpup, so now it's dual walled BSD tubing.

Build it stock,
and fly 'til it breaks...

...then you have the perfect excuse
to buy and build yet another one....

I've wrapped 3" phenolic in two wraps of 6oz E-glass. it's still brittle, and chips easily, shatters if you really whack it. so, Dr Sue's right on the money, don't bother with the glass, just build it and blast it and make another.