Follow-up question re fiberglassing QT tubes

[Murrill]

First of all, a big "thank you" to everyone who responded to my earlier post re fiberglassing. It's so nice to post questions and get so many helpful responses.

As a result of the feedback I received, I believe I'm going with the PML Patriot (1/4) for my Level 1 attempt in January. Also as a result of the feedback I received, I do not think I will glass the tube. (I'll admit it, I'm intimidated by the thought.) So I'm going to order the kit with the standard PML Quantum Tube. However, I would still like to glass some internal fin fillets, and maybe even the external fin can area as well. Both from reading the PML web site and the replies I received to my earlier post, I know that the QT is not recommended for glassing. My question is, if I rough these areas up pretty good with sandpaper, will this limited glassing hold up on the QT? I'm using West Epoxy system (105 / 206). Also, if my construction techniques are up to snuff, and if I'm successful on my Level 1 attempt, do you think this rocket will be able to handle some 38mm "J's"?

Again, thanks so much for all the responses, it's been a big help.
John Murrill

 

[swimmer]

Murrill,

(My opinion only)

Want a good strong fin can? Do your internal fillets then foam fill your fin can. In fact, I've read you don't even need internal fillets when you foam fill.

I do apply internal fillets and I do foam fill on my larger rockets. The fin can becomes one complete assembly when the foam is used. I just don't know how much more durable one could make the fin can. The weight penalty is minimal.

Or, no foam. Make good internal fillets and you should not have any problems. Glassing may be a little overkill.

Don't forget the pictures.....

 

[KermieD]

I'm a big fan of the foam as well. Make sure you use 2 part foam, though, not the stuff in a can you can get at Wal-Mart. The single part stuff can expand with temperature increases after you think it's set and this causes problems.

On the outside, you're correct. If you want to glass, you're going to have to rough up the QT pretty good. You'll probably want to use a 60 grit sandpaper or so to get it good and rough. I'd also recommend using the 3M Metal sandpaper as opposed to the regular stuff for woodworking. I never thought there was a difference until I borrowed some from Carl to get an epoxy bubble shaved off the inside of a MMT. It's a HUGE difference.

All told, though, I don't think glassing is necessary for what you describe.