Fiberglassing Advice Needed

You don't NEED to let it sit a day or two between wraps. It is ok to put the second layer (some places claim better to) while the first layer is in the "leather" stage.

I don't even slot my tubes until I finish glassing. If you do, an exacto knife is enough to cut through it (fiberglass, particularly in the leather stage) isn't that strong.

I'm just gett> Okay, so I'm going to take that big step from model rocketry into HPR

1 wrap of 4oz will hardly make a difference ,Try at least 6 or 7 oz cloth; Or use 3 or 4 wrap of 4oz cloth; if you want to use heat shrink tape , you will have to use couplers or something to keep the tube from crushing under the stresses when you heat up the shrink tape .

JD

For my 1st L1 H powered rocket attempt, I was thinking of just sanding off the glassine outer wrapper on the BT, and then applying an epoxy finishing resin externally to allow it to soak into the paper BT and harden it up....will this suffice for a H powered model?

shockie B)

Be careful about the heat shrink tape over a fin slot. I've done that once... once... The shrink tape pulls the slots together giving your tube a hour glass shape where he slots are. What you need to do is put blue tape on the inside of the tube over the fin slots to keep glue from getting inside the tube. The slide a coupler at least the same length as the slots into the tube to keep it from pinching together too much. I've even thought of filling the fin slots with putty after I have done the above. This will keep them from filling with glue. The putty will chip out a lot easier than epoxy. Saving you time.

Geoff

You expect advice from any of us "evil" HPR guys? Surely you jest.

;-)

Anyway, the paper alone will suffice for H motors. I would think the process you describe would only add needless weight without adding much in the way of strength.

No need to glass unless you want the rocket to hold up better to stresses incurred during recovery and transportation, as that is when they usually get tweaked.

Not needed.

Joel. phx

Aerocon is a good source for the shrink tape, as well as alot of other goodies

see

the epoxy curing gives off enough heat to make the tape shrink

IMO, you don't want to wait so long between layers. If the epoxy is fully cured, you will have a mechanical bond (requiring some roughing up of the underlying layer), but not a chemical one

though I don't see why you can't do all the layers at once

- iz

Matt wrote:

I have the 1st and 3rd video tapes from ShadowAero, and I heartily recommend them. The first covers shrink-wrapping tubes, and the 3rd covers fin and nose cone molding. They cover all the details you need to get started.

- iz

JDcluster wrote:

under the stresses when you heat up the shrink tape .

very good point!

- iz

Geoff Huber wrote:

Don't waste your time sanding, instead taker a sharp hobby knife & find the seem of the outer most wrap ( glassine )meets the end of the tube; take the hobby knife & carfefuly cut along the seem line NOT TOO deep that it cuts all the way through just the top layer for about 2-3 inches or less; next use the HK to lift up the outer layer ( the shiny layer ) once you get a hold of it peel it slowly untill it's unwrapped the entire tube...

Now you are ready to "Glass" your rocket.

JD

TRA: 4486 L3

I'm probably going to repeat what's already been covered, but here goes... :-)

Use two layers of 4oz glass for reinforcement layers, and the 2oz (or lighter) as a 'finish' layer. Stronger that way. Depending on what you mean by 'two layers at once' the answer is yes and no. I use a technique that involves applying the epoxy to the fiberglass, sandwiching it between layers of plastic, and squeegeeing out the excess epoxy. It makes for a good cloth/resin ratio, but it doesn't lend itself too well to cutting two pieces at once. I've found, however, that you can apply the first layer... and by the time you've got the second layer wetted and cut, the first layer has cured enough to give a decent bond

If you're intent on using shrink-tape, then you've GOT to reinforce the tube with removable couplers... or it'll crush under the pressure. When I `glass tubes that have pre-cut slots, I wrap the couplers with waxed paper - waxed side facing out - and wrap enough layers of masking tape to form a 'dam' at the edge of the tube, so that no epoxy can leak in that way. You'll have *some* sanding to do, as there's no way to TOTALLY prevent epoxy from getting under the slots, but it'll be minimal.

Have a look at John Cokers' website (sorry, no URL handy...) for a couple of excellent writeups on fiberglassing techniques.

Do two layers at once; just make sure you get the cloth tight as you go.

Provided you don't deform the tube, that works well. Although why not just wait to cut the fin slots until after the fiberglassing?

A cheap and easy form of shrink tape is sold as "basket wrap" at craft stores. Just be sure to put a thin layer of wax (I use floor wax) on it, or it'll stick to the epoxy. Hit it with a hairdryer after wrapping, and it shrinks down nicely.

-Kevin

IMHO, you're better off with 2 (or 3) layers of 1/2X (or 1/3X) cloth than a single layer of X cloth. FOr this rocket, rather than 1 layer of 4oz and 1 of 2oz, I'd jsut do a triple wrap of the 2oz stuff. Do the middle layer at a

45 degree bias to the other two layers for maximum strength, and of course stagger the seams so yuou don't end up with one high spot.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Change your mind? ;-)

Why is that? And no, I ain't trolling you either. Just curious.

Well for one the weave doesn't line up so you get more threads per area. The

45 degree thing ads strength in a different direction than the others.

I've been do> >> >> > Okay, so I'm going to take that big step from model rocketry into HPR

very good points ...

in this approach, do you wrap the layers after a setting period for each, or immediately after each is wrapped

and will you please say more about how to handle the seams for each layer orientation?

- iz

Bob Kaplow wrote:

Alex Mericas wrote: ... > Also, I had a rough landing on asphalt

this delamination happened because the adhesive did not stick to the tube. what kind of surface did the cardboard tube have? did you rough up the tube, with say 150 grit sandpaper before glassing?

you can repair these little squishy spots by drilling two little holes and injecting some more adhesive. be sure to get all the air out of the 2nd hole. close up the holes with masking tape so it won't drain out while it is setting up.

(I wrote adhesive above because I don't know if you are using epoxy or polyester or whatever.)