Fiberglassing Questions

[LMazza]

I know, I know. Probably thinking "If I had a dime for every fiberglass question". Well I have a few and I'll try to stick to those which I have not found addressed on these forums yet.

1) Does anyone have a guidline as to what weight/type of glass they use for certain BT sizes?

2) Where do you normally get your fiberglass cloth?

3) What exactly is involved with finishing a fiberglassed BT?

I'm sure I had more questions on my mind. That's what I can think of at the moment. I'll add more as I think of them. Any info is much appreciated.

 

[KermieD]

1) I choose a cloth weight based more on what I expect the rocket to go through. For my HPR birds, it's 6 oz. For stuff that isn't going to take that pounding, a layer or two of 2 oz. cloth should be fine. Opinions will differ, though.

2) I get mine from US Composites. They have great prices, quick shipping, and they have a very good laminating epoxy that's much cheaper than West Systems. Kill 2 birds with one stone that way.

3) Same thing...sanding and priming...sanding and priming...sanding and...zzzzzzz.

 

[LMazza]

Thanks a bunch KermieD. What about E vs. S glass?

 

[KermieD]

One's cheaper.

Honestly, I have no idea. I always get the cheaper stuff and haven't had a problem with it at all.

 

[Johnnie]

LMAZZA,

Wally-World (Wal_Mart) carries the Bondo brand Fiberglass cloth that comes 8 square feet to a bag, and it is 6oz. fiberglass per Bondo tech support. You can also find this glass at a local Automotive store like Pep Boys, Autozone, Advanced Auto etc.

Be warned, this glass is strong, but leaves a heavy weave pattern on your rocket that will need to be veiled with a layer of 2oz. glass. The 2oz. glass has a tighter weave, and is very smooth, which will make finishing a little friendlier.

Also for best results, it is reccomended that both the 6oz. and the 2oz. glass be put on in the same wetting, and the that way you only have to sand once... If you wait for the 6oz. to set up before you apply the 2oz. you will have to sand the 6oz. down. Besides,with the 2oz. and the 6oz. put on at the same wetting, you will have better strength with this all bonded as one...you also use less epoxy in my opinion...and don't get me started on vacuum bagging, as I would not know what I was talking about

 

[Austin]

Luke,

Application type comes in to play more than BT size when choosing the type/weight of cloth for a project.

S-Glass is less flexible than E-Glass and just a bit stronger. You see these designations when shopping at fiberglass cloth dealers like <a href="https://www.aircraftspruce.com/">Aircraft Spruce</a>, which is where I get most of my cloth. For Level 2 projects down to low power, I buy my glass cloth at the hobby store. You can get Sig cloth or other brands in 3' squares for about $5-6, which is enough for most projects. I even use it on fin glassing with L3 birds, as the cloth at the store is an extremely tight and dense weave, hence much stronger than from cloth shops. Sig 1.5-2oz cloth works fine on sport, L1 and L2 rockets, while I use the hobby shop 5-6oz Sig cloth for L3 birds. For small low to power models that I want to glass, they have ultra-light .47-.5 oz cloth that is very cool!

For bodytube glassing I use the stuff you get from the cloth shops online and the weave is a bit looser. I normally start with 5-9 oz cloth followed by a top layer of 1.5 - 2oz; the lighter cloth is so fine that it leaves less or no weave to fill with primer.

Hope this helps,

Carl

 

[LMazza]

Thanks guys! I ALMOST feel ready to dive into this now. hehehe

I hope to use this on the Public Enemy Honest John I'll be getting. It'll be good to practice on someting not so large. Wish me luck!

 

[LMazza]

Ok, I've been looking around at places to order fiberglass cloth from and I found a place with good prices and selection but I want to make sure that the cloth I am looking at is appropriate. The details are:

Industry style 7628. Boating and tooling cloth, excellent for laminations, surfacing, sealing, finishing. Epoxy and polyester compatible. Many boating, aviation and automotive uses. Great for finishing surfboards and sailboards, makes great model airplane fuselages and wings. Width of this cloth is 42 inches.

Specifications:
WEAVE: Plain
WARP: ECD 75 1/0
FILL: ECD 75 1/0
COUNT: 44 X 31
OSY: 6.0 - (Weight)
THICKNESS: 0.0068
FINISH: 643 - Developed for multilayer and bonding sheets applications but also good for general epoxy FR-4 applications. Exhibits very good wet-out characteristics.

Does this look good to you guys?

 

[KermieD]

Sounds good to me.

 

[doxiedog315]

Here is some stuff of intresthttps://www.jcrocket.com/kitchenbagging.shtml

 

[doxiedog315]

https://www.jcrocket.com/kitchenbagging.shtml

 

[doxiedog315]

sorry

 

[LMazza]

Haha, I got halfway through that article and realized I had read it before. Still good to have a memory refresher. Thanks.

I don't think I've made it to the point where I want to vaccum bag, not to mention I don't have the money for even that cheap method.

Thanks Kermie for looking that over. I'll be ordering some soon.

 

[Ryan S.]

Originally posted by LMazza
Thanks a bunch KermieD. What about E vs. S glass?

US Composites is a great place. When my dad ordered for me the lady said "are you sure you dont want S glass it is a little more expensive but its 1.5 times stronger" My dad, realizing he could get more E glass for the price of S glass, said "or I could get the E glass and put 2 layers on and it will be twice as strong" It was kinda funny the way he reasoned with the girl

 

[LMazza]

That's pretty funny. I had gone to US composites but wanting 6oz and 2oz glass and them not having the latter I decided a place with both would save me some shipping.

 

[SwingWing]

Originally posted by Ryan S.
"or I could get the E glass and put 2 layers on and it will be twice as strong"

And weigh twice as much!!

 

[daveyfire]

E-glass and S-glass differ in the chemical makeup of the glass fibers. That's about the only difference. I get my glass from US Composites (its cheap) or from Aircraft Spruce (if I need mass quantities fast). Otherwise I go to the hobby store. They have some real nice twill weave stuff for sale there!

 

[Ryan S.]

Originally posted by SwingWing
And weigh twice as much!!

true which just gives me an excuse to use a bigger motor..

 

[Nite Builder]

LMazza:
Gots to be honest, when I first started "Glassing" rockets, I was doing it in the same fashion that your doing it now, and I'm still not sure which way is stronger. By that I mean of which my style of "fiberglassing" doesn't actually use fiberglass at all, rather I use a Kevlar sock. They are available from either recoverytechnologies.com or giantleaprocketry.com and have truly made my life a lot easier. Don't get me wrong, like I mentioned, I'm still trying to find out which way"is" actually stronger and I'm quite bound and determined to do so. So, in essence, I do have to actually "fiberglass" a rocket to find this out. But I will admit, the Kevlar sock is really simplified.

After just one thin coat of 30 min.(E-glass) Epoxy, all I need to do is unroll the Kevlar sock onto the BT. The natural elasticity of the sock keeps itself uniformed better that any "vacuum bagging" I have certainly ever done and the following coats "fill" quite nicely too. About the only edge that fiberglass has over Kevlar that I can see so far is fiberglass cures a bit more rigid than the Kevlar, but not by much.

These Kevlar Socks are available in several lengths and diameters which makes matching one up to your rocket a breeze.

Just my .02

 

[LMazza]

Those Kevlar socks have interested me from the day I heard about them. What would keep me from doing that in these early learning stages I think would be the fact that one of the most common ways of finishing Kevlar is to go over it with a layer of fiberglass. How do you usually finish you kevlar socked rockets Nite Builder?

I'm really looking forward to learning how to use fiberglass although it is a scary thought. I just got the glass I ordered in the mail today so it is likely that within the next week I will be doing this. I actually can't wait!

 

[LMazza]

Well, I have just completed my first attempt at fiberglassing and it was a success!. After some initial troubles with getting the glass to lay down on the fillets I was able to get everything layed down and squeegeed. I couldn't be happier with the results.

Here is a pic of the 2oz glass still wet layed down tip to tip on the PER Hojo:

 

[DPatell]

Looks great Luke! Is that satin weave cloth? Looks good to me, what's it gonna fly on next launch??? Do I smell an L2 attempt?

 

[LMazza]

Thanks Dan. It's plain weave but it seems to be pretty tight and hopefully easy to finish.

Unfortunately L2 will probably wait until my 18th in August at least. Look for it to fly on big I's mostly however it will be built strong enough for J350's.