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How much fiberglass needed?

R

rightrudder

Well Known Member
Hi guys,

I'm placing my weekly ACS order, and it's time to get some fiberglass cloth. Previous threads have indicated that the ACS part # 7781 cloth works well, so that sounds good to me. How many yards will I need to do both the windscreen surround and the rear skirts? It's 50" wide. Thanks!!
 
A couple yards for w/shield bare minimum, if it's a 8 slider maybe a yard or 4 depending on your luck & skills. You will find having a few yards extra will come in so handy later on for other odd jobs.
 
rightrudder said:
Hi guys,

I'm placing my weekly ACS order, and it's time to get some fiberglass cloth. Previous threads have indicated that the ACS part # 7781 cloth works well, so that sounds good to me. How many yards will I need to do both the windscreen surround and the rear skirts? It's 50" wide. Thanks!!
Click to expand...

7781 is an 8-harness satin weave (7 over, 1 under), marvelous for highly compound curvature because the threads can slip and slide over each other to adjust. However, that means it is also a tight weave, so it's a little harder to wet out without trapped air bubbles.

I always have 7781 in the shop, but you might like a plain weave (1 over, 1 under) for the not-so-curved canopy and windshield fairings...maybe 3733 (medium) or 7500 (heavy, again a shop standard).
 
Thanks a ton for the replies, guys...great info. Four yards it is, then, as it's not that expensive and it's good to have extra.

Great specifics on the various weaves, Dan. I'll check those out. If I were to use 3733, roughly how many layers would it require for the windscreen surround? Do the rear skirts (slider) need to be thicker/more layers?
 
rightrudder said:
If I were to use 3733, roughly how many layers would it require for the windscreen surround? Do the rear skirts (slider) need to be thicker/more layers?
Click to expand...

Doug, read this...

http://home.hiwaay.net/~sbuc/journal/smart.html

Twice.

Here at VAF we embrace the axiom "There are no dumb questions" because the goal is to get everyone in the air safely. However, the question can tell us a lot.

The number one error made by builders new to fiberglass work is failure to conceptualize...to fully grasp what they want to accomplish, and then work out all the steps to get there, in advance, in detail, starting from zero. Instead they start hacking up cloth and slapping it on willy-nilly, use too much epoxy, and wind up with a lumpy mass that looks like a cross between a meteorite and a hairball. For them, the next step is a load of bondo, or some other "easy" filler...when really good composite work takes almost no filler at all.

Conceptualizing means building the imaginary part to completion, from zero. When you ask "How much glass cloth?" you're telling me that you have not conceptualized....as the first steps are to get some dimensions, and decide how may plies the layup will require to get the finished thickness necessary for the desired stiffness. The answer to your question is found in Area x number of plies. Rough thickness per ply is right there on the order page in the catalog.

How much total thickness is desired for a finished part? Evaluate its use. Is it structural, or aerodynamic, or merely cosmetic? Does it get a lot of human abuse, or does it have a gentle life? Is it screwed on, or bonded evenly? You get to make these decisions based on what you conceptualize as a result, as it's a custom built airplane. If fabric choice, number of plies, and ply orientation are critical, the information will be in the plans...as it is with real composite airplanes.

I beg your indulgence....better to teach how to fish....
 
DanH said:
Doug, read this...

http://home.hiwaay.net/~sbuc/journal/smart.html

Twice.

Here at VAF we embrace the axiom "There are no dumb questions" because the goal is to get everyone in the air safely. However, the question can tell us a lot.

The number one error made by builders new to fiberglass work is failure to conceptualize...to fully grasp what they want to accomplish, and then work out all the steps to get there, in advance, in detail, starting from zero. Instead they start hacking up cloth and slapping it on willy-nilly, use too much epoxy, and wind up with a lumpy mass that looks like a cross between a meteorite and a hairball. For them, the next step is a load of bondo, or some other "easy" filler...when really good composite work takes almost no filler at all.

Conceptualizing means building the imaginary part to completion, from zero. When you ask "How much glass cloth?" you're telling me that you have not conceptualized....as the first steps are to get some dimensions, and decide how may plies the layup will require to get the finished thickness necessary for the desired stiffness. The answer to your question is found in Area x number of plies. Rough thickness per ply is right there on the order page in the catalog.

How much total thickness is desired for a finished part? Evaluate its use. Is it structural, or aerodynamic, or merely cosmetic? Does it get a lot of human abuse, or does it have a gentle life? Is it screwed on, or bonded evenly? You get to make these decisions based on what you conceptualize as a result, as it's a custom built airplane. If fabric choice, number of plies, and ply orientation are critical, the information will be in the plans...as it is with real composite airplanes.

I beg your indulgence....better to teach how to fish....
Click to expand...
I think you're reading too much into my question. I read the link you provided, only once, because it embodies my approach as well. I do a lot of research, read build logs, look at tons of pictures, and ask a lot of questions (stupid or otherwise). The actions I perform on my RV I've rehearsed multiple times in my mind. Yeah, I'm gonna make occasional mistakes as a first-time builder, but using the resources of this board I believe I've kept them to a minimum.

Bill's link was exceedingly helpful....I watched an hour-and-a-half's worth of video from Van's on the windscreen bonding/fairing process, and now I have a really good grasp of what's involved. I like neat and tidy work, so it's not lost on me that neat layup and careful pattern-making will result in a lot less labor in the end. I'm not averse to sanding; I'm averse to excessive sanding. :):)

The more info I get here, the easier it is to conceptualize. I'm performing due diligence weeks before I cut that first strip of cloth or mix that first batch of epoxy, in hopes of nailing the result.
 
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