Windscreen fiberglassing tips

01 Oct 2003 Windscreen fiberglassing tips

dkerns91 wrote:
Fellows,
I am getting ready to start my windscreen fiberglassing. I feel a little intimidated but I know I can do it. I am ordering my materials from Wicks. I went to a boat shop and he was much higher. I plan on using the 9.6 oz pieces of cloth. Should I use smaller pieces? Some have told me to use Superfil but Vans recommends Microballoon. My videos show me how to mix it up. I think I can do
it but if anybody wants to give me some advice or insight before I get started I sure would appreciate it.
Thanks in advance,
Darren Kerns
RV 591RV (reserved) From: Rob Miller
Subject: Re: Windscreen Fiberglassing Questions

Hi Darren

I suppose one could write a book on this subject, but I’ll keep it brief. I have a flying -8 and before this my experience was in RC models.

1. After you’ve sanded the gloss off the windscreen and the aluminum skin, I like to use light .75 oz cloth from a hobby shop and add one layer of this.

2. Next, use Superfill or microballons to make a nice little fillet so the transition is smooth.

3. Using a series of 2″ (each about 6 inches long) strips of 9 oz cloth, apply to the base of the windscreen. Let dry or apply another layer on top if you fell brave.

4. Make about 4 layers total with the seems of these one inch stipes in a different spot each time. The first course is 2″ wide, make the second an 1/8″ narrower at 1 7/8″. The third at 1 3/4 and so forth. This will build in a taper and eliminate a great deal of sanding.

5. Add peel-ply dacron in the final coat to soak up extra resin and make the surface smoother.

6. When dry, countersink a series of pop rivets into the top of you glass and into your aluminum skin. This adds an important mechanical bond (you don’t want the windscreen to come off).

7. Add filler and sand for 4.5 years and you’re done! 😉

8. Note: Do the canopy bow at the same time and make sure you rivet down the lower 4 inches of each side of the bow fiberglass. (It’s very easy to kick with your foot and break loose climbing in and out–don’t ask how I know :(.

I hope this helps

Rob Miller N262RM “Bad Cat” 150 hours
Visit us at www.badcataviation.com

From: “RV8List”
Subject: Re: Windscreen Fiberglassing Questions

I did this recently and found the following to work well.

Superfill: I would highly NOT recommend this product. For filler, use the West System. They make excellent fillers. The 410 is an extremely quick sanding filler that is just for fairing. The 407 is decent for compression loads but a bit tougher to sand. If you really need something strong, I just used fiber flour…you can buy this from any fiber glass shop.

9.6oz is fine, although I like 6oz for doing build ups. If you haven’t purchased your epoxy, I would recommend West System. It is more expensive, but worth it. Also get the metering pumps for them (only $10 or so). Get a gallon of the resin because you will need about 3 quarts of it. The metering pumps are nice because, you will be wanting to mix small amounts of epoxy often. Use the fastest curing hardener you can get as your lay-ups aren’t large and you don’t want to be waiting for days for the stuff to get hard (I think this is West System 205). Another nice thing about the West System is the amine (I think this is what it is called) that floats to the top is minimal which makes the sanding go much better.

Follow the directions in the manual for making the lay-ups as they work well. I did mine in one evening. It took another evening to sand into rough shape using a 3″ dia PVC tube with sandpaper wrapped around it as a form tool. The stuff over the top I just used a soft block to form. I also used something like 40 grit to get the thing into the basic form. Go slow around the edges of course when sanding. When you get it basically to the right shape, fill the large depressions with 410 filler mixed in with the epoxy. Be aggressive with the sanding grit for now. Then to get the big scratches and small voids out start using a CATALYZED high build primer. Prime the hell out of it. Even to the point of sagging and running. Use your finger to force the primer into any voids as you don’t want to span voids, but fill them. Then spray guide coat (available at any automotive paint store). Wet sand until the guide coat is gone and repeat as necessary. These last two steps will save you tons of time and get you a really nice finish.

Save yourself some money and buy a 100 pack of 3M 500 grit sand paper. I also bought a 100 pack of 3M 120 grit. You will use the 120 to get things close to the final form. The 500 to sand primer with. When the paper loads up (especially the 120), throw it out and get a new piece. I used all 100 sheets of 500 grit and about 75 sheets of the 120. I found that 3M really does make better sand paper and West System really does make better epoxy. I really didn’t use very high quantities of any other sand paper grits.

Too see what this method will get you, see www.rvwoody.com and click on the N232TB My Project link.

Todd.

From: “Rick Jory”
Subject: Re: Windscreen Fiberglassing Questions

I used the West Epoxy System, which is great . . . and did the filler using microballoons. I tried Superfil, but didn’t like it at all. The nice thing about mixing up your own microballoon “slurry”, you can control how thick you make it. Also, for some reason I would get air bubbles in the Superfil (noticeable when you begin to sand).
As to the process, somewhere I read how Van’s did his factory 8A . . . I made a paper pattern of “half” the windscreen to top skin interface (of course, since it is symmetrical, if you flip the pattern over you have the other half, i.e. one side will work for the left side of the plane, the other for the right side). The pattern gives you the “curve” you need for cutting the fiberglass cloth strips. I put two layers of black electrical tape on the Plexiglas representing the top “edge” of the fiberglass/filler. Now, as to cutting the fabric . . . I started with a very narrow section, perhaps 1/2″ in width . . . and made strips going up in size (width) by 1/4″ or 1/2″ or so. The narrowest strip presses into the junction between the plexi and the top skin . . . then as you add the wider strips you end up with a nice smooth transition. Of course, you do not cover the black electrical tape . . . your strip just goes up close to it and a very, very thin layer of filler actually touches the tape. When you remove the tape you won’t have a “thick” fairing section, you’ll have a nice transition from the plexi into the fairing. Where the fairing goes into the top skin, you’ll need filler and sanding, but when you are done there is not “seam” here either, just a nice, smooth transition.
The roll bar is fairly simple. I covered the rear canopy with clear transparency (acetate), closed the canopy shut, and just started building up a layer of fiberglass similar to the windscreen-to-topskin (i.e. making a paper pattern, etc.). All in all, it ended up being fun. Good luck.
Rick Jory RV8A (N184RJ)

From: “Ed Perry”
Subject: Re: Windscreen Fiberglassing Questions

Hi Darren,

I used 5 strips of carbon fiber for the roll bar portion and about 4-6 layers of fiberglass for the part that seals the windscreen to the fuselage. I made mine a separate piece. The reason was that I wanted to be able to take it off and sand it and not have to worry about scratching the Plexiglas. It also makes it handy for maintenance. I’ll tell you more if you are interested but to answer your question.
Make sure that you cut the strips that you will need ahead of time. I cut the windscreen base into 7-8″ strips and layered them over each other. This gave me the ability to make the curve around the windscreen without binding the fiberglass. That reminds me…I used modeling clay to form the arc from the Plexiglas to the fuselage. It worked very nicely. If you do this than you don’t have to fill that gap with fiberglass and resin. I have pictures of the whole process if you want them send me your email address.

Good Luck,
Ed Perry
RV-8 180/CS
70hrs.

From: “Brian Denk”
Subject: Re: Windscreen Fiberglassing Questions

It’s really not that bad, so don’t sweat it. I would not use Superfil, as there have been some instances of it cracking over time. I now have cracks in my paint around my windshield fairing as a result. Micro slurry is a great filler, and totally compliant/compatible with the underlying glass/resin layup.

I used strips of 9oz. glass tape, and laminated onto the plexi/aluminum junction in layers. You don’t have to do it all at once! Work a few layers, with small batches of West Systems epoxy, and build it up. Mask off the plexi very well with electrical tape around the base where you want a clean separation line from the plexi to the fairing. Use plastic sheet to cover the rest of the plexi. Scuff the aluminum and plexi with emery paper to provide a good bonding surface to the resin. I sandwiched in carbon fiber cloth for strength and HIGHLY recommend it, especially over the top of the rollbar. You will be placing your hand up there and putting some weight on it so you want it to be strong. The carbon makes the fairing tough as nails.

Once the layers have been built up to your desired thickness and contours, finish with a tighter weave cloth, like deck cloth often used for RC airplane wing skin laminations. This provides a tighter, smoother surface that requires less slurry filler. Squeegee on the micro slurry to fill the weave then begin sanding. A trick I learned from an autobody repair guy is when you’re feeling the surface for voids, depressions and general fubars, close your eyes and use your NON sanding hand, which will likely be more sensitive to the touch. You’d be surprised what you’ll feel on a surface that your eyes tell your brain is perfectly smooth!

This whole process is assuming you’re gluing the fairing in place as a permanent fixture on the airplane. If you want to remove it, either for
finishing then to glue it on permanently, OR as a screwed on assembly, you need to use a release agent. Autobody paste wax works great for this.
Also, resin won’t readily adhere to duct tape. The glass airplane guys swear by it for molding various funky shapes, a piece at a time.

Press on. You’ll do fine.

Brian Denk
RV8 N94BD
down for the annual from hell.

From: “Dave Hamilton”
Subject: RE: Windscreen Fiberglassing Questions

Darren,

I used fiberglass tape in various widths. It’s available from Spruce. It doesn’t unravel like cloth, is much easier to use and yields great results.

Sometime in the past two years or so, there was an article in the RVator on how to get a great windshield fairing. I followed those directions exactly and couldn’t be more pleased with the results. I have a buddy (Dane Patterson) who did his the same way with the same great results. He even mixed in some black fiberglass pigment (also
available from Spruce) so when you sit in his airplane and look out the windshield you see black instead of seeing the raw fiberglass thru the wind screen. He painted the top of the glareshield flat black BEFORE installing the windshield. The results were very professional.

Dave Hamilton
N880RV
#80001