marchudson

marchudson

Well Known Member
About to do the forward fairing on the windscreen for my slider. I was going through the steps of the whole process in my mind. Why can't I use Flox for the entire windscreen fairing instead of layers of fiberglass? It would be much easier to shape the wet Flox into the finished fairing. What say ye?

Thanks
 
strength

I don't believe it would be nearly as strong without the fiberglass cloth.
The cloth is not as hard to do as it appears.

Mark
 
Nine layers of fiberglass cloth and and 24 hour EZ-Poxy

Nine layers of fiberglass cloth and and 24 hour EZ-Poxy covered with EZ-Poxy and micro-balloon for fill and sealed with 50% acetone thinned EZ-Poxy gave me a perfect fillet that has zero imperfections after almost 7 years of operation. I have used flox filled resin is some locations but they are so obscure that I would have to research my log book to recall where they are (maybe the tip lights). I can't say how it would hold up on the base of the windshield.

Bob Axsom
 
"nine layers of fiberglass..."

ups... i only used one layer. i think i will put some more on it.
 
The RV-10 plans show ten layers of cloth...

..beginning with 1/2" wide first, then 3/4", then 1" and so on, each successive layer getting 1/4" wider than the previous one and the last one at 3 1/2", with half of that on the windshield and half on the foredeck, for a smooth curvature, pleasing to look at:)

Best,
 
Many ways

Am no expert, but I think it depends on how you have attached your windscreen. There are many ways to skin a cat or fair a windscreen. I think it depends on if the fairing is intended to secure the windscreen or simply divert the air. Regardless I would think you want at least a couple of layers to help hold it together, flox can still fracture.

Mine is Sika'd all the way around. I then spread a layer of flox and carbon died West to make it black (did not want to see anything from the inside) in the corners and then layed 2 layers of carbon and 2 layers of glass. Then 70%flox/30% micro mix to smooth the fillet. Found the right curve by sorting thru different size plastic pipe sections and then stuck a piece of sandpaper to it and went to town. Finally a thin coat of Aeropoxy filler for the final finish. For the upper gap seal (where the slider meets the windscreen) fairing I added another layer of carbon for stiffness.
 
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Flox vs. West 410 for fillet

Any reason not to use West 410 (lightweight, sandable fairing filler) instead of flox at the plexi / skin intersection? Do these effectively accomplish the same thing?
 
Flox (flocked cotton fiber mixed into properly proportioned epoxy/hardener) is hammer tough. I'm not kidding. Mix and cure a few blobs, set them on a concrete floor, and hit them with a 16oz claw hammer. You'll become a believer.

Micro (glass microballoons) and West 410 are not flox substitutes.
 
Thanks for the response Dan. I used flox & epoxy on the snorkel, and I definitely agree, the stuff is tough as nails when cured. I guess I am wondering why you need something that tough and rigid for the initial fillet. Since the fillet gets covered with several layers of glass that provide some impact resistance and toughness, does the fillet need to be that tough?
 
Exactly

DanH said:
Flox (flocked cotton fiber mixed into properly proportioned epoxy/hardener) is hammer tough. I'm not kidding. Mix and cure a few blobs, set them on a concrete floor, and hit them with a 16oz claw hammer. You'll become a believer.

Micro (glass microballoons) and West 410 are not flox substitutes.
Click to expand...

Dan

This is exactly why I asked the question in the first place. I actually did the test that you are talking about. Mixed some Flox and made a mock up fairing between a scratch piece of aluminum and plex. The entire test piece was pure Flox, no fiberglass cloth. The Flox was extremely hard. The adhesion properties weren't what I expected but the Flox was extremely tough even up to 1/2 inch thick applications. Would the Flox have a tenancy to crack over time whereas the fiberglass might not? The fairing in my application would not be holding the windscreen in place.

Thanks for all the input.
 
Flox is strong in compression but not so much in sheer and will expand and contract differently then steel/Al/acrylic. I would not use flox by itself in this application as it just adds weight. Why not use glass? It is lighter and MUCH easier to sand. And never use flox over glass if it is the last layer before finishing.

Ryan
 
Sorry guys, missed your questions.

Noah said:
Since the fillet gets covered with several layers of glass that provide some impact resistance and toughness, does the fillet need to be that tough?
Click to expand...

Maybe not. It's not uncommon to use micro for very small filets under the glass fabric layups to join T-joints. However, the windshield bond is more dynamic and the install work is the same....so I'll use a flox core, thank you very much.

The reason for the flox core (or micro core, if you insist) under the fabric is stability and resistance to peel. Peel strength is the Achilles heel of composite structure.



marchudson said:
Would the Flox have a tendancy to crack over time whereas the fiberglass might not?
Click to expand...

No, not unless the loads got large. Glass fabric/epoxy is stronger in tension. No surprise; the tension material is glass fiber vs the cotton fiber in the flox, and obviously glass is stronger. However, application makes a difference. Glass fabric/epoxy is anisotropic, meaning it only has strength and stiffness in the axis of the fiber. Flox is isotropic; although maximum strength is lower, tensile strength is equal in all possible axis.
 
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Reinforcement

Hey Marc,

Cement is rock hard too, but ya still need to put rebar in it for proper tensile strength. The fiberglass cloth is acting like the rebar in the cement mix.

Tom
 
Thanks

Guys

Thanks for all the great replies. Lots of useful info. What I did was place a small bead of pro seal at the base of the windscreen. Small meaning about 1/16 of an inch. Then a fillet of Flox was added. On top of that I'm laying glass. I've got about 4 layers on today and plan on putting a couple more layers on tomorrow.
 
windscreen fairing RV8

can anyone direct me to a website of an RV8 builder ...who laid up the windscreen fairing ....removed it for prepping and sanding etc...then glassed.. or sikaflexed back on to the top skin...rollbar etc....rgds stanman
 
Just remember....

marchudson said:
Guys

..... I've got about 4 layers on today and plan on putting a couple more layers on tomorrow.
Click to expand...

....to seriously rough up the dried layups before adding any more or they could separate. A preferred method is to keep on laying up as long as the previous layer is still tacky to wet.

Best,
 
STANMAN;
I met an RV-8 builder during the Arlington Airshow a few years ago that had laid up his windshield fairing over packing tape. He then lifted it off, sanded & finished, then bonded it on for the final. He used Proseal.
He (as I would be) was afraid of scratching the canopy while finishing the fairing.
It turned out superb.
I SIKA'd on both canopy and windshield. I think I would SIKA on the fairing if I decide to use one. Right now my windshield seems well bonded, and the join to the canopy around the roll bar is very fair. I am reluctant to add the 'bump' of a fairing over the top. Perhaps I would add a fairing that only covers the bottom of the windshield back to a nice overlap at the skirt?
If I get a poor rain seal at the top, or the canopy appears to lift in flight, or I'm convinced the top fairing is a safety feature, then I'll do it.
Right now I'm adding a strip of glass to the front of the empenage fairing so I can screw it down to the longeron, like many have done. I have sheet plastic draped @ taped over the tail cone, and packing tape on the horizontal stab.
That's the same way I remade the left rear canopy skirt, which I also used poster board to fill in the skirt shape.
Just keep reading Ken Horton's tips. That's what I did. Nothing I make looks as good as his, but it's all servicable, strong and light.
 
Step by step: non structural fairing on the RV8

This is a non structural fairing, laid up over a hand shaped clay fillet. The fairing is 6 layers of 120-38 (3.16oz) E-glass laid up over a hand shaped clay fillet. Its all done with West's slow cure epoxy. The advantage to this process is that the fairing can be totally finished off the airplane, then bonded on. Our windscreen is bonded in place with SikaFlex; the little aluminum clips you see here are only temp place holders for the windscreen.

Step by step:

Beginning of the clay fillet. Finished out by scraping a radius in place.
windscreenfairing02.jpg


Use your imagination: making a nice transition from the fairing to the canopy skirts here
windscreenfairing01.jpg


Note the edge shape laid out in sharpie pen: matches cut templates
windscreenfairing03.jpg


Final prep step: brushed on PVA release film
windscreenfairing04.jpg


Cutting the E-glass. Paper template used to ensure symmetry between L/R
windscreenfairing05.jpg


Finished product! After an easy release and a little edge sanding, the end result was really worth the effort.
windscreenfairing06.jpg


This fairing will be bonded in place with Proseal. The edges will receive a light sanding and will not be blended as is customary. The idea is to give some extra visual reveal to the entire windscreen area. We'll see!! :D
 
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Am I missing something here?

For a Slider 7 why would you want to glass in the windscreen? Would it not be better to build an aluminum fairing so the glass can be changed out in the future without destroying the paint? Is this possibly a strength issue? One of the first projects I did on my 74 Archer was to change out the glass.
 
@ randy

i think it is just much harder to achieve a nice build, smooth windscreen fairing made of aluminum compared to fiberglass. the fiberglass fairing holds the windscreen pretty good (depends on the number of layers and the quality of bond between the fiber and aluminum/plexi) and in addition you can make riveted strips that hold the plexi and are burried under the fiberglass. so i don't see any reason to make the fairing from aluminum other than aesthetics. and regarding the paint, if the plexi breaks (which is somewhat unlikely) you will have other problems than paint to worry about. but there are some pics of well made aluminum fairings that look really great.

Kay
 
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Scratches

As we all know.. you will end you with scratches at some point and want to be able to change it out, is what I'm getting at. Just go walk around a GA hanger and look at all the really bad glass.
 
hey randy, ok if you feel such a big demand to keep the windscreen replaceable... then just go ahead and make the the fairings from aluminum that is screwed, blind riveted or nailed to the top skin/roll bar and enjoy the metal fairing building process (includes cutting a new canopy)! :)
 
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windscreen

KayS said:
hey randy, ok if you feel such a big demand to keep the windscreen replaceable... then just go ahead and make the the fairings from aluminum that is screwed, blind riveted or nailed to the top skin/roll bar and enjoy the metal fairing building process (includes cutting a new canopy)! :)
Click to expand...

I was just asking if this has been done before and why it is done like it is. It just seems kind of strange to me.
 
It has been done

I did some transition training in an RV-6 that had the windshield fairing, empennage fairing and few other parts that are glass on most planes, done in aluminum. The builder was a real artist.
 
randyintejas said:
For a Slider 7 why would you want to glass in the windscreen? Would it not be better to build an aluminum fairing so the glass can be changed out in the future without destroying the paint? Is this possibly a strength issue? One of the first projects I did on my 74 Archer was to change out the glass.
Click to expand...

Making a fiberglass fairing or skirt that wraps around the base of the windshield and up over the top (with overlap onto the sliding canopy when it's closed) is in accordance with Van's factory plans. If you start looking around, most of the sliding canopy RV's have this. The occasional builder molds it so it is removable, and I've seen photos somewhere of one executed in aluminum, but it's not the norm.

I'd love to have one out of aluminum, but not if I have to make it. At least not this time around.
 
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