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  #1  
Old 02-22-2020, 08:03 AM
snoop9erdog snoop9erdog is offline
 
Join Date: Oct 2005
Posts: 259
Default For you fiberglass gurus

Iím in the process of laying up layers on the slider Rv9 aft skirt. Iíve prepped the area and closed the gap between the canopy and the aft skin with poster board with packing tape for easy release. The prepped surface appears to be rigid enough and a good surface to start laying layers.

Question: do you cut the layers of fiberglass as one whole piece left and right from the center of the dogbone? My plan was to cut layer sections center over dogbone as well as the skirt layers left and right from the center. Ok to overlap these? And how many layers makes for a thick and stiff enough aft skirt? I was planning on about 5. Should each layer glass be cut in opposing fiber directions?

Thx for any suggestions
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Ed Avila
St. Johns, AZ (SJN)
N646A RV9
Worlds longest RV build...but getting there
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  #2  
Old 02-22-2020, 08:46 AM
wirejock's Avatar
wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,579
Default Skirt

I did a one piece skirt with 5 layers of 8-harness. The aft gap was a bit of a problem. I used scrap pieces cut off the canopy and heavy packing tape. It felt pretty strong and still had a small dip. Inalso molded a doghouse into it.
One long piece is really tough to lay down and conform to the shape. I used three to span the rear section. Seams alternate on every piece. I documented as much as possible to my blog. Tips are on the main page. Details on the skirt are on the Finishing page.
Dan Horton is the expert. Read every thread he has posted.
I just finished the windshield trim. Also a one piece.
Couple of neat tips.
1. Use Yellow Sensitive Surface Gorilla Masking tape as the first layer to protect canopy and airframe. It doesn't leave residue and makes lines easy to see. Draw the cut line on the yellow tape. Lay heavy packing tape over the yellow. Extend further back than you think you need it. Fiberglass and epoxy get everywhere. Use Vans packing paper to mask off the rest. The cut line will show right through the layup. I usually trace the line after a few layers have set. Makes it really easy to get a perfect cut later.
2. If you see a dip in the layup after the first layer or two, mix some thick flox. Spread a bead into the dip. Smooth it a little with a credit card. Lay another layer over it and smooth it out. Flox will move and fill the gap.
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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #3  
Old 02-22-2020, 08:51 AM
622BH 622BH is offline
 
Join Date: Nov 2011
Location: Albany, OR
Posts: 129
Default What I did...

I cut the pieces to fit about Ĺ the length, overlapping at the doghouse. The first layer was standard glass cloth - this eliminates corrosion issues with carbon-fiber, which was the remaining layers.
I put one side down, then the other - with overlapping at the doghouse about 1" to each side. after the first 9 ounce standard glass layer, four layers of carbon fiber were laid up on top of that, with the overlapping building up the doghouse a bit thicker than maybe necessary, but not a significant, noticeable amount.
Cutting all cloth on the 45 degree bias provided a very stiff skirt that has performed quite nicely at about 300 hours.

Looking ahead to the roll bar, I repeated this process, but used about seven or eight layers of carbon-fiber. This was done to eliminate any damaging effects caused by passengers habitually grabbing that area to assist themselves getting in/out of the plane. Even though there are grab-handles, they will grab the skirt more often than not.
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  #4  
Old 02-22-2020, 09:27 AM
snoop9erdog snoop9erdog is offline
 
Join Date: Oct 2005
Posts: 259
Default Aft skirt

Thx Larry and my Oregon friend for the tips. Great info.

I have 2 yards of the 9 oz/yard and both BID and UNI Rutan fabrics from spruce, but I don’t have carbon fiber. I had planned on just using fiberglass and figured the carbon fiber fit that part might be overkill. What do you think? Great suggestion to use it on the front windscreen and roll bar area though. I will do that.

Cutting the sections into smaller pieces sounds smart and easier to lay down and conform.

Did you apply the micro or 410 microlight to the skirt after pulling peel ply while it was still on the airplane or did you apply after removing the peel ply, removing part,then trimming it, then applying the micro and primer to finish out the part?
Just wondering what steps would be best. Or what worked best for you.
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Ed Avila
St. Johns, AZ (SJN)
N646A RV9
Worlds longest RV build...but getting there
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  #5  
Old 02-22-2020, 10:32 AM
wirejock's Avatar
wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,579
Default

Quote:
Originally Posted by snoop9erdog View Post
Thx Larry and my Oregon friend for the tips. Great info.

I have 2 yards of the 9 oz/yard and both BID and UNI Rutan fabrics from spruce, but I donít have carbon fiber. I had planned on just using fiberglass and figured the carbon fiber fit that part might be overkill. What do you think? Great suggestion to use it on the front windscreen and roll bar area though. I will do that.

Cutting the sections into smaller pieces sounds smart and easier to lay down and conform.

Did you apply the micro or 410 microlight to the skirt after pulling peel ply while it was still on the airplane or did you apply after removing the peel ply, removing part,then trimming it, then applying the micro and primer to finish out the part?
Just wondering what steps would be best. Or what worked best for you.
I used this cloth for everything. It took about 2 linear yards to do the entire skirt.
FIBERGLASS CLOTH STAND (8 Harness Satin) 60" wide, sold by the linear yard
Part#7781-60
I know nothing about carbon fiber.
I remove parts and trim then do the finish work off the airplane. There's too much risk of hitting something important with the sandpaper.
I'm still experimenting with finish methods. Last one seems to be working for me. Skim with neat epoxy. Leave it 30 minutes. Spread a thin layer of micro. Sand it smooth but try not to break through. Roll or brush on a layer of primer. Thick enough to be opaque. Sand to 400. Don't break through. Spray primer and paint. I like wet sanding. Warm water with a drop of soap. No floating particles so no respirator.
The odd hole or scratch can be fixed with auto body glazing compound then wet sanded in 30 minutes.
__________________
Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #6  
Old 02-22-2020, 10:41 AM
622BH 622BH is offline
 
Join Date: Nov 2011
Location: Albany, OR
Posts: 129
Default Next Step

Sure, the Carbon-Fiber is not "necessary" for the rear skirt, I just wanted the strength / weight benefit.
I created the "layers" on a sheet of mylar / Poly. Squeegied as much of the resin out as possible without making it too dry. Cut to fit while sandwiched in the poly; peeled the top layer of poly off after cutting. Used the bottom layer to keep the cloth in shape and laid that on the plane. Of course when you lay the other side on, you'll need to remove sufficient bottom layer to allow it to bond to the first side laid down.
Then, repeat - except you remove the bottom layer of poly while using the top layer for support. Once you have the layer in position on the plane, peel the top layer (carefully) away so the next layer can bond properly.

Using a squeegy remove any air between the layers and work your way up to the last layer.

After-cure rimming will be minimized this way. After curing, I lifted the entire skirt off the plane, removed the bottom layers of poly and bonded the unit back onto the plane using SikaFlex. Resulted in a very clean, strong skirt with very little sanding, trimming required.

In essence, the same process was used on the roll bar, though I did make that a one-piece across the entirety. Using the poly sandwich technique permits moving the cloth from layup surface to aircraft quite easy with (if care is taken) no shifting, stretching, or distortion of the cloth.
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  #7  
Old 02-22-2020, 10:58 AM
622BH 622BH is offline
 
Join Date: Nov 2011
Location: Albany, OR
Posts: 129
Default Finishing

Taking advice from a nine-time Lancair builder, I used Hi-Build Primer from Napa Auto parts to smooth the weave surface for painting. The Hi-Build Primer will also take care of air-bubble issues. Be prepared to do a bit of sanding with that stuff, but not so aggressive as to take back down to cloth - just get it smooth using 320 grit.

To get a real tight fit around the doghouse, I used a thick mix of flox to minimize air leakage without making it too tight for smooth sliding. Keeping in mind the nylon "device" will take care of the "Tee" Slider Rail area. I used multi-strand twisted 40# fishing line to secure the "device" to the slider so it will stay with the canopy while moving. The multi-strand fishing line is much lighter and smaller in diameter than conventional fishing line.

Now, as I am looking forward to your "finish" work around the Canopy Latch... I measured a length of that fishing line, attach it to the Latch and back to the first mounting screw on my Koger Shade. This prevents the Latch Handle from rotating forward, which will put one **** of a divot in your Roll Bar Fairing.

Hope all this helps and makes some sense.
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  #8  
Old 02-22-2020, 02:28 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 9,082
Default

Ya'll talking about the flat wrap over the aft edge of a slider?

First make a pattern. Drape a piece of heavy gauge 4-mil plastic over the fuselage-canopy intersection. Tape the ends down on the sides of the fuselage. Cut away most of the excess, re-taping when needed. The goal is to develop a good flat pattern about 3 inches wider than the desired fairing. It's easy to make with clear 4-mil, as you can see through it and draw on it with a sharpie.

No compound curvature to this layup, so ordinary 9-oz plain weave will be easier to wet than a crowfoot. Lay it out on the cutting table, and draw around the pattern perimeter with a sharpie. Outline 4 plies, six if you want it thicker. Cut them out with a pizza cutter.

Lay out another sheet of 4-mil on the table. Stack up all the cut plies neatly on the sheet. Mix, oh, 200~300 grams of epoxy, and pour it all out on the stacked plies. Spread it around and let it soak down through the stack. If it looks like you'll have enough epoxy to wet it all, cover it with another 4-mil sheet and roll the assembly to ensure it is all wetted. Then roll it from center to edges so as to remove as much excess epoxy as possible. Roll the excess to some distant edge of the plastic sandwich. Cut off that section of plastic with the pizza wheel, and toss it, with all the excess epoxy, in the trash.

Lay the template on the stack and sharpie a cut line on the top sheet. Now cut with the pizza wheel, down through the top plastic, the wetted fabric, and the bottom plastic. Peel half the top plastic sheet and cut it off. (Note, there is a stacked and wetted layup here, 3rd and 4th photos: http://www.vansairforce.com/communit...4&postcount=68) Peel the top plastic sheet.

Ready for the layup? Pick up the plastic-backed strip by the ends and fold it in half, plastic to plastic, one peeled half exposed. Position it on the airplane, so the peeled half is semi-stuck. Go around on the other side, reach across, pull the other half of the strip over the top; remember, it still has plastic on both sides, Starting at the top, peel the remaining plastic from the underside, sticking the wet fabric in position as you go. When it's in place, peel the long plastic top sheet. Slick it down (gloved hands work fine), and stipple out any air bubbles with a cut chip brush. Go have a beer. Pop it off after cure and trim to the final size.
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RV-8 SS
Barrett IO-390

Last edited by DanH : 02-22-2020 at 03:02 PM.
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  #9  
Old 02-22-2020, 04:30 PM
Richard Connell Richard Connell is offline
 
Join Date: Aug 2006
Location: Sydney Australia
Posts: 189
Default

Quote:
Originally Posted by 622BH View Post
I cut the pieces to fit about Ĺ the length, overlapping at the doghouse. The first layer was standard glass cloth - this eliminates corrosion issues with carbon-fiber, which was the remaining layers.
I put one side down, then the other - with overlapping at the doghouse about 1" to each side. after the first 9 ounce standard glass layer, four layers of carbon fiber were laid up on top of that, with the overlapping building up the doghouse a bit thicker than maybe necessary, but not a significant, noticeable amount.
Cutting all cloth on the 45 degree bias provided a very stiff skirt that has performed quite nicely at about 300 hours.

Looking ahead to the roll bar, I repeated this process, but used about seven or eight layers of carbon-fiber. This was done to eliminate any damaging effects caused by passengers habitually grabbing that area to assist themselves getting in/out of the plane. Even though there are grab-handles, they will grab the skirt more often than not.
This is pretty much exactly what I did on my -7 slider.
I can report that it was still in perfect condition when I sold it at 10y and around 1,000h TIS.
The only thing Iíd do differently would be to lay a thin cloth or tape over the rivets after its permanently attached to the rear bow.
I had 1 or 2 out of the 30 odd rivets begin to show at maybe 5y.
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RV7 VH-XRC Sold :-(
RV10 in progress.
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