Canopy Skirt finishing

As is often the case, I have been chugging along slowly on my RV-3. The latest chore was laying up the canopy skirt which went surprisingly well, however, my dreams were mostly shattered when I sprayed primer on it. What a mess. The primer highlighted how uneven it is and how much the weave shows thru.
Question: how is the best way to proceed? How is the weave best filled? Is it best to use a product like Superfil, or would Bondo be the best to fill the hollows?
Would appreciate any suggestions.

Bill NEWKIRK

I know the feeling. The cheapest and easiest way is to use a mixture of glass microballoons and west systems 105 epoxy. You can mix a huge tub of it to coat the entire thing.

RV3 canopy skirt

I took a couple attempts at the fiberglass/epoxy/resin canopy skirt before discarding the mess and going with

metal

This skirt has 6 individual pieces, .032 2024-T3:

- a piece around the front
- a piece around the back
- 2x flanges next to the canopy sides
- 2x large flat sheets laying on top of the flanges and frame

The two flanges need stretch-forming to make the only compound curves in the assembly - use a smooth hammer and bucking bar in a vise, hammer and fit, then smooth it out with 220grit paper.

flush-pop rivet the large flat pieces onto the frame. Use #6 screws through skirt, canopy lower edge, then into the backing tube on the frame. Then oversize drill the holes in the plexiglass and insert little plastic donuts that the #6 screws go through, and the entire canopy floats on a bed of soft plastic.

- Steven
800+ RV3 hours
(two more last weekend!)

I'll add a hybrid way of doing the RV-3 canopy

1. Read the threads on here and decided not to even bother with the Vans metal skirts
2. Made up, using "packing tape", a mould surface/transition between canopy and fuselage
3. Laid up 2 layers of glass on 1 side on this...

Conclusion was the areas in front / rear of canopy were good, but the large panels at each side needed a better approach... at which point I noted these areas were less complex curves, so used the Vans skirts here.

Summary: between (and ~1" beyond) the 2 canopy frame verticals I have used the AL skirts. For the 1"-3" flanges right round I have used glass, bonded to / riveted to / faired in to the canopy / metal as required. 90% done and the fairing in above still to be done, but happy with the result so far (progressed from this pic, but trust you get the idea):

If you are a composite expert, then I would think all composite is the way ahead. Steven is clearly a true RV builder, and loathes anything to do with glass If you are somewhere between, maybe my hybrid approach appeals

NB 1/8" Pop Rivets into canopy frame verticals, solid rivets along bottom, 3/32" Pop Rivets to hold glass/metal bond in place

N13BN said:

Question: how is the best way to proceed?

Click to expand...

http://www.vansairforce.com/community/showthread.php?t=22931

Canopy Skirt

Thanks for the replies. Dan, I had read your post in the past but was unable to locate it again when I needed it most. I am using Rob's suggestion of micro balloons and epoxy. Probably my biggest problem is that I am lazy and hate sanding. The fiberglass layups are fun, but the sanding sucks. My wife says "cowboy up". I hate it when she is right.

Bill Newkirk

Metal canopy skirs

Steven, I am really impressed that you were able to make the metal skirts work. I tried that first but my efforts certainly didn't match yours. How were you able to get the front to seal?

Bill NEWKIRK

They key with sanding is to select the right grit. Start with 60 or 80 to rough it into shape then work up to 320 before primer.

metal

It's a butt-seal in front and all around. Cut & sand, shut canopy to fit. Repeat. Then glue on rubber molding to seal (shown in the photo). No air or water gets in.

- Steven
(800 RV3 hours -
no flying today, 23ktG42 at my home airfield!)

Dry micro

Dan, in your excellent post you mention "dry micro". Do you mix it until it seems about right, or is there some more scientific way to get a consistent result? I am concerned about getting different percentages of epoxy in successive batches. This would tend to make some areas harder to sand.

Bill Newkirk

N13BN said:

Dan, in your excellent post you mention "dry micro". Do you mix it until it seems about right, or is there some more scientific way to get a consistent result? I am concerned about getting different percentages of epoxy in successive batches. This would tend to make some areas harder to sand. Bill Newkirk

Click to expand...

Very good Bill. There should be no successive batches.

Different density with different batches will indeed result in uneven sanding. Always apply a reasonable excess with the first application. It may seem to add sanding time, but in truth it's faster than repeated applications to correct low spots, and way less time to get looking good.

In general, mix fill micro as "dry" as possible. It should be spreadable, but not run off the mixing stick. The ratio is something like 5 to 1, micro to mixed epoxy, by volume. More dry is easier to sand, more epoxy is harder. You can develop a recipe if you want, but why bother for a one-time small project?

Wear a dust mask when you mix micro. Microspheres are light enough to float in the air and you'll breath them.

Microspheres are great insulators. If you mix a batch of micro and leave it in the container more than a few minutes it will exotherm, i.e. the cure heat of the epoxy can't escape and you'll get a thermal runaway in the cup. Lay a sheet of 4-mil plastic on the bench, mix the micro, then dump it all out on the plastic and spread it thin. Cure heat will now be able to escape, so it won't exotherm, and you'll have time to work it. Tomorrow, any waste micro will pop right off the plastic.

Obviously, use slow hardener.

We are having a nice stretch of 70* weather so I took the opportunity to try to mix and apply a batch of "dry" Micro. After I spread it out I realized that it could have been much drier. It sanded pretty well but took quite a lot of elbow grease.
By the way, Dan's tip about spreading it out on plastic in order to slow the cure rate was truly a winner. It was something that I never would have though of on my own. Thanks.