RV-8 Canopy Skirt Data

[pvalovich]

I'm engrossed in the canopy skirt phase of my RV-8A construction and have run into a couple issues where I've found partial answers.

The first deals with forming (rolling) the skirts to get a better flat set against the fuselage and canopy rail. No heat, a little heat and more heat didn't produce a noticable bend in the curve. A lot of heat (from a heat gun), along with a lot of muscle, produced a small change. Question is, when applying localized heat to a large epoxy part like the canopy skirt - how much heat is too much? And what are the bad things that can happen?

Second, I'm aiming for a no-gap finish all around between the skirt and fus / canopy rail (I glued the canopy and will glue the skirt). I've got about a 1/16 inch gap along about 3-4 inches of the bottom of the left skirt, and 2-3 inches along the top. Is it ok to declare victory - or have folks actually gotten the thing to set flat all around?

Of course the devil's in the details - 95% of the time trying to fix the last 10% of the procedure.

 

[N208ET]

I left a little

I have about 3/32" at one point on my skirt for a 4 to 5 inch span. After looking at a couple other 8's with that gap, I figured I could live with that. But if its perfection your after, you might have to do a little cutting. I tried the heat gun method with little success. I know I was heating the fiberglass almost to the point of making it black and still couldn't get it to bend.

 

[444TX]

skirt

Paul

The skirt to fuselage side clearance is easy to fit. With a cutoff wheel or perma-grit wheel in a dremil tool cut a slice at the bend line. Slice on the outside 95% of the way thru. Do not worry if you go thru in places. You now have a hinge and can bend the bottom flap made on the skirt against the fuselage and re-glass the skirt to the fuselage shape.

The rear is more work. I made verticle cuts and horizontal hinge slices as needed to get the skirt to lay flat on the fuselage. Then glass and smooth the skirt back together. This may need to be done all over the skirt to get things to look good.

You can obtain a perfect gap if you are willing to spend the time. There is actually little work time and more spent waiting for things to setup/dry. Spend a little time cutting, sanding and glassing everyday. Do something else while it all sets. In my experience heating is of little value. Cut, add, remove material for a good fit.

Stive for perfection, but settle for excellence.

George Meketa
N444TX, RV8 950+hours

 

[scsmith]

alternate approach

As an alternate approach, I cut the skirts at about the back-seat bulkhead, and threw the aft parts away. I ground a scarf angle on the trailing edge of the sides, fit them to the canopy frame. Then, I made a form from posterboard and packing tape, on the fuselage and canopy for the aft half of the skirt. I put three plies of glass, then covered with a thin layer of microballoons, sanded the whole thing fair, then put three more plys of glass. I ended up with as nearly perfect a fit as one could hope for. It was, I think, about the same time investment, and a lot less frustrating.

Because of the way I extended the glass a 1/4" below the posterboard skirt pattern, onto the fuselage, I have a 1/4" wide mating surface on the inside of the skirt against the fuselage, all the way around the back. On the outside contour, this lip was filled with the micro and sanded to a straight contour so it doesn't show.

I found that when I glued the skirt on with Sikaflex I didn't get it in precisely the same position that it was cast in. It would have been good to put one or two clecos through the skirt, canopy, and into the frame. I was scared that I would not be able to hit the center of the frame tube, so I didn't do it. But I should have. It still fits fine, just not as perfect as it was before I glued it on.

Oh, a tip on gluing the skirt with Sikaflex - you need something to maintain the glue gap between the skirt and the canopy. I didn't want a really thick glue line, and it is more of a weather seal than a structural attachment, but I wanted the gap to be nice and even. So I used a single thread of 50-lb test nylon fishing line, tacked to the canopy with superglue every few inches. The line runs along about a 1/4" below the lip of the skirt, and maintains a glue gap of about 0.030 or so. It stays in there when the whole thing is glued on with Sikaflex.

One thing I didn't account for is that when the canopy latch closes, it pulls the whole frame slightly to the left, and disturbs the perfect fit slightly. I think I will open up the latch hook a bit and have it latch less tightly so it won't pull sideways, I hope.

 

[Rick6a]

.........In my experience heating is of little value. Cut, add, remove material for a good fit.....George Meketa...

Listen to George. He obviously speaks as someone who has been there, done that. All too often, reshaping fiberglass components with a heat gun is just not practical solution. Imagine my initial horror when discovering the rear portion of the skirt was hopelessly out of whack during the initial fitting. With a little work and by the end of the next day, 95% of the gap was taken care of. Don't be afraid to snip, cut, trim and reglass. It is true you will spend more time waiting for epoxy to cure than actually dealing with the problem.

 

[grover]

add material

I got lucky on one side- - it fit ok by itself. but had to add some material on the other to get a good, close fit. lots of iterative (ie, time consuming) addition, sanding, repeat. . . .

 

[Wiley]

is aluminum an option

I'm sure fiberglass is used due to the difficulty is forming the skirt from aluminum. That being said, has anyone made a skirt from Al sheet? This would look really nice on a polished plane.