|Wing Root Fairings:|
A majority of the Glasairs that I have seen at air shows have shown great attention to detail in their finished appearance. The only problem that I keep seeing is that everyone is installing the Glasair 1 wing root fairings with safety wire. You would think that the builders manual had instructions on how to do it this way. I mean, really, safety wire? Holding parts on such a beautiful aircraft? Safety wire should only be used to hold a bolt from coming loose or a cable from slipping or some other hardware part in the event that piece of hardware fails. NOT on the outside skin of the aircraft. What? You say that the builders manual DOES have you install them with safety wire? Well, not my plane.
In hindsight, I'm not sure the effort will be worth it to everyone. After talking to a couple people that have ridden in Glasair 1 aircraft, this installation method may solve another issue. They say that the fuselage sidewalls tend to move during flight and that this can be rather disconcerting to some people. This mod definitely took the flex out of the sidewall. I went for it based on these two reasons.
First I rounded up the wing root fairing instructions from a Glasair II. After reading it I determined that this is a much better way to install these fairings on my plane.
The first step is to mark the top of the wing at the inside fuselage sidewall. Then remove the wing from it's mounts. I chose to lower it to just below the fuselage opening. I figured I would be raising and lowering it a few times and I didn't want the fuselage to get lost. I made a second mark on the wing 5" further out from the fuselage marks. The wing flaps have to be rigged into proper position for cruise flight. I had my flap motor and linkage installed to hold the flaps in place. I installed 4-5 layers of duct tape to the upper skin of the flap where it would be tucked under the fuselage fairing. I also added a piece of foam to extend the end of the flap to support the laminate. Then I installed 4-5 layers of clear tape (be sure it's compatible with vinylester resin) over the wing in the area between the marked lines overlapping outside of the marks about 1" and continuing over the flap and duct tape.
The next step is to apply a 4-layer laminate over the tape. This has to overlap the lines completely. The photo makes all of this much clearer. The duct tape is just over the inboard edge of the flap. This laminate will be trimmed back almost to the duct tape before we are done. Don't worry about that yet.
After these laminates cured it was time to trim them so we can put the wing back into place. To do this, I raised the wing closer to the fuselage. This trimming doesn't have to be exact, just so the laminate clears the fuselage sidewall by no more than 1/16" or so. This area will be reworked after the main fairings are done.
After trimming the laminate, apply tape to the outboard edge to hold it snuggly to the wing surface. Next remove the foam from the fuselage sidewall up to about 1/4" at the wing opening. This area will get packed with milled fiber to attach it to the 4-layer laminate. Now I raised the wing into place and marked the top and bottom surface of the flap onto the fuselage sidewall. I lowered the wing and removed the gel goat for 1" outside the area marked, over the top of the wing and over the front just to where the belly panel starts. Now I raised the wing into place and installed the mounting hardware.
You can see that I didn't do a real good job when I cut the wing opening out. I left too much room. This turned out to help in the next step. The milled fiber has to be put into the recess in the fuselage sidewall and the wing raised into position at the same time. Then apply tape to the inside edge of the fuselage to create a dam to keep the milled fiber out of the cabin area. Next, from the outside, pack the recess with milled fiber creating a nice radius on the outside of the fuselage at the laminate intersection. This is done from the front of the belly panel opening, over the top of the wing and back to just ahead of the flap. After the milled fiber is complete a 2-layer laminate needs to be placed from the fuselage sidewall onto the top of the 4-layer laminate. Now it can be left to cure.
Once cured, the top surface of the 4-layer laminate needs to be sanded smooth. I should have used peel-ply, but I was in too much of a hurry to think about it. The non gel-coated side of the pre-molded wing root fairings just need to be smoothed out to an even thickness for the next step.
At this point, I followed the Glasair 1 instructions for sizing the fairings over the laminates. Once sized, I temporarily installed them with clecos. The cleco holes will be filled later. I marked the sides of the fuselage along the top of the fairings and along the bottom under the flap area. At this point, they look too pretty to mess with anymore and the wire tie idea starts to look like a real easy way out. Just remember, we've come too far to stop at this point. The end result is much better than this.
I removed the fairings and sanded the top surface of the 4-layer laminate. I also removed the gel coat for 1" outside of the fuselage sidewall marks and 1" on both top and bottom edges of the fairing. The hole for the wing mounting hardware has to be cut at this point also. These will be dealt with later, so a rough hole just large enough to get a socket in will be fine.
The next step is to permanently attach the wing root fairing to the fuselage and 4-layer laminate. The lower portion is attached with milled fiber squeezed between it and the 4-layer laminate and a 2-layer laminate over that. Install the clecos to hold the fairing in place while curing. The upper portion is attached with a 2-layer laminate that runs from just ahead of the belly panel, over the top of the fairing and back under the flap extension. This is what it should look like.
Now for the wing mounting hardware access holes. First I had to determine the outside diameter of a socket that would fit the bolt. I ended up with an inside diameter of about 7/8". The front mounting screws use tinnerman washers. If your socket is smaller than these, be sure to make the fiberglass tube large enough for the washers. I used a dowel that was just over this size, applied tape to it and laminated a 2-layer laminate over the outside. After it cured, I cut this tube and installed a piece of it inside each access hole. These consisted of one deep hole at the rear attach point and 2 shallow holes at the front lowest screw attach points. They are held in place with milled-fiber.
The rear flap transition was the most difficult part of this modification. There are several ways to create a mold on the side of the fuselage to build these. I chose to eliminate the flap to fairing overlap. To do this took some interesting work.
First I removed the wing from the fuselage. I mounted the fuselage in the jig upside down to make it easier to work on these laminates. I put the wing in the roll over fixture and turned it upside down. Next, I used an engine hoist to lift the wing out of the rollover fixture and jigged it into place in the upside down fuselage. I guess you could say my plane had it's first inverted flight.
After everything was jigged into place, I set the flaps to the cruise position. I taped over the flap and wing so that laminates wouldn't stick to them. At this point, I draped wetted out cloth onto the fuselage, over the gap between the fairing and flap and onto the flap. I used a little finesse to get a natural shape to the drape. After that cured, I applied another 3 laminates to give me some room to sand the final shape. I removed the flap first, then removed the wing. The flap left a nice mold line on these laminates. After trimming to this line, I used scraps of pre-cured laminates to close out the front and sides of the transition area.
The last work left to do on the fairings was to clean up the edge where the fairing and 4-layer laminate meet. This is left to the individual to shape. Then I used body filler to fill and smooth the transition from the fuselage sidewall onto the fairing. A rolled up magazine with adhesive backed sandpaper, about 2 days sanding and filling then finally primer resulted in the final product.
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