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Old May 29, 2012, 07:18 PM
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United States, CA, Los Altos
Joined Feb 2012
228 Posts
Update

I've gone back and filled in a few details.

- I've created a small fillet on the bottom leading edge of the wing, to fair it into the fuselage. I probably should have done this before I primed the wing, but my thought was to leave it until later to both allow for completely unrestricted sanding of the leading edge (otherwise the fillet would interfere with block sanding in that area) and also to only build up the fillet after finalizing the wing saddle area, which effects fit of the wing and thus size of the required fillet. I'm happy with the result, though.

I first taped off the fuselage and surrounding areas of the wing, removed the primer under the fillet, and built up a first pass with 45-minute epoxy with a large dose of micro-balloons to make a sticky putty. I used a scraper coated in denatured alcohol to form the initial shape of the fillet by simply bridging the gap between the bottom forward lip of the wing saddle (which projected below the wing leading edge by about 1/8" at the deepest point, right at the centerline) to the area at the aft edge of the landing gear box. I made sure that, if anything, I slightly underfilled at this point because I didn't want to spend a lot of time sanding... this stuff gets pretty hard when it's fully cured even with all the micro balloons!

At the same time, I filled up the bottom horizontal leg of the landing gear with the epoxy mixture, to fair it out all the way to the wing surface. I Scotch taped around and into the forward and back edges of the little landing gear box I made so that it wouldn't stick. This made a nice fit fore and aft on the landing gear fillet, and the gear popped out nicely when the epoxy cured. This fillet does nothing more than fill up the landing gear box... it does not protrude aft beyond that onto the wing proper as it doesn't need to, to make a smooth contour from the fuselage saddle lip.

After another spot application or two of epoxy/micro balloons, and a final layer of Bondo putty which was mostly sanded off to fill any remaining irregularities, I topped it off with a layer of 3/4 ounce cloth faired right into the finish. I also put 3/4 ounce cloth on top of the fillet on the landing gear. With a spot coat or two of primer, the wing can now wait for final prep prior to painting.

- I then drilled back out the 1/4" holes in the landing gear (going through the epoxy fillet in the gear itself) and countersunk to accept the 1/4-20 nylon bolts supplied in the kit. I had also previously drilled and tapped the receiving blocks in the fuselage, and also countersunk the location for the rear bolt (which is a 10-24). As the fillet on top of the landing gear is very thin around these bolts, about 1/16th or so, and the bolt heads are 1/2" wide, the countersink goes right through to the very base of the aluminum gear. Best done with a drill press on slow RPM.... which I really need to purchase one of these days... Seriously though with a regular power drill (no press) it's very hard in general to stop chattering. In this case, I did just use a power drill and the aluminum gear itself provided a solid enough material to prevent chattering and gave a clean countersink. For the aft holddown, though, where there is only a dowel, I found the best way was to literally twist the countersink bit completely by hand to get a good result.

This is all pretty similar to Terry's instructions, except that Terry never tells us if the gear itself is left removable or if it is permanently glued into the wing. I've made mine removable, but that's only because I didn't feel I could get the finish I wanted around the base of the gear if I built the gear into place. However, I've left the fillet over the aluminum landing gear bonded to the landing gear itself because it's so thin... 1/16" max at front and about 1/8" max at rear (I was originally pondering whether this, too, should be removable).

- Finally, I've glassed the stab, elevators, fin and rudders both sides with 3/4 ounce glass cloth. I'm beginning to love this stuff again, when it's done right it really comes out nicely. I also laid in a strip of tow top and bottom on the stab under the glass just for fun, though hardly necessary (it did make the stab virtually unbendable though!) The trick with this fiberglass cloth, as always, is how to handle the leading and trailing edges. More to come later!
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