Today was the day to smear the top of the left wing. I am still amazed at just how much of a visual transformation it is to have a large surface all white. I am so very thankful for how much time Greg has been putting in with me lately. He was here from 0900 to 1700, and it took all of that to get the wing and strake covered in micro.
The morning started with Greg prep sanding the carbon ‘wing walk’ and surrounding areas. While he was doing that, I cut out the remaining two aluminum seam forms and put 4 coats of wax on them. Just like the bottom side of the airplane, these serve to mold in the seams so they are straight, and constant gap.
I was also able to cut out the hole for the oil check door. This left a quarter inch flange all around the perimeter of the door. You can see that ideally this door would have been slightly more inboard, including the radius for the center hump. The dipstick is off to the inboard side of the opening. It does come out, but if the dipstick is tight, it may be difficult to get your hand into a position to apply the required torque. We will see how that goes, I have a few ideas if it ends up being an issue.
We were debating how to mask off the fuel filler cap for micro application when I came up with an idea. I had a poster shipping tube which was just slightly smaller than the fuel filler opening. I then wrapped that with 1/8″ sheet wax. It turned out to be the perfect diameter. So we used that to create a perfect circle around the fuel filler. The adhesive ended up not being strong enough to keep the wax in place, and so we added aluminum tape around it to keep the wax in place.
We had everything ready to go for micro by noon. So we broke for lunch and then got to work around 1300. It took us from 1300 until 1700 to apply the flocro and micro. Greg mixed the whole time, and I applied the fill. The mix I use is 4 pumps resin, 4 pumps hardener (West slow), and 3 dixie cups of micro. It turns out to be just right.
Flocro went along all the seams as well as around the fuel filler cap, micro everywhere else. The flocro gives a more durable edge anywhere where pieces are removed/installed.
I do have to say that I am learning more about applying the filler. One thing was from a suggestion from Terry Schubert. If you heat the back of your putty knife with a hair dryer, set on low, it makes the resin just slightly less viscous and it spreads MUCHO better. The surface finish is much better, not as many tears. The heat also allows you to mash and ridges back into the surface. Of course it is still an exercise in knowing when to just leave it be.
BUILDER TIP: Another thing I learned today, that I haven’t read anywhere else yet is to apply your micro in the same strokes as you would use to contour sand. That is to say, keep the edge of your putty knife parallel to the span line of the airfoil. Then drag your putty knife, using moderate pressure and a very low angle, on a 45 degree angle to the span line. This allows you to keep a relatively consistent thickness of fill and also allows you to blend as you progress along the span. Go over the filler in both 45 degree directions from both the fore and aft side of the wing. Another thing this does is ensure there are multiple directions that the micro is flowing. That helps to fill in any air bubbles and voids. It also helps to prevent digging the edge of your knife into the filler.
Another thing I did was fill the winglets without cutting the rudders out. The corners of the rudder were drilled with a very small drill. Then toothpicks were inserted in these holes. The toothpicks will sand during contouring, but also show a different color, allowing for accurate locating of the rudder.
Well, without further ado, here are the photos of the top of the left wing and strake.