|Upper Wing IX|
|Superfil finally done...|
I am now almost done with the upper wing [I know I know...I keep saying that, but new tasks keep appearing out of nowhere]. The leading edges are now glued on, on the underside [pics show wing bottom-up]. I figured it would be easier to glue one side, turn over and complete the other. While gluing the first side, I ensured that no glue was near the nose of the ribs - the last thing I need is a small stray blob of T-88 working its way down the rib during curing, thus creating a cavity/high spot when trying to clamp up the other side.
To clamp, I ripped down the excessively [that's definitely a compliment bye the way] sturdy freight box that the LE's were delivered in from Steen Aero - 3/4" white wood of some sorts, and stapled at intervals to the ribs and spar fillers, ensuring that the staple lengths were short enough so as to not touch the actual spar. To feather in any high and low spots, I used a 4ft piece of alum' angle with a 1 inch sanding belt stuck to it with double sided scotch tape. A laminate trimmer was used to trim the excess at the rear of the LE's. I then added 5" x 1/4 feather strips on to the ribs immediately aft of the LE, so as to transition the step-down caused by the 1/16 LE ply. A block plane and sanding block works well for the feathering.
For some reason, this batch of LE birch ply was very absorbent, and it took 3 coats of Clear Coat to finish. Maybe my first coat was spread too thin. However, thin/more coats are better because Clear Coat does have a tendency to sag and run if applied too thickly.
I then finished up the wing tips with a couple of layers of Superfil to create a smooth transition from the ply to foam, and Clear Coated them. Now all I have to do is turn the wing over, and repeat all of the above :0| then I really will be finished with this stage.
I was going to leave the center bay ply off until after rigging, but seeing as I had a nice flat bench with no twist anywhere, it would be a good time to do it [plus I felt it would add a little more stability during wing-moving]. The plans call for 1/8 ply in the center section, and it seems it's fitted internally between the ribs. I wanted a good transition from the center LE ply to the center section, so I first made a 1/16 piece to fit internally between the center section aperture. This was tricky, but I eventually got it to fit like a glove. This was then laminated to another 1/16 piece that was oversize, then the whole deal was glued on to the top of the surfaces, which will result in a smooth transition once the center LE is fitted after initial rigging.
I also added a couple of nose ribs to provide support for the center LE. Once the wing is turned over and I can get to the inside of the center section, I may add several very small gussets where the ply mates to the ribs and spar fillers.
Supplementary nose ribs...