For this next step I was very disappointed with the instructions. Why? Well, I made another mistake on the next step. Was it the instructions fault that I made a mistake? Well technically the instructions are correct in the way they are worded, but because of the picture in the instructions it's very confusing and easy to make a mistake. I'm talking about the step were we cut the bottom sheeting so we can install the mounting plate for the aileron servo. If you look at picture #1 you an see the step I am talking about (the second one from the bottom). The text is a little hard to read but it does read to make your measurements for this cut from the main spar, but because the way the picture is situated with the measurements coming from “below” it's easy to get confused and make your measurements from the rear spar. I think that this was a poor choice and placement of pictures on Sig's part when they wrote the manual, but I did make the mistake because the text does say to measure from the main spar. If you remember when we put the wing halves together there was a cut out in both of the W1 ribs for the aileron servo and when you cut the sheeting out your cuts should match up with the cutouts in the ribs. I discovered my mistake when I was cutting across the sheeting and I hit the ribs where there should have been the cutout. I stopped as soon as I hit them to figure out what was wrong. It didn't take too long to figure out the mistake, and correcting it was almost as simple. Since the blade I was using to cut is very thin the actual gap wasn't that much, so I mixed up a little bit of 5 minute epoxy and worked it into where I had cut. If you look at picture # 6 you can see where I cut incorrectly and then used epoxy to fix it. See, I do make mistakes too!! [X(] [X(]
Anyway, back to the build. Once you have CORRECTLY marked the cutout that is needed you'll need to cut make the cuts. I have a very thin razor saw blade that fits in a hobby knife (picture #2) that I like to use because I have such good control over my cut with it (picture #3). If you don't have a blade like this you can use a regular #11 blade with the hobby knife, or you can use a regular razor saw too. Just got slowly (yep, there is that term again.
But it's true just about all the way through the build, going slowly helps to make a better build). Now we need to get the ASM plate as this will be glued into place over the cutout we just made in the sheeting. I test fit the plate and I just wasn't all that happy about how it sat on the sheeting. The instructions called to “Use enough glue to fill in the gap under each side of ASM, caused by the dihedral angle”, but I just didn't like that. IMHO using glue to fill a gap is just poor building practice. So I cut a little bit of scrap balsa strip to fill in that gap. If you look at picture #4 you can see the strips in place on each side of the ASM. Make sure you sand it so that the middle of the ASM contacts the wing sheeting at the center point of the wing. When you are happy with the fit of the ASM we'll need to glue it into place. The instructions called for using slow CA, but this is another place where I felt that epoxy would be better. I very rarely use 5 minute epoxy, but this is a good place to use it. Picture #4 shows the part with epoxy on it ready to be place. Put the ASM in place (picture #5) and then put some weight on it to hold it down while the epoxy sets (picture #6). Once the epoxy sets you can remove the weight (picture #8).
Pictures #8 and #9 show the added balsa strips used to fill in the gap between the ASM and the wing sheeting.
Pictures
1. Referencing the “mistaken” manual. They could have been clearer.
2. Small razor saw blade for hobby knife.
3. Cutting out for the aileron servo
4. Preparing the ASM for installation.
5. The ASM in place. Notice the “mistake cut” below the ASM.
6. Weighing down the ASM while the epoxy sets.
7. The installed ASM.
8. Notice the added strips that fill in the gap between the ASM and the wing sheeting.
9. End view of the ASM. Notice the added strips.
Until next time
Ken