Yeah, I finally got to start building. When you are building there are a lot of tips that can help your building techniques, but there is one that in my opinion is the most important to learn and remember.
“Measure twice, cut once.” Sounds simple, but I see a lot of people really mess things up by not following this advice. When you are cutting take your time, you really can't undo a cut. Yes, you can sometimes glue things back together. But this causes all kinds of problems, so it's easier to just get it right the first time. I will usually measure/mark where I am going to cut. Then I will remove the piece to cut, and then place it back on the plans and measure again to check and see if it's still the same. I don't know how many times I have found that I was off when I made my first mark, and the double check saves me from screwing up.
The first thing done to to double up the main spars. The main spars are constructed from the 1/4”x1/2”x36” hardwood piece and the 1/4”x1/2”x10-1/8” balsa piece. Be very careful when you pull the 36” spar material, because there are two 36” pieces with the same dimensions. One is hardwood and is used for the main spars in this step, and the other is balsa and is used elsewhere. It's easy to use the wrong piece in a situation like this, but that could cause major problems. The hardwood is used for the spar and it is this piece that is the backbone for the entire wing, if you use the balsa piece here by mistake the wing will end up being weak and will likely fail in flight. Glue the smaller piece to the end of 36” hardwood spar and clamp the two together until the glue dries (see pictures). Once the glue dries you can remove the clamps and proceed to the next step.
Locate the main spar on the plans and pin it to the board in place. Make sure the inside edge of the spar is accurately located on the plans. Take extra care when securing this spar to the building board. The entire wing will be built off of this spar and you don't want it moving around as you built, this would result in a wing that is warped or crooked. Once you have the spar completely secured you will cut it even with the outside edge of the outside rib. Use a razor saw to cut this off (and remember “measure twice, cut once”).
Find piece WS-B2, which is a piece of sheeting. This will be placed between the main and the rear spar. For those using CA, you'll put this piece in place and then run CA along the front edge where the sheeting meets the main spar. For me using wood glue I place a bead of glue along the edge of the sheet and put it place. Once I have it in place I'll use magnets to secure it in place.
Locate the 1/4”x3/8”x36” balsa stick used for the rear spar. According to the plans this piece is supposed to be done the same way as the main spar, in the fact that the spar is secured on the plans and then is cut at the outside edge of the outside rib. I did that procedure on the main spar only to show how the instructions tell you how to do it. I don't like cutting it in place because it's hard to cut without loosening your magnets/pins, it tears up the plans underneath as you cut, and it's hard to cut it straight (see attached picture). For this spar (and the rest in this build) I placed the spar in place on the plans and then I marked where the cut should be (remember, measure/mark twice- cut once) and then used a miter box and razor saw to make the cut.
Although it wasn't listed in the “nice to have” list of tools you should consider getting a miter box. This let's you make very straight cuts with a razor saw and will help improve your build. I like the new Midwest (shown in pictures) miter box because it's got cuts for 0°, 22.5°, 30°, 45°, and 60°. And it also has a grid of holes inside the box and there are three pegs that can be used to secure your work while you cut. I highly recommend getting it.
Ok, once the rear spar was cut to length I went and put it in place. The rear spar needs to be glued to the bottom sheeting that was put in place earlier. I marked where the piece will attach, and placed glue on the rear spar. I then secured the rear spar to the plans, making sure it was completely straight across the length of the wing. Just like the main spar, the rear spar needs to be straight and kept secure in order to build the wing properly.
One thing that some people won't do when the to a build thread such as this is admit when they screw up. In the spirit of hoping that others will learn from my mistakes, I will admit to a screw up
. Although it wasn't a huge one. When the WS-B2 is in place it is actually the sheeting for the skin of the wing, therefore it should be on the outside of the wing surface, and flush with the spars that it is attached too. When I put the rear spar in place, and glued WS-B2 to the rear spar I didn't have spar tight against the building board. Because of this WS-B2 wasn't even with the outside edge of the rear spar. Luckily I noticed this before I went any further, and I was able cut the rear spar away from WS-B2, reposition the parts, and re-glue them. If I hadn't noticed it at this step the only thing I would be able to do later on would have been to sand and/or fill in the mistake. So, I got lucky and I was able to correct the problem.
Pictures
1. Applying glue to 1/4”x1/2”x10-1/8” balsa piece before glueing it to the 36" main spar
2. Main spars clamped while glue dries.
3. Sawing off the main spar.
4. Applying glue to the edge of the first piece of sheeting
5. Example of crooked freehand cut
6. Midwest miter box. Makes getting straight cuts very easy.
7. Securing the WS-B2 sheeting.
8. Both spars, main and rear, in place secured to the building board.
9. A look down the spars from the inside edge of the wing.
10. A look down on spar from above. This shows the alignment on the lines printed on the plans.
11. A look down on both spars from above.
12. Both spars and sheeting secured in place.
Until next time
Ken