I guess I owe everybody a little apology. The “real world” stepped up and stopped my from posting the rest of my progress. First off, I had a really good day at the flying field. The weather was just about perfect, so of course I had to stay out and get in some extra flying. Then after I got home a couple of problems at one of my clients kept me working for the rest of the day, and into the night too. So I wasn't able to back on here to finish catching up posting the build. So, let me take a bit of time and finish catching up my postings to where the build is at.
In my last post I described setting the ribs by using a ruler to measure the distance between the notches on the Trailing Edge (TE), and marking that same distance on the 2 spars. Now we'll talk about the easier way of doing, and that is using the shear webbing to space our ribs. Even though I showed both ways of placing your ribs, this is probably the best way of doing this. This is because you want a tight fit of your shear webbing between each rib. Even when doing very accurate measuring it's possible to be just a bit off when marking. We're all human, so it's possible to be a bit off. By using the shear webbing to place the ribs we can ensure a tight fit between the ribs because we will be gluing the ribs in place by butting them against the shear web. We should have the first W5 rib in place so far. Before we start placing the remaining ribs, let's take a few minutes to catch up and place the shear webbing between the ribs that we have in place already. On the main spar we are going to place a SW-2 shear web between ribs W3 and W4, and on the rear spar a SW-3 shear web will be places. Apply glue to the sides and the bottom of the shear web and put it in place between the ribs.
NOTE: Since the shear webbing is an important structural component of the wing you want to make sure there is a very good joint here. This is no place to skimp on glue. I recommend going along the bottom of the shear web where it sits on the spar and put in a fillet of glue along the length of the web, with fillet meaning putting a bead of glue into that joint (if you are using CA for your build you will want to use medium or thick CA to do the fillet). I can't stress enough the importance of having a good joint with the shear webbing. Also, remember from our discussion of shear webbing in previous posts, the important joints are the top and bottom joints where it joins with the upper and lower spars. I do however recommend that you also make a good joint on both sides of the webbing where it meets the ribs.
Now place the shear webbing between W4 and the first W5 rib. You will use another SW-2 on the main spar, and a SW-3 on the rear spar. Gluing it in place will be identical to the first one that we did. Once we have that we are now “caught up “ with the ribs that we have in place. Now we will use the shear webbing to place the next ribs. It's a pretty simple procedure to do them. Even though it's easy, I try to pay extra attention on tasks like this because it's the easy tasks that I get sloppy and make mistakes. Starting at the W5 rib that is in place put a SW-1 shear web on the main spar and a SW-3 shear web on the rear spar. With these in place you can now set the next W5 rib. Of course we should dry fit everything before actually using glue. (“Measure twice, glue once”). The last SW-1 shear webs that will be put in place will be in the 3rd bay from the end of the wing (2 open bays with no webbing), and the last SW-3 shear web that will be in place will be the 4th open bay (3 open bays with no webbing) (see picture #8). Once we get down to the last shear web we are back to measuring the distance for placing the ribs. As you place the ribs in place make sure that you keep using the 90° brackets on each rib to keep it perpendicular, you can see these brackets in us in pictures 4,5,6,7,8,9, and 10. It doesn't hurt to check each rib with a square also as you install the ribs. Trust me, it's a lot easier to double check everything as you build than it is to un-do a mistake (voice of experience talking here!!!!
).
Once you have the last W5 rib set this is a great time to take a break. I said, take a break. Yep, put your feet up and relax for awhile. Why so pushy? Because it's really easy to get moving too quickly. Once you get into a groove it's easy to “get addicted” to progress, you want to finish more. This is when huge mistakes start happening. I like to take a break every half hour or so, and I try to not work late into the night, because mistakes happen when I get tired. And besides, it's time to let all the glue to dry on all of the ribs before we place the top spars and the leading edge. Pictures 9 and 10 show where we are at right now.
So let's take a break for now.
Pictures
1.Getting ready to place shear webbing.
2. Shear webbing SW-3 in place on rear spar.
3. Showing shear webbing on the main spar.
4. Shear webbing SW-1 in place on main spar
5. Another shot of SW-1
6. A set of ribs with shear webbing in place between them.
7. Shear webbing in place and ready to place the next rib.
8. Locations of final shear webbing.
9. A shot of all ribs in place.
10. Final ribs in place.
Until next time
Ken