From the last post I was making up the rear handrail that runs along the rear of the top wing centre section. In this post you will see the fitting of the rail to the rear section. It required trimming the hand rail itself and sanding the profile into the trailing ribs from the rear spar. I can see that the gap here particularly in the outboard bays will, once some supporting blocking is added will need to be filled with foam and glassed to get a smooth solid surface for the fabric to stick to. Of course that will be later as I won’t be doing any more to this section now until it is trial fitted to the fuselage.
In the photos above you will also notice that I have trimmed and prepared the bottom section of plywood. This will provide structure for the “box” that is the centre section. In addition it will contain the large (relative to the standard Skybolt) upper fuel tank.
The piece of timber laying on top (though the centre section is on the bench upside down) is the first of three laminated stringers that run front to back and screw into the spar. This will provide further strength to the front leading edge, centre section bottom ply and add rigidity to the complete centre section.
OK a quick tutorial on how to make wooden wing ribs.
Step 1: If you want to do this the easy way…. but a wing rib kit from Steen (if you are building a Skybolt) as well as the rib jigs. If you dont want to buy the gussets, capstrip and jigs – thats fine you can make them, but man that would take a lot of time
Step 2: From here I am using a rib kit and the jigs. Next step is to lay some Glad Bake into the jig. This stops the glue sticking. Then cut out the gussets from the sheets that come with the kit. One sheet per rib. It does take a bit of tim to figure out which of the 6 jigs to use. Once you have done a couple you can figure that out. You will notice in the picture below that the nose rib is already cut – another time saving from the kit.
Step 3: Trim Capstrip and lay it in. You will notice that you need to notch the fronts of the top and bottom cap strip to lock it into the nose rib infill. Trim the rest. I do the verticals first then the angles.
Step 4: Glue. Now once its laid in, I pull it all apart again to start the glueing process. I do one rib in about 35 minutes. Each piece needs to have glue added in the right spot in the joint starting with the bottom gusset, then lay the cap strip in then add the top gussets.
Step 5: Lay another sheet of Glad Bake on top of the ribs, ready to sandwich between the bottom of the jig and the perspex overlay
Step 6: Place the top on and clamp to hold flat. Once clamped drying only takes about 12 hours.
Step 7: Once dried and removed from the jig, there is quiet bit of sanding that is required. What I have done is use a file with the jig in a vice to file out the spar location holes, then used a linisher to sand any glue on the outside of the rib. Any further removal of glue for example on the cap strip is done with a file.
Step 8: Once all of the ribs are dry I then joined them up to profile sand. This takes quite some time to get the profile of the ribs together so they are the exact same size and profile
Step 9: All done and ready for placement onto the spars
It has been a few weeks and no posts, but that is largely because I am still doing the same thing. Glueing ribs. Whilst they are often a little different, it is the same process and the pics are identical. I have made two customisations on the lower inboard ribs.
On the butt rib I have made them half inch wide, not 1/4inch like the rest of the ribs and then on the rib outboard of that, I have sheeting the whole of the inboard side. This is all in order to strengthen the wing walk area on both wings. That way….people can walk over the top on a little more than egg shells.
Next post will be the last rib…given this morning I glued the second last rib. The end is in site. Unfortunately by Wing Kit is not.
It may appear that I haven’t been doing much. Whilst I have had a lot of travel for work and home…I have still be plugging away.
After completing the upper wing centre section, I have moved on to the Ribs for the wings. I was fortunate enough to find some complete, upper wing ribs, spare from a project around Cairns in Qld. Australia. They are in great condition and have never been used so that halved my workload! Onto building the wing ribs for the lower wing.
It took me a while to get the rib jigs sorted out. Turns out there are a couple of pages that had the included instructions that said to use the wrong jig number. Anyway, after some head scratching and swapping jigs, I found the right ones and got underway.
The process is pretty simple using the jigs. Layout some baking paper on the jig, load the mahogany ply cut out pieces that push out from the template…trim capstrip to size and glue!
I have a routine going that is largely a 48 hour cycle. Day one punch out pieces layout and cut capstrip. Morning of Day 2 – glue together. I can do a rib in about 40 minutes. Leave to dry 12 hours then break out of the jig. It is a little monotonous, but good watching the pile of finished ribs continue to grow.
I won’t post many of these photos as they are all the same!!