This weekend I took on step #1 from the manual, make the skins for all the foam parts. I gotta say this is one of the more mind numbing and labor intensive parts of the build. There is a technique you need to follow to get good results. The quality of this work will eventually play out in the covering so its best not to cut corners.
The sheeting in the kit comes “edge trued”. This means that the long edges of each sheet should be a mathematically perfect straight line. The lines don’t have to be parallel, just straight. As it was I found that just about every sheet in the kit had was slightly bulged in the middle. Sometimes its ok to just bend the sheet and hold it in place with masking tape. Most of the time you should sand the edge to make it straighter. I say should because you don’t have to, you could just fill the gap with glue. Of course I’m some sort of perfectionist so I had to go and true the edges myself.
Walt(ref) has a fancy rig(ref) to true his sheeting. I didn’t have one so I improvised. The edge of the door that tops my workbench is very straight. I just moved the sheet to the edge and held it down with my large ruler. Then I took a 12″ T-Bar sander and sanded it square against the door. You wont have to take off much, the sheets are already 90% there.
I used a gram scale to weight all the pieces and split them up into piles of lite, medium and heavy. On the flight surfaces I put the heavy wood over the wing tube area and the light wood towards the front and back of the panel. On the other panels the wood has already been sorted and cut so you don’t really have any decisions to make about how to use the wood.
Once you trial fit the sheets and don’t see any big gaps its time to tape the seams together with 3/4″ masking tape. Here is the first bit of technique: rub the tape in hard so glue can’t get under it. On the first wing skin I didn’t press hard enough and got a lot of extra glue under the tape. the rest of them I really got it stuck down and the glue cant go anywhere. Once the skin is taped together its time to glue the seams. What worked best for me was to work 3 seams at a time. Apply the glue, remove the excess and then tape across all three seams. This makes for faster work and fewer pesky bits of tape to remove when its all done.
To apply the glue you are going to need some sort of syringe type device with a fine tip. I went to the local Walgreens and asked the pharmacist if they had any syringes and got a freebie! It came without a tip thought so I had to make something up. I cut the end off a dropper that I had for applying CA, I get them at my LHS. If you cant find these then the CA tips available at Hobby-Lobby on online may also work. Either way plan on having this tool before you get started. Even blunt tipped syringes cant be had at a drug store in the USA.
Once each panel is complete I found that it wanted to curl up due to the tension in the tape. Just flip it back over so the side with the seams taped is on top. I used books to hold the panel flat as it dried. I knew I would need that calculus book for something! I left each panel under the weight for about an hour. They come out very flat and uniform, much more so that some pics I have seen of other builds online, so I think I’m on the right track. I did some of the smaller skins first to get the hang of it and they went pretty well. I was using an old credit card to scrape off the glue and I didn’t realize that it had some bumps on it. This put some long scratches in the skins. I switched to a different tool, a soft silicone spatula, for removing the excess glue and this worked much better.
I had a couple of screw ups this week. The instructions show the rudder and fin (v-stab) coming out of some 48″ planks with some scrap on the end. the instructions even list these planks on the materials list. Last week I used some of the “scrap” off the end of a 48″ plank as end caps for the wing tube sockets. Turns out that the only 48″ planks packed in this kit are for the wings. The other bits come pre cut in bundles and that “scrap” isn’t in the kit. Luckily i didnt cut very much off the end so I was able to use the piece for the leading edge of two of the wing panels, cut diagonally.
I also managed to screw up the first wing panel by forgetting to include on of the planks. Not a difficult mistake to correct though. I just split on of the planks and inserted the missing piece. You would have to know it was done wrong to spot the mistake.
I still have a few more skins to do this week. I’m going to get them all done now because this part of the build is boring.