Day 33 - Covering!      Hours today: 36      Hours so far: 324


Covering! It seems like a long time coming. 36 hours, and I have covered everything except for the wings and fuselage. That is, first stage covering. I still have the polybrush, tapes, and gussets to do. I am not going to explain the process of covering - the build manual has a lot of good tips, but I highly recommend the manual by the Polyfiber people. Despite the fact that everything they sell is really expensive, the manual is well worth it. This day will describe covering an elevator, according to Rob - who is definitely no expert, so please take further advice!

Click on the pictures to enlarge.

Clean the piece you are going to cover - no pen marks, no dirt, nothing. Then decide how you are going to cover it - one piece or two? Then lay the fabric on and cut holes for any protrusions. Then use masking tape for glue lines (see manual). When applying glue, brush it on once, then do not over-brush it - you will get lumps. Put 4 layers of glue on, then offer up the fabric. With the elevator I chose to do it in two pieces, and I used one of the straight edges for the first glued edge. This picture shows the bottom of the elevator being covered first, so wrap the bottom skin around the elevator tubing. Apply a little MEK to activate the glue, then rub your finger along the glue line to get the glue into the fabric - MEK is carcinogenic, use gloves!

With the first (trailing) edge glued in place, glue the second (leading) edge. Don't pull the fabric tight, but try to make sure the glue line has no wrinkles in it. The sagginess of the fabric is taken up with heat-shrinking, and even glue lumps (inevitable) or other wrinkles can be rolled out with an iron, but try to avoid lumps (no over-brushing) or wrinkles in the first place!

Hmm... curves. Give yourself a bit of fabric overlap to pull on, don't try to cut the fabric before you have the curve. Iron the fabric near the curve to shrink it, then pull the fabric into place and iron at the same time - roll the iron around the tubing, try to tease it into the right shape. It's a technique which sounds difficult but is actually fairly easy to get the hang of. Then apply MEK and rub your finger again to get the fabric to stick.

That's the first side covered. Use a new and sharp razor blade - not a regular knife - to trim. It avoids fraying and gives clean cut lines. I have found that a razor blade lasts for about one elevator at most. So far I have used around 10 blades, I bet I use another 10 or 15 before I'm done, the fabric blunts the blades really quickly. Getting a straight cut line is tricky - even if you have carefully painted a straight glue edge and the razor is sharp. This is why you cover the underside first, so that all rough cut lines eventually end up on the underside!

The topside is a repeat of the underside. Again use masking tape for clean glue lines, if possible use one of the fabric straight edges to start. This picture shows the topside finished and glued in place, and the excess needs trimming. I have not found a satisfactory way of getting a beautifully clean cut line, despite trying with steel rulers, tape, pencil lines... ah well!

The 'finished' job. I have so far ironed to 250 fahrenheit, getting rid of wrinkles, lumps and other imperfections from the glue lines and the fabric. Next I will heat the fabric to 350 before starting on the polybrush and tapes.

It's not as tricky as I imagined. I did do the trim flap 5 times for practice, and I feel that the last elevator I did was way better than the first gear leg - if you want a good job then practice like crazy! Some stuff can be done in one piece (such as a flap) but others need two pieces. Plan ahead, cut out all the holes for protrusions first, glue carefully and take your time. Each flap or aileron took me about 4 hours... Next page