Rear channels and flapperon arms

Back in the shop today, getting more done on the right wing.

I started the day by deciding what i wanted to do next.  The inboard rear channel doubler needs to be riveted to the channel.  To do this, I first needed to drill the aft rib flanges out to A5.  I could get the top two holes done, but the rear channel needed to be lifted to get the bottom ones because the table was in the way of keeping the drill straight.

Unlike the lower holes of the nose ribs at the spar, I made the room by removing the ribs from the spar but leaving them attached to the rear channel. I moved everything back to the edge of the table:

With all the holes in the rear channel upsized to A5 where necessary, I took the ribs off to drill the pilot holes for the lower skins to A3 on the inboard and outboard rear channels:

All holes are deburred and the parts for the rear channel are rubbed down with ScotchBrite.....

.....cleaned then primed:

To keep things straight for re-assembly with clecos, I finger clamped the rear channel to the top of the main spar:

It might seem I'm overdoing it with clecos but this is by design.  Not only does this keep everything tight, but by adding a cleco in every hole I don't want to rivet yet, it prevents me from accidently doing just that and further not having to drill a perfectly good rivet out (a lesson I've learned already).  The top of the doubler will be pilot holes for the top wing skin and top of the trailing edge skin, so I won't be riveting those yet.  Same with the holes for the main ribs.

Same goes with the inboard rear channel doubler plate.  I can't rivet it yet until I fit the first main rib (remember it tucks between the rear channel and the doubler plate).  As a reminder, I filled those affected holes with clecos:

I decided it was better the lie the rear channel flat on the table to do the rivets on the doubler.  Same process as every other long line of rivets - alternating holes, rivet between the clecos, then remove the clecos and finish the rest:

The centre channel doubler will be clecoed and riveted when I add the rear strut pickup.  That will happen when the spar and wing skeleton get elevated up on square tubing.  That will allow the flapperon brackets to be added as well.

With the rear channels complete and awaiting final assembly to the main ribs and wing skins, it was time to tackle the flapperon arms.  First up was drilling the tip of the first one to A3 size.  I didn't get a picture of the other three, but I did the same thing as the slat attach brackets for the nose ribs.  Start with the first one, stack the rest together with a clamp and use the first as a pilot hole for the other three.

Using the same idea as the slat brackets, I laid out a work space.  The plans call for the pilot hole to be 48mm below the lateral line of the wing rib back from the spar, and 894mm rearward from the spar.

To accomplish this, I laid the rib out on some boards and used a block (the purple one in the picture) as my "spar".  With the rib in position, I traced it out on the board with a marker:

The crosshairs marked and A3 hole drilled on the lower board below represents where the pilot hole of the flapperon arm is positioned relative to the wing ribs as per the measurements described above:

A cleco holds the flapperon arm in position via the A3 pilot hole:

​Pivoting the flapperon arm upwards and under the rib until the top edge of the arm meets the top of the rib flange as shown in the plans:

Remove the rib and the flapperon arm is in the exact position it needs to be:

Extending the lines of the flapperon arm "head" with marker lines makes it easy to reposition if necessary.....

....and allows me to visualize where the flapperon arm is relative to the rib when laying out the rivet pattern for attaching them together,  This saves having to flip everything over and drilling from the arm side.  A3 pilot holes are first drilled through the rib using the layout shown in the plans:

With the A3 pilot holes drilled, the arm is added back again, lined up and the pilot holes are drilled through the arm and clecoed to the board to keep everything straight and correct:

All holes, except the lower 4 are brought up to final A5 size:

The whole assembly if flipped over and a "L" bracket is added to support the lower wing skin at the rib/arm joint.  The L is back-drilled suing the A3 holes then upsized to A5:

The skin support L in position on the flapperon arm:

The arm seems to stick out a long way to the rear from the rib, but it's deceiving to look at - the trailing edge skin still needs to be added to the aft of the rear wing channel.  This will close the gap between the wing and flapperons substantially.

A good productive day.  Next up will be the other three flapperon arms.  With those complete, I can raise everything up on steel beams on the bench and start prepping the wing skins.

Even the little steps are getting me closer.  Thanks for following along.