More Flap Work

Time: 8 Hours

I started today with a few errands I needed to finish before heading out into the Hangar. When I got back a set out to match drill all the holes in the right flap skins and the hinge like I did on the left flap. That went pretty fast since I had just did the left side. Before I broke down all the parts I decided to jump ahead a couple of steps and fabricate the flap support plate and angle. These two pieces beef up the inboard rib/spar area where the flap control arm will connect. First you need to cut down a couple of angles from a piece of 1.5″ x 2″ stock.

I then cut down the shorter edge to 3/4″ per the plans.

The inboard rib angles towards the inboard as it goes aft which means the plate must be bent to match so that the end that rivets to the angle I just made is square. Vans says that the angle is to be 6.3° First I clamped the piece in my bench top vise at the prescribed 25/32″ line.

I then used my digital level to establish 0°. You can see that it wasn’t perfectly 90° in the vise, probably my bench is off a little. I then zeroed it out to establish my starting point. I then clamped two boards on both sides of the plate and made a sandwich to give me some leverage and bent away. After a couple of try’s I got the angle perfect.



The end result leaves the angle square with the spar and the plate matched to the inboard rib.

I then fabricated the 4 spacers needed on the aft tips of the inboard and outboard ribs. These are needed where the bottom flap skin stops short of the aft end if the rib and the top skin wraps around and overlaps the bottoms skin.

The bottom skin curls up at the aft end to essentially create the rear spar of the flap. The aft end of the 4 inner ribs get a single rivet to attach to this rear spar. Van’s says that sometimes the rib does not touch the rear spar and you need to add spacers. I had to make 4 of them for the right flap out if .020 sheet but I didn’t need any on the left flap, go figure.

I then I larger the forward most hole in the support plate to 1/4″ and drilled the 2 holes for the platenut. This is where the flap push rod will connect.

I then put the assembled right flap on the shelf and took the left flap completely apart for deburring and edge finishing. The first thing I did was to drill the spar holes to my workbench to allow for countersinking of the bottom flange of the spar. The top flange can be dimpled but the bottom flange has the hinge on it so you want the inside edge of the spar flange flat so that the hinge sits flush. You don’t want to dimple or countersink the hinge flanges as they are too soft.

I did a little edge finishing before deciding that 8 hours was enough for today and my back is getting a little sore. I will get another good weekend worth of work over the next 2 days.

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