Drilling Holes for Fabric Rivets on Wing Bottom

We decided to use fabric rivets instead of rib stitching on the wings.  To make drilling the holes easier, Ed welded up a drilling guide for the rib cap strip holes.  All we had to do is measure where we wanted the hole to be drilled and the guide allowed for a quick, precisely located hole to be drilled.  We played around a lot with hole spacing on the wing bottom.  When one hole was okay, another would be located in an undesirable location.  We finally settled on starting 1" along the rib cap strip from the front of the wing and the hole spacing was 2.75".  This allowed no holes to be drilled on or near the drag tubes and wing spars.  All holes were drilled in the bottom of the left wing.  Hours: 3

Ed drilling fabric rivet hole using drill guide

Fuel Tank Blocks and Fitting Trimming

Today we got two things done around the fuel tank.  First, five wood blocks were added between Rib#1 and the fuel tank.  These are added to prevent the rib from bowing inward during the fabric shrinking process.  Three blocks were added to the bottom area and two blocks were added to the top area.

Three blocks on the bottom

Two blocks on the top

The rib also needed to be trimmed to allow access to the fuel access hole in the fuel tank.  A Dremel with sanding bit made easy work of this. Tape was temporarily applied over the hole to keep foreign objects out of the tank. Hours: 2.5

Rib trimmed for fuel fitting

Attaching more fabric attachment plates

Today we attached two fabric attachment plates that go over the rear lift-strut attach brackets.  There are already two holes drilled in the bracket, and we had to precisely match the holes in the fabric plates to the brackets.  To do this, a hole on one side of the fabric plate was fastened in place temporarily with a cleco.  We then used our newly created strap-locator tool to locate and drill the second hole to guarantee that it lined up with the pre-existing holes in bracket.  We repeated this process for the second fabric plate on the other lift-strut bracket.  We then cleaned, epoxied and riveted the two fabric attachment plates on the left wing.  The picture shows Michael riveting one of the plates after epoxy was applied.  Hours: 1.5

Michael riveting on a fabric attachment plate

Fabric plates for rear lift strut attach points

Michael constructed another fabric plate for the rear lift strut attach bracket.  We've been primarily working on the left wing, but this is a part that will be used (eventually) on the right wing.

While Michael was working on this, I welded up a small tool that will help us align and drill holes in the fabric plates.  It's basically a strap-duplicator (hole-finder) that has a small nub on the bottom strap that will drop into an existing hole, and a thicker plate on the top strap with a 1/8" hole (for a drill bit) that is precisely aligned with the nub.  This allows us to precisely locate and drill holes in the fabric plate that lines up with existing holes in the strut attach brackets.  The two straps were made from an old band-saw blade that was in our recycle pile.  Nice to be able to find a new use for these old parts.  Hours: 2.5

Strap duplicator (hole finder)

Rear Lift Strut Fabric Plates

A fabric plate for the wing rear lift strut attach bracket was constructed out of the 4"x6" material provided with the kit. The parts had to be modified from the supplied template to clear the bracket. Hours: 1

Rear Lift Strut Bracket Fabric Plate and Template

Front Lift Strut Fabric Plates

Two fabric plates for the wings front lift strut attach brackets were constructed out of the 4"x6" material provided with the kit. The parts had to be slightly modified from the supplied template to clear the bracket. Hours: 1

Two Fabric Plates and Corresponding Template

Flap and Aileron Fabric Plates Installed

The two aileron and one flap pulley fabric mounting plates were drilled and deburred.  The plates were dimpled for flush mounted rivets and the mating surface was either dimpled or countersunk to match the plates.  All the parts were then removed and the mating surfaces were sanded with 220 grit sandpaper and then cleaned with acetone.  Hysol epoxy was spread on the mating areas and the plates were riveted into place with the appropriate flush mount rivets.  After the epoxy was given some time to set up, the excess epoxy was either removed or filleted.  Hours: 2

Ed applying Epoxy for one of the fabric plate installations

Flap pulley fabric plate installed

Aileron top pulley fabric plate installed

Aileron bottom pulley fabric plate installed

Aileron and Flap Pulley Fabric Plates

The fabric plates for the aileron and flap pulleys were finished off.  This required taking the unmodified fabric plates that were constructed earlier and cutting custom slots to fit around the exposed pulleys.  Once they were completed they were clamped into position to be drilled at a later time.  Hours: 1

Aileron Pulley Bracket

After a few days away from working on the airplane we finally got back to installing the aileron pulley brackets.  We double and triple checked the location of the "top" bracket to make sure of its alignment.  Once we were satisfied we drilled the four mounting holes and cleco'd as we went.  Both pulley bracket holes were deburred before we cleaned the spar and brackets with sandpaper and acetone.  Hysol epoxy was put on the bottom side of the bracket and each was riveted in place with a total of eight CCP-44 rivets.  After 30 minutes of setup time, the excess epoxy was smoothed to create nice fillets.  Hours: 1

Aileron pulley brackets installed