Good progress since the last blog entry. I finished up the second outboard flap and started on the last inboard one.
The skin is bent correctly and the rivet lines are laid out:
With the skin riveted in place, the nose skin is rounded over. Lengths of wood under the ratchet straps draw the skin down tight:
With the skin in place over the spar, rivet holes are drilled, alternating out from the middle of the spar to the ends - this helps fasten the skin evenly and avoid twisting.
With all holes now drilled, it all comes apart (AGAIN) for final debur, cleanup and priming:
The spar is primed on top and bottom flanges, the web in those places where ribs attach:
The skin is also cleaned, debur and primed:
I'm pleased with my attention to measuring detail. Rivet holes are perfectly centred in the nose rib and the flap pickup angle is cleanly passing through the skin:
All buttoned up awaiting final rivets before heading to storage and later inspection:
Outboard flap splice plate, drilled and primed, ready to be riveted to the inboard rib:
Final rivets complete on the underside and flap splice plate added. Lined up on the bench with it's opposite wing mate. Really pleased how these outboard flaps turned out.
So here is an updated "completion" diagram. 3 of 4 flaps complete!
Onto the second inboard (and last) flap. To fold the trailing edge, Ron helped me clamp it down using a long board. A 1/8th inch spaced inside prevents the trailing edge from getting crushed. The secret here is gently tightening each clamp in turn so the trailing edge remains straight and true. The square steel pipe helps keep everything down even
It didn't squeeze it down quite enough, but close enough to be drawn down flat to the ribs:
You may recall from an earlier post (see here) that it took a while to figure out the correct toe-in angle at the root of the inboard flap. In order to keep them the same and allow for any slight deviation from the plans, it's best to copy the first one I made. To do this, I used an adjustable angle protractor, measuring the trailing edge and transferring it to the skin of the second one:
After measuring again I laid out the rivet lines on both the top and bottom of the flap. The root and tip ribs already had holes in them from a previous attempt to skin it, but that first attempt led to a bad twist in the finished flap (long sad story). Rather than make a entirely new rib, I used the duplicator to match the new skin holes. With a couple on each end done, I took the skeleton back out and pre-drilled the skin rivet holes out to A3:
With the spar in place and square to the skin, I drilled through the skin and into the ribs, using the red centre lines on the rib to keep them square. Working up from the trailing edge and out from the middle keeps the skin nice and flat and straight, the weight of the square steel tube helps immensely - much better this time!
Next up, I'll flip everything over and begin the process of riveting the bottom skin to the ribs and begin bending the nose skin over to meet the spar, including laying out the flap angle pass-through holes.
One more full day in the shop this week should finish off the flap assemblies.
Thanks for reading, soon I'll have something new to show you besides flaps!!
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Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.