Flapping my Wings…

1/29/2018 – Right Wing Flap Construction – 4.5 hours

Here are the parts before beginning.  KW drilled the lower holes on the spar the flange, as well as the lightening holes and rib mounting holes.

Here are the spar and ribs set in place on the lower skin.  Note the upward fold at the rear of the lower skin.  I will be referring to this as the rear spar area.  The main spar is held in place with c-clamps.

A closeup view of rear spar area on the flap.  It has to be trimmed on both sides.  Here, I am drilling the relief hole to trim the 1 3/4″ off the inboard side.  The cuts are then made to the relief hole, and there is much less stress concentration on the finished part.

Once the rear spar are has been trimmed to length, all the ribs can be clamped into position.  The rib holes through the main spar are then transferred through the ribs, and these are clecoed into place.

Now the rib tails are drilled and clecoed to the rear spar extension.  The structure is starting to take shape, but it is very floppy at this stage.  The skin will lock it in position.

After the structure is set, the skin holes on the spar flange are match drilled through the skin.  The extra long drill bit is a big help here.

The positions of the ribs are drawn on the outside of the bottom skin, and skin holes are drilled into the skin and lower rib flanges.  Lots of clecos needed.  Did I mention that I love rivet fans?

Here you can see all the lower holes drilled through the skin into the ribs and spar.

Now the top skin is clamped into position.  Note that this wraps around the back of the spar and forms the trailing edge.

Not shown, I drilled the rear holes on each rib through the bottom skin, locking the skin in position on the flap.

Drawing the position of the spar flange onto the outside of the top skin.

Now, the top skin is drilled to the top spar flange.  At this point, the flap must be perfectly flat, because this is the point where it stops feeling like a dishrag, and starts feeling like a solid flap.  Notice that I still have not drilled the end of the inboard flap rib.  This area must be match drilled with the actuator hardware.

Apparently, I stopped tacking pictures at this point – but there isn’t much else that I did today except to draw the positions of the ribs on the top, and drill the rivet pattern into the top skin.  I am very impressed with the simplicity and solidity of the flap.

*All* I have left to do on the flap is to drill the skin to the top rivet flanges, drill the joint between the top and bottom skins on the bottom of the flap,  find and build the flap mounting hardware, drill the flap hinge, and then dissasemble, debur, dimple, countersink the hinge, zinc chromate the parts, and then rivet it all together again.  And then I have to build the second flap.

Happy with today’s progress.  Having a lot of fun, and hope it stays this way.  I think the secret is to build each part as a separate project – not to think of it as building an airplane, but as building airplane parts.  That way, there are many small completions.


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