Monthly Archives: April 2016

Flap Therapy


I’m looking for a new job.  The old one in Chicago just didn’t work out, so my employer and I have parted ways. For now, the majority of the project will stay in Illinois until I figure out where I’ll be working next. I did keep some parts to work on at my NY home, so at least I can make a little progress!

So, I got started on the flaps.  I figured that they would be pretty easy to build in my basement shop.

I made the brackets earlier.  They were pretty easy to make using my table saw and band saw.

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Like most sections, this one starts with lots of parts preparation.  There’s a little fluting to do on the nose ribs (made harder by the fact that my fluting pliers are still in Illinois) and some burnishing of gaps to prevent faceting, but the annoying part is cutting a bunch of tabs off the flap ribs.  They’re easy to identify (no problem with Left and Right parts) since the tab has no hole.   I cut these off using metal snips and then used a file to carefully trim the edge down.  The snips did cause the edge to bend a bit, so I had to carefully straighten them with some smooth nosed pliers.

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Similarly, each of these rounded cuts caused the ends to “pucker” out a little bit.  It’s not noticeable until you look carefully.  But as I applied the same smooth pliers to each, I could feel the pucker straighten out.  Then, there’s lots of deburring.  The edges and holes on all these ribs were a little rough.  Lots of hand work with sandpaper and files to get the edges prepped.   I don’t have pictures here of the hinge plates and doublers, but they too required a lot of hand work to smooth out cut marks.

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Then, you assemble the flap skeletons.  This is one of my favorite parts of building… when a “real” airplane part suddenly starts to emerge from the pile of small parts!

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Here’s a close up of the inboard and outboard rib assemblies.  At first, I though that the inboard one was for the inboard most position, and the outboard one was for the outboard most rib.  No….  They work together to hold a rod that will eventually connect to the flap control system.  A bit of squinting at the diagram made this all clear.

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The joggled hinge brackets line up very nicely.  There are holes in just one of the joggled parts.  Later, when everything is lined up, I’ll match drill and rivet them together.

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I’m working on both flaps at the same time to help make sure that I get the right parts in the right assembly!  The two are mirror images, so it helps to see both at the same time.

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Next, you cleco together the skeleton with the skins.  It takes a bit of finesse to get the nose skin in place.  It has to be fitted over the flap hinge brackets and then worked around the nose ribs.  Two of the nose rib holes are not pre-drilled.  We’ll get them in the next step.  I just kept working the clecos around the edge and eventually got the whole thing put together.

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I match drilled the “missing” holes in the nose ribs pretty quickly.  The only real problem I have is that I only have a small compressor at home.  The air drill quickly runs through all my air, so I have to wait occasionally for the compressor to catch up.

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You need to be careful drilling the trailing edge.  The instructions make it quite clear that you must drill perpendicular to the cord line not perpendicular to the edge.  It’s a 84 degree angle.  I used to have a block cut to that angle (from previous trailing edge work), but it is lost somewhere either in Illinois or in the scrap heap.  So, I just downloaded a paper protractor and taped it to a square.  This provided enough guidance to final drill without enlarging any of the holes.

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So, here’s two flaps!  Of course, now the real work begins.  I have to deburr, dimple, and prime all the parts (and match drill the hinge brackets) before putting this all back together.

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Lots of work upcoming.  The big one, of course, is to get a new job!  I have some leads and have done some interviews.  I’m hoping to hear soon what’s up with that.

I have enough parts to work on for the next month or so (flaps and ailerons) and may bring back the tanks when I go back out to Chicago to move out of my apartment.

I’m hoping the next couple weeks will bring some better direction.