May 26th, 2012

This week I put the left flap together. Because all the parts had already been prepped (the way Van has you do it you work through both left and right completely before riveting anything) the left flap went pretty quickly.

 Riveted the nose rib assemblies together.

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Riveted the two smaller nose rib assemblies to the spar.

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Then riveted the inboard nose rib assembly, FL906A,B,and C (bracket,spacer and plate) to the spar and the inboard FL905 rib.

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Once all those are riveted the remaining FL905 ribs are riveted to the flap spar.

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Inside view of a rib riveted to the flap spar. This is the left flap.

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Clecoed the top skin to the ribs, then clecoed the FL901A and FL901B nose skins to the ribs and spar.

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Drilled the inboard nose ribs to 7/64" and riveted with MK319BS pulled rivets (the inboard nose ribs are enclosed by the skin so there is no way to get inside to buck them).

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Once the nose ribs were done you put the flap assembly in the cradle (spar, nose skins, top skins and ribs, but minus the bottom skin and trailing edge). The top skin and nose skin are then flush riveted to the spar.

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This is what it looks like once the top side of the nose skins and top skin is riveted to the flap spar.

Note the wave in the trailing edge in the picture below.  This is the reason it's piled with so much weight when riveting.  The weight straightens everything out so you don't get curled trailing edges.

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Once that is finished, the assembly is laid on the table and the bottom skin is clecoed into place under the nose skin, then the entire assembly is weighted down. Then the bottom side of the nose skin as well as the bottom skin is riveted to the spar with flush rivets.

Photo album of all the aileron and flap photos to date.

This is a link to the entire batch of photos of the flaps and ailerons. A lot are labelled but not all.

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May 20th, 2012

Kind of behind in posting (this is actually being posted Monday the 21st after just finishing up the right flap). Glad to have that behind me.

I've read a bunch of posts by folks that had it come out less than straight and I really really really didn't want to do that. Very happy with how it came out.

The normal sequence of events (this applies to pretty much the entire airplane) is fabricate any required parts, cleco them all together, do all the match drilling, then take everything apart, deburr any remaining rough edges and all drilled holes, then machine countersink and dimple appropriately.  Once you've done all that, then you put it back together and rivet.

First you rivet the nose ribs and hinge brackets together.  There are two nose ribs back to back, with two hinge brackets and a thick spacer  in between.  All 5 pieces get riveted together as a unit, then are riveted to the spar.

Nose rib/flap bracket assembly.

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Once all the nose ribs/brackets are put together, they get riveted to the flap spar.

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Once the nose ribs and bracket assemblies were in place you rivet on the FL-905 flap ribs.


The thick plate on the end is FL-906B plate. The flap actuator mechanism connects to this plate to move the flaps. The area is reinforced with the FL-906A angle and the rib, spar and nose ribs are riveted together.  If you look at the ribs you'll notice none of the holes are dimpled.  I somehow missed that when I was going through my checklist prior to riveting.



Of course I noticed this *after* I'd riveted the nose rib/hinge assembly and the main ribs into place.  So I had about a 6 foot long structure with some very tight holes, all of which had to be dimpled.

Thank goodness for the tight spot dimple tool I got from Cleaveland Tools.  I hung this dude way off the table corner at a 45 degree angle and was able to work it in to all the tight spots and get the dimples in place.  Whew.

Tight spot dimple tool is below.  Basically the socket on the end is where the dimple ends up - you use the other side of a dimple die on top with the sheet metal sandwiched in between.



Once everything was dimpled it was time to attach the FL-901A and FL-901B nose skins. These are a very tight fit. The best way I found to do it was weight the flap as suggested by Van (used about 50# of sand in large freezer bags) and then use duct tape to hold the skin while I progressively tightened it. After two or three rounds of working it tighter I could get a cleco in one end. After that I just worked progressively along until the whole thing was clecoed in place.



The inboard ribs are inaccessible and have to be riveted with MK-319BS flush pulled rivets. The only ribs that can use AN426 rivets are the most outboard.



This is what the center section looks like where FL-901A and FL-901B inboard and outboard nose skins meet in the middle.



Riveting the FL-901C top skin to the nose skins and the FL-903 flap spar.



Working along the spar riveting the FL-901C top skin to the nose skins and FL-903 spar. The FL-905 ribs (vertical row of rivets) are not riveted until later.



Top skin is fully riveted and has also been riveted to the FL-905 ribs. I forgot to take a picture of the bottom skin being riveted in place. Basically the bottom skin is put in place, the whole thing is weighted to the table and you reach inside and flush rivet the bottom skin to the nose skins and spar. Tight quarters. Once that is done the AEX trailing edge wedge is put in place and everything is clecoed together.



Other side of the same assembly.  At this point the rib holes are drilled oversize to accept the MK-319BS pulled rivets since there is no way to reach inside and flush rivet the bottom skin to the ribs.



Flap assembly after flipping upside down, drilling the rib rivet holes oversize, then riveting everything in place.  Next step is to put rivets in the trailing edge, weight it all down, then back rivet the trailing edge into place.



I didn't take a picture during the back riveting. I'll try to remember to do that when I do the other flap. Finished right flap below.



Thankfully the trailing edge came out nice and straight.







Next - on to the left flap....

May 6th, 2012

Working on the left flap this week. There are lots of dire warnings (even more than there were for the ailerons) regarding building these dudes dead flat. As big as they are spanwise, a bit of washout could make for some interesting handling. The plans call for making a dead flat table about 8 feet long (already had that from the empennage). The difference here is that you need to make a flat top that can be drilled to allow clecoes to poke through. I got a sheet of 3/4" MDF, ripped it down the middle, and raised it with some dead straight 2x4's so there was enough clearance in the middle.

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You lay the flap down, match drill every other skin hole to the table, then take it off and drill the holes out to 5/8".

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Here's what it looks like when the holes are mostly drilled:

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Once we get that done, we match add the ribs, match drill to spar and bottom skins, cleco, then stick the assembly onto the table. The clecoes on the underside of the skin fit into the previously drilled holes so it lays dead flat.

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