I have been doing pretty well about finally getting back out into the garage on a regular basis.  I haven't, however, been so good about updating my builders log...

I finally decided to tackle riveting of the flaps.  In Van's instructions it states that the flaps are the easiest control surface to assemble (I call bull_hit) on that but, I will elaborate below.  It mentions that no elaborate jigging is required, however, to assemble carefully because you can build in an unacceptable amount of twist.  The manual further stated that a stand may be helpful to hold the flaps while riveting.  After giving this some thought while sitting in my new Lazyboy airplane rocking chair, watching satellite TV, and surfing high speed internet, I decided that I pretty much had to build the "V" stand that Van's was referencing.  I was actively working while in the chair HONEST.  Sometimes you just have to stop and think of how you are going to proceed on the next task...

I needed this new chair for the plane project because I have already worn out one chair that just couldn't hold up to all the stresses associated with airplane building.  Either that or it was my big butt.

The trick I found here is to fabricate a "V" stand that will prevent introduction of twist into the flap.  Here's what I did:

1. I cut two pieces of fiberboard to the approximate size I needed.
2. Clamped the two boards together and clamped them to the bench overhanging it so that I could run a circular saw down them to cut out the "V".
3. Traced out the "V" using one of the flap ribs as a template.
4. Cut out the "V" with a circular saw and trimmed the notch up with a jig saw.  I clamps straight edges to the board so that I had a straight edge to run the circular saw guide against.  I wanted everything as straight as possible.
5. Took the side of the stand that would be mounted against the bench top and squared it off with a circular saw.  Now when the "V" stands were mounted to the bench top, they should both sit straight with respect to each other.
6. Mounted some 2x4's to the bench top and screwed the "V" stands to the 2x4's resting on top of the bench top surface.

This is what it ended up looking like.

After I completed the flaps, the decision to make the "V" stands was a necessity.  It would just be to hard to rivet the flaps without a good way to hold them in place.

I took Checkoway's route and mounted the "V" stands 40" apart.  That worked pretty well, although I don't think that it would be all that critical.

How am I going to get into the trailing edge and set those rivets????

Yep, it looks even smaller from the inside.

This was a bucking bar that I purchased a while back in anticipation of the flaps.  As it turned out, this bucking bar worked very well for the aft most rivet.  It was still hard to get into hold it.

Okay, if you look below, you can see two minor "bumps" in the skin. What had happened here is that I was setting the rivet on the opposite side (bottom skin) and left the clecos in the top skin. When the rivet hammer hit the rivet and the bucking bar, it banged against the skin.  What I had done previously and on all the other ribs was to take out several of the clecos so that the skin would move if it got hit by the bucking bar.  I was able to minimize the visibility of the two bumps by rubbing it with the rivet hammer (disconnected from the air line) and a mushroom set.  You have to be in just the right light to see this now.  It is nothing that a good paint job won't cover up...

I am a big fan of the Cherrymax rivets.  Man are they tough.  I used them to attach the rib to the front spar.  The trick here is that the top skin of the flap curls over the front spar.  I was not able to get my ground down blind rivet puller under the skin lip without lifting the lip slightly by hand.  Word of advice for anyone reading this>>> try to space out the force you apply to the skin.  If you just use the tip of your finger, you can put a bend in the skin.  To prevent this, I tried to roll the skin back using the side of my thumb so that the force was spread over a couple of inches.  And, you need to hold the skin while using your other hand to pull the blind rivet gun.

I didn't cut out any eyelets of the hinge to insert the hinge pins from the center.  However, I am seriously thinking of going back to do that.  I am going to think about that for a while before I change anything since the hinge is already riveted to the flaps.

About 8 hours of riveting and viola, I have a flap.  It is doable, however, it is not the simplest structure to put together.

I started assembly of the flap reinforcements to the various flap ribs and spars.  After I riveted the FL-706B-L plate and the FL-704-L rib together, something sure didn't look right.  I didn't notice anything when these two were clecoed together.  It looked like everything fit together as it should.  What appears to have happened here is that when I bent the plate for the 6.3 degrees (yeah right), I had set it on the bench and hit it with a "no bounce" hammer to tweak the fit up against the rib.  Well, that appeared to work, however, in reality, the way I was hitting the plate, must have given it a slight "curve".  When I riveted the plate to the rib, the curve of the plate was enough pull it away from the rib.  Well, I sure couldn't leave it like that.  You can see LIGHT between those two.  NOT GOOD.

What I ended up doing is drilling out all my AN470 rivets, placing the reinforcement plate in the bench vice between two sacrificial plates and squeezing the bejesus out of it.  I also had to place it in the vice in varying positions and trying to take the curve out by bending it by hand.  It is not easy to bend that by hand I tell ya...

When I was happy with the fit again, I clecoed it back together (and this time, I put the rivet factory head on the thinnest material. i.e.: the rib) and riveted the plate and the rib back together.  The second picture is a little blurry, but you can clearly see that there is no air gap between the rib and the plate.  MUCH BETTER...

I had better luck riveting these two together putting the factory head of the rivet on thinner material.

I then moved on to the flap spar and the FL706A angle reinforcement.  Again, I put the rivet factory head on the side of the thinnest material.  This turned out well with no problems.  Just make sure to leave the holes open where the rib is riveted to this assembly.

Next, I attached the flap ribs to the bottom skin.

After savoring the taste of success on completing my last fuel tank for this project, I began finishing up on other wing things I need to get done.
If you followed my previous flap entries, you know that I dimpled the top and the bottom of the flap spar.  Well, the BOTTOM is supposed to be countersunk so that you can rivet the flap hinge to it.  So today, I spent some time re-doing the flap spar.

So I didn't screw the spar up a second time, as soon as I got the orientation figured out, I Sharpie marked the bottom as "COUNTERSINK" and the top as "DIMPLE".  It worked, as I didn't make the dimple mistake twice.

Before I actually countersunk the flap spar, I drilled the flap hinge to the bottom spar.  To get alignment of the hinge on the spar, I measured 9/32" from the edge of the hinge and drew a line.  Then when clecoing the hinge to the spar, I just centered the line in the #40 holes in the spar.

I didn't get a lot of pictures of the rest of the days work because it was just deburring, dimpling, etc.  I was able to con Tami into coming out and helping me scrub the flap parts and wing skins with Alumiprep and Alodine.

Flap and pitot mast parts hanging after an alodine bath.

And the wing walk doubler...

And last, but not least, is the flap skins.

I got all the parts alodined and ready for a priming session tomorrow....  Not exciting progress, but it all has to get done before I can move onto something else.

I was pretty much terrible at taking photos on the right flap.  There were really no new challenges with the right flap over the left flap with one exception (self-induced).  I Sharpie mark all the holes after I drill them so that I know I drilled it to size.  I have had a couple of cases where I go to put dimple die in the hole and it doesn't fit.....  Ooops, missed match drilling the hole.

Just another shot.  Now for the self induced problem.  After drilling and deburring everything, I figured that I would dimple everything so that I would be ready to prime the flap parts.  I dimpled the flap spar, moved on and finished the rest of the flap parts.  While I was working on those "other flap parts", I realized I had made a big mistake.  I dimpled both the top and the bottom of the flap spar.  THAT IS A NO-NO.  The bottom holes of the flap spar are to be countersunk since this is where the flap hinge attaches.  New flap spar, $19.  That isn't too bad.  I should have just quit for the night before I started dimpling.  Just goes to show you that it is possible to screw up even a mindless task such as dimpling if you don't pay attention.

I don't have a lot to show for my weekend.  Friday, I went to renew my 3rd class medical.  WooHoo, I am good for another 2 years.  Saturday, Tami conned me in to do some shopping in Omaha.  WOW was that expensive.  Then there was Sunday....  I worked on finishing up odds and ends on the left flap.  For some reason, I was not super motivated today, so I didn't make giant leaps forward here.

I have been kind of dreading drilling the flap hinge.  I guess the last hinge I drilled (trim tab in the empennage), I wasn't all that happy how it turned out.  I ended up reviewing Dan C's experience with the flap hinge.  He had drilled the flap hinge to close (i.e.: the "eyes" of the hinge were placed to close to the flap spar and he barely made minimum edge distance on the hinge when drilling the wing side of the hinge.  I took his advice and marked the hinge made a line 9/32" from the edge of the hinge (measuring from the opposite side of the eyes).

The hinge is fairly flimsy until you get a few holes drilled and cleco's inserted.  I lined up the line I drew on the hinge and placed it in the center of the rear spar lower flange holes.  I used a few cleco clamps to hold everything in place while I drilled the #40 holes.

I am about half way through drilling the hinge.  It all lined up great.  When I got done with drilling the hinge, I left the hinge clecoed to the spar and then countersunk the spar lower holes to make room for the dimples on the lower skin.

The rest of my time today was spent drilling any remaining odds and ends I didn't get to yet, deburring what felt like 500 holes, and broke out the c-frame to dimple the flap skins.

I got everything on the left flap reading for priming and am going to wait until I have the right flap ready for priming and then do both flaps at the same time.  I almost showed ambition in that I broke out the parts for the right flap, but decided to call it an early night tonight. 

Tami and I are contemplating flying out to the Black Hills for the upcoming Labor Day weekend, so I spent some time looking at density altitude graphs for take-off and landings.  Flying into Sturgis, the elevation is around 3200' and this weekend is predicted to be cool, so I think the Cherokee ought to be able to handle their 5100' paved runway.  We'll see how this week at work goes....