§36-05 through -20 (Left), §36-21 thru -23 (both)

 It's been a very productive couple of days.   I built up the substructure of the Left flap, installed it into the forward/lower skin and verified that the upper/rear skin fit on both flaps.  I fully riveted the forward/lower skins on both of them.  

close up of typical cleco and rivets prior to pulling

overview of same state of construction

Dale came over and helped me bend the upper/rear skins.  The general portion of the KAI recommends using two boards that are hinged together to make a tool to bend the sheet metal into the final shape.   It didn't work worth a damn.  Bending the trailing edge all of the way to touch the other side did nothing; it simply sprang back to its original shape.   Following the advice of a VAF post, I ended up putting the flap skin on the floor, laying the board over it and literally walking on it back and forth and even springing up & down for good measure.   This produced about 75 % of the desired decrease in radius of curvature.   It was enough that it was not difficult to cleco together,  In fact, it was much easier than the leading edges of the ailerons, so I suspect that I'm in the correct ballpark.  I will enlist the opinions of other RV builders regarding the final shape of the trailing edges.

Last night I tackled the dreaded fuel sealant step and actually didn't make too much of a mess.  I had already riveted the forward/lower skin.  I scuffed the area that would get the fuel sealant.  I slide the upper/rear skin under the forward skin and fully clecoed it in place.  The natural spring in the sheet metal kept the rear edge away from the lip that got the sealant.   I smeared the sealant in place in about 12 minutes (out of a 30 min working time) and had a pretty easy time of clecoing the upper skin down onto the sealant.  I flipped it over, and clecoed/riveted the underside.  I was about half way through finishing all of the riveting (boring, but very satisfying) before having to close shop and go to work.

I'm expecting that I'll finish up both of them with another solid day in the shop.

RV-12 myth busted

 A few months ago I read a comment that you could tell your non-flying partner that in the event of pilot incapacitation, they could close the throttle and trim the plane full-up in order to achieve a controllable, low speed (and hopefully survivable) forced landing.

I had my doubts since the RV-12 has a very powerful stabilator and I can't recall ever getting close to full-up or full-down.  I took her up and tried it out.  Yep, it's not a good idea to put in full up trim. Even without power (prop wash over the stabilator), the plane was nearly in a trim stall with only 75 % trim.  I didn't push it any further and went home to continue building.

§ 34-14. Ailerons complete

Right now, it's about 3:00 on Saturday the 20th.  I'm pretty busy working on the plane and haven't bothered to update this for a while, so there's going to be a series of posts that cover the last few days. 

I finally finished the ailerons!   The replacement AN509-8R16s arrived.  I still can't remember what the new MS designation is, but the last two digits in that code do not match the AN suffixes.  In other words, I had several collections of the wrong size sitting around before the correct ones arrived.  I primed the lead because I have no idea how well the priming covered the inside of the steel tubes.  I realized that there was actually a fair amount of binding on the steel tube rather than the lead.  I used a #19 drill bit and re-drilled the factory holes and used a lot of 'English' (precessing the drill bit while drilling through the hole) and viola! -- the AN509's slipped in easily.  The left side went together w/o problem.  The right side was noticeably loose since I had chased the lock nuts so I used blue lactite to securely hold them in place.

The photo shows the completed ailerons.  In the foreground is the Right one and its uninstalled lead weights.  In the background is the completed Left one.  Note the fact that it is clearly nose heavy and has tilted forward since the center of mass is now in front of the center of rotation.

§36-05 thru -20 (R)

It's been a busy two days.  First, let's get the bad news out of the way.  (It has nothing to do with the plane, so, relax.) In order to be legally allowed to do my job I have to hold a set of "merit badges" such as BLS (CPR), ACLS, PALS, NRP and ATLS.  That last one, Advanced Trauma Life Support, is good for 4 years.  My current certificate expired on the 11th and I was informed that day that I was not allowed to work until I get it renewed.  I had received a warning, that I would be "locked out" of the schedule but I took that to mean that I could not be scheduled for any additional shifts.   I was never told that I had to stop working.   This has thrown a major monkey wrench into the ER's of two of my hospitals.  They are scrambling to find people to cover  4 shifts of 24 hrs each.  I've done what I can and will trade one shift to work at a hospital where I'm allowed a grace period to renew my ATLS.  Interestingly, I'm being told that the mandate is system wide, yet I'm allowed to work at Grady.  Go fig.   I renew on Saturday the 20th.

The good news is that I suddenly have an entire week off and I'm going to make good use of it!

As the title says, I got 16 pages done on the Right wing.  We're making progress.   Marking a page off in the book doesn't convey the prep work that goes into just assembling parts.   Most of yesterday morning & afternoon was spent clecoing all of the flap ribs onto the spars.  It went great, with only a few expected moments of head scratching ensuring that I was on track for L vs R.  Again, I would greatly appreciate Van's making explicit direction marks on their instructions and maybe a few comments to help orientation.  For example, on the flap spars a comment such as "The inboard side of the spar has two lightening holes between the 1st and 2nd rib.  The top webbing faces forward."     Anyway, after a false start or two I got both sets of ribs fully assembled. 

Ribs attached to the wrong spars

I looked at it and get ready to rivet.  Then I paused.  Then I pulled out the skins and laid them on the table and inserted the L rib subassembly into the L leading edge skin.  Everything slid together perfectly.  Happiness.  Just because I'm anal-retentive, I decided to cleco everything together so it would have some structural rigidity.  The ribs fit right in.  

Then I realized that the the holes in spar did not align with those of the skin.  I spent about an hour trying to figure out what had happened.  I never figured out how I spun myself into that circle of mistaken L vs R parts, but eventually I got both spars into both skins and then reattached everything.   The left flap (assembled w/ clecos) went onto the shelf and I went to work on the right.

Left flap assembly, correctly oriented

Last night I finished up deburring and fluting all of the ribs and hardware attach points.  Today, I tackled bucking the larger rivets that are what hold this plane together.  All in all, I think I did a pretty good job, but I'm nowhere near being consistent.  Oddly, I think that I may be holding the bucking bar too tightly.   The physics isn't completely clear to me but it might be that if I hold too tight then a lot of the impulse goes into moving my fingers against muscle force and that dissipates energy into my hand.  Maybe by letting the bar absorb all of the impulse, more energy is reflected back into the rivet to cause it to set.   I'll think about it later.

Typical driven rivets.  Factory head (on top) has a "smiley" 

which is only a cosmetic defect.

The 3 shop heads are acceptable. 

At least 80-90 % of them look pretty close to the text book pictures.  A few are ugly but serviceable.  One is clearly a basket case, but drilling it out will cause more damage to the flange and actually weaken the final joint so it stay.  In case you're curious, it stays hidden because this all internal stuff that will never be seen again after I close it up.

I'm taking a lunch break and plan to write more later tonight.

Intermission

I'm have a lot of trouble finishing the ailerons.  The last step is deceptively simple -- insert the lead weights and install screws to hold them in place.  Unfortunately, there is no way to apply back pressure to the nut plates in which the screws thread, and without back pressure it is very difficult to get the threads to engage.  I've ruined the AN509-8R16 screws that came with the kit. I ordered new ones from Aircraft Spruce, but they use the new designation and I ordered the wrong sizes.  (yes, sizes--plural.  I want some screws that are a tad larger than called out to try a few tricks.).  I'll document the issue in more detail when I get it finished.

As is typical for me, when I have a problem or am facing a "don't screw this up!" task, I often take a break and do something else for a while.  I find that it lets me ruminate on the problem and reduces the risk of doing something out of frustration and making it worse.  This weekend is one such example, hence the title of today's posting.

Remember back in June 2013 when I built a toolbox as a practice kit?  (No, you don't.   But you can go read Metal has been bent; Rivets have been placed for reference.)  That tool box and a second one have been accumulating miscellaneous small tools for 13 years.  Van's isn't selling that practice kit any more, but I got a different practice kit that's a lot more fun.

Light Box

Light Box in the dark

This is a very simple, straight forward aluminum box with Van's logo cut out from the front.  It's internally illuminated by a strip of LEDs.  The point of the kit is to learn how to work with aluminum sheet metal and rivets.   As mentioned in the 2013 post, I really didn't want to use driven rivets.  To be honest, I have been slightly afraid of driving rivets all this time.  I have a borrowed a rivet gun from a hangar neighbor and bought some accessories including a totally cool tungsten bucking bar.  (It's really fun to feel its heft as it's about 20 % denser than steel!)  I finally bucked rivets to build the box and it really wasn't a big deal after all.  I feel much better about the fact that I will be driving rivets to assemble the main wing spars in a month or so.

I also painted it. (duh!) I made it another learning opportunity by using two different brands of primer before painting.  I have a clear preference for one of them, so I'm glad I did it.

The second part of the intermission involves the tool boxes mentioned above.   When I started building this month, I just had a bunch of tools moved from the hangar and thrown into a new tool chest.  They really weren't organized and just kind of thrown in at random.  I quickly ran out of space and yesterday I bought a second tool chest.   

Before:

two tables full of loose tools

After:

Two organized tool chests

Now that the light box is finished and the tools are properly organized, I'm going back to building.  I'll start on the flaps while I wait for the AN509-8R16's to arrive so I can finish the ailerons (eventually.)

§34-12, -13

Well, that took longer than I thought.  (So, what else is new?)

Page 12 is deceptively simple -- cleco & rivet the leading & trailing edges to the framework of the ailerons.  

Having said that, it is a relatively time intensive process with some 700 rivets that need to be set. I was (and still am) somewhat paranoid about the whole L vs R thing and went to the trouble of clecoing together not one, but both of the ailerons.   The leading edges are under a great deal of tension so I did a 100 % cleco as my test fit.   Both sets of skins looked great, but it was a lot of time and effort.  All of that was done with the skins still in blue plastic, so it all had to come off so I could pull the plastic and deburr all the edges, then get clecoed back together again.   My wife offered to help and learned a little bit about clecoing.  (She's OK with flying in planes in order to get somewhere, but isn't into aviation as such. The reason she offered to help is because she loves me 💘.)   Lesson:  pull the plastic and deburr parts before test fitting things together.  If they fit, you can go straight to riveting instead of backtracking all of those clecos. 

 

My wife, learning how to cleco.

 I put them both together again and started riveting.  I  got the trailing edge skins attached and had riveted the upper surfaces of the leading edges when this caught my eye:

Poorly aligned parts

What you are looking at is the hole in the leading edge skin but only part of the hole in the counter weight underneath it.  It doesn't take an aeronautical engineer to figure out that something is wrong and there's no way I'm going to be able to fit a screw in there.   What happened was that I got fooled by the initial test fitting of the counterbalance tubes and stopped thinking about orientations.  After the test fit (see previous post) I took them off to give them one more coat of primer and must have swapped them when I re-attached them.  I didn't think to double check their alignment before doing all of that riveting.

Today  I drilled out ~ 130 LP4-3 rivets.  I only messed up 3 or 4 of the flanges of the underlying ribs and that pleasantly surprised me.   I swapped the balance tubes and crossed my fingers when I put the skins back on and they aligned perfectly.   Finishing up the riveting gave me two nearly finished ailerons.

Left Aileron

Left Aileron (inverted)

Right Aileron

Page 13 was pretty straightforward and I'm not bothering to put in a picture.  I tried installed the lead weights inside the counterweight tubes and it's going to be tricky.  See the next post.

§34-05 thru -09 Right, §34-10, §34-11

I built up the Right Aileron framework yesterday, but didn't get a chance to document it until tonight.  As hoped, it went together about twice as fast as the Left.  I'm getting back into the rhythm of building and it's really a good feeling.   I've often appreciated the fact that my memories of building the RV-12 are positive, even accounting for the days of frustration and setbacks.   I love flying, I love building, but I'm not real fond of maintaining.  Oh, well.   That's why I'm building again.

I'm still getting to know how to use the pneumatic squeezer.  There were a few rivets that felt 'off' and the part twisted in my hand when the rivet set.  On inspection, I found that there was a gap between the two pieces that were being joined and there was a bit of a bulge of rivet material in between them.  I looked at it for a few minutes before realizing that it wasn't "close enough" and drilled out a few rivets, bent the ribs back towards their desired shape and squeezed again.    Better.

Today I primed the steel balance tubes and proceeded to figure out how to countersink steel.  The countersink tool that I have is an offset handle that you can rotate by hand.   I gave that a try and realized very quickly that I was "Going nowhere mighty fast".  (Scotty, Star Trek TOS).   It took about 30 min of prowling around my converted garage (aka "the shop") before I stumbled upon a solution.  The deburring tool had come with a 12" extension that I never used.  I cut off the end that accepted the counter sink tool and stuck that in the chuck of my hand drill and solved the problem. 

There are several comments in VAF regarding ensuring that the counterweight tubes are properly oriented.  I can't find any difference between them and they appear perfectly symmetrical.  Having said that, I was paranoid that I would mess something up so I decided to completely cleco the LE and TE skins to both ailerons before doing anything permanent. In the process I developed a migraine worth of confusion because the TE skins simply did not align.   I double checked my part numbers (e.g., the suffixes -001 and -002) but everything was correct, except that they didn't fit.  I eventually concluded that I had swapped the identity of the R and L parts in my mind and was actually assembling the wrong parts.   I swapped and everything fit together in typical Van's fashion.

Screwing in the bolts that hold the counterweights on was a challenge.   I truly wish that Mr Phillips had not made such an impression on the manufacturing industry.   Should I ever be asked to select fasteners, I will NEVER select a Phillips head screw.  They require significant axial loading in order to prevent the screw from stripping.  Hex, Robertson (square), Torx -- you name it -- any other screw design (well, not slotted) is better.

OK.  Enough bitching.  Next session will be a lot of preparation of the leading & trailing edges, then clecoeing everything together, then riveting.   That'll be a nice bit of progress!

Completed R frame, 

temporary LE skins, 

attached counterweights

 and trimmed tails.