§ 28 -6 thru 13 -- push rods

 Van's is famous for the smoothness of the control feel of their airplanes.  I think one of the contributing factors is that they use bearings and pushrods whenever possible when designing their flight control linkages.  I had already assembled the rotational bearings in bell cranks.  This post documents building the push rods that attach to them.

I also like a really nice technique they employed for establishing the exact length of the push rods.  When you build one, you can turn the stem of the spherical bearing to move the length in or out by 1/48" at a time.  When I built the RV-12, I remember trying to very precise about my measurement.  In the RV-15, they have you assemble the push rod and then use temporary bolts to insert into holes provided in the main spar.  In other words, the main spar has a jig built in to it.   Very easy to twist the bearings to get a perfect fit -- no tape measure required!

I used blue locktite as a safety feature for the jam nuts and ruined one of the spherical bearings when the locktite dripped on the bearing itself.  Although it felt like it was still moving freely in its race, I expect that it will not remain in good condition for very long.  I tossed it in the junk bucket and ordered another one ($26!) from Van's.

Aileron Push Rods

Push rods, prior to riveting and installation of bearings

I started the final assembly of this chapter where the bellcranks get installed in the mixer and the pushrods get attached to the bellcranks.   Even without the skins on the wing, it's definitely challenging!   I'd like to have a trained capuchin monkey w/ tiny hands to help out.    I am absolutely dreading / afraid of trying to install the flap control mechanism after the wing is closed up!

§27 L; IB Mixer - Rear Spar

 This was also a pretty straightforward chapter.  The Inboard Mixer was nestled into the space just next to the tank and directly in front of the spar attachment area.  The holes that were left open for the rear spar attachment were then used to rivet the mixer to the spar.  Here's where the infamous Cherry Max Rivets got used -- all 39 of them.  These are pull rivets ("pop rivets", although that's actually another brand name) but they are stronger than the typical LP3-4's used nearly everywhere else in the plane.   The book says to be sure to pull exactly in line with the stem, but that's not possible with a few of the rivets because there is a flange immediately in the way.  I bent the flanges as much as I could and did the best job possible.

IB Mixer, as viewed from the front of the wing assembly

For some reason, they decided to have the flap tracks installed in this chapter rather than give them their own chapter.   The flap tracks are interesting; they are jet black and I'm not sure if they're aluminum or something else.  I am getting better at riveting.  There were two rivets that couldn't be bucked with my titanium bar.  I used a flat plate of steel and got creative.  Worked great!

 

Flap Tracks

§26 L; Rear Spar - Tank

 I got a lot accomplished in the last week, but one thing I didn't have time to do was document it.  I typically have slow times between patients at night, but not recently.  Sorry for the delay.   I'll publish several updates in a row so i don't overwhelm you with a really long post.

Attaching the rear spar to the tank assembly wasn't too bad.  It was literally a one pager that consisted of bucking 33 rivets. The only challenging part was ensuring that I only riveted the holes called out in the KAI, as many holes were left open for the next chapter.

I'm starting to get a feel for when a bucked rivet will look good or look like a mess.  I think the key technique is to maintain pretty firm pressure with the rivet gun, but not much pressure on the bucking bar.  Time will tell.

Again, no picture as it really doesn't look any different.

flying instead of building

Well, didn't get out to the shop to do any building because I went flying instead.  I don't want to let my flying skills deteriorate due to spending all my free time building the new plane.  I was getting close to loosing my currency for IFR flights, so yesterday Ed & I took the Cirrus up for a good workout.

The weather was perfect for an IFR training flight.  There was a nice big low pressure system (29.69 inHg) sitting over Ohio yesterday and that gave us a cloud layer from about 1000' to 4000' above the ground.  I flew and Ed observed/coached/critiqued from the right seat.  I flew to Dayton, did a hold and shot the RNAV 24L approach there, all using the autopilot.  In other words, I programmed & observed while the plane flew itself.   That's the Standard Operating Procedure for an actual mission.   Then I disconnected the autopilot but left the flight director engaged and flew the same approach by hand.  The flight director essentially is a display driven by the autopilot that says, "if I still had control, this is what I would do."  Basically, it's a video game -- the A/P moves the cueing display and I fly the airplane to match the cue.  Then I turned off the flight director and flew using just the displayed location data.  I flew all the way back to Delaware by hand, went to the far side of the airport to get aligned with the wind and few the RNAV 28 approach back home.

Overall, 2 hours of a good workout and I feel better about being a competent pilot.

Back to building when I get home tomorrow.

§26 Left -- Rear Spar to Tank

Well, I took a deep breath yesterday and committed to joining the rear spar to the tank.  The section is a whopping 2 pages of actual instructions -- 1 page says to cleco everything together, the other says to rivet it.  All 33 rivets are 470AD4-4 that needed to be bucked since there was no way to get a squeezer anywhere near both sides.  

I am still quite leary of my skills in bucking rivets, hence the trepidation in this step.   Having said that, I'm actually quite pleased with how it turned out.   I am starting to get the feel of how much force to use with the bucking bar.  Counterintuitively, holding it with too much pressure simply causes a lot of noise and not much deformation of the rivet tail.  Obviously, not enough pressure and it simply bounces away.  If you use just the right amount of pressure, the tail of the rivet sets in only 8-10 impacts.

Some of the rivets were in a place that I could only see the shop head and had to hold the bucking bar blindly.   I'm quite surprised that it went well.  I did use the guage to ensure that the shop heads were within spec. 

Tomorrow, I'll finish riveting the spar, tank and inboard mixer box together.  Those use the famous Cherry rivets that are stronger than the regular LP3-4's but are harder to pull correctly.   The sealant should arrive tomorrow or Wednesday and I'll re-seal the Left tank.  They say 3rd time's the charm.  Stay tuned.

§28-14, -16 L&R Aileron bellcranks

 Two steps forward, one step back.    The right tank now holds pressure.  Sort of.   The left tank still has a definite leak at the fuel sender.  I used a cartridge of sealant from Aircraft Spruce, but the gun I bought (that morning) from Home Depot is much too large for the cartridge so I ended up just shoving the base with a spark plug socket as a make-shift plunger.  That made it barely possible to squeeze out the bead of sealant, with the resulting poor performance.   Since then, i've borrowed an appropriate sized gun and will give it another try when the next cartridge arrives from Aircraft Spruce.

I've been holding off attaching the spars to the tanks until they were sealed, but I'm going to go ahead and resume major construction since the leaks are at the other side and can be dealt with in parallel.

I built up the aileron bell cranks.  Took just a day and was a nice, straightforward project.

underexposed picture of the bellcranks

The aileron push rods have specific instructions to be primed.  I learned that just putting them on butcher paper and spraying them with primer, then leaving them overnight to get wet, results in paper that is well glued to the aluminum.  I sanded much of it off, but not all.   I stood the push rods using wooden dowels in the ground and sprayed them again while vertical.   I now have nice camo'ed push rods!

Aileron pushrods drying in the sun

 

§22-19 thru -26 Left

 Well, it's been a minute since I last posted anything here.  In addition to the usual 4-letter word ("work") that always is in the way, I had two very pleasant reasons to take a break from building.  

My eldest daughter came up from Louisiana with her family to visit for a few days.   Here are her 3 daughters and my middle daughter's son & daughter for a total of 5 grandkids.   It was a great, but short, visit.

One of the reasons it was a little short was that her visit overlapped with Thunder Over Michigan, an airshow held just west of Detroit.  My wife recently announced that she wanted to have a helicopter ride, preferably in a UH-1 "Huey", and of the attractions of the show was such a Huey.  Christie went to go stay w/ her sister and we drove up to Michigan and we got the ride she had hoped for!

Finally, back to building!  During the week, I received the extra parts from Van's that I had lost somewhere in the garage.  I finished building up the L outboard aileron attach bracket and got it riveted to the rear spar.  This completes the Left Rear Spar subassembly.   Recall that I had already built up the R outboard aileron attach bracket because of the mislabelled KAI. I thought I might as well build up the R inboard bracket since the workflow was already set up.  I then found the missing ouboard bracket cleverly imitating one of hte pieces needed for the inboard bracket.  This means that I'm missing that piece instead of the one that I just purchased from Van's.   "One step forward, one step back."   Sigh.

Next project:  Clean, scuff and re-seal the tanks.  I bought a larger batch (3 oz) of Fuel Tank Sealant than I typically use, but it's a 2 hr cure time instead of 0.5 hr, and it was actually cheaper than the 1 oz stuff from Van's.   I'll let you know how it worked in the next posting.

Left outboard aileron attach bracket assembly

Removed Fuel Senders

 I can't sleep and it's too late to do anything else, so I'm updating the blog.

My daughter & her family are visiting, plus I'm still working, plus we're going to try to go the Thunder over Michigan airshow tomorrow so I haven't had much time to work on the plane.   I happened to have 30 min to myself before going to work yesterday so I pulled off the leaking fuel level senders from both tanks.

Mounting location of removed R fuel level sender

As you can see, this doesn't look very uniform.   From 10:00 to 14:30, the darker and somewhat smooth color is fuel tank sealant that never even touched the base of the sender.   No wonder it leaked!  The lighter area is where there was some adhesion to the two pieces of metal and I had cut through it. Next session, I will clean that all off down to bare metal before trying again.

Curiously, there was no adhesion to the brass colored metal of either fuel sender.   I will really scuff up those surfaces, too.

Of course, to clean the inside of the tank and remove the debris from this process meant that I had to remove the inboard fuel tank access panels, too.  Those had been sealed with fresh fuel tank sealant and the showed proper, evenly 'wetted' distribution of the sealant after I got them cut off.  That made me feel better that I can apply things evenly if I'm using fresh sealant.

Both tanks, with senders and access plates removed. 

Good night.

§25 -- inboard mixer boxes

Section 25 is the inboard mixer boxes.  These were almost as easy as the outboard ones, but there are a few differences; mostly just a few more parts.  That made it a bit more complicated to ensure that I had the correct orientation when I built the other side, as I have a somewhat difficult time with L/R spatial orientations.

One trick published in VAF was to mirror the PDF images from the KAI in software.  Several VAF members have gone so far as to print mirrored pages of the whole book, but that's overkill.  I did something that was fast & cheap and just took quick pictures w/ my phone of the relevant pages.   10 seconds of editing on each page to mirror each one and I was in business.  Having just built the left version, I didn't need to refer to the printed notes very much and I concentrated on the object I was holding and comparing it to the image on my phone.  In the future, I'll use my iPad instead because of the larger screen and its attached stand.

Remember the NAS1097 rivets I talked about the other day?  I said that there were only 4 in the whole kit.   Wrong.  There were only four of the AD3-4 and I totally overlooked the bin that held 36 of the AD3-3.5's.  Those were the size I was supposed to use earlier.  As a result, when today's kit called out for the 3-4's I had none.  I elected to use AN426AD3-4's to achieve the proper length and deal with the larger head by accepting the larger countersink needed to flush the larger head than the called out AN1097.  The primary advantage to the 1097 is the ability to be used in very thin material, but the piece that accepted the rivets in question is quiet thick-- 0.063", so I ended up with something stronger (not needed) and the correct length.

Inboard Mixer Boxes

BTW, I'm determined to provide my grandson an early introduction to the project.  He just turned 8 and has a very short attention span, but I did manage to show him 5 different rivet setting techniques before he timed out.  Baby steps! :)     I have 3 granddaughters visiting later this week.  One or two of them may be interested, too!

Layne, learning about squeezing rivets

§24 Left; OB Mixer-Rear Spar

Like building the outboard mixer box itself, installing it into the rear spar was relatively straightforward.  It involved being very careful about which rivets were installed into which holes, since the structures had multiple pieces of varying thicknesses.  There were a lot of rivets that had to be driven, including some where it is really difficult to get your hand in place with the bucking bar!  I'm very glad I spent the money on the tungsten bar -- its small size came in handy for just this occasion.   I suspect I will never need another bar that doesn't have a unique shape/size.  (There are bucking bars for sale specifically for doing some hard to reach rivets in the tail cone of the RV-14.)

I took a picture, but it's not worth publishing because it looks just like the last one of the rear spar & ribs.

§23 -- outboard mixer boxes

Section 23 is a very short, straight foward chapter that builds the Outboard Mixer Boxes.  It's literally just installing 1 nut plate and riveting 4 pieces together with 16 of the easy-peasy pull rivets.   It took me about 2 hrs to do both L and R sides.

I decided to do them both because I do have a lot of trouble with mentally mirroring the drawings.  I built up the Left in its entirety, then set up the parts for the R and used the physical structure as my mirror source.

I learned a little bit about rivets.  The kit calls out for a very specific rivet, NAS1097AD3-3.5 rather than the much more common AN426AD3-3.5.  In fact, the entire wing kit has just four of the NAS rivets.  They are to be used in shear loads only, as they have a very small head and won't resist much axial loading.    They are typically used in very thin material.   What's odd is that Van's almost always called out the AN426's for similar applications and the material in question was actually pretty thick, 0.050", so I have no idea why they went to the trouble of stocking these specifically.  Oh, well.

L & R Outboard Mixer Boxes

Leaks identified

While working on the R spar, Marc came over to help figure out the tank issues.  He's also an engineer and I wanted a fresh pair of eyes on the problem.  He agreed that there should be no leaks based on my procedure and his visual inspection.  Back to testing: we split up the tasks of one person pumping and the other spraying bubble soap, but never saw any bubbles.   We finally took the compressor and blew air into the tank.  We could feel a breeze on our fingers on the inboard edge (with all of the connections) but couldn't make any bubbles appear nor feel our way to the leak.

Rather than using expensive, toxic, smelly and flammable avgas I decided to do an old fashioned test.  We filled the tank with water from the hose.  Viola!  The Proseal around the fuel sender leaks like a sieve!  Water streamed from the entire circumference.  Mystery solved.

This also validated my gut feeling that it was a systemic issue.   Recall that I used left over Proseal that had been in the freezer.   While working with it, it was appropriately sticky and gummy and I thought it was OK, but apparently it was by then too viscous to actually flow when I tightened down the fuel sender plates.

I'll order some more Proseal (or B2 sealant as it is now known) and re-do the senders when it arrives.  I'm feeling much more optimistic that we'll get something that is water tight next time.

§ 22-4 thu -17 Left, -18 thru -21 R

Got lots of building done this weekend.   The rear spar is the topic of construction for the next 4 or 5 chapters.  § 22 is pretty straightforward, if somewhat long.  I was really hoping to be able to complete the entire L rear spar on Saturday, but ran into a minor glitch.    

If you notice the title, I suddenly switched from building the L rear spar onto building the R rear spar.  Curious, no?    Page 18 calls out starting with W-15016B-002.   That's odd.  a -002 part implies that you've probably come across the corresponding -001 already.  I proceeded until I came to the conclusion that I had indeed built the corresponding assembly (outboard aileron attach point) for the other side.

No problem, I thought to myself.  I went to the parts shelf but for the life of me, I couldn't find the expected -001 part.  My inventory sheet shows I had it in my hand at one point, but neither myself nor my wife could find it in the shop.

I'll order another one this weekend and will eventually get to finishing the L rear spar, but during the meantime, there's other stuff to be done so I'm not stuck.

most of the L rear spar

Quick update

Just a quick update so you know I'm still here.

I've laid out the parts for the next section and feel pretty good that it will come together quickly in the next day or so.   

I finally received the last few back ordered parts from Van's.  My wing kit is now officially complete.  

There is much gnashing of teeth on VAF regarding some misaligned holes on a few wing spars.   Those spars are apparently ~$3K each!   I dug mine out and clecoed together the areas of question and the holes are well aligned, so I don't have to deal with getting Van's to replace them.   

Marc is a partner in the Cirrus and we're going to go flying tonight.  Tomorrow, he's going to swing by the house and I'll enlist him in helping me find the source of the leaks in the tanks.

Setback -- The Fuel Tanks Leak. A lot.

Well, I finally had an opportunity to work on the fuel tanks again.  I lost a day or so because I never read the manual on the little bicycle tire pump and I was putting it on incorrectly.  I thought it was defective and went to the aviation division of Walmart to find a pump with a different kind of connector.  There weren't any.  There was, however, one brand that thoughtfully provided an instruction card and I learned I had been trying to attach the pump while it was in the locked position.  Duh.

I got home, correctly attached the pump and tried to pressurize the left tank.  The balloon barely quivered with each stroke.   Damn.

Armed with my granddaughter's bubble soap, I put the tank on stands out on the driveway and liberally soaped up all of the seams, the access panels, the fuel sender, the supply lines, vent lines and balloon neck.   Nada.  I can't generate any bubbles at all.   I'm pretty bummed.   I washed off the soap and put the tank back on a solid table.   I rigged up the right tank and got equally nowhere, but I didn't bother to soap it up.

I've learned not to do anything when I get into a spot like this.  By doing nothing, I can't make it worse.  The fact that both tanks are completely incapable of holding any pressure at all implies that I'm missing something fundamental that will probably be obvious in retrospect once I find out what it is.

Tonight, I'm going to think about options.  I'll write to Van's and ask how they pressure tested the tanks without them being sealed and see if that sparks any intuition.  I'll look into acquiring a 4' x 6' x 1' plastic tub and might try to immerse the tanks under water and look for bubbles that way. (That's going to be 240 lb of buoyant force to deal with, so I'll need some brawn to help!)   I'll check w/ some RV builders at DLZ and invite them to come help me troubleshoot.   Something.

Tomorrow is a day off and I don't want to throw it away by doing nothing at all, so I'll start on the next section of constructing the aft spar and ribs.  As long as I don't attach anything to the tanks, I am maintaining their current state and not impairing my ability to troubleshoot later.

§21-11R, -13. Sealed access plates R tank, installed fuel drains

As expected, it wasn't difficult to apply B2 sealant to the access plates on the top of the right tank.  Overall, it took about an hour and about 3/4's of the jar of sealant.

As expected, it was much more difficult than it should have been to install the fuel drains.   The instructions on page 13 are deceptively simple -- Install (1) into (2), where (1) and (2) refer to the fuel drain and fuel tank, respectively.  It doesn't mention using anything to create a seal, but I know that those types of threads (NPT) aren't actually fluid tight and must have a sealant of some sort.   Basically, it boiled down to using B2, as is used everywhere else, or Loctite 565 which is called out in a different chapter but never mentioned in the actual instructions.  I posted a query on VAF and was told RTFM (section 5) where it generically calls out Loctite 565, so that's what I went with.

As mentioned a few posts ago, I had tried a simple trial fit by installing (finger tight only) those components, and somehow managed to strip threads.  I wasn't really sure if they were stripped inside the tank (horrible) or just on the $30 part (not too bad).   

I researched the drain and found that it was a 1/8" NPT.  I couldn't find any technical description of the threads for the part from Van's.  It appears that all 1/8" NPTs are 27 pitch but that was only because that was the only pitch number I ever encountered and it was rare to find it at all.  I bought a set of cheap taps & dies at Harbor Freight that included the desired NPT.  I've tapped internal threads before, but never cut or chased external threads.

Some scrap Al from the RV12 was used to make a test hole with the tap and I was able to thread the fuel drains into that.  This confirmed that they were indeed 1/8 NPT 27.  I debated chasing the external threads on the drains, but wasn't sure which side of the die was the starting side.  Since NPTs are tapered, doing it backwards would probably destroy the part, so I deferred.  In retrospect, I think running the drains through the test hole actually chased them a little anyway.

The tap was used to very gently chase the tank.  I only used finger pressure and no tools.  The drains got gooped up with 565 and I tried to install them.   Nope, the threads wouldn't engage.  I finally got them to engage and tighten by pushing up on the drain with my thumb to and apply a fair amount of axial load while gingerly rotating them with a closed 1/2" wrench.  Finally, success.  It only took an hour to install two bolts.

Right Fuel Drain

§21-07 thru -10, -11 L, -12. Installation of fuel senders, access ports, fuel caps

Two days ago I got a lot done and pretty much finished sealing up the Left tank.  I ran out of time, energy and sweat and didn't seal the access plates on the Right tank, but that is now one of those "just get 'er done" things since I've gone through the process and know what / how to do. 

To explain; we left off with both tanks inspected and rinsed w/ 100LL avgas.  There was no debris and we found nothing in the rinse process.  The tanks had a few days to dry before I got to work on Monday.  The plans call for bending the float attach arms for the two fuel senders and give some engineering drawings to show how to do it.  I did both of them backwards.  Luckily, it turns out that that configuration is perfectly acceptable.  The only variation is that the float arms are 'pointing' in the direction opposite of the drawing, but this is on an axis that is parallel to the actual pivoting, so it makes no difference.  (sin 0° = sin 180°).

The R fuel float was very stiff and would actually stay in whatever position I put it. This is not going to give an accurate fuel level measurement since the goal is for the float to fall by gravity and float by buoyancy in the fuel.   I actually didn't realize this until after I had applied the pro seal (or "B2", as Van's now calls it) and was in the middle of trying not to make a thorough mess.  I was able to gently apply a little bend in the mechanism such that it no longer was binding and free falls properly.

Right Fuel Sender, Internal View

I got both fuel senders sealed in place with the left over B2 sealant from the second flap.   It definitely was harder to work with and was getting stringy towards the end, so I'm pretty sure that it only had a few minutes of shelf life with which to work, but it was still spreadable enough that I'm comfortable that I have good seals on the fuel senders.   We'll find out soon.

Right Fuel Sender, External View

The inspection ports on the Left tank weren't too bad, but I was surprised that I used up most of a jar of B2.  I have one left in the freezer to do the Right tank later today.

As mentioned last time, I stripped the threads from the L fuel drain.  I have the 1/8' NPT tap from Harbor Freight and will address that later today, too.  With that done, the R tank will be curing for 24-48 hours and I'll start pressure testing the Left.

Stay tuned. 

§21-06 Fuel Tank Inspection & Wash

Well, I got all prepped and studied up for doing section 20.  I got the tanks out of their containers & unwrapped them and was pleasantly surprised that section 20 was completed by the factory.  One more down w/o any effort!

Section 21 is all about prepping the tanks and sealing them up.  I inspected the insides with a video scope and found them to be spotless.  There were no 'hanging chads' of sealant, any debris to be found, and all of the specified internal passages were open. 

The book says to fill each tank with 3 or so gal of 100LL and throughly rinse the insides, including turning the tanks upside down.  I looked at the 4 big open inspection plates and decided that it would be a good idea to put the plates on, otherwise we (Lada & I) were going to just pour all that avgas all over the garage.  There are two fuel pickups (6D) and two vent lines (4D), but the kit only included 1 each of the end caps, so fuel did make a bit of a mess.  Lada took the brunt of  the spill but didn't complain because she has a curious appreciation for the smell of oil & gas and stuff.

I did try to stem the mess by hand threading the fuel vent lines into their ports.  The L tank was straightforward, but the right side wouldn't thread.  I gently applied some torque w/ a wrench and promptly sheared the first couple of threads inside the coupling in the bottom of the tank.   I did some research and verified that it's a 1/8" NPT which is readily available at Harbor Freight.  I'll pick up a tap in a couple of days and will very gently chase the threads and try again.

Left Flap completed, §36-24 thru -26

Well, yesterday I said that I had estimated it would take 3 hr to complete the Left Flap.  I must be getting better at this (or at least lucky) since it took 2:50 to finish the job.   Lada helped during the pro seal application and fitting the trailing edge.  It's much easier with 4 hands instead of just 2.  I propped the skin up with some rags under the skin and against some ribs.  I only used about 1/2 of the jar of proseal and made essentially no mess.  Then both of us flexed the trailing edge around the back and it was done.  I spent the rest of the afternoon pulling the rivets, putting the ailerons & flaps into moving blankets and then cleaning the garage.  All in all, a very satisfying afternoon.

 completed Left Flap

both ailerons & both flaps

All wrapped up!

about 1500 pop-rivet mandrels

Right Flap completed §36-25, 26

I got off to a late start today because I worked a night shift last night and then had a 4 hour morning course to renew that pesky ATLS certificate.   I slept until 5:00pm before heading out to the shop.

I left off yesterday with the right flap fully skinned but not yet riveted, so all I had to do this afternoon was  pull rivets and finish the FL-15500-002 Right Flap. 

FL-15500-002

Close up of the vortex generators on the upper surface

Once that was done, I got to work on the left side.  The lower/training skin was peeled & deburred.   I hadn't deburred the vortex generators on the leading/lower skin so that got done, too.   I've fully clecoed the leading edges of the skins, but will stop here.  Tomorrow, I will rivet the leading edge & generators together.  That will provide excellent alignment for the one-and-done fitting of the trailing edge once the B2 sealer is placed on the rear lip.   It should take about 3 hours (so I'll budget 6) to finish before I go back to work tomorrow night.

§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.

The building has finally begun! (§34-05 thru -09, Left)

OK, so now we are officially started on actual construction.  It took about 3 hrs de-clecoing the Left aileron skeleton, deburring all of the edges and holes, reassembling and finally using rivets to hold things together.  

Behold -- the Left aileron skeleton

It took me three tries of remembering to ensure that all of the ribs were properly aligned before I started riveting.   The new squeezer is definitely different from using hand squeezers.   While it is easier to actually set the rivets pneumatically, it's a very heavy tool and puts a lot of stress on my thumb (which is not it as good shape as it was 15 years ago!)  I actually found that using it L handed was pretty workable,  I had to drill out my first rivet when I missed being on center with one and it was nice to realize that I remembered how to remove one.  Specifically, I used a #53 bit to make a pilot hole then a #40 to remove the bulk of the rivet and finally a pair of pliers to easily remove the remnants.    The pulled rivets went in without a problem and the old rivet puller showed no signs of age.

I won't have time to work on it today.  Tomorrow I am expecting it'll take me about half the time to assemble the R side.  Stay tuned.

Oh, BTW, today I'm supposed to get the delivery of the backordered and missing parts.  Fingers crossed!

The building has (almost) begun!

We were out of town for the week, playing grandpa & grandma with my daughter's family outside of New Orleans.   We got back late Friday night and Saturday I worked on one of Van's practice projects.  Specifically, there's a simple aluminum box with their logo cut out in front and illuminated from inside by a strip of LEDs.   I already built one and it was a good project to remind myself about how to cut, dimple, deburr, cleco and rivet things together.   The project comes with enough rivets to use either the default LP3-4 pop rivets or you can use a rivet gun.  I elected the latter as I have no significant experience driving rivets.  Alas, the rivet gun I borrowed today didn't work for some reason, so I shelved the rest of the practice project for now.  I will finish it using driven rivets whenever I get a functioning rivet gun.

Having put that on the shelf, I finally started working on the kit itself.  The instructions just say "here's the Left, you just mirror it in your head when you do the Right."  The user group has published a Wiki with errata & gotchas.  One of the first ones is that some of the parts are mis-labeled with respect to orientation.   Van's nomenclature leaves much to be desired.  As far as I've been able to deduce, parts that end with -001 are the first ones designed in CAD.  If a mirrored part is required, it gets a -002 suffix.  Note that these have nothing to do with the left or right of the airplane.

Armed with all of the trepidation that these factors engendered, I elected to do no cutting or bending or anything else that is not reversible.   Instead, I clecoed both of the aileron skeletons side by side.  Even so, there were several steps that are (IMHO) poorly illustrated in the KAI.   I'd love to see orientation vectors (up, fwd, outboard) next to many parts.   I did, in fact, cleco several things upside down or swapped inboard vs outboard.  I was very happy that I hadn't cut or drilled anything!

Right and Left aileron frameworks

When I return to the shop on Wednesday, I'll disassemble one framework, remove the plastic, deburr, etc, and start riveting.   I'll go back to my usual pattern of labeling each post with the pages of the KAI.   Talk next time!

Completely Unpacked Wings

Well, inventorying the small parts only took about an hour or so.   Van's has changed their method of packing small parts and are now using a collection of "tackle boxes" as they are called on VAF.  They are translucent plastic boxes with customizable inserts that are postioned to make ~25-30 little part bins.  Van's then printed a 'parts map' that physically overlays the bins for easy identification.  Think 'box of chocolates' from Valentine's Day with the candies labeled on the inside of the lid.    VAF had a few grumpy comments about parts that spilled over, but mine were just fine.

(I did forget to double check the length of the Cherry Max rivets that I received.  Some very early kits apparently had the wrong length of those parts.)

Tackle Boxes of Small Parts

Despite my reticence about throwing away good material, I just cut up the crate into <5' chunks and folded and tied all of the heavy duty cardboard into individual bundles and drug it all to the curb.   I hope it all got picked up today!  (My wife has not texted me anything to the contrary, so I'm hopeful.) The garage is now officially a workshop and ready for business!

Workshop (neé garage),

 generously donated by my loving wife.

Mostly Unpacked

 I finished unpacking the big crate yesterday.  

Big Empty Crate

I drastically overestimated the shelf space for small items and underestimated the space needed for the skins & spars.  Duh.   I'm not completely happy with where I needed to put everything from the point of view of convenience in working on them, but I am happy that everything is either properly supported or tucked away such that they won't get bent.    There were only 3 pieces that weren't included and I'll have plenty of time to send Vans the discrepancy list before the 30 day window closes.

I opened one of the small crates and just looked at the wing tank, but didn't remove & unpack it yet.  I think I'll take the tanks out of their boxes and discard most of the packing material to get some more room in the shop.   

Small Crate w Wing Tank

I have to figure out how to get rid of the crate & pallet, though.  Even if I could just drag them to the curb for trash pickup, it offends my soul to discard perfectly good plywood.  

Tomorrow I will tackle the 3 tackle boxes of small parts and do their inventory.  I expect that I'll be able to send the discrepancy email to Vans before we leave for vacation next week.   When we get back, I will start my first bit of actual work and assemble another practice kit.  That'll help get my muscle memory back for working with sheet metal and give me something to use to learn to drive rivets.  One of the big selling points of the RV12 was that there were no driven rivets.  Not quite the case in the RV-15, so I borrowed a gun and will get some tutoring and build up the practice kit before tackling the main project.

Wing Kit Arrived!

Yesterday was a big day with the long awaited (9 months since original deposit) of my RV-15 Wing Kit (except for the spars, but they should arrive in about a month or so.)  Van's shipped via a company named ABF.  ABF called me the other day and set up a delivery for Friday May 8th.  Then the status page for the order said May 11th.  I called and they confirmed the 11th.  I pointed out they hadn't notified me about the change, and that the 11th wouldn't work for me.  They said 'OK' and said they'd drop it off on the 8th.  no apologies or anything.  Weird. 

OK, so the delivery window was from 8am to 8pm.  Because I never procrastinate, the garage was completely cleaned and organized and ready for the deliver.  Not.  So at 8am I check the status page (loading) and got to work in the garage.   By noon, I had converted a garage w/ nearly 3 years of cruft & debris into an acceptable and clean workshop.  

Clean & Ready Workshop

Around 1pm, the status page finally said 'out for delivery' and I started to trust them that they would deliver and not make me wait until next week.   Around 4:30, the truck showed up.  The driver cursed that they didn't give him the right equipment to unload it properly so I enlisted my neighbor, Kevin, and his friend and the 4 of us eventually manhandled the crates into the workshop.

Wing kit boxes in the workshop

main box, before opening

Main box

I tackled the main box first. I had to drive out to the hangar to get a Dremel tool to cut the metal straps and grabbed my drill press, band saw, grinder and a bunch of loose/small tools.  I had put off getting tools until the garage had been cleaned and converted in order to not add to the clutter and further drive myself crazy.  I spent about 2 hrs excavating a phenomenal amount of crushed brown wrapping paper out of the box to get to the result you see above.  I'll need to figure out how to package the paper so it can be picked up for recycling, and then I'll tackle the inventory.  BTW, I have 30 days to report any discrepancies for free remediation & shipping.