Rudder (re-visited) and status update

I had an issue with the rudder skeleton that I needed to re-visit.

Decided to scrap this and order new parts.

Anti-Servo Tabs

I couldn't do too much with the ASTs when I was ready for them.  If you'll recall, the two piano hinges were lost in the shipment.  Since I got all the replacement parts.. and since I'm done with the HS.. I thought it was a good time to go back and finish these up.

As a refresher..

I had previously sanded the edges, alumiprepped and primed the inside skin, ribs, and the outside skin that mates with the piano hinge.

The piano hinge was cut to 33 eyelets, and the drilling template was used to drill holes under each eyelet.  There are two ways to use the template -- pay special attention to the notches in the template.  With the AST hinge, the notches sit up against the eyelets.  With the HS, they do NOT sit up against the eyelets.  Of course, the holes were deburred and the hinge was cleco'd in place.

The bottom skin was cleco'd and riveted, along with the AST spar.  There was a question as to whether the horn's rib's flange sat inside the spar OR between the spar and the skin.  After reviewing the diagrams closer, it sits inside inside.  The question was raised because it might seem more appropriate to have the spar (thick material) sandwich the rib flange (thin material).. but whatever.. thats how it was designed for whatever reason.  I tried my best to keep all the material clamped down before pulling the last pop rivet on the leading edge skin.. can't really use a cleco to help.

The AST Control Horn was riveted.  The hinge was riveted in place.  Be sure that there is ONE open hole next to the Control Horn, as seen in the above diagram.

After that, the top skin, including the top leading edge is cleco'd and riveted.

The ASTs are really straight forward and I'm surprised Van's didn't have this as the first part to be assembled.  Things to note here is that the rib that the Control Horn is attached to is different than the other 3.  Also note the direction that the flanges go.

 The tabs are done.

Having the right tools...

TIME: 3 HOURS

I riveted the two aft skins to the HS.  Nothing exciting to see.

I was treated to a problem I couldn't solve without the right tools though...

There are four AN3 bolts (like the one at the top of the page) that hold each horn on.  The two bolts on the front-side (seen -away- from you in the diagram), are shorter than the two bolts on the rear side..   Hence the AN3-4A vs AN3-5A.  The "A" means that there are no safety-wire holes drilled through the bolt's head.

The fasteners on the front side are clear..  AN3-4A bolt, a thin -10L washer under the head .. then through the the horn.. through the spar and into the nutplate:

Fasteners on the forward side of the spar

The fasteners on the rear side are more complicated.  First, you need to find out what shim you need in between the spar and the horn.  I had used some feelers, but it was easier to just try and see how many -10L "thin" (0.032") washers and/or -10 "thick" (0.063") washers i could slide underneath.  I was able to slide only ONE -10L thin washer underneath.  I tried two, as well as a -10 washer.. no dice.

Fasteners on the rear of the spar

Based on what size shim you needed to use to eliminate the play between the spar and the horn,  then you have to figure out how many washers to put under the bolt's head.   The total of the thicknesses of:  shim + horn + washer(s) =  between .220" - .255".

Simple enough right? .. we know the size of the -10 and -10L washers they are pretty standard.. and exact.. but.. what is the thickness of the horn?  They mention in the example that its 0.056".  Is my horn really that thick?  My calipers were at home in a drawer.   Bring the part home for the night.

I took several measurements around the holes of both horns.  They were all very close to 0.059".  Ok, now we have all the information we need.

The total build-up is:  .040 spar + .032 shim + .059" horn = 0.131".  Therefore, we need between 0.089-0.124" to bring the build-up into range.   A  -10 + -10L washer combo would be 0.095" .. thats good.    How about TWO -10's?  That'd be 0.126" and that's slightly over the acceptable range.

Not taken into account is the primer that is on the inside and outside of the spar.  Its probably negligible, but it still counts for something... maybe 0.001"?

So its settled that we need a -10 and a -10L washer under the heads and the total is 0.226".

Horizontal Stabilizer: Finishing

TIME: 3 HOURS

I put the AST hinges on the rear of the HS.  Surprisingly, almost all of the holes I drilled in the hinge using the hinge-drilling-template lined up exactly.  I found that I had to debur and sand the template just a little in order for it to for in snap in between the eyelets of the hinge.  Its a nice simple and low-cost way to drill holes in hinges.  There were a few holes which I couldn't insert the rivets into -- and that's probably do to a little primer inside the hole.

For instance, while I was placing rivets in every other hole..  there would just be a few random ones which wouldn't go in (at least not without some force).  I cleaned out the hole with a #30 and they slid right in.   Cleco every other hole, rivet,  remove cleco, rivet remaining holes.

The rear-skin splice was match-drilled with #53's.  These are really tiny holes, I think its for safety-wire in order to hold the hinge pins in place.  ERROR: When I match drilled the #53 holes into the rear-skin, the splice plate was upside down.  So I have two tiny holes in the skin which don't go all the way through [the splice plate].  Seems like this is my first permanent error.  Oops.

The counter-balance arm, lead weights and rear skins of the HS (i'm not sure what to call them) will be for tomorrow.

Horizontal Stabilizer: Part 5/5

TIME: 4 HOURS

Skinned the LEFT side of the HS.  Nothing really new here.  Same techniques applied.

Just a lot of rivets.  I wish my pneumatic riveter was hanging from the ceiling on some sort of spring so I didn't have to hold it anymore.  The rivets on the trailing edge (for the AST hinge and for the outboard trailing edges of the HS will be left for tomorrow).

Horizontal Stabilator: Part 4/5

TIME: 7 Hours


We last left off with a HS skeleton.  Today I had to put some hardware onto the spar such as the hinges and the up/down stops.

I started to screw in the AN3 bolts hinge stops.  One of the bolts wasn't catching on the nutplate.  I started thinking that maybe the nutplate's threads were busted.. and the work involved in trying to change the nutplate.  I was using a 3/8" socket to screw it in.  I thought maybe if there was something to press it into the hole as it turned, the AN3 bolt would catch the threads.  What tool did I have that would do it?

Just drop a big rivet into the socket!  I'll be able to push the AN3 bolt and turn it at the same time.  Great.  Now that the hinges were secured to the front of the sparbox with four AN3's each, I then placed the hinge stops (2 per hinge) into the hinges.

In a previous post, I mentioned how Van's specified that the hinge stops were made from aluminum tube and they were 21/32"  -0/+1/32 tolerance.  Now I see why the tolerance was so strict.  they fit in between the hinges perfectly.  Again, these were secured with an AN3 bolt along with a nylock nut.

I also spent about an hour re-doing this because I was confused about what the proper torque should be for all of these bolts.  So it appears that every bolt size (forget the length of the bolt.. its the width of the shank that matters) has a different torque value.. and those values are listed in Section 5 of the manual.  The torque for an AN3 was listed between 20-25 inch-pounds (and 28 inch-pounds for an AN3 thats secured with a nylock nut).  The bolts didn't really seem to go anywhere.

I found that what I had to do was to first measure the resistance of the bolt going in, then add that to the 20-25 in.-lbs.  Nut plates are sorta mis-shapen and it takes a lot of force to re-shape it as the bolt goes through it.  After all the threads of the nutplate were engaged, I tweaked the settings on the torque wrench to find out how much force it took just to turn the bolt.   I then added that value to the rating for the AN3, 20-25"-lbs.  Therefore, I set my wrench at 45 and screwed them in.  45 also "felt" right based on the size of the bolt.  So the result is that the actual force exerted on the bolt's shank ends up being 20-25 (i used 25) .. and the force used to actually turn the bolt through the nutplate doesn't really count for anything as far as the tensions are concerned.. but you have to take them into account when screwing the bolt in.  AN3's are apparently certified to 60inch-lbs, so we're definitely not over-torquing these.

Ok.  That was a couple hour detour that I wasn't expecting.  Continuing on..   the next step was to put the skins on.   I found that the best way to do this was to use only a few clecos to get the skin lined up --  two clecos on the inboard-most holes of the sparbox.. two on the outboard-most.  Then place rivets in every other hole.  The rivets get the holes lines up 100% -- and with so few clecos in place, its easier for them to move the skin a little in whatever direction they want as they're inserted.   Insert rivets into every other hole,  cleco every other hole.  Read the directions again.  Start riveting.

Horizonal Stabilator: Part 3/4

3 HOURS.

Put in a few hours tonight.  Last visit to the hangar, I primed all of the attaching hardware to the HS spar box. (I still have to do one skin, as it got dark out before I was finished).

Most of the work today was attaching the 90 degree brackets for the rear ribs, removing some material from the front of the front ribs, and attaching the rear and forward ribs.

Rather than take a bunch of photos of me pretending to assemble things, its just easier to take a video and narrate what was assembled here.   When you're using 3 rivets to secure a part, it seems like you get a more exact match when you put a LP4-3 in the center hole, THEN put clecos in the two remaining holes.  If you do it in reverse -- 2 clecos then a LP4-3 in the center hole, then that center hole may not be lined up exactly for the LP4-3 to just slide in easily.  With two clecos in place, its hard to re-align the parts by forcing that center LP4-3 in.  The clecos hold the part too good for that.  So,  get your exact match first by using a LP4-3, then hold the part in place with clecos.

Horizontal stabilator Part 2/4

Put in another 7 hours at the airport today.  I was hoping to get the stabilator buttoned up.. or at least painted..   but I got as far as knocking the edges off the ribs.  I need a faster way to do this.  I need a belt sander.

I sometimes forget to mention a lot of the small side things that need to be done.  For instance, I needed to cut four  21/32" long spacers from aluminum tubing.  Not a huge thing to do, but they were calling for -0 / +1/32" tolerance, so I needed to go a little slower and make good measurements.

Here's what I started with today:

While I was making the second video today, I noticed that there were two rivets in the wrong places.  I think I had pointed them out in the video and immediately realized they didn't belong there.

I spent some time taking the vinyl sheeting off of the skins to start to get them ready for priming.  

Horizontal stabilator Part 1/4

Today I also did a lot of work on the Horizontal Stabilator.  All of the HS doubler and spar countersink holes were drilled earlier this week while I waited for paint to dry..  so today's progress was good.   Here is what we're building:

Today's work consisted of building the spar box -- thats the HS-1202 Forward main spar, HS-1216 Aft main spar, HS-1211 x 2 (top and bottom).  There are 4 square ribs inside the spar box and some doubler plates.  Since good progress was made, here's today's video:

More progress was made today after the video such as match-drilling the upper and lower control horns, match-drilling the counter-balance flanges on the forward and aft side of the spar box, match drilling the counter-balance arm..  disassembled everything and deburred.

Drilling through steel (the counterbalance arm) was tough.. unwelcomed change from drilling through aluminum for the past two weeks!  

There was a little art involved when drilling the CB arm.  Remember, here is what is looks like upon final assembly:

They have you rotate the arm and the two flanges for it by 90 degrees.  This is so that you can drill holes into the flange & arm straight down.. rather than sideways.

So the deal is to insert the arm through the front flange.. and then through the back flange.. until the arm is flush with the back flange.  Easy enough...  but then you have to rotate the arm so that the flat end of the arm is flat, like you see in the above diagram.

I had a digital level which measures down to 0.1 degrees..  I placed it on the spar box and it read 0.5 degrees (i guess my workbench isn't exactly level.  I then placed it on the flat end of the counter-balance arm... I rotated it until it also read 0.5 degrees.  I used a C-clamp to lock the arm in place (to the rear flange)..  then started to drill #30 holes, then final-drilled #12 holes.

Tomorrow, I should be able to get the spar box done and all the ribs attached.  Doesn't sound like a lot, but I haven't prepped or painted any of tomorrow's parts yet..  After that, i'll be stuck until I get a piano hinge... but hopefully my shipment will come by then.

Anti-Servo tabs

Since the rudder is on hold for a little while.. We'll proceed to the next item which is the Anti-Servo Tab.

The AST is a trim tab for the stabilator.  Its a small part.. smaller than the rudder :

As you can see, its pretty straightforward.  There are two of them, one for the left stabilator and one for the right.  There are 4 ribs, a piano hinge and a control horn.  The left and the right ones are mirrors of each other.  I was able to get as far as getting the ribs in place, match drilling some holes.

Unfortunately, the piano hinge was a part that was lost in the shipping disaster of July.  Speaking of which, my replacement parts arrived at the local Old Dominion terminal on Tuesday and I scheduled delivery for Friday between 8AM - 1PM.  1 PM rolled around, but I didn't call them up until 5PM -- delivery guys are usually late.  Well, OD informed me that they ran out of room on the truck and it wasn't even loaded on today.  Nice of them to call me and tell me that.

So the AST is on HOLD until my replacement parts delivery is re-scheduled.

Rudder

Normally, after the V-Stab, the rudder and the Anti-Servo Tab is the next item on the list to complete.  I'll be going out of sequence in a little while..  more on that to follow..

I started work on the rudder.

Here is what we're trying to build here:

--insert graphic here--

After the V-Stab, the rudder should be a piece of cake.  Its smaller.. one spar with  with 4 ribs on one side, a couple doubler plates and a hinge on the other.  Well.. I screwed up.

Here's how its supposed to look.  The spar's flange is towards us.. and this is the side with the hinge.  The opposite side is the side where the ribs are.  In this guy's photo, you see the upper hinge mounted on two doubler plates, mounted onto the spar.

I wish I had taken photos of my mistake, but I was too frustrated and just wanted to fix it.  I put two ribs on -this- side of the spar.  I drilled out 8 pop rivets and put the ribs on the correct side.  Not a big deal really.

Then.. I realized that I had put all those rivets in (as shown above), and forgot to put the rib on.  See that center line of rivets between the two hinges?  Those are what hold on the rib on the opposite side.  This is a bigger problem.  I had to remove one hinge (4 rivets),  then remove the 4 error rivets.  Then I realized I didn't have enough clearance to squeeze on 4 new rivets (and the rib), so the other hinge had to be removed.  12 rivets total.

In the process, I mangled some holes:

 
I mailed Van's and I expect they'll tell me to re-drill these holes and use a wider rivet.  If this we're an E-AB airplane, I'd just go ahead and do it, but since it's an E-LSA, I'd like to get their OK on it.  So long story short, the rudder is on HOLD.

Vertical Stabilizer Part 1

I skipped a few days of blogging on the Vertical Stabilizer as I was too busy actually working on it!

The edges and holes were deburred.  The edges were sanded to a "won't cut your finger" smoothness.  Ribs were sanded, alumiprep'd and primed.  The skin was alumiprep'd and primed.   I used EkoPrime single-part primer Stewart Systems.  Its not resistant to solvents, but there shouldn't be any in the tail.  Unlike epoxy, any unused primer can be dumped back into the bucket for later use.

Here is a tour of the skeleton:

I cleco'd one side of the VS and before doing the other side, one last look.

Finished riveting one side.  Tomorrow I'll do the other side and that will pretty much complete the VS.  There are two nutplates (to attach the forward VS cover) that I couldn't get with the rivet squeezer so I'll have to borrow someone's rivet gun and bucking bar this weekend - should be a 10 minute job.

Today: 5 HOURS;  Tail TT: 12 HOURS;  TT: 12 HOURS