Empennage Installation Continued (4/25/14)

1.7 Hours –

The first thing I wanted to do was to get the elevator pushrods reconnected to the bellcrank in the fuselage.  I struggled reaching these parts the other day, but then I realized that the forward top skin still hadn’t been riveted to the fuselage and could be removed to ease access.  Once I took a few clecoes out, and could duck under the side of the skin, getting the bolts through the rod ends and bellcrank was a piece of cake.

After the pushrods were installed on the bellcrank, I reattached the aft pushrod to the elevators.  With everything connected, I placed the bellcrank in the neutral position and then checked to see if the elevators were also neutral (in-trail).  The elevators were slightly up, which meant the pushrod needed to be shortened.  I removed the pushrod from the bellcrank, gave the rod end a couple twists and then reconnected everything.  With this slight adjustment, the elevators and bellcrank were both perfectly neutralized.  I then double checked that more than half of the threads on the rod ends were engaged (well over half on the aft rod end, and almost all on the forward), torqued the jam nuts on the pushrod and marked them with some torque seal.  The pushrod should not need to be adjusted anymore (hopefully).

Both elevator pushrods are now attached to the bellcrank inside the fuselage. The length of the aft pushrod has been set, but the forward pushrod still need to be attached to the controls.

Next, I bolted and riveted the up elevator stop to the fuselage, and then riveted the F-781 plate to the forward spar of the vertical stabilizer.  Fortunately, all of these rivets could be reached with my pneumatic squeezer.  Once the elevator stop was in place, I checked to make sure it was the first thing the elevator horns hit.  While the elevator horns hit both the up and down stops before contacting anything else, I still need to check the amount of elevator deflection and possible shorten the stops if the deflection isn’t adequate.

Finally, I re-installed the vertical stabilizer.  Right now, the vertical stabilizer attaches with 6 bolts.  Two bolts are through the aft spar and the up elevator stop, and four bolts are through the front spars of both the horizontal and vertical stabilizers.  Now, all that is left for the vertical stabilizer installation is to drill the lower portion of the rear spar to the aft bulkhead of the fuselage and the tail wheel mount.

The F-781 plate was riveted to the forward spar of the vertical stabilizer. Then, the stabilizer was mounted on the fuselage.

The up elevator stop was riveted and bolted to the fuselage and vertical stabilizer. There is a washer on the between the stop and the vertical stabilizer on the left side to help with the offset of the stabilizer. I do need a longer bolt on that side though.

Everything except the rudder!

Looking more and more like an airplane!

More Empennage Installation (4/19/14)

3.5 Hours –

Today, I continued working on the empennage installation.  However, before I could do any more work on the plane, I had to gather all the parts.  For the empennage, this meant climbing into the attic.  Normally, this is an easy task, but with a garage full of large airplane parts, lowering the attic ladder isn’t always possible without significant rearrangement.  Fortunately, I was able to push the tail of the fuselage far enough over for the ladder to come down.  Then, it was just a matter of handing the tail pieces down to my wife one at a time.  Surprisingly, these parts, which have been in the attic for years, had very little dust built-up on them, and absolutely no corrosion that I could see.

The first task was to install the elevators on the horizontal stabilizer and drill the elevator horns for the push rod bolt.  To do this, the horizontal stabilizer was placed upside down on my workbench.  The elevators were then installed with assembly pins and clamped in the “in-trail” position.  The elevator horns are not a matched set, so there is a little variance between parts.  Most builders do not have horns that are perfectly aligned.  Although my horns were close, the right horn is about 1/4″ aft of the left horn.  Once the aft horn is identified, it is drilled in the appropriate location with a #30 pilot hole.  Then, I made a spacer/drill guide for between the horns using a block of wood.  This spacer has a #30 hole drilled through it using the drill press to ensure that the hole is perpendicular to the block.  The spacer is then inserted between the horns and used to guide the drill for cutting the hole in the opposite elevator horn.  Once both horns have a pilot hole, the holes are enlarged for an AN3 bolt.

On the workbench, the elevators are temporarily installed on the horizontal stabilizer and clamped in the “in-trail” position.

The elevator horns aren’t a matched set, so one is usually aft of the other, and this must be accounted for when drilling the hole where the push-rod will attach. My right elevator horn is slightly aft (left in this picture since the whole assembly is upside down).

A wood block is used to make sure that the holes in the elevator horns are perfectly aligned. The wood block has a #30 hole through it that was made with the drill press to ensure straightness.

The aft (right) horn is drilled to #30 first. Then the block is used to align the drill for forward (left) horn. Once the pilot holes are drilled, the block is removed and the holes are enlarged for an AN3 bolt.

Next, the elevators were removed from the horizontal stabilizer so  I could move the parts to the fuselage.  Once the horizontal stabilizer was on the fuselage, the elevators were reattached, and I was able to bolt the push rod to both elevators.  With the push rod attached, I checked to make sure the elevators were aligned with each other and moved freely in both directions.  With the lightest touch, I could easily move the elevators, and there was no binding of any kind.  Needless to say, I had to play with elevators for a few minutes!

Once the elevator horns were drilled, the whole assembly was installed on the fuselage and the elevators were connect to the pushrod. Here they are, moving together, in the up position.

And, of course, here they are in the down position. Ignore my finger…without holding them, they want to go back to neutral or up.

Once I finished playing with the elevators, I moved on to the vertical stabilizer.  The first thing is to cut 5/8″ from the bottom of the forward spar of the vertical stabilizer.  I’m not sure why Van’s doesn’t have you do this before assembling the vertical stabilizer since it would be easier at that time, but it was still relatively easy to do this using my Dremel and cut-off disc.  Next, I clamped the F-781 attach plate to the forward spar of the horizontal stabilizer and then clamped the vertical stabilizer to the fuselage.  At this point, the vertical stabilizer has to be positioned so that it is exactly vertical and the leading edge is 1/4″ left of center (to offset left turning tendency).  I took some measurements and re-positioned the vertical stabilizer to where I think the fit is correct, but I want to take a break and re-measure before doing any actual drilling.  I’ll return to this tomorrow.

The vertical stabilizer is clamped to the horizontal stabilizer’s forward spar and to the rear bulkhead of the fuselage.

A closer view of how the vertical stabilizer is clamped to the horizontal stabilizer’s forward spar.

In the meantime, I started fabricating the F-712D up elevator stop.  This part is fashioned from some stock angle, and I managed to get the rough cuts done, but it still needs a lot of finishing work.  However, since this is the first part to get drilled to the vertical stabilizer, it will be at the top of my priority list.

The F-712D up elevator stop is the first part that gets attached to the vertical stabilizer. Here is the rough cut part…it still needs a lot of touching up before it will be ready to be installed.

Finally, one to show the FAA as proof that I’m the builder.

Left Elevator Tip Installed (3/30/10)

1.8 Hours –

The left elevator tip was installed in the same manner as the right tip. I thought this tip would go on in about half the time of the right one. However, it ended up only taking about 10 minutes less, but it was easier and looks slightly better.  At least I got smart this time and used a shop vac to suck away dust as I cut away the fiberglass flange with my Dremel.  Granted, I still wore a respirator and safety goggles while cutting.

A close up of one of the 1/8" ID rivet washers already glued to the tip. Next to it is a CS4-4 blind rivet

The left elevator tip is on, and there is a pile of shanks from the blind rivets to prove it. This one was easier than the right and it looks a tiny bit better.

Right Elevator Tip Installed (3/28/10)

2.0 Hours –

With the wing kit on order and the wing stands essentially done, I have nothing that I can do on the airplane except work on the fiberglass empennage tips.  I was going to leave these parts off until just before the empennage components are attached to the fuselage, however, I really enjoy working on the plane and do not want to sit idle for another month and a half while waiting for the wing kit to arrive.  With this in mind, I decided to start working on the tips.

Some people just rivet the tips on and call it good, others rivet them on and then glass over the seam so that there is a perfectly smooth transition from aluminum to fiberglass.  For now, I’m just going to rivet them on.  After seeing how they look, I’ll decide if I want to fill them.  the nice thing is that I could fill them at anytime in the future…even after flying.

Starting with the right elevator, I quickly saw that the flange on the tips was too long and would need to be trimmed.  Also, the flange on the forward end of the tip must be removed to compensate for the location of the counterweight.

After carefully measuring and marking the tip flange, I proceeded to remove the excess material using my Dremel with a cutoff wheel.  Cutting the fiberglass generates a lot of dust.  After making a small cut, I decided to put my respirator on.  Unfortunately, the respirator doesn’t prevent the dust from getting all over me and everything else in the garage.  Oh, and that dust can make you itch too!

The flanges on the elevator tips are too long as they come from the factory. Almost 1/4" has to be trimmed off.

A bit of the forward flange also has to be removed in order to allow for the counterweight.

The right elevator tip is cut and ready for an initial fitting.

Once the flange was trimmed, I did a test fit.  A little more sanding and the fit looked good.  I started to drill the tip to the elevator using a #40 drill.  The elevator is pre-punched but the tip isn’t.  I would drill one hole, cleco the tip to the elevator, adjust the fit, and drill the next hole.  Once all the holes were drilled to #40, I enlarged them to #30 in order to accept the CS4-4 blind rivets.

The initial fit looks good...time to drill.Another view of the initial fit.

Another view of the initial fit.

After drilling and deburring, I dimpled the holes in the elevator using my pneumatic squeezer.  The tip, however, must be countersunk.  Since fiberglass is abrasive, and I’ve been told it will ruin a countersink bit, I decided to try making the countersinks with a conical grinding tool attached to my Dremel.  Surprisingly, this seemed to work well…at least well enough to justify not buying another countersink bit specifically for fiberglass work.

The tips are attached to the empennage using CS4-4 blind rivets.  Van’s instructs you to attach the tip directly to the elevator.  However, many builders elect to bond a strip of aluminum to the inside of the tip along the rivet line.  The aluminum adds strength and gives the rivet something a bit firmer to grip.  I elected to use another method…aluminum rivet washers.  These washers have a perfect 1/8” inner diameter and serve the same purpose as an aluminum backing strip.  However, rather than placing a strip along the entire length of the tip, the rivets are simply bonded to each hole with some E6000 adhesive.  This is simple and it should save some weight in the overall aircraft (at least a few ounces).

Some people rivet the tips directly on, others glue on strips of aluminum backing, I chose to use aluminum rivet washer...it might save a few ounces of overall weight.

The rivet washers are glued on and temporarily held with clecos until they are ready to be riveted.

I used E6000 glue for the washers since it was recommended by another builder.

Once the glue had some time to set, I went ahead and riveted the tip in place on the elevator.  Overall, the fit is good, but there is some waviness/gaps in the joint.  I think this is probably unavoidable, and, for now, I’m going to plan on leaving it this way since it is very minor.  If, further down the road, I decide to paint the plane, I’ll probably glass the joint over at that point.

The right elevator tip is attached with CS4-4 blind rivets.

The control surfaces of the RV are balanced, meaning they have a counterweight attached to them.  I believe this is done to reduce flutter and also ease the amount of force needed to move the stick in flight. To my surprise, the right elevator is almost perfectly balanced as it is now.  The counterweight is only slightly heavy which is perfect in the event that I decide to paint it (the paint adds significant weight to the control surfaces and the overall airplane).

The right elevator is almost perfectly balanced. I'm only holding the two rod end bearings with my fingertips.

Elevator Horns Drilled to Center Bearing (3/13/10)

1.0 Hours –

With so little left to do on the empennage, I haven’t been spending much time in the garage lately.  However, today I decided to finish fitting the elevators to the horizontal stabilizer.

This was another step that turned out to be simpler than I expected.  Basically, all I had to do was attach an elevator, clamp the elevator to the horizontal stabilizer so that it is “in trail”, insert my drill bushing into the center bearing, and drill a #40 hole in the elevator horn.  I started with the left elevator and then did the right.

Clamps held the elevator "in trail" while I drilled the elevator horn.

To drill the elevator horn, a bushing was inserted into the center bearing.

Once both elevator horns were drilled, I had to enlarge the initial hole from a #40 to 1/4”.  To do this, I just stepped up drill bit sizes until I was at 1/4”.  I could have used my unibit for this, but I’ve found that it chatters too much and it is easy to make the hole uneven or too large.  Since this is a crucial attachment point, I didn’t want to risk it.

Once the initial hole was drilled, I enlarged it to 1/4" by gradually increasing the bit size.

After both holes were enlarged, I reattached both elevators to the horizontal stabilizer and checked that the elevators moved freely, at all hinge points, through the entire range of motion.  Everything looked great!

Both elevators are attached at all three points and moving freely through their entire range of motion.

With the elevators done, the empennage is complete minus the fiberglass tips.  My wings are scheduled to be shipped the week of May 17th, so we’ll see if I last that long or get bored and go buy myself some West System epoxy for attaching the tips.

Finished Elevator Leading Edges (3/4/10)

1.5 Hours –

Maybe the third time is the charm.  Rolling the right elevator’s leading edge seemed to go much easier than both the rudder and the left elevator.  However, there’s still got to be a better way to do this…or at least some more tricks!

The left elevator’s leading edge was already rolled, so I started the evening by drilling and riveting it.  Pop rivets are used here and setting them was a non-issue.  If I ever build an RV-12, which uses mostly pop rivets instead of solid, I would definitely want to get a pneumatic pop rivet puller.

The leading edges of both elevators have been rolled, drilled and riveted. The left elevator is pictured here.

Once the left elevator was done, I repeated everything on the right.  This time, I rolled the top skin first and the bottom skin second.  Since the second skin always has to be rolled under the first skin to get the correct bend, I figured this would save me the hassle of pulling the top skin back out after the bends were complete.  The only area that I had trouble on the right elevator was the short, outer section.  This spot is only about 5 inches long and the counterweight assembly blocks your access to one side.  Since I could only grip the dowel with one vise-group, I was having trouble getting a nice even bend.  Some waviness resulted in the final product, but no big deal in my opinion.

Finally, I was able to pull my homemade rod-end bearing installation tool out of the toolbox for the first time.  When installing the rod-end bearings, a nut, called a jam nut, goes on the rod-end bearing first and then the assembly is screwed into a nutplate.  Once the desired depth is reached, the jam nut can be screwed down onto the spar.  At least this is how I think it is done, but I can’t really figure out the purpose of the jam nut.  I guess it is anti-rotational, but won’t the brackets on the horizontal stabilizer also immobilize the bearing and prevent it from turning either direction?  I guess a search of vansairforce.net is in order.

I was finally able to use my homemade rod-end bearing installation tool.

An installed rod-end bearing in the right elevator.

All of the empennage structures are now complete.  All that is left is some final work to fit the elevators to the horizontal stabilizer and installation of the fiberglass tips (which may wait until the airplane is almost done).

The main structures of the empennage are done. All that remains is some finishing work and fiberglass.

Left Elevator Leading Edge Rolled (3/2/10)

0.8 Hours –

I got home from work today and was planning to start a load of laundry and then relax in front of the TV for a bit.  However, when I went into the garage with my laundry, the airplane started calling to me (this is not an uncommon experience).  So, I loaded the washer and proceeded to work on rolling the leading edges of the left elevator.

Rolling leading edges has definitely become my least favorite thing to do so far in the RV-7 build.  It is physically difficult to do and it is hard to get the right amount of bend in each half so that the holes line up without having to exert a great amount of force.  As with the rudder, I used Van’s dowel, duct tape, and vise grip method to bend the skin.  In summary, a length of 3/4″ dowel is duct taped to the edge of the skin.  Then, using two vise grips, the dowel is rotated, bending the skin along with it.  The bottom skin is fairly easy, but the top skin is a pain due to the bottom skin being in the way.

Eventually, I was able to place clecoes in all of the holes and it took less force to line up the skins compared to the rudder.  Maybe a few lessons were learned on the rudder, but I figure there are still many ways to make this easier.  Lucky for me, I have a second elevator to practice on.  However, it is going to have to wait for another day when my patience has returned.

The left elevator's leading edge has been bent and clecoed. This is easily my least favorite thing to do so far in the build!

More Trim Work (3/1/10)

2.0 Hours –

The first thing I did today was drill a hole in the elevator spar for the trim servo wires to pass through.  According to the plans, the wires can share the hole that the servo’s jack screw occupies, but the jack screw is a threaded rod and, like many other builders, I could foresee this chaffing the servo wires eventually leading to a failure.  Instead, I drilled a  3/8″ hole through the spar at the location of the lightening hole on the control horn.  Once drilled, I smoothed the edges of the hole and inserted a grommet.  My eventual plan is to use a d-sub connector to link the servo wires to a five-wire, shielded cable running to the fuselage.  The d-sub will stay inside the elevator with the servo and only the cable will pass through the grommet and run to the panel.

Rather than having the servo wires share a hole with the jack screw, I drilled a second hole and inserted a grommet to protect the wires.

With the trim servo in the full down position, the jack screw extends almost an inch out of the elevator spar.

Next, I started fitting the trim push rod.  I was a bit stuck on this and had to post a question in the forums on VansAirForce.net.  As usual, I was given a quick and thorough explanation of how to measure and cut the rod.  First, I attached one clevis to the servo.  Then, I inserted the servo into the elevator and screwed the access panel on tight.  Using a drill battery, I ran the servo so that it would be fully retracted (trim tab full down).  I then screwed the push rod into the clevis on the servo and used it to measure the approximate length it needed to be in order to screw into the clevis on the trim tab while the tab was in the full down position.  Finally, I cut the rod with a hack saw.  After doing this twice, I finally had the rod to the appropriate length.  I’ll need to do some fine tuning later on, but for now we’ll call it good.

With the trim rod in place, I ran the servo both directions to check and see if any of the hardware was binding or rubbing on the elevator.  While there was no contact, it was extremely close.  To fix this, I did two things.  The first was to put a slight bend in the push rod.  The second was to file away some of the metal surrounding the opening where the rod/clevis protrudes.  Once I filed enough metal away, I had to do some finishing work to smooth the edges and I also gave everything another coat of primer for appearance sake only.

The elevator is upside down, but this is the full down position of the trim tab.

In order to make sure there was enough clearance, I had to put a slight bend in the push rod and file away some of the access opening.

The good news is that this should be the end of my trim tab battle.  At least until I’m almost ready fly!

Finishing the Left Elevator (2/27/10)

3.0 Hours –

After quickly squeezing the last of the rivets holding the left elevator skin to the skeleton, it was time to attach the forward trim tab hinge.  The goal here is to have the trailing edge of the elevator and trim tab in perfect alignment while minimizing the gap between the tab and elevator and also keeping the inside edges aligned.  It all sounds relatively simple, but it was a bit frustrating.

The left elevator is completely riveted except for the trim hinge attachment holes.

The frustration arises when you can’t find a good straight edge.  It continues when you get everything aligned, but can’t keep it aligned while trying to clamp it.  The frustration boils over when you have everything in place, managing to keep it place, but then can’t find a way to clamp it so that you can move your hands.

Finally, I managed a system where I weighed down the elevator so that the trailing edge was flat on my table.  I then used long, narrow diameter curtain rod to line up the trailing edges of the elevator and trim tab.  Finally, I placed one cleco clamp on the inside edge of the hinge and held the rest of the trim tab in place while I drilled the first hole.  Once drilled, a cleco was inserted into the hole and I moved on to the next hole using the same tedious method.  After drilling and clamping about four holes in this manner, I was happy with the alignment and started to move a little faster.  The end result was a trim tab and elevator in perfect alignment and a relatively small gap between the tab and elevator.

Aligning the trim tab for drilling the huge was a royal pain in the A$$!! I used a curtain rod for a straight edge to align the trailing edges.

With the hinge drilled, the tab moved well with no binding.

I'm satisfied with this small gab between the trim tab and elevator. It is straight and both the trailing and inside edges line up perfectly.

Next, the plans tell you to sight down the trailing edge of the elevator and trim tab one last time to make sure everything is straight.  If the tab is at all bowed, you should be able to twist it to take the bowing out.  Once everything is straight, you drill and cleco the three holes on the inside edge of the trim tab.  Once these are drilled and clamped/riveted, everything should be locked into place.

Apparently, this was supposed to be done before I riveted the aft portion of the hinge to the trim tab.  Fortunate for me, everything was perfectly straight and stayed that way after I drilled and riveted the inside three holes.

The inside end of the trim tab has three blind rivets that are the last to go in.

Finally, I prepped and primed the forward portion of the hinge before riveting it to the elevator.  The left elevator is now done except for drilling one hole for the trim servo cable and rolling the leading edge.  Despite the frustration, I’m happy with the way the trim tab turned out.  Some of the bends could be smoother and you can see dents caused by the rivet gun while trying to flatten the bend, but, no one is going to see these unless they are really looking.  To continue my mantra, I’m building a “go-plane” not a “show-plane.”

The trim tab is finally finished. The gap looks larger here because the tab is angled down slightly.

Final Assembly Started On Left Elevator (2/25/10)

2.0 Hours –

My replacement parts from Van’s arrived yesterday, but I didn’t make it into the garage as I was too busy watching the Olympics…men’s hockey to be specific.  Everything is looking good for a USA vs. Canada gold medal game!

When I finally made it into the garage tonight, I started by prepping the new E-606PP rear elevator spar.  Since the kits are pre-punched, getting everything to line up on the new part was simple.  I just had to drill the holes to size, then dimple or countersink them.  This time, I quadruple checked that I was countersinking the top flange instead of the bottom.  Of course, I thought I did this last time as well.  This time, I also kept the bad part on the table to make sure the new part was opposite.  Once everything was countersunk and dimpled, I primed it and moved on to elevator assembly while the primer dried.

My new E-606PP. This time, countersunk on the top side instead of dimpling like I did the first time around.

If the picture were better, you could see that I reversed the dimpling and countersinking from my first try (aka...dumb mistake).

The first thing I had to do was re-drill counterweight.  I marked the hole locations using the counterweight skin and then drilled the holes with my drill press.  I wasn’t sure how this would work since the counterweight skin was already dimpled.  Fortunately, everything lined up fine and I didn’t have to use the new counterweight skin I purchased.

Next, I checked the fit of the trim servo one more time before closing the elevator.  Any fixes would be easier to perform now while the inside of the elevator was still accessible.  Everything looked good as the servo and access panel easily fit into place.

I then placed some blue RTV at the aft end of the elevator stiffeners, slid the skeleton into place, clecoed the elevator together and started to squeeze rivets.  I made it through about 3/4 of the rivets on the top side of the elevator before deciding to call it quits for the night.  Before heading inside, I marked the top of the elevator over the rear spar “No Rivets.”  The trim hinge must be fitted here before riveting…let’s see if I remember to read this when the time comes or if I end up drilling out a bunch of rivets instead.

The new E-606PP rear spar in place on the left elevator.

I squeezed about 3/4 of the rivets on the top side of the elevator before calling it quits for the night.

The blue vinyl is a good place for temporary reminders. Hopefully, I'll read this at the appropriate time.