Rigging the ailerons

Posted on August 16, 2014 by dsetser

Next up on the list of things to be done is rigging the ailerons and aileron pushrods to the control sticks. There’s nothing too difficult here, but like a lot of other tasks at this stage, there’s a lot of tweaking and adjusting involved.

There are two pushrods for each aileron, one from the control stick to a bellcrank in the wing, and another from the bellcrank to the aileron itself. I had already adjusted both bellcrank-to-aileron pushrods when I built the wings, but I wanted to recheck them anyway. So I dug out the bellcrank jig and the fixtures I made to hold the ailerons in trail.

Here’s the fixture that establishes where the trailing edge of the aileron should be…it’s bolted to two tooling holes in the outboard wing rib –

And here’s a couple of pieces of wood I screwed together to hold the aileron itself in place on the fixture. You can see the two lines that define where the trailing edge should be…

Since I already had a pretty good idea that the outboard pushrods were correctly set, I just slipped the bellcrank alignment jig into place and verified that everything was still ok.

You can’t see the bellcrank jig very well, but it’s the silver piece of metal above the bellcrank itself. It’s placed over a pushrod bolt, and if the jig’s forward edge rests flush against the spar *and* the aileron is aligned in trail, everything is set – which it is here and in the opposite wing.

With the ailerons properly in trail, I clamped the control sticks in place so they were vertical (sorry, no pictures) and adjusted the long bellcrank-to-stick pushrods to the proper length. I then went back and torqued all the bellcrank bolts and nuts, as you can see from all the Torque-Seal in the picture.

It was kinda neat to move the control sticks and see the ailerons move…before the wings come off again I may have to throw a seat in the cockpit and play pilot for a little while!

Wing root fairings and flap rods

Posted on August 9, 2014 by dsetser

I have a whole laundry list of things that need to be done now that the wings are fitted.

First up was fitting the wing root fairings. Nothing too difficult here…the only trick is getting the fairing to conform to the wing leading edge curve enough to get all the holes aligned with those in the wing. A little hand shaping of that area solved the hole alignment problem.

I realized that I made a small mistake several years ago when I built the wings – I match-drilled and dimpled several of the wing skin/rib holes that should have been left undrilled for the fairing attach screws. Looks like I’ll have to drill them out to the right size (#19) and then re-dimple to accept a #8 screw. No big deal.

While I was at Oshkosh I bought these spiffy pre-drilled hex flap pushrods rods from Avery Tools. Drilling and tapping a piece of round tube stock for these pushrods per plans is a pain, so these Avery rods save a lot of time and effort…just screw in the rod ends, and you’re done. Cool.

Gotta do it right the first time…

Posted on August 3, 2014 by dsetser

Carrying on from my previous post – there’s one task that RV builders know has to be done right the first time, and that’s drilling the holes in the aft wing spar that set wing sweep and incidence. I’ve already covered all the measurements that verify the wings are in the right position and there’s good edge distance…now it’s time to drill.

Van’s has a good description of the process on their Construction FAQ page, so I won’t repeat their words here. I found a piece of scrap aluminum bar at a local metal dealer and cut pieces to make drill blocks for #30, 3/16″ and 9/32″ drill bits and one for a 0.311″ reamer – to enlarge the hole in stages. The 9/32″ drill seems like an odd choice, but the ideal use of a reamer is on a hole that’s about 1/32″ undersize – and 9/32″ is just that for the 0.311″ reamer.

The pucker factor was pretty damn high when drilling the #30 pilot holes, but they came out fine –

I then worked up to 3/16″, 9/32″ and 0.311″ and ended up with good holes in each rear spar.

Enlarging to 3/16″ wasn’t too tough, but I was concerned about making sure the 9/32″ drill block was centered – don’t want to eat into the edge distance margin. But then I had a brainwave – insert a long 3/16″ pin punch through the 9/32″ drill block and on into the 3/16″ pilot hole, and continue until the punch’s shank hits the side of the drill block hole, centering it on the 3/16″ hole. Clamp the drill block in place, and voila – the block is centered and ready to use. Here’s the right side –

Here’s the right rear spar, without an AN5 bolt in place…

The drill block process worked really well – finishing the holes with a 0.311″ meant a nice, snug fit for an AN5 bolt – they went in with only a little finger pressure. These bolts are supposed to be be a nominal 5/16″ diameter, but they often run undersize. Had I used a 5/16″ reamer, the bolt fit would have been ok, but probably sloppier than I’d want in this application.

So…the rear spars are drilled and it’s a huge relief. I have a backlog of things that need to be done to the wings, like rigging the ailerons and flaps, and it’s time to make some serious forward progress.

Sprouting wings

Posted on July 20, 2014 by dsetser

Food can be effective bribe. Last weekend I bribed Ellen and Whitney, and RV-7 friends Andy Olech and Allison Bailey, with lunch at the Midfield Cafe to help install the wings for the first time. Thanks Andy and Allison, we appreciate you flying up from Hartford and spending the day with us!

And as always, thanks to my family – Ellen and Whits, I couldn’t do any of this without you !

This is one of those times in the project when a lot of past effort to maintain tight tolerances really pays off. Every RV slow-builder stresses about making sure the front and rear spar bulkhead halves in the fuselage are spaced 1.438″ apart as required by the plans. With the help of a little Boelube, the spar ends slid right into the fuselage. Cool.

With Andy, Allison, Ellen and Whitney adjusting wing position, I inserted a couple of taper pins into bolt holes for each wing. Van’s calls for four pins, so before I made any final measurements and drilled any holes, I borrowed some long, custom-made stainless steel taper pins to augment the four pins I made from hardware-store bolts.

Thanks to Rich Mileika for making those really nice stainless steel taper pins, to John Sannizzaro and Bill Higgins for flying up to Nashua yesterday and helping me get the last 3-4 taper pins in so that the wings are secure, and last but certainly not least, thanks to Bob Weldon and his daughter Emma for muscle power and precision plumb bob stabilization <g>.

With the wings temporarily installed, I made sure the fuselage was level laterally and longitudinally. The plans call for measuring longitudinal level on the longerons at the cockpit, but these almost always have some residual twist from the bending process that makes it hard to get a good level measurement.

So, I just moved the levels back a few feet to a straight portion of the longerons. I had to adjust the cradle a little to get everything spot on, no big deal.

According to the Van’s FAQ on wing incidence and sweep, the next measurement is from reference points on each wingtip to a common point on the aft fuselage. My measurements were the same to within 1/32″…cool again.

I then dropped plumb bobs from the wing leading edges – one inboard and one outboard on each wing panel, and laid out a reference line between the outboard plumb bobs to serve as a reference for double-checking sweep. Measuring the distance from the inboard plumb bobs to the reference line, I found that each wing had only 7/32″ of sweep, well within the 1/2″ tolerance that Van’s suggests.

The next measurements check wing angle of incidence. This requires making a simple tool – a carpenter’s level or metal channel with a 3″ spacer on one end. The flat end is placed on the wing skin above the main spar web, and the spacer sits on the skin above the aft spar web. When a level placed on the tool reads zero, the wing has a 1 degree angle of incidence.

The pic above shows the left wing incidence is right on the money. The right wing was the same.

Just for a goof, I checked the angle of incidence at each wingtip…every measurement was within 0.1 degree. This is a real tribute to the quality of Van’s prepunched kits; with reasonable effort, it’s possible to build a nice, straight airplane.

I also test-fitted the flaps to make sure the inboard flap skins fit nicely against the fuselage…

…and it looks like they do.

The last and most critical measurements are edge distance on the rear spar for the hole that accommodates a single attach bolt. I laid out lines on the fuselage and wing spar attachments that represent minimum edge distance from the hole center. As long as there’s distance between the vertical line on the wing spar fitting and the vertical line on the fuselage fitting, there’s sufficient edge distance for a 5/16″ bolt hole.

The right wing looks good…

…and so does the left wing.

I’m not in a rush to drill these holes. They’re one of the few gotta-do-it-right-the-first-time things on the project, and I plan to sneak up on them one step at a time.

More to follow…

Rudder cables and ELT mounts

Posted on July 12, 2014 by dsetser

Over the course of this week I’ve been at the hangar a few times to take care of random stuff prior to mounting the wings.

Before we moved the fuse to the hangar, I installed and secured the rudder/tailwheel steering cables to the tailcone. It would have been good to check the plans and see which end of the cables attach to the rudder control horn (the two ends of the cable aren’t the same), but I neglected to do that. Compounding that mistake, I had already fished the cables through several holes in the tailcone and aft fuse and installed snap-in plastic grommets in those holes that make it impossible to remove the rudder cable once they’re installed. As an extra bonus, the grommets can be installed with access to one side of a hole, but access to both sides of the hole is required to remove them – which is a problem in several places in the tailcone and baggage area where panels are already riveted in place that limit access. D’oh!

Other builders have made this mistake and wound up drilling out rivets and removing panels to get at the grommets, but I was determined not to do that. So…I went on a trek to Home Depot (there’s one about five minutes from the hangar – bonus!) and bought a small propane torch and an X-Acto knife. A red-hot knife slices through plastic pretty easily, and working from one side of the hole, it’s not too hard to slice out the clips that hold the grommets in place. After an hour of heating and cutting, the grommets and the rudder cables were out. 30 minutes later, the rudder cables were installed the right way.

I also started working on the Emergency Locator Transmitter (ELT) mount. Over the last several months I’ve been working out where to install the ELT and have never been very happy with a lot of the options I’ve seen, including Van’s own ELT/strobe mounting plate which seems far too flexible to ensure that the ELT will work when it’s supposed to. Many RV builders regard the ELT as a bureaucratic nuisance and don’t care how it’s installed. They’re certainly free to do as they see fit, but if the device has to be in the airplane, I want it to work as it’s designed to.

My friend Andy mounted his ELT on the horizontal bellcrank rib, which seems like a good place for both longitudinal strength and access for installation, testing and battery changes. The only downside is that the rib doesn’t have a lot of lateral stiffness, and theoretically the ELT mounting surface should withstand a 100-pound pull in any direction without deflecting more than 0.1 inch. I came up withe the idea of fabricating an L-shaped reinforcement plate to provides extra stiffness, and had my fellow FAA DER Tom – who’s a structures engineer – run the numbers to make sure my design would be strong enough while not impacting the existing structure.

It turns out from Tom’s analysis that a piece of 0.040″ 7075-T6 aluminum sheet, bent into the required L-shape, will do the job nicely. It will be held in place on the vertical flange with ELT mounting bolts and the rivets which also attach the bellcrank stiffener angle, and on the horizontal flange with some AN426-3 rivets. Easy peasy! The only downside is that my candy-ass little Harbor Freight bending brake won’t handle 0.040″ 7075 sheet, so I’m gonna have to find someone with the appropriate tools to make the bend. Stay tuned…

More wing mating prep

Posted on July 11, 2014 by dsetser

With the the shop rearranged, there are a few prep things that need to be done before the wings can be fitted. First up is reinstalling the control stick mount assembly so the aileron pushrods can attached and rigged. The assembly was initially drilled to the F-704 bulkhead way back when I started the fuse a few years ago.

There are a lot of bolts and spacers that must be assembled in order so that there’s no sideload on the bearings when the bolts are tightened.

There are a couple of small washers that go on either side of the bolts that attach the control sticks, aileron pushrods and a connecting rod that makes sure the sticks move together.

These washers are a pain to maneuver without help, so I broke out the Avery washer wrenches…they did the trick.

The very last bolts to be installed were the ones that that hold the sticks to the mounts and allow them to move laterally. Because this is a rotating joint, normal Nylok self-locking nuts can’t be used – the castle nuts only get torqued enough to allow a cotter pin to be installed. I won’t do that until I’m ready to permanently install the control sticks.

On the other hand, they look so good that I might just leave them in!

Prepping for wing installation

Posted on June 16, 2014 by dsetser

My hangar mates won’t be flying the Archer for awhile, so we’re taking the opportunity to rearrange the hangar in preparation for fitting the wings. The fuselage gets moved to the front, so there’s plenty of work space.

I did some cipherin’ on my cheapo CAD program and the drawings say we should have enough space to get the wings on and still be able to do work around the fuse.

And now it’s back to fun with moving. Only two weeks to go ’til closing…

Bend, fit, repeat

Posted on May 26, 2014 by dsetser

One of the least enjoyable and most time-consuming parts of this project is bending fuel line tubing. With the fuse interior painted it’s time to install interior fuel vent and feed lines, and that means making a lot of tubing bends.

The fuel vent lines are (I hope) the hardest to form. They connect the vent fittings I fabricated a couple of days ago to their respective bulkhead fittings on each side of the fuselage, where an additional external line will connect with vent lines installed in each tank. They’re formed in a U-shape so that fuel won’t siphon out of the tanks. And it’s the U-shape that makes them hard to form.

I didn’t take any pictures of forming the complex bend at the lower left but it was a pain in the tuchas, and took three attempts to get it right. After that end of the tube was complete, it was a matter of figuring out where the next bend should be, making it, fitting it to the fuselage and making adjustments, then moving on to the next bend. It took a few hours, but the end result was good…

And here it is, installed in the fuselage. The fittings still need to be torqued, but it’s in the fuselage to stay…

I hope the right vent line won’t take so long…

Band-Aid? I don’t need no stinkin’ Band-Aid!

Posted on May 23, 2014 by dsetser

I spent most of the day at the hangar, and realized after I cut myself that one thing I forgot to bring from the house was some bandaids. But I have plenty of blue painter’s tape and lots of paper shop towels…

And this is what I cut myself on – a jury-rigged low-profile nut driver, made by grinding down a random 3/8″ driver I found in the tool box…

And why would I need a low-profile nut driver? I knew you’d want to know…

See that AN365 nut in the bottom center of the picture? There’s not enough space to get a regular socket on it, hence the ground-down nut driver. Worked great, if I do say so myself…and I do.

Next to it is an AN bulkhead elbow fitting for the left fuel tank vent line. I spent most of the day getting fittings prepped for the vent lines, including making the vents themselves out of other AN fittings –

These are relatively straightforward to make from standard bulkhead fittings, I just wrapped the not-to-be-modified ends with duct tape and chucked them in the drill press. The portion that’s bright metal in the picture originally had threads, but I removed them with a vixen file while the drill press spun the fitting around (thanks for the idea, Mike!). I cut the finished ends to a 45-degree angle with the band saw, and cleaned them up with sandpaper and scotchbrite.

Vans recommends that the scarfed ends be protected by a screen to keep bugs and other stuff from blocking the fuel vents, so I bought some window screen patches from Home Despot and broke out the JB Weld epoxy…

After the JB Weld cures – hopefully by tomorrow – I’ll trim away the excess screen and install the vents in the lower fuselage.

A mostly-successful painting day

Posted on May 18, 2014 by dsetser

I’ve been waiting to paint the interior until the fuse is in the hangar and I have a little space to work. My hangar partners had their Archer outside for awhile, so now was a good time for painting.

I spent a lot of time masking and prepping the interior, then thinned some JetFlex WR interior paint and started shooting. I can’t say I’m 100 percent happy with how the JetFlex came out – there are some areas where the finish is a little rough – but it’s not bad enough to justify stripping it and reshooting.

Once done, I pulled the fuse outside and set our seats and shoulder harnesses in the cockpit to get an idea of how the colors match in bright light. Everything looks good.

The Mighty RV

Building, flying and maintaining a Vans RV-7 custom-built airplane in New England

Category Archives: Fuselage