Finished aileron attach bracket prep

04 Jul 2006: Yours truly, 2 hours. I had a little time before tonight's festivities to swing by the garage and finish the prep work on the aileron brackets. We are going to anodize these too. The thinking here is that, just like the pushrod tubes, once these are riveted together, there is no possibility to inspect for corrosion inside. Paint would of course be cheaper, but we think this will be a lot better, and won't cost too much. We've got a lot of little parts that are lying around waiting for paint, and we're going to take it all to the plating shop. Soon, we're going to have to start painting, or these plating expenses will get out of hand!

Brake pedal, flap brace, aileron mount and fairing prep

29 June 2006: two of us, 4 hours each. Lots of little jobs tonight. We trimmed the brake pedal side angle brackets to fit into the rudder pedal weldments. We trimmed the flap braces to clear the rear spar reinforcement. We trial-fitted the aileron attach brackets and trial fit the aileron gap fairing. With the aileron brackets cleco'ed together, we match-drilled and reamed the rivet holes, disassembled the parts, buffed the edges, and deburred the holes. Didn't finish them all - 2 to go.

Pushrod completion, etc.

27 Jun 2006: all of us, 3 hours each. Tonight we completed the aileron and elevator pushrods by assembling and riveting the now-anodized aluminum tubes to the rod ends. The rivet holes were fully prepped prior to anodizing. We also fitted the control stick assembly to its mounts in the fuselage, and prepared the nut that attaches the fuel pickup tube to the anti-rotation bracket for safety-wiring, per Van's Service Bulletin.

Fuel tank cover plate, more brake pedal prep

20 Jun 2006: Two of us, 4 hours each. Tonight we riveted the nutplates and the anti-rotation bracket on to the tank cover plate, and sealed all the rivet holes and seams with Tite Seal, which is what we plan to use for the gasket that goes between the cover and the tank bulkhead. This was recommended to us over Pro Seal as being just as secure against leaks, and much easier to remove if that is ever necessary. It's not ideal for sealing up rivets like we did tonight, because it doesn't set fully like ProSeal does. We decided to give it a try anyway, since we had it handy and didn't have any ProSeal yet. If it fails the leak test, we can always re-do it with ProSeal. (Peek ahead: it passed the leak test).

We also did more prep work on the brake pedals: countersinking for the rivets that will attach the side angles, and deburring the rivet holes and, filing and sanding the larger lightening holes. A certain amount of grinding was also necessary to get everything to fit. We've talked ourselves into anodizing the brake pedals rather than painting them. To match the brake master cylinder assemblies, which mount right next to them, we're going to use a gold-tinted anodize. These will truly be "gold-plated" brake pedals! (I would say in hindsight that this was more expensive that I'd have liked, and unnecessary. Plus, we should have been more careful with the sandpaper, as on close inspection, the roughness from the sanding shows right through the plating.)

Brake pedals, fuel sender resistance check

15 June 2006: two of 4 hours, one came late and put in an hour. We worked some more on the brake/rudder pedal assembly tonight, getting everything fit together and match-drilled. We also measured and recorded the fuel sensor resistance levels in "full" and "empty" positions.

Roll Servo, etc.

13 June 2006: two of us, 4 hours each. Having received the roll servo from Tru Trak, we went ahead and test fit it to the spar. Tru Trak supplies a very nice mounting kit for the RV-7. The kit replaces one of the bellcrank mounting angles with a somewhat larger one that holds the servo. The servo is then attached to the bellcrank with a little pushrod, which is supplied.



The kit comes with professional drawings and mounting hardware, so there is very little to do except position and drill a hole in the bellcrank web to attach the pushrod. The only minor difficulty is that TruTrak's drawings don't show the mounting hardware. Naturally, the three of us each had a different view about how the hardware should be utilized! It's all pretty obvious, except the washer placement. A phone call to Tru Trak eventually cleared this up, once we found the right person to ask. The summary answer is that the large washers should be used to contain the rod end bearings if for some reason the bearing should ever break free of its enclosure. Once you have that clue, the rest is pretty obvious.

Other items for this evening: we reamed the holes in the bellcranks and fuel cover nutplates, and fabricated the angles that attach to the sides of the brake pedals, and hold the mounting hardware that attaches the pedals to the steel rudder pedal weldment.

More controls

01 Jun 2006: two of us, 3 hours each. Tonight we finished threading the flap pushrods, and fabricated and fit the aileron bellcrank spacers (W-929). With all the parts finally in hand, we test-fit the bellcranks to the spar. We also found all the parts we'll need to start working on the rudder and brake assembly.

Controls work

30 May 2006: all of us, 5 hours each. This was a busy night. We ground all four of the brass bushings (two for the aileron bellcranks, and two for the control sticks) to the specified clearances on the bellcranks. We cut to length and fitted the larger of the two elevator pushrods. We match-drilled the holes for the rivets that attach the rod ends to all three of pushrods we've made so far. We cut to length and tapped and threaded the tubes for the flap pushrods. All of these aluminum tubes will be annodized, as described in a previous post. We also inventoried all the blind ("Pop") rivets.

Tank work

25 May 2006: all of us, 4 hours each. Another of our guiding principles is to equip this plane for sustained inverted flight. This requires replacing the standard fixed fuel pickup with a flop tube in at least one of the tanks. With the Quickbuild, you get fully completed and pressure-tested fuel tanks. So, we had some hand-wringing about tearing into a perfectly good tank, but we are sticking to our plan. Tonight, we removed the right tank to begin the modification process. The idea is the right tank will be the "right tank" for aerobatics.

Also, we didn't like the edge clearance of the hole on the anti-rotation bracker made according to Van's drawing, so tonight we made another one with the hold repositioned slightly. This one looks better. Once this was all done, we took another look at the smaller-sized drawing update shipped with our kit, and realized that Van's has now provided a ready-made anti-rotation bracket with the kit! But after all this, we going to use the one that we made!!

We also did some filing on the aileron bellcranks to get the brass bushings to fit inside.

Left Fuel Pickup, Inventory

23 May 2006: all of us, 4 hours each. Lesson learned from last time, we started doing a detailed inventory on all the small bags of parts. Also, started on the anti-rotation bracket for the left fuel pickup, and completed countersinking for the nutplates in the cover.

Aileron Bellcrank and Fuel Tank Pickup & Sender

19 May 2006: 2 of us, 3 hours each. Tonight we fitted the aileron bellcranks and the fuel pickup and fuel sender for the left tank. We spent a lot of time looking for the brass bushing around which the bellcrank rotates. Later, we gave up and called Van's. Turns out it was in one of the small brown paper bags filled mostly with rivets, screws, nutplates, etc. that we hadn't inventoried yet.

Aileron Pushrod Fabrication

10 May 2006, 2 of us, 3 hours each.



Tonight we started fabricating the aileron pushrods. We cut the raw aluminum tubes to length using a pipe cutter, which worked pretty well, except that it rolled the edge of the tube in where the blade rolled around it. This caused an interference with the rod end, and it took a fair bit of filing to open the end of the tube enough to slip the rod end into it.

In the next few days, we debated a bit how to reliably prime the interior of these tubes. Once the rod ends have been riveted in, there is no practical corrosion inspection of the interior of the tube possible. Obviously, a fatigue failure of the tube would not result in a good day. A friend who is building a Long EZ suggested annodizing the pushrods, and pointed us to a shop he has used, Almag Plating Corporation in south Baltimore. This seemed like the perfect solution. We decided to go ahead and fabricate the elevator pushrods also, and get the lot annodized together. We ended up using a clear sulfuric anodize with hot water seal, which cost $75.00 for the whole lot. It would have been cheaper, but the rods were so long, the guys at Almag had to do a special job just for this.

The photo here was taken a couple weeks later, after the parts were back from plating.

Panel Ideas

One of our guiding principles in this project is to have a modern, all-electric avionics system. We have found Bob Nuckols' Aeroelectric Connection to be a pretty good source of information for home-builders on this topic: www.aeroelectric.com. We've also found some interesting discussions on the Matronics's site: http://www.matronics.com/digest/.





Early on, we decided that since a lot of our flying would be done with two of us sharing the duties, we wanted the right and left seats to be "created equal" as much as possible. This led us to the idea of using an LCD screen on each side that could be swapped between engine info and primary flight instruments, depending on who is currently flying. Radios, moving maps, and backup flight instruments will then fill out the middle of the panel. Given the limited relatively small size of the RV-7 panel, we quickly decided that we needed to go with 2-1/4" backup flight instruments, rather than 3-1/8". This would turn out to be a somewhat limiting choice, but we can live with it.

Although it will be some time before we buy the avionics, we plan to install the autopilot servos while we still have easy access. After a fair bit of trolling around the web and talking to lots of fellow home-builders, we decided that TruTrak, www.trutrakflightsystems.com, was the clear choice for us. Besides hearing lots of good things about the design, performance, and reliability of TruTrak's servos and controllers, we really liked the option of getting a single instrument that served as both a backup attitude reference and the autopilot controller. Unfortunately, our decision to stick with the 2-1/4" instruments means we will be limited to the single-axis Pictorial Pilot, rather than than the two-axis ADI Pilot product. I talked to the designer of this device at Oshkosh, and he told me that he really tried to fit the ADI Pilot into a 2-1/4" form factor, and it just didn't work. This doesn't mean that we won't have a pitch autopilot however. We plan to use the Altrak VS product, which provides a simple altitude and vertical speed select functionality. One other limitation of combining the autopilot with the backup instrument is that both the Pictorial Pilot and the ADI Pilot use the analog Digitrak controller, rather than the digital Digiflite controller. The advantage of going digital would be that it can accept digitial steering over an ARINC 429 bus. However, it also costs a fair bit more, and we are already over budget on this panel!





More web trolling, email traffic with vendors, and visits with the vendors at Oshkosh has led us to conclude that, as of today, Grand Rapids, www.grtavionics.com, has the system closest to what we would have designed ourselves. Although the screen resolution is not as good as the competition, and their use of Windows CE for the display unit operating system disappoints us, they seem to have the best AHRS (attitude heading and reference system) design, and this is the guts of the EFIS. Also, they have a tight integration with the TruTrak autopilot that we like, and can drive it to follow a heading reference from the nav radios, and their bus concept gives us enough flexibility to achieve our goals, although we are afraid we will be close to maxing it out. An important consideration for us is also their claim that they will be offering a WAAS, IFR-certified GPS option. They already have a VFR version. If this comes to pass, it may put us over the top on the decision to go with GRT, since it will save us a ton of money vs. buying something like the Garmin GNS 430.

Finally, we are leaning toward the Garmin GTX327 transponder and Garmin SL30 nav/comm, since they are priced competitively and seem to offer better technology than the competition. Still TBD are (1) do we really need an audio panel, or could we live with just an intercom and marker beacon receiver and (2) do we need a backup nav/comm radio? There are a couple topics in play on the backup nav/comm that need to be resolved. One is whether or not GRT comes out with the IFR GPS option. If they don't, and we get a separate IFR GPS anyway, we will likely make it a GPS/nav/comm unit like the GNS 430. Since this unit effectively has the SL30 built in, we could drop the separate SL30 in this case, if we were OK using handheld nav/comm and handheld GPS as a backup. Besides cost, the other issue with backup nav/comm is antenna placement. We are hoping to use the Bob Archer antennas (http://home.hiwaay.net/~sbuc/journal/bob_archer.htm) that mount inside the wingtips, to try and keep the drag down as much as possible. Unfortunately, Archer's vertically-polarized tip antenna won't fit in the new RV-7 vertical-stabilizer tip, so we are going to see how using one of his horizontally-polarized antennas in the wingtip works for comm. If the gain is adequate, we will see about taking the 3 dB hit for a splitter so that a backup comm radio could share the antenna. We'll try this out with the handheld first, then look into adding a comm-only backup comm radio to the panel. Note that we don't have this issue for nav, since we only plan to have one VHF nav radio, the other nav being provided by a precision-approach-certified WAAS IFR GPS.

The last two images here, which I made using epanelbuilder, www.epanelbuilder.com, show some variants on these options. You have to use screen capture to get the images off the webpage, unless you pay them!

Wing Cradle Completion

29 Apr 2006, about 3 hours (forgot to write it down!)




We completed the wing cradle today, and it sure cleared up a lot space in the garage! I think we did some more inventory, starting to break down the subkits, but no one remembered to write anything in the log that day, so all we have is the photos. So far, this is the one and only time we forget to write something up in the log.

Inventory, Bent Panels Found

27 Apr 2006: 2 of us, 3 hours each.


Today we did a detailed inventory of all but the numerous subkits. Everything was there, but we did find two panels that appear to have been slightly bent in the shipment. These are the left and right F-7105B outboard sub-panels. These parts were in the large cardboard box, lying together on top of several other parts.

As you can see from the photos, there is about a 1" deflection, uniformly across them both. This corresponds to the way they were laying across the material that was underlying them in the box. Since there is no "fence" along the edge with the largest bend, we can't see how we could flute them to restore their flatness. Drawing 24 shows a slight bend across the bottom of these panels in Section A-A, but it appears to be opposite to the way the F-7105B right subpanel that we received is bent.

We did contact Van's about this, and sent them photos, and their response was "the[y] will be just fine. When you get to the point that you install them you will make a bend across the bottom and that will help straiten[sic] them out." While we agreed that this would probably work, we would have preferred to have Van's send us a set that were straight.

QB Kit Arrival!

23 Apr 2006: 2 of us, 2 hours each.



We got a surprise phone call from Partain's that they were only a few hours away, and would be delivering the kit today! We had planned to finish the wing cradle, but instead spent today unloading and unpacking. It was really easy: the wings were strapped to the sides of the trailer, and the fuselage was in a roller cart that we could roll right into the garage. It only took two of us to lift it off the cart, with a third steadying the tail. The wings could easily be carried off the truck by two, each holding one end of the main spar. Too bad we didn't get that cradle finished in time!

The stuff wrapped in blue film is the ailerons and flaps.

Preparations for QB Kit arrival

20 Apr 2006: 2 of us, 3 hours each. Due to various logistics, we didn't get started right away after coming back from the Builder Assist, but after several weeks, we finally got the Quick-Build kit ordered, and reconvened to start preparing for the kit's arrival: cleaning out the garage, and starting on a cradle to hold the wings. We decided to use Partain Transport to deliver the kit. The thinking was that this would save us having to get a delivery truck down the driveway, unload a large crate from off of a truck, and we'd save some money on the crating charge.

Builder Assist Program Day 4

09 Mar 2006: 5 hours each. Day 4 of the Builder Assist. Thanks to all our hard work the last 3 days, and the willingness of Jacob and Mike from Alexander Tech Center to stay late supervising us, we had only a few things to wrap up today. The elevators, rudder, and trim tab had been primed the previous night, so all we had to do was assemble them all back together, and do the riveting.

There were a couple of tricky spots for which we really benefited from the Builder Assist Program. One was rolling the leading edge of the elevators, for which once again, they had a handy stand that held the elevators in place while rolling. Here is Jacob from Alexander Tech Center demonstrating how to use the stand.




The other was riveting the trailing edge of the rudder while keeping it as straight as possible. On this last step in particular, we really benefited from Jacob's advice and instruction.

Builder Assist Program Day 3

08 Mar 2006: 10 hours each. This was Day 3 of the Builder Assist Program.






We completed the final assembly of the horizontal and vertical stabilizers.






They had a frame that was really handy for riveting on the horizontal stabilizer skins. It made it fairly easy to reach up inside the stab to buck the rivets.

Builder Assist Program Day 2

07 Mar 2006: 11 hours each. This was day 2 of the builder assist program. We completed the horizontal stabilizer pre-assembly, and the rudder pre-assembly. As before, this was more fluting, grinding, fitting, match-drilling, deburring, and dimpling.








Then, we marked everything using a blue sharpie, and disassembed it all for priming. Included in the price of the builder assist program is priming all the inside surfaces of the empennage with two-part epoxy primer. We hadn't really made a decision at that point on what we planned to do about priming the rest of the airplane, but considering the importance of the empennage to stability and control, the difficulty of ever getting back inside to prime it once it was closed out, and given that it was "paid for," we decided to take the weight hit and go with two-part epoxy.



While the primer was drying, we also started pre-assembly of the elevators and trim tab. This was a long day, but we were already starting to think about finishing in less than four days, so we pushed it. Having only one kit in the shop was really speeding things up!


Here is Mike from Alexander Tech Center showing us how to easily remove strips of the blue protective film using a blunt soldering gun, making it really easy to expose the rivet holes.

Builder Assist Program Day 1

06 Mar 2006: 10 hours each. This was day 1 of the Builder Assist Program. We elected to stay at the onsite dorms, and it was really great being able to stay so close to the shop. They are nothing fancy, but you don't have time for TV anyway! We lucked out, as there was only one other builder coming that week, and he cancelled at the last minute. So we had the whole facility to ourselves!

Day 1 consisted of a series of presentations in a classroom giving an overview of what we'd be doing, then we headed for ths shop. First, inventory.






The rest of the day we spent on pre-assembly, match-drilling, deburring, and dimpling. Two of worked the horizontal stabilizer, and one worked the vertical. It's important to "flute" the ribs, as the manufacturing process warps them. This is done using fluting pliars to flatten them out, as shown here.



Here are some more photos showing the spar and skin pre-assembly, and some trimming and grinding work. The little cylinders sticking out everywhere are clecos, which you insert into the rivet holes to hold the pieces in assembly.

What and Why

This blog is about three friends' experiences building a Van's RV-7A, one of the most popular kit-planes around today. The RV-7A is an all-aluminum, two-place, 200 mph, aerobatic, low-wing aircraft with a constant chord NACA 23013.5 airfoil section. We will probably build it with a 180 HP fuel-injected, four-cylinder, horizontally opposed, normally aspirated engine, with inverted fuel and oil systems. We are leaning towards a constant-speed, two-blade prop. We plan to have a modern, all-electric, glass-cockpit-type of panel, with a few "steam-gauge" backup instruments.

What motivated us to do this? One important reason is frustration with what we can afford through the certificated aircraft market. We hope to build the completed aircraft for around $100,000, which is certainly not cheap, but way less than even the closest thing available in in the certificated market. We like to think that each of us is paying about what we would for a sports car. Another reason is that we are all spacecraft engineers, who also love airplanes, and this project is giving us a chance to see the airplane side of our profession, in some small way. Although one of us got his Airframe & Powerplant repair certificate many years ago as part of his education at Embry-Riddle, he has never practiced as an A&P, and none of us have ever done anything like this before.

We have been at it since March, 2006. Given our lack of experience, we decided to attend a "builder-assist" program given at the Alexander Technical Center, in Griffin, Georgia, which is south of Atlanta. We had already decided that we would do a "Quick-Build" kit, in which much of the wings and fuselage are already finished. At the builder-assist course, we built up the empennage, that is, the horizontal and vertical stabilizers, elevators, rudder, and trim tab, from the "slow-build" empennage kit, that is, from pre-punched ribs and skins. It was a 3+ long busy days (they certainly don't build it for you!), but we left with a completed empennage, and a solid understanding of what we needed to do to finish our kit. All-in-all, a great experience, that we'd highly recommend. Since then, we have generally met two nights per week, after work, putting in about 4 hours each of real work. So far, we still look forward to it!

I expect that most of this blog will pretty closely track our builder's log, but I hope it will also be more than just a list of what we did. Even if we never get any useful comments, at least it will serve as a kind of diary for us to look back on, and remember what we did and why we did it. If it can inspire anyone out there in some way, that would be even better! Keep in mind though, that, like anything else you read on the web, don't go off and do something on your project just because we did it!! None of us is an aircraft engineer, so anything you take from this, use at your own risk!!!