Lessons

This page is just to have one place for me to keep track of all the little things I learned along the way.

Here goes…

Practice Kit:

  1. Everything is so tiny. I’ve been staring at picture on all the build sites, thinking things were bigger. The -3-3 rivets are TINY! The skins are a lot thinner than I thought they would be.
  2. Don’t take the blue off the skins if you don’t want to scratch the skins. I thought my workbench was clean, but after deburring one of the small sheets, there were small pieces of aluminum everywhere. I slid one of the sheets on the table and scratched the hell out of it.
  3. My cheap clamps are nice, but not perfect. I’ll need to get some higher quality ones. Also, I need to use the duct tape on the clamp face trick. They scratched the hell out of the sheet, too.
  4. I had to measure, mark, and drill the holes. No big deal, but I just noted that they really have you jump right in. I drilled into a spare piece of MDF I had laying around, but I didn’t drill far enough, so the clecos don’t have a fantastic grip. Oh well.
  5. I played around with pressure on the bit while drilling. I learned as a kid that when you have the spiral piece of metal coming off in one piece as you drill, that is the right pressure (which wasn’t that much more than the air drill itself).
  6. I learned that building is not going to be a piece of cake, but is going to be a lot of fun. That’s kind of a fluffy statement, but it’s true.
  7. The soldering iron leaves a mark during devinyling if you aren’t careful, be gentle, and go slow enough that it melts the vinyl.
  8. Deburring holes was very easy, even with just an oversize drill bit.
  9. Buy a nice countersink. I faked it with a drill bit, and the results will not be acceptable on the real project.
  10. Less scratches tonight, but still a lot. I need to get some scotchbrite pads and self-etching primer to rehearse the prep and priming phases.
  11. Go slow, take your time, read the plans, and be careful.
  12. The skins don’t look too bad, but I have a feeling there will be too many scratches to polish the final airplane. I’m planning on paint anyway, so I should be okay.
  13. Other things, I want to acquire some of the tank dimple dies for the understructure. Some of the skin to rib seams didn’t sit as nicely as I wanted, and I think the slightly deeper dimples in the ribs will accept the dimple in the skin better.
  14. Buy a bigger backriveting plate. I just have a 1 x1/2 x 36 inch steel stock. I had to be really careful to keep the rivets lined up. With a wider plate, I wouldn’t’ have had to move the skin around, which caused…
  15. …scratches in the skin. Next time I removed the vinyl from the skin, I am going to immediately replace it with painters tape. All of the scratches on the skin are where I removed the vinyl. This can be prevented.
  16. Priming. Using the self-etching primer is so easy, I think I may do all of the interior skin next time ( I only primed the rivet lines, where two pieces of metal would meet this time).
  17. I need a no-hole yoke for the rivets near the rear of the trailing edge. I managed with a thin bucking bar, but I didn’t like the results. A no-hole would make this a non-issue.

Tools:

  1. Double-check internet orders before clicking “submit.” I ordered 3/16″ clecos instead of 3/32″ clecos.
  2. Buy a big, QUIET compressor. Mine is big, but it’s loud. There are certain times of the day I am not allowed to use it (so I don’t wake up the puppies during their naps).
  3. Drill stops are a must. Don’t try to fake it with tubing, just order them.
  4. Every time you make a tool order, buy some clecos. You’ll end up with enough by the end, and you’ll have bought them along the way. I used clecos to get to the $100 mark at the Yard store and Avery, above which shipping is free.
  5. Buy a scotchbrite wheel before you start. I had to wait to finish the rear spar because I didn’t have one to break the edges nicely. They’re expensive ($65), but another must.
  6. 12″ drill bits (#30 and #40) are essential from the beginning of the project. I love them.
  7. Pop-rivet dimple dies suck. Buy (or borrow) a c-frame.
  8. PermaGrit sanding blocks rule. Buy the 12″ flat one. It makes the first step of edge finishing really easy.

Empennage:

Horizontal Stabilizer:

  1. Be patient while waiting for kit orders from Van’s. I got all hot and bothered about them not telling me about out-of-stock issues before I sent them my money, but ultimately, the timing worked out, and I’m now having the time of my life (halfway through the HS).
  2. HS-702 bending: I strayed from the plans a little. They have you use a 1/8″ bit to create a notch relief hole, then enlarge to 1/4″ using a unibit. I used snips and then a file. The second one turned out better than the first (which I hear is pretty common on everything in the project), and I had some trouble making them look perfect. (I know, things don’t have to be perfect, but it bugs me, anyway.) Biggest lesson learned: cut the flange in the correct place first, then unbend the flange to give you more material to work with. You can see in the top one in the picture below that I didn’t do this, and had to taper into the bend relief notch. (The bottom one below is better, nice straight line back to the relief notch.)
  3. More HS-702 bending: After trying a few methods in the vise, I ended up just lining up my bend line with the edge if the table, holding a wooden block over the piece, and putting a little pressure on it. If you go slowly, you can get 6 degrees pretty dead nuts on. I laid everything on top of eachother, and it all lined up very nicely.
  4. When prepping parts, do it with a soapy (or just wet) scotchbrite pad under the sink. The aluminum dust gets everywhere if you don’t.
  5. Don’t drill the HS-708 to HS-603 holes to #21 too early. I thought about adjusting my riveting pattern so I wouldn’t have to use blind rivets here, only to remember I had already drilled this to final blind rivet size. Bummer.
  6. HS-707 is a pain to cleco to the skin for the first time. Go slow, and don’t scratch the inside of the skin.
  7. HS-405 to the HS-601PP (skin): I didn’t do the top or bottom forward most hole, because I seem to be having edge distance troubles on the HS-405 and HS-702 spar. I checked everything and it seems to be right. I checked some other build sites to see if other people have run into this, no one mentioned it. Right as I was going to post a question on the VAF forums about this, a new thread popped up. Apparently this is a common problem, and the edge distance on HS-405 is not to be worried about. It’s a little confusing, though, given the prepunched nature of the parts.
  8. Here, I clamped HS-404 in place after having first marked holes and drilled #40 pilot holes in the aft flange. The instructions have you mark and drill pilot holes in the HS-405, but why drill from aft to forward, hoping you don’t run into edge distance problems when you could drill from forward to aft? For the outboard holes, I did use the HS-405 for pilot holes.
  9. Before disassembling the HS skeleton, make sure the inboard edges of the skin are flush with the HS-404 and HS-405 ribs. This isn’t required, just a nice thing to do.
  10. Devinyl parts inside, where it is warm. It comes off much easier than out in the garage where it is cold in January.
  11. C-fram dimpling: After thinking about the setup and trying a few things, I quickly realized I wanted the female dimple die underneath and the male dimple die on top. I set up the skin on 3 2×4s (I haven’t built a dimpling table yet because I wanted to see how I liked doing it) which was less than a 1/4″ above the female dimple die. Then I basically moved the c-frame around until the male dimple die was lined up (this way I don’t scratch the skin with a male dimple die while trying to locate the hole from underneath, like some builders do). Then I held the male dimple die down into the hole and…WHACK! Perfect dimple. I am far happier with these dimples than the pop-rivet dimple dies.
  12. After finishing each row, I put a line of blue painters tape on the outside of the skin. I learned on the practice kit to protect whatever I didn’t want to scratch. The tape will come off just before riveting.
  13. Scuff parts before dimpling. It’s easier to scuff without all of the dimples getting in the way.
  14. Make sure to follow the rule about manufactured head on the side with the thinner material. I hear it sometimes doesn’t  matter, but why go against the rule?
  15. Wrapped my bucking bar in tape. Not all of it, but most of it. You can still buck rivets through the tape.
  16. I needed a longer rivet on the  HS-601PP (skin) to HS-702 (front spar) to HS-405 (aft inboard rib) hole. The longer rivet Van’s calls out (AN426AD3-4, instead of -3.5) isn’t long enough. I needed an AN426AD3-4.5.
  17. Make sure to let parts completely dry from your clean and prep before shooting them with primer.
  18. I put a piece of blue painter’s tape (sticky side toward the male (exterior side of the skin) dimple die) between the dies and squeezed them together. I figured this layer of tape would help prevent some of the circles I am getting during dimpling.
  19. While bucking, I position the bucking bar (covered in tape) against any ribs or sidewalls underneath the rivet, push up on the rivet (to identify it from above), push it back down with the rivet gun, then move the bucking bar a few millimeters away from the aforementioned ribs or sidewalls. Sometimes you can use a finger to get a nice anchor, but you don’t want the bucking bar to be touching any metal, it will scratch things up at is bucks.
  20. Offset rivet sets suck. If you don’t have three hands (one on the rivet gun trigger, one on the rivet set to prevent it from rotating, and one to buck), the offset rivet set will spin and damage the part next to the universal rivet head. A straight set works much better. I
  21. Flush-riveting technique: I stick the appropriate sized rivet in the hole, cover with blue tape, then reach in with the bucking bar, and shoot with my flush set, which is also covered in blue tape. Then, I remove the rest of the clecos, put rivets in again, and move all this little pieces of blue tape over one. (Then I figured out that on the second round, I could remove all the blue pieces of tape and run a whole line of tape along the line. I just had to make sure verify which rivets I had the bucking bar behind by pushing up on it a little. you can then see the rivet pushing up behind the tape. Bucking bar in place, I can set the gun down on the rivet and shoot.) If you were counting, you noticed there are now two pieces of blue tape between the flush set and the rivet (and my fragile HS skin). This worked well for me, prevented further damage, and gave me some friction to help keep the set in place.
  22. Rivet gun air pressure: I am using about 50 psi for AD4- rivets and 40 psi for AD3- rivets. Make sure to hold your gun against your bucking bar and feather the trigger a little to make sure you are keeping pressure. Sometimes if I lower the pressure from 50 to 40 psi, then pull the trigger, all the pressure dissipates. Something to do with how my compressor’s regulator works. I just learned to double check before diving into riveting a part.
  23. I used 2 cans of 7220 self-etching primer for the horizontal stabilizer (and the practice kit). I primed all ribs and spars, and the rivet lines of the interior of the skin. Plan accordingly.
  24. I actually learned this from one of my high school jobs at Windline Sails (fiberglass sailboat repair), but there is no reason to keep using old sandpaper. I apply this rule to scotchbrite pads. It doesn’t take that many passes with pressure in the same spot to kind of wear out the scothbrite pad. I cut mine into 2×2″ pieces and use my thumb or fingers to apply pressure, but one piece really only lasts for about one rib (HS or VS). A new piece just works so much better, I think it is really better to use fresh scotchbrite pads as often as you can afford. (They are really cheap.)  Back to Windline. Dan basically told me I would be wasting the customer’s money if I didn’t use fresh sandpaper all the time, which I didn’t believe back then (I was 16; I wasn’t going to believe anything a superior told me), but I do now. Buy lots of scotchbrite pads. Also, I read somewhere that Gray = 120-150 grit, Maroon = 360-400 grit, Light gray = 800-1000 grit, and White = 1200-1500 grit. People say you can get away with only using Maroon on the RV-7, but I will probably buy some finer scotchbrite pads if I need to clean up some more aesthetic areas.

Vertical Stabilizer:

  1. Get some MEK early. I tried to use Goo-Gone to remove part stickers, and it takes forever. MEK. (With requisite gloves and respirator.)
  2. In areas where I have a lot of matchdriling to do, I use a dry-erase marker to mark the drilled holes. That alleviates the frustration of double-match-drilling a hole.
  3. Make sure you pull the blue vinyl off of parts when the parts are room temperature. It is much easier to remove than when they are cold.
  4. Consider starting with the vertical (before the horizontal). It’s easier than the horizontal stabilizer. Don’t actually do this, though, because you should always follow the directions. Notice I just said “consider.”
  5. See number 18 from the horizontal stabilizer section. Putting a piece of blue tape on the male dimple die significantly reduces the dreaded “dimple-circle” around the dies. I love this trick, and have not seen any negative repercussions.
  6. My hand squeezer doesn’t do well with AD-4 rivets. I don’t know if there is some deformation going on with the yoke during squeezing or what. I am tending to squeeze all AD-3 rivets and shoot and buck all AD-4 rivets. This won’t work forever. I might need to upgrade to a nicer hand squeezer.
  7. Buy the biggest steel plate you can for a backriveting plate. I started with a piece that was 1/4″ by 1.5″, and about 36″ long, but moved to a 3/16″ by 4″ one, about 48″ long. It works a lot better. (I got it from the local big box store for about $12. I know I overpaid, but I don’t know where the nearest scrap yard is yet.)

Rudder:

  1. I had been cutting the stiffeners following the center of the hole to the center of the hole method, but I found myself spending a ton of time filing down the edge to get rid of the half circles that left in the stiffener. I have since started getting smarter with the snips, making sure to cut on the correct side of the hole.
  2. Instead of using the dimensions on the plans to cut the rudder stiffeners, I just laid the spar in the correct place on the skin, and marked the stiffener in the appropriate place to give some clearance. See this picture to see the marks. You can see I had originally marked it long, but then came back and marked it more accurately after having traced the outline of the spar onto the skin.
  3. Don’t drop ANYTHING on your 0.016″ rudder skin. Ask me how I know.
  4. Make sure to cut the rudder horn brace on the conservative side of the hole. Many people have cut right to the middle of the hole, and did not meet edge distance requirements when matchdrilling to the skins.
  5. Don’t forget to include the rudder bottom fairing attach strips when riveting the skin to the bottom rib or else you’ll have to drill out 15 rivets. Ask me how I know.
  6. Pro-seal is not that bad. Change gloves often. Lot’s more here.
  7. When you rivet the reinforcement plates on the rudder spar, don’t forget to include the nutplates. Ask me how I know.
  8. My rivet gun pressure was set too low (I thought this meant I was being careful) while I was finishing up the rudder trailing edge. The gun wasn’t getting the job done before it jumped around a little and cause a couple very minute dings. A lot of my other dings have been pretty small, and these are even smaller. I doubt you would notice if I didn’t mention it, but I’m trying to capture my experiences here, so I offer it up as a lesson learned.
  9. Finally, when they tell you to flip the rudder over to finish the half-set backriveted shop heads, I’m not sure how this is supposed to work. With the long backriveting plate, the rudder is being supported by all of the proud shop heads, so if you rivet the manufactured head side, you’ll be adding a local bow to the trailing edge. I didn’t buy this, so I stuck with the first side and got the shop heads pretty well flush. Once that was done, I finally flipped it over to make sure they were backriveted flush.
  10. Buy a tungsten bucking bar. Don’t even think twice about it. It is worth the money. (And I am a cheap bastard!)
  11. While rolling leading edges, use tape along the whole length of the 3/4″ bar you are using to roll the edge. If you don’t, you can get some local bowing.
  12. Also, you want a smaller radius bend near the spar, and a larger radius bend near the blind rivet holes. If you just try to roll it in one go, you’ll get the opposite, and you won’t get a good fit. Look at this atrocious picture here.
  13. I got slick and used a facny setup for getting solid rivets in the last two holes of the top of the rudder. See here. It’s basically a backriveting plate, then the skin and upward facing rivet, a wedge (screwdriver!), then the downward facing rivet, then the upper skin, and a rivet gun. This was awesome, and worked great.

Elevators (I usually update these after the whole part is done, but I was updating it today and copied this one into the section. More later, of course.):

  1. Biggest lesson today was about the aft-most rivet in the stiffeners. When bending the skin out of the way to reach that rivet, everything twists out of alignment. If you start with that rivet, it is easier to make sure everything is flush than if you rivet the forward ones first. Start from the back and move forward. You will get better results.
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8 Responses to Lessons

  1. Dean Tener says:

    Hello Andrew,

    I’m building an RV9a, and I found your site as I was skulking around the web, looking for useful building tips. You’re a bit ahead of me, but not by a whole lot – I’m done w/ VS, HS, nearly finished with the rudder and about 1/3 of the way through the elevators. Currently getting a little tired of the scotchbrite, alodine, and primer routine.

    I have to compliment you on the “Lessons” list. Some really good suggestions there.

    Anyway, I wouldn’t be bothering you with this e-mail, except that I work for Honda, too. I work in vehicle dynamics simulation at R&D, in Raymond, Ohio. I have to assume that we’re the only two guys in all of Honda, who are building our own personal aircraft.

    Dean Tener
    dtener@oh.hra.com

  2. Steve Riffe says:

    Andrew, I have been following your log and wanted to let you know how much I appreciate the documentation. I am building an RV8-QB, and started almost exactly the same time as you did. I have completed the VS, HS, most of the rudder (need finish the roll) and am part way into the elevators. I realize that there is some difference between the 7 and 8 tails, but not a significate amount. I have (had) a goal of flying by mid 2013, but beginning to wonder about my time line. Originally, I had planned to be finished with the tail (except fiberglass) by June of this year. I compared my build times to yours and decided that either you’re fast or I’m slow. Here are my hours to date: HS 87, VS 31, Rud 37, Elev 18. Just thought I’d share some of this with a fellow builder. Keep up the excellent work and thanks again for the documentation.
    Steve

  3. Andrew says:

    Hey Steve.

    Sorry for not getting back to you sooner. I’m actually shooting for sometime in 2013 as well. (Getting the wings this August, planning fuselage next summer (2011), finish kit in 2012, then a mad dash to the end with engine, avionics, etc.)

    I think my build times are fast. I spend a lot of time outside of “building” just sitting around reading the manual, visualizing my next tasks, looking at build sites, etc., so when I go outside for the night, I pretty much know exactly where I need to start and what to do. I think that saves me a lot of “build-time” but not necessarily a lot of overall time. Who knows. Thanks for the nice comments.

  4. Stephan says:

    Hi Andrew,
    I saw your homepage and got several tips for my project. I am here in Germany and building my second 8.
    Question:
    Where do you have this pushrod Boots for $81 fromm? I couldn’t find any address at all.
    Thanks for answering
    Happy Landings
    Stephan Servatius
    Mauggen 89
    85461 Bockhorn
    Germany

  5. Andrew says:

    Hi, Stephan.

    I found the pushrod boots at Classic Aero Designs (looks like they are $77 now).

    http://www.classicaerodesigns.com/web/public/Products/ProductDetail.asp?ProductID=79&ProductCategory=RV-7&ProductCategoryID=12

    I’m not sure I’m going to go with these, as some people have plans online to make your own.

    Hope this helps.

  6. Adrien says:

    Hello Andrew,

    I was reviewing your build log and I really enjoy it.
    I’m currently building a MCR4S. It’s a small French carbon fiber airplane. (http://www.love4aviation.com/site/love4aviation/files/Aircraft/MCR_4S/mcr_4S_rotax_2Z.jpg)
    By looking on the design chapter, I saw that you are already studying various option for your instrument panel. I was doing it the old fashion way using a wood matrix :)
    Could you please tell what it the software you are using?

    Excellent job, your plane already looks great. congratulations.

    Adrien
    Annecy – France

  7. Andrew says:

    Hey there, Adrien.

    I’m pretty fortunate in that I have access to CATIA at work. During lunch breaks, I’ve been slowly teaching myself how to use it.

    The models aren’t complicated, and I’m sure could be duplicated on any 3D modeling software. (I’ve done similar stuff before using Google SketchUp. If you don’t have access to CATIA, I’d start there.

    Hope that helps,
    -Andrew

  8. Omar says:

    Hi Andrew,

    Following your logs with great details. I am building RV7A, working on left wing now. I however had to order many parts, twice or thrice. :-) That is before I found your website ofcourse. Keep logging please.

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