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AN Confessions of An Airplane Nut Part 8 – Who’s In Control Wood is such a fun material to work with! It has grain, it has character, it has beauty. On top of that, it has strength and is fairly easy to cut and form. The tools you need are available just about anywhere for relatively affordable prices. Stains, paints, varnishes and other finishing materials are also easily available so it’s no wonder there are so many good woodworkers out there. Metal, on the other hand, is a bit harder to deal with for the average shop jockey. Luckily, in the case of the Pietenpol Air Camper, most of the metal parts are of flat stock where you need only cut out the basic shapes, drill a few holes and you’re done. Right? Right! In the first place, I have discovered that I accidentally purchased a tape measure with a sadistic sense of humor. Now I know the basic rule, “measure three times, cut once” but how do you deal with a tool that changes the parameters every time you use it? I have lost count of the number of times during this project that I have measured three times, cut the part, and then had to ride strict herd on my mouth or I would get it washed out with soap if my mother happened to walk in. One of the posters on the Matronics Pietenpol forum recently stated that he had made every part three times with the last one finally going onto the airplane. He got my ratio just about right and that can be pretty disheartening sometimes. It was bad enough with the wood parts. It is just downright disgusting when working with metal because it takes so much longer to get the part ready to throw away. Ok, ok, so it is not all that bad and there is some good lesson larnin’ going on that will be valuable later. It did show me that I was right in purchasing some of the more complicated parts from a master craftsman though, instead of getting paranoid about every single part being personally made. (Maybe the next project.) Anyway, I purchased the control stick assembly (with pulleys), elevator bellcrank, wheel hubs with shock absorbers, miscellaneous wing fittings, etc. from a gentleman (Ken Perkins) in Olathe, KS who has a shop in his basement that would rival the NASA Space Flight Center. He provided those parts plus a lot of useful information for a very reasonable fee and an offer to help out more if I get myself in trouble. (I ought to ask him where he bought his tape measure.) Control sticks, rudder bar (for the pilot), and rudder pedals (for the passenger) installed – can you guess what came next? That’s right – “airplane noises.” You would think that a 57 year old man would feel silly sitting in a partially completed airplane (sitting on a work table) in the shop just “a-yankin’ and a-bankin’ and a-grinnin’ ear to ear”, but you would be wrong. Now, if I can just get this sucker up on wheels. With the help of my spaceship designing son I moved the fuselage outdoors onto the picnic table then temporarily installed the horizontal stabilizer, fin, and rudder. We then started playing with the elevator bellcrank location until we found the perfect spot where the cables to the elevators would have the least tendency to droop onto the leading edge of the stab with the elevators at full down. This is a common problem with many completed birds which then have to have some kind of leading edge protection in place to keep the cables from rubbing holes in the fabric stabilizer covering. Because the two fuselage attach points are not parallel due to the sides converging as they move towards the tail, wood wedges had to be fabricated so that the mounting flanges did not bind. (Three more parts for the trash bin.) What a thrill to connect the control sticks up to the bellcrank with framing cord so that the bellcrank moves with the sticks. Gnarly dude! (More airplane noises – with photos this time.) Four of the precision metal parts I acquired from Mr. Perkins are the lower landing gear attachment / lift strut attachment brackets. These brackets go on the outside of the fuselage and are backed up on the inside by simple “L” shaped brackets. These “L” brackets were to become my first experience at metal fabrication. Each is cut from 22 gauge 4130 steel plate. Never having cut sheet steel before, and not having access to a metal brake, I wasn’t sure exactly how to do this. I didn’t want to experiment with my new band saw as those blades are expensive and the literature did not mention metal at all. I do have an old jigsaw that is on it’s last legs anyway so I purchased a couple of different metal cutting blades for it and gave it a try. By the way, you want to use ear and eye protection for this part. Believe it or not, this worked like a charm. Cutting speed is understandably much slower than with wood but the process was acceptably quick and did not overheat the metal (which I was somewhat worried about.) Granted, three of those parts went into the junk pile but through no fault of the cutting process. I now have all four bracket combinations cut, drilled, corrosion treated, painted, and installed. Finishing metal is
also something that needs to be learned and it is a little different than
finishing wood. Metal has to be properly protected against oxidation (rust) and
the chemicals used to do that treatment can be somewhat hazardous to work with.
In a bare-bones shop situation like mine the simplest method appears to be a
good, old-fashioned rattle can filled with zinc chromate or zinc oxide. This
stuff is available from dealers such as Aircraft Spruce and Specialty or Wicks
Aircraft. The warning label on the side of the can kind of opens your eyes if
you read it. I did read it and immediately got on the phone to my son to see if
I dared to use it. He said to follow the instructions carefully and “can I have
your stereo?” I hung all my waiting parts outdoors from a tree, wore long pants
and a long-sleeved shirt, purchased a rated respirator unit (for vapor
protection not particulates), and donned some latex gloves. It worked fine.
Where in the world is all this rain coming from? I need to get out to the airport and get some muscle memory time in before I forget how to fly and have to start all over again. That’s one good thing about having a project like this though – if I can’t go fly I can still go build. I am headed for the shop but let me leave you with a quotation from that famous pilot – Albert Einstein: “The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science. He to whom this emotion is a stranger, who can no longer pause to wonder and stand rapt in awe, is as good as dead: his eyes are closed.” Tom Stinemetze The Airplane Nut ____ | ____
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