Saturday, November 18, 2006

Tracking the Elusive Tracing Paper

Got a call the other night from a total stranger who identified himself as a fellow resident of northern San Diego county and a homebuilder too, who lives up near the Pala Indian reservation which puts him even farther out in the sticks than me.

He's trying to track down some tracing paper. He's apologizing fifteen to the dozen but he's not a draughtsman and he's bought these plans for a thang called an RW-20 and he'd like to try making some ribs but the rib drawing spans several pages and he's never done this sort of thing before and he feels really silly about calling me because a minor detail like tracing the rib drawing has blown him right out of the water before he's even gotten started. Help?

I was smiling. (Okay, I was laughing my ass off.) But I know what he was going through. The mere idea of building an "AIRPLANE" in capital letters with quotes around it. And the fact all the experts say to trace the drawing so as not to destroy the original, as if ten years from now some inspector was going to insist on seeing the original drawing and would chop off your head if you couldn't produce it.

"Grocery store," I told him. "Baking section. Look for ‘parchment paper.' Use a new Sharpie ink pencil."

High Stammer burbled out of the telephone.

"Regular pencil won't work because the paper is treated with some sort of anti-stick stuff but a Sharpie works fine. Or you can use waxed paper. Waxed paper makes great tracing paper but nowadays most folks don't carry those narrow-lead wax pencils you need to write on the stuff. Ink pencils work fine on waxed paper but you have to clean the tip now and then."

The phone is gurgling... never thought... never realized.... never dreamed of using...

"Or you could just drop by the shop and borrow my rib jig. It's for the RW-19 but the dash-twenty uses the same airfoil. That is, if you're using five-sixteenths stock. If you're making the ultralight wing with the quarter-inch stock, it won't work.. I think I've still got the router templates for the nose rib around here somewhere too. Hello?"

The phone had gone ominously silent. Then a lady came on the line. "Who is this?" she demanded. "And what have you done to my husband?"

- - - - - - - - - - - - - - - - -

Truth is, I haven't used real tracing paper since the late 1950's when it was replaced by frosted acetate and later by frosted Mylar. And I haven't done any T-square drafting since I stumbled upon a copy of DeltaCAD on the remand table at the CompUSA store in Escondido. Nine bux. Cheep.

DeltaCAD is a soopersimple 2D drafting program just a tad above a T-square & triangle and at least as easy to use. Now I do all of my lay-out work inside the computer. That means I get to make all of my mistakes on the display screen instead of on metal. Ditto for rib drawings - - or any other part of the airframe. I have to get it into the computer to begin with but that's an arm-chair sorta chore, something you do in increments whenever you have a little spare time.

But lotsa folks still copy the drawing of a rib onto tracing paper using a good old fashioned #2 yaller pencil. This message is mostly for them.

If you've got a bright enough light you'll find that plain white shelf-lining paper works perfectly well to make a tracing. Sliding glass door makes a pretty good light-table. Bounce sunlight against the back of your drawing, you can even use brown wrapping paper.

-Bob Hoover

PS - I wasn't foolin' about the rib jig. Roger Mann, the designer of the RW-19/20 (the -20 is a two-place with SBS seating; the -19 has a narrower fuselage with tandem seating) uses a very interesting wing with a fixed slat and Junker-type ailerons as well as an ingenious long-travel oleo-pneumatic landing gear strut made out of the front forks of an off-road motorcycle. Innovations of this sort are of interest to me so I bought a set of his plans and studied them, going so far as to make a short practice wing using his airfoil, strapped it to the top of my 1965 VW bus and ran it up & down Highway 395 to see how it worked. Which was good, except for that nice man from the California Highway Patrol... who eventually let me off with a warning.

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