This doesn't seem to jibe with something I recall reading somewhere.

Can someone set me straight on this before I go and build a bunch of junk ribs out of crappy wood?

Thanks

Nick

http://www.sirius-aviation.com/grade.html

In case anyone else is interested.

Anybody know of an aircraft grade sitka spruce supplier in Western Canada, preferably West Coast?

Thanks

Nick

Assuming the dealer has some Sitka Spruce, you can grade it yourself to A/C Grade----

No less than 10 growth rings(the lines across the end grain) per inch, measured perpindicular to the rings.

A slope of not more than 1 in 15 for the grain parallel to the
edge of the board.--(you can correct this yourself by sawing an
edge on a wide board parallel to the grain).

Ideally, the grain should be parallel to a face or an edge of the board.You probably won't find any with the rings parallel to the edge, as this is "edge grain" and is required for spars.Flat grain would generate more rib sticks, but you'll probably have to settle for something 30 to 45 deg angled, but this is OK, it just generates a little more waste.

You can correct this by angling the saw blade so that it is either parallel or perpindicular to the growth rings when you rip them into thin boards. At this time you should have a thin piece of plywood, masonite, or even aluminum, with a slit in it just big enough to allow the hollow ground fine tooth blade to penetrate.(this is to prevent the blade from dragging the thin strips down under the table & making you angry.
Your fence will have to fit over it, so it can.t be too thick .
Clamp it firmly to saw table. Ignore what knots you have, until the final sizing then cut the pieces you need from between the knots. If you're lucky you may get two sticks from each little board.
Your biggest difficulty will be getting some pieces long enough for the top & bottom strips.You may have to order some expensive stuff just for this purpose. when you are through, you will have a big pile of sawdust & angled scraps and a few good sticks.

Save the good angled pcs, they may make good glue blocks.

Some wiser heads will have to tell you which way to orient
the grain of the top & bottom strips.--( hope you don't get two
different answers.)

Jerry

When I was ordering rib materials I enjoyed a visit to the Wick's factory just outside of St. Louis. They began as a pipe organ building shop, and used a lot of Sitka spruce for the organ pipes they built. Gradually airplane builders found out about their supply of good wood and began asking to buy some from them. That, they told me, is how Wicks Aircraft Supply came into being.

They have a wonderful planing-dimensioning shop for their spruce. I ordered my rib materials from them and my rib stock arrived perfectly sawn and accurately dimensioned. That was several years ago, but I was extremely pleased. I recommend them highly.

For spars, I was fortunate to live near a real old-time wood and fabric guy, Gus Wiebe, at Halstead Airport in Halstead, Kansas. A visit to his shop is a real trip back in time. Gus and his sons take a trailer to your part of the world once every year or so and bring back beautiful spruce that they saw and plane into spectacular spar stock. Gus is getting up in years now, but could probably tell you where he buys his spruce if you called him. I am sure the number for the Halstead airport is available; also, his son, Dave Wiebe runs the El Dorado, Kansas, airport.

There is an old FAA publication that talks about wood grading...I don't recall the number but I am sure the EAA could help you find a copy. As an historical interest I also read some old engineering texts from the 20s-40s that talked about use of wood in aircraft construction. They have extensive descriptions of grain, etc as well as tables of mechanical properties for many different woods. The department of special collections at Wichita State University (Wichita, Kansas) is very helpful if you have an interest...they have many old texts because of the extensive history of aircraft manufacturing in Wichita (Travel Air, Cessna, Beech, etc). Most of the books I looked through were from the collection of Herb Rawdon, who was the chief engineer at Travel Air. If you would like to find out more, call the library at WSU, ask for Mary in special collections.

Enjoy!!

Paul Uhlig

This is beautiful old-growth timber, kiln dried, cut to spec, guaranteed free of defects. Here's the website:

http://www.timberwright.ca/index.html

for those who are interested.

Nick