Wednesday, November 21, 2007

Cooking Airplane Ribs

Do any amount of travel, you gotta eat. Good trip, say up to Alaska or down through Central America, you’ll be gone thirty, forty days. That’s a lot of cooking. Even when you do your traveling by airplane, boon-docking old mining sites in the Mojave or whatever, you gotta eat, although going airborne, you generally do the cooking at home, rig it so’s you can eat it cold or just an aluminum-wrapped something you can lay on the coals of a fire.

If you write about your travels the facts of feeding yourself tend to creep into the typewriter so that pretty soon, thanks to blogs and Newsgroups and stuff like that, folks become aware of Bob’s Basic Biscuits, Beans a la Boom, Bajanese Salad and the other recipes - even cookies - that have made life away from home a bit more enjoyable and deserved mention because of it.

The point here is that most folks who drop by the shop are used to me putting down my tools to go check something in the oven, especially during the holidays when I shift into Pie-Making Mode. Which is what I was doing when The Visitor arrived, and why I carried the timer out to the shop as we went.

“Pies,” I said.

He nodded in understanding. “My wife said you had a good cookie recipe.”

We chatted about cooking while I replaced the stripped nut-plate on his spinner backing-plate, which was why he’d dropped by. While I worked he glanced around the shop but there wasn’t much to see. Major projects are on hold due to a lack of funds. To fill the time I’ve been doing some experiments with cardboard ribs and other such stuff. Actually, they’re not cardboard at all, they’re plain old-fashioned stick-ribs. But the gussets are made from heavy paper, like the stuff used to package a 12-pak of soda pop. Or the better stuff used to package a 12-pak of Colorado Kool-Aid. (This isn’t new, by the way. For the past several years I’ve posted occasional messages about alternative materials, including several recent articles posted to my blog.)

The ‘cardboard’ appellation came from a gentleman who took me to task for daring to even mention such a ‘stupid’ idea, unaware that paper or ‘fiber’ gussets had already been used by a pair of bicycle boys named Wright, a company called Aeronca, the late Paul MacCready and a few others dummies. Unfortunately, their work with paper gussets hasn’t made it onto the internet forcing all future dummies - like me - to conduct our own experiments. And to write about it so that when I fall screaming from the sky the NTSB can simply hit a button, peruse a few million words of gibberish and say: ‘Ah ha! When he made his casein glue he failed to properly neutralize the mixture!’ ( er... actually, the casein glue is another set of experiments. And if you read a bit farther down that page and you’ll see that my home-made casein glue worked jus’ fine, thanks... although I wouldn’t want to use it except in an emergency... such as living in a village in rural India... or being even poorer than I am.)

Among the many details no doubt included in the missing body of literature describing the use of fiber gussets is the fact they are hygroscopic, something I had to rediscover for myself. Unless treated, paper absorbs water. Since the ‘fibre’ I’m using is various grades of paper obtained by a series of dumpster dives, it too absorbs water. (My neighbors already have good reason to believe I’m crazier than a hoot owl in heat. When they found me fighting off the ‘possums to get at their garbage it produced only a few sighs of resignation and a request to put the lid back on when I was done.)

Since paper is hygroscopic that means some of my experiments have dealt with ways of waterproofing the stuff after the rib is assembled. So far, dilute varnish seems to be the best solution but the tricky bit was discovering I had to use at least two coats, the first being no more than 50% varnish. Of even more interest, at least to me, was determining the ideal moisture content for fiber gussets, and how to adjust it when the paper is too wet or too dry.

Which is why I shoved the repaired backing-plate into his hands and went scurrying into the house when the timer dinged. The pair of punkin’ pies were baking slowly to perfection on the top shelf but the cookie sheet of gussets cut from a Coors carton were done to a turn. The pies had to be baked; that’s what Thanksgiving is for, right? And it was just plain old fashioned common sense to slide a sheet of damp gussets in with them.

I come back out to the shop with the cookie sheet on high, put it gently on the bench and inspected the result. My nose told me the paper hadn’t been over-heated. By positioning the triangles of cardboard on the cookie sheet with their printed-side down I’ve found I can estimate their dryness by the amount of their curl. Ten minutes seemed to be just about perfect for that particular batch. And I may have said something to that effect as an aside, so the visitor wouldn’t feel slighted that I’d interrupted him by dashing off in mid-sentence. But when I turned his eyes were as wide as port-holes.

“Gussets,” I explained. He nodded then looked at his watch like he’d just discovered it lurking there on his wrist.

“For the ribs,” I waved toward the cardboard heat-box inside of which - and thus invisible to the normal eye - there was more than dozen ribs basking in seventy-degree warmth from a twenty-five watt light bulb.

“Right,” he says, edging toward the door. “Clare will probably want the recipe.” And with another mumble - glance at his watch he’s like, gone!

That’s when I figured out that he’s probably never read the posts about Chugger’s Rib and has no idea in the blue-eyed world that I’ve been searching for the Holy Grail. Or low-cost ways to build airplanes.

-21 Nov 2007


I'm afraid the gussets made from Coors 'Long-necker' packaging material haven't worked out. Turns out, the printed side of the package is coated with a plastic film that prevents the dilute varnish from soaking into the paper.

Although the gussets are more than adequate when it comes to their dry strength, if you can't prevent them from absorbing moisture you'd be better off to stick with plywood.

I will continue the experiments using the packaging material for 'Sprite,' of which I'm accumulated a good supply. Its thickness is only 0.017" (The Coors stuff was 0.030") which is right on the ragged edge for dry compressive strength and it takes only a tad of moisture (a foggy night will do it) to cause the gusset to fold up under a load. But when given two dilute coats of varnish the 'Sprite' gussets have survived my 'soak-test' -- leaving sample, varnished, gusseted T-joints in a pan of water over night.

So it goes.


Although a broken rib can be repaired, these things started out as scrap lumber. The last couple of nights have dipped into the low 40's, cold for southern California, and we heat with wood. The failed experiments were used as kindling but to their credit, some of them put up a hell of a fight on their way into the firebox :-)

-24 Nov 2007


Wm. Curtis Chapin said...

Good morning Bob -

I hope the pies didn't pick up too much of the cardboard gusset flavor!

Thanks for the effort you put into the blog. I enjoy reading it and look forward to each post.

Happy Thanksgiving to you and your family.



Anonymous said...

Happy Thanksgiving, Bob!!
Thanks for all the effort you put into sharing your engineering experience and insights! Between this effort and your "Sermons" from early days, you can't begin to imagine the lived you touched. There's a thriving new generation of aircooled VW enthusiasts and I share your tips & tricks with the "young'uns" at every opportunity. Most of 'em see the wisdom therein and take it to heart, and the few that don't probably couldn't be reached with a 2x4, anyway. :)

So Thanks! And pass the eggnog.


aircraft parts said...


That was a nice story. Cooking at airplane lets you enjoy more.