Nicholas Cafarelli wrote:
I should add that the testing I have done involved complete ribs. It
is my opinion that this most accurately predicts the true utility of
alternatives.

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To All:

Nick makes a good point here. I'm guilty of assuming everyone understood the
progression of the experimental process. Indeed, I had included a simple
rib-testing arrangement in the archive with the Practice Wing files.

I consider the individual gusset tests to be just the first step. Trying to
open up the box a bit, I have been using whatever gusset material and adhesive
came to hand to fabricate sample T-joints. When the sample appeared to justify
further study, a full rib was made & tested to destruction using the weight
distribution shown in the drawings. (Here again, keep in mind the drawing is
relative to the Practice Wing which uses a D-cell leading edge; the leading
edge is not included in the tests.)

Heavy paper of various types is showing the most promise as an alternative to
plywood. As a point of interest, all such gussets should be well sealed with
dilute varnish after the glue has cured. This not only protects the paper, it
serves to strengthen it.

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Another assumption I've made is that anyone wishing to check or duplicate these
experiments should only do so AFTER making and breaking a number of ribs
fabricated in the traditional manner. I've used 1/8" luan plywood (ie,
'doorskins') gussets as the 'lo-buck' example and 1/16" aviation plywood
gussets as the 'regular' example.

Using 1/4" sticks, ribs fabricated in the traditional manner usually exceed the
worse-case strength requirements by 2X or more.

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Based on the mail I've received, most American, Canadian and Australian
homebuilders are relatively wealthy (compared to me) and see little merit in
such experiments, whereas homebuilders in India, China and Africa tend to be
more willing to at least consider alternative materials (mainly bamboo and
paper) and methods, even to making your own plywood (ie, laminated shavings,
suitable for rib gussets) and other labor-intensive techniques.

-R.S.Hoover