Stan: I can send you photos of my Boelkow Jr 208C (certified A/C) . You
might be able to use the way the struts are attached. Also look up
MFI-9 ( very similar a/c).

Larry
Stan wrote:
Yes, I purposely boxed in the problem. Knowing the tendencies of this
group to easily venture outside the box (cliche intended) I didn't want


this thread going wild. Sheez, pretty soon someone would have said,
"that's not the way Zoooom would have done it...".


I was leaning towards a simple spacer but was looking for a little
lighter solution that doesn't put the bolts in so much bending.
Preferably a solution made from aluminum that can be riveted to the
spar.


The 701 is built crazy light. I'm amazed it actually can take the
loads though it only has a 1100# gross and is so slow that the gust
loads are minimal so that may be part of it. That and it's use of
.016 skins with huge skin panels that are purposely allowed to buckle.


Stan


wrote:
Dear Stan,

I don't mean to be picky but your question is based on a host of
assumptions -- the use of T-capped spar vs a C-channel, the aluminum
itself, and so on. Having created that particular box the odds are
overwhelming that existing solutions, such as two strut-attach straps
installed upon the shear-web with spacers & thru-bolts will prove to be
the most practical solution. Of course, then I have to define
'practical' :-) But given the venue in which you've broached the
question a fair definition would seem to be 'practical' in the sense of
a relatively inexperienced metalsmith fabricating a single copy of the
design in a home-shop type of environment.

Your chosen box also implies certain factors of cost and
serial-production that might be considerably different for a home-built
airplane.

For solutions outside your particular box you will probably have to
alter the box itself, such as considering a C-channel spar, or perhaps
one fabricated with stock L-type extrusions for the caps. The Zenith
CH-701 offers nice example of the latter in a design optimized for
one-off production in a home-shop environment. In that case, the
strut-attach fitting is little more than another, single, piece of
extrusion attached upon a doubler on the forward face (ie, the
unflanged side) of the shear web.

I'm sure that isn't the answer you were hoping to hear :-) Please
don't read it as a condemnation of your chosen design (ie, T-shaped
extrusions, etc).

-R.S.Hoover