Re: Alan Thayer's Graphlite Q1 Canard Spar


David J. Gall
 

Leon,

1) The rods are not bedded in flox. The rods are laid directly onto several
layers of +-45 UNI and then have several layers of +-45 UNI and one spanwise
UNI wing skins bonded directly onto them. The resulting trough in the skins
due to the spar trough not fitting the rods well is subsequently filled with
micro (not flox) to build out to the final airfoil shape. In my opinion,
this is not the best way to go since the micro might crack and/or pop out of
the trough, but at least it keeps the rods in direct structural bond contact
with the UNI rather than relying on a flox bed to carry the loads from the
rod pack (spar cap) to the skins and shear web.

2) I would have preferred to see the rectangular rods used because they
allow for a better bond of the individual rods to the uni skins through a
thinner layer of epoxy. That said, I don't think this spar is relying on
developing anywhere near the full strength of the rods since a rudimentary
calculation shows that the spar root upper cap, having 68 rods, is good for
an upward load of over 3200 lbs per wheel or roughly 11 G's for ground loads
alone (more for flight loads). (I think the spar is sized to limit
deflections since it is more than amply strong.) Thus, the bond of the
individual rods to the UNI is not heavily loaded and hence not that
important.

The rectangular rods might be easier to handle and require a smaller number
of individual rods, or their greater stiffness might make it difficult to
bend them around the anhedral joint. Overall, I'd say the current design is
just fine and there's no need to fool with it, except maybe to clean it up a
little in the spar trough detail.


David J. Gall

-----Original Message-----
From: Q-LIST@yahoogroups.com [mailto:Q-LIST@yahoogroups.com]
On Behalf Of Leon - C
Sent: Monday, November 21, 2005 11:01 AM
To: Q-LIST@yahoogroups.com
Subject: Re: [Q-LIST] Alan Thayer's Graphlite Q1 Canard Spar

----- Original Message -----
From: "David J. Gall" <David@Gall.com>
To: <Q-LIST@yahoogroups.com>
Sent: Monday, November 21, 2005 10:21 AM
Subject: [Q-LIST] Alan Thayer's Graphlite Q1 Canard Spar


Leon,

Let me propose a modification to Alan Thayer's spar trough
that would make
building the canard with the Graphlite spar a little
easier. Instead of
trying to cut the foam core in one pass from one set of
templates which
results in the spar trough not being the correct width from
root to tip, I
suggest doing a second cut for the spar trough only which
would allow for
the different taper ratio of the spar vice the taper ratio
of the canard
itself. Food for thought...?
David J. Gall
I hadn't yet noticed that his spar trough was of constant
width. Cutting
the cores minus the trough and then sanding the templates for
the tapered
trough for a second cut would make for a neater job. Bedding
the Graphlite
rods even with a tapered trough take quite a bit more flox
than you might
think, which adds weight. I had the thought at one time that
it might be a
better idea to switch to the rectangular cross section rods
but after a bit
of further thought have come to the conclusion that the bond
to the round
rods is probably superior due to the ratio of surface area/volume.

When I get around to his templates I'll add lines for the
tapered trough.
I'd really like to get back to work on my own Quickie, but between the
doctors and recalcitrant insurance companies it will be several months
before I have the money and both hands to get anything significant
accomplished.
==============
Leon McAtee
In need of a good Quickie building fix...........Mainlined if possible




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