Op zondag 16 februari 2014 18:16:26 UTC+1 schreef firsys:

The kicker here is the torsional load on the pylon from a ground
loop or possibly a spin plus recovery. Even if a carbon fibre
tube could approach the torsional rigidity/strength of a standard
fore/aft pin attachment in the fuselage, the structure needed
to distribute the pylon loads into the wing may be compicated.
But I am willing to be proved wrong.
John F


I doubt that's nearly as much of a factor as many think.

Ground loop loads, at least from the regulatory point are not that high. 400N, so about 70 kgf (155 lbsf) ultimate load at the extremity of tip, balanced by an opposite load on the tail wheel. (CS22-5?? from memory). Same for spin recovery loads; those are nowhere near as high as rudder deflection @ Va, which is likely the limiting load case for the pylon.

As for the wing structure; mounting the pylon in yaw is pretty trivial. You're simply loading the skin in pure shear, which is about the easiest connection possible. The pylon load and mounting it to the fuselage skin are the biggie, but nothing a few layers of carbon won't solve. Less certain about flutter, but then most of the modes that involve yaw have much lower inertia (sideways boom bending/torsion), 2-3 orders of magnitude less inertia as a fully ballasted wing.

Kingfisher and plncraze came up with this thesis on http://www.homebuiltairplanes.com/fo...ylon-wing.html

MANDATORY reading for anybody that thinks this is interesting. Not 1:1 applicable to full-scale sailplanes, but a most interesting read wrt pylon wings:
http://drum.lib.umd.edu/bitstream/19...i-umd-5315.pdf

Also this article by Johan Bosman has some interesting remarks about moving the wing up (article on the end of the page):
http://www.glidinginternational.com/...g_Stories.html