Earlier, Bill wrote:

...Stan Hall presented his analysis
of the Nimbus-4DB accident in Minden,
NV, 1999...

One aspect of Hall's report with which I will take issue is what is
meant by a "45-degree bend" in the wing. The report shows a diagram
that depicts a 45-degree bend as the wing bend at which the pilot must
looks upwards 45 degrees from the lateral axis to see the wingtip.

I don't doubt that that might be what witnesses reported seeing. What I
do doubt is whether that is what the factory meant when they said that
under static test their wing deflected about 45 degrees (46.5, to be
exact) at 8g.

When I was doing deflection calculations for the wing spar in my HP-24
project, it seemed that the most useful measures of deflection were the
angular deflection at any point on the wing, and ultimately the total
accumulated angular deflection at the wingtip.

This figure compares 45-degree bends as defined by Stan Hall and by me:

http://www.hpaircraft.com/misc/nimbus_bend.GIF

I'm not privy to what definition of deflection the Schempp-Hirth
factory used in saying that their Nimbus wing would bend 46.5 degrees
at 8g. However, if their definition is similar to mine, and what
witnesses saw matched Stan's definition, it would mean that the
aircraft was seen at a loading substantially greater than 8g.

Also, I will submit that witnesses often over-report wing bending, and
that photos often seem to exaggerate it. What happens is that the
witness or camera viewpoint is rarely very close to the aircraft
longitudinal axis, and the oblique angle of the view tends to
"compress" the wings laterally, exaggerating the dihedral and wing
bend.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com