stephanevdv wrote:
My club has some problems with a Ka-8. It seems the gluing of the spar
and the torsion box has been done with better glue than that of the
ribs. It has been done with another glue type: dark brown for the
former (probably Aerodux), yellow/very light brown for the latter
(Kaurit?). The latter type of glue seems to fail easily nowadays.
There was / is a general AD out for the Ka range of gliders to check all of the
joints (presumably where the lighter glue is) To my knowledge there have been
three failures of Ka wings due to glue joint failure. Two were on overpowered
winch launches, the third one the pilot lost much of his starboard wing behind
the airbrakes in flight, but landed safely. This appears to be a problem
specific to the glue used on these gliders, their storage conditions and their
structure.

Phenolic glues, like the more modern composites have a very long life. All
phenolic resins are black or brown, strong but not terribly flexible. The latest
epoxy resins are enormously strong, and seem to have indefinite life. They glue
buildings together with the stuff these days.

The main indicators of glue problems seem to be if the joints have been subject
to moisture over a long time.


However, metal structures are known to fail, too, and often without
warning, by metal fatigue. Normally, sailplanes are made over strong in
critical metal components, just to allow for this phenomenon, but it's
not foolproof.


Let me get this straight, you're complaining that the LP15's cockpit
is too big? That's a complaint I have not heard before about any
glider.


And yet, the Schempp-Hirth people are producing their "a" model
fuselage (Discus a, Ventus a) for that reason, some competition pilots
complaining that by making their cockpits too big (like the Standard
Cirrus), they were wasting possible aerodynamical advantages... These
fuselages are advertised for slim pilots not bigger than 1.75 m.

And I am eternally grateful to Klaus Holighaus for the armchair in my Std
Cirrus, even if it loses a little on L/D...


--
stephanevdv
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Bruce Greeff
Std Cirrus #57
I'm no-T at the address above.