Max Gross Weight Question

True, in most sailplanes the critical factor is maximum bending moment
of the wing structure; the critical location is usually at side of
body or thereabouts. However, depending on the type of wing attach
used, the attachment of the wing to the fuselage might not be
particularly critical.

At issue is that in most modern sailplanes, the wing main spars of the
right and left wings connect to each other with no direct connection
to the fuselage. All bending loads are reacted by the spars
independently of the fuselage. The connections between the wings and
the fuselage, usually located near the leading edge of each wing and
also near where the flap or flaperon hinge axis meets the fuselage,
react only lift loads through shear, and drag and thrust loads through
compression.

The term that is usually used for the weight of everything but the
wings is "non-lifting weight" or "non-lifting load." This includes the
fuselage and pilot, the tailplane, and all equipment carried on board.
This is basically all of the stuff that contributes to wing bending
under flight loads.

Thanks, Bob K.



On Mar 1, 3:53*pm, Brian wrote:
Tony has it right, it usually has to do with the Bending loads carried through the wing attach fitting to the fuselage.

What you are really looking for is what the Maximum Design Fuselage Weight is for the glider. This is what controls the Maximum Pilot Weight. If the wings have an extra coat of paint and filler on them you can count this extra weight as Ballast weight. Unfortunately not all manufacturer actually publish the Maximum Fuselage Weight.

Brian