Flyhighdave wrote:

Hi All!
I'm confused by the weight restrictions on most gliders.
As an example the Lak-12 specs show the following:

Empty weight: 794lbs.
Gross weight: 1433lbs.
Payload: 693lbs.
Max. Water 416lbs.
Max. Pilot: 242lbs.(110KG)

Why is the pilot weight restricted to a max. of 242lbs? It seems to me like the
difference between the empty & gross weights could be made up of any
combination of pilot, equipment & ballast as long as the gross weight is not
exceeded & the C.G. remains within limits. What am I not understanding here?

The difference is where the weight is carried:

- in the wings, it reduces the load on the wing spars, especially at the
root. That's why it's carried there.
- in the cockpit, it increases the load on the wig spares, especially at
the root. This is why there is a "non-lifting" parts (basically, the
fuselage) load limit, in addition to an overall limit.

The actual limit may also be set by things like seat and belt attachment
strength, not just the wing strength. You don't know, unless the
designer tells you.

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Eric Greenwell
Washington State
USA