Wing Bending Relief
In fixed-wing aircraft, fuel is usually carried in the wings. Weight in the wings does not contribute as significantly to the bending moment in the wing as does weight in the fuselage. This is because the lift on the wings and the weight of the fuselage bend the wing tips upwards and the wing roots downwards; but the weight of the wing, including the weight of fuel in the wing, bend the wing tips downwards, providing relief to the bending effect on the wing.
When an airplane is being loaded, the capacity for extra weight in the wing is greater than the capacity for extra weight in the fuselage. Designers of airplanes can optimise the maximum takeoff weight and prevent overloading in the fuselage by specifying a MZFW. This is usually done for large airplanes.
Most small airplanes do not have a MZFW specified among their limitations. For these airplanes, the loading case that must be considered when determining the maximum takeoff weight is the airplane with zero fuel and all disposable load in the fuselage. With zero fuel in the wing the only wing bending relief is due to the weight of the wing.
Read more about this topic: Zero-fuel Weight
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As the torn bandrols of Napoleon’s war.
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He’ll make you deserts and he’ll bring you blood.
How could you fear a dearth? have not mankind,
Tho slain by millions, millions left behind?
Has not conscription still the power to weild
Her annual faulchion o’er the human field?
A faithful harvester!”
—Joel Barlow (1754–1812)
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to puzzle a bending gravestone for his sake,
to question this diminishing and feed a minimum
of children their careful slice of suburban cake.”
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—In New York City, U.S. public relief program (1935-1943)