What aspect of an aircraft's design does not contribute to its lift generation?

The design aspect that does not contribute significantly to an aircraft's lift generation is the fuselage length. While the fuselage is critical for structural integrity, housing passengers and cargo, and providing aerodynamic form, its length does not directly influence the lifting capabilities of an aircraft. Lift is primarily generated by the wings and enhanced by other factors such as wing shape, lift devices (like flaps and slats), and the angle of attack.

In contrast, wing shape is crucial as it determines how air flows over and under the wing, impacting the effective lift produced. Lift devices modify the wing's characteristics to increase lift during critical phases of flight. The angle of attack is fundamental; by changing this angle, pilots can adjust the amount of lift produced until the critical angle is reached, where further increases may lead to stall. Therefore, fuselage length is not a factor in lift generation, unlike the other elements.