 For example, the wing spar in a small aircraft may in fact be a simple I-beam with a solid cross-section, but in a larger design the upright part of the beam or "web" will be constructed as an open lattice of trusses in a triangulated structure.The effectiveness of a flight control such as an aileron depends mainly on its area and its distance from the centre of the aircraft - its lever arm.If the wingspan is doubled, the area increases fourfold and the lever arm doubles, making the aileron 8 times more effective.