Positioning of the Wing Relative to the Fuselage

Positioning of the wing relative to the fuselage is an iterative process dictated by the location of the aircraft CG at a desired position, expressed in terms of percent­age of the wing MAC. The aircraft CG is kept close to the quarter-chord position of the wing MAC. Unfortunately, at this stage of design, the aircraft weight and CG are not accurately known.

A designer’s expertise is the way to estimate the wing position relative to the fuselage as a starting point. Experienced designers minimize the number of itera­tions that could occur with “wing-chasing,” explained in Section 4.11. The CG posi­tion varies with aircraft loading, fuel status, and military aircraft armament carried. Positioning of the wing should be such that the aircraft stability margin is not jeop­ardized by extremes of the operational CG position.

For newcomers to aircraft design, this offers an interesting exercise: Very quickly, a “feel” for locating the wing can be developed. A starting position for wing placement relative to the fuselage is approximately at the middle of the fuse­lage (somewhat farther behind for aft-mounted engines).