area rule

noun

Definition of area rule

aeronautical engineering

: a principle used to design aircraft with minimal drag at speeds approaching and in excess of Mach 1

Note: The area rule states that the more closely the progression of the cross-sectional area of an aircraft's body from nose to tail matches the progression of the cross-sectional area of an aerodynamically smooth, idealized shape, the less drag will be generated.

Called the area rule, it says that drag at high speeds is a function of an airplane's total cross-sectional area (essentially, the thickness of the fuselage). Because projections from the fuselage increase a plane's cross section, narrowing the fuselage where the wings and tail assembly attach reduces drag. — Aaron Nicodemus, Telegram and Gazette (Worcester, Massachusetts), 16 Oct. 2009