Patent ID: 8292226

Claim:
A method for minimizing the weight of an internally pressurized aircraft fuselage of a type that includes an elongated tubular shell having a central axis x, opposite nose and tail ends, and a near-elliptical cross-section having a radius R(φ) at substantially every point along the x axis between the two ends, wherein: φ is a roll elevation angle of the shell varying from 0 degrees to +360 degrees about the x axis; R(φ) varies radially by no more than ±7% from a radius r(φ) of a true elliptical cross-section having a radius r(φ), a major axis of dimension 2·r max and a minor axis of 2·r min , a curvature Curv(φ) of the shell is defined as the inverse of the local radius of curvature of a surface of the shell and is associated with R(φ), and a curvature κ(φ) of the true ellipse is given by: κ ⁡ ( φ ) = [ r 2 + 2 · ( ∂ r ∂ φ ) 2 - r · ∂ 2 ⁢ r ∂ φ 2 ] [ r 2 + ( ∂ r ∂ φ ) 2 ] 1.5 , the method comprising: tailoring at least one structural attribute of the shell as a function of at least one of the elevation angle φ, R(φ) and Curv(φ) so as to reduce the weight of the fuselage relative to an identical fuselage shell in which the same at least one structural attribute has not been so tailored, wherein the tailored function is periodic for φ=0 to 360 degrees and has a period of 360/n degrees, n is an integer, and the tailored function includes at least two local extrema located within 15 degrees of the values of φ corresponding to a maximum R(φ) located near the major axis of the true elliptical cross-section.