Function takes_cone_formula 

pub fn takes_cone_formula(shape: NoseShape) -> bool

Whether a nose or shoulder of shape takes any of Niskanen’s closed-form cone (eq. B.3–B.6, times eq. B.8 for an ogive) in its transonic pressure drag (PressureDragCurve::new): a cone and an ogive wholly; a power series of exponent above ¾ and a parabolic series of parameter below ½ in part, as they blend toward the 3:1 cone. That closed form reads high against measurement from Mach 0.8 (issue #67), so a shape that takes it carries that issue’s warning.