A method of manufacturing a self-supporting, monolithic fuselage body, including engaging peripheral mandrel sections around at least one central mandrel section, placing uncured composite material on the mold surface, curing the composite material on the mold surface, and sliding the central mandrel section(s) out of engagement with the peripheral mandrel sections and disengaging the peripheral mandrel sections from the cured composite material without collapsing the mandrel sections. The peripheral mandrel sections each include a shape-retaining core of a thermally insulating material and an outer layer on an outer surface of the shape-retaining core. The outer layer has a coefficient of thermal expansion within the range of variation of that of the coefficient of thermal expansion of the composite material. A mandrel for layup and cure of a predetermined composite material in the manufacture of a monolithic fuselage is also discussed.