The invention discloses a civil aircraft
fuselage bottom structure considering
impact strength, comprising bulkheads, outer panel
skin, long purlins and foam; on the foundation of arc-shaped
fuselage bulkheads, the contour of the
fuselage remains unchanged, upper architraves and lower architraves of the bulkheads are hoisted upwards, the arc shape of the bulkhead bottom is changed to the flatbottom shape, the lower part of each bulkhead is symmetrically provided with a piece of foam, the ends at the two sides of the foam are provided with non-closed-angle-shaped structures in certain height, the lower part of the foam is supported by ventral outer panel
skin, the top and sides of the foam adopt the outer panel
skin for supporting, the two sides and the top of the foam are provided with long
purlin structures which have the function of longitudinal reinforcement. The fuselage bottom foam structure of the invention can greatly improve the
crash resistance of the fuselage structure, the new structure consisting of the outer panel skin and the foam contributes to bearing distributed load, as a result, the fuselage bottom structure of the invention not only has good
crash resistance against ground
crash but also has good crash resistance against water surface
impact accidents.