The structure consisting of the wings, fuselage, and fin and tail plane (vertical and horizontal stabilizer) of an airplane. This structure has a clearly defined role: to resist all the extreme loads that can be experienced with no danger to the passengers, whether the aircraft be civil or military. The temptation therefore could be to overdesign the airframe and “play safe.” But an overweight civil aircraft would be commercially disastrous, and an overweight military aircraft could be outperformed. To put this matter into perspective, a civil airframe can be up to 40% of the total dry weight, whereas the payload may be as low as 20%. Thus a structure which is overdesigned by only 10% could reduce the payload by 20%. This represents the profit margin on many routes.