The dynamics of aircraft rotation and lift-off and its implication for tail clearance requirements, especially with large aircraft

Abstract

Ground clearance requirements are considered in relation to take-off, treating lift-off as a dynamic manoeuvre. It is shown that ground clearance is defined by conditions about one to two seconds after lift-off. Simple calculations are presented which permit a rational assessment of the proper tail and wing tip clearance margins arising from the immediate post lift-off motion of an aircraft. These effects are potentially more severe for the larger aircraft and are aggravated on tailless designs by adverse elevator lift. Recommendations are made for the use of directors and autostabilisation in this context.