Under-flap stiffener for aircraft
An assembly of longitudinal structural stiffeners for an aircraft including, in a front portion of the fuselage, a windscreen that is slightly recessed relative to the airplane nose, and a fuselage portion extending in alignment with the airplane nose up to the base of the windscreen. The stiffeners include a bending-resistance main plane and are arranged under the flap and connected to the fuselage along a force transfer line. For one or more of the stiffeners, the bending resistance main plane substantially coincides, at at least a certain number of points of the fuselage force transfer line, with the plane predetermined by the local normal to the fuselage surface and the longitudinal axis of the airplane. A method is also provided for calculating the shape of the stiffeners.
1. An assembly comprising:
a fuselage surface; and
a plurality of longitudinal structural stiffeners, the stiffeners comprising a main plane of bending resistance substantially perpendicular to the fuselage surface, being positioned below a portion of the fuselage surface and secured to the fuselage surface along a force transfer line;
wherein, for plural of the stiffeners, the main plane of bending resistance of the stiffener substantially coincides, in at least a certain number of points P i of its surface force transfer line, with the plane X Pi N i defined by the local normal N i to the surface and an already known impact axis X Pi ,
wherein the stiffeners have an “I”-type cross-section comprising a core and two struts at extremities of the core and perpendicular to the core, and
wherein the core forms the main plane of bending resistance.
2. An assembly according to claim 1 , wherein the surface is a portion of an aircraft fuselage of a flap, extending in alignment from an airplane nose to a base of a windshield, and at every point P i the impact axis X Pi is the same axis X of the aircraft's normal movement in flight.
3. A flap for aircraft, configured to be positioned between a nose and windshield of the aircraft, the flap comprising:
an assembly of stiffeners, the stiffeners comprising a main plane of bending resistance substantially perpendicular to a fuselage surface, being positioned below a portion of the fuselage surface and secured to the fuselage surface along a force transfer line;
wherein, for plural of the stiffeners, the main plane of bending resistance of the stiffener substantially coincides, in at least a certain number of points P i of its surface force transfer line, with the plane X Pi N i defined by the local normal N i to the surface and an already known impact axis X Pi ,
wherein the stiffeners have an “I”-type cross-section comprising a core and two struts at extremities of the core and perpendicular to the core, and
wherein the core forms the main plane of bending resistance.
4. A flap according to claim 3 , wherein at every point P i the impact axis X Pi is the same axis X of the aircraft's normal movement in flight.
5. An aircraft comprising:
a fuselage with an outer surface;
a plurality of longitudinal structural stiffeners comprising a core forming a main plane of bending resistance, substantially perpendicular to the fuselage surface, the stiffeners being positioned below a portion of the fuselage surface and secured to the fuselage surface along a force transfer line; and
wherein, for plural of the stiffeners, the tangent plane of the core of the stiffener substantially coincides, in at least a certain number of points P i of its fuselage force transfer line, with the plane XN i defined by the local normal N i to the fuselage surface and the longitudinal axis X of the aircraft,
wherein the stiffeners have an “I”-type cross-section comprising a core and two struts at extremities of the core and perpendicular to the core, and
wherein the core forms the main plane of bending resistance.