Compliant crown panel for an aircraft
An aircraft forward pressure bulkhead and an aircraft crown panel are described herein. The forward pressure bulkhead includes a malleable and deformable dome that is configured to “catch” foreign objects, such as birds. The dome is intentionally designed to deform in response to a foreign object strike that imparts at least a threshold amount of impact energy to the bulkhead. The dome is free of rigid stiffeners and non-deformable reinforcement members that would otherwise hinder the flexible characteristic of the dome. Practical embodiments of the bulkhead utilize fewer parts, are less heavy, and are less expensive than traditional bulkheads that utilize rigid stiffeners. The crown panel has similar compliant characteristics. The crown panel is designed to simultaneously deform and deflect in response to foreign object impacts such as birds and hail. The crown panel is formed from a monolithic one-piece material, such as aluminum, and various reinforcing features are integrally formed in the material.
1. An aircraft crown panel assembly for withstanding in-flight foreign object strikes against an aircraft, the assembly comprising:
an aircraft crown panel comprising a compliant area and an edge reinforcing feature;
a cockpit window frame including at least one window post and an aft window frame;
the edge reinforcing feature integrally formed in the aircraft crown panel and coupled with the aft window frame;
at least one transverse reinforcing feature integrally formed in the aircraft crown panel and aligned with the at least one window post; and
the crown panel is configured to absorb impact energy from in-flight foreign object strikes against the crown panel by flexing.
2. The aircraft crown panel assembly of claim 1 wherein the crown panel further comprises a generally convex outer surface of the aircraft and a generally concave inner surface of the aircraft, and wherein the inner surface is exposed to cabin pressure of the aircraft.
3. The aircraft crown panel assembly of claim 2 wherein the cockpit window frame comprises a right window post, a left window post, and a center window post, each of the right window post, the left window post, and the center window post integrally formed in the crown panel; and wherein the aircraft crown panel comprises a compliant area, a right transverse reinforcing feature, a left transverse reinforcing feature, and a center transverse reinforcing feature; wherein the right transverse reinforcing feature aligns with the right window post, the left transverse reinforcing feature aligns with the left window post, and the center transverse reinforcing feature aligns with the center window post.
4. The aircraft crown panel assembly of claim 3 wherein the cockpit window frame further comprises an aft window frame and a first window frame, and wherein the edge reinforcing feature of the aircraft crown panel comprises a forward edge and an aft edge, and wherein the forward edge of the aircraft crown panel is coupled with the first window frame and the aft edge of the aircraft crown panel is coupled with the aft window frame.
5. The aircraft crown panel assembly of claim 3 wherein the center transverse reinforcing feature has a tapered cross section.
6. The aircraft crown panel assembly of claim 2 wherein the crown panel is configured to absorb impact energy from in-flight foreign object strikes against the crown panel by flexing when the energy of the in-flight foreign object strike is less than a threshold energy and by deforming when the energy of the in-flight foreign object strike is greater than a threshold energy.
7. A method of fabricating an impact energy absorbing aircraft skin panel comprising:
forming the impact energy absorbing aircraft skin panel into a desired contoured shape from a monolithic material, the panel comprising a compliant area and an edge reinforcing feature, the panel further characterized by a substantially concave exterior surface and a substantially convex interior surface, the forming step further comprising reducing thickness from the monolithic material so as to form the compliant area and the edge reinforcing area;
forming a desired edge profile;
shaping a width of a span of the edge reinforcing feature; and
affixing the panel to an aircraft, the aircraft characterized by a cockpit window frame including an aft window frame and a transverse window frame connected to the aft window frame, and wherein the step of affixing the panel to the aircraft comprises fastening the edge reinforcing feature of the panel to the aft window frame and the transverse window frame.
8. The method of fabricating an impact energy absorbing aircraft skin panel of claim 7 further comprising:
bonding a layer to the aircraft skin panel.
9. The method of fabricating an impact energy absorbing aircraft skin panel of claim 8 further comprising:
bonding a partial layer to the layer so as to form a perimeter reinforcing feature.
10. The method of fabricating an impact energy absorbing aircraft skin panel of claim 7 , wherein the impact energy absorbing aircraft skin panel is monolithic.
11. The method of fabricating an impact energy absorbing aircraft skin panel of claim 7 wherein the panel further comprises a tapered profile that transitions between the compliant area and a perimeter.
12. The method of fabricating an impact energy absorbing aircraft skin panel of claim 11 wherein the impact energy absorbing aircraft skin panel transitions in a plurality of steps.
13. The method of claim 7 further comprising forming at least one transverse reinforcing feature of the panel disposed on the convex interior surface by removing material from the monolithic material.
14. The method of claim 7 wherein reducing thickness from the monolithic material comprises chemically etching the monolithic material.