M. J. Hinderliter, J. Barnes, Lockheed Martin Aeronautics Company, Marietta, GA

Summary:

The current F/A-22 nose landing gear door is comprised of eight pounds per cubic foot glass/phenolic honeycomb core sandwiched between two carbon/epoxy skins. This design was re-evaluated at Lockheed Martin Aeronautics and will be changed as a part of the Advanced Aluminum Aerostructures Initiative with AFRL, Alcoa, and Remmele Engineering. Analysis of an aluminum bi-grid sandwich design was shown to have a slightly lower weight per square inch at the same bending and torsional stiffness as the current composite sandwich design. The aluminum sandwich design will be manufactured by mechanically snapping and adhesively bonding an outer mold line skin with the integral grid to an inner mold line skin. In addition to a slight weight reduction, the aluminum design reduces recurring part cost, simplifies external coatings schemes, and reduces part dimensional instability that was characteristic of the composite door.