1913. Aluminum Lithium for the F/A-18, Hornet 2000

Paper

Abstract

The F/A-18 Hornet 2000, a derivative aircraft for the US Navy, entails a 20% increase in aircraft weight empty due to avionics systems upgrades, survivability improvements, increased wing size, and fuselage lengthening. Weight saving methods evaluated included substituting aluminum lithium for aluminum without detail part redesign. A prerequisite was that the material properties be at least as good as those of the material being replaced. Due to time constraints, a parametric weight increment had to be used for the configuration evaluations. However, as the Hornet 2000 study progressed, it became apparent that a detailed weight analysis was needed to increase confidence in this weight increment. This analysis included three phases. First, a material study determined what alloys, forms, and material properties of aluminum lithium were available. These material properties were compared to those of the aluminum alloys on the F/A-18. The next phase of the study involved merging data from a weight database and a drawing database to obtain a detailed listing of parts which could potentially be changed to aluminum lithium. Once this list was created, individual part weights were added to find a total weight to be converted. Potential weight savings, assuming current day and projected 1990 technology, were then derived using a 9% density reduction. Results of the 1990 technology weight savings were than extrapolated to a projected weight savings for Hornet 2000. The third phase of the study was to create a pictorial summary of the potential parts which could be changed to aluminum lithium based on 1990 technology.