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Tuesday, June 24, 2008 - 8:30 AM

Alcan - SpaceX Al-Li Solutions for the Falcon Rockets

M. Niedzinski, Alcan Aerospace, Chicago, IL; C. Thompson, J. Richichi, J. Ayers, SpaceX, Hawthorne, CA; F. Eberl, Alcan Rhenalu, Issoire Cedex, France; S. Jambu, PECHINEY Aviatube, Montreuil-Juigné, France; R. Morganti, Spincraft Corporation, North Billerica, MA

Advances in materials and assembling technologies for launch vehicles and space structures are key aspects to reach increased payload for affordable and reliable access to space. Good weldability for friction stir and fusion welding are necessities for entirely welded tank walls and domes of  rockets. High static properties in the welded joint are needed in order to reduce wall thickness for increased weight reduction of the space vehicle structure. Good formability is essential for fabrication of complex domes.

The use of high strength and low density Al-Li alloys such as 2198 sheet and 2195 plate allows assembly of tank walls and domes by using friction stir welding in circumferential joints. These new generation alloys successfully replaced legacy alloys such as 2219 and 2014. Complementarily to the sheet material, the tank inner structure can be stiffened by using 2196 extruded stringers. The very low density 2196 material allows reaching at least 5% density reduction by reaching static properties of today’s flying 7xxx alloys.

After presentation of the main properties and features of the 2198 sheets, 2195 plate and 2196 extrusions, various examples of their application in SpaceX-Falcon rockets will be presented. Likewise some of the novel fabrication and joining technology will be discussed.


Summary: Recent advances in Al-Li alloys conbined with FSW joining technique resulted in introdution of low cost space launch vehicles such as Spacex's Falcon 9. Replacement of legacy alloys such as 2014 and 2219 with stiifer, stronger and lower density alloys such as 2198, 2195 and 2196 resulted lighter vehicles and significant payload increases.