This project is devoted to the pre-development of Alphabus Central Tube (@CT), equipment, which belongs to the structure subsystem of the Alphabus spacecraft. This pre-development consists of designing, developing, manufacturing a Bread Board of the central tube in order to demonstrate feasibility and adequacy between Fiber Placement Process (EADS CASA in-house available process) and selected materials and designs
The first phase of the project, called the concurrent engineering phase, aims to choose as materials for the central tube the best carbon fibers with regards to mechanical performance (stiffness, buckling and stresses) and industrial considerations (procurement, costs, compatibility with Fiber Placement Technology). The other issue regarding this phase consists of analysing the best configuration for the shell of the tube between a monolithic and standard sandwich.
The next phase, once the fibers and configuration are frozen, consists of validating the feasibility and capability of sub-contractors to meet the technical requirements for @CT, through Bread-Board manufacturing (with the Fiber Placement process) and sample testing.
The @CT belongs to the @BUS primary structure which will provide a performance gap of more than +50% compared to the current SPCABUS 4000 or EUROSTAR 3000 primary structures.
The @BUS platform is expected to support up to 8.5 tons of spacecraft launch mass. With regards to the Central Tube, the use of the Fiber Placement Technology intends to be attractive both in terms of recurring costs and performances. Industrial interest would increase if the shell of the central tube could be wound in a single and automated operation (monolithic configuration) instead of a standard sandwich configuration which requires several phases and includes man-manufacturing.
The global shape of the tube is cylindrical. On its lower part, a ring called "Launcher Junction Frame" (LJF) provides the fitting between the cylinder and the launcher adapter. An intermediate ring called "intermediate frame", on the outside of the @CT provides a base for several I/Fs. On the upper side, the @CT is connected with the first floor through the First Floor Frame (FFF) .
The interface with launcher is the standard ACU 1666mm as described in ARIANE 5 User's Manual.
According to pre-development results, this baseline could be improved/modified accordingly.
The CASA central tube has been selected for Alphabus. The predevelopment has been completed with the manufacturing of a representative breadboard.