Assembly and equipment

Igniter integration

The igniter which 'sparks things off' is simply a small booster, a device weighing more than 300 kg and measuring one metre tall (or long, depending on how you look at it).  It consists of three pyrotechnic charges which ignite in sequence until the gas emitted from the main charge ignites the S1 segment, which in turn ignites the other two segments. Integrating the igniter is another extremely complicated operation.  Apart from pyrotechnic aspects which are specific to this component, it must be integrated precisely in the centre of the S1 segment, a task which requires special equipment.

Assembly

Once preparation of the three segments has been completed, segment S3 is transferred to the integration cell using an air-cushioned 200-tonne transporter and is placed on the table pallet which will itself be positioned on the launch pad.  Segment S2 is connected to S3 using a mechanical interface known as an inter-segment link, then the same procedure is used to install S1 onto S2.  The mechanical interfaces connecting the segments are extremely complicated and require very careful handling.  They must undergo testing before integration to ensure that they are completely free of manufacturing defects.  When the three segments have been assembled on top of each other, the result is known as a solid propellant motor (MPS).  The next step is the production cycle for the dressed propellant motor (MPE).

Equipment

Until recently, the MPE production cycle was overseen by EADS-ST, partly in the Booster Casing Preparation Building (BPE) and partly in the Booster Integration Building (BIP).  Since the last quarter of 2005, however, responsibility for all stage integration activities has been transferred to Europropulsion.

Initially, this involves preparing the forward skirt (JAV), i.e. the upper part of the solid booster stage (EAP), as well as the aft skirt (JAR), the lower part of the EAP.  Essentially, this preparation, which takes place in the BPE, involves integrating electronic equipment in the skirts.  For the time being, this activity is still under EADS responsibility.  Once these skirts have been transferred to the BIP, they are fitted with separation rockets which will enable each stage to separate from the main body of the launcher at the end of combustion.  The nozzle swivelling system (GAT) is also integrated on the aft skirt.  As its name suggests, it will be used to manoeuvre the stage's nozzle.  It is worth noting that the JAR is prepared and integrated prior to assembling the segments, as it is impossible to position the S3 segment on its pallet without its aft skirt.  The forward skirt is fitted with a vibration absorber (DIAS), an elastomer-based system designed to allow localised flexibility between the main cryogenic stage (EPC) and the moveable bracket for the forward booster attachment and release mechanism (DAV).  For launches where the EAPs are expected to be recovered at sea for analysis purposes, the forward skirt is also fitted with a parachute recovery system.  Current responsibility for this activity also falls to EADS.  When the two skirts have been integrated with the MPS, the engineers must then integrate the electrical equipment (cable laying) and the pyrotechnic devices (installation of destructive charges) throughout the launcher.  The finishing phase comes last, concluding with logos being applied to the MPE.

Changing from a dressed pressurised motor (MPE) to a solid booster stage (EAP) involves various operational tests, which for the moment are the responsibility of EADS-ST.