Control system tests begin for Vega’s main engine

The Vega development programme is performing a crucial series of tests during 2006, including engine firings, mechanical and electrical performance verifications, and system-level trials. Among the many test campaigns, measuring the performance of the control loop of Vega’s first stage was started in May.

Vega's first stage, known as P80, is a solid-fuel rocket motor which includes a Thrust Vector Control (TVC) system consisting of two electromechanical actuators that operate a movable nozzle. The TVC system moves the nozzle to control the pitch and yaw of the launcher (the attitude of the vehicle in relation to the flight direction) during flight.

In order to characterise the TVC behaviour under the various conditions that could occur during flight and to verify the functionality of the control loop, a dedicated validation facility has been constructed at ELV SpA, in Colleferro (Italy).

The TVC Validation Model allows examination of all aspects of system performance using fully representative hardware, specifically:

• the two electromechanical actuators, designed and manufactured by SABCA of Belgium
• their associated electronics unit – known as the Integrated Power Distribution Unit – also designed and manufactured by SABCA of Belgium
• a mechanically representative model of the rocket nozzle – designed and manufactured by Snecma Propulsion Solide of France
• a battery set employing lithium-ion technology – to provide a more complete representation of operational conditions in some test scenarios – designed and manufactured by Saft of France.

The design, manufacture and assembly of the components of the TVC Validation Model have been lead by Europropulsion SA, a jointly-owned subsidiary of Snecma Propulsion Solide (France) and Avio SpA (Italy), which is the Prime Contractor for the P80 main engine. The construction of the test plant, including mechanical parts and ground support equipment for electronic command and measurement acquisition, has been carried out under the responsibility of ELV SpA, the Prime Contractor for the Vega launch vehicle. The management of the P80 demonstrator programme is under the responsibility of the P80 Integrated Project Team (ASI , CNES and ESA), located at the CNES facility in Evry, France.

The TVC subsystem tests are expected to last for several months. They will allow checking of the control sequence that will be used during the first P80 motor static firing test, scheduled to be conducted in Kourou during the last quarter of 2006.

At a later stage, during the system test campaigns, the TVC Validation Model will also be used for overall system verification. It will be controlled by a test version of the Vega onboard computer and flight software, making use of the inertial measurement system simulator and the simulated flight dynamics environment.