Hot fire tests of the Ariane 6 stages an overview

April 26, 2024

In the run-up to its qualification and inaugural flight, Ariane 6 underwent system tests from mid-2022 to the beginning of 2024. The aim of these test campaigns was to ensure that the complete sequence of launch countdown operations runs perfectly, that all ground and on-board systems and equipment work in complete harmony and that the launcher stages successfully withstand the trial by fire. We take a three-episode look back at these critical tests carried out in French Guiana and Germany – a true technical and industrial adventure.

The purpose of the Ariane 6 combined tests campaign at Europe’s Spaceport in Kourou was to check the working of the launch system as a whole, in other words the launcher functioning in synergy with the ground installations: launch pad, mobile gantry, control centers, propellant fueling systems, etc. These tests optimize launcher reliability for the first Ariane 6 flight. Each component, each control receives particular attention. Over and above the design and testing phases, forward planning and risk management are crucial for optimal preparation.

The combined tests in Kourou were carried out on a special launcher, the Combined Tests Model (CTM), which is fully representative of the launcher that will fly. The central core consists of real main and upper stages, capped by an upper composite with its payload adapter, its two half fairings and a dummy satellite. Four boosters are attached to the central core, one of which is a real booster with all its functional equipment. The only difference is that its solid fuel load is inert (for these tests, it was filled with sugar).

Practice makes perfect

Assembly of the combined tests launcher on the launch pad began in July 2022, with its upper part added in October of the same year. The teams then started the test campaign by gradually trialing and checking all the mechanical, electrical, and fluids interfaces between the launcher and its launch pad.

Numerous rehearsals were carried out for a step-by-step qualification of the various functions and operations involved in a launch countdown right up to the moment of lift-off. Complete countdown tests were then conducted in 2023, on July 18, September 5 and October 24, firstly with ignition of the combustion chamber of the main stage Vulcain°2.1 engine, then start-up of the engine followed by four seconds of stabilized operation. A long-duration test was held on November 23, then a test under degraded (non-nominal) conditions on December 15.

During these various tests, which lasted an average of 30 hours each, the teams were able to successfully trial various operating situations, including in degraded modes, for example the failure of certain equipment items. They covered all the tests needed for qualification of the Ariane 6 launcher, demonstrating that the launcher operations and its interface with the launch pad are consistently correct.

A team effort

The combined tests campaign ended on January 30, 2024, with testing of disconnection of the cryogenic connections between the launcher and the launch pad. These connections, supported by two retractable arms, supply the launcher with cryogenic propellant. They must be detached and moved away from the launcher extremely rapidly (a couple of seconds) in order to allow lift-off.

Throughout the campaign, the tests demonstrated that there is no technical or organizational flaw in the entire launch system. These results highlight the commitment, expertise, and rigor which characterize the personnel of ArianeGroup and its partners from the European Space Agency (ESA), the French space agency (CNES), and industry. They are also testimony to the strength of their underpinning approach which draws on technical expertise and teamwork, and are the fruit of a true collective adventure, one that very few people in the space industry get to experience during the course of their career.

The system tests enable us to check that all the subassemblies and equipment, which were developed and qualified independently, function correctly together to achieve the goal of a perfect countdown and launch sequence.”
Valérie de Korver, Ariane 6 system tests manager

The Ariane 6 program: who does what?

Ariane 6 is a program managed and financed by the European Space Agency (ESA), which is responsible for the overall launch system architecture.

As lead contractor and design authority for the launcher, ArianeGroup is responsible for the design, development, and production of Ariane 6, along with its European industrial partners, as well as for marketing launch services through its subsidiary Arianespace.

Upper stage tests are carried out in partnership between ArianeGroup and the German space agency DLR (Deutsches Zentrum für Luft-und Raumfahrt), on the DLR test site in Lampoldshausen (Germany).