Space travel is not possible without launchers. Every space activity is based on this simple fact. Launcher systems connect Earth to space. They transport people and materials into space and deliver research and commercial satellites to orbit. Launchers provide the only way to conduct scientific research and ensure commercial utilisation of space. But to survive in today's competitive environment, access to space must also be economically viable. "Europe's response to this challenge is the new Ariane 6 launcher with its innovative, cost-effective and reignitable, next-generation upper stage engine. The combustion chamber – the 'heart' of the engine – and other important components are made in Germany. This is the result of the competence and skills – unparalleled in Europe – that have been developed thanks to, among others, funding from the Space Administration at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR)," emphasised Gerd Gruppe, DLR Executive Board member responsible for the Space Administration. Production at ArianeGroup in Ottobrunn began on 28 June 2017 – an important milestone for Europe's gateway to space.
The heart of the upper stage engine comes from Ottobrunn
A great deal of energy is needed for a launcher and its payload to escape Earth’s gravitational field. Ariane accomplishes this feat initially by using its main stage and solid fuel boosters. The upper stage, with the Vinci engine, takes over once the work of the boosters and main stage has been completed. Energy-efficient and reignitable engines are crucial to ensure optimal propulsion in space. "We have succeeded in substantially increasing the efficiency of the Vinci engine, while at the same time creating the capacity to reignite the engine five times. This means that a variety of payloads can quickly and reliably be delivered to their required orbits," explains Denis Regenbrecht, responsible for the Ariane programme at the DLR Space Administration. The main production task has been delegated to the French ArianeGroup location in Vernon: "But the heart of the engine – the combustion chamber – is built in Ottobrunn, Bavaria. This is where combustion takes place, which creates a thrust of 180 kilonewtons," Regenbrecht adds. Vinci uses cryogenic hydrogen (LH2: – liquid hydrogen at minus 253 degrees Celsius) as its fuel, and cryogenic oxygen (LOX – liquid oxygen at minus 180 degrees Celsius) as its oxidiser, after the expander cycle. First the fuel flows around the combustion chamber, cooling it down and evaporating. The gases produced by this process are used to drive turbopumps, which force the oxidiser and fuel into the combustion chamber, where they are burned together with the additional oxidiser.
German industry contribution
The combustion chamber in this next-generation engine is not built by the ArianeGroup in Ottobrunn alone. Many small to medium-sized enterprises (SMEs) from Germany are also contributing to the project. For instance, a large number of turned and milled metal components, as well as hoses and seals, are made by medium-sized companies in Bavaria.
Innovative methods reduce production costs
Innovative technologies like additive layer manufacturing (ALM) and powder metallurgy are used to manufacture the Vinci upper stage engine. "These two methods have substantial advantages compared to cast or forged products, as components involving complex structures can be produced in large numbers, without the need for mechanical reworking. The elimination of expensive manufacturing stages and simplification of the engine structure have cut the costs significantly," explains Regenbrecht.
Revolution in the launcher market
Cost-efficiency measures like this are absolutely imperative, as the situation in the space transport sector has changed radically in recent years – on the supply side as well as the demand side. "European launcher systems face growing levels of competition in global markets, which will intensify the price pressure in future. Ariane 6 is a response to this situation, as its launch costs will be approximately half of what they were with its European predecessor, Ariane 5," emphasises Regenbrecht.
Engine tested in Lampoldshausen
With its 79 successful launches, Ariane 5 is amongst the most reliable launch vehicles ever built. The engines of its successor are tested carefully to ensure the continuation of safe transport of payloads into space. The next-generation Vinci engine is being tested at the DLR Institute of Space Propulsion in Lampoldshausen.Test campaigns are currently underway on the P4.1 altitude simulation test stand to complete development of the engine design and to obtain qualification for flight operations. DLR scientists use these tests to acquire insight into the engine's behaviour, which the manufacturer ArianeGroup can then use to make final improvements.
During the ESA Council Meeting at Ministerial Level in December 2014, the member states adopted a resolution to develop a new launcher system, Ariane 6. Its purpose is to advance the engineering of the Ariane launcher and to ensure its continued competitiveness in the global market. This requires restructuring within the European launcher sector. In future, responsibilities, costs and risks will be reassigned between the European Space Agency and the continent's space industry. Many components used in the Ariane 6 will draw on the experience and technologies of Ariane 5. Here, engineers will add new elements that have proven reliable to existing platforms. This will enable the complete development of the new launcher system within five years. The first flight of the approximately 60-metre-tall Ariane 6 is planned for 2020. Depending on its configuration, the launcher can be equipped with two (version A62) or four external boosters (version A64) and therefore transport either five or 11 tons of payload into space. ArianeGroup is ESA's main contractual partner for the development and construction of the launcher system. Germany is contributing approximately 23 percent of the development programme's overall costs. The DLR Space Administration is coordinating the German ESA budget on behalf of the Federal Republic of Germany.