Ariane 6 could use reusable Prometheus engine, designer says
LES MUREAUX, France and WASHINGTON — Europe’s upcoming Ariane 6 rocket, though designed to be expendable, could one day sport a reusable engine, according to Patrick Bonguet, head of the Ariane 6 program at ArianeGroup.
Whether or not the rocket would ever use that engine, called Prometheus, depends on whether Ariane 6 manufacturer ArianeGroup, formerly Airbus Safran Launchers, finds enough benefit for the European launch sector. So far, the merits of reusable rockets to ArianeGroup are unclear at best, Bonguet said, but the company is researching the technology to be ready for implementation should it prove worthwhile.
“We could replace Vulcain 2.1 by Prometheus,” Bonguet told SpaceNews. “Or Prometheus can be the first break to build the next generation. We will see where we are in 2025 or 2030, and then decide on the right time whether to go one way or the other.”
The Ariane 6’s maiden flight is scheduled for 2020, meaning the rocket would fly for at least five years or longer in an expendable configuration with Vulcain 2.1, a streamlined version of the Ariane 5’s Vulcain 2 liquid engine with the same performance.
ArianeGroup’s Prometheus engine received a substantial budget boost this year from the European Space Agency, which is paying the company via a fixed-price contract to build the Ariane 6 as a successor to the Ariane 5. ESA is supplying 85 million euros ($91 million) through its Future Launchers Preparatory Program, and began funding Prometheus in June.
Bonguet said ArianeGroup is studying reusability with Prometheus “in order to be sure to take the right path at the right moment.” Those efforts are mostly to prevent Europe from being caught flat-footed in the wake of other reusable launch systems, namely from SpaceX and now also Blue Origin.
Reusability is far from a primary focus, however.
“We still have not understood, would we save money by reusing? At least with our launch rate?” he asked. “We hope to launch 12 times a year. If we reuse 12 times, that means we only manufacture one time per year. It is difficult for us to have that.”
Bonguet said reusability would essentially erase the production efficiencies ArianeGroup is striving for, starving the Ariane 6 industrial base of the work upon which it relies.
A smaller tip-toe into reusability could come through salvaging Ariane 6’s payload fairings. Swiss manufacturer Ruag Space is developing reusable fairings, which Bonguet said are of interest to ArianeGroup.
“We are discussing with Ruag,” he said. “They have presented to us their concept. If it is working, and if it is bringing cost savings, we will be happy to accommodate it.”
Production value of Ariane 6
ArianeGroup is seeking a 40 percent price reduction for the Ariane 6 compared to the Ariane 5.
The biggest difference between the Ariane 5 and the Ariane 6 is the way the two rockets will be produced, Bonguet said. Compared to the Ariane 5, Europe’s Ariane 6 is factoring in production at the design stage. This includes leveraging an “extended enterprise” concept where ArianeGroup co-designs components with suppliers. Having production efficiency at the forefront of development will allow the rocket to be lower cost yet still reliable, he said.
“Ariane 6 is basically an industrialization of Ariane 5. So, it is not a brand new design. The innovations are more to make it robust to manufacture,” Bonguet said.
ArianeGroup also gains cost savings by leveraging the combined resources of French and German rocketry expertise, which was previously stratified as Airbus and Safran. Bonguet said it is a rational step to further integrate other parts of the Ariane 6 industrial base, but ESA member states would likely reject such integration to prevent losing domestic competencies.
A third means of cost reduction and improved production efficiency is with additive manufacturing, or 3D printing. Bonguet said the Ariane 6 will likely have around a dozen 3D printed parts, compared to just one on the Ariane 5. ArianeGroup is primarily using 3D printing to streamline the production of complicated equipment that is otherwise difficult to machine. The company is also using 3D printing to create an addition to the upper stage called the Auxiliary Power Unit (APU), which is fully 3D printed, he said. The APU is a low-thrust system that enables the Vinci upper stage to drop satellites in multiple orbits for constellation deployment, and can also assist in deorbiting the stage at the end of each mission.
Bonguet said the Ariane 6 is holding to its 2020 schedule, but ArianeGroup had to invest its own non-ESA resources into the test program to hold to that date. He didn’t label the size of the investment, but said ArianeGroup is building an additional upper stage in order to perform tests in parallel with the lower stage.
Bonguet said ArianeGroup will perform tests of the fully integrated Ariane 6 in the second half of 2019 into early 2020. In 2018, test firings will begin for the Avio-supplied strap on solid rocket boosters, he said.
ArianeGroup and Arianespace plan to overlap launches of Ariane 5 and Ariane 6 until around 2023. Bonguet said commercial demand for the Ariane 6 looks promising enough that the company is considering five launches in 2022.
Arianespace bought six more Vega and four Vega C from Avio last month, has yet to place an order for Ariane 6 rockets with ArianeGroup. To keep schedule, ArianeGroup is already buying long-lead items for the first batch.
“We have already ordered long-lead items covering up to launcher 15 already in order to be on time,” he said. “Industry is anticipating the start of production this way. We are doing this because there is an exploitation readiness key point organized by ESA and member states at the end of this year taking place in November-December, with a final outcome in March where the member states will formally endorse Arianespace with the operational role of Ariane 6.”
So far the first Ariane 6 customer is the European Commission for two Galileo launches. Bonguet said ArianeGroup is still waiting on a commitment from the European Commission to aggregate European government demand into a binding commitment for at least five Ariane 6 launches per year. This need, in order to ensure stable demand for the rocket, “is confirmed in principle,” but has yet to be confirmed in a contractual manner, he said.
The 1st nozzle of the P120 booster common to Ariane 6 and Vega-C on its way to Kourou
The 1st nozzle of the P120 solid rocket motor manufactured in the ArianeGroup plant in Le Haillan is en route for Kourou
The nozzle is an essential sub-assembly which creates thrust by ejecting themotor’s combustion gases
This new step confirms the progress made by the Ariane 6 program, which is on-schedule
The first images can be downloaded from XXXX
The first nozzle of the P120 solid rocket motor common to the future European launchers has just left for the Guiana Space Centre in Kourou (French Guiana). It will be fitted to the body of the booster intended for the first firing test on the solid rocket booster test stand (BEAP).
This nozzle, which makes use of the most advanced solid fuel technologies, was designed by the ArianeGroup teams on the Le Haillan site near Bordeaux.
For Yves Traissac, head of solid fuel propulsion at ArianeGroup: “The P120 nozzle is a model of technological success and design to cost. It meets the exacting demands of the Ariane 6 and Vega-C programs. This achievement is the result of the experience acquired by our teams with the Ariane 5 and Vega programs. This new nozzle comprises a number of highly competitive innovations, such as a flexible pivot with composite reinforcements and transfer of elastomers, jet path parts made of a new carbon/carbon material, a composite divergent nozzle with industrial winding and fullyautomated assembly.”
The P120 contains 142 metric tons of solid propellant, its lift-off thrust can reach 400 tons and the motor runs for 130 seconds. The nozzle allows very high speed ejection of the very hot gases (3,000°C) generated by the motor, thus creating thrust by transforming the energy of the combustion gases into kinetic energy. It can also pivot, which enables the launcher to be piloted. The technologies and materials used, including thermostructural(1) composites, are able to dealwith these extreme conditions throughout the motor’s operating period. The nozzle contributes to meeting the goals of the Ariane 6 and Vega-C programs: optimized costs, shorter cycles owing to a simplified design and the use of innovative technologies and processes.
Once assembled, the P120 motor will be tested on the BEAP in Kourou during the summer of 2018. Two other test stand firings will follow to qualify this motor before the flights of Vega-C in 2019 and Ariane 6 in 2020.
(1) Thermostructural: composite materials with excellent mechanical properties at very high temperature.
Design authority and industrial lead contractor for the development and operation of the Ariane 6 launcher on behalf of the European Space Agency (ESA), ArianeGroup coordinates an industrial network of more than 600 companies in 13 European countries, including more than 350 Small and Medium Enterprises (SMEs).