Snecma is claiming a “complete success” on its first two test of its re-ignitable Vinci cryogenic upper stage engine under development for the European Space Agency’s Ariane 5 Midlife Evolution (ME) and all-new Ariane 6 launchers.
The test series of this fifth variant of the Vinci engine, named M5, will run for ten months and include 16 firing tests, to freeze the design by the end of 2014. Ariane 5ME, being readied to fly from 2017 or 2018, will boost payload by 20% to 12T compared to the current launcher.
The ME variant will also bridge the gap to Ariane 6, which will look to reduce costs, and increase flexibility, by replacing Ariane 5's cryogenic main stages with a modular, solid-fuel first and second stage configuration topped by a re-ignitable cryogenic fuel upper stage. That upper stage will be an adapted version of the Ariane 5 ME upper stage, equipped with the Snecma Vinci engine and specific propellant tanks.
Vinci is critical to the system. The HM7 engine it will replace has been in service since 1979, on the Ariane 1 through 4 rockets in increasingly powerful variants and, in its current HM7B version, on Ariane 5. The engine has been extremely successful and reliable, with more than 200 built. As Ariane prime contractor Astrium points out, HM7 combustion chamber technologies were adopted by NASA under licence and formed the basis of the reusable Space Shuttle main engines.
However, the engine is not re-ignitable, a shortcoming to be addressed by Vinci, which at 180kN will provide nearly three times the thrust of the HM7B. With a re-ignitable engine – and Vinci will be capable of five restarts – the upper stage can coast between firings, allowing for correction of speed and trajectory.
This capability will improve the precision of placing satellites in orbit, which saves the satellites’ own, precious fuel that is needed for station-keeping. Also, the velocity-correction capability of a re-iginitable engine will prove useful in missions to deep space.
Four Vinci development engines have been ground tested since 2005, logging over 15,500s of operation during 61 firing tests. The M5 variant of the liquid hydrogen-oxygen engine features the latest iteration hydrogen turbopump. Snecma space engines division director David Quancard says the latest variant “confirms the maturity of the technologies used, and the tests show the engine's excellent performance".
Ariane 6 is intended to lift payloads of between 3t and 6.5t to geostationary transfer orbit, suitable for orbiting the telecommunications satellites that make up many of Ariane 5's missions, along with government payloads.
Ariane 5 is highly reliable, but not very flexible; each rocket must be manufactured with a specific payload and orbit in mind. Thus the solid-fuel configuration of Ariane 6 is a critical part of the plan, to allow components to be built in advance and stored, to slash lead times.
To keep Ariane 6 costs as low as possible – and to ensure as much of its reliability as possible is retained - prime contractor Astrium has been charged with finding as many synergies as possible between Ariane 5ME and Ariane 6. Vinci is one of the most visible commonalities. The Ariane 6 first stage will be built of what are essentially stages borrowed from the all-solid Vega light launcher introduced to service in 2012.
ESA hopes to fly Ariane 6 from about 2021. Since the project was given the go-ahead at the November 2012 member states ministerial meeting, which settled on national contributions and priorities for a five-year ESA budget cycle, the agency has been pushing hard to get development moving in earnest. The next milestone in the project is expected in October 2013, with a preliminary requirements review.
Source: Flight International
