Solid Rocket Motors Technologies For Ariane 6

ESA (European Space Agency) and CNES (French Space Agency) are managing, with the support of industry, numerous studies to identify a new launcher approach that could reduce the cost of the current Ariane 5 and Soyuz systems. Several possibilities are currently investigated for the so-called NLS or Ariane 6 concept that should cover from the Soyuz up to the ½ Ariane 5 payload capabilities, meaning from 3 tons to 6.5 tons on the GTO orbit. Among several possible solutions, two of them have been more particularly investigated by CNES with the support of Herakles (a Safran Group company issued from the merging from former SME and SPS) and Astrium Space Transportation. Both launcher architectures are based on large solid rocket motors (SRMs) for the first stage and the second stage and are using a cryogenic upper stage based on the Vinci engine. The first configuration is based on two new large monolithic SRMs, a P180 (meaning 180 tons of solid propellant) first stage and a P110 second stage. The basic configuration of the launcher is capable of 3 t GTO. The P180 thrust law is chosen in order to allow performance increase thanks to strap-on booster addition. A 6 t GTO capability is possible by adding 4 strap-on of around 40 tons of propellant. The second configuration is based on a single SRM in the range of 135 tons of propellant. Using three of these P135 motor for the first stage and the same P135 for the second stage allow to reach the 6.5 t GTO class. With only two of them on the first stage the 3 t GTO is easily covered. All these motors have been designed to be ‘compatible’ with the existing production facilities in French Guyana and could be quickly developed without large investments for grain casting and motor assembly. For each projects, this paper presents the main characteristics of the motor, their propulsive performances and mainly their technical challenges in line with the overall development logic and expected maiden flight of the launcher at the turn of the decade.