Ariane 5 ECA - new elements
Ariane 5 ECA had a higher capacity Ariane 5 Generic launcher. Although it had the same general architecture, a number of changes were made to the basic structure of the Ariane 5 Generic version to increase thrust and enable it to carry heavier payloads into orbit.
Solid boosters
The upper segment of the Ariane 5 ECA boosters could carry 10% - approximately 2.5 tonnes - more propellant. This extra propellant gave the Ariane 5 ECA an additional 50 tonnes of thrust in the first 20 seconds following liftoff. This means that together the twin boosters delivered a thrust of 1400 tonnes at liftoff, nearly 10 times the level delivered by the engine of the central stage.
The boosters were also equipped with a new nozzle that had fewer parts and was easier and cheaper to produce.
Main stage
The Ariane 5 Vulcain cryogenic main-stage engine was modified to increase its thrust by 20% to 137 tonnes. This new version, called Vulcain 2, operated under slightly higher pressure with a mixture ratio that had 20% more liquid oxygen than the Vulcain 1. Because of this change in the mixture ratio, a new oxygen turbopump was developed capable of operating at 13 000 rpm to deliver a pressure of 161 bar. To hold the extra liquid oxygen needed for the central core stage operation, the capacity of the liquid oxygen tank was increased by 16 tonnes.
In addition, the Vulcain 2 engine had a new nozzle to allow exhaust from the turbopumps to be reinjected into the main system, thus improving the engine performance at high altitude.
Thanks to these modifications the Vulcain 2 engine was able to provide an additional lift capability of 1.3 tonnes into geostationary transfer orbit.
Cryogenic upper stage
Ariane 5 ECA had a more powerful cryogenic upper stage able to contain 14 tonnes of propellant. The cryogenic upper stage was powered by the HM-7B engine used by the extremely reliable Ariane 4 launcher.