Ariane 5

European Space Agency * Arianespace * International Launch Service (ILS) * Astrium Space * EADS Space

As the central element of Ariane 5 is the main cryogenic stage (EPC). Its propellant load of 132.27 metric tons of liquid oxygen and 25.84 metric tons of liquid hydrogen feed the stage's Vulcain main engine. Vulcain provides up to 116 metric tons of thrust in vacuum.
The stage has an overall length of 30.5 meters from the Vulcain main engine's nozzle to the forward (upper) skirt. Its dry mass is 12.2 metric tons, and the liftoff mass with its load of cryogenic propellant is 170.3 metric tons.
Topping off the main cryogenic stage is the vehicle equipment bay (VEB)  of 1.56 meter lenght, which carries most of Ariane 5's basic electrical equipment, the guidance and telemetry systems, and the attitude control system.
The solid booster stage (EAP) uses two solid rocket motors, each standing more than 30 meters tall with 237.8 metric tons of propellant. The solid rocket motor is made up of three segments: the 11.1-meter-long aft (lower) segment, which is loaded with 106.7 metric tons of propellant; the center-segment, with a length of 10.17 meters and 107.4 metric tons of propellant; and the 3.5-meter-long forward (upper) segment, loaded with 23.4 metric tons of propellant. A propellant mix of 68% ammonium perchlorate (oxidizer), 18% aluminum (fuel), and 14% polybutadiene (binder) is used in the solid rocket motors.
The storable propellant upper stage (EPS) performs the final part of Ariane 5's mission, propelling the payload to the point of orbit injection.
This is the only stage on Ariane 5 that is not ignited for liftoff, and it is the only one that does not operate during the launcher's ascent through the atmosphere.
The upper stage's Aestus engine is fed by 9.7 metric tons of propellant (MMH fuel and N204 oxidizer). There is no turbopump in the upper stage, so the flow of fuel and oxidizer to the Aestus engine is created by helium pressurization of the propellant tanks. Aestus is a re-ignitable engine, and produces a thrust of 29 kN over a nominal run time of 1,100 sec. It delivers a vacuum specific thrustimpulse of 324 sec. The Aestus gimbals in two axes for pitch and yaw flight control. Gimbaling is controlled by electrical actuators that act on struts fixed to the Aestus engine's combustion chamber.
The fairing is  a two half-shell structure. The fairing has a 5.4 m outer diameter. It is  available in short, medium and long lengths. The long fairing is made of two parts, the upper one being similar to the short fairing. The SPELTRA is an external support structure permitting double launches. It is made up of a cylinder interfacing with the VEB and the fairing, and a cone section connecting it with the payload. The Speltra structure, which is positioned between the upper stage and the payload fairing, allows Ariane 5 to carry two primary payloads on a single flight. A "lower" satellite is accommodated inside the Speltra, while the "upper" payload is mounted atop Speltra and is protected by the payload fairing. Speltra has an inner diameter of 4.57 m. The standard Speltra version, which is 7.0 (cylindrical part 5.66) meters high, is sized for "lower" satellites of up to 4.6 meters tall in their launch configuration.  The short version of Speltra is 5.5 (cylindrical part 4.16) meters high and accommodates spacecraft of up to 3.1 meters high.
The Sylda 5 structure is housed inside Ariane 5's payload fairing, and allows the vehicle to carry two primary payloads on a single flight.
The mission's "lower" satellite is carried inside the Sylda 5 structure, while the "upper" payload is mounted atop it. Sylda 5 has a diameter of 4.6 meters, and exists in 7 versions to accommodate satellites in the lower position with a maximum height of 4.6 to 6.4 meters.
Sylda 5 is a cylindrical-conical structure manufactured from carbon-honeycomb sandwich panels, assembled by bonded joints, and bonded and riveted aluminum frames.
A spacer element, the ACY, is available in lenghts from 0.5 to 2.0 m in 0.5 m increments. It is a cylindrical ring spacer that can be used to vary the payload compartment height.

Ariane 5 programme improvments

The cryogenic main stage and solid boosters will undergo change as part of Ariane 5's Evolution program.  One difference will be the use of Vulcain Mk.2, an upgraded version of the Vulcain engine currently used on Ariane 5. Vulcain 2 will produce 138 metric tons of thrust.
Another change is the core stage's modification by a positioning shift for the common bulkhead between propellant tanks which increases the quantity of liquid oxygen that can be loaded. In parallel, the liquid oxygen/liquid hydrogen mixture ratio will be increased for the operating needs of Vulcain Mk.2.
For Ariane 5's solid boosters, the loading of an additional 2.4 metric tons of solid propellant in the upper cast segment will increase their maximum thrust from 685 metric tons to 714 metric tons each.
A new upper stage ESC-A for Ariane 5 will be powered by the same 6.5 metric ton HM-7B engine as used in Ariane 4's third stage. Designed for ignition once during flight, the HM-7B operates on liquid oxygen and liquid hydrogen. The stage for Ariane 5ECA will carry 14 metric tons of the cryogenic propellant. With the application of this upper stage, the launcher will have a payload capability of 7,300 kg in a dual-payload mission to geostationary transfer orbit (with Speltra) and 8,000 kg in a single-satellite launch.

Ariane 5 ES with EPS/Evolution

• EPC (main stage): Vulcain Mk.2 (+20% thrust), extra 15 tons propellant, lowered common bulkhead in tank; strengthened equipped forward skirt and equipped thrust frame

• EAP (boosters): welded sections (in production); extra 2.43 tons propellant in segment 1; strengthened skirts; lightened nozzle

• Storable propellant upper stage; extra 0.25 ton MMH fuel in tanks; 7 tons dual launch to GTO

Ariane 5 ESV with EPS/Versatile

• Restartable engine Aestus for upper stage; strengthened nozzle

• ATV missions, interplanetary flights

Ariane 5 ECA with ESC-A

• VEB: (Vehicle Equipment Bay) : lightened structure (composite structure)

• "A" cryogenic upper stage, based on use of Ariane 4 HM-7B engine (Ariane 4 H 10 third stage engine)

• 9.5 tons dual launch GTO

Ariane 5 ECB with ESC-B------->Ariane 5ME

• EPC (main stage): Vulcain Mk.3 (Vulcain 2+)

• EAP: extra propellant in segments 2 and 3

• "B" upper stage equipped with VINCI cryogenic engine : restartable engine and nozzle with extendible exit cone

• 11.5 tons dual launch GTO