Ariane 5 ES

Ariane 5-ES Launch Vehicle

The Ariane 5 is an expendable Launch Vehicle that is being operated by Arianespace. Astrium, an EADS company, is the prime contractor for the Vehicle and is responsible for assembly of the rockets. Astrium is the leader of various sub-contractors that contribute components of the vehicle. Ariane 5 is used to deliver Payloads to Geostationary Transfer Orbit and Low Earth Orbit. The Rocket launches from the Korou Spaceport, French Guiana. Ariane 5 rockets are manufactured under the authority of the European Space Agency and Centre National d'Études Spatiales (CNES).
Ariane 5 has logged 59 flights since the maiden flight in 1996. With that record it has become Europe’s workhorse and will be operated at least until 2015. The Rocket is a flight proven launcher with a record of 55 successes and 2 failures. Two flights were filed as partial failures. The Ariane 5 is the fifth rocket of the Ariane family, but has not been directly derived from previous variants. Over the course of the rockets operating lifetime, modifications were made so that different variants of the rocket are available. The Ariane 5 ES Version is equipped with all advancement improvements the ECA Vehicle has compared to previous Ariane 5 Rockets. However, the Evolution Storable Version has a Storable Propellant Stage that provides second stage re-ignition capabilities that is required to reach precise Orbits that can not be achieved with a single engine burn. The ES Launcher is only used to deliver ESA's Automated Transfer Vehicle to Orbit and has only flown twice before.

Photo: ESA/Arianespace

Ariane 5 ES Specifications


Type	Ariane 5 ES
Height	53m
Diameter	5.4m
Launch Mass	777,000kg
Stage 1	EPC
Boosters	2 SRBs
Stage 2	EPS
Mass to LEO	21,000kg
Launch Cost	$120M

First Stage


Type	Cryo Core EPC-E
Inert Mass	14,700kg
Diameter	5.4m
Length	23.8m
Propellant	Liquid Hydrogen
Oxidizer	Liquid Oxygen
Fuel&Oxidizer Mass	170t
LOX Mass/Volume	133t/120m³
LH2 Mass/Volume	26t/390m³
Guidance	From VEB
Propulsion	1 Vulcain
Thrust at Sea Level	960kN
Thrust (Vacuum)	1,340kN (250,000lbf)
Egnine Length	3.00m
Engine Diameter	1.76m
Engine Dry Weight	1,686kg
Burn Time	650 sec
Chamber Pressure	117.3Bar

Solid Rocket Boosters


# Boosters	2
Type	EAP
Manufacturer	EADS/LV, Europropulsion, SABCA
Length	31.6m
Diameter	3.05m
Mass	268,000kg
Propellant Mass	237,000kg
Fuel	Solid
Thrust	6,470kn (1,450,000lbf)
Burn Time	129 sec
Attitude Control	Steerable nozzle (7.3°)
Nozzle Length	3.8m
Nozzle Diameter	3.1m

Second Stage


Type	EPS
Diameter	3.94m
Length	3.35m
Inert Mass	1,275kg
Propellant	Monomethylhydrazine
Oxidizer	Nitrogen Tetroxide
Fuel&Oxidizer Mass	10,000kg
Guidance	From VEB
Propulsion	1 Aestus
Thrust	27.4kN (6,160lbf)
Engine Dry Weight	115kg
Ignition	Re-Ignition Capability
Burn Time	Variable, Up to 1,100sec
Thrust Levels	Only 100%
Attitude control	Roll, Pitch, Yaw Control
	Steerable nozzle (16°)

Vehicle Equipment Bay


Diameter	5.4m
Length	1.56m
Weight	1,300kg
Attitude Control	Independent
Propellant	Hydrazine
Propellant Mass	70kg
Design	Full Redundancy

Payload Fairing


Diameter	5.4m
Length	17.0m
Mass	2,500kg (5,512lb)
Separation	Pyrotechnic Activation (Actuators)
Construction	Sandwich Construction
	Graphite Epoxy Face Sheets
	Aluminum Core

Sylda


Diameter	4.56m
Length	4.90m (Variable)
Mass	425 to 535kg

Vehicle Description

Core Stage

The Cryogenic H173 Main Stage of the Ariane 5 Rocket is called the EPC (Étage Principal Cryotechnique) and is fueled by Liquid Hydrogen and Liquid Oxygen. When filled with propellants, the EPC weighs about 170 tonnes. The different tanks for LOX and LH2 are aluminum compartments that are very thin and have to be pressurized at all times to prevent them from buckling under their own weight. The LOX tank is 4.7mm and the LH2 compartment 1.3mm thick.
At the bottom of the EPC is the propulsion segment with its Vulcain Main Engine. Its development began in 1988 and it flew for the first time in 1996 on the first Ariane 5 mission which failed. Currently, the Vulcain 2 engine is in use for the Ariane Program as it is 20% more powerful than the original Vulcain. Vulcain is a gas-generator cycle rocket engine that provides 8% of Ariane’s thrust at liftoff – the rest being provided by the two Solid Rocket Boosters. The engine features regenerative cooling via a tube wall design and lower nozzle cooling capabilities. Turbopumps are used to feed the engine with propellants. The LOX Pump spins at 13,600rpm with a power of 3MW, the LH2 Turbopump rotates at 34,000rpm with 12MW of power. Engine ignition is accomplished with three pyrotechnic devices on the Ground Support Equipment side of the Launch Pad. The engine nozzle can be swivelled to control the launcher's trajectory. Pitch and Yaw actuators move the engine to the correct position which is determined by the Flight Control System.

Solid Rocket Boosters

Two Solid Rocket Boosters are mounted on the Ariane 5 rocket. Those provide 92% of thrust at Blastoff. They are referred to as EAPs from the French Title Etage d'Acceleration à Poudre. 237 tonnes of propellant are included in each Booster. Steel casings enclose the individual segments that are joined together. Those casings are 8mm in thickness and can withstand a pressure of 64bar. Unlike Space Shuttle SRBs, the EAPs are not designed to fly again. After being jettisoned 131 seconds into the mission, they fall back to Earth and are allowed to sink to the bottom of the ocean about 450km from the launch site. Occasionally, Boosters are equipped with parachutes for recovery and post-flight analyses. Booster separation occurs at an altitude of 60Km and is initiated by pyrotechnic devices and separation motors. After separation, the Boosters continue their uphill track for 100km before falling back to Earth. The solid fuel that powers the EAPs includes Ammonium Perchlorate, Aluminum Powder abd Polybutadiene. Thrust from the Boosters is transferred to the Rocket’s Body via to the so called JAVE element on the Main Stage to which the EAPs are attached.

Upper Stage

Unlike the ECA Version of the Ariane 5 Rocket, the ES variant uses a Storable Propellant Stage as its upper stage. It is called the EPS - Etage à Propergols Stockables. EPS uses storable propellants instead of cryogenics. These are loaded several days before launch into spherical tanks. A usual fueling load includes 3,200 Kilograms of Monomethylhydrazine Fuel and 6,600 Kilograms of Nitrogen Tetroxide Oxidizer. The Upper Stage is powered by a single Aestus engine that provides up to 27kN of Thrust. Aestus features a regenerative cooling system and a radiatively cooled nozzle extension provides additional thrust. The injector element's design utilizing coaxial injection causes mixing and atomisation of the propellants which provides improved combustion efficiency. The Engine can be re-ignited several times and burns up to 1,100 seconds during a nominal mission. Usually, two burns are needed to deliver ATV to its targeted Low Earth Orbit from where it makes maneuvers using its own engines. It is also used to perform a deorbit burn after ATV Separation to conduct a targeted re-entry for disposal of the rocket. The EPS stage for the ES Version of the Ariane 5 is using a reinforced design to support the large spacecraft.

Vehicle Equipment Bay

The VEB (Vehicle Equipment Bay) can also be called the ‘Brain’ of the launch vehicle. It houses the flight computers, electronics and avionics. Also included in the VEB are the inertial measurement units and an independent guidance system that is used to maneuver the stack after Booster Separation and especially during orbital coast phases after 2nd stage shutdown before the spacecraft are separated. It is located on top of the Main Cryogenic Stage and interfaces with the upper stage of the vehicle. The VEB is cylindrical in shape and can operate autonomously from launch to orbital insertion controlling all aspects of the vehicle including trajectory profiles and orientation. The intertial measurement units provide the information that the computers need to calculate the current position and required flight path to met mission criteria. One of the key features of the VEB is the attitude control system that is comprised of Hydrazine Thrusters that are used to orient the vehicle once the ascent phase of the mission is over. All systems of the VEB are fully redundant allowing components to fail without having an impact on mission success. Telementry relay and communication with the ground are also features of the VEB that are important to allow ground teams to follow the mission and take necessary actions should those be required.

Payload Fairing

The Payload Fairing is positioned on top of the stacked vehicle and its integrated ATV. It protects the spacecraft against aerodynamic, thermal and acoustic environments that the vehicle experiences during atmospheric flight. When the launcher has left the atmosphere, the fairing is jettisoned by pyrotechnically initiated systems. One system splits the fairing vertically, the other frees the to halves. The fairing then falls back to Earth and burns up in the atmosphere. Separating the fairing as early as possible increases ascent performance. Ariane 5 can be equipped with two different fairing designs. Both are cylindrical in shape, but their overall length and weight varies. Both types of fairing have an inner diameter of 4.57m. The shorter version is 12.7m in length while the large fairing is 17m long.

Payload Adapter

Payload Adapters interface with the vehicle and the payload and are the only attachment point of the payload on the Launcher. They house equipment that is needed for Spacecraft Separation and ensure that the ATV is secured during powered flight. Electrical and Communication connections are also part of the Adapter and route ATV Telemetry to the VEB for downlink. For ATV Missions, an improved Adapter is being used to accommodate the massive vehicle weighing up to 21,000 Kilograms.