Launch Vehicle Propulsion

The Aestus rocket engine powers the Ariane 5 bipropellant upper stage for the insertion of payloads into LEO, SSO and GTO.

Astrium Space Transportation is responsible for the complete Ariane 5 upper stage, under contract to the French Space Agency CNES.

The Aestus rocket engine was developed at the Ottobrunn Space Propulsion Centre during the period 1988 - 1995. The first operational flight of Aestus was on 30 October 1997 on Ariane 5 flight 502.

The Ottobrunn team are currently working on a modification to Aestus so that it can be re-ignited up to five times during its 30 minute flight. This modification will enable Ariane 5 to inject several satellites into different orbital positions.

More detailed information about Aestus can be found here.

The Vulcain rocket engine powers the cryogenic core stage of Ariane 5.

The Ottobrunn facility is responsible for the development and manufacture of the Vulcain thrust chamber comprising:

Regeneratively cooled combustion chamber.
Coaxial propellant mixing injectors.
Dump cooled nozzle extension.
Gimbal joint.

The LOX and LH2 propellant valves are also manufactured and produced at the Ottobrunn Production Centre.

The thrust chamber design is based on the regenerative cooling concept that was developed at Ottobrunn and has since been continually refined. Before its combustion, LH2 is pumped into a distribution manifold and then flows through closely arranged small tubular cooling channels within the combustion chamber wall. The LH2 then enters an injector head where it is uniformly distributed to 516 coaxial injector elements.

The coaxial injector elements cause the LOX and LH2 propellants to be mixed together. LOX is injected at the centre of the injector, around which the LH2 is injected. These propellants are mainly atomised and mixed by shear forces generated by the velocity differences between LOX and LH2. Although the injector design is complex, it does assure consistent and reliable combustion efficiencies greater than 99 %, which are reached in the remaining process in the combustion chamber.

At the combustion chamber, the mixed propellants are burned and accelerated up to sonic conditions. The combustion temperatures in the chamber almost reach 3250 degrees Celcius at pressures greater than 100 bar.

Combustion temperature control is achieved by the flow of LH2 in the cooling channels within the combustion chamber wall. This thin copper alloy wall, just 1.5 mm thick separates the combustion temperatures from the - 239 to - 120 degree Celcius LH2 cooling flow.

The final acceleration of hot gases, up to supersonic velocities, is achieved by gas expansion in the nozzle extension, thereby increasing the thrust.

The Vulcain thrust chamber operation is available on movie. (German language mpg file).

The Vulcain, together with other engines on test at Lampoldshausen, can be seen on the test movie (mpg)

Vulcain 2 is the new gas generator cycle rocket engine for the Ariane 5 core stage.

Vulcain 2 thrust chamber element

As with Vulcain 1, the Ottobrunn facility is responsible for the development and manufacture of the Vulcain 2 thrust chamber comprising:

Regeneratively cooled combustion chamber.
Coaxial propellant mixing injectors.
Dump cooled nozzle extension.
Gimbal joint.

Development and production of the Vulcain 2 thrust chamber is available on movie (mpg file)

The LOX and LH2 propellant valves are also manufactured and produced at the Ottobrunn Production Centre.

By making design enhancements to the Vulcain 1 engine and introducing innovative production technologies, the thrust of Vulcain 2 will increase up to 135 tonnes - an increase of more than 30% compared to its predecessor.

Vulcain 2 will increase the payload capacity of Ariane 5 to 6.8 tonnes.

More detailed information about Vulcain 2 can be found in a PDF file.

The HM-7 rocket engine feature Ottobrunn's unique regenerative cooling technology whereby hydrogen propellant is efficiently used to cool the combustion chamber before being injected for combustion.

HM 7 Engine Ariane 1

In 1973, the Ottobrunn team started development of the HM-7 thrust chamber for Ariane's upper stage rocket engine. Six years later, the HM-7 engine was successfully qualified with the first launch of Ariane 1 in December 1979.

With the introduction of Ariane 2 and Ariane 3, it became necessary to increase the performance of the HM-7 engine.

This was achieved by raising the combustion chamber pressure from 30 to 35 bar and extending the nozzle, thereby raising the specific impulse. The burn time was also increased from 570 to 735 seconds. The upgraded engine was thus designated HM-7B and was qualified in 1983.

The HM-7 engine versions have reliably powered the third stages of Ariane's 1 through 4 from 1979 to 2003.

The HM-7B engine, will be integrated from the third stage of Ariane 4 into the new Ariane 5 cryogenic upper stage - A tribute to the performance and flight proven reliability of an engine first developed 30 years ago. The resulting upper stage will be designated ESC-A (Etage Superieur Cryotechnique A) and will increase the performance of Ariane 5 to 10 tonnes.

Use of HM-7B on Ariane 5 is a first step toward increasing the launcher's payload performance. A second step will be the introduction of the new Vinci expander cycle engine to the new cryogenic upper stage, increasing the payload performance to 12 tonnes.

The Ottobrunn facility is responsible for the development and manufacture of the HM-7B thrust chamber comprising:

Regeneratively cooled combustion chamber.
Coaxial propellant mixing injectors.
Dump cooled nozzle extension.
Gimbal joint.

The LOX and LH2 propellant valves are also manufactured and produced at the Ottobrunn Production Centre.

Important principles used in the HM-7 combustion chamber were adopted by NASA under licence and it is this technology that formed the basis of today's US space shuttle main engines - the first reusable rocket engine in the world.

Vinci is an advanced expander cycle cryogenic propellant rocket engine currently under development. It will be the first European re-ignitable cryogenic upper-stage engine. The Vinci rocket engine is planned to enter service in 2006 on the new Ariane 5 cryogenic upper stage, designated ESC-B (Etage Superieur Cryotechnique B).

Unlike traditional turbopump cryogenic engines, the Vinci expander cycle engine does not need a gas generator to drive the LOX and LH2 turbo-pumps.

On 20 May 2005, the Vinci engine performed its first flawless ignition and hot-fire test at Lampoldshausen's P4.1 test stand. The test marked a further milestone in the development of a more efficient cryogenic engine for the future evolution of Ariane 5.

Ariane 5's new cryogenic upper stage is planned to enter service in 2003. As a first step, the stage will be powered by the well proven and reliable HM-7B rocket engine. The stage configuration with the HM-7B version is designated ESC-A (Etage Superieur Cryotechnique A).

Vinci will increase the payload performance of Ariane 5 to 12 tonnes and it will be possible to re-ignite the engine a total of five times.

Vinci is the first European Expander Cycle Engine. The Ottobrunn Space Propulsion Centre is responsible for the development of the Vinci Thrust Chamber under contract to SNECMA.

The Ottobrunn facility is responsible for:

Regeneratively cooled combustion chamber.
Coaxial propellant mixing injectors.
Dump cooled nozzle extension.
Gimbal joint.

The LOX and LH2 propellant shut-off valves are also manufactured and produced at the Ottobrunn Production Centre.

On 20 May 2005, the Vinci engine performed its first flawless ignition and hot-fire test at Lampoldshausen's P4.1 test stand. The test marked a further milestone in the development of a more efficient cryogenic engine for the future evolution of Ariane 5.

More detailed information about Vinci can be found in a PDF file.

The RS 72 is a bipropellant turbopump rocket engine developed together with Boeing-Rocketdyne.

The RS 72 is based on the Aestus engine used on the Ariane 5 upper stage. Performance is enhanced with the addition of a Boeing-Rocketdyne XLR 32 turbopump.

This 300 N cryogenic propellant engine has a vacuum Isp of 415 seconds - the highest value ever achieved in Europe for an engine of such small size.

Further information on the 300 N cryogenic engine can be found here.