Planning for Europe's Next Generation Launcher
by Ed Kyle Updated 12/03/2014
Ariane 6-4 Booster Separation
On December 2, 2014, the European Space Agency Council at
Ministerial level agreed to accelerate Ariane 6 development while foregoing previously
planned Ariane 5 ME development. The Council selected a new Ariane 6 design that
represented months of engineering and political compromise. The new rocket, expected
to enter service in 2020, will replace Ariane 5 and, likely, Soyuz out of Kourou.
The new Ariane 6 design will use two liquid hydrogen stages
boosted by two to four monolithic solid rocket motors. It is based on a mid-2014
Airbus-Safran joint venture proposal that won out over the previously approved CNES
"Multi-P" design. Unlike earlier cryogenic core designs, the first stage
will be powered only by a single Vulcain 2 engine that will produce about 138 tonnes of
thrust. It will be loaded with up to 149 tonnes of propellant. The second
stage will be loaded with about 30 tonnes of propellant and will be boosted by the Vinci
engine originally developed for Ariane 5 ME. Vinci will produce about 18.35 tonnes
of thrust. Both stages will be 4.6 meters diameter, smaller than the 5.4 meter
diameter Ariane 5 tanks. Early concepts called for a 5.4 meter diameter second
Two to four monolithic solid rocket motors would power Ariane 6
off its launch pad. Each P120 composite-case motor would be loaded with about 120
tonnes of propellant and produce about 357 tonnes of thrust. The P120 solid rocket
motors would be common with Vega-C, a planned evolution of the current Vega launcher.
Each P120 booster would be about 3.022 meters in diameter and 17.74 meters
Ariane 6 Will Stand 20 Meters Taller than Ariane 5
An Ariane 6-2 variant would use two of the motors to lift up to 5
tonnes to geosynchronous transfer orbit (GTO) for a predicted launch cost of $97
million. It would primarily handle single-satellite government missions. An
Ariane 6-4 version would use four of the motors to lift 10.5 to 11 tonnes to GTO for about
$140 million, enough capability to handle two satellites at once like Ariane 5 ECA.
With seperate bulkhead propellant tanks and a long interstage to
allow Vinci to use a fixed nozzle extension, Ariane 6 could end up standing up to 70
meters tall, about 20 meters taller than Ariane 5 ECA. Ariane 6-2 would weigh about
500 tonnes at liftoff while Ariane 6-4 would weigh 800 tonnes.
The new Ariane 6 will require an all-new launch complex, which will
include a 100 meter tall vertical assembly building. The new launch complex was
expected to cost more than $850 million. The entire Ariane 6 development effort was
expected to cost nearly $5 billion.
Concept for Ariane 6
During November, 2012, a European Space Agency Council approved
funding both for Ariane 5 ME (Midlife Extension) development and for detailed definition
studies of a new launcher named Ariane 6. Plans called for Ariane 6 to use as many
elements as possible from Ariane 5 ME. Both efforts were funded for two years.
A final decision on the continuation of both launchers would be made in 2014.
Ariane 5 ME improves existing Ariane 5 ECA performance by using
an improved second stage that will be powered by the restartable Vinci liquid
hydrogen/oxygen engine. The upgraded rocket will lift up to 12 tonnes to GTO, with a
maiden flight expected to occur in 2017 or 2018. The Ariane 5 ME approval was a win
for Germany's Ariane 5 prime contractor Astrium. The development effort is expected
to cost 1.4 billion ($1.8 billion).
Like its Ariane predecessors, Ariane 5 ME is designed to carry
two satellites on each GTO mission. Ariancespace has found it more and more
difficult to match payloads for such missions. Ariane 6, as a result, was conceived
by French space agency CNES as a rocket optimized to launch one satellite at a time for
the least amount of money.
A critical factor in the design was the likely range of future
communication satellite weights, which initial studies determined could range from 2 to 8
tonnes with most payloads in the 3 to 6.5 tonne range.
Concept for Ariane 6
CNES studied a variety of Ariane 6 alternatives, including some
early concepts that used the Ariane 5 core but with smaller, less expensive monolithic
solid boosters, but studies eventually settled on three potential options. All three
options would use the 5.4 meter diameter Vinci powered upper stage from Ariane 5 ME and a
5.4 meter diameter payload fairing. Variantions involved the lower stage
combinations. Two options used solid motors while a third used a liquid first stage
with solid strap-on boosters.
The liquid alternative, dubbed H2C, would use zero to six solid
P33 ("P" for solid, "33" for the propellant tonnes) strap-on boosters
to augment an H165 core stage ("H" means hydrogen and "165" refers to
the tonnes of propellant carried) powered by two 150 tonne thrust engines derived from
Ariane 5's existing Vulcain 2 main engine. The Vinci powered second stage would
weigh 31 tonnes. H2C would lift up to 8.4 tonnes to GTO with six boosters, or 2.2,
5.6, and 6.7 tonnes for zero, two, or four boosters respectfully.
The first solid motor option, named P1B, would use two 3.7 meter
diameter solid motor stages, augmented by strap on solid motors, topped by the Vinci upper
stage. All of the solid motors would be monolithic (no motor segments) to cut costs
and would use composite cases to improve propellant mass ratios. The P180 first
stage (180 tonnes of propellant) would be topped by a P110 second stage. A varying
number of P39 strap on boosters would provide a range of payload capabilities. The
boosters would likely consist of sets of ground and air ignited motors. The
ground-lit boosters would be jettisonned upon burnout. P1B would be able to lift 8.1
tonnes to GTO with six boosters, or 2.1, 5.0, and 6.5 tonnes for zero, two, or four
Ariane 5 ME and Ariane 6 P7C Comparison
A second solid motor alternative was P7C. Rather than the
three varying types of solid motors used by P1B, P7C would use combinations of only one
type of solid motor. One 3.7 meter diameter P135 motor would serve as the rocket's
second stage. Two or three P135 motors would be combined to work as a first stage,
with all of the motors firing and separating together. Although promising lower
costs, P7C was also more limited since its two variants could carry a maximum of either
3.4 tonnes or 6.5 tonnes to GTO.
One advantage of the P7C is that its "smaller" P135
motors (which would still be the world's largest monolithic solid motors) might offer a
path to upgrade Vega, Europe's small all-solid launch vehicle. Vega's current first
stage is a P80 monolithic, which is currently the world's largest non-segmented solid
CNES favored the solid motor designs, which its studies showed
offered better cost competitiveness than the cryogenic core design. The improved
Vulcain 2 engine development effort would have been costly, as would have been use of two
of the engines on each flight.
At the end of January, 2013, Astrium announced that it had won an
Ariane 6 design contract. The company would perform initial definition and
feasibility studies for the future Ariane 6, aiming to pin down the launcher's primary
specifications. Astrium would study the "PPH" (solid-solid-liquid
hydrogen) design alternatives capable of lifting 3 to 6.5 tonnes to GTO. An
important design goal was a per-launch price of 70 million Euros.
Ariane 62 Design (ESA)
The CNES "Multi-P" design remained controversial
outside France. In July 2014, Airbus-Safran announced a joint venture that proposed
an alternative Ariane 6 design. It used two liquid hydrogen stages boosted by two
monolithic solid rocket motors. Unlike earlier cryogenic core designs, the first
stage was powered only by a single Vulcain 2 engine. An Ariane 6-1 "Heavy"
version would use the 5.4 meter diameter Vinci powered upper stage from Ariane 5 ME to
lift up to 8.5 tonnes to GTO. An Ariane 6-2 variant would use the ES/Aestus
engine-powered hypergolic second stage to handle Soyuz-class "Medium"
payloads. The rocket would use the existing Ariane 5 launch pad, with modifications.
By early October, 2014, the Airbus-Safran design had been further revised with the
involvement of ESA to cut costs. The hypergolic upper stage was eliminated, leaving
only the Vinci powered upper stage. Two variants were instead created by varying the
number of solid rocket motors, which were reportedly "P120" motors loaded with
120 tonnes of propellant. An Ariane 6-2 version would use two of the motors to lift
up to 5 tonnes to GTO for a predicted launch cost of $95 million. It would mostly
handle single-satellite missions. The Ariane 6-4 version would use four of the
motors to lift 11 tonnes to GTO for about $117 million, enough capability to handle two
satellites at once like Ariane 5 ECA.
The P120 solid rocket motors would be common with Vega-C, a
planned evolution of the current Vega launcher.
The modified Airbus-Safran design would use a 4.6 meter diameter
first stage loaded with 149 tonnes of propellant. Each P120 booster would be about
3.022 meters in diameter and 17.74 meters long. The entire rocket would stand about
63 meters tall, more than 5 meters taller than Ariane 5.
The resulting joint ESA-industry proposal for Ariane 6 was
presented to the Council at Ministerial level in December 2014. The Council was
expected to choose between accelerated Ariane 6 development and continued Ariane 5 ME
development at that time. A complication that arose was that the new Ariane 6 design
would not be able to use the existing Ariane 5 ELA 3 launch site, requiring the costly
development of a new facility. Development costs for Ariane 6-2 were, as a result,
projected to rise to $5.2 billion.
Design Evolves in 2015
Ariane 64 Design as of November 2015
In early November, 2015, Airbus-Safran released drawings that
showed a fatter, shorter Ariane 6. The core diameter had increased to 5.4 meters,
the same diameter as the payload fairing and the same as Ariane 5. The fatter
core had reduced overall vehicle height to 60 meters, which would make it only slightly
taller than Ariane 5. A single Vulcain V2.1 was identified as the core stage
The strap on solid rocket motors were identified as P120C motors.
Their nose fairings were elongated and they tapered in toward the core stage
intertank section, another change from earlier plans.
Liftoff mass for Ariane 62 was given as "~500 tonnes"
and for Ariane 64 as "~800 tonnes".