The Soyuz currently
offered by Starsem is a four-stage
launch vehicle. The vehicles each consist of four boosters (first
stage), a central core (second stage),
a third stage, and the restartable Fregat
upper stage (fourth stage) . Each vehicle
also includes a payload adapter/dispenser and fairing.
Boosters
(first stage)
The four boosters
are assembled around the central core and are tapered cylinders
with the oxidizer tank in the tapered portion and the kerosene
tank in the cylindrical portion.
The booster's
RD-107A engines are powered by liquid oxygen and kerosene, the
same propellants which are used on each of the lower three stages.
Each engine has four combustion chambers and nozzles. Three-axis
flight control is carried out by aerofins (one per booster)
and movable vernier thrusters (two per booster).
Following liftoff,
the boosters burn for 118 seconds and are then discarded. The
separation time is determined by comparing the velocity with
a predefined value. Thrust is transferred through a ball joint
located at the top of the cone-shaped structure of the booster,
which is attached to the central core by two rear struts.
Central
Core (second stage)
The central core is similar in construction to the four boosters,
with a hammer-head shape to accommodate the boosters. A stiffening
ring is located at the interface between the boosters and the
core. This stage has
a RD-108A engine with four combustion chambers and nozzles and
four vernier thrusters. The verniers are used for three-axis
flight control once the boosters have separated. The core stage
nominally burns for 290 seconds.
Ignition of the
central core and boosters occurs at an intermediate level of
thrust on the launch pad 20 seconds before liftoff in order
to monitor engine health parameters before the engines are throttled
up and the vehicle leaves the pad.
Third
Stage
The third stage is linked to the central core by a latticework
structure. Ignition of the third stage's main engine occurs
approximately 2 seconds before shutdown of the central core.
The third stage engine's thrust directly separates the stage
from the central core. In between the oxidizer and fuel tanks
is an intermediate bay where avionics systems are located.
This stage uses
a RD-0110 engine with four combustion chambers and nozzles.
Four vernier nozzles provide three-axis flight control.
The third stage
engine nominally burns for 240 seconds. After engine cut-off
and separation of the fourth stage, the third stage performs
an avoidance maneuver by opening an outgassing valve in the
liquid oxygen tank.
Fregat
Upper Stage (fourth stage)
Flight qualified
in 2000, the Fregat upper stage is an autonomous and flexible
upper stage that is designed to operate as an orbital vehicle.
It extends the capability of the lower three stages of the Soyuz
vehicle to provide access to a full range of orbits (MEO, SSO,
GTO, escape). In order to provide the Fregat with high initial
reliability and to speed up the development process, several
flight-proven subsystems and components from previous spacecraft
and rockets are incorporated into the upper stage.
The upper stage
consists of 6 spherical tanks (4 for propellant, 2 for avionics)
arrayed in a circle, with trusses passing through the tanks
to provide structural support. The stage is independent from
the lower three stages, having its own guidance, navigation,
control, tracking, and telemetry systems.
The stage uses
storable propellants (UDMH/NTO) and can be restarted up to 20
times in flight, thus enabling it to carry out complex mission
profiles. It can provide the customer with 3-axis stabilization
or spin-up of their spacecraft.
Vehicle
Telemetry, Tracking, and Range Safety
For the lower
three stages of the Soyuz, launch vehicle tracking and telemetry
is provided through systems in the central core and third stages.
These two stages have their own radar transponders for ground
tracking. Individual telemetry transmitters are in each stage.
For the Fregat, two different systems provide tracking and telemetry
information from launch, independent from the systems on the
lower three stages.
Telemetry and
tracking data is downlinked to ground stations along the flight
path. This data is then transmitted to the mission control center,
where it is recorded. Near real-time data processing and plotting
is conducted to follow the flight and to determine an initial
performance assessment. Flight data is analyzed and documented
within a few hours after launch.
Payload
Accommodation
The current Soyuz
flies the S-type fairing, with external diameter of 3.715-m
and a length of 7.700-m. The Fregat upper stage is encapsulated
in the fairing with the payload and a payload adapter / dispenser.
Starsem has already
developed a series of adapters and dispensers, which may be
used directly by the customer. Starsem can also carry out development
of a new adapter or dispenser tailored to the customer's spacecraft.
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