The Rokot rocket is a Russian launch vehicle capable of delivering light and medium payloads into orbit. With the Briz-KM booster block, it displays up to 2150 kg of payload to a height of 200 km.
History of creation
What is the Rokot launch vehicle? It is based on the UR-100N intercontinental ballistic missile , also known as the SS-19 Stiletto. The development of the UR-100N began in 1970 with the goal of improving the UR-100 ICBM and creating a large aircraft capable of lifting a heavier load.
Flight tests were conducted between 1973 and 1975, and the system began to function in 1974. By 1978, a total stock of 190 missiles had been reached. An improved version, called the UR-100UTTX, was put into operation in 1979 and replaced the old models, reaching a maximum stock of 360 units.
Nuclear shield
UR-100 missiles can carry up to six independent individually guided warheads with a range of 10,000 km. They can be prepared for launch within 25 minutes at any time during a 22-year shelf life. UR-100 intercontinental ballistic missiles are still in service today.
After the end of the Cold War, at the Khrunichev GKNPCs the weapon was redesigned and equipped with modern avionics and the Breeze-KM booster block, which allowed it to be used as space launch vehicles. NPO Mashinostroenie also reconstructed the UR-100 into a launch vehicle, but without significant modifications, creating a less flexible, but cheaper apparatus for launching small payloads into low Earth orbit. In this configuration, it is known as the Arrow.
From Baikonur to Plesetsk
The first launch of the Rokot rocket was carried out on November 20, 1990 from the Baikonur Cosmodrome, Kazakhstan. The first orbital flight took place on December 26, 1994. And in 1995, the Eurockot company was formed, with the help of which the Russian Rokot launch vehicle was launched on the commercial launch market.
The company acquired 45 spacecraft. In 2000, Astrium bought a 51% stake in Eurockot. The remaining 49% is owned by the Khrunichev GKNPTS. In May 2000, the Rokot was launched from the Plesetsk Cosmodrome not from a mine, as happened at Baikonur, but from a ground transportation container.
Rocket Rocket: Characteristics
The spacecraft is a two-stage liquid-propellant launch vehicle, usually equipped with the Breeze-KM last stage, which is capable of delivering payloads weighing up to 2140 kg into low Earth orbit and 1200 kg into solar-synchronous.
The characteristics of the Rokot launch vehicle are as follows:
- height 29.15 m
- the main diameter of 2.5 m,
- starting weight 107 000 kg
- fuel - asymmetric dimethylhydrazine (heptyl) and nitrogen tetroxide.
First stage
The first stage of the Rokot light-class launch vehicle is 17.2 m long and 2.5 m in diameter. A nitrogen tetraoxide tank is located above the asymmetric dimethylhydrazine tank. Two tanks are separated by a common partition. Lifting weight - 77,200 kg, inert - 5,700 kg.
In the first stage, three RD-0233 engines and one RD-0234 are used. Their designs are similar, but in RD-0234 there is a heat exchanger supplying compressed gas to the fuel tanks to maintain the necessary pressure in them throughout the entire first phase of the flight.
All engines are with closed-loop turbopumps. Each provides 470 kilonewtons of thrust, a total of 1.870 kN or 190,700 kg. The first stage vacuum draft is 2070 kN (211.100 kg), 520 kN per engine.
Management is provided by an individual cardan suspension of each of the four engines. Operating time - 121 s.
The separation is carried out in hot mode. The second stage vernier engine is ignited before the separation stage. Special hatches direct a stream of four nozzles outward. After starting the pyrotechnic mechanism, the vernier exhaust repels the spent first stage. In addition, it is equipped with four solid rocket engines, which, after separation, are ignited to remove it to a safe distance.
Second stage
The second stage is 3.9 m long and 2.5 m in diameter. Its mass is 1500 kg plus 10.700 kg of fuel. The oxidizer tank is also located above the fuel tank and is separated from it by a common partition.
The step is equipped with engines with a closed-cycle turbopump: the main RD-0235 and four-chamber vernier RD-0236 for controlling the direction of flight.
RD-0235 has a nominal vacuum thrust of 240 kN (24,470 kg), providing a pulse for 320 s.
RD-0236 provides a traction of 15.76 kN (1,607 kg) and operates for 293 s. Each of the four engine nozzles by means of a gimbal can move along one axis, providing control of the orientation of the rocket in the second stage of flight. It also uses a hot gas supply system to create the necessary pressure in the tanks.
Upper stage
The rocket "Rokot" is equipped with an accelerating unit, which consists of three main compartments - the engine, pressurized cargo compartment and an intermediate compartment, connected to the second stage.
“Breeze-KM” has 2.6 m in length, 2.5 m in diameter and a mass of 1320 kg. A heptyl tank is located above the oxidizer tank. The latter has a conical shape and a recess to accommodate the mid-flight engine. Breeze-KM is capable of accommodating 1,665 kg of UDMH and 3310 kg of oxidizing agent. High pressure helium is used to maintain the necessary pressure in the tanks and control pneumatics.
The central part of the block consists of a tank with an oxidizing agent located above the fuel tank. Both tanks are equipped with hydraulic and pneumatic systems, as well as internal baffles to prevent liquid shocks from the walls of the structure. They have a toroidal shape with a recess in the lower part for the main motor system, which made it possible to minimize the length of the step. Below is the compartment with the main power plant and stabilization and orientation engines, and spherical tanks with helium and fuel for them. The equipment is covered with thermal insulation, which prevents excessive cooling of the fuel, which affects its viscosity and can lead to freezing of pipelines and tanks.
Instrument compartment
In the upper part of the block in an inverted truncated cone there is a compartment for equipment, consisting of frames providing the installation of various controllers, telemetry modules, batteries and communication systems. Adapters up to 2.49 m in diameter are supported.
At the bottom there is a 60 cm adapter connecting the Breeze-KM to the second stage, as well as securing the fairings.
In the booster block, two fuel systems are implemented: low pressure for the main engine and high pressure for stabilization and orientation engines. Both use asymmetric dimethylhydrazine and nitrogen tetroxide, which ignite immediately after coming into contact with each other.
Booster engines
The orientation control engines used on the Breeze-KM are called 17D58E and provide a nominal thrust of 13.3 N. Each block is 14 cm long and weighs 550 g. The micromotor operates with a mixture ratio of 1: 1.85 and the nominal input pressure of 14.7 bar, but it is able to withstand a wide range of pressures from 7.8 to 34.3 bar. To control the orientation, power plants are used in pulsed mode with a minimum operating time of 0.03 s, but the 17D58E is also certified for continuous operation for up to 10,000 seconds. The engine withstands 450,000 duty cycles.
Booster system power supply
“Breeze-KM” is equipped with its own power system, consisting of batteries and power distribution systems, which provide up to 7 hours of operation of the stage in orbit. The instrument compartment includes telemetry devices with transmitters and antennas, as well as tape recorders for storing and transmitting data. The guidance, navigation and control system is responsible for the flight at all stages. It consists of a platform with inertial guidance, including a 3-axis gyroscope with on-board computers. The system has triple redundancy with majority decision making. It is completely autonomous and cannot be controlled externally.
Cowl
The Rokot rocket is equipped with a fairing, which was specially designed for the commercial version of the spacecraft. It is mounted on the instrument compartment of the upper stage. It consists of two parts of 7.8 m in length, which together have an elliptical shape of 2.5 by 2.62 m in diameter. The payload space is 5.9 m in height.
The fairing protects the spacecraft from aerodynamic, thermal and acoustic influences exerted on it during flight in the atmosphere. When the rocket leaves it, the fairing is reset by opening mechanical locks fastening two half-shells along the vertical separation line, using a pyrotechnic device located in the nose of the fairing. Then, on a horizontal separation line, several pyro-bolts are shot off, which allows the fairing to go apart thanks to spring pushers. The hinges at the base provide rotation away from the rocket and clear separation.
System Storage and Startup
Unlike SS-19, which start from the mines, the launch of the Rokot launch vehicle is carried out from the transport and launch container at the Plesetsk cosmodrome, Russia. Missiles are stored for a long time, which requires monitoring of climatic conditions and maintaining a nitrogen atmosphere. Transportation and installation on the launch pad are also carried out in a container. In addition, the container contains equipment for pre-treatment and environmental protection.
Before starting it moves apart, and a payload, upper stage and fairing are installed on the launch vehicle. Refueling interfaces, as well as power and data cables are connected to the container. In an upright position, the Rokot rocket rests on a ring at the bottom of the container. During take-off, the burst cables are disconnected by mechanical systems. During the start, the device is guided by two rails. The container protects the launch pad from engine emissions and is used once.
Interesting Facts
The launch of the Rokot rockets will be discontinued in 2017 after the implementation of the planned federal and commercial launches.
The name SS-19 Stiletto is the NATO name for this type of ICBM. SS stands for Earth-to-Earth system, and the number 19 and the name "Stiletto" are assigned to this type of intercontinental ballistic missile. In Russia, the official name is SS-19 - RS-18 and UR-100N.
The best thing about the Rokot space rocket is its reliability, which is confirmed by 27 successful launches out of 29. And out of 150 SS-19 launches, only 3 failed at the very beginning of their operation in the 1970s. Test launches SS-19 and "Rokot" are held annually as part of the reliability check of the spacecraft and the exercises of the space forces.