Its developers headed by V. M. Chelomey used the UR 500 two-stage launch vehicle as the baseline design.
Proton K, a heavy launch vehicle, is the heart of the space transportation system of Russia . It is widely used for commercial launches of foreign spacecraft and is now the main launcher used by the Russian party within the framework of the International Space Station Project. Proton K is distinguished for its high reliability, a perfect design and good performance. Subject to a decree by the Russian government, all commercial launches of Proton LVs are performed under the umbrella of International Launch Services (ILS), a Russian— U.S. joint venture.
Proton K Performance Data
|Lift-off mass (kg)||About 700,000|
|Payload mass (kg)|
|– Parking orbit ( H circ = 200 km, i = 51.6 ° )||20,700 to 20,900|
|– GTO ( i = 25 ° , H p = 5500 km) (Breeze M)||5,0 т|
|– GSO ( H circ = 35,786 km, i = 0 ° ) (Breeze M/KVRB)||2,6 (DM)|
|Parking orbit injection error||D Hp = ± 6 km
D Ha = ± 15 km
D i = ± 1.5 ang. min
D Т = ± 8 sec
|Types/quantities/thrust (sea level/vacuum) of engines|
|– Stage 1||RD 259 liquid engines/6 ea./ (971,400 kgf / 1069,800 kgf)|
|– Stage 2||RD 0210 liquid engines/3 ea. & RD 0211 /1 ea./ (- / 237,400 kgf)|
|– Stage 3||RD 0213 liquid engine/1 ea./ ( – / 59,360 kgf ) (main)RD 0214 liquid engine/1 ea./( -/ 3150 kgf) (steering)|
|PLF diameter/length (m)||3.7 / 9.83 (designed by NPO PM)3.9 / 7.647 (Block DM)3.9 / 8.897 (Block DM)4.35 / 10 (Block DM)
4.35 / 11.6 (Breeze M)
4.35 / 12.65 (LEO module)
|LV reliability||0.981 (as of early 2002)|
|Starting date of flight tests||1967|
Proton K is a heavy launch vehicle. Its developers headed by V. M. Chelomey used the UR 500 two-stage launch vehicle as the baseline design. Proton is made up of Stages 1 through 3 boosters and a space head (otherwise known as the Ascent Unit).
All stages are chained into a tandem configuration. Stages 1 and 2 are separated in a fire-and-hold mode while Stages 2 and 3 are separated in a ‘semi-hot’ mode.
Installed on each booster stage are high-efficiency main engines using high- pr essure combustion chambers, turbopump feeding, and afterburning. The development of the Stage 1 liquid pr opellant engine was managed by V. Glushko whereas Stages 2/3 liquid- pr opellant engine pr ojects were headed by S. Kosberg . Each of these engines makes use of high-boiling pr opellants, more specifically nitrogen tetraoxide (NTO) as the oxidizer and unsymmetrical dimethyl hydrazine (UDMH) as the fuel.
During the powered flight of Stage 1 the launcher is steered by deviating the gimbaled main engines. The same ap pr oach is used to navigate Proton K during the powered flight of Stage 2. Unlike these two stages, a special-purpose four-chamber thruster steers Stage 3.
Proton K is fit with a stand-alone inertial navigation system ensuring a high- pr ecision injection of various payloads into their required orbits. (This system was developed by a team headed by N. Pilyugin.) The navigation system devices are housed in the equipment bay installed on Stage 3.
Stage 1 includes a core module and six strap-on modules distributed symmetrically around the core. Fairings are installed in between the aft segments of strap-on tanks to mitigate the impact of the incident airflow on gimbaled engines.
The core module is essentially a cylinder that includes a transition compartment, an oxidizer tank and an aft compartment. Cables and pneumatic/hydraulic pipes pr otected by three duct covers run along the core module.
The transition compartment is made up of a framework and a spacer. The framework couples Stages 1 and 2 together and also allows fumes to be freely ejected as the Stage 2 engines are fired. This framework is formed by a channel-shaped stiffening ring to which crossbeams are bolted. The H-shaped crossbeams are extruded from V95 aluminum. Both the stiffening ring and the crossbeams have thermal coatings. The spacer is a riveted structure including two stiffening rings and a skin. The forward stiffening ring acts as a support surface when the core module is being transported.
The oxidizer tank is a welded load-bearing structure made of AMg 6 aluminum. It consists of a smooth cylindrical skin (reinforced by stiffening rings) and two end domes. Mounted inside the tank are 12 axial baffles. Also installed in the tank are level detectors used by the tanks simultaneous depletion system and/or the fuel pr ocess monitoring system. An annular gas blast atomizer and a drain relief valve are mounted at the forward dome. The dome exterior is covered with a thermal blanket. The aft dome has six flanges to which oxidizer distribution pipelines are attached.
The core module’s aft compartment is a riveted cone made of the V95 alloy. The compartment frame is formed by stiffening rings, extruded stringers and 12 axial forged spars taking the engines’ thrust and the load generated by the launch support legs. Both the stringers and the spars are positioned at the outer surface of the structure. The spars are coupled pairwise by plates with holes to pass drain or fueling ports. Six steel launch support legs (to be used for launch vehicle installation and fastening to the pad) are mounted at the side surfaces of these plates. The aft compartment houses a tubular truss to which pr opellant distribution pipelines and an annular pr essurized gas manifold are attached. Exhaust turbo gas diluted by the oxidizer is fed from each engine into this manifold. The end face of the aft compartment is covered by a blast deflector to pr otect the structures and cable/pipe lines in this compartment from the heat effect of the engines. An automatic interface connector is mounted in the center of the aft cover. The loading lines of each stage of the launcher as well as pneumatic and electrical umbilical connectors are automatically attached to this aft connector. After all umbilical connectors get demated in the course of liftoff this automatic connector is covered by safing plugs.
All strap-on modules of Stage 1 have the same configuration including a forward compartment, a fuel tank and an aft compartment that houses an engine.
The forward compartment of each strap-on module is a riveted conic structure serving as an air drag shield for this module. The exterior of this compartment is covered by a thermally insulating material. There are manning holes to pr ovide access to the hardware inside the compartment and the forward section of this compartment is made removable.
The welded fuel tank is made of the AMg 6 alloy. It consists of a smooth sectionized cylindrical shell (reinforced by stiffening rings) and two end domes. Level detectors used by the tanks simultaneous depletion system or the fueling pr ocess monitoring system as well as four axial baffles are installed inside the tank.
The aft compartment of each strap-on module is a riveted structure formed by stiffening rings, a set of extruded stringers, two forged plates made of the AK4 alloy (used as a support base for two engine yokes), and D16-T external sheets. The compartment is covered by a thermal blanket to pr event the cabling, the pipelines and the engine subassemblies from being heated by a burning engine.
The strap-on modules are attached to the core module in five belt areas. The couplings in the two aft belts are fixed while the remaining couplings are movable. The aft belts transfer the engine thrust and the strap-on module weight to the aft compartment of the core module. The remaining belts use tongue-and-groove joints (allowing axial displacements) and pulling rods that fix the strap-on module in the radial direction. These belts take up lateral forces. Two of these belts attach the fuel tanks to the oxidizer tank while the third belt couples the upper sections of the strap-on modules’ forward compartments to the forward stiffening ring of the oxidizer tank.
The Stage 1 pr opulsion system consists of six independent RD 253 liquid cruise engines. RD 253 was developed at the OKB 456 experimental design bureau (known today as the Glushko Energomash Research and Production Corporation) by a team headed by Academician Glushko. Each engine is mounted on two yokes in the aft compartment of a strap-on module. The thrust vector is controlled by gimbaling an engine with a hydraulic actuator within 7.5 degrees. To make this possible, the engine is mounted in the yoke bearings by means of special trunnions installed near the chamber throat.
The cylinder-shaped Stage 2 of Proton K consists of a transition bay, a pr opellant compartment and an aft compartment.
The riveted transition bay couples Stages 2 and 3. The pr imary structure of this bay is formed by stiffening rings, a set of extruded stringers, and a skin. Four ducts are pr ovided in the forward section of this bay to divert fumes during start-up of the Stage 3 steering thruster. Six solid retro engines covered by air drag shields are installed in the aft section of this bay.
The pr opellant compartment is an integrated oxidizer/fuel assembly. A common intermediate bulkhead is used to reduce the compartment length. The oxidizer tank has a smooth welded three-section skin. The fuel tank skin consists of four milled wafer sections. Each dome has a spherical shape and is butt-welded to the skin via the stiffening rings.
A transverse baffle is installed in the forward section of the oxidizer tank. An oxidizer distribution pipeline runs inside the tank. This pipeline is welded to the intermediate frame directly and to the aft fuel dome via a compensation bellows. Level detectors used by the tanks simultaneous depletion system or the fueling pr ocess monitoring system are fixed inside the tanks with bracing wires.
The fuel tank is loaded via a loading pipeline used commonly by the fuel tanks of all stages. The oxidizer tank is loaded via a loading pipeline common to Stage 2 and 3. Each pipeline is extended to the aft bay of the Stage 1 core module.
The Stage 2 aft bay includes a pr imary structure (a tunic can), a load-bearing cone and a pr otective shield. The tunic can is essentially two mated parts: the forward and the aft one. The forward section is a riveted structure that includes a set of stringers, stiffening rings and a skin. The aft section is a truss whose configuration is similar to that of the Stage 1 transition compartment except that the aft section truss has no stiffening ring. The crossbeams in the aft section of the tunic can are mated to the Stage 1 truss ring by explosive bolts and guiding pins. The load-bearing cone is a riveted structure designed to support the engine truss and to transfer the main engines’ thrust to the pr opellant compartment. This cone is made up of a skin, stiffening rings and stringers. The stringers are located at the skin exterior. A blast deflector at the aft side of the compartment controls the compartment’s internal temperature.
The Stage 2 pr opulsion unit includes for similar (though independent) cruise liquid rocket engines of which three are of the RD 0210 type and one is RD 0211. The four engines were designed by a team headed by S. A. Kosberg from the Khimavtomatika Design Bureau.
Unlike RD 0210, the RD 0211 engine has tank pr essurization systems similar to those in the Stage 1 RD 253 engine, namely a fuel-tank pr essurant generator and an oxidizer-tank pr essurant mixer. Each engine is attached by trunnions to the truss so that this engine can be deviated within 3.25 ° by a hydraulic actuator.
The Stage 3 cylindrical booster includes an equipment bay, a pr opellant compartment and an aft compartment.
The riveted equipment bay has a shell reinforced by rings and strings. The boxes accommodating the navigation and targeting system are mounted at stiffening rings. Access holes are pr ovided to service the avionics.
The aft compartment (also a riveted structure) houses a four-chamber thruster and supports four solid retro-fire rockets. The structure is made up of a shell, two interface rings and a set of stringers. Stage 2 is mated to the Stage 3 aft compartment by explosive bolts and guiding pins.
The configuration of the pr opellant compartment is similar to the tank cluster in Stage 2. The only difference is that the oxidizer tank in this case has no cylindrical section and is formed by a common bulkhead and a forward dome attached to each other by welds along stiffening rings so that the resulting shape looks like a lens. The fuel tank shell is formed by two wafer sections welded together. The conic aft end reacts to the thrust of the main engine mounted at this structure. A transverse baffle is mounted in the forward part of the oxidizer tank. The oxidizer delivery pipe runs at an angle across the interior of the fuel tank. Also, level detectors used by the tanks simultaneous depletion system or the fueling pr ocess monitoring system are fixed inside the tanks with bracing wires.
The Stage 3 RD 0212 pr opulsion system includes an RD 0213 liquid engine as the main engine and an RD 0214 four-chamber liquid engine as a thruster. RD 0213’s configuration and operation are similar to that of RD 0210 used by Stage 2. In fact, RD 0213 is RD 0210 with a modified layout of the inlet pipes and some units.
The RD 0214 thruster is designed by a team headed by S. Kosberg and A. Konopatov from the Khimavtomatika Design Bureau. No afterburning is employed. The fuel is pumped in by a single turbopump driven by two turbines, one using an oxygen-rich gas and the other a fuel-rich gas. The turbine exhaust gas pr essurizes the tanks. The engine chambers are spaced as much as possible along the booster diameter and are gimbaled in trunnions. Electrically driven actuators can gimbal these chambers up to 45 degrees to steer the booster.
Payloads are injected by either a three-stage or a four-stage Proton K. In a three-stage-to-orbit case, the space head (otherwise known as the Assent Unit) includes the payload and a payload fairing. The payload is mated to the forward interface ring of the Stage 3 equipment bay by explosive bolts and guiding pins. The payload is separated from the spacer as the explosive bolts are fired. Then special-purpose solid retro-fire rockets slow down Stage 3.
With the four-stage-to-orbit option, the space head includes additionally an upper stage acting as the fourth stage of the launch vehicle. At pr esent, Proton K uses either the Block DM upper stage or modified versions of this device. The upper stage is placed in a special tubular spacer that is attached to Stage 3 via a short cone-shaped adapter. This adapter remains mated to Stage 3 after space head separation. A payload fairing (PLF) is installed on the forward end of the tubular spacer. Today the generic PLF is used in commercial Proton K missions. This generic PLF was first tested in the ASTRA 1F mission in A pr il 1996. The PLF is jettisoned soon after firing the Stage 3 engine. The tubular spacer is dropped following space head separation.
Standard adapters with an interface diameter of either 1194 or 1666 mm are pr ovided as part of standard launch services to mate the spacecraft to Block DM. These adapters were used in the ASTRA 1F mission (1666 mm) and the INMARSAT 3 mission (1194 mm). A special dispenser was developed and fabricated under the IRIDIUM launch services contract to accommodate and simultaneously separate as many as seven spacecraft.