Category Energiya-Buran

The RLA concept fitted well in a new philosophy to replace the existing fleet of Soviet launch vehicles by a new generation of rockets. By the early 1970s the Soviet Union was operating five basic types of fundamentally different launch vehicles each derived from a specific intermediate or intercontinental ballistic missile: the Kosmos and Tsiklon rockets (based on the R-12, R-14, and R-36 missiles of the Yangel bureau), the Vostok/Soyuz family (based on the R-7 missile of the Korolyov bureau) and the Proton (based on the UR-500 missile of the Chelomey bureau). While the R-7 based rockets used LOX/kerosene as propellants, all the others relied on storable hypergolic propellants.

Around the turn of the decade plans were being drawn up for new generations of satellites with more complex on-board equipment and longer lifetimes, requiring the use of heavier, more capable launch vehicles. By early 1973 a research program called Poisk (“Search”), conducted by the Ministry of Defense’s main space R&D institute (TsNII-50), had concluded that future satellites should be divided into four classes: “light” satellites up to 3 tons, “medium-weight” satellites up to 10-12 tons, “heavy” satellites (up to 30-35 tons), and “super-heavy” satellites (not specified). The last three classes were not served by the existing launch vehicles.

The new family of launch vehicles was to have two key characteristics. First, in order to cut costs to the maximum extent possible, it would use unified rocket stages and engines. Second, it would rely on non-toxic, ecologically clean propellants, with preference being given to liquid oxygen and kerosene. The reasoning behind this reportedly was that “the number of launches of [space rockets] would be much higher than the number of test flights of nuclear missiles with [storable] propellants.” What also may have played a role were a series of low-altitude Proton failures that had contaminated wide stretches of land at or near the Baykonur cosmodrome. The basic conclusions of the study were approved on 3 November 1973 at a meeting of GUKOS [45]. Although not stated specifically, the long-range goal of this effort seems to have been to phase out all or most of the existing missile-derived launch vehicles.

Initially, the primary focus apparently was on unifying the light to heavy class of rockets, because at the time these decisions were made super-heavy rockets and reusable shuttles were still a distant and vague goal. It would seem that three design bureaus were ordered to come up with proposals for such a family of launch vehicles under a competition called Podyom (“Lift”). Both Branch nr. 3 of TsKBEM in Kuybyshev (which became the independent TsSKB in July 1974) and Chelomey’s TsKBM put forward plans to refit their respective Soyuz and Proton launch vehicles with the Kuznetsov bureau’s LOX/kerosene NK engines originally built for the N-1 rocket. The former Yangel bureau in Dnepropetrovsk (now called KB Yuzhnoye and headed by Vladimir Utkin) also weighed the idea of using NK engines (which after all were around and had been tested), but in the end favored the new generation of LOX/ hydrocarbon engines being designed by Energomash [46].

Actually, by this time Yuzhnoye had been working for several years on a new medium-lift launch vehicle (11K77) burning storable propellants. In December 1969 it had been ordered by GUKOS to develop a new rocket capable of placing 8 tons into low polar orbits and 2 tons into highly elliptical Molniya-type orbits. The initial idea in 1970 was to build a three-stage rocket with 3.6 m diameter modules. The following year attention turned to a rocket derived from the bureau’s R-36M, a new ICBM that had been approved by a government decree in September 1969. By retaining the 3.0 m diameter of the R-36M’s rocket stages, no fundamentally new manufacturing techniques would be required. The 11K77 would now consist of a pair of R-36M first and second stages stacked on top of one another plus a newly developed third stage. In 1972 Yuzhnoye also designed a slightly less powerful rocket designated 11K66, essentially a two-stage R-36M with increased propellant load capable of orbiting 5.9 tons.

When Yuzhnoye made the switch to LOX/kerosene under the Podyom program in 1974, it opted for a vehicle maintaining the 3.0 m diameter of the rocket stages, but employing parallel staging. This version of the 11K77 would fly the single-chamber LOX/kerosene engines then being designed at Energomash. The second stage, acting as the core, would have a 130-ton thrust RD-125 engine, and the two first-stage modules flanking the core would each have three 113-ton thrust RD-124 engines. These engines had combustion chambers of roughly the same size and pressure as those of the R-36M first-stage engine. Payload capacity to low orbit was now 12 tons.

By early 1975 Energomash’s Department 728 had made enough progress on the powerful 600-ton thrust RD-123 for Yuzhnoye to incorporate it into the 11K77 design. This made it possible to replace the two modules of the 11K77’s first stage by a single module, although its diameter would have to be increased to 3.9 m, which was the maximum that could be transported by rail. The second stage would now be placed on top the first stage, turning the 11K77 into what the Russians call a “mono­block’’ booster. After a convoluted development path, the rocket had now acquired the configuration in which it later became known to the world as Zenit. It could also serve as the basis for a lighter rocket (11K55) and a heavier version (11K37), with the three covering the whole payload range from “light” to “heavy” (see Chapter 8) [47].

Being in the heavy to super-heavy class, Glushko’s RLA family was not part of the Podyom competition, but as plans for a large Soviet shuttle gained more support in 1975, so did the idea of unifying the first stage of the RLA rockets with that of the future medium-lift rocket. It is unclear if this consideration played a significant role early on in the Podyom competition. If it did, TsSKB and TsKBM had betted on the wrong horse by anticipating that whatever followed the N-1 would also carry NK engines, while Yuzhnoye had made the right choice by picking the new Energomash engines. However, the history of the 11K77/RLA unification is a complicated chicken-and-egg story, with sources differing on whether the initiative to unify the first stages came from Glushko or Utkin. At any rate, Yuzhnoye emerged as the winner of the Podyom competition in 1975, no doubt because its medium-lift rocket could now act as a test bed for the first stage of the rocket that would power the Soviet space shuttle to orbit.

The 11K77 is the only thing that ever came out of Podyom. Yuzhnoye’s proposed light-class and heavy-class rockets never flew and the whole idea of a standardized fleet of dedicated, environmentally clean space launch vehicles in the light to heavy class remained a distant dream, probably because it infringed too much on design bureau interests. In fact, most of the IRBM and ICBM-derived launch vehicles conceived in the 1960s continue to fly today, although another attempt is being made to develop a standardized rocket fleet under the Angara program (see Chapter 8).

The Energiya “Blok-A” strap-on boosters were largely designed and built by KB Yuzhnoye and its associated production facility in Dnepropetrovsk, although major elements were also supplied by NPO Energiya in Kaliningrad. Each strap-on booster was 39.4m high and had a maximum diameter of 3.9 m, dictated by railway trans­portation requirements. The wet mass was about 372 tons. The booster consisted of a nose section, an upper LOX tank, an intertank structure, a lower kerosene tank, and

a tail section with the gimbal-mounted LOX/kerosene RD-170 engine. The four boosters were numbered 10A, 20A, 30A, and 40A.

The nose section housed the avionics bay, which among other things contained an M4M computer that interacted with the core stage’s M6M central computer. Also installed in the nose section were flight data recorders, mounted in a special casing that protected them from the force of impact. Two of the four Blok-A boosters were equipped with radio beacons, enabling ground controllers to follow their trajectory after separation from the core stage.

The propellant tanks were made of an aluminum-magnesium alloy, with the walls being about 30 mm thick. The LOX and kerosene tanks had useful volumes of 208 m3 and 106 m3, respectively, holding approximately 220 tons of LOX and 80 tons of kerosene. The upper LOX tank fitted in a concave depression at the top of the kerosene tank and the LOX feed line passed right through the middle of the lower kerosene tank. There were vent and relief valves in the forward domes of both tanks. The kerosene fill and drain valves were in the aft dome of the kerosene tank, and the LOX fill and drain valves in the lower part of the LOX feed line. The LOX feed line also had a damper to suppress “pogo” oscillations.

Embedded in the lower part of the LOX tank were two rows of helium tanks for in-flight pressurization of both the LOX and kerosene tanks. The helium for the kerosene tank was supplied directly, while that for the LOX tank first passed through a heat exchanger in the lower engine compartment. Before launch the tanks were pressurized with ground-supplied helium. Electrical power for the boosters was provided by batteries.

There was a pair of strap-ons on either side of the core stage. Each pair was mechanically linked and jointly separated from the core stage, with the two boosters not splitting until about half a minute later. This was done in order to minimize the risk of any of the boosters hitting the orbiter after separation. The boosters were pyrotechnically separated from the core stage and subsequently activated 11 small solid-fuel motors (seven on the nose section and four on the tail section) to ensure safe separation from the core stage and payload. They came down some 425 km downrange from the launch site.

Although they were mechanically linked, the strap-ons operated independently from one another. The only electrical connections were with the core stage (one interface with 408 contacts for each booster). There were also twelve electrical, pneumatic, and hydraulic connections between each strap-on and the launch pad (eight for propellant, fluid, and gas supply and four electrical connections). The connections were between the nose section and the launch tower and the tail section and the launch table.

From the very beginning of the Energiya-Buran program the idea was that the strap-on boosters would be reusable. The degree of reusability mainly depended on the robustness of the RD-170 engine, which was certified to fly at least 10 missions. After having studied several schemes, designers opted for a horizontal landing system using parachutes, soft-landing engines, and a set of shock absorbers. Parachutes would be deployed from the forward and aft ends of each booster, orienting it to a horizontal attitude for descent. The plan had much in common with the landing

technique for the giant MTKVP lifting body that had been studied before the delta­wing concept of Buran was picked.

The strap-ons were designed from the beginning with special containers in their nose and tail sections to house the parachutes, other recovery systems, and control equipment. The containers were installed on the strap-ons flown on the two Energiya missions in 1987 and 1988 (6SL and 1L), but were loaded with instrumentation rather than recovery equipment. However, there were plans to demonstrate the recovery technique on the 2L mission with the GK-199 payload (see Chapter 8).

The boosters shared about 70 percent of their systems with the first stage of the Zenit rocket. The part of the booster that was largely similar to the Zenit first stage was known as the “modular part” (or 11S25) and included the propellant tanks, pressurization systems, and the engine compartment. The main differences with the Zenit first stage were in the gimbal axes of the engines and also in that the tank walls were slightly thicker because of the bending loads imposed by the strap-on config­uration. Elements unique to the strap-ons included the aft skirt surrounding the engine compartment (which needed to be compatible with the Energiya core stage), the entire nose section, and the parachute containers.

The original requirement was for the Zenit first stage to be reusable as well, but, if it was to use the same recovery systems and recovery zones as the Blok-A, the Zenit would need to have the same speed at the moment of first-stage separation as Energiya (1,800 m/s instead of 2,500 m/s). This would have made it necessary to make the second stage 38 tons heavier, reducing the rocket’s payload capacity to

an unacceptable 7 tons. A later idea to recover only the tail section with the engine was dropped as well because this was expected to produce a return on investment after only about 500 launches [3].

The Electric Power System (SEP) supplied power to Buran’s systems during the final countdown, the mission itself, and during initial post-landing servicing. As on the Shuttle Orbiter, electricity was to be generated with the help of fuel cells (“electro­chemical generators’’ in Russian terminology) using cryogenically stored oxygen and hydrogen reactants. Whereas NASA introduced fuel cells back in the Gemini program, the Russians had always used battery systems and/or solar panels on Vostok, Voskhod, and Soyuz. They did develop a fuel cell system called Volga-20 for the Soyuz-based LOK lunar orbiting ship to be used in the N-1/L-3 manned lunar-landing program, but the only LOK ever flown was lost in the fourth and final launch failure of the N-1.

The SEP consisted of the Oxygen/Hydrogen Cryostats, a Power Module, an Instrument Module, and the Distribution and Commutation System. The first three subsystems were situated in the mid fuselage under the front section of the payload bay, so that receding fuel levels in the cryogenic tanks would not affect Buran’s center of gravity. Although the oxygen and hydrogen were delivered to the fuel cells in gaseous form at a temperature of about 10° C, they were stored cryogenically to save mass. Buran could accommodate two oxygen and two hydrogen tanks, which needed to be filled in the final days before launch via 500 x 600 mm doors in the mid fuselage.

The oxygen and hydrogen were fed to the Power Module, which contained the actual fuel cells. There were a total of four fuel cell units (as compared with three on the Shuttle Orbiter), each consisting of eight 32-cell stacks connected in parallel and with an active electrode area of 176 m2. The alkaline fuel cells used a potassium hydroxide electrolyte immobilized in an asbestos matrix and had an oxygen electrode (cathode) and a hydrogen electrode (anode). Each fuel cell unit provided 10 kW continuous and 25 kW peak at between 29 and 34 volts of direct current. Only three

sets of fuel cells were needed for a nominal mission and two for an emergency landing.

The Instrument Module turned the fuel cells on and off and automatically controlled all processes taking place in the system. In case it detected an anomaly, the crew was notified of this on the control panels in the cockpit and with a master alarm. Although the fuel cells were designed to operate entirely automatically, they could also be controlled by the crew or from the ground. Power was distributed to all parts of the vehicle by the Distribution and Commutation System, which consisted of two redundant subsystems, one running along the starboard side, and the other along the port side.

The fuel cells produced water as a byproduct (more than 100 kg per day) for consumption by the crew and also for use in the flash evaporators of the Thermal Control System and the hydraulic system. The liquid oxygen stored in the SEP tanks could also be turned into gaseous oxygen for the crew compartment.

For extended missions, Buran could carry a “cryo kit” located near the middle of the payload bay and equipped with up to six liquid hydrogen tanks. During a long mission the fuel cells would first use the hydrogen supply from the cryo kit before switching to the standard LH2 tanks under the payload bay. Extra oxygen would be drawn from the LOX tank of Buran’s propulsion system situated in the aft fuselage. Buran’s cryo kit was comparable with that developed for the Shuttle’s Extended Duration Orbiter missions, although that was to be mounted in the aft payload bay and had both liquid hydrogen and liquid oxygen tanks (given the use of storable rather than cyrogenic propellants in the on-orbit propulsion system).

In addition to the fuel cells, Buran also had battery packs that were charged by the fuel cells and fed electricity to various power-hungry systems, mainly in the aft fuselage. For the first multi-day test flights it was also planned to fly battery packs operating independently from the fuel cells to give one day of back-up power in case of a fuel cell failure, enough to make an emergency return to Earth. Since Buran’s one and only mission lasted just several hours, the fuel cells were not installed, with the vehicle’s systems drawing power from batteries in the BDP payload stowed in the payload bay (see Chapter 7). Fuel cells were installed on the second vehicle and underwent loading tests at the launch pad.

Called Foton (“Photon’’), Buran’s fuel cells were developed jointly by NPO Energiya and the Ural Electrochemical Integrated Factory in Verkh-Neyvinsk (Sverdlovsk region), which had also developed the Volga-20 fuel cells for the LOK back in the early 1970s. Although never actually flown in space, the Buran fuel cells attracted the interest of the European Space Agency, which tested a Buran flight – model fuel cell in 1993 at the facilities of ESTEC in Noordwijk, Holland as part of studies to incorporate foreign technology into the Hermes spaceplane. A modified version of Foton powered the first Russian fuel cell car, the Niva, presented at a Moscow auto show in 2001. RKK Energiya is also considering a Foton-derived fuel cell system for its new Kliper spacecraft [20].

The single mission flown by Buran on 15 November 1988 was not a standard flight. It was flown without a crew on board and with the sole intention of testing the launch and re-entry procedures. No major on-orbit tasks were scheduled and Buran flew without many of the systems that would have been required for a multi-day manned mission. What will be described here are the standard launch and landing procedures and standard on-orbit operations for operational missions with a crew on board. Details of actually planned missions will be given in Chapter 8.

Launch

The launch began with the ignition of the core stage’s four RD-0120 engines at T — 9.9 seconds, followed at T — 3.7 seconds by the ignition of the strap-on rockets’ RD-170 engines. The interval was required to allow the core stage engines to slowly build up thrust and thereby ease the acoustic loads on the orbiter. If an anomaly was detected by the rocket’s flight control system, all engines could be shut down at any moment prior to T — zero.

As the stack cleared the tower, it performed a pitch and roll maneuver to place it in the proper attitude for the remainder of the ascent. About half a minute into the flight the core stage and strap-on engines were throttled back to minimize aero­dynamic pressures and longitudinal loads on the vehicle. After passing through the densest layers of the atmosphere, all engines were throttled back up to nominal thrust, although the Blok-A RD-170 engines were soon again throttled down in preparation for shutdown. The four strap-on boosters shut down in pairs with an interval of 0.15 seconds and were jettisoned about two seconds later at T + 2m26s. They continued to fly in pairs, separating from one another somewhat later to come down some 425 km downrange. As mentioned earlier, the strap-ons could land on parachutes for recovery but were not configured as such on the two Energiya launches that were flown.

Moving on downrange, the core stage again began throttling down its four liquid oxygen/liquid hydrogen engines less than a minute before shutdown, which occurred at T + 7m47s. The engines were shut down in pairs with an interval of 0.2 seconds. Fifteen seconds later the orbiter separated from the core stage and safely maneuvered itself away with gentle burns of its primary thrusters. The core stage then continued on a ballistic trajectory to burn up over the Pacific Ocean. Not having required orbital velocity yet, Buran then needed two burns of one of its DOM engines about 11 and 40 minutes into the flight to place itself into an initial orbit. The required burn duration was calculated by the on-board computers on the basis of the launch vehicle’s performance. The maximum acceleration forces for the crew during launch would not have exceeded 3g.

The crew had no active role to play during the launch phase and merely had to monitor the operation of on-board systems on their cockpit displays. The orbiter’s computers automatically controlled the operation of the life support, thermal con­trol, power, and monitoring systems as well as that of the hydraulic systems and Auxiliary Power Units, which might be needed in a launch abort to perform an emergency landing. They also opened and closed the vehicle’s vent doors at the required moments [28].

The Energiya core stage’s RD-0120 engines were designed by the Design Bureau of Chemical Automatics (KB Khimavtomatiki or KBKhA) in Voronezh. This bureau was founded in 1941 by Semyon A. Kosberg in the city of Berdsk and was transferred to Voronezh as OKB-154 in 1946. Kosberg headed the bureau until he was killed in an automobile accident in 1965 and replaced by Aleksandr D. Konopatov, who remained in charge of the bureau until 1993. The bureau developed engines for surface-to-air missiles, submarine-launched and intercontinental ballistic missiles, and entered the space business in the late 1950s with the development of upper-stage engines for R-7 derived launch vehicles. It also designed the second and third-stage engines for the Proton rocket. KBKhA was a newcomer to the development of cryogenic engines when it was assigned to develop the RD-0120. Chief designer of the RD-0120 was Vladimir S. Rachuk, who would go on to become the general designer of KBKhA in 1993.

Actual manufacturing of the RD-0120 engines took place at the Voronezh Machine Building Factory (VMZ), located on the same premises as KBKhA.

Founded in 1928, VMZ switched to the production of rocket engines in 1957, building all the engines designed at KBKhA [5].

Describing the history of the Buran cosmonaut team is not as straightforward as it may seem at first glance. Unlike the situation in the US, where NASA has always been in charge of selecting and training the (career) astronauts that make up Space Shuttle crews, the Soviet Union’s space program lacked a central coordinating NASA-type organization. Several organizations involved in test pilot and cosmonaut training felt they should all independently select their own cosmonaut teams. From these groups, Buran crew members representing those organizations would be assigned.

Three organizations selected cosmonauts specifically for Buran:

• The Cosmonaut Training Center named after Yu. A. Gagarin (TsPK for Tsentr Podgotovki Kosmonavtov) based in Star City (Zvyozdnyy Gorodok) near Moscow.

This Soviet Air Force unit, set up in I960, had been in charge of selecting and training cosmonauts for flights on Vostok, Voskhod, Soyuz, and Salyut.

• The Flight Research Institute named after M. M. Gromov (LII for Lyotno – Issledovatelskiy Institut) in Zhukovskiy, some 35 km southeast of Moscow.

The Flight Research Institute, a civilian research and development entity subordinate to the Ministry of the Aviation Industry (MAP), was founded in 1941 as the leading test center for experimental and production aircraft. LII had a Test Pilot School (ShLI).

• The State Red Banner Scientific Test Institute named after V. P. Chkalov (GKNII for Gosudarstvennyy Krasnoznamennyy Nauchno-Ispytatelnyy Institut) in Akhtubinsk, some 130 km west of Volgograd and about 50 km south of the Kapustin Yar cosmodrome in the Volga delta.

This Air Force unit was set up in 1960 at the same site that had served since 1947 for testing various unmanned flying apparatuses, such as surface-to-surface missiles, air-to-surface missiles, and the Burya intercontinental cruise missile.

The site was sometimes referred to as Vladimirovka, after a nearby railway station. With the establishment of GKNII its role was expanded to testing various aircraft for the Air Force and it also included an Air Force test pilot school known as the Test Pilot Training Center (TsPLI).

In March 1979 MOM, MAP, and the Ministry of Defense jointly decided that a pool of 17 pilots would be required for the Buran test flight program: six from LII, six from GKNII, and five from TsPK [1]. Part of the reason for assigning pilots from three different organizations was no doubt the departmentalism typical of the Soviet space program. However, there appear to have been more rational considerations as well. Since Buran was far more complex than any Soviet spacecraft flown before, the unmatched flying skills of the LII pilots were probably considered necessary to safely guide the vehicle through its initial atmospheric and orbital flight tests, with GKNII becoming involved in the test flights at a somewhat later stage. It was not uncommon in the former Soviet Union for the Air Force team in Akhtubinsk to further test new aircraft once they had been declared airworthy by the LII pilots, and in this respect Buran was no exception [2]. Presumably, the LII pilots were to fly test flights with civilian payloads, and the GKNII pilots test flights with military payloads.

Once their job was completed, these career test pilots would then return to their usual line of work, passing the torch to the “regular” TsPK pilots to finish the test program, and ultimately fly Buran’s operational missions. This, at least, appears to have been the original intention when the first pilot teams were selected in the 1970s and Buran was expected to begin flying in the first half of the 1980s. As the orbital test flights slipped into the late 1980s and were spread out over many years, the opera­tional phase became a distant and vague goal. Therefore, in the end the only pilots seriously considered to fly on Buran were from LII and GKNII, and further TsPK selections were solely aimed at the mainstream Salyut/Mir space station program.

In addition to the pilots, engineers from both NPO Energiya and the Air Force were assigned to Buran as well, although none of them ever appear to have been specifically selected for the program. Because of all this, it is not possible to really give one single founding date for the Buran cosmonaut team.

Before the beginning of the Energiya-Buran program the only liquid oxygen/liquid hydrogen engines developed in the Soviet Union had been the 7.5-ton thrust 11D56 of KB Khimmash and the 40-ton thrust 11D54 and 11D57 of KB Saturn, intended to be used on upper stages of the N-1 rocket. Therefore, the development of the 190-ton thrust RD-0120 for Energiya’s core stage, assigned to KBKhA in Voronezh, was a major challenge, partly because much of the infrastructure needed for testing the engine was not yet in place. This required a step-by-step approach to certifying the engine for flight. The first step was to test individual components of the engine, followed by test firings of experimental engines at increasing rates of thrust, and ultimately test firings of flightworthy engines both individually and mounted in clusters of four on Energiya’s core stage at Baykonur’s UKSS pad.

Since the RD-0120 was the first powerful Soviet cryogenic engine, many com­ponents that would usually be installed straightaway in experimental engines now had to be tested individually first. Particular attention was paid to the ignition system in the combustion chamber and the gas generator as well as to the operation of the low-pressure turbopumps. The components for these tests were built both by KBKhA’s own Experimental Factory and by the Voronezh Machine Building

Factory and tested at various locations in the Soviet Union, including KBKhA’s own experimental base in Voronezh.

While KBKhA had its own rocket engine test stands near Voronezh, none of these could be converted for test firings of this radically new engine, nor was it deemed expedient to build the new facilities there. Instead, test firing stands for the RD-0120 were built by two other organizations. One was the Scientific Research Institute of Machine Building (NII Mashinostroyeniya or NIIMash) in Nizhnyaya Salda north of Yekaterinburg. This organization had become independent in 1981 after having been a branch of the Scientific Research Institute of Thermal Processes (NII TP), which was how the former NII-1 was renamed in 1965 (in 1995 it was again renamed as the Keldysh Research Centre). NIIMash mainly specialized in reaction control thrusters for satellites and manned spacecraft (including Buran).

NIIMash had two test stands (nrs. 201 and 301) for firing the RD-0120 in vertical position. Construction got underway in 1977 and 1981, respectively. The test stands allowed the engines to be gimbaled and had diffusers to simulate operating conditions at higher altitudes. Stand nr. 301 was capable of handling longer duration test firings (over 1,000 seconds) and maximum gimbal angles. RD-0120 engines were delivered to Nizhnyaya Salda from the manufacturing plant in Voronezh by Antonov-8 cargo planes.

The other organization was NIIkhimmash near Zagorsk. It had a cryogenic complex called KVKS-106, already used before the Energiya-Buran program for testing the 11D56 and 11D57 cryogenic engines. KVKS-106 comprised five test facilities, one of which had two test stands (V-2A and V-2B) for full-scale test firings of the RD-0120 in horizontal position. Others were used to test individual components of the engine and the core stage. The engines were transported from Voronezh to NIIkhimmash by road.

The bulk of the testing was to be carried out at Nizhnyaya Salda, but, as the construction of the facilities there ran into delays, it was decided to test the first engines at the existing cryogenic complex of NIIkhimmash. The first test engine (with

a shorter-than-nominal nozzle) was delivered to Nllkhimmash in the autumn of 1978 and underwent a first brief test firing (4.58 seconds) at the V-2B stand in March 1979. The initial tests at Nllkhimmash were conducted at just 25 percent of rated thrust, but allowed to test such things as the ignition and shutdown sequence. The adjacent V-2A, capable of supporting tests at 100 percent thrust, was ready in 1984.

The first test firing at NIIMash’s test stand nr. 201 took place on 19 January 1980, also at low thrust. By early 1981 the engine was being tested at 70 percent thrust, and it wasn’t until May 1984 that the RD-0120 worked at 100 percent thrust for 600 seconds (with the nominal operating time during launch being 467 seconds). Considerable delays in reaching nominal thrust were caused by problems with the impeller of the liquid hydrogen pump, a rotating disk with a set of vanes that produces centrifugal force within the pump casing. The problem was eventually solved by using a different type of titanium to manufacture the component.

Although the RD-0120 test program took longer than expected, it does not appear to have been a major factor in the delays of Energiya’s first launch. By the time of that maiden launch in May 1987 the Russians had accomplished 523 test firings of 103 different RD-0120 engines with a total duration of 73,891 seconds. NIIMash’s test stand nr. 301 saw its first test firing on 30 July 1987. Records set during that same period were a 100-second test at 123 percent rated thrust in September 1987 and a maximum-duration burn of 1,202 seconds in January 1988. By early October 1988, about a month before the maiden flight of Buran, a total of 126 engines had undergone 635 test firings lasting a total of 120,454 seconds. By comparison, NASA accumulated 110,253 seconds of burn time on the Space Shuttle Main Engines in 726 test firings before STS-1.

The RD-0120 test program continued at Nllkhimmash even after the cancella­tion of the Energiya-Buran program under a deal between KBKhA and the US Aerojet company to study the feasibility of using the engine on future American launch vehicles. Several test firings were also performed in the mid-1990s in the framework of the joint European-Russian RECORD program (Russia-Europe Cooperation on Rocket Engine Demonstration), led by the French SEP company. In those tests, the engine was equipped with European instrumentation to allow European engineers to create a detailed software model of the engine and gain experience with staged-combustion cycle cryogenic engines for possible use in future reusable systems. The final test firing of the RD-0120 was conducted at Nllkhimmash in 1997. The maximum accumulated test time for a single engine was about 5,000 seconds and the maximum number of ignitions for a single engine was thirty [2].

A typical BOR-4 mission would begin with a launch from the Kapustin Yar cosmo­drome near Volgograd using a modified two-stage Kosmos-3M booster known as K65M-RB5. Baykonur no longer supported that rocket at the time and although Plesetsk did it was situated too far north to place the spaceplane models into the proper inclination. The rockets used for the BOR-4 missions had originally been earmarked for other missions, but had already exceeded their guaranteed “shelf life’’ and would have been used for test launches anyway.

The vehicle would be launched with its two wings completely folded so that it fitted under the rocket’s fairing. After release from the launch vehicle, the wings were unfolded to a position that would keep the vehicle stable during re-entry at an angle of attack of between 52° and 57° between altitudes of 70 and 60 km. Orientation in orbit was carried out with the help of eight microthrusters burning hypergolic propellants. After a single revolution of the Earth, BOR-4 initiated its descent back to Earth, firing what is believed to have been a jettisonable solid-fuel motor mounted on top of the vehicle. At an altitude of 30 km the on-board control system sent BOR-4 on a steep spiralling trajectory to decrease speed and at 7.5 km the spacecraft deployed a parachute that reduced the vertical landing speed to 7-8 m/s.

Since the vehicle was not equipped with landing gear, it needed to land on water to ensure that its heat shield remained intact for post-flight analysis. The only major bodies of water on Soviet territory that would be in the BOR’s flight path were the Black Sea and Lake Balkhash. However, the Russians had never returned a winged vehicle or lifting body from orbit and were not confident they could aim the space­craft for precision splashdowns in the Soviet Union. Therefore they opted to land the first vehicles in the Indian Ocean, where they would still come down in water even if they fell short of or overshot the planned landing area. That did, however, signifi­cantly increase the cost of the recovery operations, which, moreover, would be hard to conceal from the prying eyes of Western reconnaissance aircraft.

After splashdown a conically shaped float was inflated on top of the spacecraft to improve its buoyancy. The float also had flashing lights and antennae to make it easier for the recovery forces to locate the BOR. Before being hoisted on board a recovery ship, a crew was sent out to the vehicle to disarm an on-board self-destruct system.

While BOR-4 was designed in Zhukovskiy under the leadership of LII chief Viktor V. Utkin, the vehicle was manufactured and covered with heat-resistant materials at the Tushino Machine Building Factory. The man in charge of the BOR-4 program at NPO Molniya was Stepan A. Mikoyan, a deputy of chief designer Gleb Lozino-Lozinskiy. The BOR-4 test flights were coordinated by a State Commis­sion headed by former cosmonaut Gherman Titov, then serving as a deputy head of GUKOS. Titov, incidentally, had also been part of the Spiral cosmonaut training group at Star City in the 1960s.

The orbital flights were preceded by an experimental suborbital launch on 5 December 1980 in the direction of Lake Balkhash. This mission was intended to test the rocket, the aerodynamic characteristics of the vehicle, and the performance of the aerodynamic surfaces and rocket thrusters. Designated BOR-4S (serial nr. 401), the vehicle only had the original ablative heat shield. The final part of the flight was monitored by two Ilyushin 18RT aircraft flying in the vicinity of Lake Balkhash. These were modified Ilyushin 18D aircraft specially adapted to perform tracking in areas that were not covered by Soviet ground-based or sea-based tracking means.

In the spring of 1982 seven Soviet ships set sail for the Indian Ocean to support the first orbital mission of a BOR-4 vehicle. These included two vessels to ensure communications between the fleet and the home front, namely the Navy’s Chumikan and the Academy of Sciences’ Kosmonavt Georgiy Dobrovolskiy. In no time Royal Australian Air Force P-3C Orion reconnaissance aircraft deployed from RAAF Base Williams in Point Cook were circling overhead to monitor the vessels’ activities.

Finally, on 3 June 1982 the first BOR-4 covered with Buran’s heat shield materials (serial nr. 404) was successfully placed into orbit. After a single orbit the vehicle fired its deorbit engine and re-entered the Earth’s atmosphere, performing a cross-range maneuver that took it about 600 km to the south of its orbital path. The craft gently splashed down some 560 km south of the Cocos Islands, which was about 200 km from its intended landing point. The recovery operation was seriously hampered by stormy seas. Battling high waves, recovery forces on board the vessel Yamal needed several attempts to hoist the BOR-4 on deck. During one of those

attempts, the vehicle accidentally bumped into the Yamal, causing significant damage to the spacecraft’s nose section. The entire operation was photographed by an Australian Orion aircraft, which according to Russian eyewitnesses flew so low that the slipstream nearly knocked them off their feet.

The TASS news agency issued a routine statement saying a satellite called Kosmos-1374 had been launched for “the further study of outer space’’, providing no hint of its real mission. It only differed from the standard Kosmos launch announcement by adding that “the scientific research envisaged by the program had been carried out.’’ Within a week US media reports were suggesting the mission had been a test of a small shuttle vehicle, although some argued it had been a test of a prototype spaceborne nuclear weapon targeted on US and British naval forces in the Indian Ocean.

State Commission leader Gherman Titov, who had already pushed for a Black Sea landing on the first mission, now turned to the Military Industrial Commission with a request to have the next BOR-4 land in the Black Sea, expressing his fear the ship could be captured by the Americans. However, he was overruled by his superiors, possibly because Kosmos-1374 had landed well off target and a splash­down in the much smaller Black Sea could not yet be guaranteed. On 15 March 1983, Kosmos-1445 (serial nr. 403) was launched on a repeat mission, coming down 556 km south of the Cocos Islands. On station in the Indian Ocean apart from Navy vessels of the Black Sea fleet were the tracking ships Kosmonavt Vladislav Volkov and Kosmonavt Pavel Belyayev. Two Il-18RT tracking aircraft were in the skies over

Afghanistan to monitor the final part of the re-entry. Coming in the middle of the Soviet-Afghan war, their missions were not without risk and they were protected by a whole squadron of Soviet fighter jets.

Kosmos-1445 was again retrieved by the Yamal. Better prepared than during the Kosmos-1374 mission, the Australian Air Force once again sent out P-3C Orion aircraft to monitor the recovery operation and obtained even better pictures than before, some of which were released to the public by the Australian Ministry of Defense in April 1983. Also keeping a close eye on events were several Australian Navy vessels, which reportedly came so close that the Soviet crew members could use their binoculars to catch a glimpse of the movies shown on giant screens on the upper decks in the evening.

Confident enough now they could bring back the BORs with sufficient precision, the Russians decided to land the next two BORs in the Black Sea just west of Simferopol. The first was launched on 27 December 1983 as Kosmos-1517 (serial nr. 405) and the second was orbited on 19 December 1984 as Kosmos-1614 (serial nr. 406). The TASS launch announcements differed from the earlier ones in acknowl­edging that the satellites “had performed a controlled entry into the atmosphere and

landed in the pre-designated area of the Black Sea.” While Kosmos-1517 was successfully retrieved by the Yamal, it was later revealed that Kosmos-1614 was lost, having either burned up in the atmosphere or sunk in the Black Sea. The recovery vessels, aircraft, and helicopters searched the 70 x 30 km landing ellipse for about a week, but to no avail. Talking about the cause of the mishap many years later, State Commission leader Gherman Titov said that “while fixing one problem, engineers had created another.”

Despite the failure to recover the final vehicle, it was felt that enough data had been gathered during the four orbital flights that a fifth mission was reportedly canceled. The Russians later said the missions had allowed them to test the effects of aerodynamic, temperature, and acoustic loads as well as vibrations on the heat shield between altitudes of 100 and 30 km and speeds of between Mach 25 and Mach 3. Particularly helpful had been the temperature data obtained in critical areas such as the nosecap and the underbelly of the vehicle. The BOR-4 missions had helped to determine the ideal size of gaps between the tiles, measure the “catalytic activity” of the heat shield in real plasma conditions, and also to study the risks associated with losing one or more tiles. The flights had also made it possible to “outline measures to reduce the mass of Buran’s heatshield”, although there is no evidence those measures were actually implemented [17].

“the platform of the cosmonaut emergency evacuation unit—this is where the system which ensures that the rocket’s gyroscopes are installed precisely is situ­ated—did not move away to a safe distance’’ [43].

Reporting on the scrub several days later, Aviation Week interpreted these statements as follows:

“The … launch attempt was scrubbed when the orbiter access arm on the launch pad’s left service structure failed to retract as commanded… The arm extends to the orbiter’s side hatch and allows cosmonauts and technicians to enter the vehicle on the pad. The arm also carries an umbilical connection which provides

ground support to the orbiter’s guidance and navigation system—specifically, its gyroscopes ’’ [44].

The platform in question actually was a 300 kg black plate mounted outside the intertank area of the core stage. It held three instruments needed for pre-launch azimuthal alignment of the core stage’s inertial guidance platforms. The plate, about the size of a small automobile, was installed on the core stage in the Energiya assembly building. After the rocket arrived on the pad, the plate was connected to a swing arm extending from the launch tower. This arm was situated several levels above the orbiter access arm. The retraction process took place in two steps: first, the plate had to disconnect itself from the intertank in three seconds’ time and only after that would the swing arm come into action to safely retract it from the rocket. What happened on 29 October 1988 was that the plate needed forty rather than three seconds to disengage. Sensing the sluggish movement of the plate, the rocket’s on­board computers stopped the countdown and no retraction signal was sent to the swing arm, which obediently remained in place.

Gudilin’s rather confusing statements, which created the impression that an arm had failed to retract from the rocket, led to some discussion at the State Commission the day after the scrub. Particularly unhappy with the confusion was Vladimir Barmin, the chief designer of the launch pad design bureau KBOM, which would have been held responsible if a swing arm problem had really been the culprit. However, the problem was with the plate disconnect mechanism, which was con­sidered the responsibility of the rocket team.

Despite the TASS statement on the 4-hour launch delay, another launch attempt later in the day was never seriously discussed. According to information released much later, the countdown could not be recycled for another attempt the same day if it was halted after the orbiter had switched to internal battery power at T — 80 seconds. Furthermore, by the time the countdown was halted, the umbilicals for thermostatic control of the hydrogen tank had been disconnected and temperatures inside the tank were slowly rising. Therefore, some 10 minutes after the hold was called and the problem had been identified, the team decided to delay the launch for several days and begin the lengthy process of draining the core stage and strap-ons.

Even that did not go entirely by the book. Draining of one strap-on booster’s liquid-oxygen tank went agonizingly slowly, a problem later attributed to a filter that had become clogged by contaminants in the oxidizer tank. Access to the filter at the launch pad was very difficult, causing fears the rocket might have to be rolled back to the assembly building, but in the end the problem was fixed on the pad. One eyewitness later said the clogged filter would probably have caused a catastrophe during launch. If true, the scrub had been a blessing. Also uncovered during post­scrub operations was that an accelerometer in Energiya’s tail section had been inadvertently mounted upside down [45].

The problem with the plate disconnect mechanism had been completely unex­pected. There had been no azimuth orientation system on the Energiya 6SL vehicle launched in May 1987 because there were less stringent requirements for precise orbital insertion of the Polyus payload. Neither had the problem surfaced during

the simulated countdowns at the pad in January-February and May-June. The causes of the mishap were investigated by a team headed by Vyacheslav Filin, a deputy of Gubanov. Part of the troubleshooting was to simulate the forces needed to detach the plate. This was done at the Energiya assembly building using the already assembled Energiya 2L vehicle and also a mock-up core stage intertank structure. In the end, the problem was traced to rubber dust covers on the plate that had somehow become sticky, possibly because of exposure to variable temperatures in the preceding months. In no time, engineers at the Progress plant in Kuybyshev redesigned the dust covers as well as the plate disconnect mechanism to ensure that the problem would not recur [46].

Among the autonomous missions would have been flights with Spacelab-type modules installed in Buran’s cargo bay. NPO Energiya had plans for a so-called “Laboratory Compartment’’ (LO) (index 14F33) that was reportedly based on the 37KB design. This would be connected to the crew compartment by a special tunnel. Such flights would have lasted anywhere from 9 to 30 days and be devoted to scientific, materials-processing, and biotechnological experiments, which take a relatively long time to produce the necessary results. The longest missions would have required the installation of an extra cryo kit for the fuel cells. Buran was also seen as an ideal platform for long-duration unmanned materials-processing and biotechnology missions, benefiting from the undisturbed microgravity environment and the ample power provided by the fuel cells. A military version of the LO known as the Undetachable Useful Payload (NPG) was also considered, but its index 17F32 indicates that it was to be built on the basis of a different design and no further information on it is available [34].