Category Energiya-Buran

Another organization involved in rocket research in the Soviet Union was the Gas Dynamics Laboratory (GDL) in Leningrad. Established in 1921, it was mainly engaged in developing solid-fuel rockets for arming aircraft or assisting aircraft during take-off. In 1929 a small subdivision was added, headed by 20-year-old Valentin P. Glushko, to conduct research on electric and liquid-propellant engines. While the GIRD members were mainly driven by utopian visions of space travel, the GDL team primarily consisted of military-oriented rocketeers and received its modest funding directly from the military.

In 1932 the Red Army Chief of Staff Marshal Mikhail Tukhachevskiy, convinced that the Soviet Union needed modern technology to arm itself against the forces of capitalism, proposed to unite GIRD and GDL into a single institute to develop both solid and liquid-fuel rockets for the military. After many months of negotiations, the new organization, called the Reactive Scientific Research Institute (RNII) was founded in September 1933. Placed in charge of RNII was GDL’s Ivan Kleymyonov, with GIRD’s Sergey Korolyov acting as his deputy.

The different backgrounds of the two organizations soon led to internal conflicts about the future direction of the new institute. Many of these centered around the types of propellants to be used. While the GDL faction favored solid propellants or storable liquid propellants, the former GIRD team promoted engines burning liquid oxygen. Also, Korolyov was hoping to continue work on rocket planes capable of reaching the stratosphere, but this was of little interest to Kleymyonov, who saw the development of military missiles as the institute’s main objective. These and other disagreements caused Korolyov to be demoted to work as a chief engineer in the section for winged missiles in early 1934.

Winged missiles offered several advantages over ballistic missiles in destroying both mobile and stationary targets. Their flight path could be controlled after shut­down of the engines and they could cover much larger distances thanks to the extra lift provided by the wings, thereby compensating for the absence of powerful rocket engines in those days [3]. However, for Korolyov they also provided an opportunity to covertly pursue his dream of achieving manned stratospheric flight.

Ever since the work on the RP-1 rocket plane, Korolyov had become increasingly convinced that it would be difficult to turn existing aircraft or gliders into efficient rocket planes. Neither was the time ripe to put men aboard ballistic missiles. What was needed instead was a new type of winged machine capable of withstanding higher acceleration forces and fitted with low-aspect-ratio wings, a tail section, and a long fuselage to house the propellant tanks. Although the winged missiles tested at RNII in the 1930s were officially seen as precursors to surface-to-air and air-to-surface missiles, Korolyov developed many of them with the goal of manned stratospheric flight in the back of his mind.

At a conference on the use of rockets to explore the stratosphere in March 1935, Korolyov went public with his ideas to build manned winged missiles that could reach altitudes of up to 20-30 km, emphasizing the need to build “flying laboratories” that would pave the way for such vehicles. Apparently, by late 1935 Kleymyonov was impressed enough to include studies of rocket planes in the RNII’s plans for 1936. By early 1936 Korolyov had drawn up a step-by-step plan calling for the development of ever more capable piloted rocket planes. The first of these (218, later renamed 318), powered by either a solid-fuel or liquid-fuel rocket engine, would reach an altitude of 25 km and be flown by two pilots wearing pressure suits. The ultimate goal was to push the ceiling to a phenomenal 53 km [4].

The rocket engines needed for such planes were not yet available, but Korolyov got approval to build an experimental rocket plane based on his SK-9 glider, which he had probably built with that idea in mind. The rocket plane was initially called RP-218-1 and later renamed RP-318-1 after a reorganization within RNII. The engine selected to power the plane was Glushko’s ORM-65, a nitric acid/kerosene engine capable of generating between 50 and 175 kg of thrust and already under development for the 212 winged missile.

The goals formulated by Korolyov for the rocket plane program in early 1936 were “to achieve a record altitude and speed’’ and “to obtain the first practical experience in solving the problem of piloted rocket flight’’ [5]. To him personally, it was probably the first step on the long road to manned space travel, but Korolyov

was well aware that this would not be enough to receive continued support for the program. As he would have to do more than once in his later rocket and space career, he had to justify his efforts by coming up with military applications. In a study requested by Korolyov, the Zhukovskiy Air Force Academy concluded in 1937 that, despite the limited operating time of the rocket engine, rocket planes could play a vital role as fighters [6]. Their main task would be to intercept enemy bombers. With the development of jet engines in an embryonic stage, rocket engines would be the only practical way of significantly increasing speed in the near future.

After an exhaustive series of tests, the ORM-65 was installed in the SK-9 in September 1937 and began a series of integrated test firings in December 1937. Korolyov was intent on piloting the RP-318-1 himself, going down in history as the first man to fly a rocket plane. However, by this time Stalin’s purges were beginning to sweep through the ranks of RNII (renamed NII-3 in 1937). Tukhachevskiy, Kleymyonov, and his deputy Langemak were executed in January 1938, and Glushko and Korolyov were arrested on trumped-up charges in March and June 1938, disappearing into the Soviet prison system for the following six years.

Work on the RP-318-1 was not resumed until the end of the year under the leadership of A. Shcherbakov. The ORM-65 was replaced by a somewhat simplified but more reliable version called the RDA-1-150 with a thrust of between 50 and 146 kg, developed by Glushko’s successor Leonid Dushkin. After being installed in the plane, it underwent a series of more than 100 test firings between February and October 1939.

In November 1939 the RP-318-1 was transported to an aerodrome in the out­skirts of Moscow, where after several more test firings of the rocket engine it made its first historic flight on 28 February 1940. Piloted by Vladimir Fyodorov, the 675 kg and 7.9 m long rocket plane was towed into the air by an R-5 airplane and released at an altitude of 2.8 km. After gliding down to an altitude of 2.6 km, Fyodorov ignited

the RDA-1-150 engine, which burned for 110 seconds, accelerating the plane from 80 to 140 km/h and taking it to an altitude of 2.9 km. There were two more flights on 10 and 19 March 1940. If it hadn’t been for the delays caused by the repression in the late 1930s, the RP-318-1 might very well have become the world’s first aircraft propelled by a liquid-fuel rocket engine. In the event that distinction went to the German Heinkel He-176, which made its maiden flight on 20 June 1939 using a rocket engine fueled by hydrogen peroxide.

With the threat of a German invasion looming, there was increasing interest in the use of rocket-propelled aircraft to improve combat efficiency. On the one hand, dedicated rocket-propelled fighters could use such engines to quickly intercept enemy bombers as soon as they appeared over the horizon and then immediately glide back to the runway, completing their mission in a matter of minutes. On the other hand, rocket engines could also be installed on existing aircraft in addition to the traditional piston engines to either assist in take-off or abruptly increase speed during flight to overtake or evade enemy aircraft. Any utopian visions of space travel quickly faded into the background. However, the World War II rocket planes provided further experience in the field of piloted rocket flight and gave the Soviets an opportunity to continue work on rocket engines, no matter how modest their performance was in comparison with the powerful rocket engines concurrently under development in Germany for the A-4 (“V-2”) missile.

The only Soviet short-range interceptor that ever made powered flights during the war was the BI (for blizhniy istrebitel or “short-range fighter’’), developed at the OKB-293 design bureau of Viktor Bolkhovitinov under the leadership of Aleksandr Bereznyak and Aleksey Isayev. It had a fabric-skinned wooden frame, low-mounted straight wings, a “razorback’’ style canopy and twin 20mm cannons mounted in front of the canopy. Installed in the aft was a D-1A-1100 nitric acid/kerosene engine developed by Dushkin at NII-3 capable of throttling between 400 kg and 1,100 kg. The originally planned turbopump was replaced by a pressure-fed system designed by Isayev. With a maximum propellant load of 705 kg, the engine could burn for almost two minutes. Maximum take-off mass was 1,650 kg (dry mass 805 kg).

Work on the BI began in late 1940, but was not given priority until after the German invasion of the Soviet Union in June 1941. In July Stalin ordered the OKB-293 team to build the first BI in just 35 days instead of the three to four months that Bereznyak and Isayev had planned. Amazingly, the first BI was duly delivered in mid-September and in the following weeks made 15 unpowered flights, towed by a Pe-2 bomber. In October 1941, with German troops approaching Moscow, Bolkhovitinov’s design bureau was evacuated to the Urals near Sverdlovsk, where the BI-1 tests continued with a series of static test firings and take-off runs. The first

powered flight took place on 15 May 1942 with Grigoriy Bakhchivandzhi behind the controls. The D-1A-1100 boosted the BI-1 to an altitude of 840 m and a maximum speed of 400 km/h. Just over three minutes after take-off, the BI-1 made a hard landing, seriously damaging its landing gear.

The next test flights were performed with the BI-2 and BI-3, which only differed from the first aircraft in having a skid landing gear. The BI-2 made four flights in January-March 1943 (three by Bakhchivandzhi and one by Konstantin Gruzdev), pushing the maximum speed and altitude to 675 km/h and 4 km, respectively. Bakhchivandzhi was again at the helm for flights 6 and 7 on the BI-3. Unfortunately, the seventh flight on 27 March 1943 ended in tragedy, when the BI-3 went into a dive shortly after engine shutdown and crashed, killing its pilot. The accident had a stifling effect on the rocket plane program, the more so because the cause was never clearly established. Plans for building a batch of 50 production planes (BI-VS) equipped with small bombs were canceled. However, more experimental planes were built with the goal of increasing the very limited flight duration, which was seen as one of the main disadvantages of the plane. One BI version was fitted with two wing-mounted ramjet engines and another one with an improved 1,100 kg thrust engine developed by Isayev (the RD-1). Both made test flights in 1944 and 1945.

NII-3, now headed by Andrey Kostikov, did not only provide the engine for the BI, but also worked on its own short-range interceptor. Originally, the institute had hoped to build upon the success of the RP-381-1 by equipping the plane with an improved 300 kg thrust RD-1-300 engine that would have allowed it to take off on its own power. Also studied was a rocket plane based on the G-14 glider with a liquid oxygen/ethanol RDK-1-150 engine developed by Dushkin. However, in 1940 those plans were abandoned in favor of a short-range interceptor called “302”, which would have a liquid-fuel rocket engine mounted in the rear fuselage and two ramjets under the wings to increase flight duration, giving it an advantage over the BI. The rocket engine was Dushkin’s RD-1400 (later renamed RD-2M), capable of throttling between 1,100 and 1,400 kg.

Work was temporarily suspended after the German invasion in June 1941, when NII-3 concentrated all its efforts on the famous Katyusha missiles. However, in 1942 Stalin ordered work to be resumed, with aircraft designer Matus Bisnovat joining the team in early 1943. A glider version called 302P was flown several times in late 1943 (towed by Tu-2 and B-25 aircraft) and was piloted among others by the later cosmonaut candidate Sergey Anokhin. Unfortunately, development problems with both the rocket and ramjet engines, the availability of the BI fighters, and the decreasing interest in rocket-propelled interceptors eventually led to the cancellation of the project in early 1944. Kostikov, who had reportedly denounced both Glushko and Korolyov in 1938, was now arrested himself for having made unauthorized changes to the test program, but was rehabilitated in February 1945.

There were also several interceptor proposals that never went beyond the drawing board. In 1942 the Yakovlev design bureau finished the design of a rocket plane based on its YaK-7 aircraft. Called the YaK-7R, it would carry a single Dushkin D-1-A-1100 rocket engine in the tail and two Merkulov DM-4S ramjets under the wings. However, the project stalled due to development problems with the ramjets. In late 1943 the OKB-51 design bureau of Nikolay Polikarpov began work on a rocket plane called Malyutka (“Baby”) using an unidentified rocket engine with a thrust of between 1,000 and 1,200 kg. Malyutka was expected to develop a speed of 845 km/h and reach a maximum altitude of 16 km during an 8 to 14 minute flight. The project was canceled after Polikarpov’s death in July 1944.

Other proposals were based on the use of a 1,200 kg thrust, four-chamber nitric acid/kerosene engine designed by Valentin Glushko. Equipped with a turbopump, it was called RD-1, not to be confused with its namesake developed by Isayev for the BI. Still a prisoner, Glushko was working at the time for the 28th Special Department of the NKVD secret police in the city of Kazan. This was a so-called sharaga, a type of penitentiary for scientists and engineers to work on projects assigned by the Communist Party.

One man displaying interest in the engine was Roberto Bartini, an Italian-born aircraft designer who as a member of the Italian Communist Party was transferred undercover to the USSR in 1923 after the Fascist revolution. Arrested in 1937 because of his ties to Tukhachevskiy, Bartini ended up in the 29th Central Design Bureau (TsKB-29) of the NKVD in Omsk, a sharaga that served as the engineering facility for Andrey Tupolev. During 1941-1942 he drew up plans for a rocket plane with swept-back wings called R-114 that would use the RD-1 to reach phenomenal speeds of over 2,000 km/h.

Glushko’s RD-1 also figured prominently in rocket plane proposals by Sergey Korolyov, who, after having barely survived the hardships of the Kolyma gulag camps in far eastern Siberia, had been sent back west in 1940 to work under Tupolev at TsKB-29 (first in Moscow, then in Omsk) and was subsequently transferred to Glushko’s sharaga in Kazan in November 1942. The following month he finished plans for two rocket planes, one weighing 2,150 kg and the other 2,500 kg, with Korolyov preferring the latter version. Equipped with the four-chamber RD-1, the plane would be able to intercept any enemy aircraft at any altitude and even be capable of attacking ground-based targets such as tanks, artillery batteries, and surface-to-air missile installations. It would outperform the BI in every respect, staying in the air for 10.5 minutes (vs. 2 minutes for the BI) at a speed of 800 km/ h and carrying 200 kg of weaponry (vs. 50-100 kg for the BI-1). Korolyov also suggested mounting an RD-1 type engine on a 3,500 kg “flying wing” type interceptor that would be able to stay in the air for 30 minutes and reach a maximum altitude of 15 km. A similar flying wing (“RM-1”) with a Dushkin RD-2M-3V engine was studied by the OKB-31 design bureau of Aleksandr Moskalyov in 1945-1946.

Advanced as both Bartini’s and Korolyov’s proposals may have been, they had little resonance. Put forward by men who officially were still “enemies of the people’’, they stood little chance against official, government-supported projects such as the BI and “302” [7].

Another application of liquid-fuel rocket engines in aviation was to augment the performance of existing aircraft. In 1932 GDL had worked on a project to install two ORM-52 engines on the I-4 (ANT-5) fighter to improve its combat performance, but those plans were never realized due to the institute’s high workload. In 1939-1940 Glushko proposed to use the ORM-65 engines on experimental bombers called S-100 and Stal-7, but he was eventually ordered to develop the four-chamber RD-1. By the time Korolyov arrived in Kazan in late 1942, a 300 kg thrust single-chamber version of the engine was already undergoing tests.

Korolyov proposed to fly this version of the engine on a Pe-2 dive-bomber of aircraft designer Vladimir Petlyakov, not only to augment its performance, but also to speed up the development of the four-chamber version that Korolyov intended to employ on his short-range interceptor. With the engine installed in the rear fuselage of the plane, the RD-1’s turbopump would be driven by one of the two M-105 propeller engines mounted under the wings. The combination of the RD-1, the fuel tanks, the turbopump assembly, propellant feed systems, and other components was known as RU-1.

The first rocket-powered flight of the modified Pe-2 bomber (Pe-2RD) took place on 1 October 1943. The first two series of test flights, with the engine either ignited during take-off or at altitudes less than 5 km, revealed problems with the RD-1’s electric ignition system, which was therefore replaced by a chemical ignition system. The modified engine (RD-1KhZ) was subsequently flown in a third series of test flights and was ignited at altitudes up to 7 km. In 1943-1945 the Pe-2RD made more than 100 flights. Korolyov was on board for some of the test flights. Plans for further modifications of the rocket-powered Pe-2 were never realized.

The RD-1 and RD-1KhZ were also flown on three Lavochkin planes (La-7R1, La-7R2, and La-120R) in 1944-1946, on the Sukhoy Su-7 in 1945, and on the Yakovlev YaK-3 in 1945. However, partly because of the low reliability of the

RD-1 engine and also because of the emergence of the jet engine, none of these planes ever went into production [8].

With turbojet development in the Soviet Union slow to take off, there was continued interest in rocket-propelled aircraft in the first post-war years, not only to counter the new threat of US strategic bombers, but also to explore the behavior of aircraft at supersonic speeds.

One project was initiated before the end of the war at NII-1, the new name given to the former NII-3 after it had merged in May 1944 with Bolkhovitinov’s OKB-293 (which also included a rocket engine department headed by Isayev). Headed by Ilya Frolov, the new effort was mainly intended to compare the performance of a pressure-fed and a turbopump-fed engine in future rocket fighters. For this purpose NII-1 developed two aerodynamically identical airplanes with straight wings: 4302 nr. 2 with a pressure-fed Isayev RD-1M engine and 4302 nr. 3 with a turbopump-fed Dushkin RD-2M-3. The RD-2M-3 was a two-chamber design with a 1,100 kg thrust main chamber and a 300 kg thrust supplementary chamber. Both chambers would be used for take-off, after which the pilot would shut down the main chamber and use the thrust of the smaller one to search for and engage the target. This technique was more fuel-efficient and allowed the plane to stay in the air longer. A glider version (4302 nr. 1) towed by a Tupolev Tu-2 made 46 flights beginning in 1946. Of the two rocket-powered versions only 4302 nr. 2 was eventually flown, making one single flight in August 1947 before funds were transferred to another rocket plane project initiated by Mikoyan.

In February 1946 the Soviet government ordered both the OKB-301 Lavochkin bureau and the OKB-155 Mikoyan bureau to develop rocket interceptors capable of reaching speeds up to Mach 0.95 and altitudes of up to 18 km. Both planes were to be equipped with modified Dushkin RD-2M-3V dual-chamber engines. Lavochkin’s team studied a plane with a radar sight called La-162, but abandoned work on it in late 1946, preferring to fully concentrate their efforts on jet aircraft. The Mikoyan version was called I-270 and was heavily influenced by the German Me-263-V1 rocket fighter, which had been captured by the Red Army and carted off to the Soviet Union. The Me-263-V1 was one in a long line of Messerschmitt rocket fighters, one of which (the “Komet”) had been the only rocket fighter ever to be used in combat. Although the I-270 featured a similar cockpit and landing gear arrangement, it was substantially longer than the Me-263 and also had mid-mounted straight wings and a tee tail rather than the swept wings and tailless design of the German interceptor.

Two experimental I-270 planes were built, one designated Zh-1 and the other Zh-2. Towed by a Tu-2 bomber, Zh-1 made 11 unpowered test flights between February and June 1947. Zh-2 performed the first rocket-propelled flight in Septem­ber 1947, but was irreparably damaged when it landed far off the runway. Zh-1 also suffered damage on its first powered flight in October 1947 when the landing gear

failed to deploy, but was repaired for one final flight in May 1948. The test flights were rather conservative, with the planes developing speeds of only about 600 km/h.

In the second half of 1945 the design bureau of Pavel V. Tsybin was tasked with studying various wing configurations for use at near supersonic speeds. For this purpose the bureau developed “Flying Laboratories” (LL) powered by a Kartukhov PRD-1500 solid rocket motor. Two configurations were tested: LL-1 (or Ts-1) with straight wings and LL-3 (or Ts-3) with 30° forward-swept wings. The LL-1 and LL-3 made about 130 flights in 1947-1948, with the latter reaching speeds of up to Mach 0.97. A planned LL-2 with 30° swept-back wings was not flown because that wing configuration had already been tested on the MiG-15 and La-15 fighters.

Meanwhile, the Soviets were also out to break the sound barrier with rocket – propelled airplanes, relying both on a captured German and a derived domestic design. The German rocket plane was the 346, originally developed by the German Institute for Sailplane Flight (DFS) in 1944. After shutting down its engine, the plane was supposed to glide over enemy territory to take reconnaissance photos and then re-ignite the engine to gain enough speed and altitude to glide back to a friendly base in France or Germany. It had a long, slender fuselage reminiscent of a rocket, with 45° swept-back wings. Thrust was to be provided by a dual-chamber HWK 109-509C. The pilot was supposed to lie in a prone position. In case of an emergency the cabin could be separated from the airplane, with the pilot subsequently ejecting for a parachute landing.

Having fallen into Soviet hands at the end of the war, the German team that had been working on the 346 was sent to Podberyozye (some 100 km north of Moscow) in October 1946 to continue development of the rocket plane under the leadership of Hans Rossing in a newly created Soviet-German design bureau called OKB-2. In the second half of 1948 Rossing’s team completed work on a glider version of the plane called 346-P, which was flown several times by German test pilot Wolfgang Ziese in 1948-1949. The carrier aircraft for these and subsequent test flights was an American B-29 bomber confiscated by the Russians after having made an emergency landing in Vladivostok in 1944. In 1949 Ziese and Soviet pilot Pyotr Kazmin were behind the controls for three drop tests of a version of the 346 carrying a mock-up rocket engine (346-1). Despite landing problems on all three flights, the team pressed ahead with the development of the first rocket-propelled model called 346-3.

Ziese performed three powered flights in August-September 1951. During the third flight he lost control of the plane after engine shutdown, forcing him to separate the cabin and eject. With only one of the two combustion chambers activated during these test flights, the maximum speed reached was just over 900 km/h. The 346 could have broken the sound barrier with both chambers working, but OKB-2 was reportedly wary of making such an attempt because of aerodynamic in­sufficiencies in the airplane. Plans for a delta-wing supersonic rocket plane called 486 were scrapped and the German team was eventually repatriated to the GDR in 1953.

Concurrently with the Germans at Podberyozye, a team under Matus Bisnovat worked on an indigenous supersonic rocket plane called Samolyot-5 (“Airplane-5”). Bisnovat had been placed in charge of the OKB-293 design bureau in June 1946,

when it separated from NII-1 to once again become an independent entity. With its 45° swept-back wings, Samolyot 5 was outwardly very similar to the 346, also featuring a jettisonable cabin. It would use a twin-chamber Dushkin RD-2M-3F with a total thrust of 1,600 kg to reach speeds of up to Mach 1.1.

Bisnovat’s team initially developed a scale model called “Model 6” that was dropped on four occasions from a Tu-2 bomber between September and November 1947. Claims that speeds of Mach 1.28 and Mach 1.11 were attained on the two final flights are hard to verify because the speedometers were not retrieved intact. With the Dushkin engine not yet ready, a glider version designated 5-1 performed three drop tests from a Pe-8 bomber between July and September 1948, but it was damaged beyond repair in a landing accident on the final mission. Eight or nine more drop tests were conducted with airplane 5-2 between January and June 1949, but that same year financing for Samolyot-5 was discontinued even though the Dushkin engine had been test-fired and installed on the 5-2 [9].

By the end of the 1940s the era of the rocket planes was drawing to a close. Because of their limited flight times, they had little military value, among other things because the pilot had a hard time gliding back to a safe landing. Another safety issue was the use of toxic nitric acid in all the rocket engines developed for the Soviet rocket planes. A much cheaper, safer, and more efficient way of shooting down enemy bombers was the use of surface-to-air missiles, something that the Russians realized shortly after the end of the war when they stumbled on advanced German SAM missiles such as the Wasserfall.

After the war, rocket engines were a handy way of testing aircraft performance at supersonic speeds, but their development was gradually being overtaken by that of the jet engine, even though the Russians mainly relied on copies of German and British engines. While Chuck Yeager had become the first man to break the sound barrier on the X-1 rocket plane on 14 October 1947, the Russians achieved the same feat a year later, but not on one of their rocket-propelled aircraft. On 26 December 1948 Oleg Sokolovskiy became the first Soviet pilot to exceed Mach 1, flying a

Lavochkin La-176 jet plane. Despite the simultaneous development of the 346 and Samolyot-5, no Russian pilot ever flew faster than the speed of sound on a rocket – propelled aircraft. In the first half of 1950 a special commission set up under the Ministry of the Aviation Industry concluded that rocket engines had little future in aviation and a government decree in June 1950 closed down all further work on rocket engines for aircraft at NII-1.

Ever since the reorganization of NII-1 under the Ministry of the Aviation Industry in 1944, one of its main goals had been to incorporate rocket and ramjet technology into aviation. On 29 November 1946 the new head of NII-1 became Mstislav Keldysh. One of his first assignments was to study a German hypersonic winged trans­continental bombardment aircraft known as the Silbervogel (“Silver Bird”) or the “antipodal bomber”. This was the brainchild of Dr. Eugene Sanger and mathematician-cum-wife Irene Brendt, who proposed it in a document in August 1944, one copy of which was found by the Russians in Germany after the war. Launched horizontally by a rocket-powered sled, it would use its own rocket engines to boost itself to orbital altitude and subsequently ricochet off the Earth’s atmo­sphere, dropping a bomb over the desired target during one of the dips. Stalin was impressed enough by the Silbervogel to dispatch an Air Force officer named Grigoriy Tokaty-Tokayev to kidnap Sanger in France in 1948, but Tokaty-Tokayev took the opportunity to defect to the West instead [10].

Actually, by this time Keldysh had already come to the conclusion that the Silbervogel was an unrealistic design, among other things because of the high specific impulse required for the engines and the high propellant load. In 1947 he had come up with an alternative intercontinental bomber that would use a combination of supersonic ramjets (scramjets) and rocket engines to perform a mission very similar

to the Silbervogel. In what amounted to the first serious Soviet spaceplane proposal, Keldysh’s single-seater bomber would be horizontally rail-launched as the Sanger/ Bredt bomber, but then switch to two wing-mounted scramjets to reach an altitude of 20 km. Subsequently, the scramjets would be jettisoned, after which a 100-ton thrust rocket engine would kick in to send the vehicle to the upper reaches of the atmosphere, where it would fly several “dip-and-skip” trajectories to reach its final target. The scramjet and rocket engines would share several systems such as a common kerosene tank and also a common hydrogen peroxide tank to drive the turbopumps [11].

As the Cold War shifted into higher gear in the late 1940s, the Russians began looking at more realistic ways of delivering nuclear warheads over intercontinental distances. Unlike the US, the USSR did not have the luxury of having bases along the enemy borderline, making rockets a more convenient way of transporting nuclear bombs than strategic bombers. The leading rocket research institute was NII-88, set up in 1946. Sergey Korolyov, released from the sharaga in 1945 to study V-2 missiles in Germany, headed one of its departments. By the end of the decade NII-88 was investigating both ballistic and cruise missiles as a means of delivering nuclear bombs over long distances. In the winged arena, the emphasis now shifted from a hori­zontally launched piloted bomber with rocket and scramjet engines to a vertically launched unmanned two-stage cruise missile carrying rocket engines in the first stage and supersonic ramjets in a winged second stage. Unlike the ballistic missiles, the cruise missiles would remain within the boundaries of the Earth’s atmosphere, developing top speeds of around Mach 3.

A Soviet government decree issued on 4 December 1950 approved a new rocket research program, one part of which (“theme N-3’’) focused on intercontinental missiles. The conclusion of the N-3 studies was that the development of a cruise missile with a range of 8,000 km was feasible, but needed to be preceded by further

research into scramjets and navigation systems. A government decree on 13 February 1953 gave the go-ahead for the simultaneous development of both intercontinental ballistic and cruise missiles, assigning both tasks to OKB-1, which was the name given to Korolyov’s reorganized department within N11-88 in 1950. Since the cruise missile required a significant leap in technology, OKB-1 would first design an intermediate Experimental Cruise Missile (EKR). With a targeted range of 730 km, it would consist of an R-11 missile as the first stage and a winged second stage with a Bondaryuk RD-40 scramjet.

By the end of 1953 preliminary ground-based testing of EKR components had given the Russians enough confidence to skip this intermediate step and move directly to an intercontinental cruise missile with a range of 8,000 km. Since Korolyov’s OKB-1 was too heavily preoccupied with its R-7 ICBM, responsibility for the cruise missiles was entrusted to the aviation industry by a government decree released on 20 May 1954. Three aviation design bureaus were tapped to build cruise missiles with different missions:

• OKB-49 (Georgiy Beriyev): a missile called Burevestnik (“Petrel”) or “P-100” to be used for long-range reconnaissance (fulfilling the same role as the American U-2 reconnaissance aircraft) and also to deliver small 1.2-ton nuclear warheads.

• OKB-301 (Semyon Lavochkin): a missile called Burya (“Storm”) or La-350 to transport 2.18-ton atomic bombs.

• OKB-23 (Vladimir Myasishchev): a missile called Buran (“Blizzard”) or M-40 to transport 3.4-ton hydrogen bombs.

Keldysh’s NII-1, which had once again become independent in 1952 after having been a branch of the Central Institute for Aviation Materials (TsIAM) since 1948, had overall scientific supervision of the cruise missile effort, relying on its earlier experience in high-speed and high-altitude aeronautics obtained during the antipodal bomber projects.

All cruise missiles consisted of a “core stage’’ with air-breathing scramjet engines, flanked by rocket-powered “strap-on boosters’’ (two for Burevestnik and Burya and four for Buran), giving them an appearance somewhat reminiscent of the Space Shuttle. Burevestnik seems to have been a very short-lived program that never came close to flying. Buran featured four first-stage boosters with Glushko RD-212 kerosene/nitric acid engines and a core stage with a Bondaryuk RD-018 scramjet. In August 1956 OKB-301 started work on an improved version (Buran-A or M-40A) with upgraded RD-213 engines, increasing payload capacity to 5 tons. Interestingly, Myasishchev at one point considered equipping Buran with a small crew cabin, from which the pilot was to eject prior to impact. One of the objectives of this plan was to see if a man could endure the psychological and physical rigors of hypersonic flight. Buran was scrapped in November 1957 before making its first flight.

Burya’s two strap-ons had Isayev S2.1100 rocket engines (later replaced by the S2.1150) and the core stage was powered by a Bondaryuk RD-012 scramjet. The missile underwent a series of 17 test flights from the Vladimirovka test range in the Volgograd region between September 1957 and December 1960. The maximum range achieved was 6,425 km, less than the prescribed 8,000 km, because the scramjet had a tendency of igniting too early. However, even as Burya was overcoming its teething problems, its fate had already been sealed by the successful test flights of OKB-1’s R-7 ICBM, the first of which took place in August 1957. Cruise missiles were very vulnerable to defensive measures due to their low flight altitudes (around 17-25 km) and took more than two hours to reach their targets, whereas ICBMs could deliver their deadly cargo in a matter of minutes. The US Air Force had come to the same conclusion, closing down its Navaho intercontinental cruise missile project in July 1957. The Soviet government followed suit by releasing a decree on 5 February 1960 that canceled all further work on Burya, although it allowed some of the remaining missiles to be tested in flight [12].

For many years official histories of the Soviet space program created the impression that Vostok had been the only Soviet piloted space project in the late 1950s/early 1960s. Not until the days of glasnost in the late 1980s/early 1990s did it emerge that just like the United States the Soviet Union had considered winged spacecraft as an alternative to ballistic capsules in the early years of the space program. Surprisingly, it turned out that this option was studied in no fewer than five design bureaus.

In the US winged spacecraft were long seen as the logical culmination of research into high-speed aeronautics conducted since the mid-1940s with air-launched rocket – propelled X-planes. The first phase had seen aircraft such as the X-1, X-2, and

Skyrocket gradually push the envelope from Mach 1 to Mach 3 between 1947 and 1956. Phase 2 had been initiated in late 1954 with the decision to press ahead with the development of the X-15 high-altitude hypersonic research aircraft, which eventually performed a largely successful test program between 1958 and 1969. Ultimately, suborbital and orbital capability would be achieved using the “boost-glide” principle, where a spaceplane would be launched vertically with the help of a con­ventional rocket and eventually glide back down to the runway like an ordinary aircraft. In late 1957, responding to Sputnik, the Air Force consolidated three “boost-glide” feasibility studies (Hywards, Brass Bell, and Rocket Bomber) into a single program called “Dyna-Soar” or X-20. Unlike the X-15, however, Dyna-Soar was not seen as an experimental system, but an operational weapon system capable of orbital nuclear bombardment, reconnaissance, and satellite identification and neutralization [13].

During 1958 the exigencies of the Cold War and the fledgling space race with the Soviet Union gradually pushed the ballistic capsule approach to the foreground, especially after the formation of NASA in October of that year. Having lost face after the early Sputnik successes, the United States was intent on restoring its reputation by putting the first man into orbit and capsules were a more efficient and quicker way of achieving that goal than winged spacecraft. The Air Force continued work on Dyna-Soar against the backdrop of NASA’s Project Mercury, but in December 1963, with the first flight an estimated three years away, Secretary of Defense Robert McNamara canceled the program. X-20 funds were reappropriated to a military space station called the Manned Orbiting Laboratory (MOL). After that the United States did not have another officially sanctioned spaceplane project until the approval of the Space Shuttle by President Nixon in early 1972.

The winged approach to piloted spaceflight was probably less central in Soviet thinking than it was in the US, at least when it came to building the first manned spacecraft. For one, the Soviet aviation industry and the Air Force were far removed from missiles and space-related matters after the Ministry of the Aviation Industry had declined offers in 1945-1946 to bear responsibility for long-range missile pro­grams. Instead, the assignment went to the Ministry of Armaments, which had developed artillery during the Second World War. This had far-reaching implications for the Soviet space program (essentially an offshoot of the missile program), which until the break-up of the USSR remained tightly in the grip of the “artillery” camp. Moreover, missiles were soon favored over strategic bombers to deliver nuclear warheads to US territory and there was little incentive for research into high-speed, high-altitude aircraft, reflected in the absence of high-altitude “X-type” airplane research programs in the Soviet Union. On top of that, Soviet leader Nikita Khrushchov had become particularly enamored with missiles in the mid-1950s, curtailing contracts for the aviation industry and even dissolving several aviation design bureaus towards the end of the decade.

The earliest plans for piloted missions beyond the atmosphere revolved around the use of converted R-2 missiles to send people on vertical trajectories to altitudes of up to 200 km. Although one common cabin design was planned, different methods were studied for returning the capsule to Earth. One option presented by Korolyov

during a speech in September 1955 was to equip such a capsule with wings, allowing it to make a long ballistic suborbital flight rather than a short vertical hop [14].

Research on piloted spaceflight began in earnest in the spring of 1957 with the establishment within OKB-1 of Department 9, which was to focus exclusively on the development of lunar probes and piloted spaceships, signaling the beginning of the bureau’s reorientation from missiles to spaceflight. Between September 1957 and January 1958 OKB-1 and the NII-1 research institute carried out a comparative analysis of various basic shapes for piloted spaceships, paying particular attention to thermal protection requirements and the ^-forces exerted on the crew. The con­clusion was that the heat-resistant alloys available at the time were not up to the task of protecting winged vehicles with high lift-to-drag ratios against the severe thermal stresses of re-entry. Instead, the recommendation was that the first piloted spaceship should have a lift-to-drag ratio between just 0.5 and 0, depending on the ^-forces that were deemed acceptable for the crew. The ship would preferably be shaped as a blunt cone with a rounded nose and a spherical base, with the pilot being ejected from the descent capsule before touchdown.

In April 1958 one of the main obstacles to manned ballistic flight was eliminated when a key meeting of leading experts in the field of aviation medicine came to the conclusion that people could withstand forces of up to 10g as long as the body was properly positioned inside the capsule. All this would lead later that year to preliminary designs for the manned vehicle that eventually became Vostok, redesigned in early 1959 to serve the dual function of carrying people into space and performing unmanned photoreconnaissance missions [15].

Nevertheless, Korolyov, a veteran of several rocket plane projects in the 1930s and 1940s, did not abandon the idea of winged piloted spaceflight. Outlining their ideas on the future of spaceflight in a joint letter to the government on 5 July 1958, Korolyov and his associate Mikhail Tikhonravov called for developing a manned space capsule in the 1958-1960 timeframe and then to design a manned vehicle “with a gliding return profile” in 1959-1965 [16].

Preoccupied with work on the R-7 rocket and the first satellites, Korolyov turned to a befriended aircraft designer to start preliminary research on a manned space – plane. This was Pavel V. Tsybin, who had got acquainted with Korolyov back in the early 1930s while building gliders. After leading research on the LL “flying labora­tories” in the late 1940s, Tsybin worked on missiles at N11-88 from 1949 to 1951 and subsequently became involved in the design of the air-launched Kometa anti-ship cruise missile at the Mikoyan design bureau. Finally, in May 1955 Tsybin was placed in charge of a newly founded design bureau called OKB-256, situated in Podberyozye, which in 1956 became part of the newly founded city of Dubna. Its primary assignment was to create the RS, a long-range bomber powered by super­sonic ramjet engines, although by mid-1956 the focus had shifted to a supersonic reconnaissance aircraft named RSR.

Sometime later, presumably in 1958, Korolyov proposed Tsybin to design a small winged spaceship that could be orbited by an R-7 based rocket. Tsybin’s team readily set to work, assisted by specialists from OKB-1. What they came up with was a vehicle called PKA (for “Gliding Space Apparatus’’), which because of its shape was also nicknamed Lapotok (“little bast shoe’’).

Having a launch mass of 3.5 tons, the one-man spaceplane was to be placed into a circular 300 km orbit by a Vostok rocket for missions lasting up to 24-27 hours. Built into the fuselage was a small pressurized cabin with a control panel, life support systems, and three windows, one of them for an astronavigation system. In case of a launch abort, the pilot could eject from the cabin up to an altitude of 10 km and in an emergency at higher altitudes the entire spaceplane would be separated from the rocket. Located behind the cabin was a pressurized instrument compartment with on-

orbit and re-entry support systems. The spaceplane also had a detachable engine compartment with two 2,350 kg thrust nitric acid/kerosene engines, one for on-orbit maneuvers and the other for the deorbit burn. Also on this compartment were an infrared vertical sensor and a thermal control system using radiators. The dry mass of the engine unit was 350 kg and the propellant mass at launch was 430 kg. For orientation in orbit and during the early stages of re-entry the ship used small hydrogen peroxide thrusters.

The deorbit, re-entry, and landing phase was to last up to 90 minutes. After the deorbit burn the engine compartment was to be separated at an altitude of 90 km. During re-entry the spaceplane’s steel fuselage was protected from the high tempera­tures by a heat shield consisting of a 100 mm thick organic silicon layer and a 70 mm thick fibre layer as well as by special air ducts to cool the outside structure. Places with maximum heat exposure such as the nose of the heat shield and the leading edges of the two elevons and the tail were to be cooled with the help of liquid lithium. During maximum heating the angle of attack was 55 to 60°. At an altitude of 20 km, having reduced its speed to 500-600 m/s, the PKA would deploy two wings with a span of 7.5 m and an area of 8.7 m2, which until then had remained folded back to protect them against the highest temperatures during re-entry. The spaceplane was to land on a dirt runway using a skid landing gear. Landing speed was 180-200 km/h and landing mass was 2.6 tons.

The preliminary design (“draft plan’’ in Russian terminology) for the PKA was officially approved by Tsybin on 17 May 1959 and the following day Korolyov sent a letter to the State Committee of Defense Technology (GKOT, the former Ministry of Armaments) with the request to include the spaceplane in its long-range plans and assign OKB-256 to the project as the lead organization [17]. However, wind tunnel tests conducted at the Central Aerohydrodynamics Institute (TsAGI) showed that the PKA would be exposed to much higher temperatures than expected (up to 1,500°C), requiring significant changes to the heat shield. Moreover, it turned out

that the use of liquid lithium to cool the hottest parts of the fuselage would make the design much heavier and more complex than anticipated [18].

Tsybin invited specialists of the All-Union Institute of Aviation Materials (VIAM) to deal with these issues, but by the end of 1959 clouds were gathering not only over the PKA, but over Tsybin’s design bureau as well. The RS supersonic strategic bomber had been canceled in the wake of the Soviet Union’s early ICBM successes and in October 1959 OKB-256 was absorbed by Myasishchev’s OKB-23. When OKB-23 in turn became a branch of Vladimir Chelomey’s OKB-52 in late I960, Tsybin returned to Korolyov’s OKB-1, where he would eventually go on to play an important role in the Energiya-Buran program and later in the design of single-stage-to-orbit spaceplanes [19].