Category Energiya-Buran

The roots of Buran

When Buran swooped down to a safe landing on its Baykonur runway on 15 Novem­ber 1988, it marked the culmination of more than just the 12 years needed to take it to the launch pad since its official approval by a Soviet government and Communist Party decree in February 1976. Even by the start of the Buran program the Soviet Union possessed a rich database on high-speed aeronautics, gradually accumulated through four decades of work on rocket-propelled aircraft, intercontinental cruise missiles and smaller spaceplanes.

THE FATHER OF SOVIET SPACEPLANES

The first man in the Soviet Union to widely advocate the idea of winged spacecraft was Fridrikh Tsander. Born in 1887 in the Latvian capital Riga into an intellectual German family, Tsander became obsessed with the idea of space travel around the age of 20 and was one of the Soviet Union’s most prominent popularizers of space exploration in the 1920s (with one of his lectures attended by Lenin himself in December 1920). Although inspired by the work of great spaceflight theoreticians like his compatriot Konstantin E. Tsiolkovskiy and the German Hermann Oberth, Tsander was convinced that the most practical way of reaching other planets was not with powerful and expensive rockets, but with winged vehicles. Tsander outlined his ideas in the journal Tekhnika і zhizn in 1924 in an article called “Flights to Other Planets’’, openly taking issue with the ideas of Oberth and Tsiolkovskiy:

“For flight to the upper layers of the atmosphere and also for landing on planets possessing an atmosphere, it will be advantageous to use an aeroplane as a construction keeping the interplanetary ship in the atmosphere. Aeroplanes, having the capability of conducting a gliding descent in case of an engine

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Fridrikh Tsander.

shutdown, are far superior to parachutes, proposed for the return to Earth by Oberth in his book “Rocket to the Planets”.

Parachutes do not offer the possibility of freely choosing a landing site or continuing the flight in case of a temporary engine shutdown, and therefore it would be advisable to use them only for flights without people. The part of the rocket that is operated by a man, should be equipped with an aeroplane. For descending to a planet having sufficient atmosphere, using a rocket, as proposed by K. E. Tsiolkovskiy, will also be less advantageous than using a glider or an aeroplane with an engine, because a rocket consumes much fuel during the descent and its descent will cost, even if there is only one person in the rocket, tens of thousands of rubles, whereas descending with an aeroplane costs only several tens of rubles, and with a glider, nothing at all.”

In this and other works Tsander expounded on the design of an interplanetary spaceplane that would reach space by using a combination of propeller, jet, and rocket engines. As the atmosphere got thinner, unneeded metallic components would move into a boiler to be melted into more rocket fuel. For propulsion during the interplanetary cruise, Tsander proposed screens or mirrors driven by solar light, early precursors of today’s solar sails.

Myasishchev’s Projects 46 and 48

Vladimir Myasishchev’s OKB-23 (situated in the Moscow suburb of Fili) was mainly engaged in the development of long-range strategic bombers, but branched out into cruise missiles with the M-40/Buran project in 1954-1957 and also did considerable research on spaceplanes even before Tsybin had started his PKA project. Unfortu­nately, most of the archival materials related to Myasishchev’s spaceplane projects have not been preserved, making it difficult to piece together their history. According to Russian historians Myasishchev, inspired by plans for the X-15 and US boost – glide concepts, began spaceplane research “on his own initiative’’ as early as 1956 under a program named Project 46. Also involved in the research were the NII-1 and NII-4 research institutes.

By 1957 he came to the conclusion it would be feasible in the short run to develop a reusable vehicle called a “satelloid’’ or “intercontinental rocket plane’’. Its primary goal would be to conduct strategic reconnaissance over enemy territory without the risk of being shot down by anti-aircraft defense means. Such missions would last 3 to 4 hours, with the spaceplane using radar and both optical and infrared photographic equipment to detect troop movements and spot enemy aircraft and missiles. Included

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Vladimir Myasishchev.

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Project 46 spaceplane (reproduced from A. Bruk, 2001).

in the early warning network would be high-orbiting relay satellites. Later goals were to send vehicles of this type on bombing missions or to destroy enemy missiles and satellites. A reconnaissance version was expected to be ready by 1963 and a combined reconnaissance/bombing version was planned for 1964-1965. Myasishchev is said to have presented his ideas for spaceplanes during a visit to OKB-23 by Khrushchov in August 1958, but the Soviet leader was unimpressed, telling Myasishchev to stick to the field of aviation and leave rocket-related matters to others.

Undeterred by Khrushchov’s scepticism, OKB-23 pressed on with its spaceplane research. By April 1959 the bureau had worked out plans for a 10-ton rocket plane flying between altitudes of 80 and 150 km and capable of increasing orbital altitude by 100 km (to a maximum of 250 km) and changing orbital inclination by 3°. As Dyna-Soar, it was envisaged as a “boost-glide” system, being launched into orbit by a conventional ballistic rocket and then gliding back to a horizontal runway landing. The launch vehicle was to be an upgraded three-stage version of Korolyov’s R-7 missile. The third stage apparently consisted of four “boost engines’’ drawing propellant from four jettisonable tanks mounted on the spaceplane itself. In April 1960 Myasishchev revised his plans and was now aiming for a 6-ton vehicle flying in 600 km orbits and capable of performing inclination-changing maneuvers of as much

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Meanwhile, OKB-23 was tasked with the development of another manned space vehicle by a government and party decree (nr. 1388-618) issued on 10 December 1959. This decree, considered to be the first macro-policy statement on the Soviet space program, encompassed a wide range of space projects. Myasishchev’s bureau in particular was assigned to develop a manned vehicle capable of ensuring “a reliable link’’ between the ground and “heavy satellites’’. Known as Project 48, this appears to have been an early version of a transportation system for space stations, although it was supposed to solve defense-related tasks as well. It was only the second piloted space project to be officially approved by a party/government decree after Vostok. Work on the project got underway after orders from the State Committee of Aviation Technology (GKAT) on 7 January and 4 March 1960.

Myasishchev’s Projects 46 and 48

48-2 spaceplane (reproduced from A. Bruk, 2001).

Weighing no more than 4.5 tons, the spacecraft was to be launched into a circular 400 km orbit by an R-7 based launch vehicle and stay in orbit anywhere from 5 to 27 hours. Re-entry through the atmosphere was to consist of a ballistic and a “controlled gliding” phase, reducing deceleration forces to no more than 3-4g. This required an aerodynamic shape providing at least some lift and ruled out a Vostok – type spherical design. Thermal protection was to be provided by ceramic tiles and/or by super-cold liquid metals circulating under the spacecraft’s skin.

Myasishchev’s team came up with four possible designs to meet these require­ments, each capable of carrying two men. Vehicle 48-1 (launch mass 4.5 tons) had a cone-shaped fuselage with highly swept delta wings (79°) and fins on the wings and fuselage to provide braking during re-entry. The crew cabin was located in the back. Both the fins and the glider’s engine compartment were to be jettisoned when the spaceplane had decelerated to a speed of Mach 5. Vehicle 48-2 (launch mass 4.3 tons) had a cylindrical fuselage with delta wings (leading edge sweepback of 65°) and small canards in the front. There were vertical tails both on top of and under the fuselage. The crew cabin was situated in the middle and the spaceplane was outfitted with a non-jettisonable engine compartment. The two other schemes envisaged a Mercury/ Gemini look-alike inverted cone with a rotor for a helicopter-type landing (48-3) and a conically shaped spacecraft for a parachute landing (48-4). Missions of the two-man ship were to be preceded by test flights of a single-seater spaceplane to demonstrate

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One version of the VKA-23 spaceplane (reproduced from A. Bruk, 2001).

the functioning of life support systems and test the “gliding re-entry” technique. The proposals were reviewed at a meeting of leading aviation specialists on 8 April I960, but no consensus was reached on the way to go forward.

There was yet another OKB-23 proposal for a single-seater spaceplane, which Myasishchev historians also link to Project 48, although it does not appear to have been the aforementioned one-man demonstration vehicle. It has been referred to as VKA-23 (VKA standing for “Aerospace Apparatus” and “23” referring to the name of the design bureau) and was the brainchild of OKB-23 designers L. Selyakov and G. Dermichov, who had originally presented it to NII-1 chief Mstislav Keldysh. Two versions of the delta-wing VKA-23 were studied between March and September 1960, one with a single fin at the rear (launch mass between 3.5 and 4.1 tons, length 9.4m) and one with two fins at the tips of the wings (launch mass between 3.6 and 4.5 tons, length 9.0 m).

The VKA-23 was to be launched either by an R-7 based rocket or a much more powerful rocket developed in-house under the so-called Project 47. In a launch emergency, the pilot could eject from the vehicle up to an altitude of 11 km, higher than that the entire vehicle would be separated from the rocket. The VKA-23 was supposed to borrow some elements from the Vostok spacecraft such as the Chayka orientation system and the Zarya communication system. Thermal protection was provided by ultra lightweight ceramic foam tiles very similar in shape to the ones later used by the US Space Shuttle and Buran. The leading edges of the wings were protected by a thick layer of siliconized graphite. A small turbojet engine was to give the ship extra maneuverability during re-entry. Just like the Vostok cosmonauts, the pilot was not supposed to land inside the ship, but eject at an altitude of about 8 km, with the spacecraft itself making an automatic landing on skids.

Although Project 48 had received the official nod with the party/government decree of December 1959, it was no longer mentioned in an even bigger space decree released on 23 June 1960. Actually, OKB-23 was counting its final days, falling victim to Khrushchov’s policy of downsizing aviation in favor of missiles. In October 1960 Myasishchev’s design bureau became Branch Nr. 1 of the OKB-52 design bureau of Vladimir Chelomey and was assigned to various missile, rocket, and spacecraft projects. Myasishchev was named head of TsAGI, but in 1967 was placed in charge of the EMZ design bureau, which would go on to play a vital role in the Buran program [20].

THE FIRST ROCKET PLANES The RP-1

Tsander did more than just generate fancy ideas. He set about turning his ideas into practice in the late 1920s with the development of an experimental rocket engine called the OR-1. In the autumn of 1931 Tsander took the initiative to establish an amateur group to study the practical aspects of rocketry and space exploration. Called the Group for the Investigation of Reactive Motion (GIRD), one of its four sections aimed to install rocket engines on gliders and thereby create a high-altitude aircraft, an idea promoted by the young engineer Sergey P. Korolyov. The engine to be used initially would be Tsander’s OR-2. Generating 50 kg of thrust, it used gasoline and liquid oxygen as propellants and had sophisticated features such as regenerative cooling of the combustion chamber using gaseous oxygen, a nozzle­cooling system using water, and a pressure feed system using nitrogen.

In early 1932 a decision was made to put the OR-2 on the BICH-11 flying wing glider. The resulting rocket plane, called RP-1, would be a modest machine, capable of developing a speed of 140 km/h, reaching an altitude of 1.5 km, and staying in the air for just about 7 minutes. However, GIRD had plans for more sophisticated rocket planes, including the RP-3, a two-man plane using a combination of piston and rocket engines to reach altitudes of 10-12 km [1].

While development of the engine got underway, Korolyov himself made several unpowered test flights of the BICH-11 to test its flying characteristics. Before tests of the engine got underway, the overworked and frail Tsander was sent to a sanatorium in the Caucasus, but contracted typhoid fever on the way and passed away on 28 March 1933 at the age of 45. His infectious enthusiasm was surely missed by the GIRD team. Korolyov’s daughter would later describe Tsander as an “adult child’’ in everyday affairs, but the “highest authority’’ in rocket matters [2]. One cannot even begin to imagine what further contributions this man could have made to Soviet rocketry had he not died such an untimely death.

Tests of the OR-2 engine in 1933 proved unsatisfactory and attempts to replace the gasoline by ethanol to facilitate cooling did not produce the expected results either. Modifying the glider to carry a rocket engine also turned out to be more difficult than expected, with one of the requirements being to drop the fuel tanks in flight to increase safety. Before the RP-1 ever had a chance to make a powered flight, GIRD was forced to change direction.

The RP-318-1

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

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The RP-318-1 rocket plane.

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.

WORLD WAR II ROCKET-PROPELLED AIRCRAFT

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.

Short-range interceptors

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

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Cutaway drawing of the BI rocket plane.

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].

Rocket-augmented aircraft

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].

POST-WAR ROCKET PLANES

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,

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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

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The Samolyot 5 rocket plane.

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.

INTERCONTINENTAL BOMBERS

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

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Soviet antipodal bomber.

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].