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Development of the Spiral space plane

The Soviet concept of a multipurpose manned space plane emerged in the heat of the Cold War, at the end of the 1950s - and beginning of the 1960s. Research in the field was pioneered by design collectives led by Myasishev and then by Chelomei. However, in 1964, Chelomei -- guilty by association with then deposed Soviet leader Nikita Khrushchev -- fell out of favor with the new Soviet government. As a result, by 1965, the main effort in the field of space planes shifted to Artem Mikoyan's OKB-155 design bureau, world-renown for its fearsome MiG fighter jets. There, the Spiral project was born. Typically for the time period, this work mirrored projects of American hypersonic and orbital planes, such as the X-15 and Dyna Soar.


Organization of the program

Within Mikoyan's OKB-155 design bureau, Gleb Lozino-Lozinskiy was appointed chief designer of the Air-Orbital Plane, VOS (from Russian Vozdushno-Orbitalniy Samolet), also known as System 50/50 or Aerospace System, AKS. (The designation "Spiral" was later applied to the orbital stage itself.)

S. G. Frolov was assigned to represent a client -- the Soviet Air Force. Z. A. Yoffe, the chief of the TsNII-30 research institute of the Air Force, led the military-engineering supervision of the program, along with his deputy for science V. I Semenov and chiefs of directorates V. A. Matveev and O. B. Rukosev, who together were responsible for the formulation of the concept.

Along with TsNII-30, a number of key organizations of the Ministry of Aviation Industry, MAP; General Machine Building, MOM; Radio Industry, MRP; MOP, MEP and MO also participated.


The Spiral was conceived as an "orbital fighter," capable of active maneuvering and attacking targets in space and on the ground. (319)


Developers proposed to use the Spiral space plane to do three main jobs:

The reconnaissance version of the Spiral would carry a photo-camera with a resolution of 0.75-1 meter and radar payloads to conduct on-demand spy missions over the Earth's surface;

The bomber version would be equipped with orbit-to-surface missiles, capable of hitting targets on Earth;

The interceptor version would be capable of inspecting and destroying targets in space.

For all three applications, the Spiral would have to compete in performance with unmanned military satellites. At the time the Spiral was conceived, the jury was still out on which type of vehicle would be better suited for the job. Due to the claimed cost-efficiency of the Spiral system, the replacement of unmanned payloads with the manned space plane, formed an ideal flexible, fast-response launch vehicle system.


As a preliminary step in the development of the orbiter, engineers conceived a full-scale prototype, known as the Experimental Piloted Orbital Plane, or EPOS in Russian. The 6.8-ton vehicle could still reach a 150-160-kilometer orbit with an inclination of 51 degrees, after a launch on top of an R-7-based rocket from Baikonur. EPOS could also change the inclination of its orbit by as much as 8 degrees.

Even before EPOS, a number of full-scale prototypes launched from a Tupolev-95 strategic bomber were deemed necessary to tackle numerous problems of aerodynamics, attitude control with the use of gas thrusters and the flight control systems. A total of three such prototypes were planned for tests at three major phases of reentry speed:

  • The 105.11 vehicle for subsonic flight tests;
  • The 105.12 vehicle for supersonic flight tests;
  • The 105.13 vehicle for hypersonic flight tests;

Two latest versions of EPOS would have the exact geometric shape, internal structure and thermal protection system envisioned for the final design of the Spiral orbiter. However unlike the final configuration, the 105.12 and 105.13 versions would be equipped with a pair of rocket engines with a thrust of 13 tons each. This would enable the vehicles to accelerate to a speed 6 - 8 times the speed of sound (Mach 6-8) after its separation from the Tu-95 bomber. Following this mid-air drop, it could reach an altitude of 50-120 kilometers.

The prototypes would have a mass of up to 12 tons and carry up to 7 tons of propellant. The latest version could fly up to 6-8 Mach and climb up to 120 kilometers. (317)

The EPOS prototype had to meet the following system requirements:

  • The temperature of its external surfaces could not exceed 1,400 degrees;
  • During the reentry, the vehicle had to maintain an angle of attack between 45 and 65 degrees with necessary stability along the flight path;
  • Landing of the vehicle should not be different from a normal touchdown of a regular aircraft;
  • The vehicle had to provide a maximum volume with minimum air resistance;
  • The size of the vehicle should enable its launch on a 11A511 (R-7-based) Soyuz rocket with appropriate modifications;
  • The orbiter would be equipped with swept wings capable of rotating along the main axis of the vehicle;

A special truss would serve as an internal skeleton of the orbiter, supporting all key elements of the vehicle's structure, including its heat shield, cabin, equipment containers, wings, vertical stabilizer, landing gear and engines. The truss would carry all of the loads impacting the fuselage. The heat shield would be attached to the truss at the bottom via special hinges, enabling its movements relative to the rest of the spacecraft body and designed to minimize the transfer of heat during the reentry.

The landing gear was designed to avoid any openings in the heat shield of the vehicle, as well as wheels under pressure. While the final version of the orbiter was to be equipped with ski-like landing gear, the subsonic prototypes of the craft would feature regular wheels with individual brakes on each wheel.

The propulsion system of the orbiter included a main liquid-propellant engine with a thrust of 1,500 kilograms.

Development of the orbiter


Shown here is an artist rendering of the Spiral orbiter based on actual blueprints of the vehicle. Previous Western depictions of the vehicle were largely inaccurate since they had to be modeled after its subsonic prototype. During the orbital phase of its flight and most of the reentry, the ship's wings would be in a nearly vertical position, contrary to the "normal" horizontal position shown in many visualizations. Copyright © 2008 Anatoly Zak

During 1964 and 1965 experts at TsNII-30 developed a concept of the so-called air and space system or VKS. On June 29, 1966, or about a year after the start of the effort, Lozino-Lozinskiy singed a preliminary design document ("avant project") of the Spiral system. In the same year, the leading Soviet institute in the field of aviation science, TsAGI, initiated research into the fundamentals of reusable hypersonic vehicles. (318)

The program envisioned the following phases:

1. The development of three increasingly complex prototypes of the orbiter to test techniques of reentry and landing and capable of flying at Mach 6 to Mach 8 following a launch from the Tu-95 carrier aircraft;

2. The development and launch of the unmanned and manned experimental prototype EPOS of the Spiral vehicle into the orbit onboard of a R-7-based Soyuz rocket.

3. The development of three versions of the Spiral orbiter, for reconnaissance, bombing of targets on Earth and anti-satellite roles;

4. The development of a specialized GSR booster aircraft, with turbo-jet and ram-jet engines. (318)

5. The final integration of the OS orbiter, and the GSR booster aircraft into the final VKS aerospace system. (317)

TsAGI confirmed the validity of the orbital space plane development program in a special "Conclusion" document issued in April 1966. (318)

To implement the development of the aerospace vehicle, a branch of Mikoyan design bureau was created in the town of Dubna on April 25, 1967. It was led Mikoyan's Deputy Designer Chief P. Shuster, while the design bureau within the branch was led by Yu. Blokhin and D. A. Reshetnikov who was responsible for the branch's production. A number of specialists came to the branch from MKB Raduga. The Branch also established contacts with the Cosmonaut Training Center, TsPK, in Star City, which would assist the organization in the development of the flight control systems. (317)

Along with aerodynamic research of the hypersonic vehicle, TsAGI supported the Spiral project with the development of a simulator, which enabled to development of the orbiter's flight control system. For this purpose, TsAGI received a full-scale mockup of the orbiter's cabin to test its emergency escape system. The same hardware also became a base for the MK-10 simulator, which was used during 1969-1972 to test piloting of the vehicle. This work was used to develop the design of the flight control system. The work further expanded by 1976, when the Pilot 105 research complex was inaugurated in Star City. To add extra realism, the new simulator was mounted inside Star City's TsF-7 centrifuge.

Development of the GSR

From 1965 to 1957, scaled models of two versions of the GSR aircraft went through wind tunnel testing at the TsAGI research institute in Zhukovsky, near Moscow. The most advanced phase of the work was the development of methods to test airflow through the propulsion system intake nozzle at hypersonic speed. Wind tunnel tests confirmed the validity of the main concept. (317)

Fundamental research

In the course of the Spiral project, developers formulated general requirements for the aerodynamic shape of the vehicle and its aerodynamic and gas-dynamic control systems. Various flight trajectories, flight modes and flight control problems were analyzed, including the possibility of landing the vehicle in gliding unpowered flight.


In 1967, the LII Flight Research Institute, initiated studies which led to the Bor-2 and Bor-3 vehicles. Launched by expendable rockets, they were essentially scaled prototypes of the Spiral orbiter, aimed to test a "lifting body" at speeds from Mach 3 to Mach 14.

The Spiral project was concluded in 1977 - 1978 with a series of flights of a subsonic prototype of the vehicle, after it was dropped from Tupolev-95 aircraft. (317).

Still, from 1977, the 1,500-kilogram Bor-4 model, representing one half scale version of the Spiral orbiter, was under development. Like the "real" Spiral, Bor-4 could rotate its wings, and, while beyond the atmosphere, eight thrusters could be used to maintain the attitude control. A special version of the Cosmos-3 rocket, known as K-65-RB-5, would send Bor-4 on a single-orbit flight, after which, it would glide to a splashdown in the Indian Ocean or the Black Sea. (317)

Although the Spiral project reached the experimental stage, it had never been formally approved by the Soviet government for full-scale development. By 1976, the USSR had embarked on the development of the equivalent of the US Space Shuttle, later known as the Energia-Buran program, essentially making the Spiral project redundant. The project was ultimately shot down in 1978.

Chronology of the Spiral project:

1962: Chief Commander of the Soviet Air Force, K. A. Vershinin wrote to the head of TsAGI Myasishev among other organizations to promote research of orbital and aerospace vehicles. (318)

1964-1965: Mikoyan's OKB is given overall responsibility for the development of the aerospace system. Gleb Lozino-Lozinskiy is appointed Chief Designer of the Spiral system. (317)

1964-1965: TsNII-30 developers a general concept of the aerospace system. (318)

1965: TsNII-30 initiated preliminary studies of a lifting-body vehicle within the Spiral project.

1966 April: TsAGI confirmed the validity of the orbital space plane development in a special "Conclusion" document. (318)

1966 June 15: The decree of the Aviation Industry Ministry, MAP, appoints Gleb Lozino-Lozinskiy a Chief Designer of the VOS Spiral. (319)

1966 June 29: Lozino-Lozinskiy signs a preliminary design document for the Spiral system. (317)

1966 Aug. 2: Lozino-Lozinskiy is appointed Chief-Designer of Stage II of the VOS Spiral system. (319)

1967 April 25: A branch of Mikoyan's design bureau was created in the town of Dubna with the focus on the Spiral project. (317)

1968: Delivery of technical documentation for manufacturing of the first 105.11 prototype of the Spiral orbiter at the Dubna machine-building plant. (317)

1969-1972: Development of the MK-10 full-scale piloting stand of the Spiral orbiter at the TsAGI research institute. (317)

1967-1974: Flight testing of aerodynamic characteristics of lifting-body vehicles using Bor-2 and Bor-3 scaled versions of the orbiter. (317)

1972: Minister of Defense, A. A. Grechko refuses to coordinate the completion of the draft-decree for the Spiral development.

1972: The US government authorizes development of the reusable Space Transportation System, (Space Shuttle) (317)

1977-1978: A series of flights of a sub-sonic prototype of the Spiral orbiter.

1978: The end of the Spiral project.


Development contractors in the Spiral project:

Mikoyan KB
System integrator
Dubna machine-building plant
N. P. Fedorov
Manufacturing of the full-scale prototypes (The 105.11 version)
TsNII-30 Air Force
    Concept development
TsPK, "Star City"
Star City   Training systems
Zhukovskiy   Aerodynamic research, training hardware
-   Research in thermal dynamic, flight control of flying prototypes
NII Thermal Processes
-   Thermal dynamics calculations
TsNII of Aviation Material Science
-   Thermal dynamics calculations
NII of Aviation Systems, NIIAS
-   Thermal dynamics calculations
Moscow Institute of electromekhanics and automatics
-   Development of navigation and flight control systems
-   Radio system of navigation and landing
-   Trajectory measurement system
-   Information display system
PMZ Voskhod
-   Autonomous steering system
MPKB Voskhod
-   Air-speed parameter system
UPKB Detal
-   Altimeter system
TMKB Soyuz
-   Attitude control thruster system
Gorky Aviation Plant
-   Landing gear for the orbiter prototype


Writing, photography and illustrations: Anatoly Zak; Last update: May 23, 2020

Last edit: November 20, 2008

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In 1951, Artem Mikoyan's OKB-155 design bureau formed Branch 2 (later MKB Raduga) in the village of Ivan'kovo near the town of Dubna to produce the KS-1 Kometa anti-ship missile. Aleksandr Berezhnyak was appointed a head of the new organization, where the core of the future Spiral team would form. Click to enlarge. Copyright © 2008 Anatoly Zak

Scale model of the Spiral system in launch configuration. Click to enlarge. Copyright © 2001 Anatoly Zak


Equipped with its own air-breathing engine, the Spiral orbiter would be capable of a wide range of maneuvers during its descent from orbit. Click to enlarge. Copyright © 2008 Anatoly Zak


Artist rendering of the Spiral orbiter approaching the runway. Click to enlarge. Copyright © 2008 Anatoly Zak


Artist rendering of the Spiral orbiter touching down on the runway. Click to enlarge. Copyright © 2008 Anatoly Zak


The Spiral orbiter in landing configuration. The vehicle was designed to touch down on a conventional runway. Click to enlarge. Copyright © 2008 Anatoly Zak