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Soyuz 7K-OK
Part of Soyuz
Soyuz Cutaway
Soyuz Cutaway
Cutaway of Soyuz 7K
Credit: © Mark Wade
Russian manned spacecraft. Development of a three-manned orbital version of the Soyuz, the 7K-OK was approved in December 1963. Launched 1966 - 1969.

AKA: 11F615;7K-OK. Status: Operational 1966. First Launch: 1966-11-28. Last Launch: 1970-06-01. Number: 17 . Thrust: 4.09 kN (919 lbf). Gross mass: 6,560 kg (14,460 lb). Unfuelled mass: 6,060 kg (13,360 lb). Specific impulse: 282 s. Height: 7.95 m (26.08 ft). Span: 9.80 m (32.10 ft).

The manned spacecraft became the first to complete automated orbital rendezvous, docking and crew transfer. It served as the basis for the Soyuz ferry used with the Salyut and Almaz space stations.

In the second quarter of 1963, when Korolev had begun design of the Voskhod multi-manned spacecraft, he instructed his bureau to begin design of a three-manned orbital version of the Soyuz, the 7K-OK. Korolev finally obtained approval for this spacecraft in the decree of 3 December 1963.

The 7K-OK earth-orbit version of Soyuz as developed in accordance with the decrees of 16 April 1962 and 3 December 1963 was to be capable of the following:

The 7K Soyuz spacecraft was initially designed for rendezvous and docking operations in near earth orbit. In the definitive December 1962 Soyuz draft project, the Soyuz-A appeared as a two-place spacecraft. The Soyuz would have been launched on a lunar flyby after successive launches of 11K tanker spacecraft with a 9K translunar injection stage.

Korolev understood very well that financing for a project of this scale would only be forthcoming from the Ministry of Defense. Therefore his draft project proposed two additional modifications of the 7K: the Soyuz-P (Perekhvatchik, Interceptor) space interceptor and the Soyuz-R (Razvedki, intelligence) command-reconnaissance spacecraft. The VVS and the rocket forces supported these improved variants of the Soyuz. But Korolev had no time to work on what he considered a Soyuz 'side-line'. Therefore it was decided that OKB-1 would concentrate only on development of the Soyuz-A spacecraft, while the military projects Soyuz-P and Soyuz-R were 'subcontracted' to OKB-1 Filial number 3, based in Samara.

To Korolev's frustration, while Filial 3 received budget to develop the military Soyuz versions, his own Soyuz-A did not receive the support of the leadership for inclusion in the space program of the USSR. The 7K-9K-11K plan would have required five successful automatic dockings to succeed. This seemed impossible at the time. Instead Chelomei's LK-1 single-manned spacecraft, to be placed on a translunar trajectory in a single launch of his UR-500K rocket, was the preferred approach.

Korolev finally obtained approval for development of the 7K-OK earth orbital version of the Soyuz spacecraft in the decree of 3 December 1963.

The landing capsule could accommodate a crew of up to three. It was 2.16 m long and had a diameter of 2.2 m. On re-entry it produced a hypersonic L/D ratio of 0.2 to 0.3. It was equipped with 14 translation/orientation engines; 16 orientation engines; 6 re-entry orientation engines; 4 small correction engines; and 2 rendezvous and correction engines. The 11A511 launch vehicle designed for the spacecraft had a gross lift-off mass of 308 metric tons, was 45.6 m long, 10.3 m maximum span, and had a total burn time of 538.5 seconds. The design orbit was 205 km circular at 51.68 degrees inclination. The first flight took place on 28 November 1966 and the program was completed on 31 December 1971. Spacecraft used for space station operations had indexes 7KT.

On 25 October 1965, less than three months before his death, Korolev regained the project for manned circumlunar flight. This would use a derivative of the 7K-OK, the 7K-L1, launched by Chelomei's UR-500K, but with a Block D translunar injection stage from the N1. Originally Korolev considered that the 7K-L1, for either safety or mass reasons, could not be boosted directly by the UR-500K toward the moon. He envisioned launch of the unmanned 7K-L1 into low earth orbit, followed by launch and docking of a 7K-OK with the 7K-L1. The crew would then transfer to the L1, which would then be boosted toward the moon. This was the reason for the development of the 7K-OK.

After the death of Korolev's OKB-1 was headed by his assistant, Vasiliy Pavlovich Mishin. Kozlov considered work on his military versions of Soyuz in Samara.

In June 1965 Gemini 4 began the first American experiments in military space. In August 1965, the Soviet military ordered that urgent measures be taken to test manned military techniques in orbit at the earliest possible date. Modifications were to be made by Kozlov to the Soyuz 7K-OK spacecraft for this purpose. However the first orbital launch of the 7K-OK in November 1966 a large number of failures occurred, indicating many errors in construction. The spacecraft was uncontrollable and was finally destroyed by the on-board APO destruct system.

On the second launch attempt on 14 December, the Soyuz incorrectly detected a failure of the launch vehicle at 27 minutes after an aborted launch attempt. The launch escape system activated while the vehicle was still fuelled on the pad, pulling the capsule away from the vehicle but exploding the launch vehicle and killing and injuring several people. Analysis of the failure indicated numerous problems in the escape system. In order not to inherit the problems of the 7K-OK, Kozlov's 7K-VI was completely redesigned. The final design owed little to the 7K-OK. After many twists and turns the Soyuz VI project was eventually cancelled.

As for the 7K-OK itself, after sinking to the bottom of the Aral Sea after a trouble-ridden third flight, it was taken into space by cosmonaut Komarov in April 1967. This disastrous flight ended in the cosmonaut being killed. The 7K-OK was redesigned to the extent possible and went on to accomplish 13 relatively successful manned and unmanned earth orbital flights. The 7K-OK was later modified to the space station ferry configuration 7KT with the addition of a docking tunnel. This configuration killed three cosmonauts aboard Soyuz 11 in 1971. Thereafter the spacecraft underwent a complete redesign, resulting in the substantially safer 7K-T, which flew dozens of times to Salyut and Almaz space stations until replaced by the Soyuz T in 1981.

Soyuz Guidance and Controls

The re-entry maneuver was normally handled automatically by radio command. Spacecraft attitude in relation to the local motion along the orbit was determined by sun sensors, infrared horizon sensors and ion gauges, which could detect the spacecraft's direction of motion by the greater velocity of ions impacting the spacecraft in the direction of motion.

The cosmonaut could however take manual control of the spacecraft and manually re-enter. This was done by using the ingenious Vzor periscope device. This had a central view and eight ports arranged in a circle around the center. When the spacecraft was perfectly centered in respect to the horizon, all eight of the ports would be lit up. Alignment along the orbit was judged by getting lines on the main scope to be aligned with the landscape flowing by below. In this way, the spacecraft could be oriented correctly for the re-entry maneuver.

To decide when to re-enter, in the event of loss of communications with ground control, the cosmonaut had a little clockwork globe that showed current position over the earth. By pushing a button to the right of the globe, it would be advanced to the landing position assuming a standard re-entry at that moment.

This manual system would obviously only be used during daylight portions of the orbit. At night the dark mass of the earth could not have been lined up with the optical Vzor device. The automatic system would work day or night. However problems were found on Soyuz 1 when the ion gauges would not function in ion 'pockets' of low density in the re-entry maneuver portion of the orbit.

The Soyuz kept (to this day) the little globe and Vzor system. The Soyuz 7K-OK had no on-board inertial navigation system. To perform an orbital maneuver, the parameters for an orbital maneuver would be transmitted from the ground. When the time came for a maneuver, the spacecraft would align itself to the local vertical and direction of motion by the methods mentioned above (automatic or manual). Then three gyros would be spun up, the spacecraft maneuvered automatically or manually to the required attitude for the maneuver, and the main engine would fire automatically at the prescribed time to make the orbit change. There was a simple delta-v gauge showing the velocity change. Since the Soyuz thrust to weight was so low (around 0.06, or only half a meter per second) this meant the maneuvers could be handled manually without much error (on re-entry burns the practice was to count to five after the engine was supposed to shut off before overriding it!)

The Soyuz had a very limited maneuver capability, a source of some embarrassment during the ASTP joint flight where the Apollo did most of the maneuvering. The basic Soyuz was limited to being actively controlled for only 1 to 3 hours per day; the rest of the time was spent in a passive mode.

Crew Size: 3. Orbital Storage: 35 days. Habitable Volume: 9.00 m3. Spacecraft delta v: 390 m/s (1,270 ft/sec). Electric System: 0.50 average kW.


More at: Soyuz 7K-OK.

Family: Manned spacecraft, Space station orbit. Country: Russia. Engines: KTDU-35. Spacecraft: Soyuz 7K-OK SA, Soyuz 7K-OK BO, Soyuz 7K-OK PAO. Flights: Soyuz 1, Soyuz 3, Soyuz 4, Soyuz 5, Soyuz 6, Soyuz 7, Soyuz 8, Soyuz 9. Launch Vehicles: R-7, Soyuz 11A511, N1, N1 1969. Propellants: Nitric acid/Hydrazine. Launch Sites: Baikonur, Baikonur LC1, Baikonur LC31. Agency: Korolev bureau, MOM. Bibliography: 121, 181, 185, 186, 187, 188, 2, 21, 23, 283, 32, 33, 36, 367, 376, 42, 474, 6, 60, 66, 82, 6899, 13125, 13126, 13127, 13128.
Photo Gallery

Soyuz 7K-OKSoyuz 7K-OK
Credit: © Mark Wade


Rotor SoyuzRotor Soyuz
Heavily dented model of Soyuz capsule used in test of rotor recovery system.
Credit: Jakob Terweij


Panel Soyuz 7K-OKPanel Soyuz 7K-OK
Control panel of the initial earth orbit version of Soyuz.
Credit: © Mark Wade


Soyuz OK panelSoyuz OK panel
Detail of left command panel of Soyuz OK
Credit: © Mark Wade


Soyuz 7K-OK probeSoyuz 7K-OK probe
Soyuz 7K-OK docking probe
Credit: © Mark Wade


Soyuz 4 and 5Soyuz 4 and 5
Soyuz 4 and 5 in docked configuration
Credit: © Mark Wade


Soyuz 7K-OK IconSoyuz 7K-OK Icon
Soyuz 7K-OK
Credit: © Mark Wade


Soyuz 7K-OK BottomSoyuz 7K-OK Bottom
Credit: © Mark Wade


Soyuz 7K-OK TopSoyuz 7K-OK Top
Credit: © Mark Wade


Soyuz OM panelSoyuz OM panel
Detail of orbital module command panel of Soyuz OK
Credit: © Mark Wade


Soyuz 7K-OKSoyuz 7K-OK
Credit: © Mark Wade


Soyuz escape towerSoyuz escape tower
Soyuz launch escape system - air tunnel test model
Credit: © Mark Wade


Gas dynamic tunnelGas dynamic tunnel
Gas dynamic tunnel tests
Credit: © Mark Wade


Soyuz OM interiorSoyuz OM interior
Interior view of Soyuz 4 orbital module (through open side hatch)
Credit: Andy Salmon


Soyuz OPSSoyuz OPS
Soyuz escape tower (as used on early Soyuz launches)
Credit: Andy Salmon


Soyuz 7K-OK SideSoyuz 7K-OK Side
Credit: © Mark Wade


Soyuz orbital moduleSoyuz orbital module
Soyuz 7K-OKS passive docking orbital module
Credit: Andy Salmon


Soyuz control panelSoyuz control panel
Soyuz orbital module control panel
Credit: © Mark Wade


Soyuz 7K-OK BOSoyuz 7K-OK BO
Soyuz 7K-OK Orbital Module with female docking unit
Credit: © Mark Wade


Soyuz 1Soyuz 1
Credit: Manufacturer Image


Soyuz 9Soyuz 9
Credit: Manufacturer Image


Soyuz 2Soyuz 2
Credit: Manufacturer Image


Soyuz 6Soyuz 6
Credit: Manufacturer Image


Soyuz matedSoyuz mated
Soyuz spacecraft being mated to the booster upper stage.
Credit: RKK Energia


Soyuz OK PanelSoyuz OK Panel



1963 March 7 - . LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1963 March 21 - . LV Family: N1. Launch Vehicle: N1 1964.
1963 December 3 - .
November 1964 - .
1965 August 18 - .
1965 August 28 - .
1965 September 22 - .
1965 October 25 - . Launch Vehicle: Proton.
1965 November 24 - .
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1965 December 4 - .
1965 December 31 - . LV Family: N1. Launch Vehicle: N1 1964.
1966 January 6 - .
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1966 January 14 - . Launch Vehicle: N1.
1966 January 24 - .
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1966 July 22 - . LV Family: N1.
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1966 November 18 - . Launch Vehicle: N1.
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1966 November 28 - .
1966 November 28 - . 11:00 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1966 November 29 - .
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1966 December 1 - .
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1966 December 14 - .
1966 December 14 - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511. FAILURE: Erroneous firing of launch escape tower ignited launch vehicle on the pad.. Failed Stage: P.
1966 December 15 - .
1966 December 16 - .
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1966 December 23 - .
1966 December 24 - . LV Family: Proton. Launch Vehicle: Proton-K.
1967 January 5 - .
1967 January 17 - .
1967 February 7 - . 03:20 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC1. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1967 March 12 - .
1967 March 16 - .
1967 March 20 - .
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1967 April 1 - .
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1967 April 14 - .
1967 April 16 - .
1967 April 20 - .
1967 April 23 - . 00:35 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC1. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1967 April - .
1967 April 27 - .
1967 May 5 - . LV Family: N1, Proton, N11.
1967 May 7 - .
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1967 October 4 - . LV Family: N1.
1967 October 6 - .
1967 October 7 - . LV Family: Proton. Launch Vehicle: Proton-K.
1967 October 16 - .
1967 October 17 - .
1967 October 23 - .
1967 October 24 - .
1967 October 27 - . 09:29 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1967 October 29 - . Launch Vehicle: N1.
1967 October 30 - . 08:12 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC1. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1967 October 31 - .
1967 November 1 - .
1967 November 4 - .
1967 November 5 - .
1967 November 16 - .
1968 January 26 - .
1968 February 21 - . LV Family: Proton. Launch Vehicle: Proton-K/D.
1968 March 7 - .
1968 March 25 - .
1968 March 26 - .
1968 April 14 - . 10:00 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1968 April 15 - . 09:34 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC1. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1968 April 20 - .
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1968 July 3 - .
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1968 August 28 - . 10:00 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1968 September 21 - .
1968 September 23 - .
1968 September 28 - .
1968 October 1 - .
1968 October 5 - .
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1968 October 15 - .
1968 October 20 - .
1968 October 25 - . 09:00 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC1. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1968 October 26 - . 08:34 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1968 October 27 - .
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1969 January 13 - .
1969 January 14 - . 07:30 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1969 January 15 - . 07:04 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC1. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1969 January 16 - .
1969 January 16 - . 12:43 GMT - .
1969 January 19 - .
1969 January 29 - .
1969 January 31 - .
1969 February 10 - .
1969 March 20 - . Launch Vehicle: N1.
1969 March 28 - .
1969 April 19 - .
1969 April 26 - .
1969 May 10 - .
1969 June 9 - .
1969 August 26 - .
1969 September 1 - .
1969 September 18 - .
1969 September 24 - .
1969 September 27 - .
1969 October 11 - . 11:10 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1969 October 12 - . 10:44 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC1. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1969 October 13 - . 10:19 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1969 October 14 - .
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1969 October 23 - .
1969 December 30 - .
1970 February 2 - .
1970 February 14 - .
1970 May 18 - .
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1970 May 26 - .
1970 May 30 - .
1970 May 31 - .
1970 June 1 - . 19:00 GMT - . Launch Site: Baikonur. Launch Complex: Baikonur LC31. LV Family: R-7. Launch Vehicle: Soyuz 11A511.
1970 June 2 - .
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1970 July 16 - .
1970 July 30 - .
1970 December 13 - .
1972 January 1 - .
1972 June 16 - .
1972 June 16 - .
1974 June 24 - . Launch Vehicle: N1.

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