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Design of Voskhod-2

The main difference of Voskhod-2 from the original Voskhod was an inflatable airlock dubbed Volga. All previous engineering attempts to fit a hard-body structure into the payload fairing envelope were unsuccessful. (18)


An equivalent of the Voskhod-2 interior looking toward the airlock entrance with the EVA hatch open, but cosmonaut chairs are apparently in upper position for landing.

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Planned parameters for the Voskhod-2 mission:

Planned launch date
First quarter of 1965
Launch vehicle
Orbit parameters
180 by 400 kilometers, inclination 65 degrees toward the Equator
Planned flight duration
One day
Maximum flight duration
Three days
Primary crew
Pavel Belyaev, Aleksei Leonov
Backup crew
V. Gorbatko, Ye. Zaikin, Evgeni Khrunov
Spacecraft mass
5,685 kilograms (84, 137); 5,682 kilograms (2)
Airlock length when deployed
2,500 millimeters
Airlock length when folded
740 millimeters
Airlock external diameter
1,200 millimeters
Airlock internal diameter
1,000 millimeters
Hatch diameter from descent moddule to the airlock
650 millimeters
Planned spacewalk duration
10 minutes

Airlock design


Volga airlocks shown under assembly at Factory No. 918 in Tomilino, near Moscow.

The folded cylindrical structure of the Volga airlock, built at Factory No. 918 near Moscow, was mounted on the exterior of hatch No. 3. The transfer hatch with an opening of 700 millimeters would open into the capsule toward the parachute container in the upper section of the module. In turn, the Vzor navigation window was built into the new hatch. Additionally, the Vzor window had a protective transparent cover on its exterior.

On its outer end, the airlock had another 700-millimeter hatch, which would also open inwards, ensuring that the internal pressure could help keeping it closed and pressurized after the spacewalk. Both hatches could be operated remotely with an electric drive or closed manually if needed.

The outer diameter of the airlock was 1.2 meters and the internal diameter was one meter. In folded position, the airlock had a length of 740 millimeters and when fully extended it would be 2.5 meters long.


The outer hatch of the Volga airlock in closed (left) and opened position.

A special console perated by a commander inside the Descent Module controlled and monitored all the operations of the airlock. It had the switches for all operations and the indicators for the key functions of the airlock and the spacesuit. A backup control switchboard, to be used in emergency, was located inside the airlock, about midway between its hatches.

During the EVA, the cosmonaut's pulse, breathing frequency, the pressure in the spacesuit, the pressure in the airlock, the backpack, the ventilation system and the oxygen supply would be all continuously measured and displayed on the commander's console. Both crew members could communicate over the phone system. (84)

The process of opening the hatch was tested under differrent pressure levels inside the airlock to establish its capabilities. The airlock was also tested inside a vacuum chamber.

The top exterior section of the airlock was crowned with a railing structure, which would be used by the spacewalking cosmonaut.


Key components of the 3KD spacecraft under assembly (left to right): the Volga airlock, the Descent Module and the Instrument Module.

The inflatable middle portion of the Volga airlock was formed by 40 dual-layer resin tubes (informally known in Russian as "dutiki") grouped in three isolated sections to ensure reliability. The operational pressure inside the air tubes was 0.65 atmospheres. On the exterior, the airlock was covered with thermal insulation. (84)

The cosmonaut could go as far as 5 meters from the spacecraft.

The airlock would be jettisoned before reentry. The main separation system of the airlock was backed up with a special rope with a pyrotechnic system.

A pair of TV cameras were used to monitor the cosmonaut outside the spacecraft. They transmitted images to a monitor inside the cabin and to the ground stations. Just before the EVA, the commander, using the manual attitude control system, was expected to orient the spacecraft to ensure good illumination by the sun. The program also called for filming the cosmonaut entering the airlock, exiting the spacecraft and returning.


A folded airlock is being installed on the hatch No. 3 of the 3KD spacecraft.

Other new systems aboard Voskhod-2

Inside the Voskhod, the cosmonauts' chairs were lowered from their operational landing position, thus providing more space in the cramped compartment during boarding of the spacecraft on the launch pad and during the transfer of the cosmonaut into the airlock. The chairs would be brought to an upper position only at the time of parachute release during the descent. (137)


Next chapter: Berkut spacesuit


The article and photography by Anatoly Zak; Last update: April 1, 2020

Editor: Alain Chabot; Edits: March 18, April 1, 2020

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An official contemporary depiction of the Voskhod-2 spacecraft. Credit: RKK Energia


A museum replica of the Voskhod-2 airlock. Copyright © 2009 Anatoly Zak


The Voskhod-2 development program included testing of the emergency separation of the Volga airlock during a potential launch failure. Credit: RKK Energia


Volga under assembly. Click to enlarge. Credit: RKK Energia


Specialists tested the ability of the Volga's hatch to hold pressure using a special mockup of the airlock filled with helium and air mixture. Click to enlarge. Credit: RKK Energia


Specialists at Factory No. 918 install the railing assembly on top of the Volga airlock. Credit: RKK Energia


Deployment test of the Volga airlock. Click to enlarge. Credit: RKK Energia


View inside the Volga airlock. Click to enlarge. Credit: RKK Energia


During most of the flight aboard Voskhod-2, the chairs would be in lower position (right), but they would be brought into an upper position (left) for landing. Credit: RKK Energia


Voskhod-2 under assembly. Click to enlarge. Credit: RKK Energia