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Sokol KV-2 rescue suit

The Sokol KV-2, «Сокол КВ-2» (“Falcon”) crew rescue suit was first worn in the Soyuz T-2 spacecraft on 5 June, 1980, and is still worn by crews today during launch and descent. Each suit is connected to an on-board life support system which supplies oxygen, electrical power, suit ventilation and water for the cooling garment worn underneath. It is considered part of the Soyuz life support system, KSOZh, КСОЖ. Each suit is tailor-made to fit individual crew members. In the Soyuz spacecraft they recline in Kazbek-U, «Казбек-У», seats which have custom-fitted molded liners.

The Soyuz is constructed of two layers: an internal and external. The internal part is made of an elastic-type material and keeps the suit pressurized. The external layer is made of a flame-resistant fabric called “Lavsan” or “Dacron”. The suit, including the helmet, is integrated; only the gloves are put on separately. The helmet has a soft cover and folds back when the wearer is upright; it can only fit over his head when he is lying in the aforementioned knees-up position.

The wearer climbs into the suit via the zippered front opening; into the legs first, then arms and head. The suit is then sealed by means of the “appendix,” flaps of cloth bound up by rubber bands. The wearer is fitted with biomedical sensors next to his skin. The blue knob on the front is a pressure regulator.

Unlike the Orlan, the Sokol does not have its own self-contained life-support system, but is connected to that of the Soyuz. It is thus not a “spacesuit” but a rescue, survival or pressure suit. There are four connections:

A mechanical regulator keeps the pressure inside the Sokol constant.

The Sokol is not particularly comfortable to walk around in due to its internal wiring and lack of ventilation (the wearer has to carry their own ventilator to avoid overheating). It is essentially designed to fit in the Kazbek chair, on one’s back with the knees up.

Some extracts:

After manufacture of the flight suit, every crew member occupies the Kazbek seat with its custom-fitted couch liners and sits in the flight posture under positive pressure for 2 hours (under ground conditions). The suit is readjusted or upgraded by the outcome of this. The next stage of suit evaluation is repetition of the same procedure in the vacuum chamber, with simulation of oxygen supply to the suit helmet. The final stage of suit evaluation is the suit fit check at Baikonur prior to the mission, and spending time in the descent vehicle cabin of the real spacecraft. The final suit check and its preflight operation are carried out at the same time. These activities (at Baikonur) are carried out by a special Zvezda team …

All spacecrews undergo extensive suited training at the Gagarin Cosmonaut Training Center (Star City), besides the activities at Zvezda. The training includes time in the Soyuz spacecraft simulator where a number of unusual situations are simulated: surviving in uninhabited areas after landing, or in case of an unexpected splashdown of the spacecraft, learning to survive in the open ocean.

Zvezda has developed special ground support test equipment and a set of fixtures for preflight testing. The suits are ventilated with air supplied from cosmodrome ground sources during fit checks at Baikonur. To ventilate the spacesuits while the cosmonauts go to the launch pad, special portable ventilation units, PVU, ПВУ, were developed. They include a fan that takes in the ambient air in and supplies it to the suit and a self-contained electrical power source. The PVU comes complete with a heat exchanger that cools supplied air with ice (put into the heat exchanger prior to its usage). It should be noted that Zvezda has used these units since the Voshkod-2 mission.

– Source: Russian Spacesuits.

The Sokol KV-2 (Falcon) pressure suit, is white nylon canvas with royal blue trim. It has an attached pressurized hood with hinged plastic visor securing to blue anodized aluminum clavicle flange, trussed sleeves with adjustable articulating cables in upper arm and webbed belt lashings, pressure gauge on left sleeve covered by protective gasket, mirror on elasticized wristband (right wrist), detachable gloves, double-V-front zip closure, lace-up crotch with triangular placket, anodized aluminum umbilical interfaces on body for electrical, air and coolant line with attached cables and hoses, pressure equalization valve on chest, support sling wrapping from chest to back by means of webbed belts and metal clips, adjustable metrically calibrated webbed straps attached to metal rings on side seams and along crotch, pleated knees, two utility pockets on each leg, attached soled feet; rubberized cloth lining. […]

Source: Smithsonian Sokol spacesuit exhibit.

Technical data

Sokol technical data
Official name Sokol KV-2 rescue spacesuit, «Сокол КВ-2»
Description The Sokol KV-2 spacesuit is connected to an on-board open-type ventilation system and is designed to provide a cosmonaut with normal hygienic conditions during a flight in a pressurized cabin and to support a cosmonaut’s vital functions in case of cabin depressurization. The suit is of the soft type with a two-layer enclosure (the outer restraint layer is made of fabric and the internal pressure bladder of rubber and a rubberized material). The helmet has a soft nape part and a sliding visor and is an integral part of the suit enclosure. Differences between Sokol K and Sokol KV-2: the lacing on the front opening is replaced by two zippers; helmet and, thus, visor dimensions are increased; the pressure regulator is integrated with an in-leakage valve and is arranged in the centre of the body under the helmet (it is located at the side on the Sokol K suit). In case of cockpit depressurization, pure oxygen is supplied to the suit. The pressure regulator provides two suit pressure modes.
Utilization (operations) The suit was first used by cosmonauts Yu. Malyshev and V. Aksionov in 1980 aboard the Soyuz T-2 space vehicle. Suits have been used for all Soyuz T, Soyuz TM and Soyuz TMA vehicles. The suits are delivered to the ISS aboard the Space Shuttle for each crew member and are intended to support a possible emergency descent aboard the Soyuz TM or Soyuz TMA vehicles.
Development and operation dates
  • Development and tests: 1973-1979
  • Nominal operations: 1980-up to the present
Technical characteristics The suit provides the cosmonaut with:
  • time of suited crew stay in a pressurized cabin for up to 30 hr;
  • time of suited crew stay in a depressurized cabin for up to 2 hr;
  • spacesuit operating positive pressure of 400 hPa (main mode) and 270 hPa (back
    up mode);
  • ventilating air flow from the on-board fan of ≥150 standard 1 min−1;
  • oxygen flow rate of 20 standard 1 min−1;
  • spacesuit mass of −10 kg.
Quantity of manufactured spacesuits (as at 31 December 2002)
  • Test and training models: 63
  • Flight models: 220
«Sokol-KB-2» Space Suit Operational Limits and Characteristics
Technical Characteristics Values
Time for crew stay in suit: ventilation ON, helmet open, gloves doffed (nominal operation) in 3-6 hr cycles 20 hrs
Time for crew stay in suit: ventilation ON, helmet open, gloves doffed (emergency operation) incl. 30 hr continuous operation 50 hrs
Time for crew stay in suit: ventilation ON, helmet closed, gloves donned 1 yr
Time for crew stay in suit: ventilation OFF, helmet open, gloves donned 1 hr
Life support time in case of CA depressurization 125 min
Life support time in case of CA depressurization using ПхО O2 stowage tanks (pre-separation) 90 min
Life support time in case of CA depressurization using CA O2 stowage tank (post-separation) 35 min

SoyCOM: Скафандр “Сокол-КВ-2” (СКФ) (“Sokol-KB-2” spacesuit)

Spacesuit purpose

The “Sokol-KB-2” spacesuit is the principal element of the КИЗС Individual Protective Equipment Set which is a part of the Soyuz spacecraft KCC Survival Aid Complex.

The “Sokol-KB-2” spacesuit is designed for maintaining life and operation support of the Soyuz crew in cooperation with spacecraft systems in case of the CA Module depressurization in critical flight phases (launch/orbit injection, docking/undocking/redocking and descent).

The КИСЗ Set jointly with the KCC Complex makes it possible to prevent the low pressure effect on the crew in case of the CA depressurization maintaining pressure in the spacesuit about 300 mm Hg by continuous oxygen supply.

In case of the CA splashdown landing after the crew egress the spacesuit ensures a crew member water buoyancy and stability by means of the “Neva-K” buoyancy collar and a capability of lifting him up on board hovering helicopter.

The KCC Complex which includes the КИЗС Set is designed for maintaining the crew life support parameters within the limits ensuring the crew safe return in case of the CA depressurization during launch/orbit injection, docking, undocking, redocking and descent flight phases. In that case the KCC issues emergency signals to the ПК СА Panel, automatically supplies oxygen to the spacesuits, prevents the CA atmosphere from overoxydation, equalizes the CA and environment pressure, switches on spacesuit fans during descent and relieves pressure from the CA oxygen tank prior to landing.

Spacesuit composition

The spacesuit set includes:

The spacesuit auxiliary equipment set includes:

The spacesuit spare equipment set for the Soyuz spacecraft includes:

The maintenance kit is designed for the spacesuit flight maintenance as its nominal usage procedure and includes:

The maintenance kit is located in the БО Module, fixed to the wall near the “Сервант” (Servant).

Besides the “Sokol-KB-2” spacesuit the КИЗС Set includes:

Spacesuit design

The spacesuit has soft type structure and is a two layer combination garment with built in soft helmet, footgear and removable gloves.

The spacesuit principal diagram is shown in Fig. 1.

There is an opening in the front part for the spacesuit donning, on the left hand cuff the pressure differential indicator is fixed and on the right hand cuff there is a removable mirror for the donned spacesuit ext erior inspection (in particular for checking up the helmet locks).

The spacesuits are manufactured for standard sizes and for basically seated position for the cosmonaut comfort in the spacecraft seat. In order to allow for a cosmonaut specific anthropometric features individual fitting aids are provided.

The spacesuit consists of two shells: internal pressure-tight envelope and external structural shell.

Pressure-tight envelope

The pressure-tight envelope is designed to ensure the spacesuit pressurization and is made of rubberized capron fabric and in the joint areas – of rubberized knitted fabric.

There is a “big appendix” in the envelope (for the spacesuit donning) and a “small appendix” in the lower part (for urination). The “appendices” are made of rubberized cotton fabric and are pressurized by means of two rubber tight plaits.

Fixed to the pressure-tight envelope internal part are elastic pipelines for ventilation and for oxygen supply. Ventilation pipelines are laid to the trousers, sleeves and helmet. Pipelines feeding air to the feet are connected to the ventilation insoles. The oxygen supply pipe is laid to the helmet.

A neck curtain is pasted in the throat part of the envelope in order to prevent water from leaking into the suit when the cosmonaut is floating. In the initial position the curtain is stowed under a cover which is attached to the envelope throat by means of a drawstring. In case of a splashdown landing the cosmonaut pulls the drawstring and the curtain is released and then by pulling the curtain band ends he tightens the neck curtain The pressure-tight envelope is attached to the structural shell.

Structural shell

The structural shell is designed for maintaining the spacesuit shape under differential pressure and for the pressure-tight envelope protection. The shell is made of lavsan fabric and has built in structural bands with clasps in the sleeves, top part, and trousers area for the spacesuit fitting.

The spacesuit is donned through the structural shell opening which is covered by means of two structural zippers. The “big appendix” is fabric-reinforced along the zippers to prevent it from jamming.

In the “small appendix” area there is a physiological opening in the shell which is secured by lacing it up and covered by a fabric flap with velcro fastener.

The spacesuit frontal opening is reinforced by a transversal structural band which locks the shoulder joint cords and by a spring lock in the waist area.

In order to provide for the spacesuit mobility freedom there are soft joints in the structural shell shoulder, elbow and knee areas. The shoulder joints are additionally equipped with cord connections for a better mobility.

There is an adjustable frontal tightening band with a spring lock used to compensate for eventual spacesuit excess stretching out by the pressure differential.

Pressure-tight helmet

The pressure-tight helmet is manufactured integral with the spacesuit top and consists of the following elements:

The helmet is tightly locked when its two half-frames get in full contact. The pressure-tight joint is fixed closed by means of two locks located on the helmet lower half-frame. At the moment of each lock closing its latch actuates and a specific click is heard.

The latch has a mechanical flag indicator which is protruding from the lock body in case it is not fully closed.

The helmet is unlocked by rotating the lower half-frame handle down and to the right up to the limit. This will move the lower half-frame arch until its bosses contact the latch and release them from the upper half-frame hooks.

There are ventilation and oxygen manifolds in the helmet for air and oxygen supply accordingly. The ventilation manifold has a receptacle for fixing the suit pressure charging. This operation is accomplished when the cosmonaut is floating after the splash-down landing and the neck curtain has been tightened. The helmet glass is made of strong polycarbonate material with yet a decreased abrasion resistance. To prevent the glass from scratches on the outside surface it is covered with the organic glass protector which is taken off after the crew ingress prior to launch.

ГП-7А pressure-tight glove

The ГП 7А glove is a rubber pressure-tight glove which is covered by fingerless structural shell with lock ring for connection to the suit sleeve.

The rubber glove consists of a finger part and the cuff part attached to it. The finger part has the capron knitwear reinforcement layer covered with rubber. At the finger flexion points there are bulges made for finger mobility enhancement. The cuff part is made of rubberized knitwear. The structural shell is made of lavsan fabric. The glove is connected to the suit cuff by means of the lock ring in which a hollow rubber hose (the “дутик”). The glove can be rotated about the longitudinal axis by the turnable hand connector at the suit sleeve.

The pressure-tight gloves are manufactured in three sizes: III, II Б and IV which correspond to the palm half-grip of 8, 8.5 and 9 cm.

To provide necessary physiologic/hygienic conditions for the crew member operation in the gloves hygienic cotton gloves are to be put on prior to the pressure-tight gloves donning.

Регулятор давления скафандра с подсосом РДСП-3М-01 (Air Suction Suit Pressure Regulator)

The РДСП-3М-01 pressure regulator is designed for maintaining necessary absolute pressure in the spacesuit in case of the CA depressurization and for building up pressure differential during pressurization tests.

The regulator has two pressure modes (0.4 and 0.27 kgf/cm2) and its functions are:

The pressure regulator main parts are:

The bellows is the regulator sensitive element its operation principle being based on its elastic deformation /acting pressure relationship. The cover is the manual pressure adjustment aid.

The pressure regulator ensures one of the following conditions in the spacesuit depending on the cover position:

  1. When the cover is in the “0.4” position (i.e. at the medium stop):
    • if the CA pressure is normal the bellows is compressed and the valve is open forced by the undervalve spring and the suit interior volume is connected to the environmental atmosphere; there is a capability of breathing the outer air while the helmet is closed and there is no suit ventilation;
    • in case of the CA depressurization the bellows expanding gradually closes the valve at the level of P.CA=300 mm Hg and absolute pressure of 0.4 kgf/cm2 is maintained in the suit.
  2. When the cover is in the “Закрыто” (Closed) position (i.e. at the lower stop) the valve is closed forced by the over-valve spring and with the oxygen supply the pressure differential of 0.45 kgf/cm2 is maintained in the suit. This mode is used in the suit pressurization tests.
  3. When the cover is in the “0.27” position (i. e. at the upper stop) in case of the depressurized CA the bellows expands maximally and the load force acting on the valve is less than in the “0.4” cover position so the valve will close at a lower pressure level – at P.CA=200 mm Hg. And the absolute pressure of 0.27 kgf/cm2 is maintained in the suit. This mode is used when it is desirable to enhance the suit mobility for a short time period of no more than 5 minutes in the depressurized CA.

In order to transfer the regulator from the “0.4” to the “0.27” position it is necessary to pull the cover and screw it out till the upper stop.

In order to transfer the regulator from the “0.27” to the “0.4” position it is necessary to screw the cover in till the medium stop, pull it, pass the stop and then screw the cover out till that stop.

In order to close the pressure regulator it is necessary to screw the cover in from the medium stop to the lower stop then pull the cover and make sure it is screwed in home. The reverse operation is accomplished by screwing the cover out till the medium stop.

While the suit usage in flight is nominal the pressure regulator cover is to be in the “0.4” position except for presuurization test periods.

Указатель избыточного давления (УДиС-К) манометрического типа (Pressure Differential Manometric Indicator)

The УДиС-К pressure differential manometric indicator is designed for visual monitoring of the spacesuit pressure differential:


The indicator is implemented as a manometric capsule, its interior volume being connected to the space suit interior. The indicator principle of operation is based on the relationship between the pressure differential value and the elastic deformations of the manometric capsule – the indicator sensitive element which when deformed converts the pressure differential value into the capsule upper center linear displacement. This displacement is transmitted by the transfer/multiplying mechanism to the indicator pointer.

The indicator scale is graduated from 0 up to 0.45 kgf/cm2, the graduation marks being spaced at 0.02 kgf/cm2.

Spacesuit electric equipment

The electric equipment is designed to provide for the crew member radio communication (X3 umbilical) and medical monitoring (Ш9) with the spacesuit donned.

It consists of the pressure-tight electric lead through fixed to the suit shell, interior and exterior conductor bunches for the headset and medical harness connections to the spacecraft onboard systems.

Maintenance kit

The maintenance kit is designed for the spacesuit flight maintenance as its nominal usage procedure. The kit is located in the БО Module, fixed to the wall near the “сервант”.

Operation with the spacesuit

The “Sokol-KB-2” is a ventilation-type spacesuit.

While in nominal flight normal life support conditions in the suit are maintained by its venting with the cabin air. The air is fed to the suit by the onboard ventilation unit from the CA atmosphere at the flow rate of 180-200 nl per minute, that being sufficient for removing excess heat, breathing wastes and moisture from the suit. The coming air is fed through the elastic piping to the helmet, to the sleeves and to the feet by three approximately equal flows. The air goes out of the suit via the open helmet or via the pressure regulator when the helmet is closed.

In case of the CA depressurization life support conditions are ensured by constantly supplying oxygen into the suit from the stowage tanks. When the pressure in the CA falls down to 400 mm Hg the ventilation air supply to the suit is terminated and the constant oxygen supply is initiated. The suit ventilation manifold is isolated from the CA atmosphere (in the БР-1) and oxygen is pumped into the helmet. The oxygen flow rate of 20-23.5 nl per minute is enough for the breathing wastes and moisture removal from the helmet. When the CA pressure falls down to 300 mm Hg the pressure regulator closes maintaining absolute presure in the suit at 0.4 kgf/cm2 level. The pressure regulator also provides for the excess oxygen outlet from the suit.