Pressure suit
Encyclopedia
A pressure suit is a protective suit worn by high-altitude pilots who may fly at altitudes where the air pressure is too low for an unprotected person to survive, even breathing pure oxygen at positive pressure
Positive pressure
Positive pressure is a pressure within a system that is greater than the environment that surrounds that system. Consequently if there is any leak from the positively pressured system it will egress into the surrounding environment....

. Such suits may be either full-pressure (i.e. a space suit
Space suit
A space suit is a garment worn to keep an astronaut alive in the harsh environment of outer space. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extra-vehicular activity , work done outside spacecraft...

) or partial-pressure (as used by air crew). Partial-pressure suits work by providing mechanical counter-pressure to assist breathing at altitude.

Diving
Diving
Diving is the sport of jumping or falling into water from a platform or springboard, sometimes while performing acrobatics. Diving is an internationally-recognized sport that is part of the Olympic Games. In addition, unstructured and non-competitive diving is a recreational pastime.Diving is one...

 suits that protect the wearer from excessively high pressure are called atmospheric diving suit
Atmospheric diving suit
An atmospheric diving suit or ADS is a small one-man articulated submersible of anthropomorphic form which resembles a suit of armour, with elaborate pressure joints to allow articulation while maintaining an internal pressure of one atmosphere...

s. Pressure suits in general are examples of environmental suit
Environmental suit
An environmental suit is a suit designed specifically for a particular environment, usually one otherwise hostile to humans. An environment suit is typically a one-piece garment, and many types also feature a helmet or other covering for the head...

s.

Background

The region from sea level to around 10000 ft (3,048 m) is known as the physiological-efficient zone. Oxygen levels are usually high enough for humans to function without supplemental oxygen and decompression sickness
Decompression sickness
Decompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...

 is rare.

The physiological-deficient zone extends from 12000 ft (3,657.6 m) to about 50000 ft (15,240 m). There is an increased risk of problems such as hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...

, trapped-gas dysbarism
Dysbarism
Dysbarism refers to medical conditions resulting from changes in ambient pressure. Various activities are associated with pressure changes. Scuba diving is the most frequently cited example, but pressure changes also affect people who work in other pressurized environments , and people who move...

 (where gas trapped in the body expands), and evolved-gas dysbarism (where dissolved gases such as nitrogen may form in the tissues, i.e. decompression sickness
Decompression sickness
Decompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...

). Above approximately 34000 ft (10,363.2 m) oxygen-rich breathing mixture is required to approximate the oxygen available in the lower atmosphere, while above 40000 ft (12,192 m) oxygen must be under positive pressure. Generally, 100% oxygen is used to maintain an equivalent altitude of 10000 ft (3,048 m).

Partial pressure

Suits that only pressurize certain parts of the body, they can only provide protection up to a certain altitude. These do not provide protection for extended periods of time at low ambient pressure.

Full pressure

Suits that pressurize the entire body, these suits have no altitude limit. Extra-vehicular Activity spacesuits are always fully pressurized.

Exposure to space without a spacesuit

The human body can briefly survive the hard vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

 of space unprotected, despite contrary depictions in much popular science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

. Human flesh expands to about twice its size in such conditions, giving the visual effect of a body builder rather than an overfilled balloon. Consciousness is retained for up to 15 seconds as the effects of oxygen starvation
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...

 set in. No snap freeze effect occurs because all heat must be lost through thermal radiation
Thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....

 or the evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

 of liquids, and the blood does not boil because it remains pressurized within the body. The greatest danger is in attempting to hold one's breath before exposure, as the subsequent explosive decompression can damage the lungs. These effects have been confirmed through various accidents (including in very high altitude conditions, outer space and training vacuum chambers). Human skin does not need to be protected from vacuum and is gas-tight by itself. Instead it only needs to be mechanically compressed to retain its normal shape. This can be accomplished with a tight-fitting elastic body suit and a helmet for containing breathing gases, known as a space activity suit
Space activity suit
A space activity suit or mechanical counterpressure suit is an experimental spacesuit which applies stable pressure against the skin by means of skintight elastic garments. The SAS is not inflated like a conventional spacesuit: it uses mechanical pressure, rather than air pressure, to compress the...

.

Russia

In Russia, the first full pressure suit was designed by engineer Evgeniy Chertovsky in Leningrad
Leningrad
Leningrad is the former name of Saint Petersburg, Russia.Leningrad may also refer to:- Places :* Leningrad Oblast, a federal subject of Russia, around Saint Petersburg* Leningrad, Tajikistan, capital of Muminobod district in Khatlon Province...

 in 1931. The CH-1 was a simple pressure-tight suit with a helmet which did not have joints, thus requiring substantial force to move the arms and legs when pressurised. This was remedied in later suits. Work on full pressure suits was carried out during 1936-41 by the Central Aerohydrodynamic Institute
TsAGI
TsAGI is a transliteration of the Russian abbreviation for Центра́льный аэрогидродинами́ческий институ́т or "Tsentralniy Aerogidrodinamicheskiy Institut", the Central Aerohydrodynamic Institute....

 (TsAGI), with similar work being carried out by the Gromov Flight Research Institute
Gromov Flight Research Institute
M. M. Gromov Flight Research Institute or LII for short is an important Russian aircraft test base, scientific research center located in Zhukovsky, 40 km south-east of Moscow.It has one of the longest runways in Europe at 5,403 m...

 (LII) after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. The LII produced four experimental full pressure suits for aircrews, and in 1959 began work on full pressure suits for spaceflight. Chertanovskiy used the name skafander for full pressure suits, from the French scaphandre ("diving suit"); skafander has since become the term used by Russians to refer to standard diving dresses
Diving suit
A diving suit is a garment or device designed to protect a diver from the underwater environment. A diving suit typically also incorporates an air-supply .-History:...

 or space suits.

Haldane-Davis

In 1931, American Mark Ridge became obsessed with breaking the world altitude record in an open gondola balloon. Recognizing that the flight would require specialised protective clothing, he visited the UK in 1933 where he met with Scottish
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

 physiologist John Scott Haldane, who had published a concept for a fabric full pressure suit in the 1920s. The two sought the assistance of Robert Henry Davis
Robert Davis (inventor)
Sir Robert Henry Davis was an English inventor and director of the Siebe Gorman company. His main invention was the Davis Submerged Escape Apparatus, an oxygen rebreather that Davis patented for the first time in 1910, inspired by the rebreathers that Henry Fleuss patented as of 1876...

 of Siebe Gorman
Siebe Gorman
Siebe Gorman & Company Ltd was a British company which developed diving equipment and breathing equipment and worked on commercial diving and marine salvage projects...

, the inventor of the Davis Escape Set, and with Haldane's and Davis' resources a prototype suit was constructed. Ridge tested it in a low-pressure chamber to a simulated altitude of 50,000 feet. However, he received no support for further work and never made his attempt on the world record. On 28 September 1936 Squadron Leader
Squadron Leader
Squadron Leader is a commissioned rank in the Royal Air Force and the air forces of many countries which have historical British influence. It is also sometimes used as the English translation of an equivalent rank in countries which have a non-English air force-specific rank structure. In these...

 F.R.D. Swain of the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 set the official world altitude record at 49,967 feet in a Bristol Type 138 wearing a similar suit.

Wiley Post

In 1934, aviator Wiley Post
Wiley Post
Wiley Hardeman Post was a famed American aviator, the first pilot to fly solo around the world. Also known for his work in high altitude flying, Post helped develop one of the first pressure suits. His Lockheed Vega aircraft, the Winnie Mae, was on display at the National Air and Space Museum's...

, working with Russell S. Colley of the B.F. Goodrich Company, produced the world's first practical pressure suit. The suit's body had three layers: long underwear, a rubber air pressure bladder, and an outer suit of rubberized parachute fabric which was attached to a frame with arm and leg joints that allowed Post to operate aircraft controls and to walk to and from the aircraft. Attached to the frame were pigskin gloves, rubber boots, and an aluminum and plastic helmet with a removable faceplate that could accommodate earphones and a throat microphone. In the first flight using the suit on September 5, 1934, Post reached an altitude of 40,000 feet above Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

, and in later flights reached 50,000 feet.

World War II

In the US, a large amount of effort was put into the development of pressure suits during World War II. While B.F. Goodrich led the field, other companies involved in such research included the Arrowhead Rubber Co., Goodyear
Goodyear Tire and Rubber Company
The Goodyear Tire & Rubber Company was founded in 1898 by Frank Seiberling. Goodyear manufactures tires for automobiles, commercial trucks, light trucks, SUVs, race cars, airplanes, farm equipment and heavy earth-mover machinery....

, and US Rubber
United States Rubber Company
The United States Rubber Company was founded in Naugatuck, Connecticut in 1892. It was one of the original 12 stocks in the Dow Jones Industrial Average, and became Uniroyal Inc...

. The University of Minnesota
University of Minnesota
The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...

 worked with Bell Aircraft
Bell Aircraft
The Bell Aircraft Corporation was an aircraft manufacturer of the United States, a builder of several types of fighter aircraft for World War II but most famous for the Bell X-1, the first supersonic aircraft, and for the development and production of many important civilian and military helicopters...

 and the US National Bureau of Standards
National Institute of Standards and Technology
The National Institute of Standards and Technology , known between 1901 and 1988 as the National Bureau of Standards , is a measurement standards laboratory, otherwise known as a National Metrological Institute , which is a non-regulatory agency of the United States Department of Commerce...

. The Bureau of Standards and the University of California
University of California
The University of California is a public university system in the U.S. state of California. Under the California Master Plan for Higher Education, the University of California is a part of the state's three-tier public higher education system, which also includes the California State University...

 acted as clearing houses to distribute information to all the companies involved. No effective fully mobile pressure suits were produced in World War II but the effort provided a valuable basis for later development.

David Clark Company

Following the war, the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

 caused continued funding of aviation development, which included high altitude, high speed research such as NACA
NACA
- Organizations :* National Advisory Committee for Aeronautics, the forerunner of the U.S. federal agency NASA* National Association for Campus Activities, an organization for programmers of university and college activities...

's X-1
Bell X-1
The Bell X-1, originally designated XS-1, was a joint NACA-U.S. Army/US Air Force supersonic research project built by Bell Aircraft. Conceived in 1944 and designed and built over 1945, it eventually reached nearly 1,000 mph in 1948...

. James Henry of the University of Southern California
University of Southern California
The University of Southern California is a private, not-for-profit, nonsectarian, research university located in Los Angeles, California, United States. USC was founded in 1880, making it California's oldest private research university...

 devised a partial pressure suit using an oxygen mask
Oxygen mask
An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover the nose and mouth or the entire face...

 to provide pressurised oxygen, with gas pressure also inflating rubber tubes called capstans to tighten the suit and provide sufficient mechanical counterpressure to just balance the breathing pressure necessary to prevent hypoxia at a particular altitude. The David Clark Company
David Clark Company
David Clark Company, Inc. is an American manufacturer, best known for noise attenuating headsets with boom microphones for use in military aviation, commercial aviation, industry and professional communication in high-noise environments...

 supplied technical support and resources, and a prototype suit was tested to a simulated 90,000 feet at Wright Field
Wright Field
Wright Field was an airfield of the United States Army Air Corps and Air Forces near Riverside, Ohio. From 1927 to 1947 it was the research and development center for the Air Corps, and during World War II a flight test center....

 in 1946. Henry's design was subsequently developed by the David Clark Company into the S-1 and T-1 flight suit used by X-1 pilots. The X-1 was succeeded by the Douglas Skyrocket
Douglas Skyrocket
The Douglas D-558-2 Skyrocket was a rocket and jet-powered supersonic research aircraft built by the Douglas Aircraft Company for the United States Navy...

, whose objective was to exceed Mach 2, and an improved pressure suit was required. David Clark won the contract in 1951 with their first full pressure suit, the Model 4 Full Pressure Suit; it was first flown in 1953 by USMC aviator Marion E. Carl
Marion E. Carl
Major General Marion Eugene Carl, USMC, was a World War II fighter ace, record setting test pilot, and a notable naval aviator. He was the first Marine Corps ace in World War II.-Early years:...

 who became the first US military aviator to wear a full pressure suit, at the same time setting an unofficial worlds altitude record in the Skyrocket.

Goodrich Mk III & IV

US requirements for high-altitude reconnaissance aircraft such as the U-2
Lockheed U-2
The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency . It provides day and night, very high-altitude , all-weather intelligence gathering...

, and fighters to intercept high-altitude Soviet aircraft caused the US Navy to be tasked with the development of a full pressure suit in the 1950s. Working with B.F. Goodrich and Arrowhead Rubber, the USN produced a series of designs which culminated in the Goodrich Mk III and IV. While intended for aircraft use, the Mk IV was later used by NASA with modifications for Project Mercury
Project Mercury
In January 1960 NASA awarded Western Electric Company a contract for the Mercury tracking network. The value of the contract was over $33 million. Also in January, McDonnell delivered the first production-type Mercury spacecraft, less than a year after award of the formal contract. On February 12,...

 as the Navy Mark V
Navy Mark V
The Navy Mark IV high-altitude pressure suit was a full-body pressure suit originally developed by the B.F. Goodrich Company and the U.S. Navy for wear in high-altitude fighter aircraft operations...

. At the same time, David Clark won the contract to produce suits for the X-15 project; its XMC-2 suits qualified as the first US spacesuits.

RAF

The RAF Institute of Aviation Medicine
RAF Institute of Aviation Medicine
The Royal Air Force Institute of Aviation Medicine was a British Royal Air Force aviation medicine research unit between 1945 and 1994.- Early days :The RAF Institute of Aviation Medicine was opened on 30 April 1945 by the Princess Royal...

 and the Royal Aircraft Establishment
Royal Aircraft Establishment
The Royal Aircraft Establishment , was a British research establishment, known by several different names during its history, that eventually came under the aegis of the UK Ministry of Defence , before finally losing its identity in mergers with other institutions.The first site was at Farnborough...

 developed a partial-pressure helmet which was used with a capstan type suit purchased from the US. It was worn by Walter Gibb
Walter Gibb
Wing Commander Walter Gibb DSO, DFC was a flying ace and a British test pilot who twice held the world altitude record.- Early life :...

 and his navigator to set a world altitude record on 29 August 1955 in an English Electric Canberra
English Electric Canberra
The English Electric Canberra is a first-generation jet-powered light bomber manufactured in large numbers through the 1950s. The Canberra could fly at a higher altitude than any other bomber through the 1950s and set a world altitude record of 70,310 ft in 1957...

. However, evaluation of the suit showed that it encumbered the wearer and did not integrate well with RAF escape systems. Instead, the RAF IAM proposed a minimal-coverage suit which would provide "get-me-down" protection. The RAF never issued a partial-pressure suit, preferring instead to use anti-g trousers in conjunction with pressure jerkins (which applied mechanical counter-pressure to the wearer's chest).

External links

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