At first, fliers coped by filling tanks with pressurized oxygen and inhaling the gas through rubber tubes; later, form-fitting face masks made oxygen delivery more reliable. In many high-flying light airplanes and military aircraft, oxygen systems and face masks are still used to keep the pilot alive and conscious.
In , the U. Army Air Corps began research flights in a modified Lockheed Electra; the XC was the first airplane built with a pressurized cabin. The fuselage was designed with a circular cross-section to eliminate stress points when the fuselage expanded under pressure.
Openings were sealed to prevent air from escaping. Windows were reduced in size and strengthened, and the cabin inside became a pressure capsule—like a big aluminum can—that held five people.
Two years later, Boeing submitted a design to the Air Corps for a long-range bomber, the B Superfortress, which would have pressurized compartments for the crew.
Today all airliners are pressurized, and although the details vary among them, the basic elements of cabin pressurization systems are almost universal.
Air is pressurized by the engines. Turbofan engines compress intake air with a series of vaned rotors right behind the fan. At each stage of compression, the air gets hotter, and at the point where the heat and pressure are highest, some air is diverted. Some of the hot, high-pressure air, called bleed air , is sent to de-ice wings and other surfaces, some goes to systems operated by air pressure, and some starts its journey to the cabin.
The cabin-bound air has to be cooled first in an intercooler , a device like a car radiator that sheds the heat to the ambient air scooped aboard for that purpose. The air packs compress the incoming air to heat it before sending it to another intercooler to dump the heat to the outside. The air then expands through an expansion turbine, which cools it the way blowing with your lips pursed results in a cool flow of air.
By pressurizing the cabin, however, it creates a suitable environment with more oxygen, which is essential for our health and wellness. The use a pressurized cabin is essential for creating a safe environment for passengers, but it does carry the risk of a blowout. If a window breaks or emergency door opens, everything will be sucked out as the pressure attempts to equalize. The highly pressurized air inside the cabin will travel outside of the airplane where the pressure is much lower.
In many cases, the entire fuselage is pressurized, including the cargo hold. This means all checked luggage and other cargo the plane is carrying is under the same pressure. To recap, airplanes are pressurized because it protects pilot, crew and passengers from hypoxia. Airplanes are designed to pump air into the cabin to mimic the Hoses are commonly used in both automobiles and airplanes. Consisting of rubber tubes, they are We use cookies to improve your experience.
The cabin pressure is maintained constant with the help of a pressure regulator. The cabin pressure regulator controls the opening and closing of an aircraft's outflow valve, and — in turn — its proper operation is controlled by computers installed onboard the aircraft. An excellent example is that of the Honeywell cabin pressure control systems. These provide clear advantages such as thrust recovery outflow valve systems.
They optimize cabin air exhaust speed for improved fuel efficiency, single or multiple outflow systems to aid in cabin comfort and ventilation of heat and odors, and pneumatic safety valves for simple control and backup positive and negative pressure relief functionality. With innovations like the latest-generation digital cabin pressure control system, Honeywell continues its long legacy of pressure control system leadership that dates back more than 75 years — a heritage from names like Garrett, AiResearch and NormalAir.
This part of the cabin air system filters out contaminants, such as engine exhaust or deicing fluid, that may get into the bleed air. Most planes flying today use a cabin pressure control system that ensures safe and normal breathing for everyone onboard during flight.
The general rule is that planes should have cabin pressurization when they go above 10, to 14, feet. Most aircraft cabins are pressurized to an altitude of 8, feet, called cabin altitude.
Aircraft pilots have access to the mode controls of a cabin pressure control system and — if needed — can command the cabin to depressurize.
Should that happen, masks in the cabin become available to everyone onboard so that passengers and crew can breathe normally until the aircraft reaches a safe altitude lower than 10, feet. At cruising altitude, the cabin pressure is between approximately 11 and 12 pounds per square inch PSI , simulating the pressure we'd experience on a mountain that is between 6, to 8, feet high.
Reduced cabin pressure can have a series of effects on your body. During a long-haul flight you can get sleepy, have swollen feet, or can experience dry skin and dehydration due to the dry air source at the engine inlet. Rapid shifts in air pressure can make your ears pop.
Or you can experience none of the above and feel just fine. In the unlikely event of a loss of cabin pressure, oxygen masks become available for everyone onboard to help them breathe normally until the aircraft reaches a lower altitude and cabin pressure is restored.
Air supplied to an aircraft cabin — also known as conditioned air — is the main source of air for cabin pressurization on planes flying today. Bleed air is the source for conditioned air. This is air that goes through the plane's engine compressors and then into the cabin. The main components of a cabin pressurization system are the cabin pressure controller, pressure sensor, the outflow valve and the pressure relief valve.
The pressure controller, as one of its inputs, utilizes the pressure sensor information to measure the actual cabin pressure and cabin pressure rate of change.
Then, the cabin pressure controller controls the opening and closing of the outflow valve. Sign up to receive exclusive communications about offerings, events, news, surveys, special offers and related topics via telephone, email and other forms of electronic communication. During this time, the website will be intermittently available. We apologize in advance for any inconvenience. Popular Topics. How do I register for MyAerospace? How do I update my profile?
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