Altitude Chambers
Altitude chambers, or hypobaric chambers, are environmental test chambers which simulate the type of low-pressure and low-oxygen environments found at high altitudes for product testing and human personnel training. Used by the U.S. Air Force beginning in the late 1940's, altitude chambers are commonly used to train jet and fighter plane pilots to withstand the low-oxygen environments they will face during high-altitude flights. These types of altitude chambers are walk-in test chambers large enough to fit from two to five people and are equipped with windows through which supervisory personnel may observe. The effects of low-pressure, low-oxygen high-altitude environments are called hypoxia, a condition which slows brain functioning, causing slow thought processes, lack of coordination and, if a person is subjected to hypoxia long enough, unconsciousness. For this reason, military personnel and occasionally civilian athletes undergo "altitude camp" in altitude chambers.
Aside from use in human training, smaller altitude chambers are used to test the viability, reliability and weakness of parts and electronic systems which may be exposed to high altitude environments during their product life. Critical military and aerospace components are tested in altitude chambers to ensure proper functioning under extreme low-pressure environments. Aircraft components, missile systems, helicopters, communication systems and commercial aircraft components must perform reliably in extreme altitudes; the failure of a missile guidance system, an aircraft radio or a helicopter rotor would likely result in a severe and fatal accident. Altitude testing reveals flaws and equipment failure in non-critical environments in order to avoid such disasters. Commercial parts which must be shipped via air are also tested in altitude chambers to ensure that no product damage will occur during shipping. Many automotive parts also require altitude testing to ensure that vehicles will remain fully functional in high-altitude mountainous terrains.
Altitude chamber manufacturers fabricate chambers which test for conditions of up to 100,000 feet above sea level, and temperature and humidity conditions are often included. Chambers designed for such extreme altitude testing must be equipped with heavy gauge walls to prevent the internal collapse of the structure due to the inside chamber's vacuum-like atmosphere. Less extreme chambers, such as those designed for human training (which reach a maximum altitude simulation of 25,000 feet), may be constructed with thinner sealed walls such as acrylic softwalls. Models for altitude testing vary greatly in size, from 12 square inch tabletop chambers to models twenty feet wide by forty feet long by sixteen feet high.