The E6B is a form of circular slide rule used in aviation. The name is variously spelled as E6B, E-6B, E6-B, and even (rarely) E-6-B. They are mostly used in flight training, but many professional and even airline pilots will still carry and use their E6Bs. E6Bs are used during flight planning (on the ground before takeoff) to aid in calculating fuel burn, wind correction, time enroute, and other items. In the air, the E6B can be used to calculate ground speed as well. The back is designed for wind correction calculations, ie determining how much the wind is affecting your speed and course.
Construction
They are usually made out of aluminum and plastic, with lettering and markings engraved into the metal. Some are made out of cardboard and plastic, usally for students. Otherwise identical, these are less expensive but also far less durable.
Electronic versions are also produced, resembling calculators rather than manual slide rules. Aviation remains one of the few places that the slide rule still is in widespread use, where the manual version is far more popular than the electronic ones.
In addition, computer programs to emulate E6B functions are also available, both for desktop computers and Palm Pilot-type portables, of which the latter can be used in the cockpit just as easily.
History
The current E6B was developed in the United States sometime in the 1930s, although various online sources say it was invented in the United Kingdom a decade or so earlier. The name seems to come from the U.S Army Air Force in World War Two. The first E6Bs were made of brass; aluminum & plastic designs were also produced during WW2.
External links:
International Slide Rule Group on Yahoo!