The E6B Flight Computer, or simply the “whiz wheel”, is a mechanical circular slide rule used in aviation.
They are mostly used in flight training, but many professional and even airline pilots still carry and use these flight computers. These flight computers are used during flight planning (on the ground before takeoff) to aid in calculating fuel burn, wind correction, time en route, and other items. In the air, the flight computer can be used to calculate ground speed as well. The back is designed for wind correction calculations, i.e., determining how much the wind is affecting one’s speed and course.
They are usually made out of cardboard and plastic, or aluminium and plastic, with printed lettering and markings, or engraved into the metal.
The E6-B has been around a long time. It was developed in the United States by Naval Lt. Philip Dalton in the late 1930s. The name comes from its original part number for the U.S Army Air Corps in World War II.
Philip Dalton was a Cornell University graduate who joined the United States Army as an artillery officer, but soon resigned and became a Naval Reserve pilot from 1931 until he died in a plane crash with a student practicing spins. He, with P.V.H. Weems, invented, patented and marketed a series of flight computers.
The base name “E-6” was fairly arbitrary, as there were no standards for stock numbering at the time. For example, other USAAC computers of that time were the C-2, D-2, D-4, E-1 and G-1, and flight pants became E-1s as well. Most likely they chose “E” because Dalton’s previously combined time and wind computer had been the E-1. The “B” simply meant it was the production model.
After Dalton’s death (1903–1941) , Weems updated the E-6B and tried calling it the E-6C, E-10, and so forth, but finally fell back on the original name, which was so well known by 50,000 World War II Army Air Force navigator veterans. After the patent ran out, many manufacturers made copies, sometimes using a marketing name of “E6-B” (note the moved hyphen).
Although digital E6Bs are faster to learn initially, many flight schools still require their students to learn on mechanical E6Bs and for FAA pilot written exams and check-rides pilots are encouraged to bring their mechanical E6Bs with them for necessary calculations.