E6B

Manual E6-Bs/CRP-1s remain popular with some users and in some environments rather than the electronic ones because they are lighter, smaller, less prone to break, easy to use one-handed, quicker and do not require electrical power.

The graphic nature of the flight computer also helps in catching many errors which in part explains their continued popularity.

Just like on the flight computer, the ring is aligned with the air temperature and the pressure altitude, allowing the true airspeed (TAS) to be read at the needle.

The front side of the flight computer is a logarithmic slide rule that performs multiplication and division.

Throughout the wheel, unit names are marked (such as gallons, miles, kilometers, pounds, minutes, seconds, etc.)

The ruler then is slid so that the pencil mark is aligned with the true airspeed (B) seen through the transparent part of the wheel.

is approximated as 355/113 or 22/7) Wind Correction Angle: True ground speed: Wind Correction Angle, in degrees, as it might be programmed into a computer (which includes conversion of degrees to radians and back): True ground speed is calculated as: Although digital E6-Bs are faster to learn initially, many flight schools still require their students to learn on mechanical E6-Bs,[4] and for FAA pilot written exams and checkrides pilots are encouraged to bring their mechanical E6-Bs with them for necessary calculations.

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.

Dalton's first popular computer was his 1933 Model B, the circular slide rule with true airspeed (TAS) and altitude corrections pilots know so well.

In 1936 he put a double-drift diagram on its reverse to create what the U.S. Army Air Corps (USAAC) designated as the E-1, E-1A and E-1B.

A couple of years later he invented the Mark VII, again using his Model B slide rule as a focal point.

Dalton felt that it was a rushed design, and wanted to create something more accurate, easier to use, and able to handle higher flight speeds.

So he came up with his now famous wind arc slide, but printed on an endless cloth belt moved inside a square box by a knob.

This was for the Model C, D and G computers widely used in World War II by the British Commonwealth (as the "Dalton Dead Reckoning Computer"), the U.S. Navy, copied by the Japanese, and improved on by the Germans, through Siegfried Knemeyer's invention of the disc-type Dreieckrechner device, somewhat similar to the eventual E6-B's backside compass rose dial in general appearance, but having the compass rose on the front instead for real-time calculations of the wind triangle at any time while in flight.

Over 400,000 E-6Bs were manufactured during World War II, mostly of a plastic that glows under black light (cockpits were illuminated this way at night).

Many just called it the "Dalton Dead Reckoning Computer", one of its original markings.After Dalton's death, Weems[5] 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).