The E6B Flight Computer, so called “whiz wheel”, is mostly used in flight training but is still carried by professional and airline pilots. Flight planning counts on these flight computers to aid in calculating many items such as fuel burn, time en route, wind correction, ground speed…They are made out of cardboard and plastic or aluminum and plastic with printed or engraved lettering and markings. Metal models are inevitably more expensive than cardboard ones but not always more durable. Electronic versions of flight computer are also produces but manual E6Bs/CRP-1s are much more popular being lighter, smaller, easier to use one handed, quicker and not requiring electrical power.
Flight Computer History
The device’s original name is E-6B, often abbreviated as E6B, and was developed in the USA by Naval lt. Philip Dalton in the late 1930s. Philip Dalton was a Cornell University graduate who became a Naval Reserve pilot whose life ended in a plane crash. He was the one who invented, patented (with P. V. H. Weems) and marketed a series of flight computers.
His first popular computer was his 1933 Model B having True Airspeed (TAS) and Altitude corrections. A few years later he invented the Mark VII, using his Model B as a focal point. His Model C, D and G flight computers were widely used in World War II by Great Britain, the U.S. Navy and even by Japan and Germany. Wanting to create something more accurate and able to handle higher flight speeds, he came up with his now famous wind arc slide, printed on an endless cloth belt moved inside a square box by a knob. They cost too much to manufacture, so later he made a few changes making a protype called the Model H. In 1938 the Army wrote formal specifications, and had him make a few changes, which Weems called the Model J. The changes included moving the “10” mark to the top instead of the original “60”. This “E-6B” was introduced to the Army in 1940. And over 400,000 E-6Bs were manufactured during World War II, mostly of plastic.
The base name “E-6”was fairly arbitrary. Most likely they chose E because previously combined time and wind computer had been the E-1. The B simply stood for the production model.
Navigators and most instruction manuals continued using the original E-6B name, though the Army and Navy changed the marking to their joint standard, the AN-C-74 (Army/Navy computer 74). Later it was changed to AN-5835 and then to AN-5834 (1948).
After Dalton’s death, Weems tried calling the flight computer, the E-6C, E-10 and so on, but went back to the original name which was so well known. After the patent ran out, many manufacturers made copies, sometimes using a marketing name of “E6-B” (note the moved hyphen). An aluminium version was made by the London Name Plate Mfg. Co. Ltd. of London and Brighton and was marked “Computer Dead Reckoning Mk. 4A Ref. No. 6B/2645” followed by the arrowhead of UK military store.
Flight Computer in Pop Culture
2) “My eyes are dim I cannot see, I have not got my E-6B with me, over the Valley of the Ruhr”. (World War II USAAC ditty)
3) “His computer is the instrument on which he stakes his life … Don’t ask for his computer, for he’d sooner lend his wife”. (Navigator’s Song, 1943)
Printable E6-B Flight Computer
…or at least the front side of it! We found it on ben.com, be sure to check it out!
The first page assumes letter size and squeezes 2 sets of discs onto one page. Copy this onto card stock and cut carefully to assemble your own. On the next two pages it attempts to print each disc individually centered and at the largest possible size. You could use this to make a giant demo E6-B with a suitable printer. In that case you may want to edit the file and delete the stanza that prints the first page (near the end).
Ground School: Flight Computer Practice
Glossary of terms
The speed of an aircraft relative to the air.
Indicated airspeed corrected for pitot-static instal-lation and instrument errors.
The uncorrected reading obtained from the airspeed indicator.
Calibrated airspeed corrected for density altitude (pressure and temperature).
The height of an aircraft above mean sea level or above the terrain.
True altitude corrected for terrain elevation; the vertical distance of the aircraft above the terrain.
Indicated pressure altitude corrected for instru¬ment error. Also known as flight-level pressure altitude,
Calibrated altitude corrected for temperature; the vertical distance of the aircraft above the standard datum plane.
PRESSURE ALTITUDE (PA).
The reading of the pressure altimeter with the baro-metric window set at 29.92.
The density altitude corrected for pressure alti¬tude variation (PAV); the vertical distance above mean sea level.
The direction of the intended path of the aircraft over the earth; or the direction of a line on a chart representing the intended aircraft pathr ex¬pressed as the angle measured from a specific refer¬ence datum clockwise from 0° through 360° to the line.
The course of an aircraft measured with reference to the north magnetic pole.
The course of an aircraft measured with reference to the true north, or geographic, pole. (The true course is always represented by the centerline of the flight computer grid.)
The speed of the aircraft relative to the ground. (Ground speed is always represented by the center of the azimuth of the flight computer.)
The angular direction of the longitudinal axis of an aircraft measured clockwise from a reference point.
The reading taken directly from the compass.
The heading of an aircraft with reference to magnetic north.
The heading of an aircraft with reference to grid north.
The speed of a moving object compared to the speed of sound within the same medium of movement. A speed of Mach 2.5 would be two and one-half times the speed of sound in the same medium.
NAUTICAL MILE (NM).
A unit of distance used in navigation, 6080 feet; the mean length of one minute of longitude on the equator; approximately 1 minute of latitude; 1.15 statute miles.
STATUTE MILE (SM).
5,280 feet or .827 nautical miles.
WIND CORRECTION ANGLE.
The number of degrees that the aircraft longitudinal axis must be dis¬placed, to the right or left of the true course and the true heading. (The wind correction angle is always displayed on the computer between the centerline of the grid and the wind dot.)