VINTAGE 1968 DALTON E-6B MARK I ‘DIAL-A-CON” FLIGHT COMPUTER CALCULATOR ~ LOOK!

Description

VINTAGE 1968 DALTON E-6B MARK I ‘DIAL-A-CON” FLIGHT COMPUTER CALCULATOR
This week on Ebay we are offering up this very cool old vintage hand-held flight calculator.
This one was made by the Felsenthal Instruments Company and is clearly dated “Pat. Pend. 1968” on the front plate. It’s a very cool piece of aviation history.
It is in very nice condition, all the dials and the WAC plate move smoothly and it appears to function just fine, despite it being over 50 years old.
This one comes with its original tan vinyl carrying case. The case is marked “Jeppesen ~ E68B-1P ~ Computer.”, although the wording is a little worn. The case is a little dirty and scuffed up. This little flight calculator has logged a lot of air miles. Both the calculator and the case could use a good cleaning, but it’s in great condition as is.
This vintage one is made of aluminum and durable plastic and comes in its little vinyl plastic case.
The Felsenthal Company was based in Chicago and made many early ‘celluloid specialties’ and plastic items, but during WWII, they produced many of the essential plastic aviation navigation instruments used by pilots. After the war, they went back to making various injection molded plastic items including auto parts, food containers, home appliances, and televisions. They also continued making Flight Computers for many years. This one was made by them in 1968.
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Flight Calculators, such as this beauty, typically had 2 faces; a calculator side and a wind side.
The WIND SIDE of the computer consists of a rotating azimuth and a rectangular grid that slides up and down through the azimuth. The sliding grid card usually has two sides, a low speed and a high speed side.
The azimuth circle rotates freely and is graduated into 360°. The transparent portion is frosted so that it can be written on and readings marked off with a pencil. This side helps calculate wind vectors, or how the wind is affecting one's speed, altitude and course.
It can be used for determining Ground Speed and True Heading, for finding Drift Angles (Off-Course), calculating True Altitude and Density Altitude, as well determining Unknown Wind, for Finding Altitude for Most Favorable Winds and for determining your Radius of Action.
A typical calculation performed on this side of the calculator is "If I want to fly on course A at a speed of B, but I encounter wind coming from direction C at a speed of D, then how many degrees must I adjust my heading, and what will my ground speed be?" That’s quite easy to figure out with this little tool.
The CALCULATOR SIDE of the computer consists of a special circular slide rule with various log scales for multiplication and division. The associated third scale is calibrated in hours and minutes.
This side is used to calculate Time and Distance, Fuel Consumption, True Airspeed, and to convert Mach Number to True Airspeed. This side can be used to calculate ground speed, estimate fuel use, and determine the time of arrival.
The ring on the front is aligned with the air temperature and the pressure altitude, allowing the true airspeed (TAS) to be read off easily at the pointer. Extra marks and windows facilitate calculations specifically needed in aviation and help with changing between Nautical Values and Statute Equivalents, and for converting between Statute equivalents to Kilometers. Throughout the wheel, unit names are marked (such as gallons, miles, kilometers, pounds, minutes, seconds, etc.) at locations that correspond to the fixed constants that are used when converting from one unit to another in various calculations.
Once the wheel is ‘set’ to a certain fixed ratio (for example, pounds of fuel per hour), the rest of the wheel can be used to utilize that same ratio in solving problems. (for example, how many pounds of fuel for a 3.5-hour flight?)
In case you forgot, the instructions for ratio calculations and wind problems are printed on either side of the computer for reference.
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A very handy powerful tool to have with you in the air. Plus the fact that it always works and is not dependent on the plane’s power or on batteries. An ingenious little tool. A potential life saver. These were used by every pilot back in the day, but are mostly used in flight training today. Modern avionics and electronics have made them somewhat obsolete, but they can still be used in an emergency and still work fine to give you accurate useful information. The simple graphic nature of the flight computer also helps in catching many errors, which in part explains their continued popularity.
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THE HISTORY OF THE E-6B FLIGHT CALCULATOR
The E-6B was developed in the United States by Naval Lt. Philip Dalton in the late 1930s.
In 1936 Dalton filed a patent for what he called a ‘Flight Computer’ used to calculate basic things such as True Air Speed, Altitude, altitude correction, fuel consumption and other essential information. Dalton was most famous for his ‘wind arc’ slide that could be used for higher flight speeds. Most flight calculators had a 2-sided WAC slide that could be flipped over for calculating wind drift at higher speeds.
By 1937, Dalton created a simple, flat wind drift slide, with his old Model B circular slide rule included on the front. He called this patent prototype his Model H; the Army called it the E-6A. The name comes from its original Army part number.
In 1938, it was modified slightly, moving the “10” mark to the top, as in this version, and making it more streamlined and flat. This became the E-6B. Dalton introduced it to the Army in 1940, shortly before Pearl Harbor. The E6-B became known as "Dalton's Dead Reckoning Computer" and was used in WWII by the allies and even copied by the Japanese and Germans.
Over 400,000 E-6Bs were made during World War II, mostly of a plastic that glows under a black light, which was the way cockpits were illuminated at night back then.
By 1943, the army renamed the E-6B the ‘AN-C-74’ for Army Navy Computer #74, but most every pilot called it the E-6B or the "Dalton Dead Reckoning Computer."
Dalton died in a crash training pilots, but his flight calculator lived on. Once his original patent ran out, many forms of the E6-B were made with all sorts of different names, but they were all basically the same and haven’t changed much to this day. This 1968 model is basically a fancier E-6B.
They were used by military and commercial airlines for years until modern aviation electronics made them somewhat obsolete. An updated version of the E6-B is still used today to teach basic piloting classes and to teach the fundamental computations needed to fly. Some private pilots still prefer to use them for their navigation because they are light, small, less prone to breaking or malfunctioning, easy to use one-handed, quick, and do not require electrical power.
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A very cool, old Felsenthal Flight Computer from 1968 in excellent condition. A cool item to have in your man-cave, or fun to have to stump your friends. These are interesting, fun and still highly collectible.
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