Story of E-6B & Philip Dalton

E-6B, a well known name of slide graphic flight computer. All pilot students love it but also hate it, as it is one of the must-to-have tool help us to pass the FAA exam, but it is really not an easy work learn to use it correctly. Now the year is 2021, all types aircraft in flying school already updated with the newest & modern instrument such as Garmin G1000, so why we still need use this old item, which should be sent to the museum long time ago ?

A Must-to-Have tool for FAA exam

Before using E-6B flight computer, there was also another type ruler being used frequently for calculation purpose, we call it the Slide Rule. During the time without electronic computers, almost all scientific calculations, including high-order logarithms, exponents, trigonometric functions, and square roots, as well as calculations for the trajectory and point of impact of artillery shells in war, were all done using slide rules.

In the movie ‘’Apolo 13’’, we can also see the scene scientists are using slide rule busy calculating data for changing the orbit around the moon.

For flight training, actually there is no strict requirement for high accuracy data, but the pilots need the answer quickly and correct when using the slide rule for some kind of basic calculations. So there were many types flight computers were invented in the history, and the most famous one is the E-6B flight computer in year of 1940 during war II.

Nowadays, it is still a basic skill for every student in flying school. What seems funny is we can always see the students are holding the iPad in one hand, while using the E-6B in another hand; One is young and modern, one seems old and traditional. For most pilot students, it is difficult and time-consuming to learn how to use the E-6B in a good way, so the instructors also recommend electronic flight computers as alternative choice, it is much easier to use although surely it is more expensive, roughly $100 per unit for the electronic one.

Philip Dalton’s Genius Design

Philip Dalton

Philip Dalton, the inventor of E-6B. He was born in year 1903, this is a special year for aviation as this is the same year the Wright brothers’ “Aviator One” flew for the first time, achieving the first time in human history that operating aircraft with power which is heavier than air. His father was employed by General Electric, and he graduated from Cornell University with his eldest brother. During World War I, the eldest brother participated in the Army Aviation. He was also affected and joined the field artillery reserve training. Due to his long-term interest in physics and the need for artillery reserve training, Dalton began to think about how to manipulate artillery faster and more accurately. Aim at the target.

Navy Pilot Soldier using the navigation map

After the war, he received a master’s degree in physics from Princeton University in 1925, and was employed at Harvard University the following year to pursue a doctorate degree. Later, he joined the Naval Aviation (the US Air Force was not established until after World War II) to learn to fly, and in 1931 he began to be stationed in the reconnaissance detachment of the cruiser North Cape Town.

The experience on the cruiser reconnaissance unit had the most impact on him. During training, the instructor told him to control the joystick of the aircraft with one hand and a pencil in the other. This became the most important design concept of the E-6B slide rule later (time). Today, we still do this during flight training). At that time, the method of navigation was called “pilotage”, which was to fly to the destination based on the landmarks drawn on the aeronautical chart, such as flying along roads, railways, high-voltage power lines, or terrain. This navigation method is very difficult to identify landmarks in fine weather, not to mention bad weather. The bigger question is that Dalton was stationed on a cruiser, how can he navigate the vast sea without landmarks?

This requires the use of a navigation method called “Dead reckoning” (dead reckoning), which was used in early navigation and was borrowed from aviation. Dead reckoning method is to infer one’s position based on the position, direction and time of the last navigation point that is known from the distance. At that time, the dead reckoning method used by aviation had extremely large errors. In addition to wind deviation caused by wind, there were also vacuum speed errors caused by altitude and temperature errors. Although radio directional instruments have been used on a large scale at that time, for the pilots/navigators of reconnaissance aircraft, the enemy fleet must be detected to keep the radio silent, so the navigation of the cruiser landing can only rely on dead-reckoning.

Dalton initially invented the Mark VII, which looks similar like the E-6B, it is small and lightweight, and also with function for altimeter correction.

Mark VII in Smithsonian National Air and Space Museum

Dalton improved on the basis of Mark VII and invented the C-type wind triangle slide rule widely used in the Allied Forces of World War II and various improved versions, such as D-type and G-type. Dalton applied for his design. The patent was approved in 1938.

Dalton’s Plotting and Computing Device patent files
Mark G in Smithsonian National Air and Space Museum

Years later, the U.S. Army signed contract with Dalton and his partner Philip van Horn Weems, Dalton modified design per the Army’s requirement and then they created the famous E-6B flight computer. The Army Aviation began to use E-6B formally in 1940, but before that, the army stationed at Pearl Harbor in Hawaii had already purchased a lot. During the entire war, more than 400,000 E-6Bs were produced!

Initial Design of E-6B

Maybe it was the jealous talent. At 1 o’clock noon on July 24, 1941, Philip Dalton and cadet Harry Lee Rogers were conducting flight training. The plane went into a spiral, failed to escape and crashed. Both were killed in the accident. Philip Dalton was only 38 years old. At the time of his death, E-6B had been widely used in the aviation of the United States Army and Navy and the pilots of the Royal Air Force. At the same time, student pilots/navigators in various military forces were learning to use E-6B.

E-6B in Smithsonian National Air and Space Museum
E-6B in TAIWAN Museum
CHINA H-4 Air Navigation Device

What’s the secret that E-6B can be popular for 80 years? Why do pilots still use E-6B when technology is so advanced today?

We are finding the answers here.

The first reason is that aviation always has Plan B. The most classic example is the magnetic compass. Now all airplanes require a magnetic compass. No matter how advanced the navigation equipment is, the magnetic compass needs be prepared. This is for preventing reliable backup navigation equipment from being available when the navigation equipment fails or the electrical appliance fails. There are already expensive and advanced avionics calculators, with more functions and more practical, more user-friendly and easy-to-use interfaces, and “glass cockpits” like G1000. All I need is a glance. You can know. However, we still need E-6B because it does not require electricity and has sufficient functions to provide backup or cross-check when the electronic calculator fails or the results cannot be verified. An veteran pilot who has worked in civil aviation for decades in the aviation school said that he would still put an E-6B in his flight bag. Keep it in your bag and feel safely.

The second reason is that compared to electronic calculators, E-6B allows pilots to maintain control of the aircraft in one hand and use E-6B to calculate with the other hand. No matter how advanced or expensive electronic calculators are, no manufacturer dares to claim that they have achieved one-handed operation while maintaining flight control! In addition, although the E-6B cannot provide the accuracy comparable to that of an electronic computer, the results are often more intuitive (especially the wind drift angle). As long as one value is correct, the rest of the turntable is kept stationary, which is equivalent to directly looking up the meter, but rather than calculating. The keyboard repeatedly presses the keys quickly.

E-6B has become a symbol of aviation culture

Many antiques should be well preserved in aviation-themed museums, ranging from airplanes to small screw fasteners. This is the evidence left to future generations to prove that they once existed and served the world well; they can also be used in us When looking back, I sighed that the road we have traveled and the changes we have experienced have guided us to better develop and create the future!

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