Retrotechtacular: Fire Control Computers in Navy Ships

Here is a two-part Navy training film from 1953 that describes the inner workings of mechanical fire control computers. It covers seven mechanisms: shafts, gears, cams, differentials, component solvers, integrators, and multipliers, and does so in the well-executed fashion typical of the era.

Fire control systems depend on many factors that occur simultaneously, not the least of which are own ship’s speed and course, distance to a target, bearing, the target’s speed and course if not stationary, initial shell velocity, and wind speed and direction.

The mechanisms are introduced with a rack and pinion demonstration in two dimensions. Principally speaking, a shaft carries a value based on revolutions. From this, a system can be geared at different ratios.

Cams take this idea further, transferring a regular motion such as rotation to an irregular motion. They do so using a working surface as input and a follower as output. We are shown how cams change rotary motion to linear motion. While the simplest example is limited to a single revolution, additional revolutions can be obtained by extending the working surface. This is usually done with a ball in a groove.

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Retrotechtacular: Blue Collar, Red Nightmare

This week’s presentation is a well-cast piece of anti-Communist propaganda perpetrated by a division of the DoD that you’ve probably never heard of: the Directorate for Armed Forces Information and Education.

It’s narrated by Jack Webb of Dragnet and Adam-12 fame. He tells us of a fake American town located somewhere behind the Iron Curtain. It’s full of young comrades who sock hop and bebop while studying and playacting the bourgeoisie activities of the American economy and way of life. After introducing this, Webb pulls back the cushy, velvet curtain to profile a typical American household led by one [Jerry Donavan].

[Jerry] has it all: a wise-cracking wife played by Jeanne Cooper (most notably of The Young and the Restless), a son with a healthy interest in war games, a young daughter with pretty blond hair, and a beautiful older daughter who would go on to fame up the road at Petticoat Junction. After some unsettling news from this daughter at the dinner table, Jerry heads up to bed early to catch a few Zs.

Jack Webb denies [Jerry] any visions of sugar plums and instead drops him in the middle of Fakesville, USSR for a vivid nightmare of an America reconstructed by Communism. Watch as he figures out what’s going on and what the new regime means for him and his good-looking family.

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Retrotechtacular: Core Competencies

As the dashing officer shown above will tell you, early data processing machines and ADP systems employed two types of magnetic cores for memory and other purposes. This 1961 U.S. Army training film is an introduction to the properties of ferrite cores, which are commonly made from nickel alloy and other magnetic materials. As this is only part one of a series, the metallic ribbon type of magnetic core is covered in some other segment we have yet to locate.

The use of magnetic cores for random access memory was built upon transformer theory and provided a rugged and low-power solution until the semiconductor came into vogue. Before that time, the humble ferrite core served many uses and did so very well. The Apollo Guidance Computer had erasable magnetic core memory, and much of its software was stored in core rope memory.

binary 1The film covers a lot of theory and does so clearly and concisely. It begins by explaining what a magnetic core is and why it’s used, and then moves on to describe how the cores are used to store bits and the method by which they can transfer information to other cores. Along the way, it provides background on bi-stable devices and provides explanation of magnetization behavior in terms of magnetizing force and flux density.

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Retrotechtacular: The Future’s So Bright, We’re Gonna Need Photochromic Windowpanes

This is a day in the life of the Shaw family in the summer of 1999 as the Philco-Ford Corporation imagined it from the space-age optimism of 1967. It begins with Karen Shaw and her son, James. They’re at the beach, building a sand castle model of their modular, hexagonal house and discussing life. Ominous music plays as they return in flowing caftans to their car, a Ford Seatte-ite XXI with its doors carelessly left open. You might recognize Karen as Marj Dusay, who would later beam aboard the USS Enterprise and remove Spock’s brain.

The father, Mike Shaw, is an astrophysicist working to colonize Mars and to breed giant, hardy peaches in his spare time. He’s played by iconic American game show host Wink Martindale. Oddly enough, Wink’s first gig was hosting a Memphis-based children’s show called Mars Patrol. He went on to fame with classics such as Tic Tac Dough, Card Sharks, Password Plus, and Trivial Pursuit.

Mike calls up some pictures of the parent trees he’s using on a screen that’s connected to the family computer. While many of today’s families have such a device, this beast is almost sentient. We learn throughout the film that it micromanages the family within an inch of their lives by keeping tabs on their physiology, activities, financial matters, and in James’ case, education.

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Retrotechtacular: The First Atlas Launch

As the Cold War conflict expanded in the 1950s, the Soviet Union dry-tested a hydrogen bomb and defense tactics became a top priority for the United States. Seeking to create a long-range nuclear missile option, the Air Force contracted Convair Astronautics to deliver SM-65 Atlas, the first in series of ICBMs. In the spotlight this week is a sort of video progress report which shows the first launch from Cape Canaveral’s LC-14 on June 11, 1957.

After the angle of attack probe is unsheathed, everyone moves out of the way. The launch is being monitored by base central control, but the swingin’ spot to spectate is the blockhouse. They have a periscope and everything. As the countdown continues, liquid oxygen pipelines whistle and wail into the idyllic Florida afternoon with the urgency of a thousand teakettles. Cameras and tracking equipment are readied, and the blockhouse’s blast door is sealed up tight.

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Retrotechtacular: The Diesel Story

The diesel engine was, like many things, born of necessity. The main engine types of the day—hot bulb oil, steam, coal gas, and gasoline—were not so thermally efficient or ideal for doing heavy-duty work like driving large-scale electrical generators.  But how did the diesel engine come about? Settle in and watch the 1952 documentary “The Diesel Story“, produced by Shell Oil.

The diesel engine is founded on the principle of internal combustion. Throughout the Industrial Age, technology was developing at breakneck pace. While steam power was a great boon to many burgeoning industries, engineers wanted to get away from using boilers. The atmospheric gas engine fit the bill, but it simply wasn’t powerful enough to replace the steam engine.

hot bulb oil engineBy 1877, [Nikolaus Otto] had completed work on his coal gas engine built on four-stroke theory. This was the first really useful internal combustion engine and the precursor of modern four-stroke engines. It was eventually adapted for transportation with gasoline fuel. In 1890, the hot bulb oil engine was developed under the name Hornsby-Akroyd and primarily used in stationary power plants. Their flywheels had to be started manually, but once the engine was going, the bulb that drove combustion required no further heating.

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Retrotechtacular: The CURTA Mechanical Calculator

The CURTA mechanical calculator literally saved its inventor’s life. [Curt Herzstark] had been working on the calculator in the 1930s until the Nazis forced him to focus on building other tools for the German army. He was taken by the Nazis in 1943 and ended up in Buchenwald concentration camp. There, he told the officers about his plans for the CURTA. They were impressed and interested enough to let him continue work on it so they could present it as a gift to the Führer.

This four-banger pepper mill can also perform square root calculation with some finessing. To add two numbers together, each must be entered on the digit setting sliders and sent to the result counter around the top by moving the crank clockwise for one full rotation. Subtraction is as easy as pulling out the crank until the red indicator appears. The CURTA performs subtraction using nine’s complement arithmetic. Multiplication and division are possible through successive additions and subtractions and use of the powers of ten carriage, which is the top knurled portion.

Operation of the CURTA is based on [Gottfried Leibniz]’s stepped cylinder design. A cylinder with cogs of increasing lengths drives a toothed gear up and down a shaft. [Herzstark]’s design interleaves a normal set of cogs for addition with a nine’s complement set. When the crank is pulled out to reveal the red subtraction indicator, the drum is switching between the two sets.

Several helper mechanisms are in place to enhance the interface. The user is prevented from ever turning the crank counter-clockwise. The crank mechanism provides tactile feedback at the end of each full rotation. There is also a lock that disallows switching between addition and subtraction while turning the crank—switching is only possible with the crank in the home position. There is a turns counter on the top which can be set to increment or decrement.

You may recall seeing Hackaday alum [Jeremy Cook]’s 2012 post about the CURTA which we linked to. A great deal of information about the CURTA and a couple of different simulators are available at curta.org. Make the jump to see an in-depth demonstration of the inner workings of a CURTA Type I using the YACS CURTA simulator.

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