Sunday, February 23, 2020

Ancient Computers

Perpetual calendar

About twenty years ago, I used to keep on my desk—partly as ornament, partly paperweight, and somewhat as a useful device when I was writing fiction about the near future—a perpetual calendar like the one pictured here. It was a simple device: You align the month on the inner dial with the intended year on the outer dial, then read off the dates for the days of the week in the window at bottom. It took a minute to set, being mindful of leap years, and gave accurate readings over a span of fifty years.

This was a form of computer with no electronics and only one moving part. It was the sort of thing we all used to find specific information before we could carry a computer in our pockets that is the size of a deck of cards—and now wear one on our wrists that is the size of a matchbox.

I am of two minds about this, because I have always loved small devices with screens and keyboards. That love goes back to the first toy that my father made for me when I was about three years old. It was a box with a series of toggle switches and a line of small lights with red, green, yellow, and blue lenses. When you threw the switches, the lights would come on in different orders. It did nothing useful, except fascinate a small child. But it fixed my mind in a pattern that endures to this day.

Ever since the dawn of the Microprocessor Age, I have been chasing the ultimate handheld computer. It started with the first “personal digital assistants,” or PDAs, usually made in Japan and with crippled keyboards that required you to hold down three not-all-that-obvious keys to get a capital letter or a punctuation mark. Being a book editor and a stickler for form, I laboriously worked to get the right spelling and punctuation in my entries, so using the thing productively took forever. I then adopted, in rapid succession, a Palm Pilot—where you spelled everything out with a stylus or your fingertip—and then a variety of Hewlett-Packard calculators and tiny computers, chasing that holy grail.

My first cell phone had the traditional arrangement of rotary-dial numbers as a limited form of keyboard. That is, the digits 2 to 9 were each accompanied by three letters in sequence from the alphabet.1 You could store people’s names and numbers in the phone’s memory by “typing” them in using the keypad: Press 2 once for A, twice for B, three times for C, and wait a bit for the phone to sort out the right code and show your desired letter. And, of course, there were no lower-case letters or punctuation. It was really easier to keep your phone list separately, in a booklet or on a piece of paper, except that then your friends wouldn’t be on speed dial. But I digress …

Before we had computers at our fingertips, we had all sorts of handy ways to work out useful information.

The oldest is probably the Antikythera mechanism, a device of brass with geared wheels, now encrusted with corrosion and coral, discovered in a shipwreck off the Greek island of Antikythera in 1901. It has since been dated to about 200 BC, and x-rays of the gears and a reconstruction of their turning suggest that the mechanism was used to calculate astronomical positions and possibly to predict solar eclipses. The corollary would be the modern mechanical orrery, which dates back to the late medieval period and shows the positions of the sun and planets at any particular point in their continuously revolving orbits.

But mechanical representations of physical conditions are not the only form of ancient computer.

When I was compiling engineering resumes at the construction company, I came across a man whose work responsibilities included compiling “nomographs.” At first, I thought this was a typo and that he must actually be writing monographs—a literary pursuit, but an odd one for an engineer. Further checking revealed that, no, he really did make nomographs, also called nomograms. These are two-dimensional diagrams representing a range of variables associated with a mathematical function, usually shown as number sets along two or three parallel lines. Rather than solve the function mathematically, all an inquiring engineer had to do was draw a line of the correct angle across the parallel lines to achieve the answer.

As a form of computer, the nomograph is just a little more complex than a table of common logarithms2 or a telephone book—closer to a database than a calculation. And if we’re going to call a computer any device that gives you accurate astronomical readings, then a sailor’s sextant for “shooting the sun” at noon to determine latitude—and before that the astrolabe for calculating the angle between the horizon and the North Star—are also in the running as early “computers.”

But the point of this meditation is not to show how clever ancient peoples were but how much we are losing in the digital age. Orreries and sextants are now mechanical curiosities and decorative artifacts—the one lost to telescopes and observational satellites tied into much more sophisticated computer modeling, the other lost to satellite-based global positioning systems (GPS). Nobody writes nomographs anymore. The phone company doesn’t even publish the Yellow Pages anymore, or not on paper. Everything is online. And I can answer texts from friends by drawing letters with my fingertip—in both upper and lower case, with punctuation—on the crystal face of my Apple Watch, which doesn’t even need a keyboard.

The knowledge of the entire world along with real-time information, like GPS positioning and footstep counting with conversion to calories, is in our pockets and on our wrists. And that’s a wonderful thing.

But when the batteries die—or when future archeologists dig my Apple Watch out of a shipwreck, corroded with salt and perfectly nonfunctional—we will be left with lumps of silicon and dozens of questions. Who will draw the nomographs then?

1. Except for the 7, which picked up P, Q, R, and S, and the 9, which had W, X, Y, and Z. Presumably Q, X, and Z weren’t expected to get much use.

2. And a little less complex than a slide rule.

Sunday, February 16, 2020

Flying Cars

Taylor Aerocar

The Taylor Aerocar from the 1950s

So it’s now 2020 and the refrain I hear from all sides—including once on these pages—is, “Where’s my flying car?” We were promised in the tabloids and the Sunday supplements that our cars would fly by now. So where are they?

But let’s think about this a bit. First, what do you mean by “car”? Second, what do you mean by “fly”?

If a car is a vehicle that takes a driver and a number of passengers and their personal luggage on a flying trip of several hundred miles, then we had such a vehicle in my childhood. The Taylor Aerocar (pictured nearby) was available in 1954. Perhaps this vehicle fell short of the “flying car” definition because it didn’t just take off from the street. The owner trailed the two wings and tail section with its pusher propeller behind the vehicle on the road and then assembled the flight and control surfaces after arriving at the airport.

For a complete flying vehicle, we’ve long had small airplanes like the Cessna 172 Skyhawk, which can carry four people and their baggage about 736 miles at a top speed of 143 miles per hour. That’s a convenient flying distance and time, but the plane has to start and stop the trip at an airport or prepared landing strip.1 Also, the pilot needs a course of special instruction, must be licensed, and has to file a flight plan before each trip.

Both vehicles can actually fly, but neither can park in your driveway, roll into the street, and take off from there without FAA authorization and clearance.

As to the question of flight, a hovercraft would technically qualify as “flying,” although it seldom gets more than a few inches to a foot off the ground surface. So while you can travel with this vehicle across country and even over smooth water, the dream of taking your flying car up into the air, well above traffic, and over the rooftops cannot be satisfied with a hovercraft.

No, when we think of a “flying car,” we mean the sort of compact, wingless vehicle we all saw in movies like Blade Runner or The Fifth Element. There the cars occasionally might touch down and roll along the ground, but they mostly lift into the air and fly over and between buildings. We want our everyday parkable sedan but, you know … flying.

I have seen several designs and claimed pre-production models of such vehicles. Most use some assortment of ducted fans to generate lift and then, once aloft, forward motion. The ubiquitous aerial drone2 is a model for this sort of propulsion, using computers for control of its four to six rotors in maintaining stability and direction. Having a computer keep a flying car in level flight would go a long way toward removing one of the barriers to this concept, that of requiring the driver to maintain the vehicle in level flight and control it through all maneuvers and under all conditions of wind and turbulence, the way the pilot of a fixed-wing aircraft must constantly monitor the flight envelope. An extension of this computer control would allow the proposed flying car to maintain altitude separation, avoid collisions, and make protected takeoffs and soft, on-target landings. Indeed, the pilot/driver would only have to pick a destination and route, then sit back and become an interested observer of the passing countryside.

But the block to these cars becoming practical has more to do with energy than aerodynamics. It takes more energy to lift a body and maintain it aloft with a directed airstream like a ducted fan than to propel it forward through the air using an airfoil or wing to provide the passive lift. Even a helicopter provides its lift with an airfoil: those large rotor blades, which are so unwieldy in a parking lot. But small-diameter fans of the sort lifting any flying car we can envision will provide much less lift and so require more power.

Right now, four small but powerful gas engines driving the fans would consume about four times the fuel of an old-style Aerocar. And they would weigh more than the car’s performance parameters would probably allow.3 Electric motors would be far more efficient and infinitely more controllable, as well as quieter, but the battery weight and performance would again be outside the vehicle’s desired parameters. A flying car powered by internal combustion or electricity might have enough fuel capacity or battery charge to take you to the grocery store and back at low altitude, but it wouldn’t be much more than a rich man’s toy, like the very first automobiles: more trouble than they’re worth and bought only for the excitement and display value. Such a car would not be able to take you to the mountains or to Las Vegas and back for the weekend.

This is not to say that flying cars are impossible dreams, or that their development and practical use is more than a century in the future, if they are possible at all. But like so many other technologies we see in the movies, they wait upon developments in basic physics and in energy production, storage, and release that are still years away—even though some of our best academic minds, backyard inventors, and dreamers are working on the problem all the time.

In the meantime, as the link above shows, somebody’s got a working Aerocar for sale. All you need is a trailer.

1. And we won’t get into the questions of initial cost, regular service and maintenance, special storage requirements, and inspection intervals—all of which are much more intensive than for a regular family vehicle that would qualify as a “car.”

2. The lightweight kind with four small propellers and a camera on board, not an unmanned aerial vehicle (UAV) like the MQ-9 Reaper, which observes our enemies remotely and then rains missiles down on their heads.

3. Not to mention quadrupling service costs and time.