Brief History Of Computers In Ballistics

It is well known nowadays that the modern science of ballistics owes much to the development of electronic computers. But, it is not so well known that the development of modern computers owes at least as much to the science of ballistics. Nearly fifty years ago, the U.S. Army Ballistic Research Laboratory put the first high-speed electronic digital computer into operation. It was designed and built by engineers from the University of Pennsylvania under a contract let by the U.S. Army Chief of Ordnance. Completed in 1945, it was nicknamed the "ENIAC," which stood for the Electronic Numerical Integrator and Computer. The ENIAC was designed and built primarily to provide faster and more accurate calculation of the trajectories of bombs and gun-fired projectiles. Built before the invention of solid state electronics and miniaturized circuits, it contained about 19,000 vacuum tubes, 1500 electromechanical relays, and innumerable smaller parts. It weighed about 30 tons and consumed nearly 200,000 watts of electric power. Its computing capabilities were probably less than those of most modern desktop PCs, but it was nevertheless a truly remarkable achievement for the time. Its completion contributed significantly to the defense capability of the United States and our allies; but, perhaps even more important, it represented a giant step forward in the development of modern digital computers.

Though the science of ballistics is now about 300 years old, the study of ballistics as an art is older than the invention of firearms and so is the use of computing machines. The English word ballistics is derived from the Latin word ballista, the name given by the ancient Romans to a war machine that could hurl javelins, stones or other missiles, powered by the elasticity of twisted skeins of animal sinew. The abacus, a primitive computing machine, has existed in the Orient for at least five thousand years. Wars have been waged in the Orient since the dawn of history, and so we might reasonably speculate that the first computing machine applied to the study of ballistics was the abacus.

Computing machines are of two general types, digital and analog. The abacus is a primitive example of a digital machine because it consists of several parallel rows of small blocks or beads each of which represents an individual digit. The value of each bead depends upon the row it occupies and its position in that row. The slide rule, which was standard equipment for the working engineer before the advent of pocket calculators, is an analog computing machine, so called because the infinitely variable positions that can be taken along its logarithmic scales are analogous to the variables involved in the calculations.

The slide rule principal has also been used in some interesting computing devices intended exclusively for ballistic calculations. One such device was the military Graphical Firing Table (GFT) which was used by field artillerymen to solve gunnery problems during World War II. Some shooters will also be familiar with the

Speer Ballistics Calculator, the Powley Computer for Handloaders, and the Powley PSI Calculator, all ingenious slide rule devices invented by Homer S. Powley for making ballistic calculations. As late as the 1950s, there was in use at the U.S. Army Aberdeen Proving Ground a film slide rule consisting of greatly expanded slide rule scales marked on the edges of 35mm motion picture film so arranged that the film could be moved through a special projector and the scales could be read very accurately from the magnified images on the screen.

The first practical electronic analog computers also were built under supervision of U.S. Army Ordnance, at about the same time as the ENIAC, specifically for the purpose of solving complex problems in ballistics. The gunnery problems facing antiaircraft artillerymen before the days of "smart" surface-to-air missiles were incredibly difficult. To hit an airplane flying hundreds of miles per hour at a distance of thousands of yards with a single projectile from an antiaircraft gun is a feat comparable to bringing down a very distant high-flying duck with a single shot from a rifle.

The invention and development of tracking radar during WWII provided the capability of following a target airplane accurately while constantly measuring the range and the horizontal and vertical angles to the target. The path of the projectile and its time of flight to any point in space could also be calculated provided the muzzle velocity of the gun, the drag characteristics of the projectile and the prevailing atmospheric conditions were precisely known. The task to be done was then to constantly process the information on the path and speed of the target being tracked by the radar and thereby predict its future position. Simultaneously information about atmospheric conditions, muzzle velocity and ballistic properties of the projectile was also included to determine its time of flight and therefore, the lead required to aim and fire the gun so that the projectile and the target would arrive at the same distant point in space at exactly the same time. The timely solution of this complex problem was beyond the capabilities of any calculating machine then existing. Therefore, special purpose analog computers were designed and built during the 1940s for that specific purpose. They became the first practical, mobile radar tracker/

detector systems. The beneficial spin-off of this work paved the way for development of other modern analog computers as well.

Software as we know it today was not used in the early computers. At first, programming the computer required actually changing connections of the wires that linked the various electronic components so as to perform each particular calculation. Later, input devices were developed so that explicit instructions could be given to the computer in the fundamental "machine language" which it "understands," but which would make no sense to any human except the specially trained programmer. Computer programming was, in those days, the exclusive province of professional programmers. Early input devices included punched cards and punched paper tape, followed later by magnetic cards and magnetic tape and, later still, by the direct keyboard entry, the magnetic disk, the light pen, the mouse, the optical scanner and other input devices that we use today.

Machine language requires that a problem to be solved must first be translated into code which bears no apparent resemblance to the original terms and numbers of the problem. That translation is difficult and time-consuming; and, even highly trained programmers make errors in the translation that are very hard to find. To overcome these difficulties, computer languages were soon developed, shifting much of the burden of translation from the human programmer to the machine itself. The programming language first and most widely adopted for mathematical and scientific use is called FORTRAN, which is the acronym for "FORMULA TRANSLATION." There are, however, many other programming languages now in more or less common use. Among these is BASIC, which stands for "BEGINNER'S ALLPURPOSE SYMBOLIC INSTRUCTION CODE." As the name implies, the language and methods of BASIC closely resemble the common language and methods of problem-solving with which many people are already familiar. Thus, the usefulness of computers was extended to a group much wider than that of professional programmers. Consequently, beginning in the 1970s, the way was opened to the development of reasonably affordable personal computers.

A personal computer program for the accu rate calculation of trajectories was published in the American Rifleman magazine of June 1983. Written in 1979 for the Radio Shack TRS-80 Model I, one of the few personal computers then available, this program appears to have been the first of its kind. With the phenomenal proliferation of personal computers during the 1980s, a great many other programs of interest to shooters have now become available, not only for the calculation of trajectories, but for other tasks as well.

Personal computers are now available at about the price of a high-quality rifle, and most of the programs require no special skill or knowledge of computer programming. The personal computer has taken its place alongside the modern electronic chronograph in the equipment of technically advanced, non-professional experimenters.

Though certainly not essential to the enjoyment of shooting and reloading, these sophisticated instruments have extended the capabilities of non-professional ballisticians into regions which were, until quite recently, the exclusive province of workers in professional ballistics laboratories. The technically inclined shooter who invests in a personal computer and learns the relatively simple rules for its use will almost certainly find his time and money well spent.

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