In this revised and expanded edition, William Gurstelle shows ordinary folks how to build a dozen fun and impressively powerful launchers with inexpensive household and hardware store materials. This new edition includes three new projects along with diagrams, photographs, and fascinating science information. With a strong emphasis on safety, the book also gives tips on troubleshooting and describes each machine’s historical origins as well as the science behind it. Workshop warriors and tinkerers at any skill level will love these new exciting DIY projects.
|Publisher:||Chicago Review Press, Incorporated|
|Edition description:||Revised and expanded edition|
|Product dimensions:||6.90(w) x 9.90(h) x 0.50(d)|
About the Author
William Gurstelle is a professional engineer who has been building model catapults and ballistic devices for more than 30 years. He is also a contributing editor at Popular Science, a columnist for Make magazine, and a frequent contributor to the Atlantic, Maxim, Wired, and other national magazines.
Read an Excerpt
EARLY ARTILLERY AND THE NIGHT LIGHTER 36
Prior to 399 BC there was no such thing as artillery. Ancient warfare consisted of hand-to-hand combat — club against club or sword against sword. In addition, warriors used thrown weapons like spears and stones, which were usually hurled from slings. Finally, they shot arrows from stretched bows. In 399 BC military leaders in the Greek city of Syracuse came up with ideas for larger, semistationary weapons that could wield much more power than could a single warrior's arm. These devices used animal parts, such as horns or neck tendons or hair, which had been fashioned into springs. By stretching these springs, a man (or even better, a group of men) could load the device with comparatively huge amounts of potential energy. These weapons were the earliest catapults and represented the first type of artillery.
From 399 BC until about AD 1330 all military artillery was powered by human or animal muscle. During this 1,730-year stretch, artillery took the form of siege weapons called onagers, trebuchets, ballistas, mangonels, petraries, and spring engines — all of which we now refer to by the general term catapult. Catapults work by suddenly releasing energy that has been loaded into the device by work from the operators' muscles. In ancient and medieval times catapult operators would tighten a rope spring, bend back an enormous bow made from wood and animal horn, or raise a great weight high off the ground. When a catapult is fired, a spring releases or a counterweight falls and, through a mechanism or lever, quickly and efficiently transfers its stored energy to the projectile.
Catapulting a bigger stone naturally requires a larger counter-weight or a thicker composite bow. By the end of the 13th century, catapults were getting about as big as they could get. The law of diminishing returns was taking over; making catapults any larger and more powerful would push the materials from which they were made to their mechanical limits. Moving and erecting the largest catapults already required gigantic siege trains and armies of men. An entire forest had to be cut to provide wood for such a device. Given the deforestation throughout Europe at the time, building such giant catapults became an ecological disaster as well as a logistical nightmare. Most important to kings and princes, they simply became an unacceptably large drain upon royal treasuries.
Such was the state of artillery warfare throughout the Middle Ages. But then a new discovery, brought by explorers and traders returning from the Far East, changed the world. The Chinese called this discovery the "fire drug." We know it today as gunpowder.
Fire-based, or incendiary, projectiles had been used in warfare dating back to the ancient Greek and Chinese cultures. Ancient accounts tell of baskets of flaming oil being hurled at enemies, arrows tipped with heads of burning straw, and even the Fire Ox, a Chinese innovation that is just what it sounds like — an ox with a barrel of flaming goo strapped to its hindquarters and sent stampeding toward enemy lines. But all of these were weapons of conflagration, not explosion. They spread fire, but they did not blow up with great and destructive energy.
Around AD 1000, the Sung dynasty in China began experimenting with the "fire drug," a compound of charcoal, sulfur, and a white powder that leached to the surface of the ground in certain areas. The white powder was potassium nitrate, which is often referred to as saltpeter.
By themselves, charcoal and sulfur do a pretty good job of burning. They release energy when ignited, but they do it rather slowly. The Chinese discovered that adding saltpeter to a mixture of sulfur and charcoal caused the compound to burn far more rapidly. And if the ratio of charcoal, sulfur, and saltpeter was exactly right, the compound would explode when heated in an enclosed space.
The Chinese military quickly made use of this discovery. They placed the fire drug mixture in various types of projectiles and bombs, giving them elaborate names such as "Bandit-Burning Vision-Confusing Magic Fire Ball," "Match-for-TenThousand-Enemies Bomb," and "Heaven-Shaking Thunder Crash Bomb."
The Chinese certainly knew this mixture was very powerful. Scientists now know that power is due to gunpowder having a fuel-oxidizer chemical combination. Things burn because they react with oxygen, and the more oxygen available, the better things burn. Saltpeter is an efficient oxidizer. When it is burned, a chemical reaction releases a great number of oxygen molecules that combine with the burning sulfur-charcoal fuel. The result is an ultra-vigorous energy release. When this reaction occurs in a closed container, an explosion results, creating a weapon worthy of the appellation "The Bone Burning and Bruising Magic Oil and Smoke Bomb."
Ancient chemists tried different proportions of charcoal, sulfur, and saltpeter and found that minute proportional changes resulted in much improved results. A bit more saltpeter and a bit less sulfur here and there would substantially increase the power of the chemical compound. Over time the experimenters found that the most effective proportion was about 75 percent saltpeter, 15 percent charcoal, and 10 percent sulfur. Once the correct proportions of the "devil's distillate" were determined, military men began to consider how to use it. One of the most straightforward applications was as a propellant for cannonballs.
One of the first trustworthy reports of the use of a gunpowder cannon (or at least primitive cannonlike technology such as a serpentine or culverin) in battle occurred in 1324. In the 14th century the city of Metz had become one of the largest in eastern France because of its position on the intersection of important trade routes. Rivaling some of the great cities of Flanders, Italy, and Germany, Metz was a tempting target for power-hungry noblemen. In 1324 the Dukes of Luxembourg and Lorraine attempted to take the city by force. According to the old chronicles, one of the leaders of the siege, William de Verey, sailed into the town onboard a flatboat, loaded not with horsemen or catapults but with new and secret weapons: things that had not been seen in warfare previously but that would be used in virtually all battles from that time onward.
An account written in 1838 by French historian J. Huguenin in Les Chroniques de la Ville de Metz relates that on this barge were "serpentines et canons ... et tirant plesieurs coptz de' artillerie" (serpentines, cannons, and many other types of shooting artillery). According to this town history, it was here, at the walls of Metz, that European besiegers first packed the new explosive called gunpowder into iron vases.
The chroniclers of the battle don't tell us what effect, if any, the primitive rock-firing cannons had on the outcome of the siege. Most likely, despite the presence of gunpowder cannons, the battle was won by the tried and true methods of medieval siege tactics: escalade (scaling walls with ladders), sapping (digging tunnels), frontal assaults, and subterfuge. But in a short time, artillery improved to the point where such medieval siege tactics were no longer relevant. Modern warfare probably got its start there, on a river barge filled with crude cannons that literally could not hit the broad side of a barn.
HIGH VOLTAGE AND NIKOLA TESLA
Our first project combines mechanical principles of explosive artillery warfare with the technology of electricity to produce a unique and powerful handheld spud gun. The Night Lighter 36 is a combustion-based cannon capable of shooting a potato from one end of a football field to the other. Its power and efficiency result from a high-voltage spark, thanks to the advances of electrical engineering. So it's important to look back at Nikola Tesla, who brought high voltage into daily life in a meaningful way.
Nikola Tesla was born in 1856 in Smiljan, Croatia. As a child, all who knew him realized that he was in possession of incredible intellect but was simultaneously plagued by myriad mental phobias and compulsions.
Tesla attended several schools and colleges, most notably the University of Prague, until he was banished for excessive gambling and "leading an irregular life." While in Prague, Tesla started work on what would be his most important contribution to science: alternating current, or AC.
Prior to Tesla's work, electrical power generation systems were limited to producing low voltages and high currents. Power companies had to either use very expensive, heavy copper transmission cables (to minimize wire resistance) or build a direct current generating station every mile or two. This low-voltage method, known as DC power distribution, was favored by the enormously rich and powerful American businessman Thomas Edison.
But high voltage, Tesla felt, was the key to the cheap and ubiquitous distribution of power, and using alternating current was the only way to achieve such distribution. He found a champion in a wealthy businessman named George Westinghouse. A brilliant and far-sighted entrepreneur, Westinghouse had built a giant business enterprise from nothing, making his fortune by manufacturing air brake systems for trains.
The new Westinghouse Electric Company was well financed, well managed, and most important, willing to base its entire business plan on Tesla's idea of AC power, which in almost every way was superior to DC. But Edison would not give up. Even if AC power was exponentially more efficient to transport and cheaper to make, it did have liabilities, and these he would exploit with a Madison Avenue–style public relations appeal to the public.
The Edison camp's plan was simply to portray AC power as too dangerous and deadly for use in homes and businesses. The PR campaign went something like this: AC power uses high voltage to transport power into people's homes. In fact, high voltages in and of themselves make the whole concept fly. But, said Edison's PR minions, high voltages are dangerous. If you accidentally touch high voltage, you can die. Today every room in every home and business has several 110-volt AC outlets, but in 1883 the idea of loading up your house with portals to such deadly currents was nearly unthinkable.
"AC power can kill you and your family," the Edison PR flacks said, and they backed up their claims with dubious tactics and statistics. Worse, they graphically demonstrated their point by electrocuting (with AC power, of course) scores of animals, barnstorming the country in a ghastly road show. The Edisonians fried scores of stray dogs and cats as well as farm animals (and in Albany, New York, an orangutan). The animal-electrocution cavalcade reached its cynosure with the Coney Island electrocution of a rogue elephant named Topsy.
But despite Topsy and the rest of the PR campaign, Edison's hope of discrediting Westinghouse failed, and soon Westinghouse's AC power was lighting the incandescent lamps of all electrified localities. Tesla's higher-voltage AC model won out: it was cheaper, faster, and just plain better.
In 1896 Tesla successfully installed a large AC power system at Niagara Falls, New York. The completion of that system ended the "War of the Currents," as this technology competition is popularly called. Soon afterward Edison's General Electric Company capitulated and converted to AC power.
Interestingly, New York City's electric utility company, Consolidated Edison, continued until recently to supply DC current to a few customers who had specialized needs for it, mostly for old elevators. Only in January 2005 did Con Ed announce that it would cease offering DC service to those 1,500 users, ending that chapter of electrical transmission history.
The Night Lighter 36
Spud guns are very popular amateur science projects. Few devices can be made as simply and inexpensively as a spud gun yet provide so much entertainment and fun. This project shows you how to make the Night Lighter 36, a transparent PVC potato cannon with a stun gun ignition system. It can be used both day and night, but the clear PVC tubing provides an excellent view of the internal workings when used in darkness.
The know-how for fabricating potato cannons is provided in many books — including my own Backyard Ballistics, which includes detailed instructions for making a simple yet dependable one — as well as on various websites. There are companies that sell the plans, parts, or completed spud guns over the Internet. Some products feature rather elaborate construction, including rifled barrels and metered fuel systems.
Most spud guns, however, are made at home. Having once mastered basic gun construction, the intrepid potato cannoneer often wants to design and assemble more complex and more artistic devices. The word artistic is applicable because making spud guns is an art as well as a science. For many, the act of shooting resonates on a primal level, and makers often take great pains to enhance their experience by continuously tinkering with their guns with the ardor of hot-rod builders and model railroaders.
The Night Lighter 36 potato cannon uses inexpensive modern circuitry to produce a stunningly high voltage that ignites a fuel-air mixture in the cannon barrel. It is a relatively simple extension of the basic spud gun concept and is fun to operate and entertaining to behold. A basic, no-frills spud gun can be built for less than $25. The Night Lighter 36 costs more due to the price of the transparent PVC tubes and the stun gun igniter. But with a bit of scrounging, you can often control costs. I built mine for less than $50 by finding odd pieces and leftovers from plastics suppliers. If the cost of the transparent PVC pipe is a problem, you can build this project using regular, nontransparent, schedule 40 PVC pipe.
Sanding drum for power drill
15/64-inch drill bit
(1) 14-inch-long, 3-inch-diameter transparent (or regular) schedule 40 PVC pipe
(1) 36-inch long, 2-inch-diameter transparent (or regular) schedule 40 PVC pipe
(2) Crimp-on barrel connectors
(1) Stun gun, nominal 100,000-volt output or better
(2) 2-inch-long, ¼-inch hex head bolts, full threaded
(4) ¼-inch hex nuts
(1) 3-to-2-inch-diameter white PVC reducing fitting
(1) 3-inch white PVC threaded adapter coupling, one side smooth, one side threaded
(1) Can PVC primer
(1) Can PVC cement
(1) 2-foot length of insulated 12-gauge wire
(2) Large crimp-on spade connectors
(2) 15-inch-long (not diameter) hose clamps
(2) Small wire nuts
(1) Tube of silicone sealant
Bubble wrap (optional)
Bag of potatoes
(1) 4-foot long, 1-inch-diameter wooden dowel or broom handle
(1) Can of hydrocarbon containing aerosol spray (hair sprays typically work well)
(1) 3-inch-diameter white PVC threaded end cap
PREPARE YOUR MATERIALS
1. First, cut the PVC to size. Measure and mark a cutting line 14 inches from one end of the 3-inch-diameter PVC pipe. Use the hacksaw to cleanly and squarely cut the pipe.
2. Now, measure and mark a cutting line 36 inches from one end of the 2-inch-diameter PVC pipe. This will be the cannon's barrel.
3. Fillet one end of the barrel as shown in diagram 1.2. Use a drill and sanding drum attachment to taper one end of the 2-inch-diameter pipe section so it forms a sharp edge. A clean sharp edge is important since it should cut the perfect-sized potato plug projectile as you ram the potato into the muzzle of the gun.
4. Drill a hole 4 inches from one end of the 3-inch-diameter pipe using a 5/64 inch drill bit. Drill a second hole of the same size, 4 inches from the same end, but at the spot that is exactly diametrically opposed to the first hole.
5. Now modify the barrel connectors. Using a sharp utility knife, remove excess insulation from the barrel connectors as shown in diagram 1.4. With the stun gun turned off (temporarily remove the battery for extra safety), place the connectors over the stun gun electrode to test the fit. Be sure to use the twin electrodes that point forward rather than toward each other.
Note: Depending on the make and model of the stun gun you use, you may need to modify these directions in order to connect the ignition wire to the stun gun electrode. Other types of connectors such as wire nuts and soldered connections may be used if necessary.
Excerpted from "Whoosh Boom Splat"
Copyright © 2017 William Gurstelle.
Excerpted by permission of Chicago Review Press Incorporated.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Table of Contents
Preface to the Second Edition,
1 Early Artillery and the Night Lighter 36,
2 The Jam Jar Jet,
3 Hired Guns and the Elastic Zip Cannon,
4 Sports Science and the Mechanical Toe,
5 Legendary Launchers,
6 Stadium Psychology and the T-Shirt Cannon,
7 The Architronito, Leonardo Da Vinci's Steam Cannon,
8 Bombastic Blowguns,
9 Xyloexplosive Devices,
10 The Whooshing Sky Puppet,
11 Little Ludgar, the Gravity Powered Hurling Machine,
Sources of Materials,