Your finger hovers over the red button, and you move the microphone close to your mouth. You test the public-address system and are relieved to find that it works: When you speak, your voice is clearly heard all over the firing range.

Several hundred feet away is the launch pad, and on it stands the culmination of many hundreds of hours of labor and many thousands of dollars of your hard-earned discretionary income. It is your rocket, a 15-foot-tall accurate scale model of an American early 1960s solid-fuel Pershing I nuclear ballistic missile. It is a machine that you designed and built from scratch.

Your rocket is loaded with two stages of powerful chemical engines. Like the original Pershing, your motive power comes from two stages of precisely packed chemical fuel arranged in solid form. Each rocket engine is designed such that after it ignites, the gas from the burning chemicals will issue rearward in a high-velocity high-temperature stream from the ceramic nozzle and propel the rocket up toward the stratosphere. Your rocket will reach empyreal heights, tens of thousands of feet—if all goes well.

You pay rigid attention to the preflight checklist. So far, everything looks like a go. There are small indicator lamps on the firing controls that signal launch status, and the ignition lamp shows green. This means that you have a working circuit, and so when the Fire button is pushed, enough current will be sent through the thin metal wire rammed into the motor to heat it red hot and thereby initiate the self-sustaining chemical reaction that occurs within the main motor's combustion chamber.

The countdown begins. Ten. Nine. Eight… At zero, you push the button and instantly great plumes of white smoke surround the base of the rocket. For a moment, the rocket doesn't move, and you too hold your breath. Then suddenly it leaps toward the sky with neck-jerking acceleration. The noise from the launch comes a split second after you see it leave, and when the noise does come, it is nearly deafening. The rocket climbs 100, 200, 500,1,000 feet, its speed escalating logarithmically as it ascends. It climbs and climbs, and it becomes difficult, then nearly impossible, and then totally impossible to see the rocket itself, although the smoke and nozzle fire remain visible.

Everyone congratulates you on a successful launch. There is applause and backslapping, high fives all around.

But the celebration is cut short by the sound of the range safety officer's warning horn: Whoop! Whoop! Whoop! The RSO's voice is plainly heard over the public-address system. “Attention! Look up! Look up! We have a rocket coming in hot!” This is not good for you. This is not good for anybody. In fact, this is trouble with a capital T.

What has happened is this: your rocket has two stages. The first stage consists of several large chemical rocket engines that lift the entire rocket for the initial or “booster” phase of the flight. When expended, the booster rocket falls away, and a second engine, mounted above it, is supposed to automatically ignite and continue powering the remaining components upward.

But the second stage, powered by its own very large engine, has ignited later than it was supposed to. In fact, it ignited after the rocket reached apogee and had already turned and begun to head back to earth. So the engine is not powering the rocket to fly up higher. Your rocket is being driven back down to earth not only by gravity, but also by the second-stage engine. There is a real danger that the rocket will reach the ground and your launch area before this engine is burned out and triggers the timed ejection charge that deploys the recovery parachutes.

The current situation is this: There is a very large and heavy rocket coming your way on an unpredictable descent path, and not just in free fall, but pushed by the thrust of a high-impulse, high-velocity solid-fuel rocket engine.

> > >

This is LDRS, the country's—and probably the world's—largest annual gathering of high-power amateur rocket enthusiasts. From all over the world, eager rocketeers come for a long weekend's worth of home-brewed acceleration and conversations about rocketry.

LDRS is an acronym for Large Dangerous Rocket Ships. It's the place where the people who started out as boys and girls experimenting with Estes and Centuri model rockets go when they want to build really, really big rockets of their own.

LDRS is sponsored by a group called Tripoli, which is the largest organization of high-power rocket makers. There are scores of local chapters or “prefects” in locations across the world. This year, Tripoli has chosen the Panhandle of Texas Rocketry Prefect to host the big event. The local leadership has been busy for months turning a large patch of cow pasture into the nation's most active rocket launching area.

Rocketeers both need and love wide-open spaces—the wider the better. Amateur rocket builders, especially those who specialize in building the largest and most powerful rockets, want only a couple of things: a lot of flat, open, unpopulated land in which to recover their rockets after flight, and clear, sunny skies. This makes places such as Texas, Kansas, and the Canadian prairie provinces ideal spots for LDRS gatherings.

The launch site is south of Amarillo, straight down the Interstate to the tiny hamlet of Happy, Texas. At that point, the route to LDRS follows Texas Ranch Road 287 east, a long, straight, and uncrowded chunk of pavement that goes through territory so flat you can practically see the curvature of the earth.

At the end of the long drive is the LDRS launch site, a sprawling temporary compound of tents, launch pads, electronics, and people. The level, open venue is perfect for facilitating the retrieval of the hundreds of rockets that will eventually drift back to earth during the event, attached by elastic shock cords to large white parachutes. This particular site has the additional and highly valued quality of being well outside all commercial air lanes, so the airspace above it has no scheduled flights. Even so, the Tripoli organizers had to apply for a certificate of special clearance from the Federal Aviation Administration, allowing very-high-altitude rocket flights during the three days of the event.

Central Texas can be brutally hot and bright in July, and the tents and E-Z Ups set up by the rocketeers and vendors provide the only shade. This meet has the air of a large crafts fair, except that the vendor booths contain recovery chutes, rocket engine casings, altimeters, and launch towers instead of decorated ceramic pots and fabric wall hangings. The east side of the area is dominated by rows and rows of missile launching pads.

In this heat, people are not inclined to exert themselves if they can help it, so most simply wander around the dusty field, working on their projects, talking to one another, and pointing. Spectators at a large-scale high-power rocket launch do a lot of pointing—always toward the sky, arms extended at about 70 degrees to the horizon. Their fingers trace out the rocket's acceleration skyward and then fall back down to their sides as they watch it float down on the end of a parachute or two.

Temperature notwithstanding, for a few days the formerly sleepy area becomes an energetic beehive of activity: smoke plumes and contrails constantly hanging like puffy ropes over the ranch, rockets roaring up, then silently floating down.

The great number of participants keeps several launching pads active. The pads with the biggest rockets are placed the farthest away from people, for it is not unusual for a rocket to blow up, or in rocket lingo, “CATO,” on the pad, producing a shrapnel rainstorm.*

*In the world of high-power rocketry, a CATO is an event that involves an explosive and unusually spectacular motor failure. It is one where all the propellant is burned in a spontaneous and drastically time-compressed fashion. There are several varieties of CATO. The propellant can blow out the nozzle, which is a loud but basically benign occurrence. Or the explosion can occur in the vicinity of the rocket motor's upper end cap, which usually destroys the rocket's recovery parachute and instrumentation. The most dangerous CATO is called a casing rupture. It is a sudden breach in the sidewall of the rocket tube, and almost always destroys the rocket completely.

The etymology of the term CATO is uncertain. Many rocket enthusiasts say it is an acronym for “catastrophe at takeoff,” “catastrophic abort on takeoff,” or something similar.

On the afternoon of the second day, a really big rocket, two and a half stories tall, stands erect on the far launch pad. It is a gracefully proportioned and aerodynamically shaped rocket and it is beautiful, at least to a high-power rocket enthusiast. Spectators and rocketeers alike press toward the safety fence to get into position for the best view.

This is the Athos II rocket, built by the Gates brothers of California. Athos II is a very large rocket with high-specific-impulse engines and will likely attain great heights. This launch is obviously going to involve significant velocity, complexity, and power. Athos's launch has been anticipated for quite some time, so the crowd near the safety fence is thick. People reach for their binoculars and position their cameras on tripods. Over the facility's loudspeaker, the launch control officer begins the countdown for one of the highlights of LDRS-21.

THE TECHNOLOGY OF HIGH-POWER AMATEUR ROCKETRY

In the typical solid-fuel rocket, the rocket maker builds a fiberglass shell that houses the motor, the recovery system, and whatever sensors, cameras, or other payload is placed within.* But the bulk of the rocket's weight is contained in its powerful chemical engines. In and of themselves, rocket engines are marvelous things. Their most basic form goes back to first-millennium China, when crude black powder was stuffed into bamboo rockets and used to frighten the enemy's horses. A simple rocket engine is straightforward and easy to understand. There is chemical propellant packed inside a metal casing. The chemicals inside the motor burn, and as they do so, hot, expanding gas is produced. This gas rushes out the back of the motor through a nozzle and, as described in Isaac Newton's Third Law of Motion, the backward gush of the gas results in an equal and opposite forward thrust of the rocket body. Simple, yes. But hey, this is rocket science, and things get complicated quickly.

Small, commercially available model rocket motors consist of black-powder propellant pressed under tons of pressure into a hard, dense matrix called “grain.” When the grain is ignited, the motor starts burning linearly, like a very fast-burning cigarette, from its back to its front. As it does so, it pushes hot gas out through a clay nozzle, and the rocket zips forward until the propellant is all burned up.

The world of high-power rocketry is different and much more complicated. Instead of using a simple black-powder chemical rocket motor, the experienced flyers most often use engines made out of “composite propellant”—a combination of an oxidizer chemical such as ammonium perchlorate (AP) and a synthetic rubber binder material to hold the oxidizer in a desired shape and provide

fuel. In addition, the rocket engine maker may mix in plasticiz-ers, catalysts, and crosslinkers, all of which can make the propel-lant burn stronger, longer, slower, or hotter, depending on the goals of the rocket designer. Composite motors are formed into various shapes with voids and holes precisely designed into the motor in order to shape the direction and velocity of the exiting gas. Such complex contours and figures are complicated to fabricate, requiring great quantities of heating, molding, curing, machining, and, above all, attention to detail.

The most extreme rocket makers spend days on end experimenting with rocket designs and motor formulations. There are so many variables that the maker can adjust to affect the performance of the rocket. A quick list of their concerns includes the shape of the rocket body, fin design, the shape of the nozzle, the geometry of the motor's core, the combination of various chemicals that make up the propellant mixture, the rate of burn, and the ignition method. It takes a lot of scientific, mechanical, and seemingly alchemical knowledge to become a really good rocket maker. There is also an element of danger working with toxic and flammable chemicals such as ammonium perchlorate, potassium nitrate, and liquid oxygen.*

*Former NASA engineer Homer Hickam wrote a popular book called Rocket Boys, and from it came the enjoyable movie anagrammatically titled October Sky. Both told the story of four teenage boys from Coalwood, West Virginia, who in the late 1950s designed and built a homemade rocket that flew nearly 6 miles into the sky. In one scene, Hickam and his friends start building their rocket engine by tamping down gunpowder encased in a metal pipe. This was not a good idea—and something far worse than property damage could have resulted. But the boys learned from their experience and eventually figured out the difference between building rocket engines and building explosive devices.

Apparently Hickam's experience was not peculiar to him and his friends. People, especially teenage boys, went rocket-crazy in the late 1950s, their interest spurred to stratospheric levels during the patriotic frenzy caused by the launch of the Soviet Sputnik satellite. In the late fifties and early sixties, thousands of young people attempted to build rockets. Few had any idea of what they were doing, so most wound up building what in reality were pipe bombs. Unarguably, mixing inexperience, a surplus of enthusiasm, and powerful chemicals resulted in a dangerous situation.

Estes Industries, the biggest name in manufactured model rocket engines, published a booklet called The Rocketeer's Guide to Avoiding Suicide. This booklet labeled those who engaged in the activity of building homemade rockets as “Basement Bombers.” It urged people never to make their own engines but instead to buy them premade.

According to Estes, about two hundred of the thousand people who responded to their survey said that a homemade rocket engine had caused serious injury to either them or someone they knew. The booklet provides example after example of rocket engine explosion injuries, some presented in gruesome detail: “He was making rockets out of pipes filled with match heads. The pipe blew up and he almost blew his stomach and intestines out.… He lost half a year of school.”

Perhaps Estes had a vested interest in persuading young rocketeers to buy their products instead of building engines from scratch, but irrespective of that, there did seem to be an extraordinarily high accident rate among youthful rocket builders of the time.

> > >

What rocket makers care about most is the physics quantity called “total impulse.” Total impulse is the product of the force acting on a rocket (the thrust) multiplied by the amount of time the thrust is applied. Expressed mathematically, it is:

Total Impulse = Average Thrust × Burn Time

An engine that applies a lot of thrust, for a long period of time, is a high-performance engine. To a rocket engine maker, the goal is lots and lots of impulse.

The size of a rocket motor and the amount of total impulse it produces are described by assigning the motor a letter of the alphabet. The smallest rocket motor is an A and is commonly sold in hobby stores without need for a permit. The B motor is twice as big as an A, and a C is twice as big as a B. Each increase in letter size denotes a doubling of the engine's rocket-lifting ability, or total impulse. The total impulse of an A-motor is about 2.5 newton-seconds (N-s), which is enough to lift a small rocket a few hundred feet. A B-motor provides 5 N-s, C-motors provide 10 N-s, and so on. The largest commercially produced rocket motor available to certified amateur flyers, the mammoth N motor, provides a muscular 41,000 N-s. Custom engines are available from a number of boutique rocket engine designers. Some of these go into the O and P range and even beyond. They are large and energetic enough to power a half-ton rocket to jet-fighter altitudes. (Using this scale, the NASA space shuttle's 8.3 million Newton-second booster rockets are about two letters beyond a Z-motor.)

Although there are many variations in the design and construction of homemade rocket engines, one of the clearest differentiating factors is the type of chemicals used to provide the energy and hence the impulse. The two most common general categories of chemicals are those involving variations of black powder and those that use composite propellant. Composite engines are, pound for pound, significantly more powerful than black-powder engines, that is, they have a higher specific impulse.

Every rocket engine, from black powder to solid fuel composite to liquid fuel to hybrid systems, works in similar fashion and is subject to the same basic physical laws: The propellant is ignited. It burns. Hot and expanding gases are produced and then stream out of a nozzle. Thrust is produced and the rocket and whatever is attached to it goes forward.*

The force produced by the gas issuing out of the nozzle is called “momentum thrust.” Imagine that a rocket engine builder constructs an engine with a burn rate of 10 pounds of fuel per second. Now further assume that the builder's rocket engine handbook tells him that his choice of rocket fuels will result in the gases leaving the rocket nozzle at a velocity of around 3,000 feet per second.

The thrust produced is equal to the propellant burn rate multiplied by the exhaust velocity. So the momentum thrust is:

Momentum Thrust = Propellant Burn Rate × Exhaust Gas Velocity

So, in the example above,

Thrust = (10 lbs/sec) × (3,000 ft/sec)/(32.2 ft/sec2)*
Momentum Thrust = 932 pounds of force

So far, so good. But momentum thrust is only part of the reason rockets go up. The other reason is pressure thrust.

Inside a rocket engine, there are unbalanced forces at work. The rocket engine has an open end (the nozzle where the gases come out) and a closed end. During the burn time, the combustion of rocket engine chemicals results in a pressure buildup inside the engine. But since one end is closed and one end is open through the exit nozzle, there is a net force pushing against the closed end.

For example, assume the action of the burning chemicals inside the engine results in the production of expanding gas, which in turn results in a combustion chamber pressure of 200 pounds per square inch. If the exit nozzle has an area of, say, 2 square inches, then the pressure thrust is equal to:

Pressure Thrust = Engine Pressure × Nozzle Area
Pressure Thrust = 200 lb/in2 × 2 inches = 400 lbs

The total thrust produced by a rocket engine is the sum of the momentum thrust and the pressure thrust. In this example,

Total Thrust = 932 lbs momentum thrust + 400 lbs pressure
thrust = 1,332 lbs total thrust

Finally, consider the amount of time that the thrust is applied. The longer the time, the farther and faster the rocket will go. The thrust times the amount of time the thrust is applied is the total impulse.

Itotal = Thrust × Time

So what does all this mean to the rocket designer? Plenty. The higher the propellant flow rate, the greater the thrust. The higher the velocity of the exhaust gases, the greater the thrust. The higher the combustion chamber pressure inside the engine, the higher the thrust. Taken together, there's a myriad of ways to increase impulse for any rocket.

But none of these factors is independent from the other factors. For example, the higher the flow rate, the shorter the duration of the thrust. A larger exit nozzle opening will result in more nozzle area but simultaneously less velocity in the exhaust gas stream.

Putting all of these things together is a challenging intellectual exercise, full of variables, trade-offs, and optimizations. And that in a nutshell is why rocket science is so darn complicated. >

THE ROCKETMEN

One of the best-known and most extreme rocket engine makers working in the Underground today is Frank Kosdon. Outwardly, he projects a nonconformist image and appearance: He is a tall man of indeterminate age with a napiform torso and thin legs, and his sartorial style tends toward ragged cutoff shorts and stained, shrunken T-shirts. His gray-black hair is beyond disheveled. Frank often fumbles his speech, and sometimes he struggles for words, but his eyes are bright and intelligent.

Frank earned his undergraduate degree in physics from Princeton and has a University of California doctorate. But he has chosen a lifestyle and career path distinctly different from those of most of his academic peers.

Kosdon has held various jobs. At the time of the Amarillo LDRS event, he earned most of his income in a couple of ways, both of which cause him to be on less than favorable terms with the California authorities. To meet “operational expenses” he often sells soda pop, beer, and wine coolers from the trunk of his Ford at the local nude beach. The local police don't condone either the nudity or the wildcat soda stand, and so there is friction.

The other thing Kosdon does for money is compound high-power rocket engines in his garage. Kosdon's motors are powerful and dependable, and provide a lot of bang for the buck. He has worked out all the intricate details—the nozzle geometry, the chemical composition, the casing design, everything required to make a powerful, hardworking chemical solid-fuel rocket motor. More than a few builders feel that Kosdon's solid-fuel motors are the Cadillacs of the high-power amateur rocket world.

At the time of the Amarillo launch, Kosdon's motors were high-demand items. In the early 1990s, a Kosdon-built rocket, launched from the Black Rock Desert near Reno, Nevada, held the non-government-entity world altitude record with an undocumented but widely believed height of 34,000 feet, which stood until fairly recently. But no Kosdon motors were flown at LDRS 21. There were some, well, issues.

Kosdon motors in the LMNOP range are said to be among the best, maybe the best. His fine craftsmanship aside, there is one big problem with Frank's motors, and it is this: His factory is located in his garage, which in turn is located in a densely populated Los Angeles suburb. Manufacturing rocket engines requires large quantities of chemicals—things such as the aforementioned ammonium perchlorate, black powder, metals such as aluminum and magnesium, plasticizers, epoxies, and other highly combustible items. Making a rocket motor requires heating, casting, and machining the chemicals. While this should not be overly dangerous when done by an expert such as Dr. Kosdon, such operations always present the possibility of an accident. A couple of years ago, a commercial high-power-rocket-motor factory blew up in a Las Vegas suburb, injuring several people and necessitating the evacuation of parts of the city.

Bowing to pressure from the Federal Bureau of Alcohol, Tobacco and Firearms, and the National Fire Protection Association, the organizers and safety committee of the LDRS launch won't allow Frank to sell his high-performance but non-ATF-certified motors at sanctioned meets such as this one.

At the launch site, one person asked Kosdon why he does business in the unauthorized and unorganized fashion he does. After all, a big rocket motor can cost more than $500, so this could be a viable business. But this is where rocket making starts to get a little political. A small but significant number of Underground members do not trust the government. Many of these are just moderately untrusting, but some of the more extreme don't trust it like, say, Idaho survivalists or Branch Davidians don't trust it. After a few beers, eventually some will start to explain. They talk of a broad national conspiracy on the part of ATF, NASA, the FAA, and others to stifle the activities of amateur rocket makers.

Why would the federal government give a hoot? It is because a few of the rocket men—among them the most extreme and the most talented—want to build extremely large rockets. And, according to some, building such large rockets is perceived as a threat to federal government interests. They believe the government will do everything it can to maintain its monopoly on space travel and commerce. The future is in space, they say, and the feds want it all for themselves.

“We're regulated and opposed at every turn,” explained one of them. “The government put ridiculous and onerous rules and regulation out on everything from the purchase and use of chemicals like AP to making it impossible to fly our rockets at even relatively low altitudes like 20,000 feet, and even in the middle of the Nevada desert. Can someone explain to me why I can't go to, say, Australia or the middle of the ocean to launch my rockets? The government says that because we're U. S. citizens, they still have jurisdiction over our actions, even if we launch outside of Perth or from a boat beyond the 50-mile territorial limit. That's not fair, and it's not American. NASA wants to maintain their monopoly, and I think they'll stop at nothing to do so.”

Even the much more numerous mainstream rocket flyers—those who don't have their own plans for exploiting outer space—often have issues with the federal government. The ATF took strong legal action in 2001 that amounted to a crackdown on the sport, enacting stringent rules regarding the storage, transport, and sale of the stuff that makes the whole activity go, ammonium perchlorate. Angered by the actions, rocket hobby associations such as Tripoli and the National Association of Rocketry started a legal battle with the Bureau over its regulations, and the battle continues. As usual, the only winners have been the lawyers.

So Frank Kosdon attends the Amarillo LDRS event strictly as an observer, since the event organizers don't want the government scrutiny that the use of his motors would cause. Instead of selling motors, he reverts to his other business interests, covering the cost of this trip to Texas by selling soda and beer from the trunk of his Ford.

Kosdon's home and workshop is located in a modest but well-tended section of the endless urbanized area that stretches north of Los Angeles toward Santa Barbara. Unlike his neighbors' houses, Frank's is not particularly well-tended or even neat. There are no window shades to hide the boxes upon boxes of rocket parts stored hither-skither in his living room. His house is so full of stuff that in most rooms there are only narrow aisles cleared for movement. Almost every cubic inch of space is filled with packing boxes, ceramic nozzles, the metal turnings that make up rocket motor cases, and above all, junk. Magazines, newspapers, and old telephone books, many dating from the early 1990s, form mazes of unstable columns reaching almost to the ceiling.

“I build rocket engines because I like it and because I'm good at it, mainly,” he says. “It's hard to make money with this. The government does everything they can to stop a guy from making a living. But if you do still manage to succeed, they'll tax the hell out of you. Feel free to quote me on that.”

Just a few miles down the Pacific coast from Frank Kosdon's wild jumble of a house is the home of another extreme tinkerer, an amateur rocket builder named Dirk Gates.

Dirk and Erik Gates are southern California brothers who are among the very highest flyers at LDRS. They build and fly some of the largest amateur rockets, including the Musketeers of the sky, Athos, Porthos, and Aramis. The Gates brothers possess the two things that are necessary to excel in the Technology Underground: dedication and money. The Gateses, especially Dirk, have plenty of both because Dirk made a fortune in the overheated high-tech stock market of the late 1990s and sold his PC-card-making business, called Xircom, to Intel at just the right time.

Money, experience, and free time allow the Gates brothers to pursue their interest with a professional's competence and a hobbyist's ardor. Over time they have compiled an unparalleled panoply of large, high-power rockets that they truck around the country in a handsomely painted trailer. Professional stock-car racers and country western headliners should have a vehicle this nice.

Although the distance between Frank Kosdon's and Dirk Gates's homes is only 50 miles or so, the gap between them is vast. The approach to the Gates house is fronted by a massive, ornate steel gate, protected day and night by uniformed security men in a guardhouse. After the security checkpoint, a winding road flows past mansions reminiscent of fairy-tale castles. Gates lives in a California-style house that rambles on and on up the side of a hill. In a work space that spans several bays of the eight-stall garage, Dirk and his brother have set up the equipment to build some of the highest-flying rockets anywhere.

The Gates brothers make an unusual pair. Dirk is the quiet, unprepossessing one, but, no doubt about it, he's a driven engineer. A scorekeeper and technocrat, he built his computer company into a billion-dollar enterprise in a very short time. He works on his rockets and related paraphernalia in the garage, a 2,000-square-foot structure with 14-foot ceilings and composite-resin flooring instead of concrete, ringed neatly with cavernous white melamine cabinets holding tools, supplies, and miscellaneous sundries.

Erik Gates has different priorities. He appears more of a thrill seeker than a guy who loves business. Erik is a member of an elite bunch of just-outside-the-law adventurers who call themselves “BASE jumpers” and are known for parachuting off things that are not airplanes—for instance, bridges or tall buildings. It's an underground fraternity, since most municipalities do not allow people to jump off office towers. Despite the frequently illegal nature of the activity, it is often practiced, and for people like Erik Gates it's a passion. BASE is actually an acronym for building, antenna, span (meaning a bridge), and earth (usually a tall cliff), the four different types of non-airplane parachute jumps that must be accomplished in order to be considered a true BASE jumper.

“Both Erik and I have always been interested in this kind of stuff,” Dirk said. “Our dad was an aeronautical engineer, and we always tinkered around with him. But you can only go so far with your dad. In seventh grade, I found a book in my junior high library, believe it or not, that told me how to mix up a batch of gunpowder. I still remember how I felt when I found out that the secret to this stuff was to mix just the right proportion of three ingredients by weight together in a closed container, and then ignite it. We found sources for charcoal, sulfur, and saltpeter and ground them all down to a fine powder. We had a chemistry set at the time that had a burner that could melt and shape glass. So we put the gunpowder mixture inside a glass tube along with a Nichrome fuse and sealed the ends shut by softening and sealing the glass with the Bunsen burner.”

Erik continued, “One of the neighbor kids had a dollhouse that was made from concrete blocks. We set the filled glass tube in there and set it off. There was a pretty big bang and we kind of wrecked the dollhouse, what with all the glass fragments and shrapnel.

“No police showed up. I wasn't surprised that they didn't, because it wasn't that big a deal. At least it wasn't back then, because people didn't seem to care so much about activities like this. The only time we got in real trouble was when we filled up a trash can with flammable gas. We used one of those MacGyver-type reactions to fill up a Hefty bag with hydrogen. Something to do with aluminum foil and household cleaners.”

Dirk went on, “That was pretty clever for kids our age. When we lit it, we got a bigger reaction than we expected. It actually started a grass fire in our backyard and the fire department came out. We didn't get in trouble, though.”

At the Amarillo LDRS launch site, the Gateses' Athos II roars into the sky with the force equivalent of a locomotive engine pushing it upward, with the fast-burning combination of ammonium perchlorate and plasticized fuel combusting and spilling madly out of the ring of exit nozzles. Tightly packed within the rocket engine array, each M-sized motor fired with approximately 1,400 to 1,500 pounds of force, putting the combined thrust in the neighborhood of 10,000 pounds. This is an amazing amount of thrust for a couple of amateur hobbyists to produce. During the period of main engine ignition, this lightweight rocket is pushing as hard as a small jetliner or a medium-sized tugboat. The orgy of thrust, flames, power, and smoke sends the rocket several thousand feet in just a few seconds.

When the booster rockets burn out, they fall away, and the main rocket body continues to climb in unpowered ballistic flight until the massive second-stage engines kick in. The second-stage motor, a combination of M- and J-sized engines, air-starts and sends the rocket farther still until finally gravity catches up and grabs it somewhere between four and five miles up. Then the rocket turns and begins its descent. Inside the rocket body, barometers sense the change in the rocket's direction and fire the parachute ejection charge, and the Athos II floats back down, exhausted but triumphant.

> > >

There's plenty of excitement at LDRS right now. Your big multistage rocket with the failed chute-ejection charge continues to barrel on down. It's descending fast and getting faster.

Life has its exposure risks, such as secondhand smoke, mosquito-borne viruses, and asbestos and radon lurking in your basement. Those who choose to attend high-power rocket meets must accept this additional one as well. The horns keep up their whoop-whoop-whoop as everyone nervously stares upward at the plume of smoke denoting the rocket plunging earthward on a kamikaze trajectory.

The range safety officer is the person responsible for the safe operation of the event, and he is very concerned. The rocket is large enough and heavy enough to wreck a car if it plows into one, and if it hits a person, that would be far worse. It's too late to evacuate, so the people on the ground must be ready to run.

Finally, and to everyone's great relief, the altimeters and angle sensors on board figure out what's going on. A puff of smoke appears in the sky, immediately followed by the preliminary or drogue chute, and then the main chute—a big white and orange pillow of cloth.

The rocket body slows rapidly and then floats down, pushed by gentle winds out to the cow pasture, where a group of young men on all-terrain vehicles retrieve the fuselage. Your rocket lives to fly again.

> > >

In 2004, the first homemade rocket to break the government monopoly on reaching the official limits of outer space (100 kilometers up) made its successful launch from a place in the northwestern corner of Nevada. Most of the time, there's not much going on there. It's an area known as the Black Rock Desert, a flat, dusty, windy, unpopulated dry lake bed, called the playa. Black Rock is a much-favored location for high-power amateur rocketeers to try out their largest and most powerful motors.

In 1997 the playa accommodated a supersonic land speed attempt by the British SSC Thrust jet car, which hit a speed of 763 mph, or Mach 1.02.

Aside from technology record attempts, not much would seem to occur on the Black Rock Desert's playa to make it qualify as a high-energy hot spot—except for one particular time of the year. Then, for a week in late summer, the playa comes alive with unbelievable energy and activity.

*Tripoli regulations forbid the inclusion of mice, hamsters, frogs, or small children as payload.

*But why does the rocket tube go forward? Two reasons. The first is because of the immutable physical law called “conservation of momentum,” described by Isaac Newton in his Laws of Motion. Imagine a man sitting in a small boat in a still pond with a lapful of baseballs. He starts throwing the baseballs toward the back of the boat. Every time he does so, the boat goes forward. The harder he throws, the farther forward the boat goes. If he throws one ball after another, the boat moves continuously in the opposite direction.

*Where did that 32.2 ft/sec2 term come from? That's a conversion constant due to the acceleration of gravity and is needed to convert pounds-mass to pounds-force.