'It's All About Fire, Smoke, and Noise'
You know those little rockets made of wood and glue that you can stuff a motor in and launch from the field next door? These aren't them.
- By Preston Lerner
- Air & Space magazine, January 2004
AT FIRST GLANCE, IT'S A SCENE STRAIGHT OUT OF A Norman Rockwell painting: father and son bonding as they kneel to insert an igniter into the base of a model rocket. But the kid isn’t nine-year-old Nick Braye; it’s his dad, Randy. And their toy rocket isn’t one of those lightweight jobs you can set off in your back yard. It’s a fearsome eight-foot-tall projectile powered by a solid-propellant motor similar to those in the space shuttle’s 126-foot strap-on boosters, and it appears to be fully capable of taking on cargo–or taking out an F-16, for that matter. Ideally suited, in other words, to the mega-launchfest known as Large and Dangerous Rocket Ships.
Despite the ominous name, LDRS isn’t a workshop for budding Dr. Strangeloves. It’s the world’s largest annual celebration of high-power rocketry—serious projectiles, launched by serious adults, that fly exponentially higher, faster, and farther than the balsa-and-Elmer’s-glue creations of yore. The first LDRS, an outlaw event held 22 years ago, drew 47 entrants, onlookers, and groupies. This year’s gathering, in Argonia, Kansas, featured thousands of spectators and more than 500 rocketeers, flying everything from scale-model V-2s to a technological marvel that has a Federal Aviation Administration waiver to exceed 30,000 feet.
With more than 150 pounds of thrust, Braye’s Bobcat—so named because it wears the colors of his Marshalltown, Iowa high school—represents the heart of high-power rocketry. So too does the middle-aged Braye. “I was a child of the Space Age,” he says. “I flew my first rocket in 1968, built three Saturn Vs, had a National Geographic map of the moon on my wall so I could plot where every mission landed. But then I found out about girls and cars, and I forgot about rockets in 1971. I didn’t get back into them until 1997. I wanted to buy my son a birthday present, and when I started snooping around the Internet, I couldn’t believe how much rockets had changed. I thought to myself, Wow, they’ve got some really big stuff now.”
Braye is what’s known as a BAR—a born-again rocketeer. Hundreds of others with eerily similar stories have braved 100-plus-degree heat to congregate in a field an hour southwest of Wichita in what is, if not technically the middle of nowhere, then not far from it. The organizers of LDRS XXII have set up 50 launch pads, each wired to a central launch control panel. The smallest rockets are lit off a few yards from the viewing area. The biggest boomers, meanwhile, must be trucked to a pad a half-mile away.
Braye and his son secure the Bobcat to a vertical launch rod welded to a metal plate that will shield the ground from the blast of the rocket. The rod is designed to guide the Bobcat into a vertical launch; otherwise it will slew sideways and become what rocketeers call a land shark—a rocket that comes off the launch rod and slides along the ground under power. Braye puts his ear to the Bobcat’s casing to make sure the altimeter is beeping properly. “Please work like you’re supposed to,” he murmurs before he and Nick clear the pad as the launch control officer prepares to trigger the ignition. The P.A. system announces: “Randy’s flying a scratch-built rocket on an AeroTech K695R motor. Randy’s rocket is going in 5-4-3-2-1.”
The rocket ignites with a sibilant roar. Liftoff has none of the gravitas of a Saturn V launch. One second, Braye’s rocket is on the pad; next, it’s 200 feet high, 500 feet, 1,000 feet, zooming on a bright red flame. After two and a half seconds, the motor cuts out, but the rocket silently keeps on climbing–4,000 feet, 5,000, 6,000. Braye and his son crane their heads and steeple hands against foreheads to follow the Bobcat’s progress. “C’mon, baby,” Braye urges. “Come on!”
Seconds later, Nick says, “I think we’ve got a chute.”
Like most high-power rockets, the Bobcat has a two-stage recovery system. Shortly after the altimeter senses that the ascent has ended, it ignites a black-powder charge that splits the rocket into two pieces (that remain connected by a nylon shock cord) and ejects a small drogue parachute. The full-size parachute will be deployed after a second charge causes the nose cone to separate when the rocket descends to a pre-determined altitude—in this case, 300 feet. At least, that’s the theory.
“Nothing’s coming out,” Braye says glumly as he tracks the Bobcat’s progress. “It’s all still together. Nothing’s coming out.”
Meanwhile, other rockets lift off. Whoosh: There goes a Performance Rocket packing a J350. Whoosh: Wave goodbye to a homebuilt flying on a honking M1850 Green Gorilla (so called because barium causes the flame to burn green). But Braye has eyes only for his Bobcat. “Now,” he whispers. “Now! Open now!”
Suddenly, finally, the parachute pops out. “Yes!” Braye shouts, pumping his fist. The rocket floats down under a black and orange canopy and lands in a plowed field. Braye lopes over to pick it up. By the time he gets back, his son and wife Penny are lounging in the shade. “You know how high it went?” Braye asks. He works the altimeter, which beeps in response. “You know what that means, Nick? Sixty-six-forty-one,” Braye crows. “Six thousand, six hundred, and forty-one feet! Isn’t that something?” Nicholas and Penny seem only mildly impressed, but Braye is too jazzed to notice. “In a half-hour,” he says, “I could have this thing cleaned up, stick another motor in it, and be ready to go again.”
In terms of fundamental architecture, rockets are simple devices. Load a combustible propellant in an enclosed chamber, light the fuse, and thrust is generated as the resulting gases expand, accelerating through the exhaust nozzle. The Chinese were launching rockets centuries ago with a mixture of saltpeter, charcoal, and sulfur. Black-powder propellant is still used in modern fireworks and small model rockets. But it’s an inefficient fuel, and its use stunted—literally—the growth of amateur rockets when the sport took off during the 1960s. Liquid oxygen and kerosene was a powerful alternative; after all, liquid oxygen and liquid hydrogen sent rockets to the moon. But LOX is a don’t-try-this-at-home product. And while rocketeers who wanted to push the propulsion envelope used various other fuels, all were either too dangerous, too complicated, or too expensive—often all three—for widespread use.
High-power rocketry is a product of the development of so-called composite motors, which feature a witches’ brew of ingredients. Known as AP motors because ammonium perchlorate serves as the oxidizer, most composites consist primarily of a plastic binding agent and a hard rubber fuel called HTPB, for hydroxyl terminated polybutadene, that is molded to fit in the motor case. Unlike their liquid-fueled cousins, solid-propellant motors don’t explode in a fireball in a launch mishap. Also, composite motors provide far more bang for the buck (and ounce) than black powder.
“When I got involved, I didn’t realize how many brownie points Tim would get for having a wife who flies rockets,” says Beth Sapp of West Tawakoni, Texas, whose husband and two sons are avid rocketeers. “But he’s created a monster. I became a high-power junkie. Now we have to fight over who’s going to get to use the next big load of AP.”
High-power motors are described with codes like “K550.” The number is the average thrust in newtons, the force required to impart an acceleration of one meter per second squared to a mass of one kilogram (one newton equals 0.2248 pound of force). The letter rates the total impulse, or overall power, of the motor. (Dividing the total impulse by the thrust provides the duration of the burn in seconds). Each successive letter denotes a motor that is twice as powerful as the one that precedes it—a B motor is twice as powerful as an A, and a C is twice as powerful as a B (and four times as powerful as an A). A small A motor produces less than one pound of average thrust. An I motor, a common mid-power choice, might generate 50 pounds; a popular high-power M, closer to 500. Although Qs and Rs have been flown elsewhere, the largest motor at this LDRS is a P, rated at 1,800 pounds of thrust. By comparison, the Redstone that took Alan Shepard 116 miles above Earth pumped out 78,000 pounds of thrust.
Back in the 1960s and ’70s, virtually all model rockets went up on black-powder motors no larger than D; there were only a handful of Es, Fs, and Gs. Sure, a few radical types clustered these motors together for additional pop. But the party line at the National Association of Rocketry was: Big is bad. So it was left to a few California renegades to challenge the status quo. One, Gary Rosenfield, later founded AeroTech Consumer Aerospace, which is now the world’s largest manufacturer of hobbyist rocket motors. Another, Chuck Piper, became the chief guru of the Rocket Ranch research and development facility in a canyon near Patterson, California.
By 1981, Piper’s big-iron launches in the Nevada desert were so legendary—or notorious, depending on your perspective—that past National Association of Rocketry national champion Chris Pearson flew out from Cleveland to see one for himself. “Half of the rockets blew up on the pad,” Pearson recalls. “But I came home determined to put on a high-power rocket meet.” The next year, he staged the inaugural Large and Dangerous Rocket Ships in Medina, Ohio.
From the beginning, the name was tongue in cheek. Nevertheless, NAR’s high priests went ballistic. They excommunicated LDRS participants and declared anybody involved in high-power rocketry a heretic. And to be fair, there were big problems associated with the small community. “We had people moving from model rockets to high-power who thought they could continue to use paper tubes and white glue on wood fins,” says Bruce Kelly of Orem, Utah, who edits and publishes High Power Rocketry magazine.
Some oversight was needed. Since NAR wasn’t willing to provide it, the Tripoli Rocketry Association, which had been formed by enthusiasts in Pittsburgh, reconfigured itself as a national organization and became the governing body of high-power rocketry. Tripoli and NAR have long since kissed and made up and have created a rigorous certification process for rocketeers who want to fly high-power motors. Generally speaking, though, NAR focuses on model rocketry, roughly defined as motors size H and smaller, while Tripoli concentrates on high-power and experimental (homebuilt) motors.
Most rockets are built from kits that must be assembled, sanded, painted, and so on. Estes dominates the entry-level market, selling small wood-and-glue kits and black-powder motors that cost as little as $3. Naturally, bigger motors require stronger airframes, typically fiberglass or a heavy-duty reinforced cardboard called phenolic. Also, higher altitudes demand more sophisticated recovery systems. A high-power rocket equipped with two parachutes and a fully equipped electronics bay can fly to 5,000 feet on an expendable J motor for less than $350. But as the motors get bigger, prices soar.
Rocket motors are built for aluminum cylinders that come in standard diameters, from 29 to 98 millimeters (about an inch to nearly four inches). The propellant is molded into fuel grains (also known as slugs or chunks), which look like spools and feel like pencil erasers. The grains are sized to ensure an even burn, and there are usually several in each motor instead of one big one. The grains are loaded in the case like batteries in a flashlight. Close both ends, attach a graphite exhaust nozzle, and the motor is good to go. And in the 1980s, once it went, it was gone for good.
Enter the reusable motor. “I knew motors would cost a lot less if we could just sell the part that burned off—the fuel grains,” Rosenfield says. “And I felt that people would enjoy putting their motors together.” Aluminum cases last forever if they’re not lost or damaged in a CATO, which rhymes with “Playdough” and is short for “catastrophic failure.” The hardware for a 54-millimeter (two-inch) motor like the one the Bobcat uses is about $60. But Braye’s principal cost per flight is the reload kit, which runs $90.
LDRS isn’t the Promised Land for amateur rocketry extremists: That would be Black Rock Desert in Nevada, where Tripoli holds an annual National Experimental Launch. But the LDRS offers more variety than any other gathering.
Of the 1,200 rockets launched during six days of flying, 37 go up during a single high-power drag race. Solo launches include a model of The Big One featured in the movie Toy Story and an even bigger model painted in black and white blotches and named Udder Madness. (Alas, it CATOs on the pad.) One joker lights off a rocket made of cardboard packing material secured with Postal Service tape. Another flies a rocket made of Legos. Ky Michaelson goes both of them one better. The self-proclaimed Rocket Man, who built 13 rockets for the celluloid paean to amateur rocketry, October Sky, flies a Porta-John on a pair of M500s.
After several failed attempts, a group from Dallas launches a quarter-scale model of NASA’s never-flown X-30 lifting body. It’s one of a small number—perhaps five percent—of the rockets flying at LDRS with a hybrid HyperTEK binary-fuel motor. Although hybrids are disparaged as “farting rockets” because of their flatulent roar, they’re less expensive than the more closely regulated AP motors. (And after 9/11, the Bureau of Alcohol, Tobacco, Firearms, and Explosives wants to clamp down even more on AP, which it classifies as an explosive.) Barry Lynch, owner of LOC/Precision, a leading mid-range kit maker, says: “I think hybrids are the wave of the future.” After the X-30’s HyperTEK stops passing gas, its pilot Dave Schaefer takes over the radio controls and greases the landing.
The last two days are devoted to experimental rocketry—the homebuilt motors. Composite propellant isn’t particularly difficult to whip up in home labs. But the process demands a substantial amount of time, space, equipment, supplies, patience, and precision. Bob Brown, vice president of Kloudbusters, the Tripoli chapter sponsoring LDRS XXII, explains: “We say that we save money by flying experimental motors, but that’s not true. We spend the same amount of money. We just fly bigger motors.”
Besides being cheaper than their commercial counterparts, experimental motors can be designed to achieve specific goals. “They give you more flexibility,” says Jeff Taylor of Milford, Connecticut, who runs Loki Research and hosts how-to seminars all over the country. “You can tailor the thrust performance to your needs. For higher altitudes, you want a longer burn. For a booster that’s part of a two-stage rocket, you want to accelerate as fast as possible. You can even adjust the color of the flame.” And rocketeers like color, which is why they add sodium to produce an orange flame, strontium for red, magnesium for white, and titanium chips for sparks. “It’s all about fire, smoke, and noise,” Rosenfield says.
Taylor has machined a lot of the hardware that is used in the motor of LDRS’s star attraction, the Aurora. The immaculately finished, 20-foot-tall, carbon-fiber body shrouds sophisticated avionics and telemetry systems, a camera, and the gargantuan P motor, with 1,800 pounds of thrust derived from 50 pounds of Polish Rojo, a wicked homebrew made by motor builder Pat Gordzelik of Canyon, Texas.
The Aurora is the brainchild of Gordzelik and Dan and Terry Stroud, father and son, both of whom live in suburban Dallas. And even though they’ve been planning to fly it for months, the project turns into a last-minute thrash. Work continues until 3:30 a.m. Monday, and the rocket isn’t hauled out on a flatbed trailer to the remote launch pad until after 9 a.m. The FAA waiver is only eight minutes from expiring by the time the launch control officer finally pushes the ignition button.
For what seems to be an eternity, nothing happens. The crew members huddled near the launch pad are deathly silent. The Aurora finally lights, but still the crew says nothing; this is when a CATO is most likely. The rocket launches at a slight angle, and the crew holds its collective breath.
Then the fins right the Aurora’s trajectory, and the rocket arrows straight up at Mach 1.81. The crew is still silent, but now with awe. It isn’t until the rocket is a tiny speck in the sky that the cheering commences. “Oh my God!” Dan Stroud says. “Holy cow! That is awesome!”
The burn lasts 7.81 seconds, and the rocket doesn’t run out of momentum until reaching 29,985 feet. A handful of amateurs have just sent a homemade object five and a half miles into the atmosphere and retrieved it, no worse for the wear, after a 28-minute flight.
“I’m not comfortable calling what we do a hobby,” says Kimberly Harms of Quilcene, Washington, who has her own crew of high-power rocketeers. “A hobby is fun. Well, we don’t come out here in 110-degree heat to fly rockets just for fun. This is a mission.”