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.