HAL5 was largely populated with technical types who longed to escape the stultifying rocket bureaucracy: engineers who wanted to make a difference, idealistic engineering students eager to take what they were learning in school and apply it in the real world. Few of them, however, had Pickens’ special combination of theoretical knowledge and mechanical experience.
It was Pickens who proposed using hybrid rather than solid rocket motors (see “The Right Fuel for the Right Rocket,” p. 62), meaning that the engine would combine liquid and solid propellants. And he suggested using as a fuel asphalt rather than the conventional—but much more expensive and harder to handle—hydroxyl-terminated polybutadiene, or HTPB. The asphalt idea wasn’t new with Pickens; he had gotten it from reading about an eccentric rocket pioneer named Jack Parsons, an early principal at NASA’s Jet Propulsion Laboratory in Pasadena, California, who practiced black magic in his spare time. Eventually Parsons blew himself up while conducting backyard experiments, but not before he had demonstrated that ordinary paving asphalt was a pretty good rocket fuel.
Working on HAL5’s HALO project, an acronym for high-altitude lift-off, Pickens recalls, “I knew that asphalt has a real low heat of vaporization, which means that you can easily heat it a little and get an ignitable vapor. You can pour it, you can cast it, and it’s $17 for 100 pounds. Everybody laughed. I said, ‘Okay, let’s just test it.’ Turned out it had as good a performance as the HTPB. But with the HTPB you had to mix the hardener, you had to do vacuum casting—it was just a pain in the rear.”
Against advice from professional engineers, project director Allison decided to go the hybrid route for the HALO vehicle. “So we were going to use asphalt and laughing gas,” Pickens relates. “We said, ‘We’re going to pave the way to space, and we’re going to laugh all the way.’ ”
Pickens, who ended up in charge of HALO’s propulsion system, assembled the motor from inexpensive components. For the oxidizer tank, he joined two donated aluminum fire extinguisher bottles, neck to neck. Drilling and tapping a hole in the bottom of one tank, he screwed directly into it the motor assembly: a cylinder of hand-wound graphite-epoxy with the fuel “grain” cast inside and the control valve and injectors at one end. The recovery parachute nestled in the depression between the two oxidizer tanks. Avionics and cameras perched on the nose of the rocket, under a conical cap. The rocket, enclosed in a wooden trusswork gondola, was to be carried to 100,000 feet beneath a helium-filled balloon. On firing, it would shoot up through the balloon on its way to space. The launching system—called a rockoon—was an old one that had been used for scientific sounding rockets in the early 1950s. Pickens nicknamed the team the “rockoon buffoons.”
He built test stands and associated equipment, and would eventually log more than 300 static firings of the HALO motor. In March 1997, the group launched its rockoon from a beach in North Carolina. Unfortunately, the balloon split open before reaching its peak altitude, and the rocket, hastily fired from a vertical position as it fell, attained an altitude later calculated to have been 36 miles. As often happens with rocket development, the failure had its up side. The HALO rockoon reached the highest altitude ever for an amateur-built rocket, earning it an entry in the Guinness Book of Records.
A year earlier, Allison and Pickens had founded the High Altitude Research Corporation, and one of its early projects was to go after the CATS (Cheap Access To Space) prize, offered by the Space Frontier Foundation for the first amateur-built rocket to lift a two-kilogram (4.5-pound) payload to an altitude of 200 kilometers (124 miles). The team’s entry—“HALO on steroids,” Allison calls it—blew itself apart 100,000 feet over the Gulf of Mexico in 2000, only days before the $250,000 CATS prize expired unclaimed.
It wasn’t long, though, before Pickens had another project to work on, for even higher stakes.
In 1999, Burt Rutan, who had launched his aeronautical engineering career 25 years earlier with an arresting series of canard designs for amateur airplane builders, came to Huntsville to speak to a chapter of the Experimental Aircraft Association. The visit had an ulterior motive; Rutan was scouting companies involved in rocket propulsion because he wanted to compete for the X Prize, a $10 million award awaiting anyone who could launch a reusable passenger vehicle into space twice within two weeks.
“You know, I’m getting bored with flying,” Pickens recalls Rutan announcing to the homebuilders (which must have been like Jesus saying to the apostles, “I’m getting tired of religion”).
“I’m really thinking about rocketships,” Rutan said. “I’ve looked at solid [fuel]s, I’ve looked at liquids, I’m looking at all options. If there are any rocket people out there who can steer me….” Rutan had been talking to the big players in industry—Aerojet and Thiokol—and both had offered existing engines. They even offered to send out guys in spacesuits to fuel it. “Spacesuits?” Rutan said. “We’re not even going to have spacesuits inside the ship!”