By the time Neil Armstrong walked on the moon in July 1969, two rocket scientists--Gary Hudson, a college dropout, and George Mueller, perhaps the most respected engineer of his generation--already knew that something radical had to be done about the way we get ourselves into space.

Will the Roton win the new space race? A technician scrambles to finish a test vehicle set to fly this spring. At top, Rotary Rocket founders Bevan McKinney (left) and Gary Hudson pin their hopes on a contraption with 72 small thrusters (one is at center-left) and rocket-powered helicopter blades (at bottom).

The problem is a mean trick of physics called the rocket equation. Every rocket engineer learns about the rocket equation—first to love it, then to hate it, eventually to accept it. The equation tells you how much fuel your rocket needs to pry itself from the claws of gravity. The premise is deceptively simple: the heavier the rocket or its payload, the more fuel it takes to reach orbit. But fuel is heavy; so when you plug the weight of the fuel into the rocket equation, you find that you have to add even more fuel. Adding fuel means building a bigger tank, which makes the rocket heavier, which means more fuel. And so on. 

The rocket equation first became a serious nuisance during the race to the moon. Engineers came up with a stopgap solution: rockets with several stages. Jettisoning each stage as it used up fuel reduced the total weight of the capsule that ultimately went into orbit, but some pretty expensive hardware got dumped into the ocean in the process. Hudson and Mueller wondered if it was possible to build a single-stage rocket that could be used over and over again. Would the rocket equation allow it?

The two men didn’t know each other, but they were of one mind. If somebody could build a rocket that could be refueled again and again and again, a beat-up space-going pickup truck, it would change everything. Space would no longer be the province of government bureaucracies and gold-plated aerospace contracts. Small companies, even guys like Hudson and Mueller, could scrape together enough money to get into orbit. And that would open up the solar system to manned exploration. Because once you’ve climbed beyond reach of Earth’s gravity, to paraphrase Robert Heinlein, it doesn’t take a whole lot more fuel to get just about anywhere out there.

Neither Hudson nor Mueller quite realized that they were hearing a siren’s call, or that it would be three decades before they finally got their chance to beat the rocket equation.

Hudson took his first few steps on the path to his destiny when he realized that he was bored with the countless picayune mind-numbing details that make up the discipline of engineering. And he had become so taken with the idea of a reusable rocket that he dropped out of college to build one.

AIRPLANE ON THE EDGE

Stephen Wurst learned an important lesson while trying to build the ill-fated National Aero-Space Plane. It was intended to whisk passengers from New York to Tokyo in the time it takes to drive to the airport. But it required speeds of Mach 20 or more, which turned out to be quite an expensive concept. “People in the commercial sector aren’t interested in new technology,” says Wurst. “They want to know how much it will cost.”

In 1994, shortly after the project fizzled, Wurst founded Space Access L.L.C. in Palmdale, California, with the aim of designing a less technically ambitious vehicle that can loft satellites into orbit. Rather than use rocket engines, which have to lug their own oxygen, Wurst wants to use a ramjet, a sort of super jet engine commonly used on planes that travel three or more times the speed of sound. Like jet engines, ramjets mix and compress incoming air with fuel, but they do so with a clever geometric design rather than with huge compressor blades. Because they have no moving parts, they’re more reliable than jet engines.

The problem is, without blades to suck air, they’re useless when the plane is moving slower than about 1,200 miles per hour. Wurst and his colleages, however, managed to find a way to force air and fuel into the jet at great pressure, simulating the ramjet effect even at rest. “I told my team, ‘Go make this work at low speeds,’” Wurst says. “It’s not very exotic to tell people to make something that goes fast go slow, but it’s the sort of problem a commercial endeavor can handle. The hard part was already done.”

Wurst’s idea is to mate the engine with a new airplane design, take the craft up to an altitude of about 30 miles, at which point the ramjets can no longer be used, coast to an altitude of 60 miles, then release the satellite payload with a small conventional rocket attached. The space plane will land on a runway, while the rocket, after delivering its payload, will fly back to the ground like the space shuttle. Wurst has one big problem: he has managed to raise only a tiny fraction of the “hundreds of millions” of dollars he says he’ll need to build a prototype. But he remains confident he’ll deliver satellites into orbit by 2003.—Jeffrey Winters

Ten years later he had found a wealthy Texan to bankroll a conventional multistage rocket. It wasn’t reusable, but it was cheap, and Hudson, 30 years old, had to take what he could get. It took him and his team of engineers seven months to build it and less than seven seconds to blow it up. The problem was a stuck valve. The person who was supposed to monitor the valve had been busy taking photographs.

For a long time it seemed as though that might be the end of the story. But as luck would have it, the cold war ended and the economy was on a roll. In 1990, Motorola unveiled plans to put up its Iridium network of 66 satellites to beam signals to handheld gadgets like cell phones anywhere on the globe, and several other firms quickly followed. Suddenly, thousands of satellites were sitting around in crates waiting for a ride to low Earth orbit. The bull market of the century sent venture capitalists scurrying around for upstart companies that could build cheap rockets.

Suddenly, a lot of satellites were waiting for a ride into orbit

Meanwhile, Hudson had taken a job as a consultant for, among other firms, Kistler Aerospace of Kirkland, Washington. Working at Kistler was bittersweet. The firm was building his dream, a single-stage reusable rocket called the K0. Hudson had been hired to work on propulsion systems.

At Kistler, Hudson met another consulting engineer, Bevan McKinney, who had his own ideas about reusable rockets. They hit it off and in 1996 formed Rotary Rocket. They managed to raise several million dollars from two individuals, one of which was novelist Tom Clancy. Before long they had enough money to throw up some tin-roofed buildings in the Mojave Desert and start building a rocket.

Mojave Airport begins just two blocks behind a strip of fast-food restaurants and gas stations along Route 14, but it seems to extend indefinitely into the broad desert valley. There among the Joshua trees and tumbleweed, old Boeing 727s sit on blocks waiting to be stripped for spare parts. According to a billboard at the edge of town, Mojave is also “home of the Voyager,” the incredibly light airplane designed by Burt Rutan that set a record by becoming the first single-engine airplane to fly around the world nonstop. Rutan’s firm, Scaled Composites, builds odd-looking contraptions like the Vari-eze that pilots find delightful to fly. Scaled Composites is building Hudson’s rocket, the Roton. Though not finished, the Roton looks a lot like a 63-foot-inverted plastic ice-cream cone: fat at the bottom, tapering slightly to a blunt nose cone.

George Mueller wanted the space shuttle to be dirt cheap and fully reusable. The Kistler K1 may fulfill his dream.

One of the key reasons Hudson believes the time is ripe for a reusable rocket is the availability of extremely light, extremely rigid materials loosely termed composites, which means combinations of different materials, in this case not ordinary forms of foam and plastic. The plastic comes in sheets with reinforcing carbon fibers woven in a particular way that gives them properties of lightness, strength and resistance to heat. The method that Scaled Composites technicians use to make the structures doesn’t seem very techie. First, they take a huge block of ordinary Styrofoam and hollow it out into the shape they want the structure to be, like a mold. Then they lay down a sheet of plastic. Then they glue on a sheet of foam. Then they glue on a sheet of plastic. That makes a panel. Piece together a bunch of panels just so, and the resulting structure is impossibly rigid.

Hudson takes pride in his low-budget approach to rocket building, but it’s tinged with consciousness of past failures. “I was once introduced to a NASA engineer at a party as the guy who blows up rockets but takes only 25 people to do it, as opposed to 25,000,” Hudson says. “I could take off my shirt and show you where the arrows are. But it means we actually have a better chance to pull this off than probably anybody else. We’ve learned from the mistakes we’ve made, and we’ve made many.”

Unlike his earlier ventures, this project is one on which Hudson has concentrated mainly on the big picture, leaving his partner, Bevin McKinney, to the details. “At a detailed level, I wouldn’t earn my keep at an aerospace company,” he says. “At the level of an intuitive engineer, at a systems level, I’m pretty good. Bevin’s a much better engineer than I, but I’m the guy who says, ‘Why don’t we do it this way?’ And I push. I push the whole company in a direction. Fifty percent of the time I’m dead wrong, and sometimes people get frustrated. But you learn from those mistakes.”

McKinney provided the original idea for the Roton. For years he had been mulling over a design that combined the characteristics of a helicopter and a conventional rocket. Some experimental reentry vehicles were built back in the 1960s and 1970s that used rotating blades to slow them down from supersonic speeds. But McKinney added the notion of powering the blades with a tiny rocket engine mounted on the tip of each blade.

 Hudson, however, insisted that the Roton carry pilots—two of them—in addition to a payload large enough for communications satellites, which will be Roton’s bread and butter. Hudson believes that people will have a big role in space, even in such mundane tasks as maintaining satellites, and that an ability to carry people is a key to Roton’s long-term usefulness.

‘Okay, so we’re doing some sporty with the engines’

A few months into the project, however, it became clear that helicopter blades wouldn’t be able to generate enough thrust to carry both a two-person crew and a three-ton communications satellite. “As soon as we started sizing the thing up, we were concerned,” Hudson says. “It wasn’t that the technology wasn’t there, but the development risk was growing.” He and McKinney decided to scrap the idea of lifting off with blades. Instead, the Roton would go up under rocket power with its blades folded down to the sides. Upon reentering the atmosphere, the blades would unfold and whirl around, creating drag and slowing the ship down. The little rockets on the blades’ tips would fire just as the ship neared the ground, slowing its descent for a gentle landing. The scheme has the advantage of allowing Hudson and McKinney to use conventional helicopter rotors. 





Kistler Aerospace
Rotary Rocket
Space Entrepeneur Weblinks from the Discovery Channel