1 Jet Engine & 18,000 Pounds of Fuel

With the rutan-designed globalflyer, these adventurers tackle "the first great aviation challenge of the new century." Technology: cutting-edge. Risks: gigantic.
_GlobalFlyer might go nonstop around the world, a feat Voyager accomplished in 1986. But that's where the similarities end. With new aerodynamics, materials and design, Burt Rutan's new craft is significantly more sophisticated than the old record breaker. Aerodynamics: The GlobalFlyer team is using advanced computer technology--specifically, computational fluid dynamics--to vastly reduce the airplane's drag and optimize the structure for long-range, exceptionally high-fuel-load flying. Materials: The thousands of pounds of fuel in Voyager's four-section wings made them droop down to the runway, where they scraped against the ground during takeoff. In order to avoid the same problem, GlobalFlyer's wings are constructed of a single 100-foot-long piece of reinforced composite. Design: Without horizontal tails to stabilize it, Voyager flexed and twisted in ways that made it hard to control. GlobalFlyer has complete tail assemblies, which dampen unwanted up-and-down movement._ John Macneill

“Around the world in 80 hours.” The happy marketing slogan affixed to Steve Fossett’s attempt to set a nonstop, around-the-world solo flight record makes it sound like something of a nostalgic lark: Hints of Jules Verne, the golden age of global adventure. And indeed, if all goes well, sometime later this year Fossett will complete a circumnavigation of the globe, pass over America’s Pacific shore, point his wide, spindly airplane–called the Virgin Atlantic GlobalFlyer–over the Rocky Mountains, and line up on the same Midwestern runway he left 21,000 miles and 80 hours before. Awake for essentially the entire flight, he will have been battered by turbulence and the mental strain of relentless engine monitoring, fuel management, weather analysis and navigation–to say nothing of actual flying.

That’s if things go well. If things do not go well, Fossett’s flight will end in a horrific fireball during the incredibly dangerous takeoff of the fuel-pregnant, exquisitely stressed aircraft. Or his distinctly sci-fi-looking airplane–it has a trimaran-like configuration with a single jet engine poised inches above the cockpit’s tiny bubble canopy–will disintegrate in turbulence or high-G emergency maneuvering. Or Fossett, despite experience and training, will simply fall asleep. “If he becomes incapacitated–if he falls asleep and doesn’t wake up–there will be an accident,” says Burt Rutan, the famed aerospace designer who created GlobalFlyer. “There’s no autoland capability and no way of controlling the airplane from outside the cockpit.”

This is, in other words, a delightfully dangerous undertaking. The airplane is a flying fuel tank that must remain controllable in buffeting winds at high altitude while it burns through 82 percent of its weight. But Fossett is confident. For starters, the 59-year-old businessman, who made his fortune as an investment banker and his fame as an adventurer, has done this kind of thing before. His nautical and aviation records include the first nonstop solo flight around the world in a balloon, which he achieved in 2002 on his sixth try. (He is also currently shooting for a glider altitude record of 62,000 feet, and on Nov 14 in Argentina set a glider distance record of 1,244 miles.) His partner in adventure, Sir Richard Branson, the swashbuckling founder, CEO and chairman of project-sponsor Virgin Atlantic, is an old ballooning buddy with world records of his own–and will serve as Fossett’s reserve pilot. And Fossett can place a lot of faith in his aircraft and the man who designed it: After all, Burt Rutan built the historic, prop-driven Voyager airplane, which his brother, Dick Rutan, and Jeana Yeager flew on a nine-day around-the-world unrefueled flight in 1986.

THE TECHNOLOGY. GlobalFlyer represents a bigger technical challenge than even Voyager did. The latter airplane, which now hangs in the Smithsonian’s National Air and Space Museum, flew with two piston engines, carried 7,000 pounds of fuel, and had two pilots. GlobalFlyer will sprint where Voyager strolled, and its design pushes weight-reduction and structural-integrity technology to the absolute limits. (The fuel tanks in the twin outboard booms are informally referred to as watermelons–not the most reassuring analogy.) With 18,000 pounds of military jet fuel onboard, takeoff will be a white-knuckle affair; toward the end of the flight, with most of the fuel spent, the airplane will be feather-light and especially susceptible to turbulence.

GlobalFlyer is now in the late stages of fabrication at Rutan’s famous airplane factory, Scaled Composites, in the high desert of Mojave, California. Directly across the runway from Scaled and its neighbors, a collection of civilian flight-test companies, sit dozens of grounded passenger jets, their windows draped in reflective foil, waiting for the airline industry to recover from its slump.

But things are hopping at Scaled. In one hangar, employees test equipment for what could become the world’s first successful private manned space program–a project called Tier One that is funded by Microsoft billionaire Paul Allen’s investment firm, Vulcan. (The project, which uses a mothership aircraft to launch a smaller rocket-propelled winged vehicle, is intended to prove the viability of commercial suborbital spaceflights (see “Burt Builds Your Ride to Space,” July ’03).) Other hangars contain secret projects with clients that Rutan won’t dentify–often contractors to the U.S. military. GlobalFlyer, too, was a secret from its inception three years ago until a press conference on October 23 in London–and Popular Science is the first to be shown the exceptionally sophisticated airplane in the making.

In a hangar that had to be stretched to accommodate GlobalFlyer‘s 114-foot wingspan (the builders had to knock out a wall into a nearby office so one wing could poke through), team members work to complete the airplane for the commencement of the flight-test program (the first test flight will likely be in the early months of 2004). They huddle around the booms, each of which has its own tail assembly, and the central fuselage, installing flight controls and avionics, tinkering with the Williams FJ44-3 turbofan engine, and draping strips of epoxy-soaked carbon-fiber fabric over joints in the fuselage structure.

There are wing and fuselage ribs in GlobalFlyer, but far fewer than in a conventional aircraft. For the most part the composite skin is the structure. “The ribs serve to stabilize the skins, which are the primary load-carrying members,” explains Jon Karkow, the project’s soft-spoken lead engineer. “A carbon- fiber spar, shaped like an I-beam, resists the huge wing-bending loads.” Karkow shows off two examples of the composite material, a piece about a quarter-inch thick for the wings and a 3/8-inch-thick piece for the fuselage. A sandwich of carbon fiber, honeycomb and another carbon surface, the composite is substantially stronger and lighter–and pricier, and harder to manufacture–than most aircraft metals. Walking around to the ailerons on the wing, Karkow points out that there is almost no metal; even the control surfaces are connected to the airplane with composite hinges. The only metal structural components (engine and avionics not included) are the aluminum landing-gear struts and the engine mount.

Fabrication began in September 2002, after a two-year design process during which Rutan and his lead engineers determined the airplane’s configuration; this was done in collaboration with Fossett, who commissioned the airplane from Scaled after discussing the flight with both Rutan brothers. “When Steve came to us, he didn’t ask for a turbofan–he wanted to do a single-place Voyager,” Burt Rutan recalls, adding that the original Voyager configuration was chosen partially because at the time they didn’t think they could get the range out of a jet engine, which consumes much more fuel than piston engines. “But I told him I wouldn’t do a piston engine–I’ve already done it.”

The fundamental challenge was high fuel fraction: the percentage of the total weight of the aircraft represented by the fuel. Rutan took a weekend and figured out that based on experience in the competition to build the Global Hawk unmanned aerial vehicle, which had incredibly high fuel-fraction requirements, he might be able to make a jet-engine aircraft work. It would require pushing the aerodynamics much further than he did with Voyager in order to decrease drag and improve efficiency, and extreme reductions in structural weight. GlobalFlyer would have to carry three times more fuel than Voyager did because of the turbofan’s thirst. Even with that much fuel, its range would be shorter than that of Voyager, and this forced Rutan to propose that the new aircraft follow the jet stream around the world to take advantage of a 50-to-100-knot boost. A route along the Tropic of Capricorn instead of the equator would shave off miles while still qualifying the flight for the record, whose parameters are rigidly defined by the Fdration Aronautique Internationale. (The airplane was originally called Capricorn. When Richard Branson joined the team in mid-2003 as a sponsor, he won the right to rename it.)

“So I went to Steve and said that I can make an autopilot that weighs less than Jeana (Yeager), and having one engine instead of two will buy us some more weight,” Rutan says. “I know we can get a fuel fraction of 82 percent.” (Voyager’s was 72 percent.)

Fossett liked the plan, and the real design work began, with aerodynamicist John Roncz designing the airfoils (the wing shapes–Roncz also did Voyager’s), Joe Ruddy working on the structure, Chuck Coleman on the systems, and Bob Morgan on the landing gear. Along the way, Karkow says, the team experimented with several configurations. They tried removing the fuselage altogether and putting the pilot in one of the booms, but that caused aerodynamic problems that reduced range and affected performance in other ways. They considered a more conventional shape but decided that the jet stream route favored the aerodynamics of the trimaran configuration– it’s the design that best permitted long-range flight at high altitude with a fast tailwind. Then the trimaran design was tweaked. “It’s an iterative process,” Karkow explains. “We gradually narrowed in on what you see here. As our fuel estimates changed, for example, the booms got alternately longer and shorter. We moved things around for visibility and to fine-tune the center of gravity.”

GlobalFlyer‘s aerodynamics benefit from modern computing power, which allows engineers to study a design using computational fluid dynamics–putting a digital airplane in a digital wind-tunnel. “When I designed Voyager,” Rutan says, “I did it on an Apple II with 48K of memory, and I wrote my own Basic program. Now we have the same state-of-the-art CFD as the big companies. We’re now very smart at designing low-drag airplanes.”

Smoother aerodynamics will buy Fossett a lot of miles, but not enough to get back to his departure airport. (This location is still to be determined, but will most likely be someplace in the Midwest, so if he does run out of fuel, it won’t be over water.) Weight is the fundamental issue–and it’s for that reason that GlobalFlyer is entirely composite-built, and as simple as can be. All the components that weren’t deemed critical were deleted. There are only a few inspection panels to reach internal components, for example; if you need to get inside elsewhere, you get out a saw and then patch the hole later with carbon fiber. There are no handles on the cockpit door. “We don’t have the luxury of a fancy door handle,” Karkow says. “It’s a plug-style door, so pressure will hold it against the seal. If we need to get inside in an emergency, we’ll just kick it in–there won’t be any pressure on the ground.”

There are echoes here of Charles Lindbergh’s 1927 solo flight across the Atlantic. Lindbergh chose not to carry a life raft,
parachute or radio because he didn’t think he’d need them. He presumed success, and rafts and such simply added dangerous weight. Fossett will have those things, but only because they’re substantially lighter than they were in 1927. But he won’t have a fire-detection-and-extinguishing system, de-icing equipment or a backup landing-gear-extension system–all too heavy.

THE FLIGHT. Empty, GlobalFlyer weighs 3,577 pounds. Fully fueled, it will come in at 22,066 pounds. With all that weight, and a single business-jet engine pushing it along, it will take Fossett 14 hours to reach his cruise altitude of 45,000 feet.

By then, Rutan and his team will have done their part. The rest will be up to Fossett. As time wears on, his mental edge will be harder to maintain. Fossett will have an autopilot but will still have to fly and monitor the mission. As with Lindbergh, that will likely help him stay alert. “I’ll be taking good care of fluids and my basic physical considerations,” says Fossett, who runs daily and once swam the English Channel, “and I will be fully occupied with navigation and flight controls. I’ll be in active communication with mission control by satellite e-mail and telephone. We’ll probably also carry a scientific experiment. With sailing and balloons, I’ve remained at controls for those kinds of times before.”

Still, no one can predict what Fossett’s mental state will be in the last legs of the flight; history, though, offers much to contemplate. By only the 17th hour of his 33-hour transatlantic flight, Lindbergh–who hadn’t slept the night before–was physically exhausted, hallucinating vividly, and experiencing uncontrollable 30-second “microsleeps”; he had lost control of his eyelids and was beginning to experience what can best be described as a complete mental detachment from his body and his environment. It was only his exceptional skills as an aviator that kept his Spirit of St. Louis on course.

Contemporary pilots don’t have it much easier: B-2 bomber pilots are often just barely able to manage their missions–which in some cases last more than 40 hours–despite the fact that they fly in pairs and keep a lawn chair in the cockpit to stretch out on. Dick Rutan and Jeana Yeager found that the hardest part of their around-the-world record was simply managing the physical torture of nine days in a cockpit the size of a sofa.

Burt Rutan has his own catalog of worries: “I’m concerned that the airplane will be difficult to fly, difficult to come down and put on end of runway,” he says. “We have drogue chutes to slow it down, but those are risky.” They might also need rockets to assist with the takeoff roll, and Rutan says there are still some very big questions about whether the airplane has enough range. Turbulence on takeoff will be a huge problem, as will tuning the autopilot to work at GlobalFlyer‘s heaviest weight through its lightest.

But these are the challenges the team craves–to make machine and strategy come together for a mission that hovers between audacious and preposterous. “This is a wonderful challenge to get involved in,” Branson says with typical exuberance, “particularly in a year when we’ve lost Concorde forever–it’s a positive thing and will be the first major accomplishment in the second century of aviation.” Karkow concurs: “This is one of the most fun projects I’ve done here. It’s a contest against Mother Nature. There’s a concrete goal we’re trying to achieve. With other programs the goals are more fuzzy–general research, future production–but this is in-your-face.”

It’s not inappropriate to liken the boldness of this attempt to Lindbergh’s quest. “This will be a milestone in aviation,” Fossett says. “It will test not only the state of airplane technology–all-composite structures, highly efficient jet engines–but also be a pure test of pilot performance.” But for all the danger, the GlobalFlyer adventure has little of the momentousness of Lindbergh’s flight. In 1927 there was a worldwide obsession with airplanes, and transatlantic flights were considered an economically crucial next step. Although the GlobalFlyer program will ostensibly demonstrate long-range flight technologies, Rutan isn’t much interested in freighting the project with claims about import. Last August, while discussing his SpaceShipOne program before a standing-room-only crowd at the Experimental Aircraft Association’s annual gathering in Oshkosh, Wisconsin, he gleefully dismissed any argument that his program would contribute to any body of knowledge whatsoever. “What scientific value will this program have?” he asked. His answer, shouted into a microphone: “We don’t care! We’re doing this for one reason only: fun.”