In the spring of 1997, Vern Raburn, a technology executive and recreational pilot, took Microsoft co-founder Paul Allen to a dusty landing strip in the Mojave Desert. Raburn had been an early Microsoft employee, and he was now working for ­Allen, helping the billionaire invest his fortune. The pair had flown in on Allen’s Boeing 757 from Seattle to meet storied aircraft designer Burt Rutan. He was working on concepts that had commercial potential, and Raburn wanted his boss to have a look. Seated in a conference room overlooking the runway, Rutan presented his designs to the two visitors, including his latest idea: a civilian rocket he believed would herald the age of space tourism. Rutan would need an angel investor, and Allen, an amateur space geek himself, liked what he saw.

After the presentation, Rutan brought the two men to a nearby hangar, where he was assembling another prototype, something called the V-Jet II—a four-seat jet created by Williams International that was smaller than a Ford Explorer and capable of flying faster than 300 miles per hour. The V-Jet was powered by a pair of new engines—the tiny motors weighed just 85 pounds each, yet they could produce more than 700 pounds of thrust. Rutan told his visitors that swarms of these affordable mini-jets could be used for personal travel and as air taxis, shuttling fliers to little-used municipal airports.

Raburn was hooked instantly. “I got really excited,” he recently recalled. “I tried to sell Paul on the idea.” But Allen balked. The personal computer, yes; a personal jet, what’s the point? Allen, who owned two Boeings and a Gulfstream, thought private planes were a luxury for billionaires, not the masses. After all, Warren Buffett called his jet the Indefensible.

Allen invested $20 million in Rutan’s rocket several years later, but spent not a penny on the mini-jet. A few months after meeting with Rutan, Raburn decided that if no one else would finance and build the V-Jet, he’d do it himself.

It’s June 2007. Raburn and I bounce 16,000 feet above the broad mesas of the New Mexican desert in the successor to the V-Jet, which he has christened the Eclipse 500. He fiddles with the autopilot as blasts of summer air shake the cabin. The auto­pilot refuses to engage, which forces Raburn to take control. “This sucker is so easy to fly,” he says, guiding the Eclipse into a wide arc. Below, the modest Albuquerque skyline slides past.

Albuquerque gave birth to the personal-computer revolution—Bill Gates launched Microsoft from a hotel room here in 1975. A few years later, Raburn went to work for Gates as Microsoft’s 18th employee, but he left in 1982 and sold his options before the stock’s meteoric rise. Today his 5 percent stake would be worth billions, but that doesn’t bother Raburn. “Money never motivated me,” he says. “I’ve made more money than most people ever dream about making. I’ve also lost more money than most people dream about losing.”

Raburn looks through the cockpit window toward the arched roof of an old TWA hangar that is now the main factory for his company, Eclipse Aviation. Inside, the 1960s interior has been given a 21st-century makeover. Technicians clad in navy-blue coveralls crawl over the sleek skeletons of Eclipse 500s being readied for flight. Tangled wires dangle like entrails from the disemboweled fuselages. Though the assembly floor hums with activity, the normal cacophony of industry—hammering and welding—is eerily absent. Taking a cue from PC-maker Dell, Eclipse doesn’t manufacture anything: Parts are flown in from 85 suppliers around the world and assembled like life-size Lego models, using a technique known as friction stir welding, which requires no rivets. Raburn says Eclipse could get a jet from the factory to the runway in only four and a half days. Conventional aircraft construction takes three months. But so far, Eclipse has needed 30 days because of manufacturing inefficiencies, supplier delays, and ongoing design changes.

The Eclipse 500 is a scant 33.7 feet long and costs $1.5 mil­lion, a bargain for a private jet. (The cheapest jet on the market now goes for $2.25 million.) It has a sensuous, conical nose, stubby wings, and a T-shaped tail flanked by two trash-can-size turbine engines. Sitting on the tarmac, it looks like a Gulfstream that has been shrunk in the dryer. Inside the cockpit, the traditional dials and gauges have been replaced with a trio of large computer screens; a videogame-like joystick takes the place of the pilot’s control wheel. The Eclipse can reach an altitude of 41,000 feet and can fly at 400 m.p.h. for three hours or so. Sitting in its leather interior is like jumping into the passenger seat of a Lexus.

Since forming Eclipse Aviation in 1998, Raburn has raised close to $1 billion in private financing from investors, including Bill Gates, biotech billionaire Alfred Mann, and UBS, the Swiss investment bank. His utopian vision of affordable jet travel has inspired nearly a dozen companies—including industry giant Cessna, Brazilian aircraft maker Embraer, and even Honda—to develop models of their own, creating an entirely new category of plane known as very light jets, or V.L.J.’s. Raburn’s acolytes see him as an aviation pioneer equal to Howard Hughes.

But Hughes’ most ambitious design ultimately flopped, and Raburn risks a similar fate. The Eclipse 500 is three years behind schedule, and it will be several years before the assembly line churns out the three planes a day that Raburn has predicted. In June, he skirted financial ruin when a deal for $200 million in financing imploded the night before it was to close, forcing him to scramble to secure new funds. “The company was nearly destroyed,” he says wanly.

Raburn’s critics—and he has many—say he is a dilettante, a pariah, a Silicon Valley refugee who naively believes airplanes can be snapped together like computers. His detractors also lampoon his public pronouncements about the Eclipse’s revolutionary potential, and they snipe over the investment bubble in mini-jets that has gripped the aviation industry. Foes derisively refer to the Eclipse as a “dotcom with wings.”

Raburn—who, at 57 years old, has a boyish face, a stocky frame, and a short temper—clearly enjoys a dogfight. Back on the ground, he says, “This industry has been screwing customers for decades, and I’ve been very disdainful of that.” He wears a golf shirt and charcoal slacks and sips coffee from a mug ringed with block letters: "I love the smell of jet fuel in the morning." He offers another explanation for his legion of enemies. “I guess I’m the world’s biggest asshole.”

Growing up in rural Oklahoma, Raburn watched the sun glint off silver specks inching across the horizon and dreamed of flying. “Everybody ends up with something in life. For me it became the sky,” he says. “Being an obsessive son of a bitch, it didn’t matter what I did, as long as it dealt with airplanes.” His father was an engineer at Douglas Aircraft, and Vern studied aeronautics at California Polytechnic. By the time of his graduation in 1968, however, the aerospace industry was on the verge of a nosedive. Raburn went on to work for Gates before becoming general manager of Lotus Development, C.E.O. of Symantec, and president of the Paul Allen Group (now Vulcan Inc.).

Having earned his pilot’s license at 17, Raburn became an avid aviator, spending more than 6,500 hours aloft and learning to fly 30 types of airplanes. In the 1990s, while scouting investment prospects for ­Allen, Raburn flew around the country for two weeks every month in a six-seat Cessna that cost about $3 million, then the cheapest private jet in the sky. He sat on the boards of 13 companies, and jetting between Seattle and places like Ithaca, New York, showed him “what a marvelous gift of time a jet can produce.” After Raburn left Vulcan, he sought out Sam Williams, the brilliant and secretive engineer, now 86 years old, who had built the engines for the V-Jet. A standard commercial-jet ­engine has about 6,000 parts; Williams, who is legally blind, figured out how to make a smaller turbine with only 600. The pair agreed to go into business to commercialize the V-Jet, and Raburn set out to raise money for the venture. He initially called the company Pronto Aircraft but changed the name after an employee’s friend said his design would “eclipse” all his competitors. As a veteran of the technology world, Raburn knew every major financier—John ­Doerr was an usher at his wedding—and he made the rounds of Silicon Valley venture capital outfits. This was at the height of the in­ternet bubble, and investors on Sand Hill Road were dazzled by e‑commerce and weren’t interested in an old economy dinosaur like aerospace. Luckily, Raburn’s former boss Bill Gates put up $20 million in seed capital, according to an investor.

In May 2000, about 150 eager customers began lining up as early as 2 a.m. in front of the airport Hilton in Phoenix, holding $155,000 checks. Later that morning, Raburn unveiled the design for the Eclipse 500. It had matured from Rutan’s original V-Jet—expanding to six seats and sporting an aluminum body in place of the V-Jet’s carbon-fiber shell—but was priced at just $775,000. Raburn electrified his audience. The pilots rushed the stage to hand over their deposits for the first Eclipses, which Raburn told them would be rolling off the Albuquerque assembly line by 2003.

Many of Raburn’s competitors remain skeptical. “I’ve heard comments that [Eclipse] is a game changer. I’ve never heard supporting dialogue on what rules are changing,” Jack Pelton, Cessna’s C.E.O., says. The year Raburn unveiled his Eclipse, the market for private planes was just climbing out of a ­depression. At its peak in 1978, the industry shipped 17,811 ­civilian airplanes manufactured in the U.S. By 1994, the number had plummeted to 928. The Federal Aviation Administration’s strict safety regulations, coupled with punitive liability-­insurance claims, steered aircraft companies toward cautious designs. No one could understand how Raburn’s business model would work. Last year, the aviation industry produced only about 1,000 private jets, and Raburn has boasted about mass-producing thousands of Eclipses.

“The Eclipse’s impossibly low price depends on the impossibly high production rates,” says Richard Aboulafia, an aviation analyst with the Teal Group. “I’ve never seen so much hocus-pocus in this industry." Raburn’s success in the computer business impresses no one. “If your computer crashes, no one gets hurt,” says Matt Huff, vice president for business development at Williams International. "Here, if something goes wrong, people can die."
On a cloudless morning in August 2002, the first Eclipse 500 taxied onto a runway at Albuquerque’s international airport and revved its two Williams engines to full throttle. As the plane bounced down the centerline at 90 m.p.h., its wings gripped the air and, in seconds, Raburn’s dream smoothly took flight. The test pilot put the Eclipse 500 through modest turns and rolls and, 60 minutes later, brought the plane down for a safe landing.

The thrill of the Eclipse’s maiden flight would be fleeting, however. Days later, the temperamental engines malfunctioned, and by November, Raburn’s partnership with Williams had dissolved in a flurry of bitter ­recriminations. “Williams International lied through its teeth about the [development] schedule, and so we were faced with a huge delay,” Raburn says. Williams International acknowledges that the engines were behind schedule but denies making any misrepresentations.

With no engines and little cash on hand, Raburn was grounded and forced to cancel a round of financing. By the winter of 2002, Pratt & Whitney Canada, a well-respected engine manufacturer, had built a scaled-down jet engine that could fit on the Eclipse. Raburn liked Pratt’s design but desperately needed cash to get his plane back in the air once he signed the contract. Fortunately, he still had the goodwill of his investors; according to one of them, Mann led another round of financing with $50 million.

The engine problems pushed Raburn’s delivery date back two years. And development continued to go badly. In October 2006, after the F.A.A. certified the Eclipse 500 for flight, a group of F.A.A. engineers filed a grievance with the agency. “We’re concerned that the Eclipse project got rushed and managers ended up getting bonuses on that project,” said Tomaso DiPaolo, the engineers’ union representative, adding that the Eclipse is “safe as long as it’s grounded, I suppose.”

An F.A.A. spokesperson says the agency stands by its certification but acknowledges that the Department of Transportation’s inspector general was assigned to investigate the union’s complaint. Raburn bristles at the engineers’ red flag. “There’s a fair amount of bullshit in this complaint that is based on ego,” he says. “If the airplane is as unsafe as they claim it is, it would have been falling out of the sky by now.”

Every new aircraft design struggles early on, of course, but a vexing series of new problems has cropped up for Raburn. Eclipse’s partnership with Avidyne—the Massachusetts-based company that designed the plane’s cockpit displays—collapsed, and the electronics replacement won’t be complete for six months. This spring, Eclipse discovered that the cockpit windows were cracking, requiring engineers to double the number of fasteners to hold the glass in place. And the company’s pilot-training program is behind schedule.

Even Raburn admits he has a pattern of overpromising and underdelivering. “We clearly stumbled,” he says, but “unlike some other companies, we’ll admit it when we screw up.” At a trade show last October, he brazenly declared he would deliver 500 Eclipses this year; by mid-June, only 30 planes had limped off the assembly line. This spring, Raburn hired Todd ­Fierro, an 18-year veteran of Ford Motor, to overhaul Eclipse’s ­assembly line. But some wonder if these fixes can stave off crisis, especially since the market for V.L.J.’s has become very crowded. “There is a bubble in the market, and there will be a shakeout,” says Gerald Bernstein, an aviation analyst with the Velocity Group.

A thin strip of concrete appears beyond the Eclipse’s nose. We are descending at 100 m.p.h., and the Albuquerque airport’s runway is rapidly filling the cockpit windows. “I’m amazed at how fast this plane can slow down,” Raburn says, a comforting observation, since we’re about to hit the ground. He flips a switch, and the landing gear extends with a resounding clunk, followed shortly by the screech of rubber meeting runway. Raburn applies the brakes and pulls the Eclipse 500 to a stop in front of his headquarters. We alight from the cabin as a Southwest Airlines 737 roars by, its massive engines sending tremors across the tarmac. I glance over at the Eclipse. In comparison to the Boeing, it looks cute, like a child’s toy.

“That was fun, wasn’t it?” Raburn says. He breaks into a broad grin and steals one final look at his plane as we walk to his office. He hadn’t flown an Eclipse 500 in three months, and the experience was clearly a deeply satisfying reprieve. Raburn had just completed five days of frantic, 4:30 a.m. conference calls to secure funding after the hedge fund Highland Capital Management decided not to invest in Eclipse. Highland requested two seats on Eclipse’s board, he says, and preferred creditor status in case the company had to be liquidated, a move that Raburn contends sunk the deal. “The assholes at Highland, they waited until the 23rd-and-a-half hour to make demands,” Raburn tells me. “It was clearly a premeditated attempt to put the company into bankruptcy. There will be retribution.” Highland declined to comment.

Raburn averted bankruptcy by hours, and the near crash was yet another ­reminder that, while the laws of physics govern how airplanes fly, money is what really puts them in the air. “This project has been infinitely harder than I thought it would be,” he says. “It’s taken longer. And it’s taken more money.”

In 2005, raburn flipped one to his critics when he won the Collier Trophy, the Nobel Prize of aviation. When the F.A.A. certified his plane at a ceremony shortly afterward, the agency’s administrator, Marion Blakey, said the Eclipse would “change the face of aviation.”

That prediction will be put to a real-world test this fall, when Florida-based DayJet introduces the first Eclipse air-taxi service. Ed Iacobucci, DayJet’s founder and C.E.O., has ordered 309 Eclipses, bringing Eclipse’s order book to more than 2,600 planes, worth more than $3 billion. A 2005 F.A.A. forecast predicted the market would support 5,000 V.L.J. deliveries by 2017. This July, Eclipse Aviation unveiled its latest design, a four-seat, single-engine model called the Concept Jet. If all goes according to plan, Raburn will go public sometime in the next two years.

Back in the air-conditioned comfort of Ra­burn’s conference room, I ask him which aviator he most admires. He grows animated talkin­g about Charles Lindbergh’s daring Atlantic crossing. I ask him where he sees the Eclipse in the pantheon of aviation icons. He pauses and turns reflective, the first time an answer doesn’t blithely spill from his lips. Finally, he replies, “The reason there’s history is because it’s the only accurate judge. If Eclipse delivers on all the prom­ises, it will become one of the com­panies recorded in aviation history. What role do I get in that? I’m not going to speculate. That is up to history to decide.”