NASA Langley Research Center
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The pilot lines the Learjet up on the runway and pushes the throttles forward. Across the field at southern California’s Van Nuys Airport, the conference room’s windows vibrate a little. Inside, Clay Lacy leans across the table and shakes his head. “The most amazing thing to me about aviation is how slow we are going. We are basically flying at the same speed we did in 1959 when the [Boeing] 707 came out.”
Just beyond Lacy’s windows, a fleet of $30 million Gulfstreams and sleek Learjets crowds the airport ramp. Van Nuys is a concertina-wire-ringed cornucopia of all things that fly, save airliners, located smack in the middle of the San Fernando Valley. From opulent Boeing Business Jets to privately owned warbirds to lowly Cessna 152 trainers, it’s all here. The place reeks of kerosene and money.
Clay Lacy is a retired United Air Lines Boeing 747 captain. Over six decades he has flown everything from DC-3s to Mach 2 fighters. Today, he owns Clay Lacy Aviation, an executive aircraft charter, management, and service company, and is a leading spokesman for corporate aviation.
Since 2001, Lacy has served as an advisor to Supersonic Aerospace International, a venture committed to building a supersonic business jet (SSBJ). In October 2004 SAI unveiled its design for an SSBJ at the National Business Aviation Association annual convention. At the same convention another company, Aerion Corp., a Reno, Nevada-based company founded in 2002, announced its intention to build a competing supersonic jet.
The two announcements were accompanied by a sea of press releases, a torrent of publicized patent filings, artful models and renderings, and much talk about the need to enlist “risk-sharing partners” to help finance what will surely be a long, expensive, and technically and politically challenging endeavor.
The overall development cost for each program was pegged at $1.5 billion to $3.5 billion, and the per-aircraft price was estimated at $80 to $100 million. Surveys had shown a potential market for 300 aircraft worldwide, about par for deliveries of a successful bizjet.
The team members behind these designs had impressive pedigrees, but the members of the NBAA were still skeptical, for it was not the first time the supersonic tease had been danced before them. In 1989, U.S. business jet builder Gulfstream teamed with the Soviet Union’s Sukhoi design bureau to launch the S-21, and in 1998 French jet fighter and business jet maker Dassault took the wraps off a tri-jet SSBJ design. Then, the unsolved problems of mitigating the sonic boom, developing durable engines, and shifting corporate priorities relegated these projects to the back burner. But for many in the corporate jet community, the dream of speed was never far away. And a near-supersonic airplane called the Citation X had whetted a lot of appetites.
Cessna, a company known for its line of small- and medium-size Citation business jets, delivered its first Citation X in 1996. The “Ten” had a plain vanilla, eight-seat cabin and sold new for $12 million. But it could cruise at 49,000 feet at .92 Mach and was rumored to have broken the sound barrier during flight testing. With the Ten, Los Angeles to New York became a four-hour trip, beating the competition by over an hour.
Golfing legend and seasoned bizjet pilot Arnold Palmer took delivery of the first Ten. In 1997, he told writer Jeffrey Rodengen about a conversation he’d had with an air traffic controller as he flew his Ten past the slower airliners. “The other day, on a trip down to Florida, the air traffic controller said, ‘Hold up a minute Arnie. I’m going to see if that pilot ahead of you will let you play through.’ ”
Ten operators love it, demonstrating to the bizjet community what automakers have known for years: Speed sells. But the Ten also showed that you could get that speed for less money than had previously been assumed. Today, the Ten costs a little more than half of a new and much larger Gulfstream 450 and burns about 40 percent less fuel flying the same mission.
The same year the Citation X made its debut, Boeing and General Electric announced the launch of the Boeing Business Jet, a modified 737 airliner outfitted with longer-range fuel tanks and winglets. Customers would buy the BBJ “green,” or unfinished, for around $33 million, then spend whatever they wanted on custom paint and interiors. And spend they did, with the average BBJ finished price heading well north of $50 million. Prior to the BBJ, the top-end market for corporate jets ran in the $40 million range. Of course, there were well known exceptions to even this level of excess: The Saudi royal family had been outfitting 747s and Lockheed L-1011 jumbo jets as flying palaces for years, and at nine-figure prices few could fathom. But the market was shocked by the BBJ’s level of success—100 have been delivered through mid-2005—and it wasn’t long before Airbus rushed to market with a competing aircraft. The BBJ demonstrated that, within the corporate jet market, there were customers in a rarefied niche who would spend almost anything if it meant they would be flying a much larger aircraft.
But even with this seeming disregard for price and the confirmed need for speed among bizjet buyers, supersonic has long been the third rail of commercial aviation. For decades, analysts and manufacturers have viewed a supersonic aircraft as noisy, financially risky, and politically toxic. In the United States, supersonic flight over land by any non-military aircraft is, in fact, illegal (Federal Aviation Regulation 91.817). Many other countries have adopted similar prohibitions.
Beginning in 1958 and largely in response to the supersonic Anglo-French Concorde airliner, the United States sank more than $1 billion into civilian supersonic research, capping it with the very public cancellation of its supersonic transport program in 1972. For those who opposed it, the SST embodied all things wrong with technology. In his 1970 anti-SST tome, William A. Shurcliff, director of the Citizens League Against the Sonic Boom, perfectly captured the histrionics of SST opponents when he wrote: “If overland supersonic flight is permitted, 500,000,000 persons in America, Europe, and Asia may be jolted every hour, day and night by sonic booms from hit-and-run SSTs. People working, relaxing, sleeping will be banged repeatedly, without apology. Surgeons performing delicate operations will be startled, and their instinctive reflex reaction may cause permanent harm to the patients…. Aviation, instead of being man’s servant, would be his scourge.”
The abrupt death of the American SST program, coupled with the slow bleed outs of the Soviet Tu-144 and Anglo-French Concorde programs, did not end research into supersonic transport, but did slow it down. In the United States, funding for such research dropped from about $100 million a year to $13 million under the guise of NASA’s Supersonic Cruise Research program. But even as the anti-SST drumbeat was reaching its crescendo, science was getting results that would make the protests irrelevant. It just wasn’t happening fast enough.
In 1964 NASA scientist F. Edward McLean hypothesized that changing an aircraft’s shape could minimize its sonic boom. Seven years later, two scientists at Cornell University, Richard Seebass and Albert George, published an algorithm “for defining the minimizing equivalent area distribution based on flight Mach number and altitude, and the aircraft’s length and weight.” In other words, it was not only possible to mitigate an aircraft’s sonic boom by altering its shape, you could also use a mathematical model to predict the boom signature of any given shape. NASA validated Seebass-George during 1972 wind tunnel testing for regimes at Mach 1.5 and 2.7. (The model was more accurate at the lower Mach number.) However, it would be more than 30 years later, on August 27, 2003, that these theories were tested on an actual aircraft by the Defense Advanced Research Projects Agency’s Shaped Sonic Boom Demonstration, part of DARPA’s Quiet Supersonic Platform program (see “The Boom Stops Here,” Oct./Nov. 2005).
Predicting and quieting sonic booms are only part of the new science driving the development of the supersonic business jet. The other involves supersonic natural laminar flow.
An aircraft experiences a certain amount of drag from skin friction as air moves across the wing and gives rise to turbulent “boundary layers.” Laminar flow describes air immediately next to the wing, which flows in a series of smooth layers, free of turbulence, resulting in less aerodynamic drag on the wings and improving range, speed, and fuel economy. It is virtually impossible to achieve extensive laminar flow on a subsonic aircraft. Supersonic aircraft offer more possibilities, but their potential for laminar flow is often defeated by design factors, like a highly swept wing, which invariably creates turbulence and drag.
NASA experiments in 1995 and1996 used the delta wing on an F-16XL fighter jet, modified with a power-suction “glove,” to improve laminar flow. According to laminar flow expert and aerodynamicist Richard Tracy, a normal F-16 wing “has too much sweep to support laminar flow and has a slightly blunted [wing] leading edge…and thus a very high wave drag at its maximum supersonic speed.”
While suction gloves seek to improve laminar flow on swept-wing designs, natural laminar flow relies on a wing’s shape alone, without help from other devices. Greater wing sweep produces greater turbulence, thus a natural laminar flow wing has very little sweep, a design that helps stabilize airflow.
The first widely known aircraft to take advantage of this principle was Lockheed’s F-104 Starfighter, a Mach 2 interceptor developed in the 1950s. In 2000, NASA and DARPA teamed up with the Reno Aeronautical Corporation to demonstrate a three- by four-foot natural laminar flow test article mounted to the belly of an F-15B fighter and flown up to Mach 2 at 45,000 feet. The demonstration validated the theory and led NASA to speculate that natural laminar flow had the potential to enable supersonic aircraft to produce “economies comparable to, and in some cases better than, subsonic aircraft in the same role.”
Based on these latest rounds of research, two camps sprang up to test the market.
Supersonic Aerospace International was founded in 2001. It is funded by the estate of Clay Lacy’s friend Allen Paulson (see “The Used Airliner King,” below). Aerion was founded in 2002 and is bankrolled by Texas billionaire Robert Bass.
In 1978 Allen Paulson purchased Grumman’s foundering line of civilian aircraft, including the Gulfstream business jet. Over the next decade Paulson shaped Gulfstream into the ultimate status symbol. From corporate chieftains to foreign potentates to the glitterati, nothing said “Mine’s bigger” quite like a Gulfstream.
By 1985 Allen Paulson had parlayed his 1978 $58 million purchase of Gulfstream into a $637 million cash and stock sale of the company to Chrysler, but stayed on to run the company. He had also launched a wildly successful follow-on aircraft, the G-IV, a 4,000-nautical-mile-range model with all-digital avionics and more fuel-efficient engines. By 1988, Paulson knew what the next big thing was: supersonic.
In 1989 he teamed up with Mikhail Simonov of Sukhoi to develop the Gulfstream-Sukhoi SST, the S-21. Under the plan, Sukhoi would build the airframe while Gulfstream would be responsible for integrating the engines and avionics. The marriage would be short-lived: Chrysler elected to cash out of Gulfstream later that year. The company’s new owner was the New York investment banking firm of Forstmann-Little, and it became clear very quickly that the prime target on its radar was not a supersonic bizjet. “In the early 1990s, Gulfstream bet the company on the [development of the long-range, subsonic] G-V,” says Pres Henne, Gulfstream’s senior vice president for Programs, Engineering, and Test. “Anything else was a very low priority.”
Forstmann installed its own CEO to run the company and Allen Paulson retreated to the world of thoroughbred horse racing and other investments.
Although Paulson was out of aviation day-to-day, the idea of a supersonic bizjet “was never far off his mind,” according to Clay Lacy. By the mid-1990s he began having regular conversations with engineers and managers at Lockheed’s Advanced Development Programs plant (the Skunk Works) in Palmdale, California. One of them was a program manager named Tom Hartmann.
In 1998 Lacy flew Paulson up to Palmdale for a meeting with Hartmann and Ed Glasgow, Lockheed’s vice president for advanced development programs. Having successfully launched the G-V, Gulfstream was again able to devote modest resources to supersonic research, this time in partnership with Lockheed and with $20 million in federal support. Lacy recalls the meeting: “They told us they had technology to suppress the sonic boom but gave no great detail.”
Paulson died in 2000, and by that time, Lockheed and Gulfstream had parted ways. Gulfstream brought its supersonic research in-house. But Paulson’s estate designated funds in trust for the design of a supersonic business jet. In 2001, Paulson’s son, Michael, himself a veteran of the bizjet industry, formed SAI and hired Lockheed to conduct feasibility and design studies for a small supersonic business jet. For three years a team of up to 40 engineers ran through $25 million doing just that.
The result is the Quiet Supersonic Transport (QSST), and SAI announced the program at NBAA in 2004. Its designers claimed that its patented sonic boom suppression technology gives it a boom signature less than one percent of the Concorde’s.
The Aerion also debuted at NBAA in 2004, and it made another appearance in 2005—with a number of modifications, including the rounding of the wings’ leading edges where they meet the wing strake. “A straight edge created too much shock in our wind tunnel tests, and detracted from the aircraft’s laminar flow capabilities,” said Richard Tracy, Aerion’s chief technology officer, at the company’s press conference at the NBAA convention (see “The Challenger,” p. 45). The aircraft will be powered by a pair of Pratt & Whitney JT8D-219 engines (also found on the McDonnell Douglas MD-80 series), which will provide Mach 1.6 cruise.
While these engines may be quiet enough, questions of durability remain. With the exception of the Concorde’s earth-shaking, fuel-ravenous Olympus engines, no civilian jet engine has ever demonstrated robustness at sustained supersonic speeds. Indeed, even most military engines have upper thermal limits, as they typically are thrown into afterburner for only a few minutes at a time. However, the Air Force’s F-22A Raptor is equipped with Pratt & Whitney F119 engines and has the ability to supercruise—to fly at supersonic speeds for long periods of time—without the noise and high fuel consumption of an afterburner.
Other than its smaller size, the Aerion, unlike the QSST, contains no specific boom suppression or reduction technology. Because regulations prohibit supersonic flight over land, a potential competitor of Aerion’s questions the aircraft’s market appeal. “High subsonic overland does not make sense” for a supersonic business jet, says Gulfstream’s Henne.
“Our market studies were very explicit that the model in question would not be able to fly supersonically over the U.S.,” says Tracy. “In fact, the majority [of those surveyed in the Aerion market study] would purchase the non-supersonic overland model,” even if a quiet supersonic aircraft that could fly over land were to become available five years down the road.
In Tracy’s opinion, “it is doubtful that any definitive regulation [regarding supersonic flight over land] will be forthcoming” before a supersonic bizjet model is built—another reason Aerion isn’t focusing on low-boom shaping. “There is a drag penalty associated with aircraft shaping to decrease sonic boom levels,” says Tracy. “[And that] translates into larger engines, higher fuel burn…and increased costs.”
To the untrained eye, the Aerion resembles an F-104 with an even more pointed nose. It relies on natural laminar flow to achieve speed and economy. It is not surprising that Richard Tracy, who owns Reno Aeronautical Corporation, is one of the company’s principals. During the 1980s, Tracy teamed with Stanford University aerodynamicist Ilon Kroo and Jim Chase, a former colleague of bizjet legend Bill Lear, on different configurations for a supersonic transport in their “free time.”
“I had this passion since graduate school days to see supersonic become a practical mode of flight,” Tracy says. By 1987, the group was on the verge of giving up. “Nothing looked like a significant breakthrough,” says Tracy. Then one night he was awakened by the thought “Why not look at laminar flow?” The idea had been in his subconscious since his days at the von Karman Institute in Belgium in 1959. To Tracy, the advantages of a supersonic natural laminar flow wing were abundantly clear. He was confident that others would see so too, and that he would have no trouble securing research funding to prove the concept. He couldn’t have been more wrong. For 14 years he was politely received, often more than once, by all the major business jet and airliner manufacturers, a variety of other companies large and small, and a broad cross-section of individual investors. They offered praise and encouragement, but no funds. Neither did NASA, until the late 1990s, when DARPA came through with funding for the F-15 experiment.
Serendipity struck when Tracy’s work came to the attention of Robert Bass, a billionaire with a passion for aviation and technology. Bass hired Michael Henderson, who had managed Boeing’s NASA-funded High Speed Civil Transport program during the 1980s, to do further research on the work of Tracy’s group. Henderson reported back favorably and Bass invested.
When it comes to the supersonic bizjet, SAI and Aerion are not the only games in town. At NBAA in 2005 Gulfstream focused on its new Supersonic Acoustic Signature Simulator II. The mobile audio booth, housed in a white trailer, enables listeners to experience the loud double-bang of the Concorde followed by the far quieter “Gulfstream whisper,” and replicates the sounds in environments ranging from noisy city streets to a playground filled with children. The “whisper” is the sound a supersonic bizjet—traveling at Mach 1.8—would make if it were fitted with a special spike for reducing the sonic boom. The spike, for which Gulfstream received a patent in 1994, would extend from the nose of the airplane during supersonic flight, and retract during subsonic flight.
The simulator is Gulfstream’s bid to take the idea of changing regulations regarding supersonic flights over land directly to the people who will be making those changes: Everyone from environmentalists to the Federal Aviation Administration has been invited to step into the trailer and hear, or not hear, Gulfstream’s “whisper.”
Dassault also continues to work quietly on its designs, and NASA remains a prime funder of supersonic research that someday could be applied to a supersonic bizjet. Its pallet of programs includes the Ultra-Efficient Engine Technology program, which focuses on reduced emissions, lower noise, and higher-efficiency designs.
Currently, NASA is working with a group of 10 companies called the Supersonic Cruise Industry Alliance (SCIA), or the “Super 10.” Members include engine builders Rolls-Royce, GE, and Pratt & Whitney; airframers Boeing, Cessna, Gulfstream, Lockheed Martin, Northrop Grumman, and Raytheon; and fractional-share business jet provider NetJets. The group’s goal: supersonic civilian flight within 10 years.
A similar group, called HISAC, for High-Speed Aircraft Industrial Project, has been formed in Europe. Members include EADs, the parent of Airbus; Dassault; and Sukhoi.
Last summer, SCIA member companies submitted papers on the state of the art of supersonic technology to NASA as the agency moved forward with funding additional supersonic research, which could include a demonstration aircraft. “It’s going to put NASA in the position of being a smarter buyer,” says Eric Brachhausen, vice president of American Technology Alliances, a non-profit group that provides coordination services to the Super-10.
Building a successful demonstration aircraft is seen as a crucial step in eliminating the ban on supersonic civilian flight. “Somebody has to build it and the correct agency is NASA,” says Gulfstream’s Henne, who thinks that anyone who builds a supersonic bizjet before the regulations are changed is shouldering an unacceptable risk. “You don’t enter the market while there is still a prohibition.” Michael Paulson, on the other hand, says SAI will continue to move forward with or without regulatory changes.
If a supersonic business jet is built, the manufacturer will likely be a consortium of companies. The financial risk and resources required are simply too great for a single company to bear. Brachhausen and others believe that once the technology for a supersonic bizjet is successfully demonstrated, it will quickly be applied to other aircraft, including airliners. “If you focus on the boom first, you are led to the conclusion that the problem is easier to solve in smaller aircraft first,” Brachhausen says. “The intent is to bring those principles forward in a larger scale, higher capacity aircraft.”
For Richard Tracy, it’s not a question of if, but when. “I don’t see any reason why this won’t happen. And that is the same sense the aircraft manufacturers are coming to.”
SAI and Aerion have said that they can have a supersonic airplane flying by 2011. Pres Henne thinks that if regulatory approval can be won, a 2015-2016 window is more likely.
On the day that aircraft first takes flight, people in the world of business jets may reflect on Allen Paulson’s contribution. “There were times when he was a lone candle in the wind,” says Lockheed’s Tom Hartmann. “Ten years ago almost no one was talking about supersonic business jets. Now the whole industry is talking about it. In that sense, he’s already succeeded.”
And thanks in part to his efforts, one day when a Learjet takes off from the Van Nuys Airport runway and rattles Clay Lacy’s conference room windows, it will be followed by a much quieter—and much faster—airplane.
Sidebar: The Used Airliner King
Forty years before he bought Gulfstream, Allen Paulson had been working as a hotel janitor in Clinton, Iowa, when he won a $100 bingo game. He used the proceeds to buy a bus ticket to California where he was befriended by a barnstormer named Tex Rankin, who cultivated Paulson's interest in aviation. Paulson enrolled in an airline mechanic training program and was hired for 30 cents an hour at TWA.
After service in the Army Air Forces he rejoined TWA as a flight engineer aboard Lockheed Constellations and started a side business selling aircraft engine modifications. By 1951, Paulson's California Airmotive had become a full-time career and he shifted his focus to buying used airliners and converting them to cargo haulers. In 1967, Paulson founded another company, American Jet Industries, to convert old piston airliners into jetprops. During the 1960s Paulson bought and sold 300 airliners including Constellations, DC-3s, DC-7s, and Electras. In one transaction he snapped up Eastern Airline's entire remaining fleet of 42 piston aircraft. By 1969 Paulson's annual revenues topped $14 million and Newsweek proclaimed him the “used airliner king.”
“At one time he had more airplanes than a major airline,” remembers son Michael Paulson.
Allen Paulson died in July 2000. Just a year later, Michael, himself a veteran of the bizjet industry, formed SAI and hired Lockheed to conduct SSBJ feasibility and design studies.
Sidebar: The Challenger
Richard Tracy built his first model airplane when he was five and started attending the free Friday night lectures at the California Institute of Technology when he was 13 years old. While his classmates were grooving to Benny Goodman, Tracy was immersing himself in high-energy physics. He made extra money washing and polishing airplanes on weekends and soloed at age sixteen. His favorite airplane was a 1936 Taylor Cub. “Forty horsepower and no brakes,” he recalls.
Tracy received his undergraduate and masters degrees at CalTech before heading off to the NATO-funded von Karman Institute (VKI) for aeronautics and fluid dynamics in Belgium in 1959. It was there that he began to explore the field of supersonic natural laminar flow. His work at VKI convinced him to switch his field of study to aerodynamics, and in 1964 he received a doctorate from CalTech in hypersonic aerodynamics.
At Van Nuys Airport, Tracy became friends with bizjet genius Bill Lear. After Lear sold Learjet and moved to Reno, Nevada, Tracy would visit him there, and it was there that Lear made him an offer he couldn't refuse: chief engineer for a group developing a new business jet called the LearStar 600.
The 600 was a revolutionary design featuring a wide cabin, supercritical wing, and new high-ratio bypass engines that had been developed for Navy submarine-hunting aircraft and the Air Force's A-10 Warthog tank-buster. Lear ended up selling the design and his plans for follow-on jets to Montreal's Canadair, which rebranded the airplane the Challenger 600. Before the Challenger was even on the market, however, Lear tried to interest the company in follow-on designs including supersonic and near-supersonic models. Canadair wanted no part of it.
Tracy, much like his friend Lear, was committed to the idea of supersonic flight. His theories on laminar flow stem from work he was doing when he was still at the von Karman Institute, and they are the foundation for the Aerion’s program development process.