The impact of the so-called sonic cruiser could be more far reaching than first imagined - even by Boeing

Guy Norris / Los Angeles

Boeing's faster, longer range commercial jet - popularly known as the sonic cruiser - appeared on the scene as fast as its nickname suggests. On March 29, the company unveiled the futuristic high subsonic transport concept with some haste and a flourish that was a touch "un-Boeing" in its showmanship. The slick public relations exercise was orchestrated for two main reasons: news of the secret project was beginning to leak fast, and it was an ideal way of diverting world attention away from Airbus and the launch of its A380-800.


Yet, as the dust settles and work begins on project definition, Boeing is finding its fast transport idea has excited more operator interest than even it expected. Speed, it seems, has not lost its enduring appeal. Yet it appears speed means different things to different airlines, and Boeing is working with key operators on how best to define a concept that satisfies as many as it can for a proposed entry-into-service target date between 2006 and 2008.

So what does the sonic cruiser mean to the market? And how might different airlines use the concept? These are among the questions Boeing is asking as it strives to define the basic capacity, payload, range and size by year-end. From here, says John Roundhill, vice president of marketing for new airplanes, "the market will drive the timing. The earliest in-service date (2006) reflects the earliest we could do it with 777 technology: systems, aluminium alloys, composites and derivative engines. The later date represents more significant changes to systems architecture, further engine developments, more composites and more advances all-round."

Most of the fundamental answers, therefore, lie with the airlines. They are being offered a baseline concept that is slightly larger than a 767-300 in terms of capacity and overall size. Different versions of this concept, offering a variety of range capabilities between 12,950km and 16,650km (7,000-9,000nm), are being studied and the airlines asked for input into all points between. "The process is primarily that of individual meetings with customers and internal trade studies to support it. It's high level things we're looking at - like route structure, networks and interior configurations. Should the aircraft be three-class, or maybe just first and business? What does this mean to the cross-section? We are also asking fairly intense questions about what it is going to be used for. So, if you want to fly to 12,950km or 16,650km ranges here's the respective performance data and the operating economics," says Roundhill.

Defining the market

Other options include greater frequencies on inter or intracontinental routes, leading to greater productivity. On the current Los Angeles-Tokyo-Los Angeles rotation, for example, aircraft take 26-27h to fly the round trip, so to operate a daily frequency requires two or three aircraft. Boeing says if 4h can be removed from the round trip, an airline could service the route with a single aircraft. For round trips on trans-continental routes such as Seattle-Boston, airlines now operate one aircraft per day. Using the sonic cruiser, the same route could be serviced by two aircraft providing three frequencies per day in each direction. In theory this faster aircraft could generate one extra leg per day, giving a productivity increase of around 50%.

The most distinct time advantage of speed naturally appears on the longest routes such as New York to Tokyo where the Mach 0.95 to 0.98 aircraft would save up to 2h on a polar routing and 4h on a non-polar routing. On the Los Angeles-Singapore route, currently out of reach to all but the 777-200LR/300ER and Airbus A340-500/600, the cruiser would save 2h 40min on a westbound leg, and 2h 35min on the return. The only downside of the sonic cruiser's projected flight envelope would be standard cruise altitudes above the beneficial tail winds of the jetstream. From Los Angeles to Sydney it would save 1h 55min westbound, and 1h 45min on the way back. One of the world's busiest long-haul air routes, the London to Sydney marathon, could be done non-stop in as little as 18h by the sonic cruiser versus the 23h one-stop service offered today.

Transatlantic traffic between London and New York would also see significant benefits and, though not quite on the scale of time savings offered by Concorde, westbound journeys would be 1h 15min shorter and eastbound trips some 50min less. The savings are more significant, and perhaps more relevant to destinations further into Europe from where supersonic services have never been possible. Flights from Rome to New York, for example, would be 1h 30min shorter and the return eastbound journey would be a full hour shorter than the current flight time.

"The jury's still out on what kind of initial applications will start, and where it goes from there," Roundhill says. "That will drive the family plan and is why we need to figure out what will be the right capacity, range target and growth range target." The baseline study is driven by what provides "value" to airlines, Roundhill says. "In the early days of the 777, all we really knew was that our customers had a lot of interest in a bigger twin. This time we know it's speed. The world has developed with more fragmentation, and we could support that with a smaller aircraft."

Mike Bair, who as the former vice president for business strategy and development was closely involved in much of the earliest work on the high speed concept, says the baseline study is focused on maintaining current operating costs regardless of how the airlines end up using it. "Operating costs are comparable to today's aircraft. Airlines will not have to charge a premium, but there is potential for higher yields. The aircraft will not require higher ticket prices but we expect airlines will target premium traffic when it first enters service. As fleets get bigger, airlines will transition the aircraft into economy operations."

Service segmentation, of the type previously provided only by Air France and British Airways with Concorde, or in the near future by Qatar Airways with the A319CJ, is a likely development, Bair believes. He cites the example of the Japanese "Shinkansen" bullet trains which link cities at an average speed of 270km/h (170mph), saying airlines could see the development of completely altered network dynamics. The Shinkansen operators charged a 30% premium for the faster service and the older, slower trains emptied of business travellers. The final result was more fast trains than slow ones.

The business case

Although the faster aircraft also use more fuel on a segment basis, Boeing believes there will be no effect on total airline fuel consumption because of the time savings generated through eliminating or reducing weather delays, direct routings and fewer take-offs and landings.

Boeing chairman Phil Condit says:"The opportunity in front of us is for a shift in the market, in the category of market segmentation: a premium product focused on premium clientele. But there is nothing in the design that says it will stay so, as it becomes ubiquitous. Our goal is to provide a product that is economically attractive compared with today's aircraft."

Getting the economics right for the airline is as important to Boeing as getting the cost-benefit equation right for itself. The manufacturer knows that if it gets its sums right, the sonic cruiser could be a best-seller. Bair sees a bright future for the basic concept, as well as potential single-aisle family derivatives. "We are still sizing the market, but any routes over 5h look attractive. This means the potential market is very large - possibly 5,000 aircraft - which makes this a very attractive business case for Boeing," he says.

Part of the company's optimism stems from the radical improvements made in production processes and techniques over the past decade. "Because of the 777, 737 Next Generation, Joint Strike Fighter [JSF, X-32] and Unmanned Combat Air Vehicle experience we have a significant tool chest. We hope to bring the aircraft to market for considerably less than we have done in the past. The recurring build cost will also be significantly less. We are comfortable with the cost side and believe it will be attractive to both customers and shareholders." He warns, however, that "the development cost is pure speculation at this point."

From a market perspective, Condit has few misgivings that Boeing is heading in the right direction with the concept. "Boeing does not enter a new market direction casually. We spent a lot of time with airlines before we unveiled the sonic cruiser. They are all very excited. Our guess remains there is a market for very large aircraft, but we think it is small and our resources are better invested in a smaller, faster unit." According to Condit, the high subsonic aircraft could provide Boeing with a new weapon in its ever tougher competitive struggle with Airbus. "There is no reason why we can't maintain the share we have now with the sonic cruiser."

Scotching the cynical view that Boeing's sonic cruiser is an elaborate spoiling tactic against Airbus's well-managed A380 marketing campaign, Boeing Commercial Airplanes president Alan Mulally says: "On a scale of one to 10, we are very serious - we're at 11. We believe it will change the travel experience. People want to fly to where they want to go. They do not get on an aircraft to fly, they fly to go somewhere. They want to go where they want, when they want, as fast as possible."

Mulally's view is founded mainly on the company's belief in fragmentation. For Boeing, the term carries the same weight as "Working Together" did for the 777 programme in the 1990s, and is backed by evidence from Randy Baseler, vice president for marketing. On the US-Japan routes, the 747 dominated with 80% of the traffic before the new bilateral was signed in 1997. Since then fragmentation has begun and 747s now account for 60% of the traffic. "Narita (Tokyo) is often considered so congested that aircraft size could only go up; in fact it is going down. The North Pacific is following the same pattern of fragmentation as the North Atlantic, but with the 777, not the 767," says Baseler. He adds: "Europe-Asia has even more opportunities for frequency growth."

Such was Boeing's belief in fragmentation that in the mid-1990s, it devised a Mach 0.90 to 0.92 "Pacific Fragmenter". "It was a 767-sized area-ruled aircraft and we never made it work," says Bair. The Coke-bottle shaped fuselage had no constant section, was structurally inefficient, and was therefore dropped. Over subsequent years an alternative configuration began to come together that provided the right answers.

"A number of things came together that allow us to fly transonically with a straight fuselage. The components are in place to allow area ruling to occur naturally - that's why the engines are at the rear. The second development was in engine technology, and more specifically the engine's developed for the 777 (see feature P107), and the third is the availability of advanced technology," Roundhill says.

The firm configuration of the baseline concept evolved under the bounteous umbrella of Boeing's 20XX project, a broad-based effort to develop a formalised toolbox for future aircraft rather than a new aircraft in itself.

A significant element of 20XX was configuration work on various shapes including the conventional, alternative and unusual such as the blended wing body. In late 1999 the high subsonic configuration evolved and by the late summer/early autumn of 2000 the idea was sufficiently well formed enough to be considered for firm discussion with the board. Talks took place in February this year, and the following month the first were held with the airlines. "We offered the sonic cruiser to airlines as an alternative to the 747X. Their response was unanimous, so we are going faster," says Bair.

Fast, in this case, is 15% to 20% faster than today's aircraft including the 747 which, at Mach 0.85, is acknowledged as the speediest subsonic transport in service. The range, which at 16.700km-plus is described by Bair as "incredible", is a fall-out of the aircraft's novel double delta aft wing configuration. The large wing area, augmented by a high speed inboard "glove", provides volume for very large fuel tanks. The wing is equipped with simple leading and trailing-edge devices providing current take-off and landing distances. "The high lift system can be simple because it is a big wing, which is good for performance and keeps the cost, weight and complexity down," adds Roundhill. Although far from defined, the outer end of the 777-style outboard wing section is tipped with the raked wingtip developed for the 767-400. "We have selected that as the baseline, but we have a lot more wingtip work to do," he adds.

Striking features

One of the most striking aerodynamic features of the concept is the prominent forward mounted canards that provide pitch control. The size and position of the canards can also be changed to adapt to centre of gravity shifts associated with any stretches of the constant-cross section fuselage, says Boeing. "The only issue with the canard is airport compatibility - jet bridge operators are good at running into things! We are in discussion on how not to hit the canard," adds Bair. Twin canted vertical tails, mounted above the semi-recessed engine nacelles, provide lateral control and active yaw stability. The relatively small size of the units suggests that, like the similar looking tails on the Lockheed SR-71, they are all-moving surfaces.

Like so much of the proposed concept, the final outcome of the design will depend on a complex matrix of market and technology-based trade studies. These range from the width of the cabin cross-section and its ability to hold standard lower hold cargo containers, to the application of electrically-actuated systems, advanced composites and fully integrated avionics. "We're considering things like a more electric aircraft kind of approach, and looking at much more integration of computing power within the avionics to improve reliability and reduce weight," says Roundhill.

The cross-section outcome also depends on the aerodynamic challenges associated with high subsonic cruise performance, tending to rule out a section as large as the 777. "We're likely to go for a slightly smaller cross-section than the 777 - that's my guess," says Roundhill. One "major" trade study is therefore focused on the impact on freight, and the importance of cargo in the overall sonic cruiser equation.

Materials choices range from current technology, 777-style, composites to the widespread adoption of non-metallics and advance materials. This includes high-performance composites such as Glare, a sandwich of high temperature aluminium composite. The study is also evaluating the use of composites for major structural elements such as the wingbox. The undercarriage forms the focus of an entirely separate trade study as well. "We will look at any suitable off-the-shelf components, but it will probably be a purpose designed unit as the undercarriage is really the guts of any design," says Roundhill.

Airlines appear to be competing to contribute to the extensive trade studies and design review of the sonic cruiser as it nears initial definition. The question on everyone's lips is: will they be just as eager to place the all-important launch orders when the time comes early next year?

Source: Flight International