Article - Issue 11, February 2002

Changing the way we fly: Boeing’s new Sonic Cruiser

Peter Rumsey

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Many airline passengers, particularly those travelling across or between continents would welcome both shorter flight times, and more direct flights between the world’s cities. With these factors in mind, Boeing has begun work towards a new and radically different aeroplane, designed to meet these needs.

Boeing is still largely a company of engineers. Even non-engineering departments are heavily populated with men and women trained and skilled in one or more engineering disciplines. The tools of our trade are numbers and analysis and we have to use these tools to meet the needs of our customers and the flying public. In other words, we work just as hard at understanding what the world wants as we do at understanding what we are capable of delivering. After all, for a commercial aeroplane programme to be a true success, it has to find wide acceptance around the world, not just be a technological marvel.

We have seen our customers and the flying public start to make a shift in what they want. The new Sonic Cruiser is a response to what Boeing sees as a fundamental shift in expectations. Gone are the days when passengers were content to hop from spoke to hub to hub to spoke, spending a day or more on long-distance flight. With the dawn of the Internet, people are becoming accustomed to getting what they want when they want it, and people are experiencing the world like never before. Ideas, products and customs are being shared with an immediacy never before possible. This sets the stage for manufacturers of all kinds of products to consider how they can meet the evolving expectations of the people who use their products.

Just as these shifts in public expectations have been happening, the world of aviation has seen a shift toward further deregulation of air travel. When the airways opened up, whole new opportunities evolved. One example to look at here is what has happened between one US city and Europe in less than 15 years. In 1987, the shadow of regulation still lingered in the US as airlines started to understand what the new environment of deregulation meant to them. There was one daily flight between Chicago and Europe, a TWA flight to London. Today, there are more than 22 flights from Chicago to 11 different European cities. The changes in regulation allowed airlines to pursue brand new routing structures – routes based on what their passengers really wanted: more direct flights.

As well as wanting more direct flights, passengers have demonstrated a preference for flights that take less time and aeroplane configurations that enhance comfort. It’s just common sense: people want to go where they want to go, when they want to go, how they want to go. Boeing’s answer to the demand for faster flights, more direct flights and increased comfort is the Sonic Cruiser.

The speed advantage

The Sonic Cruiser is being designed for maximum performance at speeds between Mach 0.95 and 0.98, just below the speed of sound. This compares with today’s commercial jet aircraft which travel at between Mach 0.80 and Mach 0.85. But we all know speed by itself is not very useful. Ask anyone who owns a sports car and drives in bumper-to-bumper traffic. The Sonic Cruiser is also being designed to cruise at higher altitudes than today’s aeroplanes – in the mid-40,000-foot level – accessing new, open airways that will allow pilots to get the best advantage from the aeroplane. So what does the combination of speed and increased altitude give to passengers?

Travel times will be reduced by 15 to 20%, depending on the distance being travelled – the longer the flight, the more the time saving. For example, on a flight from London to Singapore, passengers will arrive almost two hours earlier than those travelling the same route on conventional speed aeroplanes. What those two hours mean are really up to the traveller – two more hours of sight-seeing, two more hours at home with the family, two more hours to get ready for an important meeting. The flight will be smoother on the faster aeroplane too, because there is less turbulence at the higher altitudes. The speed advantage is significant for airlines too.

With an aeroplane that travels faster, an airline may need fewer aeroplanes to provide daily service on certain routes. For example, the flight between Los Angeles and Tokyo today takes just under 14 hours. It is impossible for an airline to have one aeroplane with a daily flight on that route. With the Sonic Cruiser, however, the flight could be made in less than 12 hours, allowing an airline to use a single aeroplane to provide a daily service. Of course airlines with a faster aeroplane will also be more likely to attract a greater number of passengers. Given the choice between Airline A with a fast aeroplane and Airline B with a slower one, passengers will surely choose Airline A.

The design philosophy

The Boeing design team has worked within a ‘design for the environment’ philosophy from the earliest days of the Sonic Cruiser programme. We have made improvements in the environmental performance of aeroplanes with every new generation. The Sonic Cruiser will continue that tradition.

Fuel burn will be approximately the same, on a per-passenger basis, as today’s best similarly sized aeroplanes. The technologies that allow this performance to be achieved remain classified, causing some doubt amongst sceptics. But the men and women working on the programme are convinced that it is realistically achievable.

The unique configuration of the Sonic Cruiser, with its long, integrated nacelles and its rapid climb rate plays an important role in minimising take-off and landing noise, always a concern to the neighbourhoods near airports. In addition, Boeing is working with General Electric, Pratt & Whitney and Rolls- Royce to ensure that the engines for the Sonic Cruiser use the latest engine technologies to minimise emissions.

Converging technologies

How will Boing manage to obtain both a real speed advantage and improvements in environmental performance?

The advances made in configuration technologies, especially computer-based three-dimensional design tools, have made it possible to try new designs and configurations with minimal risk or investment, allowing manufacturers to really look for innovative solutions to what airlines and passengers want. Aerodynamic design has also advanced through the utilisation of analytical programs that are made possible by the rapid computational speeds of today’s computers. Composite materials are now more durable and stable than previously thought possible, allowing new choices of materials to be used in the manufacture of aeroplanes. Manufacturing processes themselves, the use of laser-guided tools and other modern equipment, have helped make the building of such complex machines to be even more precise, less wasteful and quicker. Configuration, aerodynamics, materials and manufacturing process have all matured to a level that makes a different aeroplane possible.


Even when designers start with a clean sheet of paper, there are certain ‘musts’ that can never be forgotten, the commitment to safety being primary. The tragic events of 11 September have brought a new worldwide attention to aviation safety. The entire commercial aviation industry is working together to ensure the highest possible levels of safety for the commercial fleet. Being born under the spotlight of those events has put even more focus on incorporating the latest safety features in the Sonic Cruiser.

The family of aeroplanes

When the Sonic Cruiser enters revenue service in 2008, it will join a family of Boeing products. The new aeroplane is not intended to be a replacement for any of the company’s existing aeroplanes. It is opening a new spot in the market. Every product is optimised for performance at a certain range carrying a certain number of people. Boeing expects to introduce the Sonic Cruiser with a range comparable to the 777 with capacities similar to the 767. It will be optimised to serve 200–250 passengers travelling on medium- to long-range routes. The Sonic Cruiser will still be efficient on medium-range flights with fewer passengers or short-range flights; however, aeroplanes designed specifically for those routes with specific passenger counts may be more efficient.

Boeing expects that, given the anticipated growth in the industry, and the realities of production rate (only so many aeroplanes can be built, certified and delivered within a given time frame), current aeroplanes will continue to be ordered for many years to come. The day may come, long in the future, when today’s aeroplanes are replaced with designs similar to the Sonic Cruiser, but optimised for performance with the same routes and capacities of other aeroplanes. That will depend on how the world continues to change and what airlines and passengers decide are their priorities for the future.

Peter Rumsey is Director of New Airplane Product Development in the Product Strategy and Development department of Boeing Commercial Airplanes. He is responsible for all new commercial airplane development and understanding the potential of innovative projects to contribute towards the efficiency and cost effectiveness of future Boeing commercial airplanes. After working with the British Aircraft Corporation, he joined The Boeing Company in December 1965 and has a wide range of experience in the design and development of commercial airplanes. He was born in London, England. He was recently awarded the 2001 British Silver Medal by the Royal Aeronautical Society for his contributions to the development of aeronautics.

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