Concorde is grounded and gone, but its legacy is very much alive. Such is the pulling power of supersonic flight that the minute a manufacturer suggests it will resurrect a new programme, news agencies everywhere sit up and take notice. Speeds that make the world accessible twice as fast appeal to almost everyone. There is only one snag… Supersonic flight is hellishly noisy and consequently banned over land in many parts of the world. Shock waves develop around airplanes as they near speeds of Mach 1, and at ground level these are perceived as a loud double boom or bang.
Many manufacturers, however, are undeterred by the ban because they believe they have solved the noise problem. Their enthusiasm is infectious. The draw is in the journey times. In a supersonic business jet (SS BJ), New York-to-Paris flights will take four hours and 15 minutes versus about seven-and-a-half hours in existing subsonic aircraft. Aircraft designer Aerion, for example, states that it has already secured around 50 orders for its US D80-million SS BJ from customers in key markets that include Europe, the Middle East, Asia and the US . Vice chairman Brian Barents said, “This is a tremendous validation of the aircraft’s appeal.” Owners of an SS BJ need not fear that they are stepping into the unknown. The exterior of the aircraft’s narrow elongated fuselage looks futuristic. However, the interior looks more like a conventional business jet, light with comfortable leather seats. By the time it comes to market — if it does — it wouldbe equipped with state-of-the-art Internet and satellite communications technologies as well.
Barents has said in the past that Aerion would like to get the first six jets off the production line by 2015. However, this depends entirely on the company finding someone willing to manufacture his aircraft — which will likely cost US D3 billion by the time the first one rolls out. Aerion had hoped to find a willing and able manufacturing partner by the end of last year, but its hopes were dashed by the global recession. Should Barents eventually realise his goal, the SS BJ will be able to fly at a top speed of Mach 1.6 carrying eight to 12 passengers and travel at both supersonic and subsonic speeds. Barents reckons that Aerion is “at least seven years ahead” of major competitors Gulfstream, Dassault and Sukhoi, all of whom are developing technologies optimised for supersonic flight only. He said, “I would not base my business model on a rules change.”
He also pointed out that since the world is two-thirds water, the jet could fly over these areas at unrestricted speeds on many trips, as well as over certain parts of Canada, Australia and Siberia. This would be useful for operators flying, for example, from Chicago to Paris, or Frankfurt to Dubai. An Aerion would take nine hours, 33 minutes from New York to Tokyo, flying at its no-boom limit over the US with a stop in Anchorage, compared with 14 hours, 21 minutes for a non-stop Gulfstream V.
Other bizjet manufacturers studying supersonic flight include Gulfstream and Dassault. Both are working hard on key technologies, in particular sonic boom reduction. John Rosanvallon, Dassault Falcon’s CEO said, “Dassault wants to be part of the international team that builds the first supersonic business jet.” However, Dassault seems to have parked its plans for the time being as it concentrates on other products.
Gulfstream has been working on supersonic flight for decades. In the early ‘90s, it worked with the Sukhoi Design Bureau of Moscow to develop a supersonic small business jet, code-named the S-21. Commitment to the project wavered and Gulfstream eventually dissolved the partnership, although Sukhoi continued work on the S-21.
Recently, Italian aviation giant Alenia was reported to be in talks with Sukhoi to bring a new supersonic business jet to market by 2015. The plane is slated to fly at more than Mach 1.6 and carry eight passengers with muffled sonic booms. Sukhoi and Alenia are collaborating on the Superjet, a commercial airliner, which is now in flight-testing. Others also wish to muscle in on the market. Back in 2001, Michael Paulson founded Supersonic Aerospace International (SAI) to fulfil his late father’s wishes as outlined in his will. Allen E Paulson wanted to create a ‘quiet’, low-boom supersonic business jet, and hired Lockheed Martin to complete a feasibility design study for such a revolutionary passenger aircraft. The study resulted in the design of the Quiet Supersonic Transport (QSST ), an aircraft that would have a sonic signature 1/100th that of the Concorde at a speed up to Mach 1.8, and a range of 4,000 nautical miles (7,400 kilometres). SAI is looking for a consortium to develop the QSST .
Hush Tech
Slated to cruise at 60,000 feet (18,288 metres) at speeds of Mach 1.6 to 1.8 (approximately 1,218 to 1,370 miles per hour/1960 to 2204 kilometres per hour), with a range of 4,600 miles (8,519 kilometres), the twin-engine airplane was designed to create a sonic boom only 1 per cent as powerful as that generated by Concorde. This result was achieved by making a long fuselage to ensure that individual pressure waves generated by each part of the aircraft structure do not impact as heavily on each other. The idea produces a longer, but quieter boom.
Gulfstream, meanwhile, is focusing on sonic boom noise reduction using ‘Quiet Spike’ technology, which it has flown on a NASA F-15 flight test aircraft capable of flying at speeds in excess of Mach 2.0, or twice the speed of sound. The company has developed a telescopic spike that extends from 14 feet (4.27 metres) in subsonic flight to 24 feet (7.32 metres) in supersonic flight. This spike flattens out traditional spiky ‘N’-wave sonic boom pressure waves into more rounded shapes, shaped roughly like a sideways ‘S’. This modification creates a softer sound that is quieter than Concorde’s sonic boom by a factor of 10,000. The manufacturer is also working with the International Civil Aviation Organisation, the US Federal Aviation Administration and NASA to gain regulatory approvals for its work.
On the military front, Lockheed Martin and Boeing have both proposed concepts for future supersonic aircraft to NASA, which they say could be realised within 20 to 25 years. Boeing has opted for a plane with a V-tail and engines over the wing. This could carry 120 passengers and cruise at Mach 1.8 with a range of about 5,000 nautical miles (9260 kilometres). Boeing has also said that it could reduce the sound of a sonic boom to 65 to 75 decibels, which comes within the legal limits to operate at maximum speed over land. Lockheed, meanwhile, has designed a craft with an ‘inverted-V’ above the wing that cuts noise by smoothing out the shock wave in the air that causes the loud bang. Interestingly, Boeing has concluded that supersonic aircraft could be economically and environmentally viable in multiple markets. Should this happen, the age of Concorde could be on us again before we know it.
