Second century of powered flight is heralded by jet's 5,000mph record

Powered flight has come a long way in a century and as Michael McCarthy explains Nasa is pushing it farther still
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Never mind supersonic. The age of hypersonic jet travel came a step closer at the weekend when an experimental plane belonging to the US space agency Nasa flew at seven times the speed of sound.

A white trail shooting across the clear blue sky off the southern California coast showed Nasa's unpiloted X-43A machine reaching Mach 7, or just under 5,000mph, and setting a new world speed record for a jet-powered aircraft.

It was a striking beginning to the second century of powered flight. The first ended last 17 December, on the 100th anniversary of Orville and Wilbur Wright's flight at Kitty Hawk, North Carolina, where the two pioneer brothers flew the first heavier-than-air machine 120 feet in 12 seconds.

That's about seven miles an hour - you could just about keep up, running alongside. (Wilbur tried to.)

The powered flight of the X-43A lasted a similar time, but in those few seconds it covered nearly 16 miles, before gliding hypersonically for another six minutes and then falling into the waters of the Pacific.

From Kitty Hawk to the X-43A has been a century's steady advance, through propeller-driven cross-channel and transatlantic flights to the first jet aircraft, and then space travel, but whether or not the next hundred years will show such a grand progression is hard to estimate. To go much further will certainly have to involve major technical advances.

This was the case with the X-43A. The flight marked a technical triumph for a revolutionary engine, the scramjet, or supersonic-combustion ramjet, which aviation engineers think may usher in a new era of powered flight, making space travel itself easier and more efficient.

In theory, the air-breathing engine could propel a plane to speeds that would enable around-the-world flights in just a few hours, and the US Department of Defence is known to be working on the technology, eyeing it for use in bombers that could quickly reach targets anywhere on the globe.

In theory too, it could power hypersonic passenger jets from London to Sydney in just two hours, but increasing environmental concerns about the contribution to global warming of the exhaust gases from high-flying airliners mean that future versions of Concorde are unlikely to be developed.

Concorde will probably turn out to have been both a first and a last.

Nasa, however, is delighted with the success of the X-43A and its scramjet, which could allow rocket-speed travel but with considerable savings in weight. Rockets must carry their own oxygen to combust the fuel they carry aboard; scramjets can scoop it out of the atmosphere. The engine could one day usher in a new generation of space shuttle propulsion systems.

The 12ft-long, 2,800lb X-43A was mounted on a Pegasus rocket booster and carried to an altitude of 40,000 feet by a modified B-52 bomber, which took off from Edwards Air Force Base in the California desert.

Once the B52 reached its cruising altitude the aircraft and its booster were launched in mid-air. At about 100,000 feet the rocket booster fell away, leaving the X-43A to fly under its own power for about 11 seconds. It then performed a series of manoeuvres in its glide before falling into the ocean,

In scramjets, oxygen is rammed into a combustion chamber where it mixes with fuel and spontaneously ignites. For the engine to work, it must be travelling at about five times the speed of sound - requiring an initial boost-powered flight that only a rocket can provide.

Nasa has built the X-43A under a $250m (£138m) experimental scramjet programme. The first X-43A flight ended in failure in June 2001, after the rocket used to accelerate the plane veered off course and had to be blown up.

A subsequent investigation found that pre-flight analyses had failed to predict how the rocket would perform, leaving its control system unable to maintain stable flight.

So the delight was all the greater when Saturday's flight went off successfully, and at the end applause rang out in the control room of the Dryden Flight Research Centre at Edwards. Griffin Corpening, Dryden's chief engineer on the project, said: "It's a great way to end, all the sweeter because of the challenges we've overcome through the life of this project."

The test has important commercial and military implications. "Efficient access to space opens up a whole new world for the future, to be able to get to space and back, and do it several times a month," said the project manager Joel Sitz.

"The ramjet-scramjet is the Holy Grail of aeronautics in my mind," Mr Sitz said.

The Nasa flight engineer Lawrence Hübner said preliminary data indicated that the needle-nosed X-43A reached a maximum speed of some seven times the speed of sound, or about 5,000mph, after the rocket boosted it to about 3,500mph. It was the first time an "air-breathing" jet had travelled so fast, he said.

The previous record for jet flight was held by the US Air Force SR-71 "Blackbird" spy plane, flying at Mach 3.2. The experimental X-15 plane, which was manned but rocket powered, reached Mach 6.7 in 1967.

However, despite the success of the flight at the weekend, technological hurdles mean it will be decades before such a plane could enter service.

Nasa's role in developing the technology remains in doubt, as the agency recently cut funding for more advanced versions of the X-43A.

Experts estimate that the first manned craft powered by scramjets would not take to the air until the year 2025.

Even so, from seven miles an hour to Mach Seven is a striking indication of how far powered flight has gone in a hundred years.

Aviation milestones

17 DECEMBER 1903: The American brothers Orville and Wilbur Wright make the first controlled, sustained flight in a heavier-than-air craft in a biplane at Kitty Hawk, North Carolina (below). The first flight (with Orville as pilot) lasted 12 seconds and covered 120 feet. The final flight of the day carried Wilbur 852 feet in 59 seconds.

25 JULY 1909: The Frenchman Louis Bleriot makes the first flight from France to England in his Bleriot XI monoplane, flying from Les Baraques near Calais to a field outside Dover in 37 minutes.

14 JUNE 1919: The Britons John Alcock and Arthur Whitten Brown make the first non-stop crossing of the Atlantic in a Vickers Vimy, from St John's, Newfoundland, to Clifden in Ireland.

20-21 MAY 1927: The American Charles Lindbergh makes the first solo flight across the Atlantic in The Spirit of St Louis, flying from Roosevelt Field, Long Island, to Le Bourget, Paris.

15 MAY 1941: The first jet flies at RAF Cranwell, Lincolnshire, a Gloster E28/39powered by an engine developed by Sir Frank Whittle.

14 OCTOBER 1947: The American test pilot Chuck Yeager breaks the sound barrier - Mach 1, about 700mph at sea level - in the experimental Bell XS-1 aircraft over Muroc Army Air base in California.

4 OCTOBER 1957: The space age begins as the Russians launch Sputnik 1, the first artificial satellite, a craft about the size of a basketball, orbiting the Earth in 98 minutes.

12 APRIL 1961: The Russian air force lieutenant Yuri Gagarin becomes the first person to escape the gravity of the Earth in making the first manned space flight in Vostok 1, completing a single orbit of the globe in 108 minutes.

21-27 DECEMBER 1968: The American astronauts Frank Borman, Bill Anders and Jim Lovell, the crew of Apollo Eight, become the first men to leave the vicinity of the Earth when they orbit the Moon and return.

2 MARCH 1969: First flight in Toulouse, south-west France, of Concorde, the Anglo-French aircraft which became the only supersonic jetliner to fly commercially. Concorde was in service for more than 27 years, from 1976 to 2003.

20 JULY 1969: Man walks on the moon. The American astronauts Neil Armstrong and Buzz Aldrin step down from the lunar module of the US spacecraft Apollo 11 in "one giant leap for mankind".

20 APRIL 1981: The space shuttle, the first reusable spacecraft, makes a successful flight into and back from space. Columbia, the first shuttle, piloted by John Young and Robert Crippen, takes off from Cape Canaveral in Florida and makes 36 orbits of the Earth before returning two days later to Edwards Air Force Base in California.