An experimental X-43 pilotless plane on Saturday broke the world speed record for an atmospheric engine, briefly flying at 7 700kph — seven times the speed of sound, Nasa said.
The hypersonic aircraft, a cross between a jet and a rocket, was dropped from the wing of a modified B-52 bomber, boosted by an auxiliary rocket to an altitude of nearly 30 000m and flew on its own power for 10 seconds.
After the 10-second test firing, the X-43A glided through the atmosphere conducting a series of aerodynamic manoeuvers for about six minutes before plunging into the Pacific Ocean, as planned.
”This is a success, everything worked as planned,” said Nasa spokesperson Leslie William.
”For the first time we succeeded in separating two vehicles flying at Mach 7,” she said. ”So far everything has been successful.”
Project chief Vincent Rausch had earlier said the $230-million programme ”could mark the beginning of a revolution in aviation and space flight”.
Nasa says the prototype engine is destined to eventually power a new generation of space shuttles.
The test of the tiny prototype — only 3,6m in length and 1,5m in wingspan, weighing 1 088kg — marked the first time a non-rocket, air-breathing scramjet engine powered a vehicle in flight at hypersonic speeds, defined as speeds above Mach 5.
The previous world speed record was ste by an SR-71 ”Blackbird” spy plane, which flew at Mach 3,2.
An experimental X-15 plane was able to fly at Mach 6,7, but with a rocket engine.
The major difference between a scramjet and a rocket engine is that a rocket must carry its own supply of oxygen, while a scramjet, taking advantage of very high speed, extracts oxygen even from the extremely thin atmosphere at high altitudes. The scramjet engine has no moving parts.
Nasa described the X-43 as a cross between a jet engine and a rocket engine, called a ”scramjet”, for supersonic combustible ramjet, an engine resulting from 20 years of research.
A scramjet operates by supersonic combustion of fuel in a stream of air compressed by the high forward speed of the aircraft, as opposed to a normal jet engine, in which turbine blades compress the air.
Scramjets start operation at about Mach 6, or six times the speed of sound. Therefore, the aircraft needed to be boosted by an auxiliary rocket to its autonomous operating altitude.
Nasa said the scramjet technology seeks to launch air-breathing engines to ever higher altitudes without the weight oxygen canisters add, thus increasing payload capacity and eventually lowering the cost of orbital launches.
The X-43 has a theoretical top speed of 10 000kph but Nasa said it did not attempt to attain that speed during Saturday’s trial flight.
Flight officials nearly postponed Saturday’s test for fears of rough weather. A first trial back in 2001 saw the loss of the prototype. — AFP
