Posted on 05/29/2010 10:24:41 PM PDT by ErnstStavroBlofeld
Following the longest flight yet by an air-breathing scramjet engine, the X-51A Waverider team is waiting to see whether the largely successful first launch of the hypersonic demonstrator will unlock funding for further development of the technology.
The X-51A was launched over the Pacific on May 26, achieving scramjet ignition and acceleration, but the engine ran for only 200 sec. rather than the 300 sec. planned, and the vehicle reached around Mach 5 instead of accelerating beyond Mach 6. When it began to slow down and telemetry was lost, the flight was terminated and the vehicle destroyed, says Charles Brink, U.S. Air Force Research Laboratory (AFRL) program manager.
“We were 95% successful,” he says, adding that the cause of the slow acceleration and short duration is not yet known. Three more X-51As have been built, but their flights are on hold because delays in flying the first vehicle have consumed most of the available funding. The team hopes the flight’s success will unlock new sources of funding and allow tests to resume in 2011.
The Air Force Flight Test Center at Edwards AFB, Calif., had been criticized because of repeated delays caused by the availability of the B-52 launch aircraft, but Brink praises the test team for “putting us on point” for the May 26 launch.
The X-51A booster-and-cruiser “stack” was released by the mother ship at around 50,000 ft. and Mach 0.8. The stack separated cleanly and the booster ignited as planned, taking the vehicle to Mach 4.8, where the cruiser separated and executed a planned roll maneuver.
After slowing to Mach 4.73, ethylene was used to ignite the scramjet, which then transitioned to JP-7 hydrocarbon fuel. The X-51A began to accelerate, but slower than expected—up to 0.15g instead of the projected 0.22g. “We were seeing higher temperatures in the back of the engine bay, but have no idea why,” Brink says.
After reaching around Mach 5, the vehicle began to slow. When telemetry was lost, range safety officials decided to terminate the flight by destroying the vehicle.
I’ve worked on that exact plane. When I got to Edwards the program was over.
Basically speaking, "stoichiometry" is the process of calculating the concentrations of products of a chemical reaction.
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