In 6 seconds, Air Force sets land speed record

UPDATE: The Air Force has now retracted its claim to a new record.

How far can you get in six seconds?

Could you make it about 3-1/2 miles from the steps of Norfolk's Granby High School to the sands of Ocean View?

Unimaginable, even if the traffic lights are in your favor. But that's about how fast a classified payload, being tested for the Navy, was propelled in New Mexico late Thursday, setting a new world land speed record.

The benchmark was established at the Holloman Air Force Base High Speed Test Track by engineers from the 846th Test Squadron.

A rail-mounted sled carrying the payload hit a top speed of nearly nine times the speed of sound, Blair Ponder, an Air Force spokesman, said Friday.

Don't expect to see the craft that did it in a museum someday, however. In the end, it all blew up. As planned.

That's why, for Navy brass, attaining the speed record may not be of as much interest as the results when the payload exploded. But where Air Force officials are trumpeting their triumph, their sea service counterparts are mum.

All that's been said is that the test sled carried something explosive for "a Navy customer," suggesting it might have been a warhead.

The successful test was one of two high-speed wins for the Navy on Thursday.

Earlier in the day at Naval Surface Warfare Center in Dahlgren, Va., an electromagnetic railgun sent a 7-pound, aluminum slug flying at about Mach 7.5 - more than seven times the speed of sound. That test was for research the Navy hopes will yield a weapon capable of firing missiles 200 nautical miles in a six-minute arc through outer space and back to land, guided by GPS.

As for the new speed record, it came about 11:20 p.m., Eastern time, when the rocket sled reached a speed of 6,589 mph - 95 mph faster than officials had anticipated before the test and 136 mph quicker than the previous record, Ponder said.

The old mark was 6,453 mph, set April 30, 2003, at the same facility.

The sled was more like a rocket train. There were three "pusher sleds" and a "forebody sled," Ponder said. Each part dropped away from the rear as fuel was expended, much like a multistage rocket such as the Saturn spacecraft that carried men to the moon in 1969 and the early 1970s.

The payload it propelled, designed by the Sandia National Laboratories, detonated at the north end of the track after traveling 3.61 miles in about 6 seconds, Ponder said.

The blast and the speed of the sled created multiple sonic booms felt throughout the Tularosa Basin area around the facility.

Engineers are still poring over data to see if the test results equaled a new Mach speed record. The 2003 test at the facility had posted a speed of Mach 8.6. Before Thursday's test, expectations were that the sled would hit Mach 8.9.

Mach is the measure of the speed of an object relative to the speed of sound. Simply put, an aircraft traveling at twice the speed of sound has reached Mach 2. But the formula to set the number must take into account such things as altitude, winds and temperature.

"That's a little more complicated" to determine, said Rob Sexton, another Air Force spokesman. "It needs to be calculated rather carefully." The number should be released in a few days, he said.

Whatever the final number, any speed demons who want to match it will need plenty of power. The sled's motors delivered a total thrust of 814,000 pounds.

Additionally, a tent filled with nonexplosive helium enclosed 2.77 miles of the track in order to reduce aerodynamic heating and drag on the payload.

The test facility, adjacent to the White Sands Missile Range, is intended as a bridge between laboratory experiments and full-scale flight testing for advanced weapons systems.

The 11-square-mile test facility, used by the Air Force, Navy, Army and Missile Defense Agency as well as some international and commercial customers, features a test track first built in 1949. At the time, it was only 3,550 feet long. Today, it stretches for 50,788 feet - more than 9-1/2 miles.

Steve Stone, (757) 446-2309, steve.stone@pilotonline.com