Boeing demonstrator breaks hypersonic flight record

By Andrea Shalal-Esa

WASHINGTON (Reuters) - Boeing Co's X-51A Waverider made history this week when it achieved the longest hypersonic flight by a jet-fuel powered aircraft, flying for 3-1/2 minutes at five times the speed of sound, the U.S. Air Force said on Friday.

The last of four unmanned experimental military aircraft built by Boeing flew for at a top speed of Mach 5.1 over the Pacific Ocean on May 1, the Air Force said. The total flight covered 230 nautical miles in just over six minutes before the hypersonic cruiser plunged into the ocean.

"It was a full mission success," said Charlie Brink, who runs the X-51A program for the Air Force Research Laboratory Aerospace Systems Directorate.

The Air Force said it was the longest of the four X-51A test flights and the longest air-breathing hypersonic flight ever. The technology opens the door to future practical uses for hypersonic jet-fueled aircraft.

A hypersonic aircraft developed by NASA used hydrogen as a fuel to fly briefly at even higher speeds in 2004, but it would take a giant fuel tank to fly for longer periods.

"All we have learned from the X-51A Waverider will serve as the bedrock for future hypersonics research and ultimately the practical application of hypersonic flight," Brink said.

A video released by the Air Force showed the Waverider dropping down from under the left wing of a B-52 bomber at an altitude of about 50,000 feet and then accelerating away at great speed, leaving behind a long vapor trail.

The cruiser accelerated to March 4.8 in about 26 seconds, powered by a solid rocket booster built by Pratt & Whitney Rocketdyne, a unit of United Technologies. After separating from the booster, the cruiser's scramjet engine lit and accelerated the vehicle to Mach 5.1 at 60,000 feet.

The vehicle continued to send back data to the control station at Edwards Air Force Base in California until it made a controlled dive into the Pacific Ocean.

"This demonstration of a practical hypersonic scramjet engine is a historic achievement that has been years in the making," said Darryl Davis, president of Boeing Phantom Works, the company's advanced research and prototyping arm.

"This test proves the technology has matured to the point that it opens the door to practical applications, such as advanced defense systems and more cost-effective access to space," Davis said.

The first of the four X-51A vehicles flew in May 2010, hitting nearly Mach 5 for nearly two and a half minutes.

The nearly wingless X-51 was made using mostly standard aerospace materials such as aluminum, steel and titanium, although some carbon composites were used in the fins. For heat protection, the vehicle used insulation tiles similar to those used on board the NASA Space Shuttle orbiters.

The Air Force said the four X-51As were built to demonstrate the new technology, not as a prototype for a new weapon system. The program is aimed at paving the way to future hypersonic weapons, hypersonic intelligence, surveillance and reconnaissance, and future access to space, it said.

Since scramjets are able to burn atmospheric oxygen, they can be made lighter than conventional rockets, which may allow satellites to be launched into orbit more efficiently and cheaply.

(Reporting by Andrea Shalal-Esa; Additional reporting by Don Pessin; Editing by Tim Dobbyn)

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DARPA releases cause of hypersonic glider anomaly

LOS ANGELES (AP) — An unmanned hypersonic glider likely aborted its 13,000 mph flight over the Pacific Ocean last summer because unexpectedly large sections of its skin peeled off, the U.S. Defense Advanced Research Projects Agency said Friday.

The Hypersonic Technology Vehicle-2, launched from Vandenberg Air Force Base, Calif., atop a rocket and released on Aug. 11, 2011, was part of research aimed at developing super-fast global strike capability for the Department of Defense.

The vehicle demonstrated stable aerodynamically controlled flight at speeds up to 20 times the speed of sound, or Mach 20, for three minutes before a series of upsets caused its autonomous flight safety system to bring it down in the ocean, DARPA said in a statement.

A gradual wearing away of the vehicle's skin was expected because of extremely high temperatures, but an independent engineering review board concluded that the most probable cause was "unexpected aeroshell degradation, creating multiple upsets of increasing severity that ultimately activated the Flight Safety System," the statement said.

Initial shockwaves created by the gaps in the skin were more than 100 times what the vehicle was designed to withstand, but it was still able to recover and return to controlled flight, said Kaigham J. Gabriel, DARPA's acting director.

Eventually the upsets grew beyond its ability to recover.

The 2011 flight was the second time an HTV-2 was launched. The first flight, in April 2010, also ended prematurely.

Data from that flight was used to correct aerodynamic design models for the second test, resulting in controlled flight, and now data from the latest flight will be used to adjust assumptions about thermal modeling, Air Force Maj. Chris Schulz, the DARPA program manager, said in the statement.

"The result of these findings is a profound advancement in understanding the areas we need to focus on to advance aerothermal structures for future hypersonic vehicles. Only actual flight data could have revealed this to us," he said.

Most specific details of the program are secret. DARPA has released artist renderings showing a craft that looks something like the tip of a spear. After the 2011 flight the agency released handheld video, taken aboard a monitoring ship, that showed a dot streaking across the sky.

The HTV-2 would have splashed down in the ocean regardless of the anomaly. The vehicles are intended to be used once and are not recovered.

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Military loses contact with hypersonic test plane

DARPA’s (Defense Advanced Research Projects Agency) Falcon Hypersonic Technology Vehicle 2 (HTV-2) is shown in this undated artist's conception, released August 11, 2011.

Credit: Reuters/DARPA/Handout

WASHINGTON | Thu Aug 11, 2011 3:22pm EDT

WASHINGTON (Reuters) - An unmanned experimental aircraft designed to glide down from the upper atmosphere at 20 times the speed of sound lost contact with ground control on its second test flight on Thursday, a Pentagon agency said.

The Falcon HTV-2 was launched from Vandenberg Air Force Base in California on a rocket and successfully separated from the launch vehicle, the Defense Advanced Research Projects Agency said.

The arrowhead-shaped plane was expected to separate from the rocket near the peak of its ascent and glide back to earth, reaching hypersonic speed before rolling and plunging into the Pacific ocean, according to a test diagram posted online.

About 10 minutes after the flight began, DARPA tweeted that the mission was "on track, entering glide phase." But about 26 minutes later, DARPA tweeted that its monitoring stations had lost contact with the glider.

"Downrange assets did not reacquire tracking or telemetry," DARPA tweeted about an hour later. "HTV-2 has an autonomous flight termination capacity."

The loss of communications in the final stages of the test flight was a failure for the agency. During the initial flight test in April, researchers lost contact with the vehicle about nine minutes into the flight.

The Falcon HTV-2 glider is part of the Defense Department's effort to build what it calls a "prompt global strike" capability that would enable it to hit targets worldwide within an hour with conventional or nuclear warheads.

(Reporting by David Alexander; Editing by Anthony Boadle)

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