ALLIED, BOEING BUILDING NEW HYPERSONIC AIRCRAFT $150 MILLION AGREEMENT WITH NASA CALLS FOR THREE 5,000-MPH X-43CS.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - Allied Aerospace and the Boeing Co. announced they will team on the development of the X-43C, an experimental unmanned aircraft intended to fly at close to 5,000 mph.

The two companies will develop the unmanned aircraft under a $150 million, 66-month contract with the National Aeronautics and Space Administration. NASA wants three X-43C vehicles built and flight tested under the program.

The X-43C is a larger version of the X-43A, scheduled to be flight tested early next year. The X-43C will fly at speeds ranging from approximately 3,500 mph to nearly 5,000 mph.

Design and construction is planned from 2003 to 2005, with flight testing in 2007. Flight testing will be conducted by NASA's Dryden Flight Research Center at Edwards Air Force Base.

The X-43 program is aimed at giving researchers information for future space launch vehicles and for ultra-high-speed military and civilian aircraft.

``Hypersonic speeds are really at the edge of our knowledge,'' said Tom Harsha, Boeing Phantom Works X-43C program manager. ``We expect to learn a lot from X-43C that will bring us closer to safe, routine and economical access to space.''

As with the X-43A aircraft, Boeing Phantom Works will lead the effort to develop specific systems for the X-43C, including vehicle design and thermal protection systems along with flight control and navigation systems, the company announced.

The X-43C will be 16 feet long, compared with just over 12 feet for the X-43A. The X-43C also has a different scramjet engine, which uses a hydrocarbon fuel rather than gaseous hydrogen as in the X-43A.

Hydrocarbon fuels are much denser than hydrogen, allowing an engine test time measured in minutes rather than the seconds available with the X-43A, Boeing said.

The goal of scramjet power is to create an ultra-high-speed craft in which engine would get its oxygen for combustion from the atmosphere, rather than carrying the extra weight of its own oxygen as a rocket does.

A scramjet is a high-altitude, very-high-speed version of a ramjet, an engine without traditional jets' whirling fan blades for compressing air to oxidize fuel.

In a ramjet, the fuel is continuously compressed by being rammed into the inlet by the aircraft's high velocity. In a scramjet, the airflow through the whole engine remains supersonic.

By not having to carry oxygen, a spacecraft could save fuel weight and carry more equipment.

For flight tests, the X-43 aircraft will be attached to a Pegasus booster rocket and carried aloft by a modified B-52. The booster/X-43 tandem will be released over the Pacific Ocean.

After the Pegasus booster takes the X-43 to its test altitude of 80,000 feet, the X-43 will separate from the booster and its scramjet engine will fire.

Tests of the X-43A will involve engine burns of about 10 seconds. NASA and the Air Force are working on a larger X-43, dubbed the X-43B, that would use the scramjet engine for up to five minutes.

The X-43C, conceived after the X-43B idea, is envisioned as a steppingstone between the A and B models.

Jim Skeen, [phone]

james.skeen(at)dailynews.com