A big debut

Boeing Delta IV Heavy makes its first flight

BY BOB HOWARD

Boeing employees, customers and other spectators stood and cheered the powerful, new 23-story Delta IV Heavy rocket when it lifted off Dec. 21 in a spectacular display.

The reaction was one of awe as this massive, 232-foot variant of the Delta IV family rumbled off the launch pad from Cape Canaveral Air Force Station, Fla. It was a feat particularly appreciated by those who know their space history and recognized the technical challenges that had to be met for liftoff to occur.

Boeing's impressive demonstration mission was full of successes, with its three Rocketdyne RS-68 engines firing right on the money. Among the milestones achieved were

• Activation and launch from the heavy version of the Delta IV launch pad.
• Flying three interconnected common booster cores.
• Separating the two strap-on common booster cores from the center booster core.
• Flying the first 5-meter-diameter composite payload fairing and separating it from the vehicle.
• Flying the first 5-meter-diameter cryogenic second stage through a longduration, three-burn profile of its RL10B- 2 engine (cryogenic rockets use fuels that change from gas to liquids only at very low temperatures).

The mission purpose was to demonstrate the capability of the Delta IV Heavy ground and flight systems. The flight featured a substantial increase in telemetry measurements over previous first-flight rocket launches. Engineers will use this data to evaluate all aspects of the mission, and validate systems performance to reduce the subsequent risk to flying an operational mission.

"We are very pleased with our overall performance of both the vehicle and the Delta team," said Dan Collins, Expendable Launch Systems vice president. "We've gotten a huge amount of data and positioned ourselves well to move on to the operational missions in 2005."

One unexpected piece of flight data was a premature shutdown of the first stage, resulting in the demonstration payload being deployed to a lower-than-expected orbit. Boeing and U.S. Air Force personnel are working together to determine the cause and expect to solve the problem prior to the first operational flight of the Heavy later this year.

"We have a happy customer, and that feels real good after all the hard work the team put into this vehicle and the demonstration," Collins said. "We are working together with the Air Force and making good progress on understanding all aspects of the six-hour demonstration flight."

The powerhouse behind Boeing's Delta IV Heavy is its combination of three common booster cores, each powered by a Boeing Rocketdyne-built RS-68 engine. Two of the common booster cores are jettisoned during ascent. The added engine power allows the rocket to loft 50,800 pounds (23,040 kilograms) of payload—roughly the weight of four adult African elephants—into low Earth orbit and 28,950 pounds (13,130 kilograms) to geosynchronous transfer orbit, twice the carrying capability of the standard single-core version. In geosynchronous orbit, the payload orbits in synch with the Earth.

The flight of the Boeing Delta IV Heavy means that the United States is well on its way to fielding a powerful new rocket with a lift capability that packs a wallop.

robert.howard@boeing.com