By Rebecca Rayko,
Farnborough, England - Three derivatives of the Delta IV launch vehicle were unveiled today. The variants of Boeing's next generation heavy launch rocket are aimed for the commercial market, focusing on cost effectiveness over sheer power.
The three configurations of the Delta IV Medium-plus provide both commercial and government customers flexibility over payload ranges. The variants retain the modular design of the original Delta IV model, using a common booster core whose diameter measures roughly the same as a Boeing widebody airplane.
The Medium-plus versions are distinguished by the number of Alliant Techsystems-built solid rocket motors attached to the booster core and the sizes of the upper stages and payload fairings. The latter protect the satellites during the early ascent phases of flight.
The Delta IV Medium-plus family is comprised of:
The variants are powered by the RS-68 engine built by Boeing subsidiary Rocketdyne Propulsion & Power. The engine is capable of 650,000 lbs of sea level thrust.
- Delta IV M+ (4,2) with two solids and a 4-meter fairing for a GTO payload of 5.8 metric tons.
- Delta IV M+ (5,2) with two solids and a 5-meter fairing for a GTO payload of 4.7 metric tons.
- Delta IV M+ (5,4) with four solids and a 5-meter fairing for a GTO payload of 6.7 metric tons.
"We gave up some performance on engines to be able to assemble at a lower cost," Boeing's Tom Parkinson said today. "The Delta IV family is aimed at lowering the cost of launch."
The RS-68 has 95% fewer parts than the Space Shuttle Main Engine, and its design features castings, not weldings, which will result in substantial cost savings, Boeing says.
Boeing predicts there will be 50-60 space launches a year by 2000. The Delta IV variants will enter the market by the second quarter of 2001.