The Evolved Expendable Launch Vehicle Program (EELV) is a multi-year U.S. Air Force program aimed at reducing space launch costs up to 50 percent from today’s rate of approximately $12,000 per pound of payload to orbit. The program includes three classes of launch vehicles--Small (4,800 pounds to geosynchronous transfer orbit (GTO)), Medium (10,000 pounds to GTO) and Heavy (33,000 pounds to GTO). To meet these requirements McDonnell Douglas is designing the Delta IV family of launch vehicles.
The Air Force selection of two contractors in December 1996 moved McDonnell Douglas and Lockheed Martin forward to Module II of the EELV program, Pre-Engineering, Manufacturing and Development (Pre-EMD). Pre-EMD is a firm fixed-priced 17-month contract worth $60 million for each company. The final module, EMD, is a winner-take-all to develop the EELV family with the first test flight in 2001. The EMD contract value is $1.4 billion.
All Delta IV configurations share a common booster core (CBC), a new low-cost design that is optimized for high-performance, environmentally compatible liquid oxygen/liquid hydrogen fuel. In the Delta tradition of high reliability, the CBC features a single booster engine. The three configurations are; (1) Delta IV-Small CBC, proven Delta II hypergolic upper stage, optional Delta II third stage, and Delta II 10-ft diameter composite fairing; (2) Delta IV-Medium CBC, Delta III upper stage, and Delta III 4-m fairing; and (3) Delta IV-Heavy CBC, 2 strap-on CBCs, Delta III upper stage with extended tanks, Titan IV 200-in. fairing. Common across all is the Delta family suite of fault-tolerant avionics, flight-proven core software, and standardized launch pads, facilities, equipment, and processes.
The three configurations are designed to meet the National Mission Model payload and performance requirements. These vehicles span the mass-to-orbit requirements for government and commercial spacelift, now and into the future. In addition, consistent Delta reliability and launch responsiveness will ensure a continuous and growing commercial market for Delta IV for sustainable cost savings to the government. Delta IV is sized to accommodate geosynchronous transfer orbit (GTO) loads greater than any existing launch system, at substantially lower cost. We have matched payload weights to each configuration with appropriate margin for growth resulting in a design that balances performance with cost.
Key to the McDonnell Douglas entry is development of a revolutionary low-cost engine design by the Rocketdyne Division of Boeing North American, Inc. The RS-68 burns liquid oxygen and liquid hydrogen that produces a dramatic 30 percent gain in performance over conventional liquid oxygen and kerosene-fueled engines. The design for all three Delta IV variants uses this new 650,000-pound-thrust common booster core engine. Designed to the low end of LO 2 /LH 2 performance, the RS-68 engine does not rely on new technology, exotic materials, or tight-tolerance manufacturing processes. The RS-68 uses fewer parts (7% of the Space Shuttle Main Engine), a conventionally fabricated coaxial injector, low-speed single-stage centrifugal turbopumps, a low-pressure chamber design evolved from the J-2, and an available bolt-on nozzle. A major main engine component was successfully tested October 31, 1996 at NASA's Marshall Space Flight Center in Huntsville, AL, when liquid oxygen and hydrogen were ignited in the thrust chamber of the RS-68 main booster engine.
Delta II or III upper stages, evolved over decades of reliable Delta service, are added to the common booster core to complete each vehicle. For example, the Delta IV Small rocket adds the Delta II second stage, optional third stage and 10-foot-diameter composite fairing. The Delta IV Medium adds the cryogenic second stage engine of the Delta III, now in development, and the Delta III composite, 13.1-foot-diameter fairing for payload protection. The proven McDonnell Douglas-built Titan IV fairing and a modified Delta III second stage would be incorporated on the Delta IV heavy.
Launch preparations and testing will take place at Cape Canaveral Air Station, Fla., and at Vandenberg Air Force Base, Calif. A new launch pad, mobile service tower and horizontal integration facility will be built at Space Launch Complex 37 at Cape Canaveral to handle launches. Space Launch Complex 6 at Vandenberg will be modified for Delta IV launches. Both sites will process rockets horizontally, away from the launch pad, to reduce pre-launch on-pad time from 24 days to only six-to-eight days.
To lower cost and increase flexibility, Delta IV is integrated horizontally in a dedicated facility at each launch site. This facility can support the integration of several Delta IVs simultaneously. Mobile elevated platform transporters to move vehicle stages around the launch site, and in the integration facility to mate CBCs and upper stages. The transporters save time and personnel costs, and eliminate hazardous crane operations for core vehicle buildup. Horizontal processing of launch vehicles takes less than one-half the time of vertical processing.
Major subcontractors for the Delta IV include:
