Delta IV/Evolved Expendable Launch Vehicle Program On Oct. 16, 1998, the U.S. Air Force announced the procurement of 19 Boeing Delta IV launches for the Evolved Expendable Launch Vehicle (EELV) program valued at $1.38 billion.
This initial launch services contract covers small, medium and heavy payload class launches from 2002 to 2006. It splits 28 missions in a dual-source procurement designed to encourage greater contractor investment and competition in the U.S. space launch industry, and to decrease the Air Force's overall development cost.
The Air Force also entered into a $500 million agreement with Boeing, supplementing development of the Delta IV family of launch vehicles for meeting all Air Force EELV requirements.
The Boeing Delta IV/Evolved Expendable Launch Vehicle Program (EELV) is a multi-year U.S. Air Force effort aimed at reducing space launch costs by more than 25 percent. To meet these requirements, Boeing is offering the Delta IV family of vehicles. The family includes five launch vehicles: Medium, Heavy, and three variants of the Medium vehicle, known as Medium-plus, which have been introduced to meet the needs of the commercial market.
Program Timing
The EELV program development and procurement cycle began in 1995. During the first phase, four competitors completed a 15-month contract to validate low-cost concepts. In December 1996, two contractors were selected to participate in the second phase, known as the Pre-Engineering, Manufacturing and Development (Pre-EMD) phase, a firm, fixed-price 17-month contract worth $60 million for each company.
In November 1997, the Air Force announced that it intended to introduce competition across the life span of the EELV program, to encourage greater contractor investment and competition in the U.S. space launch industry, and decrease the Air Force's overall development cost.
'''December 13, 2004'''

CAPE CANAVERAL, Florida - The first new heavy lift space vehicle in a generation is cleared to launch from Cape Canaveral Air Force Station. The Boeing '''Delta IV Heavy''' has missed launch opportunities three days in a row (starting Friday, December 12) due to minor technical difficulties. It is now scheduled to launch Dec. 20 or 21 from pad SLC-37B.

The '''Delta 4''' was developed as part of the U.S Air Force's ''Evolved Expendable Launch Vehicle'' program to reduce costs and improve reliability.  The basic design is a two stage, cryogenic LOx/LH2 rocket.  Strap-on boosters may be added to increase lift capacity.  

Two major obstacles have plagued the project in recent years; a bidding scandal which cost Boeing a large portion of the military satellite launch business for which it was competing, and a downturn in commercial satellite launches in 2001.

The ''Heavy'' variant of the Delta 4 rocket can place 13,100 kg (28,950 Lb) into geostationary transfer orbit, greater than any other current rocket. Two additional first stage cores are used as strap-on boosters for this configuration. Their rated thrust is 2,900,000 N (656,000 lb) each. 

Delta 4's main engine, the RS68, is the most powerful hydrogen/liquid oxygen engine in the world, approximately three times as powerful as the Ariane 5 Vulcain HM60. Its design sacrifices efficiency for increased reliability and lower cost: rated specific impulse is 365s at sea level and 410s in a vacuum. The second stage engine, Pratt and Whitney's RL-10B-2, has a specific impulse of 462s.

The primary market for this launcher will be classified spy satellites for the US intelligence community. Most of these satellites were previously launched on the Titan 4, which has since been retired. The Delta 4 Heavy's published launch cost is $170 million, compared to the Titan 4's $400 million (1999 dollars).

Delta 4 Heavy's maiden launch is a demonstration and will carry a dummy load and two nano-satellites. The main payload, dubbed ''DemoSat'' is a 6020 kg (13271 lb) mass designed to simulate the dynamic and initial properties of a real satellite.  Its design consists of large brass rods, intended to fully burn up on reentry.

The two nano-satellites are part of the US Department of Defense ''Nanosat-2 Program'', and built by students from New Mexico State University, Arizona State University, and the University of Colorado at Boulder.