astronautix.com Delta IV Large
Family: Delta. Country: USA. Status: Development. 5 m diameter payload fairing.
Specifications
LEO Payload: 25,800 kg. to: 185 km Orbit. at: 28.5 degrees. Payload: 10,843 kg. to a: Geosynchronous transfer, 27deg inclination trajectory. Liftoff Thrust: 884,000 kgf. Total Mass: 733,400 kg. Core Diameter: 5.0 m. Total Length: 70.7 m. Development Cost $: 500.00 million. in 2002 average dollars. Launch Price $: 170.00 million. in 1999 price dollars. Cost comments: Development cost is USAF portion only in cost-sharing arrangement for all Delta IV models. These funds were accompanied by an order for 19 Delta IV launches at a total price of $ 1.38 billion.
Stage Number : 0. 2 x Delta RS-68 Gross Mass : 226,400 kg. Empty Mass : 26,760 kg. Thrust (vac) : 337,807 kgf. Isp : 420 sec. Burn time : 249 sec. Isp(sl) : 365 sec. Diameter : 5.1 m. Span : 5.1 m. Length : 40.8 m. Propellants: Lox/LH2 No Engines : 1. RS-68
2 x Delta RS-68 : 226,400 kg. : 26,760 kg. : 337,807 kgf. : 420 sec. : 249 sec. : 365 sec. : 5.1 m. : 5.1 m. : 40.8 m. Propellants: Lox/LH2 : 1. RS-68 Stage Number : 1. 1 x Delta RS-68 Gross Mass : 226,400 kg. Empty Mass : 26,760 kg. Thrust (vac) : 337,807 kgf. Isp : 420 sec. Burn time : 249 sec. Isp(sl) : 365 sec. Diameter : 5.1 m. Span : 5.1 m. Length : 40.8 m. Propellants: Lox/LH2 No Engines : 1. RS-68
1 x Delta RS-68 : 226,400 kg. : 26,760 kg. : 337,807 kgf. : 420 sec. : 249 sec. : 365 sec. : 5.1 m. : 5.1 m. : 40.8 m. Propellants: Lox/LH2 : 1. RS-68 Stage Number: 2. 1 x Delta 4H - 2 Gross Mass: 30,710 kg. Empty Mass: 3,490 kg. Thrust (vac): 11,222 kgf. Isp: 462 sec. Burn time: 1,125 sec. Diameter: 2.4 m. Span: 5.0 m. Length: 12.0 m. Propellants: Lox/LH2 No Engines: 1. RL-10B-2
'''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.