Delta IV

Boeing Company * United Space Alliance

 

The Delta  IV Medium is a large, modular launch vehicle that can launch heavy payloads.  Both core stage are powered by hydrogen and oxygen, making the new design quite different from previous Delta configurations. The new first stage is referred to as the common booster core. Two or four solid boosters GEM-60 (modified Delta III GEMs) can be added in the Medium Plus configurations.
The Delta IV Heavy is a Titan IV class heavy launch vehicle. It consists of a Delta IV core vehicle with two additional common booster core stages used as liquid strap-on boosters. The Delta IV Heavy is capable of delivering spacecraft directly to geostationary orbit.

The Delta IV first stage is a completely new design called the common booster core (CBC). The CBC consists of two large, independent tanks for cryogenic oxygen and hydrogen propellants, and an engine module for the RS-68 engine. The RS-68 is a new, high-performance engine with throttle range (60-100%) and higher thrust than the Space Shuttle main engine SSME. Delta IV uses two second-stage designs, both of which are larger versions of the Delta III stage. The Delta IV-Muses a 13.1- ft. diameter second stage, which has longer tanks than the Delta III version, but is otherwise similar. The Delta IV-H stage has a wider 16.7- ft hydrogen tank, and lengthened LOX tank.
The Delta III 13.1-ft. diameter fairing can  also be used on the Delta IV-M. The Delta IV-M+ and Delta IV-H  use a new 16.4-ft. diameter composite bi-sector fairing. The fairing is available in two lengths, and can be used in conjunction with a dual payload structure.
The Delta IV Medium and Medium Plus configuration will be available beginning in 2001. Another configuration, the Delta IV Small with the Delta II upper stage and their fairing is announced. The maiden flight of the most powerful of the US Air Force Evolved Expendable Launch Vehicle will be delayed to early 2003.

Delta IV Medium
The Delta IV Medium vehicle is built around the CBC first stage and includes the baseline second stage derived from the Delta III, but with stretched fuel and oxidizer tanks for increased performance. This Delta version can lift up to 4,210 kg (9,285 lb) to geosynchronous transfer orbit (GTO). The payload is encapsulated in a 4-m (13.1-ft) diameter fairing for protection.

Delta IV Medium-Plus
Three Delta IV Medium-Plus vehicles use the common booster core and are augmented by either two or four solid rocket strap-on graphite-epoxy motors (GEMs). These vehicles are designated first by the diameter in meters of the upper stage and payload fairing and then by the number of GEMs added to the first stage for boost assist; for example, (4,2).
The Delta IV Medium-Plus (4,2) vehicle uses the same second stage and tanks as the Delta IV Medium. The Delta IV Medium-Plus (5,2) and Medium-Plus (5,4) vehicles use the same engine as the Delta IV Medium, but have larger fuel and oxidizer tanks.
 

Delta IV Heavy
The Delta IV Heavy is designed to lift up to 13,130 kg (28,950 lb) to GTO. It joins three CBCs together for liftoff and uses the larger model Medium-Plus second-stage engine and tanks with a similar 5-m (16.7-ft) diameter payload fairing.