Delta IV

Delta IV is a currently active expendable launch system. The system uses rockets designed by Integrated Defense Systems. The rockets are available in five versions: Medium, Medium+ (4,2), Medium+ (5,2), Medium+ (5,4), and Heavy. Each incarnation of the rocket system is tailored to specific payload size and weight ranges.

The rocket’s first stage consists of one to three, Common Boost Cores (CBC) powered by an RS-68 engine. The RS-68 engines burn a combination of liquid hydrogen and liquid oxygen. The primary goal for the RS-68 was to reduce cost from the space shuttle main engine(SSME). The RS-68 engine is mounted to the lower thrust structure of the vehicle by a four-legged thrust frame and enclosed in a composite conical thermal shield. Above this structure is an aluminum isogrid liquid hydrogen tank, followed by the center body, an aluminum isogrid liquid oxygen tank, and a forward skirt.

The upper stage features tanks that are friction stir welded. It is powered by a Pratt & Whitney RL-10B2 engine. This engine offers an extendable carbon-carbon nozzle to improve specific impulse. One of two interstages is used depending on the variant and use. A tapering interstage which narrows down from 5-meters to 4-meters in diameter is used on 4-meter variants, where a cylindrical interstage is used on 5-meter variants.

Guidance, navigation, control, and communication are achieved through an L-3 Communications Redundant Inertial Flight Control Assembly(RIFCA) is similar to those on the Delta II, except with an upgraded software system. The RIFCA features six ring gyroscopes and accelerometers to provide a high degree of reliability.

Delta IV rockets are launched from one of two locations: Space Launch Complex 37(SLC-37) at the Cape Canaveral Air Force Station or Space Launch Complex 6(SLC 6) at Vandenberg Air Force Base. At each location there is a Mobile Service Tower (MST) to provide service access to the rocket and protection from the weather. A crane is used at the top of the MST to load the payload and GEM-60 solid motors. Next to the vehicle is a Fixed Umbilical Tower (FUT), which has multiple swing arms to carry electrical, hydraulic, environmental control, and other support functions to the vehicle through umbilical lines. Beneath the vehicle is a Launch Table, with six Tail Service Masts (TSMs). The Launch Table supports the vehicle, and the TSMs provide further support and fueling functions for the CBCs. The vehicle is mounted to the Launch Table by a Launch Mate Unit (LMU). Behind the Launch Table is a Fixed Pad Erector (FPE), which uses two long-stroke hydraulic pistons to raise the vehicle to the vertical position after being rolled to the pad from the Horizontal Integration Facility (HIF).

We have written many articles about Delta IV for Universe Today.
Delta IV Heavy Blasts off From California
Top Secret: What Did That Delta IV Heavy Take into Space?

If you’d like more info on Delta IV, check out these articles:
Countdown 101: Delta IV
Delta IV Overview

We’ve recorded an episode of Astronomy Cast all about Rockets. Listen here, Episode 100: Rockets.

Source: NASA

Tagged as: Boeing, Delta IV, rockets