Delta IV

The 21st Century Launch Solution

Delta IV

The Delta IV family of launch vehicles combines design simplicity, manufacturing efficiency, and streamlined mission and vehicle integration to meet customer requirements to launch high-priority U.S. Air Force (USAF), National Reconnaissance Office (NRO), NASA, and commercial payloads to orbit.

With operational launch pads on both coasts—Space Launch Complex-37 at Cape Canaveral Air Force Station, Fla., and Space Launch Complex-6 at Vandenberg Air Force Base, Calif.—every Delta IV configuration is available to service the requirements of current and future satellite programs.

The Delta IV launch system is available in five configurations: the Delta IV Medium (Delta IV M), three variants of the Delta IV Medium-Plus (Delta IV M+), and the Delta IV Heavy (Delta IV H). Each configuration is comprised of a common booster core (CBC), a cryogenic upper stage and either a 4-m-diameter or 5-m-diameter payload fairing (PLF).

There are three variants of Delta IV M+ configuration. The Delta IV M+(4,2) uses two strap-on solid rocket motors (SRMs) to augment the first-stage CBC and a 4-m diameter PLF. The Delta IV M+(5,2) and Delta IV M+(5,4) have two and four SRMs, respectively, and 5-m-diameter PLF.

The Delta IV Heavy employs two additional CBCs as strap-on liquid rocket boosters (LRBs) to augment the first-stage CBC and 5-m-diameter PLF.


Main Engine

Design simplicity, demonstrated capability and cost-efficiency define the RS-68A, the main engine for the Delta IV. Designed and manufactured by Pratt & Whitney Rocketdyne, the throttleable RS-68A engine is the largest existing hydrogen-burning engine. Conceived using a simplified design approach, the resulting engine requires 80 percent fewer parts than the Space Shuttle main engine, is lower risk, has reduced development and production costs and has inherently reliable operation.

Nominal Thrust (sea level): 702,000 lbs

Specific Impulse (sea level): 362 seconds
Length: 204 in
Weight: 14,876 lbs
Fuel/Oxidizer: Liquid Hydrogen/Liquid Oxygen

Solid Rocket Motors

For missions requiring additional thrust at liftoff, the Delta IV M+ configurations use either two or four Alliant Techsystems-manufactured solid rocket motors (SRM). Separation is accomplished by initiating ordnance thrusters that provide a radial thrust to jettison the expended SRMs away from the first stage.

Peak Vacuum Thrust: 280,000 lbf
Specific Impulse: 275.2 seconds
Length: 636 in
Maximum Diameter: 60 in
Weight: 74,500 lbs
Nominal Burn Time: 90 seconds

Second Stage

Both the Atlas and the Delta IV second stages rely on the RL10 propulsion system to power their second stages. Logging an impressive record of more than 385 successful flights and nearly 700 firings in space, RL10 engines, manufactured by Pratt & Whitney Rocketdyne, harness the power of high-energy liquid hydrogen and boast a precision control system and restart capability to accurately place critical payloads into orbit.

The Delta IV employs the RL10B-2 with the world’s largest carbon-carbon extendible nozzle.

Nominal Thrust: 24,750 lbs
Specific Impulse: 465.5 seconds
Fuel/Oxidizer: Liquid Hydrogen/Liquid Oxygen
Length: 86.5 in (stowed); 163.5 in (deployed)
Diameter (nozzle extension): 84.5 in
Weight: 664 lbs

Payload Fairings

The fairings protect the payload from encapsulation through the boost phase of flight.

The 4-m-diameter by 11.7-m (38.5-ft)-long fairing is a composite bisector design and is used on the Delta IV M and M+(4,2).

The 5-m-diameter composite fairing also is a bi-sector design and comes in two standard lengths. The 14.3 m (47 ft) fairing is used on the Delta IV M+(5,2) and M+(5,4). The 19.1 m (62.7 ft) fairing is used on the Delta IV Heavy.

The 5-m metallic trisector fairing (the baseline for heritage government programs) is a modified version of the flight-proven Titan IV aluminum isogrid fairing designed and manufactured by The Boeing Company.

All PLFs are configured for off-pad payload encapsulation, which enhances payload safety and security and minimizes on-pad time.


MediumM+ (4.2)Heavy
GTO4,210 kg
(9,280 lbs)
6,160 kg
(13,580 lbs)
13,810 kg
(30,440 lbs)
LEO9,190 kg
(20,250 lbs)
12,900 kg
(28,440 lbs)
28,370 kg
(62,540 lbs)

Atlas V and Delta IV Technical Summary

Delta IV User's Guide

Delta IV Heavy Cutaway

Delta IV 4-meter Cutaway

Delta IV 5-meter Cutaway