The Industry Workhorse
Since its introduction in 1989, Delta II has become the industry standard for reliability, on-time delivery of payloads to orbit, and customer satisfaction. The Delta II has launched a multitude of payloads for customers within the United States and around the world including interplanetary satellites for NASA; Global Positioning System (GPS) satellites for the U.S. Air Force (USAF); research and development satellites for the National Reconnaissance Office (NRO), Defense Advanced Research Projects Agency (DARPA) payloads; Missile Defense Agency (MDA) payloads; Earth-observing, science, and communication and imaging satellites for various commercial and international customers. Additionally, the Delta II has provided rideshare opportunities to numerous secondary payloads representing university and international organizations.
The major elements of the Delta II launch vehicle are the first stage with its graphite-epoxy motor (GEM) solid strap-on rocket motors, the second stage, and the payload fairing (PLF). To more precisely satisfy our customer’s needs, the Delta II is available in a number of configurations within the following series: 7300, 7400, and 7900. A four-digit system is used to identify specific Delta II configurations.
The Delta II also has a Heavy configuration employing larger diameter GEM-46 solid strap-on rocket motors on the 7900-series vehicle to further improve the performance. This configuration is designated as 7920H for two-stage missions and 7925H for three-stage missions.
A pillar of the American aerospace industry for more than four decades, the RS-27A is second to none in its class featuring a mature engine design and demonstrated manufacturing processes. The RS-27A is a single-start, fixed thrust liquid bi-propellant gas generator cycle main engine and two vernier engines. In addition to providing vehicle roll control during flight, the vernier engines each contribute more than 1,000 pounds of thrust to the main engine.
Nominal Thrust (sea level): 200,000 lb
Specific Impulse (sea level): 255 seconds
Length: 149 in
Weight: 2,528 lb
Graphite Epoxy Motors
The Delta II 792X vehicle configuration includes nine Alliant Techsystems’ solid rocket GEMs to augment first-stage performance. Six GEMs are ignited at liftoff; the remaining three GEMs, with extended nozzles, are ignited in flight after burnout of the first six. Ordnance for the motor ignition and separation systems is fully redundant. The 732X and 742X vehicles include three or four GEMs respectively, all of which are ignited at liftoff.
In addition to the standard 40-in-diameter GEM that is flown on the Delta II 732X, 742X, and 792X vehicle configurations, the heavier GEM-46 is made available for Delta II Heavy configurations. GEM-46 has a 46-in core diameter and burns approximately 14 sec longer than the standard GEM-40. Both types of GEMs are flown with a fixed nozzle that is canted outboard from the vehicle centerline at 10 degree.
Peak Vacuum Thrust: 145,000 lbf
Total Vacuum Impulse: 7,108,000 lb-seconds
Length: 510 in
Maximum Diameter: 40 in
Weight: 28,600 lb
Burn Time: 62 seconds
Peak Vacuum Thrust: 199,000 lbf
Total Vacuum Impulse: 10,425,000 lb-seconds
Length: 577 in
Maximum Diameter: 46 in
Weight: 42,200 lb
Burn Time: 76 seconds
The second stage is powered by the flight-proven Aerojet AJ10-118K engine. The simple, reliable start and restart operation requires only the actuation of a bipropellant valve to release the pressure-fed hypergolic propellants, with no need for a turbopump or an ignition system. Typical two- and three-stage missions use two second-stage starts, but the restart capability has been used as many as six times on a single mission, for a total of seven burns. During powered flight, the second-stage hydraulic system gimbals the engine for pitch and yaw control. A redundant attitude control system (RACS) using nitrogen gas provides roll control. The RACS also provides pitch, yaw, and roll control during unpowered flight. The guidance system is installed in the forward section of the second stage.
Nominal Thrust: 9,753 lb
Specific Impulse: 320.5 seconds
Fuel/Oxidizer: Aerozine 50/N204
Length: 105.6 in
Diameter (nozzle extension): 60.33 in
Weight: 275 lb
Depending on payload requirements, the Delta II series of launch vehicles offers an optional spin-stabilized third-stage motor. The flight-proven long nozzle Star 48B motor is produced by Alliant Techsystems and uses a high-energy, solid propellant and high-strength titanium cases featuring forward and aft mounting flanges and multiple tabs for attaching external hardware. The submerged nozzle uses a carbon-phenolic exit cone and a 3D carbon-carbon throat. A spin table, containing small rockets, mounts the third stage to the second stage and is used to spin up the third stage prior to separation. The third-stage payload attach fitting mates the third stage with the spacecraft.
Peak Vacuum Thrust: 17,490 lbf
Total Vacuum Impulse: 1,303,700 lbf-seconds
Vacuum Specific Impulse: 292.1 lbf-sec/lbm
Length: 80 in
Diameter (Maximum): 49 in
Weight: 4,721 lb
Burn Time: 84.1 seconds
The Delta II launch vehicle offers the user a choice of three fairings: a 2.9-m (9.5-ft)-diameter skin-and-stringer center section fairing (bisector), and two versions of a 3-m (10-ft)-diameter (bisector) composite fairing with two different lengths. Each of these fairings can be used on either two-stage or three-stage missions. The stretched-length 3.0-m (10-ft) composite fairing, designated 10L, offers more payload volume. The stretched 3-m (10-ft)-diameter composite fairing has a reshaped nose cone and a cylindrical section 0.91 m (3 ft) longer than the standard 3-m (10-ft) version.
Delta II Product CardDelta II Payload Planners Guide