Delta III

This article is about the rocket. For the submarine, seeDelta III-class submarine.

Delta III

Delta III rocket diagram
Function	Orbitallaunch vehicle
Manufacturer	Boeing(design, manufacturing and assembly) Mitsubishi Heavy Industries(RP-1 tank and upper stage manufacturing) NASDA(upper stage design) Contraves(fairing and payload adapters)
Country of origin	United States
Size
Height	35 m (115 ft)
Diameter	4 m (13 ft)
Mass	301,450 kg (664,580 lb)
Stages	2 or 3
Capacity
Payload toLEO
Mass	8,290 kg (18,280 lb)
Payload toGTO
Mass	3,810 kg (8,400 lb)
Associated rockets
Family	Delta
Launch history
Status	Retired
Launch sites	Cape Canaveral,SLC-17B
Total launches	3
Success(es)	0
Failure(s)	2
Partial failure(s)	1
First flight	26 August 1998
Last flight	23 August 2000
Boosters –GEM 46
No. boosters	9
Maximum thrust	628.3 kN (141,200 lbf)
Specific impulse	273 seconds (2.68 km/s)
Burn time	75 seconds
Propellant	AP/HTPB/Al
First stage
Powered by	1 ×RS-27A
Maximum thrust	1,085.79 kN (244,100 lbf)
Specific impulse	254 seconds (2.49 km/s)
Burn time	260 seconds
Propellant	LOX/RP-1
Second stage –DCSS
Powered by	1 ×RL10B
Maximum thrust	110.03 kN (24,740 lbf)
Specific impulse	462 seconds (4.53 km/s)
Burn time	700 seconds
Propellant	LOX/LH2
Third stage (Optional) –Star 48B
Maximum thrust	66.723 kN (15,000 lbf)
Specific impulse	286 seconds (2.80 km/s)
Burn time	87 seconds
Propellant	HTPB

Delta IIIwas anexpendable launch vehiclemade byMcDonnell Douglas(later acquired byBoeing). Development was canceled before the vehicle became operational. The vehicle is the third generation of theDelta rocket family,developed from the highly successfulDelta IIto help meet the launch demand of larger satellites. While the Delta III never had a successful launch, some of the technologies developed were used in its successor, theDelta IV.

The Delta III was the first to use theDelta Cryogenic Second Stage,which was designed by theNational Space Development Agency of Japanbased on the second stage it developed for theH-IIArocket and built byMitsubishi Heavy Industries.Contravesbuilt the fairing and payload adapters based on designs it used on theAriane 4.

The first Delta III launch was on August 26, 1998.Of its three flights, the first two were failures, and the third, though declared successful, reached the low end of its targeted orbit range and carried only a dummy (inert) payload. The Delta III could deliver up to 3,810 kilograms (8,400 lb) togeostationary transfer orbit,twice the payload of its predecessor, the Delta II.Under the four-digit designation system fromearlier Delta rockets,the Delta III is classified as the Delta 8930.

History

Due to the continual size and mass growth of commercial satellites in the late 1980s, McDonnell Douglas realized the need for a higher-performance rocket than even their newDelta II.New satellite bus offerings fromHughesrequired a launch vehicle with a 4-meter diameter payload fairing as well as the ability to send 3.5 tons of payload to ageostationary transfer orbit– neither of which Delta II offered.

Multiple options for evolving the Delta II to support larger payloads were considered in the late 1980s and early 1990s, namely using higher-performing liquid hydrogen/liquid oxygen upper stages. Eventually, the Delta III was announced in 1995, boasting an evolved Delta II first stage and a second stage based on that of the JapaneseH-IIrocket. This led to Delta III being similar in size to Delta II, meaning that the existing Delta II infrastructure atSLC-17Bcould be used after some modifications. Soon after the announcement, Hughes placed an order for 13 Delta III launches.

Delta III would only fly three times. The first two launches, both carrying live satellites, ended in failure. The third and final launch, carrying a dummy payload, was only partially successful after the RL-10B second-stage engine shut down prematurely. After commercial interest declined, the Delta III program was officially ended in 2003. Boeing then transitioned their focus to the newDelta IVrocket, which was much more capable than Delta III.

Multiple Delta III rockets were already built and would have been unused, but they were cannibalized for parts for both Delta II and Delta IV.

Description

Delta III was developed from the Delta II rocket. The new vehicle sported a modified first stage and a new, more efficient upper stage. This led to Delta III having around double the payload capacity of Delta II. However, the consecutive failures of the initial Delta IIIs, combined with the more advancedDelta IVprogram and the continuing success of the Delta II, left the Delta III as an interim vehicle.

First stage

Like the Delta II, the first stage of the Delta III burned kerosene and liquid oxygen and was powered by oneRocketdyneRS-27Amain engine with twoLR-101-NA-11 vernier engines for roll control.The vernier engines were also used for attitude control after the main engine shut down, just before the second stage separated.While the propellant load and gross mass of the stage were nearly identical to the Delta II, the diameter of the kerosene tank was increased from 2.4 meters to 4 meters, while its height was reduced. The liquid oxygen tank and engine section remained largely unchanged. The redesigned kerosene tank reduced the overall length of the stage and, combined with the increased height of the second stage, allowed Delta III to use the same launch facilities as Delta II with only minor modifications.

The first stage thrust was augmented by nineGEM-46 solid rocket boosters, sometimes referred to as GEM LDXL (Large Diameter Extended Length). These were 14.7 m (48 ft) meters in length, 1.2 m (46 inches) in diameter, and had a mass of 19 metric tons each, about six metric tons more than the Delta II's standard GEM-40 motors. Six were ignited on the launch pad, while the remaining three were ignited just before burnout and separation of the ground-lit boosters. To maintain steering authority, three of the ground-lit boosters hadvectoring nozzles.GEM-46 boosters would later find use on Delta II, creating the Delta II Heavy variant.

Delta Cryogenic Second Stage

A Delta IIIDCSS upper stageundergoing testing atPlum Brook Field Stationin January 1998

The second stage of the Delta III was the newly developedDelta Cryogenic Second Stage(DCSS), which burned liquid hydrogen and liquid oxygen. It was developed and manufactured partly by Mitsubishi Heavy Industries and was based on the second stage ofJAXA's H-IIA rocket. Boeing was in charge of preliminary design and the development of new technologies, while Mitsubishi Heavy Industries was responsible for manufacturing. The liquid hydrogen tank was 4 m (13 ft) meters in diameter while the separate liquid oxygen tank (attached by a truss to the bottom of the hydrogen tank) was around 3 m (9.8 ft) meters in diameter. This stage offered significantly better performance than the Delta II's second stage, theDelta-K,which burned hypergolic propellants.The DCSS was powered by aPratt & WhitneyRL10B-2 engine, derived from the RL10 powering theCentaurupper stage but featuring electromechanical actuators for gimbal control and an extending nozzle for increased performance.After Delta III's retirement, the DCSS design was modified for use as the Delta IV's second stage in both the original 4-meter diameter form factor as well as a larger 5-meter diameter stage.A further refinement of the 5-meter diameter DCSS, known as the Interim Cryogenic Propulsion Stage, is used on the Block ISpace Launch Systemrocket.

Control of the second stage was provided by 4 sets of hydrazine thrusters installed around the bottom of the liquid oxygen tank. During engine burns, these thrusters only provided roll control (as the engine itself could gimbal for pitch and yaw). During coast periods, these would then provide 3-axis control.

Star 48B third stage

Delta III was offered with an optional Star 48B solid-fueled third stage. It would have been attached on top of the DCSS and contained inside the payload fairing. The Star 48B would have been used for high-energy orbits, like geostationary or interplanetary missions.It was never flown on Delta III but was commonly used on Delta II missions. The Star 48B has also seen use on Delta IV and Atlas V.

Payload fairing

Delta III's payload fairing was a newcompositedesign, matching the upper stage hydrogen tank's 4 m (13 ft) diameter and allowing larger payloads than the Delta II's 9.5 or 10-foot-diameter fairing. Delta III's 4-meter fairing was derived from Delta II's 10 ft composite fairing.This fairing design would later be repurposed on the Delta IV Medium.

Launches

Flight Number	Date / time (UTC)	Rocket Configuration	Launch site	Payload	Payload mass	Orbit	Customer	Launch outcome
1	August 27, 1998 01:17	Delta III 8930	CCAFS SLC-17B	Galaxy 10	700 kg (1,500 lb)	GTO	PanAmSat/Intelsat	Failure
	Maiden flight of Delta III. Destroyed by range safety after control problems and depletion of hydraulic fluid.Communications satellite.
2	May 5, 1999 01:00	Delta III 8930	CCAFS SLC-17B	Orion 3	4,300 kg (9,500 lb)	GTO	Loral	Failure
	Second stage engine failure. Payload placed inlow Earth orbit,declared too low andLoralcalled satellite lost. Communications satellite.
3	August 23, 2000 11:05	Delta III 8930	CCAFS SLC-17B	DM-F3	4,383 kg (9,663 lb)	GTO	US Air Force	Partial failure
	Reached lower than planned orbit. Final flight of Delta III.DemoSat.

See also

• Comparison of orbital launchers families

External links

• History of the Delta Launch Vehicle
• Spaceflight Now article 8/21/2000