Overview
Manufacturer: United Launch Alliance
Cost: Retired
Stages: 2 (with an optional third)
Height: 38.2 to 39 m (125 to 128 ft)
Diameter: 2.44 m (8 ft)
Mass: 151,700 to 231,870 kgs (334,440 to 511,190 lbs)
Payload capacity (to low earth orbit): 2,700 to 6,100 kgs (6,000 to 13,400 lbs)
Maiden flight: February 14, 1989
Last flight: September 15, 2018
Launch record: 154 successful, 1 partial failure, 1 failure
Variants
Delta 6000: retired
Delta 7000: retired
Delta 7000H: retired
Stage 1
Length: 26.1 m
Engine: 1x RS-27A
Fuel: LOX/RP-1
Thrust: 1,054 kN (237,000 lbf)
Burn Time: 265 seconds
Stage 2
Length: 6 m
Engine: 1x AJ10-118K
Fuel: N2O4/Aerozine 50
Thrust: 43.6 kN (9,800 lbf)
Burn Time: 431 seconds
Stage 3 (optional)
Length: 2 m
Diameter: 1.2 m
Engine: Star 48B
Fuel: HTPB
Thrust: 66 kN (15,000 lbf)
Burn Time: 87 seconds
Boosters
Length: 14.7 m
Diameter: 1.17 m
Engine: GEM-46
Fuel: HTPB
Thrust: 628.3 kN (141,200 lbf)
Burn Time: 75 seconds
Following the Challenger disaster in 1986 and the resulting termination of the Shuttle programme, the US needed a rocket to meet the demand for the launch of commercial payloads. The Delta II launch vehicle was developed by McDonnell Douglas to fulfil that need.
In 1987, the U.S. Air Force signed a contract to purchase seven Delta IIs. A year later, the Air Force exercised additional contract options to purchase a further 20 launch vehicles. On February 14, 1989, the Delta II launch vehicle took its maiden flight launching the Navstar II-1 (USA-35) satellite into orbit.
The original Delta II 6000-series was replaced by the upgraded 7000-series in 1990. Among other improvements, the 7000-series featured the more powerful Rs-27A engine. Following the cancellation of the Delta III, a new Delta II variant, the Delta II Heavy was introduced. The Delta II Heavy featured the cancelled Delta III’s upgraded GEM 46 boosters making it capable of launching significantly larger payloads.
In 1997, McDonnell Douglas merged with Boeing securing the Delta family of rockets for aerospace titan. In 2006, the Delta II became part of United Launch Alliance (ULA), a joint venture between Boeing and Lockheed Martin Space Systems. To date, the Delta II has completed 152 launches suffering just one partial failure and one total failure. The Delta II is, as a result, arguably the most reliable launch vehicle ever produced.
