Delta IV Heavy
Variant of the Delta IV space launch vehicle / From Wikipedia, the free encyclopedia
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The Delta IV Heavy (Delta 9250H) is an expendable heavy-lift launch vehicle, the largest type of the Delta IV family. It is the world's third highest-capacity launch vehicle in operation, behind NASA's Space Launch System and SpaceX's Falcon Heavy and closely followed by CASC's Long March 5.[4][5] It is manufactured by United Launch Alliance (ULA) and was first launched in 2004.[6] ULA will retire the Delta IV Heavy in 2024.[7] As of June 2023[update], one flight remains.
![]() Delta IV Heavy launches from Vandenberg Air Force Base | |
Function | Orbital heavy-lift launch vehicle |
---|---|
Manufacturer | United Launch Alliance |
Country of origin | United States |
Cost per launch | US$350 million [1] NRO: US$440 million |
Size | |
Height | 72 m (236 ft) |
Diameter | 5 m (16 ft) |
Width | 15 m (49 ft) |
Mass | 733,000 kg (1,616,000 lb) |
Stages | 2+ |
Capacity | |
Payload to LEO | |
Mass | 28,790 kg (63,470 lb) |
Payload to GTO | |
Mass | 14,220 kg (31,350 lb) |
Associated rockets | |
Family | Delta |
Comparable | |
Launch history | |
Status | Production ended |
Launch sites | |
Total launches | 15 |
Success(es) | 14 |
Partial failure(s) | 1 |
First flight | 21 December 2004 (USA-181) |
Last flight | 22 June 2023 (NROL-68) |
Type of passengers/cargo | |
Boosters (CBC) | |
No. boosters | 2 |
Height | 40.8 m (134 ft) |
Diameter | 5.1 m (17 ft) |
Empty mass | 26,000 kg (57,000 lb) |
Gross mass | 226,400 kg (499,100 lb) |
Propellant mass | 200,400 kg (441,800 lb) [2] |
Powered by | 1 RS-68A |
Maximum thrust | 3,140 kN (710,000 lbf) |
Total thrust | 6,280 kN (1,410,000 lbf) |
Specific impulse | Sea level: 360 s (3.5 km/s) Vacuum: 412 s (4.04 km/s) |
Burn time | 242 seconds [3] |
Propellant | LH2 / LOX |
First stage (CBC) | |
Height | 40.8 m (134 ft) |
Diameter | 5.1 m (17 ft) |
Gross mass | 226,400 kg (499,100 lb) |
Propellant mass | 200,400 kg (441,800 lb) |
Powered by | 1 RS-68A |
Maximum thrust | 3,140 kN (710,000 lbf) |
Specific impulse | Sea level: 360 s (3.5 km/s) Vacuum: 412 s (4.04 km/s) |
Burn time | 328 seconds |
Propellant | LH2 / LOX |
Second stage (DCSS) | |
Height | 13.7 m (45 ft) |
Diameter | 5.1 m (17 ft) |
Gross mass | 30,700 kg (67,700 lb) |
Propellant mass | 27,220 kg (60,010 lb) |
Powered by | 1 RL10-B-2 |
Maximum thrust | 110 kN (25,000 lbf) |
Specific impulse | 462 s (4.53 km/s) |
Burn time | 1125 seconds |
Propellant | LH2 / LOX |
The Delta IV Heavy consists of a central Common Booster Core (CBC), with two additional CBCs as liquid rocket boosters instead of the GEM-60 solid rocket motors used by the Delta IV Medium+ versions. At lift off, all three cores operate at full thrust, and 44 seconds later the center core throttles down to 55% to conserve fuel until booster separation. The two side boosters burn out at 242 seconds after launch and are separated as the core booster throttles back up to full thrust. The core burns out 86 seconds later, and the second stage completes the ascent to orbit.[3]
The launch vehicle uses three RS-68 engines, one in the central core and one in each booster.[8] On the last seconds of countdown, the hydrogen fuel flows through the engines and upwards along the booster body, and after the ignition that hydrogen inflames, making the characteristic fireball and charred look of the booster.[9]