Delta IV Heavy

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.

Quick facts: Function, Manufacturer, Country of origin, Co... ▼

Delta IV Heavy

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	Long March 5 Falcon Heavy Proton-M
Launch history
Status	Production ended
Launch sites	Cape Canaveral, SLC-37B Vandenberg, SLC-6
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	EFT-1 NRO classified payloads Kennen Orion Parker Solar Probe
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
[edit on Wikidata]

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]