Saturn 1B

Saturn IB

Three launch configurations of the Apollo Saturn IB rocket: no spacecraft (AS-203), Command/Service module (most missions); and Lunar Module (Apollo 5)
Function	Apollo spacecraft development; S-IVB stage development in support of Saturn V; Skylab crew launcher
Manufacturer	Chrysler (S-IB) Douglas (S-IVB)
Country of origin	United States
Size
Height	141.6 ft (43.2 m) without payload
Diameter	21.67 ft (6.61 m)
Mass	1,300,220 lb (589,770 kg) without payload
Stages	2
Capacity
Payload to LEO	46,000 lb (21,000 kg)
Launch history
Status	Retired
Launch sites	LC-37 & LC-34, Cape Canaveral LC-39B, Kennedy Space Center
Total launches	9
Successes	9
Failures	0
First flight	February 26, 1966
Last flight	July 15, 1975
Notable payloads	Unmanned Apollo CSM Unmanned Apollo LM Manned Apollo CSM
First stage - S-IB
Length	80.17 feet (24.44 m)
Diameter	21.42 feet (6.53 m)
Empty mass	92,500 pounds (42,000 kg)
Gross mass	973,000 pounds (441,000 kg)
Propellant mass	880,500 pounds (399,400 kg)
Engines	8 × Rocketdyne H-1
Thrust	1,600,000 lbf (7,100 kN)
Specific impulse	272 seconds (2.67 km/s)
Burn time	150 seconds
Fuel	RP-1/LOX
Second stage - S-IVB-200
Length	58.42 feet (17.81 m)
Diameter	21.42 feet (6.53 m)
Empty mass	23,400 pounds (10,600 kg)
Gross mass	251,900 pounds (114,300 kg)
Propellant mass	228,500 pounds (103,600 kg)
Engines	Rocketdyne J-2
Thrust	200,000 lbf (890 kN)
Specific impulse	420 seconds (4.1 km/s)
Burn time	480 seconds
Fuel	LH2/LOX

The Saturn IB (pronounced "one B", also known as the Uprated Saturn I) was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It replaced the S-IV second stage of the Saturn I with the much more powerful S-IVB, able to launch a partially fueled Apollo Command/Service Module (CSM) or a fully fueled Lunar Module (LM) into low Earth orbit for early flight tests before the larger Saturn V needed for lunar flight was ready.

By sharing the S-IVB upper stage, the Saturn IB and Saturn V provided a common interface to the Apollo spacecraft. The only major difference was that the S-IVB on the Saturn V burned only part of its propellant to achieve Earth orbit, so it could be restarted for trans-lunar injection. The S-IVB on the Saturn IB needed all of its propellant to achieve Earth orbit.

The Saturn IB launched two unmanned CSM suborbital flights, one unmanned LM orbital flight, and the first manned CSM orbital mission (first planned as Apollo 1, later flown as Apollo 7). It also launched one orbital mission, AS-203, without a payload so the S-IVB would have residual liquid hydrogen fuel. This mission supported the design of the restartable version of the S-IVB used in the Saturn V, by observing the behavior of the liquid hydrogen in weightlessness.

In 1973, the year after the Apollo lunar program ended, three Apollo CSM/Saturn IBs ferried crews to the Skylab space station. In 1975, one last Apollo/Saturn IB launched the Apollo portion of the joint US-USSR Apollo–Soyuz Test Project (ASTP). A backup Apollo CSM/Saturn IB was assembled and made ready for a Skylab rescue mission, but never flown.