S-IVB
| S-IVB-206 which was used for the Skylab 2 flight | |
| Manufacturer | Douglas | 
|---|---|
| Country of origin | USA | 
| Used on | |
| General characteristics | |
| Height | 17.81 m (58 ft, 5 in) | 
| Diameter | 6.60 m (21 ft, 8 in) | 
| Gross mass | 271,000 pounds (123,000 kg) | 
| Propellant mass | 241,300 lb (109,000 kg) | 
| Empty mass | 29,700 lb (13,500 kg) | 
| Launch history | |
| Status | Retired | 
| Total launches | 21 | 
| Successes (stage only) | 20 | 
| Other | Restart failure (Apollo 6) | 
| First flight | February 26, 1966 | 
| Last flight | July 15, 1975 | 
| S-IVB 200 series | |
| Powered by | 1 J-2 | 
| Maximum thrust | 200,000 pounds-force (890,000 N) | 
| Specific impulse | 420 s (4.1 km/s) | 
| Burn time | 480 s | 
| Propellant | LH2 / LOX | 
| S-IVB 500 series | |
| Powered by | 1 J-2 | 
| Maximum thrust | 232,250 pounds-force (1,033,100 N) | 
| Specific impulse | 421 s (4.13 km/s) | 
| Burn time | 500 s | 
| Propellant | LH2 / LOX | 
The S-IVB (pronounced "S-four-B") was the third stage on the Saturn V and second stage on the Saturn IB launch vehicles. Built by the Douglas Aircraft Company, it had one J-2 rocket engine. For lunar missions it was fired twice: first for Earth orbit insertion after second stage cutoff, and then for translunar injection (TLI).