Page 34 - Apollo Moonships

32 On bOard apOllO mOOnships
S–II SECOND STAGE
This Saturn V section was responsible for boosting the rocket once the S-IC first stage was turned off at 38 miles of altitude. The S-II stage was driven by five J-2 rocket engines that supplied 228 000 pounds of thrust each. The engines consumed the propellant of the stage—260 000 gallons of liquid hydrogen (LH2) and 83 000 gallons of LOX contained in two separate tanks, one above the other—in only 395 seconds. In this flight time, the S-II stage propelled its payload to reach 114.5 miles in altitude at a maximum speed of 15,300 mph. The heaviest component of the S-II stage was the thrust structure, a truncated aluminum-alloy cone that supported the five J-2 engines. This segment also housed the major systems of the stage and was protected by a fiberglass heat shield supported by the base of the thrust structure. Other important segments of the Saturn V second stage were the aft interstage, which linked it with the S-IC first stage; and the forward skirt, which attached the S-II section to the interstage forward ring, providing structural support for the S-IVB third stage and its payload.
SATURN V S–IC STAGE CUTAWAY
1 Ullage rocket (4)
2 Interstage aft support ring
3 Interstage ring baffles
4 J–2 engine (5)
5 Engine gimbal point
6 Fiberglass heat shield
7 Instrumentation container
8 Electrical power and control system
9 Aluminum alloy thrust cone
S–II STAGE SIZE
26.0 feet
Interstage forward ring
Forward skirt
Propellant tank
1 2
10 Aft skirt
11 Bottom of LOX tank
12 LOX feed line
13 Cruciform baffle
3
4
10
9
11
8 12 5
13 67
81.5 feet
MAJOR STRUCTURAL COMPONENTS
33 feet
Aft skirt
Interstage aft support ring
18.25 feet
14.50 feet
1 AFT INTERSTAGE
2 THRUST STRUCTURE