5.7 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Saturn V | 6/10 | https://en.wikipedia.org/wiki/Saturn_V | reference | science, encyclopedia | 2026-05-05T13:12:08.190587+00:00 | kb-cron |
==== Structure ==== The S-IVB consists of the following structural assemblies: the forward skirt, propellant tanks, aft skirt, thrust structure, and aft interstage. These assemblies, with the exception of the propellant tanks, are all of a skin/stringer type aluminum alloy airframe construction. In addition, there are two longitudinal tunnels which house wiring, pressurization lines, and propellant dispersion systems. The tunnel covers are made of aluminum stiffened by internal ribs. The forward skirt, cylindrical in shape, extends forward from the intersection of the liquid hydrogen tank sidewall and the forward dome, providing a hard attach point for the instrument unit (IU). It is the load supporting member between the liquid hydrogen tank and the IU. An access door in the IU allows servicing of the equipment in the forward skirt. The thrust structure assembly is an inverted, truncated cone attached at its large end to the aft dome of the liquid oxygen tank and attached at its small end to the engine mount. It provides the attach point for the J-2 engine and distributes the engine thrust over the entire tank circumference. Attached externally to the thrust structure are the engine piping, wiring and interface panels, eight ambient helium spheres, hydraulic system, oxygen/hydrogen burner, and some of the engine and liquid oxygen tank instrumentation. The propellant tank is cylindrical with a hemispherical dome at each end, and a common bulkhead to separate the liquid oxygen from the liquid hydrogen. This bulkhead is of sandwich type construction consisting of two parallel hemispherical shaped 2014 aluminum alloy domes bonded to and separated by a fiberglass-phenolic honeycomb core. The internal surface of the liquid hydrogen tank is machine-milled in a waffle pattern to obtain required tank stiffness with minimum structural weight. Attached to the inside of the liquid hydrogen tank are: a 10 m (34 ft) propellant utilization probe, nine cold helium spheres, brackets with temperature and level sensors, a chill-down pump, a slosh baffle, a slosh deflector, and fill, pressurization and vent pipes. Attached to the inside of the liquid oxygen tank are slosh baffles, a chill-down pump, a 4.1 m (13.5 ft) propellant utilization probe, temperature and level sensors, and fill, pressurization, and vent pipes. Attached externally to the propellant tank are helium pipes, propellant dispersion components, and wiring which passes through two tunnel fairings.
==== Electrical and instrumentation systems ==== The electrical system of the S-IVB consists of two major subsystems: the electrical power subsystem which consists of all power sources on the stage; and the electrical control subsystem which distributes power and control signals to various loads throughout the stage. On-board power is supplied by four zinc/silver-oxide batteries. Two are located in the forward equipment area and two in the aft equipment area. These batteries are activated during the final pre-launch preparations. Heaters and instrumentation probes are an integral part of each battery. The electrical control subsystem function is to distribute the command signals required to control the electrical components of the stage. The major components of the electrical control subsystem are the power and control distributors, the sequencer assemblies, and the pressure sensing and control devices. The S-IVB instrumentation monitors functional operations of stage systems. Before liftoff, measurements are telemetered by coaxial cable to ground support equipment. During flight, radio frequency antennae convey data to ground stations, similar to the other two stages. The telemetry system consists of a pulse-code-modulator (PCM) digital data acquisition system (DDAS) for pre-launch checkout. The stage also contains a PCM frequency modulated (PCM/FM) system, a FM/FM system, and a single sideband (SS/FM) system for launch information. The radio frequency (RF) subsystem consists of a PCM-RF assembly, bi-directional coupler, RF detectors, DC amplifiers, coaxial switch, dummy load, RF power divider, and associated cabling. Omnidirectional antenna pattern coverage is provided by the folded-sleeve dipoles. The effective radiating power of the system is 20 watts nominal and 16 watts minimum.
=== Instrument unit ===
The Instrument Unit (IU) is a cylindrical structure installed on top of the S-IVB. The IU contains the guidance, navigation, and control equipment. In addition, it contains telemetry, communications, tracking, and crew safety systems, along with their supporting electrical power and environmental control systems. Developed from the Saturn I IU, the Saturn V's IU was designed by the Marshall Space Flight Center and built by IBM at their Huntsville, Alabama facility. The basic IU structure is a short cylinder fabricated of an aluminum alloy honeycomb sandwich material. The structure is fabricated from three honeycomb sandwich segments of equal length. The top and bottom edges are made from extruded aluminum channels bonded to the honeycomb sandwich. This type of construction was selected for its high strength-to-weight ratio, acoustical insulation, and thermal conductivity properties. The cylinder is manufactured in three 120-degree segments, which are joined by splice plates into an integral structure. The access door segment has an umbilical door, as well as an equipment/personnel access door. The access door has the requirement to carry flight loads and still be removable at any time prior to flight. The IU has a diameter of 6.6 m (260 in), a height of 0.91 m (36 in), and a weight of around 2,000 kg (4,500 lb).