Sivb Propellant Tank Structure

JAMB WELD REINFORCEMENT

MECHANICAL FASTENER'

JAMB WELD EXTERNAL DOUBLER (TYPICAL BOTH DOMES)

FORWARD DOME GORE SEGMENT

CHEMICALLY MILLED WAFFLE PATTERN

JAMB WELD REINFORCEMENT

MECHANICAL FASTENER'

JAMB WELD EXTERNAL DOUBLER (TYPICAL BOTH DOMES)

CRYOGENIC

SEALING

COMPOUND

Space Shuttle Main Propulsion Engine

FORWARD DOME GORE SEGMENT

CHEMICALLY MILLED WAFFLE PATTERN

AFT SKIRT ATTACHING RING

THRUST STRUCTURE ATTACHING RING

JAMS WELD INTERNAL DOUBLER (TYPICAL BOTH DOMES)

-LOX TANK SEAL WELD

AFT DOME STRUCTURE

AFT SKIRT ATTACHING RING

THRUST STRUCTURE ATTACHING RING

POLYURETHANE FOAM

JAMS WELD INTERNAL DOUBLER (TYPICAL BOTH DOMES)

CRYOGENIC

SEALING

COMPOUND

-LOX TANK SEAL WELD

AFT DOME STRUCTURE

COMMON BULKHEAD DETAIL

tank structure to the aft interstage. Ullage rockets and the auxiliary propulsion system mount on the aft skirt exterior; electrical equipment panels mount on the skirt interior. The aft interstage assembly is 224.5 in. in length and provides the interface between the S-IVB stage and the S-IB stage. The aft interstage has eight vertical internal reaction beams that translate the loads to the S-IB 220-in. diameter structure points. Four retromotors are mounted externally. The separation plane for the S-IVB stage is the aft end of the aft skirt.

THRUST STRUCTURE.

Figure 5-7 shows the truncated-cone-shaped thrust structure. The configuration of the thrust structure is similar to the skirt assemblies in that 7075-T6 aluminum alloy skin, external stringers, and internal frames are utilized. The structure measures 83 in. high, by 168 in. at the base. The J-2 engine is attached at the small diameter end of the thrust structure through the use of an A-356 aluminum casting. The forward end of the thrust structure is attached to the aft dome of the propellant tank assembly. Electro-mechanical and mechanical systems equipment mounts on the inside and outside surfaces of the thrust structure. Two doors provide access to the thrust structure interior.

LONGITUDINAL TUNNELS.

The longitudinal tunnels (main tunnel and auxiliary tunnel) house wiring, pressurization lines, and propellant dispersion system shaped charges. The tunnel covers are made of 7075-T6 aluminum alloy skin stiffened by internal ribs. These structures do not transmit primary shell loads but act only as a fairing reacting to local aerodynamic loading.

AERODYNAMIC FAIRING.

The aerodynamic fairing on the aft end of the interstage is a short cylinder, 260 in. in diameter, made from eight 7075rT6 corrugated aluminum alloy skin panels. This structure does not transmit primary shell loads but must maintain structural integrity when loaded by local aerodynamic pressure.

PROPELLANT TANK CRYOGENIC INSULATION.

Another design requirement for the propellant tank and common bulkhead is that they provide insulation for the LH 2 tank and in the case of the common bulkhead that it prevent lox freezing due to LH 2 temperatures during a ground hold. Figure 5-8 shows the methods and materials used to provide the necessary insulation for the LH 2 tank. Cross-sections show insulation details of the forward dome, aft dome, forward dome access door, aft dome and common bulkhead area, and cylindrical section and aft dome area. Generally, the insulating tile (a polyurethane foam and fiberglass composite) bonds to the tank skin with an epoxy base adhesive system. In certain areas shown, balsa pads are used in conjunction with tile to line the tank walls with insulating materials. An insulating gap filler material consisting of a glass fiber and polyurethane adhesive composite is used to fill gaps between tiles and around fasteners. Liners consisting of woven glass impregnated with polyurethane adhesive are bonded to the tile and balsa insulating material. In critical areas around brackets and joints the liner is covered by doublers of the same material.

ABLATIVE INSULATION.

Figure 5-9 shows the ablative coating material and the patterns and depth to which it is applied to the external skin of the stage.

S-IVB THRUST STRUCTURE ASSEMBLY

Saturn Drawings
Figure 5-7

FORWARD DOME DEBRIS SHROUD.

A debris shroud surrounds the forward dome of the propellant tank 40.125 in. above the equatorial plane of the dome. Eight nylon cloth shroud segments 9 in. wide by 89 in. long are stitched together with dacron threads and reinforced at their joint with eight nylon cloth splice segments 4 in. by 9 in. The shroud segments are attached to the dome with Velcro tape adhesively bonded to the dome.

RETROROCKET IMPINGEMENT CURTAIN.

A retrorocket impingement curtain is used to shield, at stage separation, the area between the aft dome and aft skirt. The curtain installation spans the area between the aft end of the aft skirt and the engine thruststructurejunction with theaftdome. The basic material used in the construction of the curtain is glass cloth. Tape is used to seal openings in the curtain around boots, slots in aluminum, and other openings.

PROPULSION.

Prime thrust for the S-IVB stage is provided by the main propulsion system, which consists of a bipropellant J-2 rocket engine, fuel system, oxidizer system, tank pressurization systems, engine chill-down systems, and a propellant utilization (PU) system. The J-2 engine, burning lox and LH 2, provides the thrust during the second boost phase of flight to inject the S-IVB stage and payload into orbit. In addition to supplying prime thrust, the J-2 engine provides thrust-vector steering (pitch and yaw) for inflight course correction during powered flight. Command signals from the IU guidance and control system effect the flight steering by hydraulically gim-balling the engine up to ±7 deg from the stage longitudinal axis. The PU system controls the mass of propellants loaded into the stage by providing inputs to the propellant loading system.

The stage propellant tanks consist of a cylindrical section enclosed by hemispherical bulkheads with an internal common bulkhead dividing the structure into fuel and lox tanks. The tank capacity is designed to satisfy an engine mixture ratio of 5 to 1 (oxidizer

+1 0

Post a comment