Category Apollo Saturn V News Reference

When the cutoff signal is initiated, the LOX dome operational oxidizer purge comes on. and the en­gine control valve stop solenoid is energized. Hy­draulic pressure holding open the gas generator valves, the oxidizer valves, and the fuel valves is routed to return. Simultaneously, hydraulic pres­sure is directed to the closing ports of the gas gen­erator valve, the oxidizer valves, and the fuel valves. The checkout valve is actuated and, as propellant pressures decay, the high level oxidizer purge be­gins to flow: then the igniter fuel valve and the igni­tion monitor valve close. Thrust chamber pressure will reach the zero level at about the same time the oxidizer valves reach full-closed.

WEIGHT: 95,000 lb. (dry)

1,037,0 lb. (loaded)

DIAMETER: 33 ft.

HEIGHT: 81 ft. 7 in.

BURN TIME: 6 min. approx, (actually 395 sec.)

VELOCITY: 15,300 miles per hour at burnout (approx.)

ALTITUDE AT BURNOUT: 114.5 miles

MAJOR STRUCTURAL COMPONENTS

AFT INTERSTAGE THRUST STRUCTURE COMMON BULKHEAD LH2 FORWARD BULKHEAD

AFT SKIRT AFT LOX BULKHEAD LH2 CYLINDER WALLS FORWARD SKIRT

MAJOR SYSTEMS PROPULSION: Five J-2 engines

Thrust: More than 1,000,000 lb. (225,000 maximum each engine)

Propellant: LH2~-260,000 gal. (153,000 lb.)

LOX 83,000 gal. (789,000 lb.)

ELECTRICAL: 6 electrical bus systems, four 28-volt DC flight batteries, and motor-operated power transfer switches ORDNANCE: Provides, in operational sequence, ignition of eight ullage motors before ignition of five main engines, explosive separation of second stage interstage skirt, explosive separation of second stage from third stage, and ignition of four retrorockets to decelerate second stage for complete separation MEASUREMENT: Instrumentation, telemetry, and radio frequency subsystems THERMAL CONTROL: A ground-operated system that provides proper temperature control for equipment containers in the forward and aft skirt FLIGHT CONTROL: Gimbaling of the four outboard J-2 engines as required for thrust vector

control, accomplished by hydraulic-powered actuators which are electrically controlled from signals initiated in the flight control computer of the instrument unit (atop the Saturn V third stage)

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The pneumatic control system provides GHe (gas­eous helium) pressure to operate all third stage pneumatically operated valves with the exception of those provided as components of the J-2 engine. GHe is supplied from an ambient helium sphere and pressurized from a ground source before propel­lant fill operations at 3,100 ± 100 psia at 70° Fahren­heit for valve operation. The sphere is located on the thrust structure and is pre-conditioned to above 70° Fahrenheit from the environmental control system before liftoff.

The pneumatic control system provides regulated pressure at 475 ± 25 psig for operation of the LH, and LOX vent-relief valves during propellant load­ing, LH2 directional control valve, LOX and LH, fill and drain valves during loading, and the GH2 engine start system vent-relief valve. It also pro­vides operating pressures for the LH, and LOX turbopump turbine purge module, LOX chilldown pump purge module control, LOX and LH, pre­valves, LOX and LH, chilldown shutoff valves, and the LH, continuous propulsive vent control module.

The pneumatic control subsystem is protected from overpressure by a normally open solenoid valve controlled by a downstream pressure-sensing switch. At pressures greater than 535 + 15, -10 psia, the pressure switch actuates and closes the valve. At pressures below 450 + 15, -10 psia, the pressure switch drops out and the solenoid opens, thus acting as a backup regulator.

To provide third stage restart capability for the Saturn V, the J-2 gaseous hydrogen start tank is refilled in 60 seconds during the previous firing after the engine has reached steady-state operation. (Refill of the gaseous helium tank is not required because the original ground-fill supply is sufficient for three starts.) Prior to engine restart, the stage ullage rockets are fired to settle the propellants in the stage propellant tanks, ensuring a liquid head to the turbopump inlets.

Also, the engine propellant bleed valves are opened, the stage recirculation valve is opened, the stage prevalve is closed, and a LOX and LH2 circulation is effected through the engine bleed system for five minutes to condition the engine to the proper temperature to ensure proper engine operation.

Engine restart is initiated after the “engine ready" signal is received from the stage. This is similar to the initial “engine ready". The hold time between cutoff and restart is from a minimum of 1-1/2 hours to a maximum of 6 hours, depending upon the num­ber of earth orbits required to attain the lunar window for translunar trajectory.

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The capacity to transport the massive mobile launcher with a fully erected Saturn V in launch ready condition is a key to the mobile concept of Launch Complex 39. This is accomplished by a huge transporter which moves the mobile launcher and vehicle from the VAB to the launch site, approx­imately 3.5 miles away. The transporter moves at a maximum speed of 1 mile per hour, loaded, or 2 miles per hour, unloaded. The vehicle —131 feet long and 114 feet wide—moves on four double­tracked units, each 10 feet high and 40 feet long. Each unit is driven by an electric motor.

Tractive power is provided by 16 direct current motors served by two diesel-driven direct current generators. The generators are rated at 1,000 kilo­watts each and are driven by 2,750 horsepower diesel engines. Speed of the vehicle is controlled by – varying the generator fields. Power for the fields is provided by two 750-kilowatt power units which also provide power for pumps, lights, instrumenta­tion, and communications.

Facility Vehicle at Ramp of Launch Pad

MOBILE SERVICE STRUCTURE

External access to the Saturn V space vehicle at the launch site is provided by the mobile service structure. The steel-truss structure rises more than 400 feet above ground level and more than 350 feet above the deck of the mobile launcher. It has five platforms which close around the vehicle. Two platforms are powered to move up and down. The remaining three are relocatable, but not self­powered. A mechanical equipment room, opera-

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tions support room, communications and television equipment room, and various other equipment com­partments are located in the base.

The service structure is moved to and from the pad by the transporter. Once in position, either at the launch pad or in a parking area, the structure is anchored to support pedestals. The service struc­ture remains in position at the pad until about T-7 hours when it is removed to its parking area 7,000 feet from the pad.

FIRST STAGE DESCRIPTION

The Saturn V first stage (S-IC) is a vertical group­ing of five cylindrical major components and a cluster of five F-l rocket engines. Upward from the engines are the thrust structure, fuel tank, inter­tank structure, LOX tank, and forward skirt. The total stage measures 138 feet in height and 33 feet in diameter without its fins. It weighs 6,100,000 pounds at liftoff and delivers 7.5 million pounds of thrust.

FIRST STAGE FABRICATION AND ASSEMBLY

Design, assembly, and test of the first stage booster are the prime tasks being performed by The Boeing Company at the Marshall Space Flight Center, Huntsville, Ala., the Michoud Assembly Facility, New Orleans, La., and the Mississippi Test Facility in southwestern Mississippi. Launch operations support is provided by the Boeing Atlantic Test

Center, Kennedy Space Center, Fla. Contractor suppliers lend support for much of the first stage fabrication. Several ground test stages were com­pleted before manufacture of a series of flight stages was begun. Huntsville and Michoud installations shared responsibility for assembly of four ground test stages and the first two flight stages. All other flight stages are being assembled at Michoud.

Assembled First Stage

Thrust Structure

The thrust structure is the heaviest of first stage components, weighing 24 tons. It is 33 feet in diam-

Base Assembly—Workmen cover the thrust structure shell with aluminum skin.

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eter and about 20 feet tall with these major com­ponents: the lower thrust ring assembly, the center engine support assembly, four holddown posts, en­gine thrust posts, an upper thrust ring assembly, intermediate rings, and skin panel assemblies.

The upper ring provides stability for the corrugated skins around the structure. Four F-l engines are mounted circumferentially upon the thrust posts and the fifth upon the center engine support assem­bly. The center engine remains rigid while the others gimbal or swivel, allowing the stage to be guided.

A base heat shield protects internal parts from en­gine heat, and four holddown posts restrain the vehicle while the engines build up power for liftoff.

The thrust structure supports the entire vehicle weight and distributes the forces of the engines.

Thrust Structure—The 24-ton base of the booster is being taken to the Vertical Assembly Building for mating with other first stage components.

Fuel Tank

The fuel tank holds 203,000 gallons of kerosene and encloses a system of five LOX tunnels.

The tank, weighing more than 12 tons dry, is cap­able of releasing 1,350 gallons of kerosene per sec­ond to the engines through 10 fuel-suction lines. The LOX tunnels carry liquid oxygen from the LOX tank, through the fuel tank, and to the engines.

Bound by eight aluminum skin panels, the fusion – welded fuel tank assembly is 33 feet in diameter and 44 feet tall. Ends are enclosed by ellipsoidal bulkheads.

The bulkheads consist of eight pie-shaped gores mated with a polar cap to form a dome shape.

Connecting links between the skin rings and bulk­heads are circular bands known as the Y-rings. The Y-rings are used on both propellant tanks and link them to other segments of the booster at final

assembly.

Fuel Tank—Kerosene is fed to the engines at 1,300 gallons per second from this 203,000 gallon tank. Here the finished tank is being lowered onto its transporter.

Inside View—The fuel tank contains horizontal baffles, which are designed to prevent sloshing of fuel.

Fuel Tank Assembly – Workmen weld the base of the 27-inch – high Y-ring to the cylindrical segment of the fuel tank. This ring joins the tank sides to the dome and to the intertank structure.

The first stage film cameras provide photographic coverage of the LOX tank interior during launch, flight, and separation. The stage carries four film cameras. The two LOX-viewing cameras will pro­vide color motion pictures to show the following: behavior of the liquid oxygen, possible wave or slosh motions, and cascading or waterfall effects of the liquid from the internal tank structure. The capsules, which contain the cameras, are ejected automatically about 25 seconds after separation and are recovered after descent into the water. First stage flight versions of the camera consist of the LOX tank-viewing configuration plus two direct-viewing stage separation capsules. The in­stallation is in the forward skirt area. The tank­viewing optical lenses and the two strobe flash light assemblies are mounted in the LOX tank manhole covers. Connecting the remotely located camera capsules and the flash head are the optical assemblies, consisting of coupling lens attached to the ejection tube, a 9-foot length of fiber optics, and the objec­tive lens mounted in the flash-head assembly. The equipment required to complete the system, such as batteries, power supplies, timer, and synchroniz­ing circuitry, is contained in the environmentally controlled equipment racks or boxes mounted around the interior of the forward skirt structure. The combined timer and synchronizing unit serves

two functions. The digital pulse timer supplies real time correlation pulses which are printed on one edge of the film. The timer also supplies event marker pulses to the opposite edge of the film to record selected significant events such as liftoff, engine shutdown, and stage separation. The syn­chronizing unit times the intermittent illumination provided by the strobe lamps to coincide with the open portion of the rotating shutter as it passes the motion picture film gate. The capsule assembly consists of the heavy nose section and quartz win­dow, which protect the capsule during re-entry heating and impact on the water. The body of the capsule, including the camera, is sealed and water­tight. A paraloon and drag skirt aid its descent and flotation. A radio beacon and flashing light are mounted on the capsule to aid in recovery.

TELEVISION SYSTEM
stage separation. The system utilizes two split fiber optics viewing systems and two cameras. Ex­tremes in radiant heat, acoustics, and vibration prohibit the installation of the cameras in the en­gine area; therefore, fiber optics bundles are used to transmit the images to the cameras located in the thrust structure. Quartz windows are used to pro­tect the lens. Both nitrogen purging and a wiping action are used to prevent soot buildup on the pro­tective window.

Image enhancement improves the fiber-optical sys­tems by reducing the effects of voids between fibers and broken fibers. An optically flat disc with paral­lel surfaces rotates behind each objective lens.

The drive motor rotates in synchronism with the master drive motor. A DC to AC inverter energizes the synchronous drive motors. A camera control unit houses amplifiers, fly back, sweep, and other circuits required for the video system. Each vidicon output (30 frames/second) is amplified and sampled every other frame (15 frames/second) by the video register. A 2.5 watt FM transmitter feeds the 7- element yagi antenna array covered by a radome.

SECOND STAGE DESCRIPTION

The second stage of the Saturn V is the most power­ful hydrogen-fueled launch vehicle under produc­tion. Manufactured and assembled by North Amer­ican Aviation’s Space Division, it employs the cryogenic (ultra-low temperature) propellants of liquid hydrogen and liquid oxygen, which must be contained at temperatures of -423 and -297 degrees Fahrenheit, respectively.

For the lunar mission, the second stage takes over from the Saturn V’s first stage at an altitude of approximately 200,000 feet (38 miles) and boosts its payload of the third stage and Apollo space­craft to approximately 606,000 feet (114.5 miles). When its five J-2 engines ignite, the stage is pushing more than one million pounds, a load greater than that of any U. S. booster prior to the Saturn pro­gram. Speed of the stage ranges from 6,000 miles per hour to 15,300 miles per hour.

The beginning of second stage boost is a two-step process. Wien all the F-l engines of the first stage have cut off, the first stage separates. Eight ullage rocket motors located around the bottom of the second stage then fire for approximately 4 seconds to give positive acceleration to the stage prior to ignition of the five J-2 engines. About 30 seconds after the first stage separation, the part of the second stage structure on which the ullage rockets

Mating—A completed second stage is mated to a first stage at Kennedy Space Center, Fla. This particular stage was used for facilities checkout.

are located (the aft interstage) is separated by firing explosive charges. This second separation is a precise maneuver: the 18-foot-high interstage must slip past the engines without touching them. With the stage traveling at great speed, the inter­stage must clear the engines by only a little more than 3 feet.

The second stage burns for about 6 minutes, push­ing its payload into space. At the end of boost, all J-2 engines cut off at once, the stages separate, and the J-2 engine on the third stage begins firing to take it and the Apollo spacecraft into a parking earth orbit. The 81-foot 7-inch second stage is basically a container for its 942,000 pounds of pro­pellant with engines attached at the bottom. Pro­pellants represent more than 90 per cent of the stage’s total weight. Despite this great weight of propellant and the stresses the stage must take during launch and boost, the stage is primarily without an internal framework. It is constructed mostly of lightweight aluminum alloys ribbed in such a fashion that it is rigid enough to withstand the pressures to which it is subjected. Special lightweight insulation had to be developed to kc p its cryogenic propellants from warming and thus turning to gas and becoming totally useless as propellant. The insulation that helps maintain a difference of about 500 degrees between outside (70 to 80-degree normal Florida temperature) and inside (-423° F of liquid hydrogen) is only about 1-1/2 inches thick around the hydrogen tank.

A unique feature of the second stage is its common bulkhead, a single structure which is both the top of the liquid oxygen tank and the bottom of the liquid hydrogen tank. This bulkhead was a critical item in the development of the stage. The relatively thin bulkhead, consisting of two aluminum facing sheets separated by a phenolic honeycomb core insulation, must maintain a temperature difference of 126 degrees between the two sides. The insulation which accomplishes this varies from one-tenth of an inch thickness at the girth to 4-3/4 inches thickness at the apex of the bulkhead. Development of the com­mon bulkhead resulted in a weight saving of appox – imately 4 tons and more than 10 feet in stage length.

The flight control system provides stage thrust vector steering and attitude control. Steering is achieved by gimbaling the J-2 engine during pow-

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ered flight. Hydraulic actuator assemblies provide J-2 engine deflection rates proportional to steering signal corrections supplied by the IU.

Stage roll attitude during powered flight is con­trolled by firing the APS attitude control engines.

DIAMETER: 260 in.

HEIGHT: 36 in.

WEIGHT: 4,500 lb. (approx.)

MAJOR SYSTEMS

ENVIRONMENTAL CONTROL SYSTEM: Provides cooling for electronic modules and

components within the IU and forward compartments of third stage

GUIDANCE AND CONTROL SYSTEM: Determines course of Saturn V through space

and adapts that course to fulfill mission requirements

INSTRUMENTATION SYSTEM: Measures vehicle conditions and reactions during

mission and transmits this information to ground for subsequent analysis,

as well as providing for ground station-to-vehicle communication

ELECTRICAL SYSTEM: Provides basic operating power for all electronic and

electrical equipment in the IU; also monitors vehicle performance and

may initiate automatic mission abort if an emergency arises

STRUCTURAL SYSTEM: Serves as a load bearing part

of the launch vehicle, supporting both the components

within the IU and the spacecraft; composed of three

120-degree segments of thin-wall aluminum alloy face

sheets bonded over a core of aluminum honeycomb

about an inch thick

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num honeycomb. An aluminum alloy channel ring, bonded to the top and bottom edge of each segment, provides mating surfaces between the IU, the third stage, and the payload adapter. Mounted, inner skin brackets provide attachment points for the en­vironmental control system’s cold plates or for cold plate installation.

Segments are aligned and joined by splice plates bolted both inside and outside the joints. A spring – loaded umbilical door provides access to electrical connections between IU equipment and ground test areas. A larger access door, bolted in place, permits personnel to enter the IU after vehicle mating.

Assembly of an IU begins when the three curved structural segments, three feet high by 14 feet long, arrive at IBM’s Huntsville, Ala., facility. Each segment weighs only 140 pounds.

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structure. Components are mounted on the cold plates and ECS system pumps, storage tanks (called accumulators), heat exchangers, and plumbing are installed. Two nitrogen supply systems are installed: one for gas bearings of the inertial platform and the other for pressurization of the ECS. Finally, ducts, tubing, and electrical cables complete the assembly and the IU now weighing in excess of 4,000 pounds is ready for a long series of tests.

The mobile launcher is a movable launch platform with an integral umbilical tower. The launcher base

Arrival to Launch Pad—The facilities vehicle arrives at Launch Complex 39A.

is a two-story steel structure covering more than half an acre. The 380-foot tower, which supports the electrical servicing and fluid lines for the ve­hicle, is a steel structure mounted on the base. The base and tower weigh 10.5 million pounds and stand 445 feet above ground level.

Among major considerations in design of the mobile launcher were crew safety and escape provisions

and protection of the platform and its equipment from blast and sonic damage.

Personnel may be evacuated from upper work levels of the umbilical tower by a high speed elevator, descending at 600 feet per minute. After leaving the elevator, they can drop through a flexible metal chute into a blast and heatproof room inside the base of the pad hardstand.

The mobile launcher provides physical support and is a major facility for checkout of the space vehicle from assembly at the VAB until liftoff at the launch

site.

The top level of the launcher base houses digital acquisition units, computer systems, controls for actuation of service arms, communications equip­ment, water deluge panels, and other control units. Included in the lower level are hydraulic charging units, environmental control systems, electrical measuring equipment, and a terminal room for in­strumentation and communications interface. Mounted on the top deck of the base are four vehicle holddown and support arms and three tail service masts.

The umbilical tower is an open steel structure pro­viding support for nine umbilical service arms, 18 work and access platforms, and, for propellant, pneumatic, electrical, water, communications, and other service lines required to sustain the vehicle. A 250-ton capacity hammerhead crane is mounted atop the umbilical tower.

The launcher restrains the vehicle for approximately 5 seconds after ignition to allow thrust buildup and verification of full thrust from all engines. The design “up-load” during the holddown period is 3 million pounds. If one or more of the engines fail to develop full thrust, the vehicle is not released, and all engines automatically are shut down.

Night Shot—A 365-foot-tall Saturn V facilities vehicle Is shown in place at Launch Pad 39A.

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