VEHICLE CONCEPT
The Saturn IB launch vehicle was conceived in 1962 at the NASA Marshall Space Flight Center as the quickest, most reliable, and most economical means of providing a booster with greater payload capability than the Saturn I. The new launch vehicle would be used for earth orbital missions with the Apollo spacecraft before the Saturn V lunar launch vehicle would be available.
Development of. the Saturn IB was based on a blending of existing designs for the Saturn I and the Saturn V. It uses a redesigned Saturn I booster (designated the S-IB stage), together with the S-IVB upper stage and the Instrument Unit from the Saturn V.
The concept permitted rapid development of a new vehicle. Maximum use of designs and facilities available from the earlier approved Saturn programs, saved both time and costs.
Saturn IB thus becomes a second generation of the Saturn family the first U.S. rocket boosters developed from the start as large payload, manned space launch vehicles.
VEHICLE DESCRIPTION
Saturn IB, including the spacecraft and tower, stands approximately 224 feet tall, and is about 21.7 feet in diameter. Total weight empty is about 85 tons, and liftoff weight fully fueled, will be approximately 650 tons.
First-stage flight is powered by eight H-1 engines generating 200,000 pounds of thrust each, for a total of 1.6 million pounds. In approximately 2.5 minutes of operation, it will burn 41,000 gallons of RP-1 fuel and 66,000 gallons of liquid oxygen, to reach an altitude of approximately 42 miles at burnout. H-1 engines for later S-IB vehicles will be uprated to 205,000 pounds of thrust each.
The S-IVB stage, with a single 200,000 pound thrust J-2 engine, burns 64,000 gallons of liquid hydrogen and 20,000 gallons of liquid oxygen in about 7.5 minutes of operation, to achieve orbital speed and altitude. Thrust of the J-2 will be uprated in later Saturn IB vehicles.
The Instrument Unit is the Saturn IB "brain" responsible for originating electronic commands for stage steering, engine ignition and cutoff, staging operations and all primary timing signals.
Primary payload for the Saturn IB is the Apollo spacecraft which is being developed by NASA for manned flights to the moon. It will be carried atop the Instrument Unit to complete the vehicle's launch configuration.
MISSION
The present Saturn IB program calls for launching 12 vehicles during the 1966-68 period, with the capability to continue at a rate of six to 12 flights per year thereafter. Tests of the complete Apollo vehicle in both unmanned and manned flights are the initial missions assigned.
The first launch, in keeping with the "all-up" philosophy of flight test, will have the first and second stages and the Instrument Unit fully active and will carry a live payload. It will be a ballistic "lob shot" flight designed to test the Apollo heat shield under conditions of high speed re-entry into the earth's atmosphere. The booster will loft the Apollo high above the earth and position the spacecraft in the proper earth reentry attitude. The spacecraft will then separate and fire its service module engines will ignite to drive it back down into the atmosphere to simulate, to a degree, the re-entry after a flight from the moon.
DEVELOPMENT HIGHLIGHTS
Because of NASA's original determination to make maximum use of technology and equipment already existing or under design, Saturn IB has been brought to full development in less than four years after the initial go-ahead decision.
In that time, Marshall Space Flight Center and Chrysler Corporation have completed necessary modifications and uprating on the S-IB stage; Douglas has developed the S-IVB stage for the Saturn IB and accelerated production and testing to meet the launch schedule; MSFC and IBM Federal Systems Division have done the same in adapting the Saturn V Instrument Unit for Saturn IB; and Rocketdyne has uprated the H-1 engines for the S-IB first stage, and stepped up development and production of the J-2 engine for the S-IVB second stage.
The first S-IB booster was test fired at MSFC on April 1, 1965, and subsequently delivered to Kennedy Space Center, Florida, in mid-August.
The second stage for the first Saturn IB flight vehicle was acceptance fired at the Douglas Sacramento Test Center on August 8, 1965, and delivered to KSC on September 19.
The Instrument Unit for the Saturn IB was delivered to KSC on October 20, and mating of the IU and the rocket stages was completed at Launch Complex 34 on October 25. The first Saturn IB flight vehicle was thus completed just 39 months after the initial NASA decision to proceed with its development.
TECHNICAL ADVANCES
Automatic Checkout
Saturn IB is the first major space launch vehicle to employ completely automated, computer-controlled checkout systems for each of its stages. The capability is operational on the S-IVB and the Instrument Unit, and will be used on the S-IB stage for all vehicles after the fourth launch.
The Automatic Checkout System (ACS) uses a carefully detailed computer program and associated electronic equipment to perform a complete countdown checkout of each stage and all its various systems, subsystems, and components.
With electronic speed, it moves through a more thorough and more reliable countdown than is humanly possible. Yet the system permits test engineers to monitor every step of the operation, and to over-ride the computer's functions if necessary.
With electronic signals, the computer tests each item on the extensive check-list programmed into its memory. It compares the response with the result it is programmed to expect.
On receiving a proper response, the computer automatically moves ahead to the next test. But if any tested component fails to respond correctly, the computer automatically indicates the failure at the control console. The machine can pin-point the malfunction for the test conductor. It can also automatically indicate ways to double- check a questionable response, in order to further define any difficulty.
The computer system is used for the final factory checkout of each S-IVB and Instrument Unit. It is used in pre-firing checkouts of the S-IVB before the acceptance test performs the final countdown for the static firing, and controls the actual firing; and it is used again for post-test checkouts.
At Kennedy Space Center, pre-launch checkout and actual launch control functions for the entire Saturn IB also will be computer operated.
The automatic control technology developed for the Saturn program shows promise of significant technical "fall-out" for application in many commercial and industrial applications where rapid, accurate testing of complex equipment is necessary.
J-2 Engine
The J-2 engine which powers the Saturn IB upper stage is the most powerful hydrogen-fueled engine to be developed for flight. It represents a state-of-the-art advance including new systems concepts and significant improvements in many component designs.
Development of a large engine using liquid hydrogen, with a self-integrated control circuit and system, and a self- contained instrumentation assembly, along with stringent requirements for starting and re-starting at altitude with long coast times between starts, required investigation of new areas of circuitry, high-speed rotating machinery, and unique thrust chamber designs.
Control circuits and valves were developed to assure utilization of propellants at maximum efficiency and to permit changing the ratio of oxidizer to fuel in the engine during operation. These not only make it possible to control propellant depletion, but also to vary the engine's thrust by changing the oxidizer-fuel mixture ratio. As the mixture ratio is changed from a nominal 5.0 to a maximum of 5.5 or a minmum of 4.5, thrust varies from about 175,000 to 225,000 pounds.
A pressurized gas sphere is provided for engine start and re-start. It is recharged during test or flight, to remain ready at the proper pressure for re-start. Electrical controls are sequenced during the initial start and burn, in order to re- set the system for another start. The electrical package contains circuitry to permit the re-starting, and engine conditioning controls have been established to provide proper temperature and pressures of the fluids in the engine at the re-start signal.
Significant advances there made in the design of such components as a regeneratively cooled thrust chamber that permits proper cooling at the minimum and maximum flow; an injector that gives optimum performance through the entire thrust range; an axial flow turbopump to feed liquid hydrogen in high volume, and a centrifugal oxidizer pump that is separately operated a gas generator to produce gases for operation of the fuel and oxidizer turbopumps; and new types of insulation and advanced circuitry.
Copyright 1997, 1998 by John
Duncan |