Mercury-Redstone Overview

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Overview of the Marshall Center's Role in Mercury-Redstone Project

(Source Note: The following information is reproduced here as published
in an article prepared by the Marshall Center Public Affairs Office in 1961)

The Mercury-Redstone booster used in the Project Mercury launching was provided and launched for the Space Task Group by the Marshall Space Flight Center, National Aeronautics and Space Administration.
The vehicle is based upon the Army's Redstone which was designed and developed by Marshall scientists and technicians prior to their transfer to NASA. Extensive modifications were incorporated to adapt the rocket to this special role, with major emphasis on increased reliability. The Redstone booster has already achieved a significant record of reliable flight in a launching history which extends over the past seven years. Of the last 40 Redstones launched, only one booster has failed.

Changes in the system for the Mercury mission include the elongation of the tank section to increase fuel capacity, the design of a new instrument compartment and adapter section to accommodate the Mercury spacecraft, changes in engine and the control system in the interest of simplicity, improved reliability and increased performance, and the development of a mission abort system to assure safety of the spacecraft and, on later launchings, its occupant.

The Mercury-Redstone is 83 feet in height, including the spacecraft assembly, compared to the 69 feet of the ordinary Redstone. The body of the rocket is 70 inches in diameter. The lift-off weight is 66,000 pounds including, the one-ton Mercury spacecraft.

Redstone Modifications

Modifications to the Redstone booster include the following:

Tank Section-The rocket's tank section was elongated by about six feet to increase the fuel and liquid oxygen capacity. This will allow fuel sufficient to increase the burning time by some 20 seconds. The Redstone booster was similarly elongated for its role in the launching of the early Explorer satellites. That version of the rocket was known as Jupiter-C.
Engine-The engine used in today's flight was of the latest Redstone engine design (A7), modified for this application. Using alcohol and liquid oxygen, the thrust level of the engine in this launching was 78,000 pounds. Provisions were built into the engine to allow for the extra burning time. There are major improvements in the peroxide system which drives the fuel and liquid oxygen pumps and provides thrust control. The stability of the unit was also improved, and an anti-fire hazard provision was added.
Instrument Compartment-A new instrument compartment (upper section) and spacecraft adapter section were designed for the Mercury flights. The compartment is a pressurized cabin, located between the fuel tanks and the spacecraft, which contains the sensitive control system. Unlike the ordinary Redstone, this compartment does not separate from the booster after burnout; rather it descends to the earth attached to the propulsion unit.
Control System-The Mercury-Redstone, as compared to the Redstone missile, has a well-tested, less complex control system which makes for a simpler and more reliable operation. The system uses an auto-pilot which minimizes the drift during powered flight. Carbon vanes located in the jet exhaust of the propulsion unit coupled with air vanes are used as control surfaces to maintain proper attitude.
Abort system-The abort system, developed by the Marshall Center, serves to give an advance warning of a possible impending catastrophic development — an electric signal which causes the following actions, in sequence; termination of the thrust of booster, separation of the spacecraft from the booster, and activation of the spacecraft's escape rocket which propels the spacecraft to a distance of several hundred feet within one second. The abort system senses and is activated by such conditions as: unacceptable deviations in the programmed attitude of the rocket, excessive turning rates, loss of thrust, critical irregularities of thrust, or loss of electrical power. In addition to the automatic activation when such conditions occur, the escape system could, in a manned mission, be activated by the pilot in the spacecraft, and manually, in the launching blockhouse and at the NASA Mercury Control Center. In this first test of this system, it will not be connected to the spacecraft's escape rocket; instead it will send signals to ground receivers, so that its operation can be monitored.
Instrumentation-Instruments are installed in the rocket to provide and telemeter about 50 measurements surveying all aspects of booster behavior during flight, such as attitude, vibration, acceleration, temperature, pressure and thrust level. These measurements are in addition to the many channels of information which will be telemetered from the spacecraft itself during flight. Several tracking signals are also telemetered by the booster.

Reliability Program

Special emphasis on reliability has been placed in the Mercury Redstone program. Most of the reliability effort was centered on new components - those which are peculiar to the Mercury-Redstone. This program was conducted by the Marshall Center and the Chrysler Corporation. Reliability tests were conducted on individual components, subsystems and systems. Test conditions included excessive vibrations and extreme temperatures. Engineers of the Chrysler Corporation designed and operated a special "rock and roll" test device which subjected the entire instrument compartment of the Mercury-Redstone rocket to environmental stress. This latter phase was devoted primarily to checking out the abort system to assure that it would operate properly on demand and could not be activated accidentally.

Testing At Marshall

Marshall Center personnel ran structural tests on the new Redstone-Mercury configuration which assure the structural integrity of the vehicle. Units of the rocket were submitted to considerably higher stresses and strains than will be encountered in flight.

In addition to the acceptance firing of the engines, the Marshall Center is static firing each completed booster of the Mercury series, prior to their shipment to the launch site. During these static firings a detailed measuring program gives assurance of proper performance of the engine. The Center also captive-fired a complete Mercury-Redstone configuration, including a research model of the spacecraft.

In a grueling survival test, one of the Mercury-Redstone engines was repeatedly captive-fired for a total duration of about 15 times the normal burning time of the rocket. In a final test program, the Mercury spacecraft which was launched today was shipped to the Marshall Center for extensive compatibility tests with the booster under controlled, laboratory conditions. These checks included electrical and mechanical areas, and a long series of checks to exclude the possibility of radio frequency interference between the spacecraft and booster systems. This sequence of check-out; included a simulated countdown, launch and flight, using the same checkout and firing panels which will be used at Canaveral for the actual checkout and launch operations.

Aerodynamics And Trajectory

In the basic design of the Mercury-Redstone vehicle, the Marshall Center conducted special studies, theoretically and by means of wind tunnel models, on the aerodynamic behavior of the new vehicle. The Center also prepared the trajectories to be flown in the Mercury-Redstone series and calculated the safety conditions under which the rocket could be fired at the Atlantic Missile Range.

Launch And Flight Sequence

The Mercury-Redstone takes off vertically. During the first few seconds of burning time, the rocket begins to tilt into a predetermined trajectory. The rocket engine operates for about 140 seconds. Shortly after cutoff, the Mercury spacecraft is separated from the booster (combined tank and engine sections plus the instrument compartment) by the ignition of explosive bolts which release the connecting clamp ring. This is immediately followed by the firing of three small propellant rockets on the base of the spacecraft.

The separation occurs at an altitude of about 35 statute miles. Both the rocket body and the spacecraft continue on separate ballistic trajectories. The spacecraft will land at about 220 statute miles, having reached a maximum altitude of about 130 statute miles. The rocket body should hit the sea some 20 miles beyond the spacecraft.

Industrial Participation

Hundreds of industrial fabricators and suppliers are contributing to the Mercury-Redstone program. The first two of the eight rockets to be provided for Project Mercury by the Marshall Center were assembled at the Center. MSFC also fabricated many of the components; major structural components were manufactured by the Reynolds Metals Company, Sheffield, Alabama. The final six rockets in the series are being furnished to Marshall by the Chrysler Corporation Missile Division, Detroit. Chrysler Corporation also conducted a major reliability program under contract to MSFC. The Rocketdyne Division of North American Aviation Corporation, Canoga Park, California, manufactured the engines for the rockets. Major components of the control system were produced by the Ford Instrument Company, Long Island City, New York, and Sperry-Farragut Company, Bristol, Tennessee, divisions of Sperry-Rand Corporation.

Key Personnel

Dr. Wernher von Braun, as director of the Marshall Center, has overall supervision of the Center's contributions to the Mercury program.

Dr. J. P. Kuettner is the Center's Mercury-Redstone project manager and is responsible for coordinating the effects of the ten Marshall technical divisions in this program. His assistant is Earl Butler. Dr. Kuettner is also a member of the Mercury-Redstone Flight Safety Review Board. Butler serves as the coordinator for the project's Design Panel.

Dr. Kurt H. Debus directs the NASA Launch Operations Directorate, a part of the Marshall Center, which launched the rocket. Dr. Debus also is chairman of the Mercury-Redstone Flight Operations Panel, composed of representatives of the NASA Space Task Group, McDonnell Aircraft and Marshall.