Air University Review, March-April 1968
The design, construction, and operation of missile real property and real property installed equipment established several records: they were the first Air Force facilities designed to protect against the effects of nuclear weapons; the first major program to employ the concept of concurrency; the first mass installation of sophisticated systems by advertised construction contracts; the first mating of off-the-shelf real property installed equipment with sophisticated missile hardware; and the first time the Civil Engineer participated in the direct support to a weapon system.
Real property (RP) includes any right, title, or interest in land, buildings, fixed improvements, utility, and other permanent addition to land.
Real property installed equipment (RPIE) is defined as those items of government-owned accessory equipment, apparatus, and fixtures which aid in the function of real property and are permanently attached to, integrated into, built in or on government-owned or -leased property, including air-conditioning systems and equipment.
The role of the Air Force Civil Engineer is to design, construct, operate, and maintain that RP/RPIE necessary for the operation and maintenance of any weapon system and for the shelter of men, materiel, and equipment.
The evolution of missiles and missile facilities was an excellent example of the tremendous rate of growth in pure science and technology in the early 1950s. Although the effectiveness of the atom bomb was dramatically demonstrated in terminating the hostilities of World War II, the degree of its effectiveness and the reliability of its design remained to be established. Early testing began necessarily with small weapons in the kiloton range, to verify bomb design and to ascertain the magnitude. Protective construction against the effects associated with nuclear weapons involves a specialized field of engineering which was developed by integrating the sciences of seismology, geophysics, and dynamics and related civil, structural, electrical, mechanical, and other engineering disciplines. Preliminary studies in the design of protective construction were predicated on the results of the early tests. As testing techniques and instrumentation were improved, higher-yield weapons were developed with significantly longer durations, which negated much of the early design. Structural components rather than complete structures were then dynamically loaded in simulated tests using Primacord. In this way confidence was established in the design’s capability to withstand effects of higher overpressure levels.
With the advent of Sputnik in the fall of 1957, the urgent need for operational missiles dictated expeditious action. Finally selected as the most feasible method of providing operational missiles at the earliest possible date was the concept of concurrency, whereby missiles and missile components were designed, developed, and fabricated concurrently with the design and construction of supporting facilities. To the structural engineer, the greatest challenge is in the unusually high design loads, dynamically applied. Normally, loading is expressed in pounds per square foot. In protective construction, the same numerical loading in pounds per square inch may be required. These great loadings also influence foundation design in protective structures.
Conventional structures are free standing, bearing only on the ground through foundations, footings, or piling. With dynamic loading, underground structures like missile silos can bear against the soil in any direction. In fact, the tremendous energy generated by design overpressures must be resisted not only by the maximum allowable deflection of a structure but by that of the surrounding soil/rock as well. Since there is no uniform soil/rock in nature, variations encountered at the different sites complicate the analysis of soil interaction with structures. The interrelationship between structures and soil/rock is typical of the extra effort required in designing protective construction.
Conventional facilities are designed to withstand a G-force of unity, plus a small fraction of a G-force for earthquake areas. Hardened facilities must be designed for many G-forces. The selected shock spectrum depends on the size of the weapon, the overpressure, the type of soil/rock, and the materials of construction. Not only must the structures be designed to survive severe conditions, the sophisticated electrical, mechanical, communications, and electronic equipment must also be protected.
The magnitude of shock platforms and the design shock spectrums used for missile facilities were unprecedented. Consider a fully loaded missile, two large diesel generators complete with an electrical distribution system, an air-conditioning system with standby chillers, large fuel, water, and pneumatic tanks, control systems, black boxes, and numerous other equipment installed in an eight-story structure about 45 feet in diameter. Now consider the structure, mounted on a special trailer, traveling down a very rough road at high speed. The ensuing motion is indicative of the displacement, velocity, and accelerations encountered not only in a single degree of motion but in multiple degrees of motion as well. In a conventional structure the deflection of a beam is so small that, for all practical purposes, the floor it supports is considered level. In protective construction it is sometimes necessary to use very large beams as springs. That the earth and entire structures under design conditions literally move many inches is hard to comprehend.
Prime power for a weapon system as numerous and as widely dispersed as Minuteman presents many problems, not only in the original design but in operation and maintenance as well. Dozens of power sources are involved, each tailoring its respective power transmission to suit the area served and the prevailing weather conditions. Power transmission systems vary from the bare minimum systems in remote, sparsely settled areas to good systems in areas which have reasonably high demands. Blinking lights and frequent power outages during storm periods are accepted in remote areas because it is not economical for power companies to double the number of poles and add other desirable appurtenances. Under these circumstances, the government could not economically contract for power other than what was available at each site. Missile power systems had to be designed accordingly. Some sources had Delta-Y power connections and some had Y-Y power connections. Although either power source is acceptable, power sensing controls to start prime diesel power upon commercial power failure had to be mated into the connected systems.
Missile facilities are comprised of many integrated structural, mechanical, and electrical systems that house the missile and provide power, environment, and fuel. Many of these systems are hazardous because of either the fluids used or the operating pressures needed to actuate massive silo doors. First-generation missiles like the Atlas series and Titan I were fueled with RP-4 (a jet type of fuel) and liquid oxygen, stored and handled under cryogenic conditions. Large, high-pressure hydraulic systems were required to actuate the massive silo doors, elevators, operating platforms, etc. The large amounts of inert gases required to fuel and defuel missiles during launch exercises were stored at high pressure. Leakage and escape of inert gases present no problem in the open but can be hazardous to life in the confined space of a silo should the ventilating system malfunction or fail.
The potential danger of a mishap to a fully loaded missile during exercise or launch necessitated special precautions. The launch control centers were designed to resist not only the effects of nuclear weapons but also the effects of an accidentally ignited missile loaded with fuel in a silo, since the amount of fuel which first-generation missiles burn in four minutes is about equal to that a modern jet liner burns in a cross-country flight. In addition, intercontinental ballistic missiles are not air breathers and have to carry their own oxidizer, another potential hazard.
Hazards inherent in the construction, installation, and checkout of missile facilities required special safety programs. Special knowledge required to safely construct the exotic systems on a massive scale was obtained by contracts with specialists in the respective fields. Once this knowledge was available, it had to be disseminated to and assimilated by not only the contractors and their workmen but government inspectors and engineers and finally by the operating personnel. Precautions had to be taken. For instance, in the fabrication of valves, fittings, piping, tanks, etc., for handling liquid and gaseous oxygen, it was necessary to establish clean rooms and cleanliness standards exceeding those for hospital operating rooms and pharmaceutical manufacturers. Cleanliness had to be enforced in the field, too. During installation and checkout of oxygen systems, pipe fitters wore white coats, and the entire area was maintained at a degree of cleanliness never before attained for conventional construction. The hypergolic fuels of Titan II, although not as dangerous as liquid oxygen, required special handling because of the inherent danger of toxicity and of spontaneous combustion.
Almost every engineering discipline used in the design and construction of missile facilities required the integration of at least one other engineering discipline. Orienting the many agency offices, designers, contractors, and inspectors involved in the programs with the dynamic characteristics of protective construction was no little accomplishment. The standard government procedure for constructing facilities is the formal advertised contract method, designed to encourage maximum competition, resulting in lowest cost. Any RP/RPIE construction and supply items that can be adequately described by plans and/or specifications are subject to this practice.
For uniformity and standardization of operating procedures and repair parts, many component parts of missile support equipment were purchased in advance by the government for an entire wing under separately advertised contracts and then furnished to the construction contractor or the installation and checkout contractor for installation. Less important components were included in and furnished and installed under the construction contract.
In the expedited construction of a single conventional facility, it is not uncommon for designers to be two weeks ahead of construction crews. Under the concept of concurrency, the partially constructed missile facilities had to be changed as dictated by breakthroughs in missile development. Whereas usually only one facility is involved in conventional construction, up to 200 identical facilities were involved in any one missile construction contract. The concept of concurrency was necessarily expensive, but it was a price that had to be paid for earliest possible missiles.
The number of people proficient in the design, construction, and handling of exotic and complicated missile facility systems was limited. Many of these systems, usually small in size, were designed and constructed almost on a proprietary basis.
Inspection has always been important in construction work, and structures peculiar to protective construction introduced new problems for the inspector. The space surrounding a shock-mounted structure inside a silo to allow for movement under design conditions is referred to as rattlespace. Construction drawings, unlike shop drawings, can show only so much detail. If equipment, pipes, conduits, etc., encroach into this rattlespace, these components could be damaged by being crushed against the concrete silo walls under design movement and the missile rendered ineffective. These oversights may seem simple and inexcusable, but we must consider the conditions under which this work was accomplished. Building tradesmen were not accustomed to working on swaying floors, so it was necessary to crib the shock-mounted platforms. If the cribbed platforms were not accurately positioned or maintained, rattlespace dimensions would have to be adjusted accordingly. The same was true if a contractor furnished an “equal” unit of significantly different shape from that designed. Although every effort was made to ensure that all missile facilities were uniform in every wing, slight variations peculiar to construction were inevitable. It is practically impossible to build dispersed facilities to the same degree of uniformity possible on a production line.
Indicative of the sophistication associated with missiles is the fact that the air-conditioning systems must operate 24 hours a day every day in the year to maintain missiles in ready-to-launch condition. Under the concept of concurrency, specifications had to be prepared in many offices. Unfortunately, all specification writers did not call for the same degree of dependability, which in the case of RPIE usually means that the unit has been manufactured for at least five years. This period allows a manufacturer to work out the bugs and develop the desired dependability.
Construction materials and equipment are continually being changed to incorporate new materials and improved manufacturing procedures. In the normal development of a weapon system, testing in prototype installations would prove or reject these equipment components; but in the absence of prototype testing, quality control and reliability factors were minimized in the real property installed equipment furnished by the construction contractor. Causative factors were specification requirements and available time.
It was anticipated that the large number of like facilities would introduce mass construction methods, such as special boring equipment to excavate for silos, in the interest of economy. Apparently, the construction schedule did not permit the time necessary for development of special equipment, for much conventional construction equipment was used instead. One contractor did introduce an innovation in constructing the facilities for two wings of a first-generation missile. Soil conditions at the sites enabled him to excavate to the bottom level of the silos with large earthmoving equipment. All structures were then constructed above ground, and the soil was backfilled around them. In subsequent operation and maintenance of the facilities, however, some settling became evident.
Under the 375 series of Air Force regulations, the Civil Engineer is required to maintain real property/real property installed equipment in support of a weapon system. Since the advent of missiles, this support has included actual operation and maintenance of certain items of real property installed equipment directly connected to a missile.
Support of missiles, officially referred to as aerospace vehicle equipment (AVE), and missile ground equipment not RP/RPIE, officially referred to as aerospace ground equipment (AGE), is covered in the 67 series of Air Force manuals and regulations. Support of weapon systems hardware has been developed to a fine art through years of experience. Repair parts for missile AGE and AVE are requisitioned, shipped, stocked, and procured automatically by electronic data-processing equipment. Similar procedures are used to program for supply funds to procure repair parts.
RP/RPIE construction is under conventional advertised contracts. Maintenance, repair, and construction are covered in the 85 series of Air Force manuals and regulations. Under the operation and maintenance (O&M) program, repair parts for diesel generators, airconditioning systems, etc., in direct support of a missile system vie for the same dollars that are used to replace floor covering, painting, and other routine maintenance and repair work. Although missile support is assigned a high priority, the support is provided at the expense of the O&M program, which is already overtaxed. Every year more facilities are being operated and maintained with less funds and fewer people. Funds to support missile AGE are programmed through Air Force Logistics Command channels, and funds to support missile RPIE are programmed through Strategic Air Command channels. Approval of funds for AGE without approval of funds for corresponding RPIE would create chaos. Even a minor change to Minuteman, accomplished across the whole fleet, requires major funding. About a year ago Hq USAF was apprised of this disparity in programming and funding and is now in the process of identifying detailed Civil Engineer responsibility in support of missiles in appropriate Air Force manuals and regulations.
Under current regulations, engineering responsibility for RP/RPIE in support of a weapon system passes to the using command 45 days after turnover of the last facility by the contractor. Engineering responsibility includes central engineering control to ensure uniformity of installations for standard operation and maintenance and to update operation and maintenance manuals. SAC civil engineering manuals are to RP/RPIE what technical orders are to AGE and AVE. Only recently did SAC receive authority to organize a separate engineering staff to provide these special services.
In the deployment of any modern weapon system, hardness, reliability, and dispersal are prime considerations. To visit every one of the sites of a dispersed Minuteman wing means traveling about 1400 miles by the shortest road. Dispersal compounds construction and also compounds operation and especially maintenance. SAC missile sites are 30 to 150 miles away from a support base, and this presents logistic problems in the transportation of men and materials out to a site and back. Operation and maintenance of either a Minuteman or Titan II wing require about 8,000,000 vehicle miles a year.
Since missiles and facilities were not prototyped, initial operation became, in fact, mass shakedowns. Usually, trouble did not develop at one site only. The Maintenance Data Collection System Reports and the Monthly Maintenance Summary have confirmed the consistency of American manufacture. Parts that were misapplied or of faulty design were readily identified. Under normal operation, idiosyncracies can show up. A good example is a certain relay used extensively in Minuteman wings. The unit complied with all requirements of the specifications. However, the heat generated in an energized unit is sufficient to slowly evaporate the last coat of insulating varnish, and these vapors settle on the contacts and entrap dust. The dust-laden contacts impair the flow of electricity when the contacts are closed and cause malfunction. For reliable operation, the contacts must be cleaned periodically, an operation not anticipated in initial planning. The units had been installed well over the guarantee period before the trouble developed.
Under normal operation, design oversights and peculiarities or shortcomings in the various systems are learned, and changes to standard operating procedures are made where indicated. For example, frost is usually considered to start at the surface of the ground and penetrate downward. When a continuous mass of outside air passes through a vertical concrete shaft, frost can start even at the bottom of a ten-foot shaft and penetrate in any direction during an extended period of extremely cold weather. Thus, a drain line buried below the normal frost line but three feet horizontally from the concrete shaft can and does freeze. — Diesel generators and associated electrical transfer gear did not attain design reliability without considerable adjustment and in some instances modification. Extended periods of cold weather affected the environmental control systems, which in turn affected the starting capability of the diesel engines. Accordingly, changes were made to the environmental control systems. — Under adverse weather, especially thunderstorms, certain conditions developed which precluded operation of the standby power systems as designed. Changes to the power generation systems and transfer gear were also necessary.
The design, construction, operation, and maintenance of intercontinental ballistic missile real property/real property installed equipment represent a very important milestone in the continuing effort to maintain our country as the world’s major deterrent force against aggression. The whole program was a rewarding challenge to the intellect of every participant, as much of the knowledge required for accomplishment was developed during that time period. This new knowledge was not limited to basic science and its application but included new highs in management, organization, and time phasing of construction. The missile program proved the merits of the Program Evaluation and Review Technique (PERT) and the Critical Path Method (CPM) of scheduling and monitoring production and construction.
Hq Strategic Air Command
Roman A. Metz (B.S.,
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