Economic and Strategic Considerations in Air Base Location
A Preliminary Review
This paper is not intended to locate and describe preferred air bases, but rather to locate and describe some of the elements of the base problem, with special reference to economic and strategic considerations. While the paper's primary purpose is to survey and orientation, certain of the differences which it indicates might warrant conclusions as to policy at an early date. These are: considerations of cost of installations as contrasted to total weapon system costs, (2) economy in aircraft weapon systems using ground refueling as against systems depending wholly or mainly on aerial refueling, (3) economies to be effected through such passive defense measures as dispersal of aircraft and preparation for repair of air bases, (4) large differences in systems costs entailed by location in such areas as the Arctic as distinct from Temperate Zones, and (5) the even greater differences in total systems costs when operating from adequate locations as compared to poorly situated bases.
Systems Costs Traceable to Base Decisions versus the Costs of Installation Elements
Military construction authorized by Congress for fiscal year 1952 includes some 3-1/2 billion dollars for air base construction, a billion and a half of which is overseas. These bases are planned to bring existing facilities to the level required by a 95 wing Air Force (80 combat wings). For the 140 combat wing Air Force being discussed in Congress as a projection for 1954, a very much larger volume of new construction is planned. These sums are considerable. However, in the total initial system costs as studied at RAND, base costs (in the sense of the cost of the fixed facilities, the real estate and structures required for the use of aircraft and personnel) generally make up about 15 percent of the total initial outlay for an aircraft system and about 10 percent of the original investment in a missile system. Maintenance of the fixed base elements entails a very much smaller proportion of the annual total systems costs, roughly three percent. Over the projected life of the weapon systems, the installations portion will be less than 10 percent.
However, neither the considerable sums involved in the cost of base installations nor their proportion to total initial systems cost, adequately measure the importance of base selections for the cost and effectiveness of aircraft systems. Base decisions affect the performance of a wide range of system elements other than the base installation itself. Deciding to put bases at points far removed from the target may mean increments in the number of air crews and in the number and size of the aircraft needed to perform a given task with massive effect on both initial and annual system costs. On the other hand, placing bases near enemy striking power may mean very large costs in defense of the base and large expected losses to enemy action. It is necessary to distinguish then, between system costs which are traceable to decisions on the location of the base and the cost of the installation elements themselves. Economizing on installation costs will not necessarily mean economy in the total system costs.
Base location both here and abroad for the expanding Air Force has naturally been affected for the past few years by the availability of existing facilities capable of reactivation and improvement. By and large it is cheaper as far as the cost of an installation of a given standard is concerned, to use an existing field rather than to start from scratch. (In this study we are exploiting this possibility of saving in our choice of base complexes.) In any case the criterion of maximum use of existing facilities has been an important selling point to an economy-minded Congress. However, if the existing facilities are badly located for sustaining the operation projected, they can be very expensive as compared to well-located new installations. Again, concentration of the buildings, hardstands, etc., on an airfield may effect some economies in the cost of construction and operation at the expense of larger costs in base defense and expected damage. The critical question concerns the total cost to accomplish the objective.
The possible difference between very large system costs affected by base decisions and the significant but smaller costs of various base elements provides leverage for base policy. Runways, for example, are cheap in comparison with the initial and annual cost of the aircraft using the runway and also by comparison with some relevant methods of active defense. Adding strategically placed runways may save air defense, bombers, and bomber crews.
Overseas bases are justified, if at all, only in some such terms. This has been recognized. General Vandenberg, for example, in testifying before the Armed Services and Foreign Relations Committees this May, made a rough estimate that it would take perhaps five or six times as large a strategic Air Force to operate solely from bases in the Western Hemisphere than the United States owns itself, as it would cost to operate from "adequate bases in the proper places." Even if the cost differences are considerably less than this, analysis of the adequacy and placement of base operations would be very fruitful.
Such analysis of course, should cover alternatives to overseas ground base operations, such as exclusive dependence on long range intercontinental bombing systems, either unrefueled or refueled in the air. A consideration of the location problem cannot preclude the possibility that the best place for all our air fields is in the Continental United States. The Zone of the Interior might emerge as optimum and will be our benchmark. Whatever solutions do emerge, it is apparent that the structure of bases and their location are an important area in which to find optimum or at least good solutions. Benefits may be gained, not only in the cost of installation elements, but, more important, in the total cost of aircraft systems.
Location and Locality Costs
Total aircraft systems costs are affected by the relative positions of our bases with respect to their source of supply in the Zone of the Interior, the boundaries of enemy territory, (or the points from which they might strike at our bases), the targets which are our objectives, and the defense area which must be penetrated to reach these targets. For convenience we will call the system costs which are a function of certain distances between these points—the base, the ZI, the target, enemy striking power, enemy defense—"location costs." They may be distinguished from the locality costs inherent in a specific site which are not functions of these critical distances but which are traceable to local phenomena such as climate. Under this head may be considered variations (a) in the cost of operations traceable to weather, (b) construction costs depending on climate, terrain, existence of a local construction industry and the availability of local construction materials, and the presence of existing base facilities, (c) supply costs affected by local terminal facilities for transportation and the possibility of offshore procurement from local sources, and finally (d) defense costs affected by terrain and existing defenses.
The magnitude of some of these location costs are presented in Section 7. The present section is intended to indicate in qualitative terms the importance of locality costs.
Locality costs do not vary steadily with the critical distances we have listed, and they are less amenable to presentation in a simple, functional form, but they are, nonetheless, substantial. Costs of basing aircraft in the Arctic and Sub Arctic illustrate this. (Though these are by no means the only important type of locality to be considered.) In brief, Arctic operation involves extra costs in (1) construction, (2) logistic supply and pipeline, (3) equipment and clothing required, particularly for heating purposes, (4) number and training of personnel, (5) increased maintenance needs of materiel, (6) low aircraft utilization, (7) high base vulnerability, and (8) low recuperability after damage.
Construction costs are much higher than either in the ZI or in any other base location. This is so both because the design requirements are greater and because resources are very limited and the conditions of their use critically difficult. Aside from the extreme cold and brief season in which construction is possible at all, there is, of course, no existing construction industry. Construction materials of all sorts and construction labor all have to be imported, fed, and housed, and paid extremely high rates to compensate for the comparatively short period of employment, and the difficulties of working conditions. For Alaska, the Army engineers' cost estimates are obtained by multiplying the Zone of Interior costs by a factor of 2.5. (Moroccan costs are obtained by multiplying ZI costs by 1.5.) These cost estimates are prepared for budget purposes. Actual costs may exceed these. The Hoover Commission Inquiry into Alaskan Housing, for example, found the costs considerably higher. The Air Base at Thule in Greenland, some 800 miles below the North Pole, in which a great amount of effort is at present being expended, is scheduled to cost some $250,000,000. This compares with some 50 or 60 million dollars for medium and heavy bomber installations in the U.S. The construction of Thule is a tremendous undertaking which involved flying some 11,000 people up to the building site this past summer.
Needless to say, logistics supply problems for such sites are enormous. This past year, fuel had to be flown in to Thule and normal resupply will be complicated by the long periods in which the port is closed by ice. In such localities a much larger stock of materials, parts, and supplies of all sorts has to be maintained than is indicated merely by the miles of pipeline to the United States, to take care of periods when there is no flow through the pipeline at all.
To make possible operating in such temperatures one needs Herman-Nelson heaters for preheating aircraft engines, Arctic survival and rescue kits, portable engine shelters and nose hangars, extra batteries for all equipment, extra vehicles, etc.
Lowered personnel efficiency makes large augmentations of personnel necessary (both in number and skill). Men have to be given special Arctic pilot training courses and are sent to service training schools. Information on augmentation in number is generally not very precise. One rule of thumb commonly used indicates that the efficiency of personnel is reduced two percent for each degree lowering in temperature below 0 degrees F. Additional personnel augmentation is required to handle increased maintenance loads. Preflight maintenance involves not only preheating cold soaked engines, batteries, electrical connections and instruments; it also involves finding and repairing leaks through cold hardened rubber seals and tires.
While each wing has more personnel, they can manage, under the conditions of operation usual in the Arctic, fewer sorties per aircraft. (One source estimates the sortie rate at half that in the Zone of the Interior.) Problems arise from sudden icing conditions peculiar to the Arctic, and from sudden weather changes which put a premium on navigational skill. The difficult terrain makes forced landing difficult. And even if the landing is successful, chances of survival are diminished. The isolation of these bases makes their defense an especially difficult matter — this despite the contrary impression one might gain from the frequently referred to virtue of being located in the Western Hemisphere. In winter all of the many Alaskan lakes are possible landing fields for airborne troop attack; and though Alaskan bases are not close to Russian industry, and even though they are in the Western Hemisphere, they are very close to the Russian border and Russian means of attack. The ability of units to recuperate after attack would appear to be low, especially in the winter. Typical problems would be: repairing cratered runways, loss of shelter for personnel and equipment, and length of time for resupply and reconstruction. Thule, for example, can be reached only by air for most of the year. An attack in the fall or winter that destroyed a substantial portion of the buildings would put this base out of action until the following summer.
The seasonal variations in hours of day and night at these bases and along the penetration route of bombers using these bases are very large in amplitude. This has considerable effect on the attrition rate, and therefore on the variations in system cost of an Arctic base complex, depending on the time of year in which the campaign is fought.
In spite of the fact that we do not now have precise measures of Arctic locality costs, it is worth spelling out these considerations at some length to indicate the way in which practically all of the elements of systems costs are affected by basing the system in such localities. In view of this fact and in view of the very considerable weight which is given to such operations in the Air Force program, it should repay the effort to try to gather more quantitative data on Arctic and other locality costs. In this first exploratory study we have instead concentrated our attention largely on the costs which vary with location with respect to the target, the ZI, and the boundaries of enemy striking power and defense.
Weapon System Analyses and Base Selection
It is clear that base determinations are closely dependent on the predicted characteristics of the weapon that will be using the base. Among aircraft, for example, turbojets appear to fare worse than turboprops with increasing distance from the target. The cost-increasing effects of combat radius appear to be more drastic at very low and very high altitudes and at very high speeds. For this reason base systems which reduce combat radius will appear to better advantage in the context of turbojet systems, and might increase in preferability with the increasing extremity in altitude and speed of the planes we choose. To take another example, the Intercontinental Bombing Systems Analysis suggests that bombing systems with limited supersonic capability will, in the years from 1956 to 1960, be more economical when penetration distance from the border of enemy defense to target is within the limits of their supersonic radius. Bases chosen as to reduce penetration distance may appear in a particularly favorable light if we assume that the Air Force has a considerable proportion of such bombers. For such reasons base selection depends on weapons choice. It is also clear that for converse reasons weapons choice is not independent of base selection, and that analysis of the base problem can increase the soundness of our aircraft systems analyses.
This last point is rather widely recognized at RAND. MACS, to cite the most important example, is considering the sensitivity of its results to base changes. In the first systems analyses, base and target location appear essentially to have been indications of the accessibility of a considerable list of targets to aircraft with the design range examined. The actual physical distribution of base and target sites did not enter into the calculations. In the Strategic Bombing Systems Analysis and in the Multiple Strike study the comparisons were concentrated at one range: 3,600 miles. All, or at any rate most, of the targets were shown to be accessible from one or another of three selected primary bases. Of course in the target areas drawn, a considerable number of the targets were closer than the outer rim of the target areas. However, no account of this fact was taken by adaptation of any of the system elements to the varied smaller range requirements. In effect, it was assumed that all of the targets were lined up along an arc swept out by the design range studied.
Some minor qualifications need to be made to this summary. In the offensive bombing systems analysis a post-strike staging base was assumed or mentioned as making some more distant targets accessible. However, while this was introduced in order to give the various systems the possibility of a shot at further targets, it is not clear that the costs of these bases were included in the actual calculations.
In the multiple strike study there are some interesting comments on a one-way bomber system. While the operational feasibility of such a one-way system was not dealt with, the example showed that under the conditions assumed, the advantage of turboprops over turbojets disappeared and, in fact, that there was a slight cross-over. In effect, this one-way bomber system is a kind of stand-in for a two-way system operating at half the range studied; but the base costs for an overseas base would have to be added to complete the system cost for a two-way system.
In current systems analyses base assumptions are both more explicit and more varied. However, such difficult questions as the costs of base vulnerability or ground attrition have been largely postponed or fixed arbitrarily by assumption.
In sum, the juxtaposition of base problems and RAND systems analyses should benefit both.
Political Conditions of the Base Problem
The problem of selecting points in space so as to minimize system costs depending on various critical distances—distance to target, distance to sources of base supply, distances of penetration over enemy defenses, distances from enemy striking power to the base—is, of course, by no means merely a problem in geometry. Political considerations dominate. They affect: (1) Whether a given country will make available to the United States, land for air base development at all; (2) Where it will make a base available: the exact location within the country with reference to transportation and population centers; therefore, the logistics cost, operational suitability and possibilities of defense; (3) How long it will take to make it available; the lead time in obtaining a base; (4) The method of financing and carrying through base construction, and even the types of structure used; (5) The level of operating or manning which the country will permit; (6) The possibility of interference with base operations once a base is developed, by activities of sabotage or the like; (7) The likelihood of sudden withdrawal of base rights by the government of the country granting them; (8) The mission of the base; (9) Our contribution to the land and sea defense of the country granting base rights.
Any realistic consideration of the base problem has to conjure with these political facts. They restrict the solutions possible and they also put a premium on having a clear-cut program for base expansion with alternates in case of failure anywhere along the line from negotiations to final use.
Consider the first five points mentioned which are closely connected. Take the question of base availability. The problems here concern both the countries which are securely allied with us, and those whose alliance is quite uncertain. It doesn't solve the problem therefore merely to sort countries into probable allies on the one hand,—and probable neutrals, probable enemies and doubtful cases on the other,—and to stick to probable allies. Even our major allies, such as France and the United Kingdom have great difficulty in granting suitable bases. The problems connected with the precariously aligned countries are even more evident. Though it is possible to exaggerate the uncertainty of international alignments (in sorting countries, the relatively certain cases do outnumber the doubtful ones), there is no question about the importance of the precarious areas. The mobility and uncertainty of political alignments in such important base areas as Africa, the Near East, and the Middle East, are only too evident in the current headlines. Here the problem is complicated by complexities in the relationships between our major allies and the colonial and semi-colonial countries, which are in various stages of the process of detaching themselves from colonial dependency.
In the metropolitan countries the land problem is especially difficult. The well-drained, fairly level land, best adapted to air base construction, is also in general, the best adapted to any other variety of construction: housing, schools, commercial and industrial building, roads, power stations, reservoirs, and military depots. And it is also in general, the best land for food production. In a country like the United Kingdom, the competition among these uses is most intense. To indicate how tight an island the United Kingdom is, some figures from a recent progress report of the Minister of Local Government and Planning may be cited. England and Wales have some 37 million acres of land, 24 million of which are devoted to farming; and a population of 44 million. If Scotland is added in, the totals are 68 million acres of land, of which 28 million are improved farm land; and a population of 49 million, as of last year. This means just about half an acre of food-producing land per person. One important part of the United Kingdom's program for solving its serious dollar problem is the expansion of domestic food production. When this situation is coupled with the intense housing shortage, it is apparent that an increase in the number of air bases is limited and that the island is tight enough to make local dispersal on any given base very likely to be a real problem. This is confirmed by the account of operations officers who have been concerned with air base defense and location in England.
It is not only a question of making a large claim for restricted resources in land. The actual base construction is a vast project which will make a claim on other resources of the country. And so subsequently does the continuous presence of American soldiers. Depending on how the construction is carried out, the extent to which local industry is used in production, or the extent to which American labor is imported and appears in the economy largely as spending units, the base construction may be an important form of economic aid or it may be a very disturbing, inflationary element. The dislocations in the wage structure, especially in dependent overseas territories, form the subject for a considerable number of State Department cables.
The continuous presence of American troops has similar possibilities of inflationary disturbance. It involves a host of problems stemming from invidious comparisons of the standard of living of our troops with that of the local population, plus the usual problems of illegitimacy and racial and cultural conflict. The level of manning at the bases is a principal point of negotiation. It is difficult to get military rights for an installation in which we intend putting a large complement of men. And most of the treaties negotiated have placed ceilings on the number of troops we are allowed to bring in.
The negotiation of these treaties is a long-drawn-out trying matter. They appear to be averaging some two or three years, and far exceed the base construction time. Of the various elements present in the usual base mixture in the past: landing, take-off facilities, refueling facilities, maintenance, storage of aircraft, and housing, the last is the most disturbing so far as native populations are concerned. Storage of personnel is considerably more volatile than storage of petroleum. In the opinion of the men concerned with these negotiations, their time length would be very much reduced if we restricted our objectives to staging bases involving a minimum of personnel.
For similar reasons, large bases involving a great many personnel are more easily tolerated by our allies if these bases are placed at a considerable distance from population centers. We could, to take the example of the Moroccan Bases, have had our choice of real estate along great stretches of the French Sahara with very little time wasted in bargaining. However, this would have meant a morale problem as far as Air Force personnel is concerned; and, since population centers and transportation centers are generally related, it would have meant great increases in supply costs.
The last four points mentioned at the beginning of this section are closely related. The availability of bases and the conditions of their use are sensitive not only to the formal commitments of the government of the country granting rights, but, like this government itself, to the views of local partisan political movements. For such reasons, the commitments are frequently tentative. A good many of the treaty rights negotiated are on a year-to-year basis. In a great many of the countries with which we are dealing, communism is a considerable force. But even more closely affecting base use, the manner of operation, and the mission to which the base may be devoted, is the wide range of non-communist views which differ in the values which they attach to the presence of a U.S. air base in their country. In general, it seems that a base which is looked on as a means of defense of the surrounding area is welcome. A base which is a means for delivering the A-bomb against the Soviet Union and which, in turn, may be the object of Soviet A-bomb attack is not regarded as an unmixed blessing. Questions both of base availability and mission restriction will be answered differently, clearly, depending on the degree of warmth of the cold war. The willingness of the governments of our allies will vary as will the latitude permitted these governments by dissident groups. And in the case of hostilities, it is not excluded that we may take control by a show of force. We did this in the case of Iceland in the last war. The significance of restriction on the mission of a base will depend on whether we are at war or not and on the circumstances of the outbreak, that is, the relation of the war to the interest of our allies.
It is only natural that the country granting treaty rights to the U.S. should have a very strong interest in the kind of mission our planes based there will fly. Our strategic striking force is an obvious target for the Russians; in the opinion of our own Air Staff, the highest priority target for the Russians. There is some justification, then for feeling that a SAC base increases both the general security of the allied forces and the specific hazards of the area in which it is based. A fighter base with an overtly defensive mission is something else again.
The question of defense of the country granting military rights is, of course, a key question in base negotiations. Our ally will naturally be reluctant to grant bases if he feels certain to be overrun and to have to face Russian retaliation for the act of making bases available for U.S. planes. Therefore, our participation in defense on the ground and our protection of the sea lanes to his country are of great moment in his decision. On the other hand, it would be in error to attribute all of the cost of such matters as keeping the air and sea lanes of communication open, to the operation of our base. There are other reasons as well for doing these things. We shall return to this point.
First, there are several points to be made on the basis of these considerations. The factors described place constraints on solutions to the base problem. 1) Some areas, no matter how well adapted to base use, may be eliminated as not likely to yield base rights under any likely circumstance. Sweden, for example. 2) Other areas which might yield base rights may become ill adapted to base use by the political realignment of their neighbors. If Greece or Yugoslavia were to be absorbed into the Russian sphere of influence in advance of the outbreak of war, the usefulness of such base areas as Libya, which are well situated given the present alignment, would be decidedly decreased. 3) The problem for a base right program is a quite specific one; in what politically autonomous areas are there base locations that could supplement our existing base structure? This involves a choice of several among a comparatively limited number of alternatives. 4) These political considerations restrict the number of solutions possible to the base problem. They also operate to reinforce certain technical and economic factors determining the distribution of base functions. 4a) For example, the uncertainties of political alignments suggest that it is advisable to have a good many bases and to have them in a number of politically distinct areas. This reinforces the indications favoring multiplicity and dispersal of bases which are the result of analyses of the vulnerability of bases to enemy attack. 4b) For another example, the restrictions placed on obtaining missions for strategic air operations suggest the importance of standardizing some of the facilities required for fighter bases, say, at a level which would permit their strategic use. This device has technical advantages for passive defense and for providing flexibility. It also might permit conversion to SAC use in the event of a change of heart in the country granting military rights. 4c) And finally, the difficulties involved in extensive manning point in the same direction as certain vulnerability considerations. The storage of aircraft is a most vulnerable base function. There are considerable advantages, of which SAC, for example, is aware, in basing SAC personnel and aircraft permanently in the ZI in time of peace, and keeping the overseas bases partially manned on a rotating basis. (In a variety of circumstances it appears also that it might be advantageous, even in time of war, to base aircraft and men further back, and to have landing, take-off and refueling forward.) This sort of base development obviates some of the political difficulties involved in extensive manning.
The considerations outlined affect the problem of obtaining bases overseas. The sizable list of difficulties might, of course, suggest the virtues of basing our air power entirely in the United States. They do, in fact, suggest this to a good many people; though this is not the official view of the Air Staff itself. The air power one has in mind in this connection, of course, is strategic air power. For several years there has been a considerable sentiment emphasizing the long range capability of SAC, and putting a premium on its power to strike at the Soviet Union from within our own borders rather than from foreign territory. While this view is not a simple logical consequence of the Sunday punch theory examined by Brody and while there are some people who hold one view without the other, they are emotional twins. A Sunday punch is a round-house, not a jab; you start it from away back. Both views relate to the belief that the United States alone, if not the USAF or even SAC alone, can reduce the Soviet Union to submission, that is, unconditional surrender, and that this is the best, cheapest, quickest, and least painful way to do the job.
There is no denying that there is a good deal that is attractive in these views; particularly, perhaps, the intercontinental character of the blow. Throwing a punch while standing way back where you are hard to hit has obvious advantages — provided, of course, you have the reach or can develop it without stretching your resources. Aside from the advantage of being independent of the vagaries of our foreign allies, the diminution in vulnerability is very obvious. On the other hand, at the moment we do not have the reach and it might be questioned that a short intercontinental strategic campaign alone will, in fact, (1) economically reduce the Soviet Union to swift submission (though there is no doubt about SAC's critical importance, as part of a many-sided effort, to the ultimate outcome of the war); (2) stop the Soviet Union from taking Europe and other critical areas we want to deny them; (3) and assuming (1) and (2) accomplished, obtain the best conditions for a stable peace. (This last point has been made very strongly by members of the RAND Social Science Division.)
If our strategic air campaign alone were capable of achieving our objectives, then from the standpoint of accomplishing this purpose, all the costs of our overseas alliances and our Army and Navy might be regarded as part of the price of obtaining overseas bases for SAC, and this would be weighed in the balance in comparison with systems for destroying Soviet targets from the United States. This, stated baldly, is one extreme Air Force view. The official Air Staff view, however, takes the strategic air offensive as the first, but not the only basic wartime requirement. The defense of the North Atlantic Treaty area and of the Far East, and the security of sea and air lines of communication are high priority tasks. This is consistent with basic U.S. foreign policy commitments, which in turn are founded on the belief that it is important to prevent Russia from spreading its industrial and agricultural base by taking over Europe.
In attacking the base problem it seems best to be clear about what we are assuming in this regard. We are assuming the defense of the NATO area and the system of alliances on which this defense is based. We do this because it hardly seems appropriate to conduct a re-examination of the entire range of American foreign policy as one side study for the base problem. Because we do this, something less than the entire cost of our Army and Navy and of various programs of foreign aid will be chargeable to the obtaining of bases overseas. No matter where we base SAC, we will be keeping sea lanes open and we will be contributing to the defense of our allies, and we will have fighter and air transport bases in various parts of the world. The location of our strategic and tactical powers will be considered in this light.
Ambrose Bierce in his Devil's Dictionary, defining some such term as "projectile," remarked that the excellence of this invention, a great improvement over physical conflict, had been qualified up to that time by the apparently ineradicable need for personal attendance at the point of propulsion. Bierce, of course, lived in a period before the development of control through program tapes and other such wonders. However, even in the case of the missile, presence in the general vicinity of the launching not only of personnel but of equipment and perhaps of a large supply of parts for assembly, is likely to be needed for some time to come, so that considerations of vulnerability, which increases with proximity, must be balanced against such advantages as close aim. In short, the advantages of proximity appear, unfortunately, to be symmetrical.
What are the advantages and disadvantages of proximity? It would appear on first examination that, in general, as we move our base operations along a given line away from the target, we (1) diminish the probability of enemy attack against our bases by lengthening his own combat radius; and so we reduce the cost of defending the base or the expected damage for a given level of defense. (2) We shorten our supply lines and thereby lower both the normal peacetime transportation, travel, and stock costs as well as the cost of defending these supply lines and the expected losses to such enemy attackers as submarines. (3) By and large we increase, though not steadily, the political security of our base operations: in the limiting case back in the Zone of the Interior we not only come in under the umbrella of continental defense, but we apparently depend on no political alliance other than the satisfactorily secure one among the 48 states.
On the other hand—again in general—as we move our base operations towards the comparative shelter of the Zone of the Interior, our aircraft grow in size and number and our aircraft personnel increase in proportion to number. Unrefueled aircraft grow in size, moreover, at an increasingly rapid rate with increasing combat radius. Growth in airframe weight relates directly to increasing costs of procurement; the growth in both dry and gross weights, to other system costs such as runway, fuel, and fuel storage, stock and maintenance costs. The increase in the geometric volume of an individual aircraft or in its plan-projected area means an increase in its vulnerability and in probable loss to enemy area and local defense; therefore it means more aircraft and aircrews in replacement to keep a given number of aircraft in operation; therefore higher costs. The increase in mission distance means more petroleum consumed, less pay load carried, greater flight fatigue, and, what is most important, fewer sorties flown per aircraft; therefore more aircraft and more aircrews to fly a given number of sorties. If the normal base operation of refueling is performed in the air, this means more aircrews and aircraft in the form of tankers, with corresponding increments in cost. Missiles, like unrefueled aircraft, increase in size, costliness and vulnerability with increasing range; moreover, (at any rate in the case of those missiles anticipated in the next few years) their inaccuracy is an increasing function of range; therefore increased range means higher cost to destroy targets.
The symmetry and simplicity of this picture, however, are incomplete. First of all it is asymmetrical, in that our capabilities differ from those of the Soviet Union, so that the optimum base location for ourselves is not necessarily the best position from the Soviet Union's standpoint. Second, the realistic physical configuration of the problem involves Russian targets placed at various points within Soviet and satellite boundaries. These boundaries within which area defenses and air bases are disposed in specific ways have a peculiar enough shape to make fruitful a systematic comparison of other distance relationships than the one between the base and the target. Third, we can find bases with equal combat radii to target, some of which have the advantage from our point of view, of being further from enemy striking power, or which involve smaller penetration distances over enemy defense. In fact, we discriminate at the start the distances from the ZI to base, from base to target, from the enemy defense penetration point to target, and from our base to the enemy striking power. Because our target, enemy striking power, and the boundaries of enemy defense are all distinct, we have, within limits, the possibility of varying these critical distances separately. Fourth, our bases themselves are composites of functions which it is pertinent to analyze separately in relation to these critical distances. The various base functions — landing and take-off, refueling, aircraft storage, housing and maintenance — are partially separable. Since these functions have differing vulnerabilities, locating them at differing distances from enemy striking power might be indicated. And since their location with reference to the target has effects differing from one to the other, separation may be indicated by this too. The location question properly posed refers to the positioning of base functions rather than of whole bases with the conventional mixture of functions. This is true both for considerations of location in a macroscopic sense — the world distribution of base functions — and microscopically — for the local dispersal of functions on a specific base.
Selected Bases and Their Critical Distances
To illustrate base variations in combat radius, logistic support distance, and distance from enemy striking power, we have selected 13 base locations (four of which form the base system for MACS) and taking a 100-point industrial target system, made rough measures; measurements of penetration are also being made. Logistic support distance is approximated here by the distance from the base to the port of New York or San Francisco, whichever is nearer; distance from enemy striking power by mileage to the closest point on Soviet or satellite borders; penetration distance, by miles, over enemy territory corresponding to the various combat radii. The results of these measurements are presented in Table 6-I. Distances to the ZI range from zero to about 11,000 miles; distances to the Soviet border from under 500 to over 3,000 miles. Combat radii vary from about 1,000 nautical miles for Cairo against target area 6 to over 5,000 nautical miles from either Limestone or Spokane against target area 7. If we assign targets to the nearest base, the average radius to all the targets from the resulting "closest" base complex is about 1,400 nautical miles.
This may be contrasted with the combat radius to all the targets from a base complex limited to the ZI. If we take the ZI subset of these bases, namely, Limestone or Spokane, and assign each of the 100 targets to the nearer of the two, the average distance is about 4,000 nautical miles.
These distances from base to target are measured without dog-legging. In fact, it might be necessary or advantageous to dog-leg in order (a) to reduce penetration, (b) to refuel in the air at some identifiable point, or (c) to refuel on the ground at an advance base. Any of these would make it necessary to modify our base-to-target measurements. The third kind of modification, which takes into account increases in combat radius required by refueling at specific advance bases, is illustrated in Section 12 in connection with our ground and air refueling systems comparison. The second modification has so far not been made. The first, which increases combat radius to reduce penetration depends on a determination of the exchange rate between the extra costs of going further from base to target as against the losses to enemy defense which might be saved by the detour. While we have quantitative measures of the cost of increasing combat radius, the determination of this rate of exchange awaits better understanding on our part of penetration costs.
Section 13 compares the 13 bases with respect to costs per sortie to each of the targets for the U.S. Strategic Air Force as projected in 1955-56. In these comparisons, location costs such as the systems costs which vary with combat radii, the logistic costs which vary with ZI distance, and the base defense costs which vary with Soviet border distances, are considered.
Before returning to this illustration, some more general considerations are presented in the next sections on the effect of location on refueled and unrefueled bombing systems cost.
Illustrations of Bombing System Costs as a Function of Base Location
A. Up to this point our investigation of the effect of the critical distances on systems costs, being preliminary, has been deliberately crude. We have been interested in gauging roughly the magnitude of these effects and, to this end, some exploratory cost analyses have been made using both the generalized or variable range aircraft studied in R-171 and the fixed range aircraft which the Air Force schedules for operation in 1955–1956. For later periods we propose to investigate the location costs of the low altitude and supersonic bombing systems whose development is now anticipated and also the location costs of missile systems.
B. Unrefueled generalized bombers and combat radius. The curves in Charts 7-I and 7-III represent continuous families of aircraft, each point on a curve corresponds to a different plane operating at the design range indicated.
B-1. The cost per sortie as a function of combat radius. The cost per sortie measure has been chosen as giving some notion, in advance of performing an actual campaign analysis, of what it will cost to mount a given rate of attack. It is calculated by dividing the four-year budget cost per aircraft by the sortie rate, in this case the sorties per month. The use of the time interval of a month in the sortie rate does not affect the relative standings of the various systems: The time period is factored out in the comparison and these comparisons are independent of the length of the campaign assumed. The effect on this measure of taking into account aircraft attrition is discussed in Section 7-C.
The cost per sortie for the turboprop flying at 40,000 feet altitude, 400 knot speed, and a bomb load of 8,000 pounds (Chart 7-1) shows a drastic decline from 11 to 1, as the base is shifted from 5,000 mile combat radius to target to 1,000 mile. The two turbojet cases (40,000 foot altitude, 400 knots, 8,000 lb. bomb, and 47,500 foot altitude, 400 knots, 10,000 lb. bomb), as would be expected show an even more drastic rate of decline.
We have not as yet explored the location costs of aircraft systems of the vintage studied in the intercontinental bombing systems analyzed. It appears, however, that they are, if anything, more sensitive to combat radius than the more conventional aircraft depicted in our curves of Chart 7-I. The charts that follow decompose these curves into several significant components.
B-2. Cost per aircraft as a function of combat radius. Chart 7-II presents the total systems cost per aircraft for the three selected bombers. The first case is that of the turboprop with a capability of 400 knots, an altitude of 40,000 feet, and a bomb load of 8,000 pounds. The weight empty of this type of plane diminishes from 108,000 to 35,500 pounds as the combat radius changes from 5,000 to 1,000 nautical miles. The decrease from 4,000 to 1,000 is almost linear. The systems cost as usually calculated at RAND, that is the initial plus four annual years of peacetime cost per aircraft, declines (at a somewhat smaller rate). These costs exclude both aircraft attrition (in the air), and base vulnerability.
B-3. Aircraft attrition as a function of plan-projected area and combat radius. As the plane shrinks in size with diminishing range requirements, its vulnerability to enemy area and local defense also diminishes. Chart 7-III shows the reduction in cost per aircraft that accompanies this diminishing vulnerability. The decline in this curve, which is the work of R. Schamberg, is rather moderate. It is possible that some of the attrition studies being made in connection with MACS will show a larger decrease with plan-projected area and therefore with combat radius. In any case we are, at present, in no position to evaluate these attrition models. Hence this added effect of increasing combat radius has not been included in our estimates of cost per sortie and cost per aircraft charted in 7-I and 7-II.
B-4. Sorties per month as a function of combat radius. The curve of sorties per month, or its reciprocal presented in Chart 7-IV, are a logical consequence of the assumptions we have made, following WPF-50(A), that individual aircraft have a fixed utilization rate. (We have assumed 100 hours per month.) The assumption of a constant utilization rate is, according to N. C. Peterson of the Aircraft Division, plausible in time of war if not in time of peace. None the less, aside from the question of extensive battle damage, there is some question about the tail of the curve indicating 20 sorties per month. It is possible that a fixed minimum amount of maintenance is necessary which would preclude 100-hour utilization in the frequent sortie cases. This is one of the questions we feel needs investigation. However, the differences shown in our curves appear gross enough to survive any corrections that might be needed. As to the effect of battle damage, it is clear that this is a function of number of sorties rather than flying time. Since the cost curves in 7-I are on a per-sortie basis, the effect of damage will be to shift this curve upward.
B-5. The very considerable drop in total cost per sortie with decreasing combat radius suggests the importance of considering a shorter range bomber, (perhaps one with a thousand to 1,200 mile combat radius), than SAC presently programs. In Case #1, in fact, the gain in going from 2,000 to 1,000 nautical miles is approximately the same as the gain in going from 3,000 to 2,000. In Case #2, R-171 yields no point for the 1,000 mile radius. Case #3 is considerably flatter in the 1,000-2,000 mile radius than in the 2,000 to 3,000 mile radius. But, on the other hand, in all ranges, it is steeper than the comparable gain in the turboprop case, and it is considerable. That a shorter range bomber might be worth investigating is suggested also by two other considerations: (1) A considerable part of the target system is accessible at this range from bases assumed in various RAND bombing system studies. A little less than 40% of MACS targets are reachable from MACS' four overseas bases at less than 1,200 mile radius. The question here is how much the gains through using a more efficient plane would be offset by the extra costs of adding another model to the Air Force mix. (2) The value for Phase II operations should be a higher percentage of the system cost per aircraft than is the case with a heavier, more expensive plane. This is suggested by the fact that TAC buys this sort of plane.
C. Refueled generalized bombers and combat radius. There are a great many questions to be answered about refueling both in the air and on the ground before their advantages can be dealt with confidently. For aerial refueling, probabilities of rendezvous and other relevant matters are not known and the operational data permitting informed guesses are difficult to come by. For ground refueling at minimal in-transit or post-strike bases, we treat some of the important questions as to vulnerability (See Sections 10 and 12). In the case of aerial refueling we have merely made the usual assumptions. Some observations, however, are possible on the basis of the preceding discussion as to the segment of systems costs on which refueling operates.
The separate curves showing the variation in sortie rate with distance and the cost per aircraft with distance display clearly the dominance of the sortie rate influence in determining the drop in cost per sortie as a function of radius. This is significant because it suggests some of the limitations within which refueling both on the ground and in the air must work as a method of range extension. For a given range, refueling permits the use of a smaller, less expensive bomber and a less vulnerable one than an unrefueled bomber. In this way, it attacks the part of the cost per sortie formed by the cost per aircraft (Charts 7-II and 7-III), and against these gains must be offset the cost of tanker aircraft or refueling bases. It does not, of course, increase the sortie rate. Other limitations to the advantages gained by aerial refueling appear with increase in the number of refuelings required. The method yields diminishing increments in radius with increasing numbers of refuelings as the extra tankers must themselves fly further out and back.
Given a base and a fixed range, the advantages of refueling then, turn essentially on the magnitude of savings through reduction in plane size and related phenomena on the one hand and, on the other, the magnitude of either fueling base costs, including defense costs; or tanker plane system costs. For a fixed aircraft the advantage of refueling and operating from a remote primary base depends on the tanker system or refueling base costs as against the savings in cost through diminished requirements for defense. Some preliminary hypotheses on the fixed aircraft case are presented later.
We may compare not only the advantages of remote primary basing as against refueling, but also alternative methods of refueling—in the air or on the ground. At the present stage of our knowledge, this latter comparison is somewhat easier to make. Results of the first try at this are presented in Section 12.
Some qualifications are in order about the predominance of the sortie rate in cost per sortie and its influence on the role of total system range and refueling.
First, the importance of the sortie rate lessons with increases in the attrition rate. In the limiting case where there is 100% attrition, the influence vanishes. The guided missile illustrates this limiting case. Here, of course, there is no refueling but the importance of range reduction figures largely in the effects on missile size (which affects whether the missile attrition takes place before or when it reaches the target, whether it is intercepted) and missile reliability and accuracy. Similarly, if we assume the Sunday punch theory in its purity as a single mass strike, the sortie rate effects, of course, disappear. (This is another illustration of the connection between the Sunday punch theory and theories placing exclusive dependence on intercontinental bombing (see Section 4).
Second, in campaign calculations for self-refueled systems, the possibility of tanker bomber interchangeability permits a high rate of utilization of tankers as bombers suffer attrition, and this will affect system costs. This last point is important also when we consider aerial refueling from the standpoint of a supplementary or insurance device rather than as a substitute for an overseas base program. In this case the possibility of converting the other way around, from bomber to tanker, is important in the event of the loss of overseas bases.
D. Travel, transportation, and pipeline costs as a function of ZI to base distance. Chart 7-V shows the variation in days of supply as a base is located at increasing distance from the zone of the interior. The influence on the total stock level is also shown. The effect on stock level costs is the primary effect of ZI to base distance. The other effects concern travel and transportation costs.
In spite of the fact that ZI to base distances vary up to 11,000 miles in the 13 selected bases treated in Section 6, their influence on our totals appears to be moderate. The calculations of total B-47 systems costs for these various bases, the overall results of which are presented in Section 13 indicate this. Karachi, one of the bases farthest removed from the ZI, has roughly the same order of magnitude of combat radii to the 100 industrial targets; however, it is some 10,000 miles further away from the Zone of the Interior. The effect of this increased distance appears to be responsible for adding something less than $30,000,000 (twenty million for stock level, three million for travel and six million for transportation) out of a total B-47 systems cost for Karachi of some billion and a quarter. The influence is slighter on totals combining initial and annual costs.
This result is of considerable interest. It indicates the limits of significance, so far as overseas air bases are concerned, of innovations in logistics techniques for the regular peacetime resupply of airbases. At the expense of greater line haul costs per mile, air transport would reduce the time of resupply and so the pipe line levels required. However, even if air ton mile costs were at the level of surface transport so that there were no offset, the total cost of overseas stock in the system is too small to make even its total elimination of major consequence to our costs.
Some qualifications are to be observed. First, these comments concern peacetime resupply, not supply in time of war. The vulnerability of lines of supply in time of war involves other costs which we have not tried to measure. Moreover the vulnerabilities of surface and air transport will differ. (In a 30 to 90-day campaign of the sort usually assumed, on the other hand, this qualification would not be serious. We have assumed in our cost calculations a large pre-positioning of stocks.) Second, our comments concern the regular resupply function. Air transport can affect base location by reducing the time necessary to bring an overseas base from a standby condition to one of full operation. In this way it figures importantly in the SAC mobility plan, or in any plan which for reasons of vulnerability, political infeasibility, or peace time costs, employs primary bases remote from the target in peace and primary bases close to the target in time of war. These comments do not consider economies in locality costs that might be possible because of the lack of conventional terminal transportation facilities, and they do not consider emergency or other specific categories of supply. Finally, this says nothing of the possible importance of innovations in logistic techniques which would affect various air base systems indifferently. It is restricted only to the importance of such techniques for location costs.
E. Refueled fixed-range aircraft vs. combat radius. If we take a specific aircraft such as the B-47 or B-52 and consider the costs of sortieing this aircraft for a given distance, using aerial refueling to extend its range, these costs follow curves of the sort shown in Chart 7-VI. A major difference between these curves and the curves shown in Chart 7-I, is the appearance of jump discontinuities at distances requiring extra refueling. These discontinuities are a consequence of the fact that the plane functions most efficiently at its design range. The generalized bombing system curves are fitted to such points.
Two other observations may be made: (1) The jumps in cost are larger for later refuelings. The first two self-refuelings increase the range by about one-third for each refueling, the next two by less than 15% each. (2) These range extensions and their costs assume that bombers are refueled at an optimum point in the mission. This may not be possible. In fact there is an absolute limit to range extension by refueling for any given pair of tanker-bomber types, and the limit may occur earlier when, for example, the refueling points yielding maximum range extension are over enemy territory.
F. Penetration. It appears from the MACS' investigations on this subject that penetration effects are of major importance. Under rather restrictive assumptions involving huge mass strikes, MACS' attrition models show an approximately linear increase in attrition of aircraft with increasing penetration. We hope to learn something about penetration from the MACS studies, but so far we have not had the time to become familiar enough with them to see how they apply to our work.
Base Vulnerability Costs
Because the level of enemy attack capability decreases with distance from his boundaries, the problem of defending our bases so as to sustain any given level of operation changes as the base is located at increasing distances from his boundaries. The appropriate mixture of defense measures changes and the cost level declines. To fix these relationships quantitatively, we have posed the problem in the following way: Assume a given level of operations to be required for a fixed time period. To start with, take the SAC mobility plan and a Strategic Air Force composite of planes projected for 1955-1956. At any given distance from Russian striking power, what is the cheapest mixture of active defense, passive defense and preparation for repair, which will assure that the required level of operations be sustained? How does this mixture and its cost vary as we pull our bases back from enemy territory?
This requires, first of all, examining the facilities requirements for each of the base functions as these requirements are presently viewed in the Air Force and analyzing the costs of these installation elements and the expense of their multiplication, to determine what is at risk in bases as the Air Force at present programs them. Second, it is in order to review the rationality of these requirements from the standpoint of their performance meaning for the projected operation. Third, it is necessary to determine the probability of damage to these functions, given enemy fire. Fourth, it is relevant to examine the operational meaning of the damage sustained in terms of (a) the interruption of a function and the possibility of substitute or makeshift operations, and (b) the feasibility, cost and time for repair. Fifth, it is important to determine the cost and effectiveness of alterations in base design in the form of passive defense to minimize vulnerability. Such design might call for (a) structural changes, (b) changes in the amount of local dispersal of facilities, (c) multiplication, and (d) camouflage. (We might dig our fuel tanks in deep and cover them with concrete or divide them into a half dozen, separate, smaller tank farms rather than one large one, or simply have more of them or attempt to hide them.) Sixth, we have to analyze the various alternatives for active defense and their costs. In the next two sections we discuss some of these questions.
Expected Level of Attack Capabilities as a Function of Distance
The level of enemy attack on a base is one important and obvious determinant of probable damage. This level diminishes with increasing remoteness from his own strike bases. The diminution will be discontinuous at the points fixed by the range limits of the aircraft in his air force composite. Within fighter range he can concentrate a tremendous number of planes developed for this as well as for a variety of alternative uses. In addition to the bombers, fighters can drop napalm or frag-bombs and can attack the field by strafing. Beyond unrefueled fighter radius, fighter attack is still possible through such devices as refueling. But for a fixed amount of his resources the level of his attack will be available unrefueled in the distances between fighter range and light bomber range. At the medium bomber limit there will be another jump discontinuity, and so on.
The level of attack capability depends on the carriers and the amount of explosive material available. The allocation of carriers and explosive material to attack on any class of target depends not only on the relative importance of the various demands on resources, but also on the vulnerability of the targets we furnish. In our computations we have assumed that SAC bases would receive the attentions of a fixed force which is independent of target vulnerability. In general, for the period considered, the constraint on HE bombing will be carriers, while A-bomb attacks will be constrained by the amount of fissile material which he has available. Air base defenses should be designed to attrite the item in short supply. We have assumed that the SU can employ the following resources in continuous attack against our bomber bases: 150 A-bombs, 800 medium bombers, 1,200 light bombers, and 2,600 fighters and attack aircraft. We have also examined the effect of all-out attacks where the entire SU air force is directed at our bomber bases. The expected range and load capabilities of SU aircraft available in large numbers in 1955-1956 is as follows:
The expected number of aircraft in each category decreases markedly with increases in combat radius. If range extension devices, such as aerial refueling, are employed, targets beyond the basic combat radius will be subject to attack, but this is possible only at reduced sortie rates, and increased costs.
In measuring SU aircraft range capabilities from the border, we have perhaps been overly pessimistic. While it is entirely possible that airfields at or very close to the border would be used, such airfields would have the disadvantage of short radar warning times, and would be open to attack by a variety of types of aircraft. The symmetry is not complete, since Soviet defenses on the Soviet side of its border will doubtless be stronger than ours on the Allied side. On the other hand, we have postponed measuring the effect of possible advancement of Soviet bases before and after D Day.
On the basis of the fragmentary information available on the expected composition of the Soviet Air Force in 1955–1956, we have drawn rough curves approximating his sortie and his HE delivery capabilities as functions of distance from his bases to ours. These curves are presented in Charts 8-I and 8-II. The marked discontinuities occur at the range limits of the aircraft types which he has in large number. While by far the more important features of these curves are their drastic overall decline, the discontinuities have a local interest about which some comments are in order.
The discontinuities in enemy capability suggest one local criterion for base choice. If bases are going to be put in the general neighborhood of one of these points of discontinuity which mark the range limits of any of the enemy's aircraft types which he has in large volume, then it appears best to put the bases at the nearest safe distance beyond these points. This, barring matching discontinuities in the range capabilities of our own aircraft. Moving our base forward could mean a sharp increase in the level of enemy attack likely to outweigh any advantages accruing to us through a small reduction in combat radius which does not bring our own planes within unrefueled range (or within range with fewer refuelings). Moving it back a distance short of the next discontinuity in Russian capabilities, since it would not take us out of the range of other Russian aircraft, gains us less in reduced vulnerability per unit of the increased costs of our own increasing combat radius.
Examining in these terms the thirteen bases measurements for which are presented in section 6, suggests anomalies. The Moroccan bases, for example, appear to be on the wrong side, from our standpoint, of jumps both in our enemy's and our own capabilities. They appear to be just within unrefueled medium bomber range of the Soviet Union and satellite countries, and somewhat beyond our own unrefueled medium bomber range to various targets. The peculiar effects of this location are visible in the Moroccan sortie costs presented in section 13.
A game theoretic argument comes to mind in this connection. The jump discontinuities are an intuitively obvious consequence merely of the fact that an air force is made up of a relatively large number of aircraft of relatively few types—types being defined by range capabilities. But where will the jumps occur? (That is, what aircraft types will be emphasized?) How big will the jumps be? (How many aircraft of each type will there be?) These matters are subject to our prediction, but also to his control. To meet any move we have made in base location to take advantage of the expected composition of his air force, he may change the composition of his force.
Do we gain anything therefore by locating our bases in consideration of these points of discontinuity? We think so. For while the composition of his air force is subject to change, these changes are subject to constraints.
- For one thing, the composition of the Soviet Air Force is only partially determined by the disposition of our bases. The larger part is governed by other strategic and tactical uses, in spite of the fact that planes at any given time may be withdrawn from such uses for purposes of attacking bases. Locating bases in an efficient way with respect to this predicted composition means placing them efficiently with respect to the largest part of Soviet air. Or it forces a reduction in the efficiency of Soviet Air for other uses.
- The composition of the Soviet Air Force takes a considerable time to change. Three or four years hence (like our own, but perhaps even more so, since they have a smaller production potential) their air force will be made up in good part of the planes it has today.
- Changes are costly. New types mean large design and development costs, new emphasis in production mean large tooling and other starting expense. We gain something even if the Soviet Union counters our move and has to pay for it. It means less Soviet Union defense or attack capability in total.
The foregoing concerns the local criterion which is, of course, less important than the problem of the general course of diminution in Soviet capabilities with increasing distance. The following comments describe the various zones in turn.
Within a zone 350 nautical miles from the border of SU and satellite territory, SAC bases are open to attack by thousands of aircraft, mostly of fighter-type. A British study indicates that in strafing attacks against aircraft on the ground, a fighter has 0.5 probability of destroying or disabling an aircraft in a single pass. If SAC operating bases are located within this zone, they can expect continuous attack of considerable intensity. It might be noted that Air Force bases in East Anglia are close enough to this zone to encourage the use of range extension devices for fighters. This does not necessarily preclude the usefulness of refueling or emergency bases within this zone, but it makes primary bases here extremely doubtful.
None of the thirteen bases considered in Sections 6 and 13 are located within this zone, with the possible exceptions of Birmingham and Tokyo.
From 350 to 750 nautical miles, light bombers will present the greatest threat. One of the important factors, as yet unresolved, which will determine the level of attack within this zone, is the capability of SU light bombers to carry A bombs. Present indications are that this type of aircraft will be capable of carrying 5,000 pounds. In levels of active and passive defense included in the systems costs presented in Section thirteen, we assume that the SU will have A-bombs of this size. In any case, medium bombers will present the threat of A-bomb attack within this zone.
From 750 to 1,800 nautical miles, the SU will have to employ medium bomber against our bases. We have assumed that this force will be made up of TU-4's, and that there will be no heavy bomber force of any consequence. The level of attack as measured by sortie capability is expected to be about one-third as great as that in the 350 to 750 mile zone, while the HE dropping capability is expected to be about one-fourth.
Beyond 1,800 nautical miles the SU capability for sustained attack drops off sharply, since aerial refueling is necessary. However, one-way missions offer a threat of heavy one-time attacks.
Aircraft bases are subject to other than air attack. Mention must be made of the possibility of sabotage (wholesale and retail) and attack by SU regular forces (delivered by sea or air). This subject has been covered in considerable detail in Operations Analysis Report No. 6, HqUSAF, with respect to the UK. Need for the training of Air Force personnel in the use of small arms and for the maintenance of constant vigilance is emphasized in this report. It is conceivable that all of our forward overseas bases could be attacked simultaneously by a force of several hundred parachutists intent on destroying whatever aircraft, fuel, buildings and equipment were in place. On brief consideration it is apparent that bases located in Libya, Saudi Arabia and Thule are more subject to this kind of attack than those located in more protected areas. Thule, with an extremely low capability to recuperate, would be particularly susceptible in such an event. We hope to devote further attention to the subject over the next few months.
Defense and Expected Damage
Given the fact that we have bases located at various points throughout the world, wherever they are, it is vital that their vulnerability be taken into account. There is a growing awareness in the Air Force of the importance of considering Soviet air bases as a high priority target. Considerations of the symmetrical aspects of air war would suggest the importance of improving our own base defense. This is especially obvious if, as is widely assumed, the Soviet is to get in the first blows. While there is now a considerable Air Force interest in this question, very little thought has been devoted to its solution so far. How little is suggested by an inspection of existing base layouts and a reading of such Air Force regulations as the recent AFR 86-4 on the Master Planning of base installations and development and an AMC criterion for locating hardstands. Air Force Regulation 86-4 which applies to permanent installations both here and abroad, stresses in general the necessity for concentrating facilities, except for the normal fire safety clearances.
"a. Building Area. The building area should be planned to minimize the distance traveled by personnel in performance of their duties. Housing area for school troops should be located as conveniently as practicable to the school structures and technical area, and base personnel should be housed close to industrial, utility, and administrative areas. The relative location of transient aircraft service areas, base operations office, transient messing facilities, recreation building, exchange, and post office should be carefully studied. Consideration will be given to the maintenance of required fire breaks and building separations in all planning."
"b. Warehouse Area. Warehouse and storage areas should be located to minimize the amount of construction required for railroad spurs and access roads. Locations should be such that the railroad spurs and access roads will bypass built-up areas and avoid passage through runway clear and approach zones and any other aircraft safety zones. In many instances, it is advisable to locate the warehousing area adjacent to, or as an integral part of aircraft maintenance and repair shops and within the prescribed distance from main crash and fire station to avoid the need for additional fire stations."
Economizing on the number of fire and crash stations is a very doubtful procedure considering their cost as compared with the probabilities of bomb damage.
Just as AFR 86-4 stresses the importance of concentrating buildings to economize on construction and service costs, the AMC criterion for the layout of hardstands calls for the maximum concentration of parked aircraft "compatible with avoiding the detrimental effects of engine blast on equipment and personnel." The detrimental effects of bomb blasts are not considered.
We have made some preliminary analyses of base vulnerability along the lines indicated in Section 8 for a limited number of cases involving in particular the landing and take-off and refueling functions. We have done this merely to get some rough notion of the order of importance of base defense costs: or rather, the upper limits of their importance in relation to the range-dependent and other system costs which vary with placement of bases. Answers to these questions then, have relevance both to determinations of future base locations and the protection of bases in any given location.
At this stage it is necessary to observe about our assumptions that the base facilities, their specifications and their arrangements, the weapons chosen for their active defense, and the repair preparation levels, are being selected, not as the result of a weighing of a great many alternatives, but as a preliminary to it. The base vulnerability costs corresponding to the assumed mixtures are therefore to be regarded as hypotheses to be tested in the near future rather than firm results. In particular, our estimates of defense costs of primary operating bases (as distinct from secondary or refueling bases) in the various zones are extremely tentative. As will be made clear, very little work has been done on the crucial problem of the vulnerability of aircraft on the ground, as distinct from that of the base facilities. We are going through the base functions systematically, from the function of providing means for landing, take-off and fueling, to the storage and maintenance of aircraft and personnel. The first results concern the landing, take-off and fueling functions. However, these functions have an interest independent from the rest, since they are separable and, in fact, are separated in enroute and post-strike staging bases. Moreover, even in this early phase of our inquiry, judgments may be hazarded on refueling base defense in advance of judging the costs of primary operating bases which permit the comparison of aerial refueling and refueling on the ground. And with less hazard than is involved in judging the cost of defending primary bases.
Summary of Results on Runway and Refueling Functions
The results so far as the runway and refueling systems are concerned, are, in brief: (1) that they are subject to cratering but not to blast, (2) that, in the case of A-bomb cratering through ground or penetration bursts: (a) the bursts yield a rather high probability of damage, given the release of the bomb over the target, and (b) such damage, sustained, is by and large complete and permanent—not subject to repair at less than the initial cost or in less than the initial time; and (c) that, given the expected size of the Russian A-bomb stock pile, the probability that an A-bomb will be released over these targets can be made quite small by moderate expenditures for active and passive defense; (The limiting factor in Russian capabilities here is the Russian A-bomb stock pile, estimates for which we have borrowed from the Air Defense Study), (3) that in the case of high explosive: (a) by moderate expenditures in construction, equipment, and personnel we can be ready for quick repair of cratering damage at 10 percent and higher damage levels and (b) modest expenditures in defense by ourselves seem to assure high and in fact unfeasible rates of expenditure of Russian aircraft in order that they may, through pattern bombing and the like, secure any critical damage level.
Marc Peter has made estimates of the force requirements for HE cratering of runways and refueling systems. The following quotation summarizes the conclusions on requirements for runway damage. "Orthodox HE bombing for cratering purposes is an effective use of the munition but involves a much larger number of planes which become the critical element in this sort of tactics. On the basis of Eighth Air Force record data, the force required for a certain level of damage may be estimated. Two release altitudes are considered: 20,000' and 30,000'. The first with a CEP of 1,000' and a bomb pattern of 1,500' x 2,000'; the second with a CEP of 1,500 and a pattern of 3,000' x 2,500'. Aiming is visual and bomb runs are at 250 m.p.h. in close formation of 12 to 20 Afc's, each with a load of five tons (TU-4's). From test data the 500 GP fused .025 in hard earth and at release altitude and speed specified above, will produce on average a crater 14' deep and 600 sq. ft. in area or a volume of 100 cubic yards of displaced earth per hit. On a tonnage basis, the 500 GP is better than larger GP's. The size of the target is 8,000' x 400', including the two side shoulders and as a first approximation, critical damage will be set at a total cratering area equal to 10 percent of the target area or 320,000 sq. ft., i.e., 533 craters. From AFM 200-5, data sheets Nos. 8 and 9 this gives us a required number for a 50/50 assurance of 3,530 bombs for the 20,000' release and of 5,050 bombs for the 30,000' release, corresponding to 440 and 640 aircraft respectively, on target. To the number of sorties, additions must be made for gross errors, mission failures and other attributive factors."
Peter has supplemented these estimates with figures for 5,000 ft. altitude release. These are as follows:
J. J. O'Sullivan has gauged the effect of various levels of damage on our level of operation, considering substitute methods of operating, and the time and cost requirements for repair. See RM-730, "Time, Equipment and Costs to Repair Cratered Runways," and a forthcoming RM on repair and operation of damaged refueling systems. Some results of the first paper are summarized as follows. Three conditions of readiness and availability of construction equipment at the base were assumed. Condition A with about one-sixth of a million dollars worth of equipment, condition B with approximately one-third, and condition C with about three-fourths of a million dollars. Condition A allows the filling and surfacing of 77 cubic yards per hour; condition B of 507 cubic yards; and condition C, 1,225 cubic yards. The time to repair the runway with 10 percent damage would be about 400 hours, 145 hours, and 75 hours respectively. For medium bomber fields, the typical runway consists of a paved runway, usually 200 feet wide; shoulders about 50 to 100 feet wide located on each side of the paved runway; graded areas 50 to 100 feet wide located adjacent to the shoulders. The shoulders are stabilized to carry planes in all types of weather, while the graded areas are constructed to support planes in dry weather.
Limited operations are possible with only one 100'-strip, whether shoulder or runway proper, and if bomb distribution is random, one of the four strips is likely to have received somewhat less than one-fourth of the hits. Hence maximum immobilization time in the example above is a bit under 100 hours for condition A, 36 hours for condition B, and 19 hours for condition C. In other words, the above confirms WW II experience with airfields: that a large effort against them produces relatively little effective damage if the earth-moving equipment is available in sufficient number and appropriate size.
For the refueling apron Peter's summary concludes that the deliver effort for HE is extremely large, "If we assume that at least 20 per cent of the apron must be cratered, we need
craters and at 20,000 feet release altitude, 100 feet CEP, 2500 x 2000 pattern, a total of 6000 hits or 300 aircraft over the target. If, furthermore, the attack is not concentrated in time, the net damage effect to the apron is negligible."
On the basis of O'Sullivan's and Peter's work, it is possible to form quite reliable useful judgments about the landing, take-off and refueling functions.
Description of Refueling Base Assumed and Adequacy of its Defense
The vulnerability and operational meaning of damage to each base function leads to the examination of possible advantages of separating these functions with the idea of putting expensive, soft components to the rear, and cheap, hard components forward. The results of the comparison of refueling in the air versus on the ground presented in Section 12 indicate that bases which could serve solely as refueling points would be of value.
A refueling base must have facilities in order to provide three services to transient aircraft: landing and take-off, aircraft parking during refueling, and storage and loading of fuel. There are other functions that might be performed at such a base, including light maintenance, but such services are not essential to the refueling operation. In the aerial versus ground refueling comparison, a base capable of performing only refueling activities was considered.
In the discussion above, it is noted that each of the facilities essential to the operation of the refueling base is relatively invulnerable, or can be made so. However, for the short periods of time aircraft are on the ground at a refueling base, they are vulnerable to attack, and the design of the refueling base should be directed towards the reduction of this vulnerability. (Sec. 12 assumes, in addition, that fighter defense is flown in on a mission basis.)
The refueling base is designed around two principles—maximum dispersion and multiplicity of facilities against expected HE attack, and high damage repair capabilities. With the large number of refueling bases that can be made available, and the relatively low unit value of each, we have concluded that A-bomb attack against refueling bases can be ruled out within the period considered. For protection against HE attack, the least costly defense appears to be dispersion and multiplicity of facilities combined with a high recuperability.
This base, as described by J. J. O'Sullivan, is provided with two 10,000 foot runways, four refueling aprons widely dispersed, four widely dispersed underground tank farms holding 850,000 gallons of jet fuel each, four hydrant refueling systems, one servicing each refueling apron, a GCA radar unit, and community facilities for a complement of 150 men. A detailed listing of base facilities is found in Table 10-I. The new cost of this base is approximately $21,000,000 in an overseas area with construction costs comparable to those in French Morocco.
Thirty-eight of the complement of 150 men are assumed to be capable of operating the $778,000 worth of runway and apron repair equipment provided. With this equipment the vase would have the following recuperability.
|Percent of Pavement Cratered||Time to Repair (Hours)|
As is noted earlier in this Section, a usable strip of runway could be prepared in about one-fourth of the times listed.
We do not distinguish bases which serve as pre- and post-strike refueling points since the refueling function of each base is identical. It appears that there would be some advantage in providing this type of base with additional capabilities. Any added capability provided to the refueling base destroys the identity of the aerial vs. ground refueling operation presented in Section 11. The addition of light maintenance of the type described in the SAC mobility plan is a good example. Minor repair and adjustments performed at the refueling base should serve to reduce the abort and attrition rate after the refueling. The amount of maintenance to be performed at a refueling base depends on the length of time the aircraft would be forced to remain on the ground, the amount and nature of the malfunctions that can be expected at the base (presumably a post-strike refueling base possible would have more aircraft in need of repair than a pre-strike base), possible reductions in the abort rate as the result of advanced maintenance, and the cost of providing this capability. We have followed the SAC Mobility Plan in assuming the maintenance personnel and supplies would be flown to selected refueling bases just prior to a strike and that permanent assignment of such personnel would not be required.
One of the virtues of the refueling base as compared with operating bases is the low cost of multiplicity. A survey of existing and proposed overseas bases has indicated that there are a large number of bases which could be used as refueling bases without the impairment of their normal function. Moreover, it is possible to build up some facilities so that they are capable of joint intermittent or successive use for differing missions. We distinguish here among the following types of overseas bases that might be utilized:
- Existing SAC bases.
- Bases occupied by other USAF Commands and other services.
- Bases in secure and well-defended areas (UK).
- Bases in areas not very secure or well-defended (Turkey, Libya, etc.).
The feasibility of using SAC bases is apparent since the refueling operation requires facilities not contained on an operating base. Using bases of other Commands and services would generally require that additions be made to those bases.
One important possibility in this connection might be the building of primary operational fighter bases to a standard that would permit their use for SAC refueling purposes. This involves building a longer, wider, thicker runway, constructing larger facilities for fuel storage, adding a few more hydrant outlets, and making a few other adjustments.
Such standardization of the fighter-bomber base at the level of the medium bomber base, (at least for the landing, take-off and refueling functions) would add a great deal to the flexibility of SAC. Moreover, for bases within the range of enemy fighter aircraft, for any refueling to be done, it would provide the fighter defense that seems needed at moderate extra cost. To make the base available to SAC as a refueling station up to the full standards enunciated in the Facilities Requirements Handbook, would require a little over $8,000,000. It would cost an extra $4,000,000 more to bring the maintenance facilities up to medium bomber standards. The political considerations mentioned earlier in Section 4 which sometimes make the mission of the base a sticking point in negotiation, suggest that standardizing the fighter bomber facilities at medium bomber levels would permit exploitation of later removal of mission restrictions.
The unattractiveness of refueling bases as targets for A-bomb attack plus the invulnerability to HE attack makes for a small active defense requirement. However, an undefended base might be subject to accurate low-level attacks on such critical facilities as pump stations, and generating plants. For this reason the cost of employing six 40 mm. mounts against daylight attacks is included.
This is an active defense level calculated to keep attacking TU-4's at an altitude of 5000 ft. or over. The type of defense assumed is not being recommended. We are quite certain that detailed analysis will yield another recommendation; however, the gross figures do suggest that this magnitude of defense cost would be adequate to keep the required number of refueling bases functioning.
Beyond the fighter zone the enemy will have aircraft available in a rather limited number. This number, of course, must be distributed among other high priority tasks, such as strategic air attack upon the U.S., strategic attack on our major allies' industrial targets, and strategic support of the ground attack on Western Europe, to say nothing of attack on our primary operational bases. Moreover, during the course of our own strategic campaign the force available both to ourselves and to the enemy will diminish with attrition.
We will assume for the purposes of the air-ground refueling comparison in Section 12, that (1) we have 100 to 200 refueling fields available for SAC use in total at the start of the campaign, of which, say, 50 are needed at the beginning of the campaign and somewhat less as our own forces suffer attrition; (2) that we have two runways per field, (3) that inexpensive modifications (described later in this Section) in the arrangement of the hydrant outlets and the refueling apron are made with the result that the force requirements to keep these inoperative are larger than the force requirements for putting the runways out of commission, (4) Assume that the fuel storage is dispersed locally and that all of it including jet fuel bulk storage is kept underground, which also of course makes it easy to hide. (It appears that splitting the fuel into numerous small tank farms, dispersing them, sinking them underground and hiding them would render the fuel storage practically invulnerable.) The cost of doing this we have seen is very reasonable in relation to systems costs.
Since these last three elements are the only elements of any importance at risk in a refueling base, our last assumptions mean that the force requirement to put out the two runways in a given field are the minimum force requirements.
We assume further, (5) the condition of maximum readiness to repair referred to earlier (Section 10) and (6) a minimal Ack-ack active defense, just enough to assure that the enemy will find it too expensive to go below 5000 feet in altitude. On the basis of these assumptions the vulnerability estimates of Marc Peter for the runway establish a force requirement for equipment which exceeds the number the SU is expected to have by a very great amount.
On our assumptions the enemy can eliminate 50 to 150 fields at the outset and something over that before the end of the campaign. Let us take the 50 field elimination. This means keeping 100 runways out of operation. To do this would require over 10,000 TU-4's attacking every day or so, which of course is a very considerable multiple of his total strategic carrying capacity at the outset, before he has suffered attrition. (As both forces of aircraft sustain attrition we can afford to lose more fields and he is less able to eliminate them.) Requirements would be tripled for the 150 field case.
This line of reasoning can establish also that an adequate number of refueling bases should survive A-bomb attack. Here the limit is in the A-bomb stockpile, and the likely proportion of it that could be exclusively devoted to our refueling stations in the medium bomber range.
Other Functions at Risk on the Primary Base
We have done as yet very little with regard to the vulnerability of other base functions to attack.
To provide some notion of the base elements other than aircraft that are at risk in a primary operational base, the detailed list of facilities required for a medium bomber base has been costed. The facilities requirements are taken from AFMAI - USAF Installation Facility Requirements, July, 951. These elements have been sorted into four broad categories of function and a residual. The total value of installations in place comes to about $50,000,000.00, half of which is for personnel facilities, 17 percent for landing and take-off, 10 percent for fueling, and 15 percent for maintenance.
In figuring the costs of basing SAC in various locations, in the next phase of our inquiry we expect to consider incremental costs, not only in terms of a systematic survey of existing facilities and their conversion costs, but also in the sense of the marginal costs of joint or intermittent use with TAC and other commands. In this connection the analysis made so far of facility requirements as well as base defense requirements suggests the possibility of considerable savings.
Aircraft parking is particularly important to consider since aircraft are apparently the most valuable and vulnerable element at risk on a primary base.
In the absence of any extensive reliable data on the vulnerability of aircraft on the ground to HE and A-bomb attack, we have assumed on the basis of the fragmentary information now available that, if unprotected, they suffer minor damage at about 3 pounds per square inch overpressures and major damage at about 6 psi. For a 20 KT A-bomb burst the 6 psi point is approximately 6400 feet from ground zero, while the 3 psi point is at 9700 feet. For a 100 KT bomb the 6 psi point occurs at 10,800 feet, while the 3 psi point occurs at 16,700 feet. Given this assumption, a properly placed 20 KT bomb would suffice to seriously damage or destroy all of the aircraft on an airfield with no provision for dispersal, while a 100 KT bomb would destroy all of the aircraft on an airfield designed for dispersal against HE attack. The levels of active defense presented in section 12 are based on this assumption.
It appears that it may be profitable to attack primary bases with HE except for those airfields to be reached only by medium bombers where strong defenses are in place, or where one-way missions are necessary. The importance of dispersing maintenance facilities, and POL and spare parts storage at overseas operating bases is apparent.
Reducing Vulnerability of Base Functions
Reduction in the vulnerability of a base can be obtained by the application of two kinds of defense: active (guns, missiles, interceptors), and passive (dispersion, camouflage, shelters, smoke, dummy aircraft, and preparation for repair of damage). A combination of these defenses can be chosen such that the total of defense costs plus the expected loss from damage and interruption of base functions is minimized. Active, as opposed to passive defense, serves not only to destroy bomb carrying aircraft, but also prevents aircraft from making return trips. For bases located in areas where one-way missions alone are possible, the threat reduces to relatively few, although intense, attacks. In these areas, passive defense appears to be much more economical than active. However, such passive defense measures as dispersal need study in connection with both overseas and domestic air fields.
Work being done at the present time at RAND on the dispersal problem considers three degrees of dispersal: (a) world wide dispersal, (b) an area dispersal involving the multiplication of base facilities, one to a squadron, and their separation by anywhere from 5 to 100 miles, and (c) a local or "microscopic" dispersal which involves the spatial separation of the elements on a single base.
The world-wide dispersal problem has been discussed in earlier sections of this paper and is one of the principal objects of our inquiry. The area dispersal study is presented in D(L)-1064 which deals with the costs of separate operation of a B-47 wing overseas. This study, which omits active defense costs, found that personnel augmentation of 20 percent over the normal wing complement would be necessary for dispersed operations. Installation costs were increased by 55 percent, but the four-year cost of the system was increased by only 11 percent. The effect of this dispersal, neglecting problems of active defense, is to decrease the vulnerability of a wing to A-bomb attack to approximately one-third of the non-dispersed value, and also to reduce expected losses to HE bombing. From the microscopic studies, it appears that a moderate local dispersal will diminish the vulnerability of a primary base at least to HE attack and possibly to A-bomb attack and will decisively reduce the vulnerability of a refueling base.
For certain primary base functions reduction in A-bomb vulnerability equivalent to that obtained on squadron dispersal can be achieved by locally dispersing those facilities radially outward a distance equal to 1.16 times the lethal radius of the bomb expected. For protection against a 100 KT bomb minimum radial dispersal of approximately three miles is required to obtain this degree of invulnerability. It appears that the cost of such dispersal is no greater than that of area dispersal.
Some base functions can be locally dispersed with only minor increases (considering the scale of total systems costs and the probable gains) in installation or operating costs. A relocation of the refueling facilities in which the refueling apron and fuel storage was separated into four parts, and located near the ends of the runways, resulted in a 5.7 percent ($2,564,000) increase in installation cost for a medium bomb wing. The cost of additional taxiways comes to $1,910,000 while the cost of additional fuel facilities was $654,000. One of the conditions we imposed on this modification (for reasons that will be made clear) was that no increase in taxiing result. This can be seen from the sketches:
With the modified arrangement taxiways can be used as emergency runways, each 10,000 feet by 75 feet. With stabilized shoulders on either side of the taxiways the usable width would be 125 feet.
Many questions of an operational nature remain to be answered. One common criticism of wide dispersal is the high consumption of fuel occasioned in taxiing from parking or refueling areas to the end of the runway. We imposed the condition of no increase in taxiing on the apron dispersal redesign for this reason. However, many alternatives appear available, the three most popular being: (1) tow aircraft to the end of the runway, (2) provide external fuel tanks to be dropped at the end of the runway, and 93) station fuel trucks at the end of the runway to top-off fuel tanks after taxiing.
Another stated objection to wide dispersal is the need for centrally located maintenance ramps. If there is no alternative to this method of maintaining aircraft, then it might be necessary to duplicate facilities of this sort. In any event, aircraft could remain in dispersal areas while not undergoing work. A large concentration of aircraft at ramps would defeat the purpose of dispersal.
We recognize that in many areas there are constraints which prevent wide local dispersal; unsuitable terrain, increased vulnerability to sabotage, and non-availability of surrounding land are three obvious constraints. As a possible alternative to wide dispersal, we are examining the effect of shelters against bomb blast not only for areas where wide dispersal is impossible, but as a more economical means of protecting base functions. Two cases are under examination: uncovered revetments and underground hangars.
Dispersal of the remaining base functions—housing, maintenance, and storage—appear to offer no major difficulty. The major cost increase resulting from dispersal of these facilities would probably be for transportation equipment and personnel to support a high intra-base transportation requirement.
Levels of Defense Assumed in Cost Calculation
The system costs presented in Section 13 are for a mix of active and passive defense which provides for passive defense through separate squadron bases (not locally dispersed) for bomber wings located in the Northeast and Northwest sections of the ZI, and all bomber wings located overseas. Active defense consisting of all-weather interceptors equipped with the MX-904 and appropriate GCI radar coverage has been provided. The Defense Study shows this to be the most effective defense weapon that will be available in quantity by 1955 for this purpose. The cost of weapons designed for local defense to low level attacks has not been included in the primary base costs, although provision for low level defense is included in the refueling base design. Fighter defenses have been distributed according to the expected level of attack as follows: those bases open to attack by fighters have three interceptor wings per bomber wing, bases located in the light bomber zone have two interceptor wings per bomber wing, while bases in the medium bomber zone (including those within one-way mission capability) have one interceptor wing per bomber wing. These are not recommended defense levels; they are chosen as representative of the magnitude of the expected effort. A more accurate exchange ratio between active and passive defense needs further work. The mass strike kill potential of these defenses appears to be sufficient to insure the survival of at least 80 percent of our bases, when there are 120 bases (30 wings of four squadrons each) located within range, and SU capabilities are as assumed in Charts I and V, Section 9.
The only bases considered in Section 13 which possibly are within fighter range are Birmingham and Tokyo. One wing indigenous interceptor defense per bomb wing was assumed free for bomb wings operating from these areas. The effectiveness of this defense against strafing attacks by fighter aircraft is uncertain. The two bases within the ZI that were studied, Limestone and Spokane, were charged with the cost of one interceptor squadron each. Air Defense Command units are assumed capable of providing the remaining defense required. Although we have not included an example of bomber operation from the interior of the ZI, we feel that the cost of active base defense would be sharply reduced due to the Air Defense Command, and the long warning time.
If all-weather interceptors, or the MX-904, are not available in quantity for the defense of SAC bases, then higher defense costs would be entailed. Also, the kill probability against jet type light bombers will doubtless be lower than that against the TU-4.
The defense levels described were determined considering the specific world-wide distribution of base functions to be defended involved in our air-to-ground refueling comparisons of Section 12 and primary base location comparison made in Section 13. These comparisons do not present all of the major alternatives for the world-wide distribution of base functions in peace and war.
Distribution of Base Functions in Space and Time
If we consider just the broadest alternatives for locating strategic air base functions—in the Zone of the Interior or overseas, in peacetime or in war—a half-dozen non-trivial possibilities present themselves. Take four principal groups of base functions: a) landing, take-off, and fueling, b) parking of aircraft and housing of crews and c) light maintenance and d) heavy maintenance. First, one possibility is to locate all of these in the Zone of the Interior both in peace and in war. Because of the range limitations of likely future bombing systems this means in practice for a long time to come dependence on aerial refueling to extend radius; this would be necessary in order to reach any significant proportion of the strategic targets and it does not suffice for all. Second, at the other extreme, we might locate all of these functions overseas in peace as well as in war. A third variant would modify the first by adding a system of secondary ground refueling bases, devised, like aerial refueling, exclusively for the purpose of range extension. As a fourth, to exploit possible savings in battle attrition of aircraft crews, we might add to this secondary refueling base system, a light maintenance function. Fifth, we might follow the practice of locating, except for maneuvers, all four groups of functions including the storage of aircraft and personnel, in the Zone of the Interior in time of peace and in time of war shift all four functions overseas. (The SAC Mobility Plan involves following the fifth alternative of ZI peacetime basing and, for a majority of its force, overseas basing in time of peace; and the second alternative of overseas basing both in peace and war for the remainder. Other proportions might be considered.) In this fifth case, the secondary overseas base systems are potential operating bases involving continued storage of aircraft in wartime as distinct from refueling and light maintenance stations. A sixth alternative, a minor variant of the fifth, would keep all heavy maintenance back in the Zone of the Interior, while basing the other functions forward in time of war.
The most important specific advantages of base systems, such as 1, 3, and 4, which store aircraft back in the ZI during the war period (with or without secondary overseas bases) consist in the reduction in vulnerability throughout the campaign of this most valuable and easily damaged element at risk in a bombed air base. Their greatest disadvantage is the low sortie rate entailed by the extended mission distance and mission time. Wartime primary basing overseas (2, 5, and 6) involves the opposite virtues and defects. Mixed systems like 5 and 6 which shift the storage of aircraft overseas at the outbreak of war, lower vulnerability to the initial enemy blow though not to his continuing attacks, and, like 1, 3, and 4, enjoy lower peacetime operating costs and obviate the political difficulties connected with attempting to station large numbers of personnel overseas in time of peace. On the other hand, as compared with peacetime basing of aircraft overseas, such systems involve some delay in starting our own steady strategic campaign and a considerable cost in airlift.
In this paper we present cost analyses for base systems of the first three types. Section 13 considers systems involving primary bases overseas in peace and war as compared with ZI peace and wartime primary base systems. Section 12 considers the economies to be gained by adding a system of overseas ground refueling bases.
Comparative Costs of Aerial and Ground Refueling 
The Strategic Air Force expected in 1955 and 1956, if it is based in the Zone of the Interior, will require refueling either in the air or on the ground to hit the targets presently contemplated. This is apparent from the expected combat radius of the B-47 and the B-52 and the tables of critical distances presented in Section 10. Refueling, either in the air or on the ground, is in any case an important device for decreasing the size, expensiveness, and vulnerability of the combat aircraft. Neither air nor ground refueling, of course, does anything to improve the sortie rate. (In fact, rendezvous time uses up flying hours.)
In the case of air refueling, one must consider the extra costs of the tanker system, the probable costs of difficulties of rendezvous, and, in particular, of post-strike rendezvous by battle-weary crews. There are other limitations to the advantages to be gained by aerial refueling. The method yields diminishing increments in radius with increasing numbers of refuelings as the extra tankers must themselves fly further out and back. In fact, for any given pair of bomber-tanker types there are absolute limits of range extension, and these are shortened by the necessity of avoiding proximity of rendezvous to enemy territory. For the bomber-tanker types to be available in 1955 and 1956, this range limit is short of a good many targets.
In the case of ground refueling, one must take into account the extra costs of adding refueling bases in quantities large enough to assure survival of the requisite number from probable attacks for given levels of active defense. And we must include the costs of refueling-base defense. Ground refueling has less flexibility in some significant respects than air refueling, but the amount by which a simple ground refueling extends range is, in general, greater than that to be accomplished by one air refueling, and this is particularly true as the number of refuelings increases.
We have made a comparison of the sortie costs from Limestone using the B-47 aircraft against our target group one which includes Leningrad, and the B-52 against target group three which includes Kharkov. The results of our first calculations here strongly suggest the economy of minimum refueling bases as opposed to tankers for the purpose of range extension.
In general, we have attempted, by a variety of calculations, to load the case in favor of aerial refueling. (1) In all the calculations it was assumed that the probability of a rendezvous was unity. (2) In the case of ground refueling we have recognized throughout the increase in combat radius through dog-legging implicit in refueling at any base not in line with the primary base and target. In fact, since the refueling base locations were not selected optimally, we have overstated the combat radius needed in the ground refueling case. On the other hand, in the case of aerial refueling the primary base-to-target distance has been measured without the dog-legging that SAC regards as necessary to assure a rendezvous over identifiable regions. (3) In addition to ignoring the necessity for identifiable rendezvous points we have ignored as well the limitations on the selection of optimal air refueling points imposed by the proximity of the rendezvous to the Soviet border. In choosing the ground refueling bases, however, we have operated under the constraint of keeping them out of enemy fire range. (4) We have not given the ground refueling base systems credit for inheriting any existing installations or any existing defense. These are all costed new. In fact, our current investigation indicates that the incremental costs of a ground refueling base system will be considerably lower. There appear to be a considerable number of economically usable existing bases capable of reactivation for exclusive use as SAC refueling stations, and there are considerable possibilities of intermittent use by SAC for refueling purposes of TAC, MATS, and other such bases. (5) Target groups one and three, which were taken for this first ground-air refueling comparison from Limestone are among the closest of the target groups to Limestone. Therefore, the diminishing rate of increase in range extension by air refueling does not operate against air refueling as severely as it would for more remote targets. For more remote target distances, the superiority of ground refueling would be even more evident. (6) We have designed a ground refueling base principally for the analytic purpose of this comparison with air refueling. For this reason we have excluded maintenance, additional medical facilities for the crews, etc. It is possible that by adding light maintenance, for example, a more than equal return might be obtained by reducing losses in aircraft and aircrews over a minimal facility. In other words, a minimal facility is very likely not optimal. If so, a less rudimentary refueling stop would show more marked superiority to air refueling. (7) In some calculations we have assumed that only one tanker is required to refuel three bombers, and in some we have assumed that as many as four advance refueling bases with eight regular runways and 16 emergency runways will be required per operating base in order to assure accomplishment of the refueling. (8) We have amortized the bases in four years as well as in ten. (9) The costs of defending the refueling base are included at something like more than twice what we expect will be adequate.
In spite of all this loading in its favor, in no case does air refueling come off as well as refueling on the ground. The results are presented in Chart 12-I.
Several cautions are to be observed in interpreting this comparison. (1) The comparison bears on the question of aerial refueling as a competitor and universal substitute for ground refueling. It indicates strongly that it is an expensive substitute. (2) But this does not speak at all on the important use of aerial refueling as a supplementary device providing flexibility and insurance against the loss of particular bases. In fact, we have no doubt at all about the great importance of aerial refueling here. (3) This is particularly so in the light of the development of the self-refueled bomber—the B-47 refueled by the KB-47, the B-52 by the KB-52, etc., with quick convertibility from tanker to bomber use and vice versa. (See our comments in Section 7-C.) Given the success of its development, loss of bases would mean only a reduction in the bomber force usable against a set of targets, not that we would be unable to hit the targets. On the other hand, exclusive or predominant reliance on aerial refueling with its high yearly operating costs, involves a much more considerable and less remediable reduction in the effective force of combat bombers purchasable with a given budget. Refueling bases cannot be built as quickly as bombers may be converted to tankers; and they have a low operating cost. (4) The comparison deals explicitly only with enemy attack, not with the possibility of the loss of bases through political upsets before the outbreak of war. However, the number of refueling bases in politically distinct areas which are supportable by the expenditure of considerably less money than air refueling seems quite large enough to offer assurance of surviving peacetime political upsets as well as wartime enemy attack. (5) The estimate of vulnerability of the refueling base functions which are used, are based on VIIIth and IXth Air Force experience during WW II and undoubtedly requires adjustment. (According to Mark Peter, Jr., developments in the last year in the design of HE bombs permit closer packing in bomb bays with some resulting savings in the aircraft force requirements to do a given job.) However, the differences shown appear gross enough to survive any likely alteration in these estimates.
Primary Base Location and Air Refueled Sortie Costs for 13 Bases
A. Taking the B-47 and the B-52 in 1955–1956, systems costs have been estimated for each of the 13 bases. The costs have been estimated roughly, in a manner more or less commensurate with the coarseness of our distance measurements. Stock level requirements are varied with the distance from the ZI. That proportion of theatre support costs attributable to bomber wing operations is included on the basis of a theatre support force as described in WPF-50(A). The personnel replacement rate is assumed to be identical for all wings on the assumption that the rotation time equalizes turn-over throughout SAC.
Base costs have been amortized in ten years and other capital items in four, and the assumptions of the earlier studies such as the Multiple Strike Analysis to the ratio of tankers to bombers have been used. (One tanker for a once-refueled bomber, two tankers for a twice refueled bomber.) The combat radii have been measured, as indicated in Section 6, without dog-legging, and we have assumed, as in the preceding section that air refueling takes place optimally, that is at the point yielding maximum range extension, neglecting considerations of reducing penetration, proximity to enemy territory, and securing an identifiable place of rendezvous. A few, though not all, locality factors have been considered in making these estimates. Specifically, the free defense available in the UK, Tokyo, and the ZI, has been considered; personnel augmentation has been allowed for in Thule and Alaska, and adjustments have been made for differences in construction cost throughout, on the basis of the usual Army Engineer factors. However, construction has been costed new in all cases, and for example, in the Arctic, the extra costs of training per person, the reduced sortie rates per aircraft, problems of terminal logistics, and other locality costs, have not been taken into account.
Airfield construction costs are measured on the assumption that squadrons are dispersed one to a base. In addition, we have computed installation costs assuming the considerable local dispersal of the apron and the refueling system, and the extensive use of revetments and other passive defense measures previously described. In addition to these passive defense costs, very considerable sums have been included for active defense costs. For example, in Alaska, active defense per bomber wing is taken at a level of over a billion dollars in a four-year period, and in Tokyo and Birmingham where we suppose that one of three fighter wings is free, the four-year active base defense costs are computed at over one-half billion dollars. However, while these primary base defense levels are considerable, we do not at present know whether they are inadequate or excessive and, as we have made clear, we will not know this until we have learned more about the vulnerability of aircraft on the ground. While we have achieved fairly reliable judgments about the limits of vulnerability of the landing, take-off and refueling functions, this is not the case for other primary base functions such as aircraft parking.
B. Sortie Costs of the 13 Bases. The results of the first calculations are presented in Charts 13-I to 13-IV, and similarly in Tables 13-I and 13-II. The relative differences in sortie costs are strikingly large. Some brief observations are in order about these charts. (1) The place names "Cairo," "Karachi," Dhahran," etc., in good part, indicate areas rather than individual sites. (2) From the cost comparisons shown, it appears that there are no universal base areas equally good against all targets, although the Near Eastern bases are good for a very large proportion of the industrial targets, and, considering the distribution of targets within Soviet and satellite boundaries, this superiority will very likely be more marked when the effects of penetration are considered. (3) The ZI and the Arctic overseas bases appear to be particularly high in cost. (4) In the case of the Arctic bases, their inferiority will appear larger when some of the locality factors presently omitted are taken into account, in particular, the degradation in sortie rate attributable to Arctic weather. (5) The two hypothetical counter-air targets in the extreme northeast of Russia which, as we have explained earlier, we chose precisely to display Fairbanks and Thule to their best advantage, do have this effect. Among the 13 bases considered, Thule ranks second to Keflavik against the Lena River target area, and Fairbanks ranks first against a hypothetical target on the Chukotzki Peninsula. However, it is probable that Spokane will appear better than Fairbanks when such locality costs as the effect of weather on the sortie rate and the terminal transport problems at Fairbanks are taken into account. On the other hand, a shorter range, less vulnerable bomber than the B-47 might be used from Fairbanks against this one target area for which it appears to have an advantage; and this might better its position. (6) Consideration of a more catholic range of bases as well as targets will naturally affect these rankings.
C. Lowest Sortie Cost Complex. If we chose a lowest sortie cost base complex by assigning each of the ten industrial target areas to the area which can mount sorties against it most cheaply, we obtain a smaller list of five overseas areas out of the 11 overseas and two ZI areas considered. (See Table 13- .) This complex of five overseas base areas might be compared with the ZI base complex consisting of Limestone and Spokane. When we assign the ten industrial target areas to Limestone or Spokane, according to which has the lower sortie cost, the weighted average cost per sortie amounts to some 12.7 million dollars. This 12.7 compares with 1.2 for the lowest sortie cost overseas base complex. This difference of more than ten to one may be attributed to three causes:
First, the difference in sortie rate: The weighted average mission distance for the Limestone-Spokane complex amounts to 4,000 nautical miles; for the lowest cost overseas base complex it is 1,460 nautical miles. On the assumption of a constant aircraft utilization, this means the ZI base sortie rate is a little less than 40 percent of the overseas base sortie rate.
Second, the number of refuelings required: The overseas base complex chosen required no refuelings at all to reach the industrial targets. The ZI base complex, on the other hand, even under the favorable assumptions made in measuring combat radius, required an average of one and one-half refuelings. This difference would be increased by a more realistic consideration of the flight profiles required to accomplish the aerial refuelings. (Such consideration would also worsen the sortie rate difference.)
Third, the use by the ZI base complex of the B-52 as distinct from the B-47: Part of the difference in sortie costs is attributable to this. The systems cost per aircraft of B-52 systems is roughly twice that of B-47 systems. The consideration of attrition of aircraft over enemy defense would probably increase the difference shown since the B-52 is not only more expensive, but perhaps also more vulnerable.
The observations are, of course, tentative, and a number of cautions are to be observed in interpreting them. First of all, we have done nothing so elaborate as to run a campaign analysis. This would enable us to determine the cost to destroy targets; therefore the force requirements, and total number of sortie and the number of bases needed for this purpose. In such a campaign analysis, a specific base location or specific base development would be evaluated in terms of whether it resulted in net reduction in the total cost to destroy a specified set of targets. A base location, for example, will have this result when there is a subset of targets which it can destroy more cheaply than any of the alternative base locations. This last criterion is, however, incomplete, unless the costs considered take into account not only the cost of the specific installation itself and its own defense, but its value as an insurance device and its contribution to the passive defense of the entire base system. If we consider this, we are likely to build some bases which are not individually best for attacking any target subset, but which, though they contribute less than the best, supplement these best bases. They make a net contribution, considering both cost and effectiveness, to the base system as a whole. This sort of choice of an entire base system adequate to perform the mission of the Strategic Air Force can be made firmly by considering not only a long list of base alternatives, but also by extending the analysis to include other costs of target destruction. Second, consideration of the effects of attrition of aircraft over enemy defenses is likely to affect these comparisons in several opposing ways: a. The larger aircraft used from the remote bases are more vulnerable both in the air and on the ground. b. It appears possible to reduce penetration distance with resulting savings in attrition more easily from the overseas complex than from the ZI. c. On the other hand, the sortie-rate effect as was mentioned earlier will be diminished when we consider attrition. Third, the comparison, of course, is qualified by the uncertainties of the primary base defense assumptions entailed by the state of our knowledge about the vulnerability of aircraft on the ground. For this reason in particular the differences shown in this section in the location costs of primary bases are less reliable than the comparison in Section 12 on air versus ground refueling. Fourth, we have compared these primary base locations assuming air refueling. As Section 12 suggests, the use of a ground refueling system might have a sizable effect on primary base location and is important to examine a combination of primary bases in the ZI and ground refueling bases overseas. similarly, it is important to examine the other alternatives presented in Section 11 which would vary base location in peace and in war. The results of Sections 12 and 13 make it appear that some variety of overseas base is economic, but the investigation has not proceeded far enough to determine which.
Questions for the Next Phase
A concluding section with this title should be either redundant or a summary: the paper as a whole is intended to pose and orient problems for the next phase. But it may be helpful briefly to make explicit some of the lines of application and testing indicated. This is particularly so since not all of them can be followed in the next few months.
Penetration and Primary Base Vulnerability
Two of the largest gaps in the analysis so far concern the effects of penetration and the vulnerability of aircraft on the ground. Until the latter gap is filled, comparisons of sortie costs, as influenced by primary base location, must be quite tentative. An extension is needed of the vulnerability and defense analyses which have been performed for landing, take-off, and refueling to the primary base function of storing aircraft.
From what has been said previously, it is also evident that the effects of penetration may bear strongly on the systems costs of various base complexes.
Future Bombing Systems
For the purposes of the 1955–56 comparison of base locations, the actual bombers scheduled to be operational in large numbers in 1955–56 — the B-52 and the B-47 — are obviously the most relevant. To this should be added whatever missiles promise to be operational in any significant quantity at that time. For later periods the type of aircraft that might be operational are not fixed and here the generalized bomber studies of the sort referred to in Section 7 are relevant. This is so especially because there is an interplay between base design and aircraft design. As was mentioned earlier, a base determination might influence aircraft design itself.
In Section 7 we used bomber capabilities analyzed in R-171. This was a matter of convenience for the purposes of illustration. We hope to use the results of the intercontinental Bombing Study as well. In the period 1955–1960 the importance of guided missiles of course, grows and should be considered in determining a base system. On the other hand, nuclear-powered aircraft which are very frequently mentioned as making overseas bases unnecessary for strategic air attack are not expected to be operational in number until considerably after 1960, or 1961, which is the limit of our own interest.
Interdependence of SAC, TAC, ADC, etc.
While in this paper our interest has been centered on strategic bombing bases, we have had to consider continental defense and ground force matters where they affected our problem. First, our assumptions as to base defenses required were founded on estimates of enemy attack capabilities and these, in turn, were made in recognition of the fact that we will be fighting one enemy with limited resources to be distributed among several uses—defense against strategic bombing attacks, ground attack in Europe and elsewhere, and strategic bombing of our industries as well as of our air bases. The estimates of base vulnerability were founded on predictions as to the total number of aircraft the enemy would have available for HE attack and the total number of A-bombs he would have in stockpile; but also on the other uses which he has for these. If he should spend more of his A-bomb on our air bases than is economic for him, that is, if he does this by diverting them from more damaging use against the continental United States, then our bases will have contributed signally to continental defense. For the tentative conclusion suggested in Section 10, fortunately only the very crudest judgments on these points were needed. Second, our own resources are distributed among several uses and our own strategic air bases, for example, have to be viewed in the context of the existence of the North Atlantic Treaty and the base structure it implies. For such reasons we have begun to consider problems of medium bomber-fighter bomber base interconvertibility and to see how importantly they bear on our problem.
Here again it is obvious that there is some interplay. Our target objectives shape our base distribution; but it is also true that considerations of the accessibility and the cost of destruction should influence the targets we choose. Considering the extra cost to go after them, some Far Eastern Russian targets, for example, may not be worth the bother. The target systems should be reviewed in terms of base distribution and weapon capabilities. As in the other tempting possibilities of digression, our own interest is limited by a strong focus on base choice. Any target system recommendation that might emerge would be a by-product. On the other hand, we do have a limited interest in order to insure the soundness of our base choices. Some rough sensitivity analyses or summary judgments should be made. So far we have used for the most part the industrial target system developed for MACS by Emil Lee. It would be good to see how the combat radii and penetration distances which figure critically in our study might be altered by the use of other target systems, in particular counter-air targets.
Old and New Bases — Enemies, Allies, Neutrals
The measurements in Section 6 of the critical distances for the ten existing bases and specifically their base-to-border distance measurements are made on the estimates of probable political alignments at outbreak described in various government documents stating the views of the Department of State, Department of Defense, and CIA. One test that could be made would take alterations in the doubtful cases in the configuration of enemies, allies and neutrals at outbreak. A second test that might be made probes the sensitivity of base location to the changes in the Soviet and satellite border that might take place during our strategic air campaign. For this purpose two plausible setups should be tried: The first would take the boundaries of the Soviet and satellite powers at various times during the campaign as they are projected in the Medium Term Defense program or the Joint Outline War Plan, since these plans apply to the 1955 period and in a sense represent the limits of containment that it is hoped will be achieved through NATO and the mutual assistance program. The second would take the pessimistic assumption that the eighty billion dollars or more that is planned to be spent in these programs will have been of no use at all, that in short, the boundary changes after D-day assumed in the current Emergency War Plan for 1951 will be the actual boundaries in 1955 as well. Some material has been gathered for both sorts of tests. This material has relevance not only to the selected bases dealt with in Sections 6 and 13 but of course, most importantly, to the evaluation of a more extended range of possible new base locations.
Alterations in Base Processes
The first such alterations that come to mind are inventions and innovations. By comparison with the attention given the weapons and their carriers, a rather slim research and development effort appears to have been devoted to air base processes. And the processes currently used bear evidence of a certain lack of inventiveness. None the less, there are a number of innovations in various stages of development that are capable of drastically altering such important base parameters as the size, dispersability, construction time, repair time, portability, salvageability, and adaptability to varieties of sites of various base facilities. And these innovations affect not only the function of these facilities but the performance characteristics of the planes. The zero-length launcher which might be substituted for take-off runways and the short pneumatic landing mat which has been developed and tested by the British, might substantially affect every one of the parameters listed. The intercontinental bombing study has indicated the importance of this innovation for weight reduction of aircraft through the elimination of landing gear. It also obviously has a very sizable effect on such matters as base defense. Such innovations as tracked landing gear, have a less fundamental character but are also prodded by problems in base processes. In the field of ground refueling systems we have come across a number of proposed alternatives that might affect the base problem and that are worth looking into. But a fresh look at all the base functions appears to be needed. Technical development here has lagged. It is important to examine these functions in a connected way. (The pneumatic landing mat must be considered along with all the components of the refueling function, etc.)
Apart from new inventions in base processes it is good to keep in mind the possible use of such things as seaplanes which also would drastically alter the configuration of the problem. (This example has been suggested by Bruno Augenstein.) Seaplanes would mean quite different location possibilities, landing-takeoff and parking methods and would affect both initial cost and base vulnerability. The alternative of carrier basing also comes to mind and is worth testing.
Keeping the Problem Manageable
The base problem, as we have seen, has natural and intrinsic connections with such problems as aircraft design and target selection. Moreover, the strategic air base problem is obviously related to problems of continental defense, tactical air base location, and a host of other Air Force activities. None the less, it is not feasible to say everything at once and it is feasible to focus on one part of the strategic air base problem, dealing with the others only in the broad terms necessary for solution of the problem to which we are addressing ourselves. This is not only feasible; it is necessary if we are to get anything done.
The lines of work in the next few months may concern both macroscopic questions (for example: In what countries would it be best to locate new bases for our expanding Air Force?), and microscopic ones (for example: Given a base within Soviet medium bomber range, how is it best to position installation elements needed for refueling, landing, take-off, etc., so as to minimize base vulnerability and defense for given levels of cost and operational efficiency?). The two sorts of questions are related and we have considered them together in the foregoing. They are, however, partially separable. To answer the gross questions, like the comparative costs of air vs. ground refueling or the comparative systems cost of primary basing in the ZI as against closer zones, bracketing solutions of the small or local problems will frequently suffice: (e.g., if we can fix the upper limits of refueling base vulnerability and defense costs in the Soviet medium bomber zone, it appears we can reach a conclusion on some policy issues in the large). On the other hand, by taking some of the macroscopic conditions as fixed and working more closely with some of the local problems, manageable solutions there are possible too. In the latter case, greater precision is both possible and required.
It is a familiar experience in logistics research that starting with almost any point of departure one thing leads to another and this, after following a number of bypaths, fans out into still others, and these to others further inside the maze and, after a while, it is not very hard to get lost. The base problem does not differ from other logistics research problems in this respect. None the less, looking at the base problem temperately in the light of our survey, it seems quite possible to come upon a reasonable period with fruitful conclusions. Andre Gide's version of the story of the Labyrinth and the Minotaur is suggestive here. It seems that the reason people got lost in the Labyrinth and never returned was that they did not want to get out. The passages were full of fascination and heady odors; the food was excellent and the monster itself was beautiful. What helped the protagonist there, was not so much a piece of thread as a strict forbearance as to the enjoyments proffered; and another thing that broke the spell at a critical point was his realization that the monster was quite witless. We have a feeling that there may be some analogies here. Some of the differences on which base determinations might be founded are very gross. Or so it appears from this first overview. If this is true, with a little forbearance in the bypaths, recommendations might emerge after a rather short list of detours.
-  When General Maddux describes his paper on "Air Base Considerations Affecting an Expanding Air Force" as considering "the problem from a purely military point of view not restricted by considerations of cost" and goes on to suggest that "cost be introduced as a factor later in the planning when the effect can be seen more clearly," he has in mind postponing the consideration of costs of installation elements, and this until they can be matched with considerations of effectiveness. The burden of this part of his statement is actually much the same, therefore, as our apparently contradictory emphasis on costs. We stress the total systems cost.
-  In fact, since the peacetime life expectancy of a runway considerably exceeds that of an aircraft, comparing the initial costs of these items without considering this fact tends to understate the cheapness of a runway in relation to an aircraft. See D-1062, "Initial and Annual Costs and peacetime Life Expectancies." In our analyses of the base problem we have followed the practice of amortizing base installations in ten years as well as the customary RAND procedure which amounts to amortizing them in four.
-  1,080 sq. ft. houses, as we recall, cost about $50,000 apiece at the time of the Inquiry.
-  Air University Thesis. Ground Support of Fighter Operations in Arctic Regions at -65 degrees, N. G. Morris, Nov. 1948.
-  Most of the material concerning the critical points of negotiation in obtaining base rights and on the political problems raised by the actual operation of bases was obtained from members of the Office of the Assistant for Bases in the Air Force: in particular, General Maddux, Colonel Crystal, Colonel Clinkscales, Colonel Coddington, and from various members of the State Department, in particular, Miss L. Leighton.
-  Town and Country Planning, 1943-1951. Command 8204, April 1951, pp. 81-98.
-  There are, however, some direct logical connections between extreme or pure versions of both views. See Section 7 - c.
-  "Must We Shoot From the Hip?"
-  We have also included two hypothetical Soviet air bases in the Lena River area and the Chukotski Peninsula in the extreme northeast parts of Russia. They are assumed prior to examination of intelligence data in order to indicate some target locations against which our Arctic bases might have an advantage. They appear to be likely locations for some Russian long-range bomber bases, and they differ markedly from any of the industrial target groups against which our Arctic bases appear to be inferior.
 The measurements have been made on a rather small globe and the resulting scale is very coarse. At this stage of the analysis in which our major interest is survey and illustration rather than firm base selection, only very gross differences are relevant, and these measures appear quite adequate.
In order to simplify base-target computation, twelve target areas were chosen, and within each target area the centroid located (each target assumed of equal weight). The base-to-target centroid distance was then used in the determination of length of missions and sortie rates. The use of target areas and their centroids introduced certain errors of approximation. Two of these have effect on the accuracy of sortie costs against targets in any chosen area. First, base-to-centroid distance is not exactly equal to the average base-to-target distance within each target area. Second, the use of the centroid in determining sortie costs against all targets within an area is in error when some of the targets in the area require one more refueling than others in the area. The areas were chosen so that these errors combined are less than a maximum three per cent. A different grouping of targets would result in slightly different errors of approximation for base-centroid distances and for the effect of additional refuelings within an area.
A third possible bias might be introduced in the grouping of targets itself. Selecting groupings in such a way as to increase the number of groups in which, for some bases, refueling breaks occur, might conceal some target sets (to be selected in another way) for which these bases have maximum advantage. This has been checked also and found to be of minor importance.
So far as base-to-target distances are concerned then, errors of measurement do not appear to be significant. The problems of measuring penetration however are greater, since the total penetration distance is much smaller than the combat radius. The errors analyzed above may be large in relation to penetration distance.
-  R-171. Bomber Capabilities, 1954 Turboprop and Turbojet Powerplants.
-  "Some Effects of Combat Radius." RM-599, Figure 4.
-  Air Ministry, CS-113741, Sept. 1943, "Air Attacks on Airfields."
-  See RM-730, "Time Equipment and Costs to Repair Cratered Runways," J. J. O'Sullivan.
-  Since bombers in the air are relatively invulnerable to attack by other bombers, it appears that one of the best ways to defend aircraft on the ground is to get them into the air when there is a report of attacking aircraft. Those planes which cannot be made airborne could be towed to revetments or dispersed. The amount of warning of impending attack depends on the location, and the coverage of the radar net and probably varies widely for overseas locations. The ZI offers one unique advantage from this standpoint. That is the amount of warning that is provided by the radar net. The expected warning time provided by the programmed radar net ranges from approximately one-half hour to six hours for attacks by TU-4's. Of the 38 heavy and medium bomb wings shown scheduled for permanent station in the ZI in January 1955, 19 of them are within 200 miles of the coast. Low level attacks by TU-4's or by submarine launched missiles would mean that these bases would get about one-half hour warning. Of these wings, four are to be assigned to the extreme Northeast and Northwest. (USAF Planning Budgeting Program, BPE-53-2, Conversion & Equipping Chart, Nov. 1951.)
-  Prepared with the assistance of Annette Weifanbach.
-  The B-47 assumed may be regarded as an optimistic B-47B with a radius of 2,000 nautical miles rather than the actual 1,750 nautical miles. The B-47C with a possible radius of 2,160 nautical is not now scheduled for procurement; the B-52 combat radius assumed is 3,000 nautical miles.
-  This is a little more than the 1,410 nautical mile weighted average distance for an overseas base complex in which targets are assigned to bases on the criterion of proximity rather than cost as in Section 6.
-  See Section 7.
-  R. Schairer has mentioned that there is some question as to the relationship between R-171 and the more optimistic capabilities assumed in the Intercontinental Bombing Systems Analysis. The time reference of R-171 is now obscure. It was prepared in 1950 as a prediction of capabilities in 1954, provided the recommended developments were started in 1950. Starting in 1952 it is clear that the four-year development cannot be telescoped into two. On the other hand, presumably, the state of the arts has developed some since 1950, despite the failure to follow RAND's recommendations. Is 1955 or 1956 the right year?
-  CF D-1068, "Logistics Research," David Novick.
We wish to thank Marc Peter and J. J. O'Sullivan for their Contribution on vase vulnerability, and members of the Cost Analysis Section, Aircraft, Missiles and Electronics Divisions for their suggestions and stimulating discussion of much of the material presented in this paper.