The chosen instrument at first was the giant B-36, with its six pistonengines and four jet engines. Its design was set by the desire for a 10,000 milerange with 10,000 pounds of bombs, so that it could reach any significant globaltarget and return to an American base. After some design difficulties weresolved, the intercontinental B-36 exceeded expectations and was in practical useby 1949, thanks to the hybrid addition of more power through its jet engines.
There were two means other than the intercontinental bomber for the Air Force toreach a target in the enemy's homeland. One was to use overseas bases for itsaircraft, and some were regained when Western Europe became frightened aboutRussian intentions. The second way was to use aerial refueling. The Air Forcehad experimented with the idea between the wars, but the attempts were crude.After the war, the British developed the probe-and-drogue system, which used aflexible hose, and the Americans adopted it and used it for smaller aircraft.The Americans developed the flying-boom method, which transfers large quantitiesof fuel quickly, for large aircraft. Two schools of thought emerged in the AirForce on the fonn the aerial tanker would take. One believed in using atransport aircraft to double as a tanker; the other preferred to convert bombersas both more efficient, because of the ability to use the same plane as abomber, and cheaper. The transport advocates won.
The adoption of aerial refueling was a key development. It greatly expanded theaerospace business from 1951 on, for it added a whole new class of airplaneswhose numbers would run around two-thirds of the bomber force, plus tankers fortactical airpower. The tankers proved useful in enabling aircraft to reachtargets, and in ferrying aircraft, -but the tanker was always regarded as anexpedient, and the ideal solution for combat was thought to be the big bomberwith requisite range.
Tankers speeded the development of jet bombers, for they circumvented theproblem of high fuel consumption, which was a limitation of the early jetengines. And the Air Force wanted jet bombers badly because jet fighters haddone well against the relatively slow piston bombers of World War II. Also,bomber men believed the jet bomber would be invulnerable to the fighter. If thebomber flew just below the speed of sound, the time available to intercept wouldbe greatly reduced; and if the fighter did catch the bomber, it would be forcedto maneuver and I fire its guns while going back and forth between subsonic andsupersonic conditions. The bomber people hoped this would present insolubleproblems to the fighter.
Work on the XB-47 medium bomber had begun in the autumn of 1943. Initialinvestigations were done on four configurations, two jet andtwo propjet. The design first chosen resembled the B-29, with four jets in twowing nacelles. In an attempt to reduce nacelle drag, the four jet engines weremoved into the body; side intakes were provided, and exhaust was discharged fromthe top of the straight wing's center section.This second design, which resembled a Hying boat, was firm by December 1944.When knowledge of the German swept wing was received, a new version of the XB-47incorporating the development was started. It was finished by September 1945.The four jet engines had been moved forward, to use nose intakes; exhaust wasover the top of the wing; and two additional jet engines were added at the tail.This design was again changed to incorporate the German idea of engine podsunder the wings:four of the engines were put into two pods, and two were mounted on the wingtips. The last change was to move the two outboard engines from the tips andsuspend them in pods like the other engines. In December 1947 the XB-47 as weknow it was Hying, and Boeing engineers knew they had a winner, claiming that itwas as revolutionary a design as the B-17 had been.
The design history of the XB-52 heavy bomber is linked to that of the XB-47because of the incorporation of development experience. It began in April 1945, when the AAF asked for a long-range,. turbine bomberdesign. The first Boeing configuration was ready for a June 1946 designcompetition. It won. This first model resembled the B-36, with six propjetengines, and it was expected to weigh 350,000 to 400,000 pounds. Rangeprojections of this model were unsatisfactory, however.When Wright thought that they could produce a more powerful engine, the designwas shrunk in late 1946 to a four-propjet version, but it still was short onrange and speed. To get better performance, aerial refueling was accepted asnecessary, and in early 1948 the wings were swept gently and contrarotatingpropellers were used. By the summer, propjet engine development for the XB-52was in trouble, and prospects for the power plant to be ready in less than fouryears were dim. Wright Field proposed conversion to jet engines. Boeing'ssolution, resulting in part from the success of their B-47, was to use eight jetengines in four pods and to increase wing sweep; and the XB-52 evolved into ascaled-up B-47.
Boeing's B-17 had established the form of the large four-engine piston airplane,and Boeing engineers had now spent eight intensive years on the design anddevelopment of big turbine aircraft. Almost every conceivable turbine enginecombination and mounting had been tried, and every style of non delta wing hadbeen examined. The design possibilities were manifold, but in the end Boeingknew they had found an effectivecombination for the big airframe. It has served them for a quarter of a centuryin the B-47, B-52, 707, 720, 727, 737, and 747 families and has been generallyadopted throughout the world.
As the Boeing jet bombers neared operational service, the Korean Wardemonstrated that jet bombers were not just an idealistic improvement: they hadbecome necessary for bombardment aviation. The MiG15's superb performancedestroyed the American illusion of Russian technical inferiority. Designed todestroy a possible successor to B-29's, it was able to slaughter the B-29. TheSuperfortress, still used in quantity by the Strategic Air Command, fled to thecover of darkness in 1951.What was even more shocking, the MiG's were masters of the jet RB-45, which thebomber enthusiasts had expected to be practically invulnerable against anyfighter. The RB-45, as well as the B-29, had to be withdrawn from daylightoperations. Faced with the prospect of future improved enemy fighters, fourteenof the B-36's guns were removed and other weight eliminated so it could operateat 50,000 feet and above, to redress the odds. When the B-47 jet bombers finallybecame operational in 1951 their speed, as had been hoped, was a problem to thefighters.
The bomber was soon in difficulty again, however, as technology advanced. Withjet-thrust augmentation, or afterburning, faster climb rates and supersoniclevel flight to over Mach 2 were attained. Themissile, with conventional or nuclear warhead and terminal guidance, wasdeveloped for use by the fighter, and weapon aiming was made simpler byavionics. By the midfifties the fighter had once more attained a markedsuperiority over the bomber, and the development of excellent antiaircraftmissiles at the same time compounded the bomber's problem.
Vigorous efforts were made to restore the bomber's viability. The Strategic AirCommand had long planned to use fighter escort systems, but the extreme range ofSoviet targets made traditional escorts difficult even with aerial refueling. Anattempt was made to adopt the B-36 into a flying aircraft carrier to solve thisproblem, while fighters were modified to be carried in the bomb bays or on thewing tips. Some fighters were to do the bombing, thus creating a stand-offbombing system for the B-36. The B-58 of 1957 and the XB-70 were developed togive the bomber supersonic speeds to limit the fighter's advantage, but the B-58had only a supersonic dash, and that was at high altitudes. The XB- 70 hadcontinuous supersonic flight, but the speed generated enough heat to make thebomber a dream target for missiles using heat-seeking guidance, and it was easyfor radar to find. McNamara called it a strategic dinosaur. For years intensiveefforts to provide the bomber with an air-to-air missile defense againstfighters failed technologically.
In the end the only practical courses of action were development of stand-offair-to-ground missiles, such as Hound Dog and Skybolt, to be used againstsurface air-defense installations as the bomber flew towardsthe target; use of electronic countermeasures (ECM); and flying just above theground so as to hide from radar. New models, the 1959 B-52G and 1961 H, had tobe developed for the low-altitude tactic.
The heavy losses to be expected from grand-strategic operations against acompetent enemy, with the highest loss estimates at a rate of 75 percent to 90percent, reduced the bomber in the sixties to an auxiliary weapon. Thebomber-oriented Air Force refused to accept this as a permanent condition, andrenewed development proposals for heavybombers followed each defeat of an earlier attempt, until the B-1 project wassuccessfully implemented in 1970. The Air Force even, in desperation, sought toreopen assembly lines for the B-47, B-52, and B-58. A measure of the intensityof the desire for more manned bombers is shown by the B-58's inclusion in thislist, for its production was ended early, in 1962, because of Air Force distastefor such a small bomber.
The twilight of both heavy and medium bombers as well as the auxiliary tankers,which started in the late fifties, resulted in the loss of a major market to theaerospace industry. This was the first large sales loss to the industry as awhole, and it was of special importance to Boeing, which had dominated bothstrategic and tanker markets. Boeing was able to partially offset the steepdecline in its sales to the government by having the foresight to take over theAir Force strategic-missile business with the Minuteman.
General of the Air Force H. H. Arnold accurately predicted in 1945 that themissile would displace the grand-strategic bomber. His vision, together with aresolve that American aeronautical inferiority should not be repeated, led tothe creation of two agencies to advise the AAF on directions to take in researchand development (R&D). One was RAND (Research and Development Corporation),which soon proposed an earth-satellite project. The AAF did not follow thisadvice, but it did accept that of the other agency, the Scientific AdvisoryGroup, led by Dr.Theodore von Karman. This second advisory group made proposals intended toestablish a foundation for future development. One was to emulate the Germanorganization for research and development, wherein all technical disciplinespertinent to a project had been brought together into a unit. Today this iscalled a "systems" approach. Other recommendations emphasized air supremacy inthe near future and downgraded advanced missiles. It is ironic that, to avoidrepetition of the earlier technological lag caused by short-term development,the group appointed to advise the Air Force was now recommending a similarshortterm approach. RAND, whose advice was initially rejected, did better.
Nevertheless, some work did begin on intercontinental guided missiles althoughthe emphasis was on two unmanned aircraft, successors to the German V-I: theNorthrop Snark and the North American Navaho. The Snark was to be jet poweredand subsonic, the Navaho to be ramjet powered and supersonic. There were yearsof struggle and failures with the Snark. The missile ultimately becameoperational only at squadron strength because it was vulnerable. The Mach 3Navaho also went through years of difficulties and was successfully fired onlyafter it had been canceled in 1957. Two other unmanned aircraft were developed,the Fairchild Goose, intended to divert air defenses from bombers, and theBoeing Bomarc interceptor. The Goose was canceled for the same reasons as theSnark and Navaho: too vulnerable. Bomarc alone became operational insignificant, although small, numbers. Curiously, production was continued atthis time on the big subsonic manned bombers, which were twenty times asexpensive and not much less vulnerable-an inconsistency which can only beexplained by a "battleship general" outlook: dogged clinging to a weapon foritself.
The unmanned aircraft, a guided missile, was for years believed to be easier todevelop than the ballistic missile, and it was expected to be a bridge to thelatter. As it turned out, the ballistic missile was less difficult to achievethan the unmanned intercontinental aircraft because the guidance was easier. Butthe technological relationships, the aerodynamics, were linked as if development were to progress from jet aircraft tounmanned aircraft, then to missile.
Work on the ballistic missile began early. The V-2 and the atomic bomb inspireda contract between the AAF and Convair in April 1946 for Project MX-774,ancestor of the Atlas ICBM. The work did not enjoy a high priority because theexpected accuracy, together with the yield and weight of the atomic weapon,appeared to render the missile impractical. In June 1947 MX-774 was canceled,yielding to more immediate SAC concerns during an economy drive. To put MX-774into perspective as a program, about $465 million were spent for all researchand development purposes in fiscal years 1946 through 1948, but only $2.25million had been devoted to MX-774. In one of those fortunate cases of vision,Convair continued limited work on the ICBM with its own funds.When the dry hydrogen bomb was achieved in 1953, the yield-weight-accuracycombination changed to favor the ICBM. It assumed top priority in 1954as knowledge of its feasibility and Russian development efforts combined todictate urgency. To assure success, not only was General Dynamics' Atlas put indevelopment but a competitor, the Martin Titan, was sponsored as well. Asconcern deepened over Russian progress, especially after Khrushchev "rattled hisrockets" during the 1956 Suez crisis, it was realized that an IRBM could be madeoperational earlier because its shorter range meant simpler solutions. The AirForce produced its Thor in the late fifties in competition with the Army'sJupiter. Before these liquid-fueled missiles were successful, a solid fuelengine practical for big rockets was developed. Boeing realized this early and,concerned over future prospects for its bombers, worked hard in 1958 to win theAir Force solid-fuel ICBM competition.
Successful development of the ICBM and IRBM came during thecrisis of the bombers, and the missiles assumed the main aerospace-nuclearstrategic role. Cheaper than bombers, they were invulnerable after launch. Theyhad relatively short production runs, but productiondid not end when the missile silos were fined, for improvements caned forreplacements. In addition, the ICBM and IRBM were useful as boosters for thespace program.
Kennedy's conventional-warfare emphasis put TAC on an assured footing, althoughit has not become much larger. For the aerospace industry, TAC's story has meantthat the jet fighter business has been good in war but poor in peace. Fightershave continued to be cyclical; no company has done wen with USAF fighters forthe whole period, 1945 to 1972, and the one company that specialized in AirForce fighters, Republic, failed. Yet, unlike the bomber, the fighter stillappears to have a future with the Air Force and for export. And the fighter,along with the transport, is one of the best possibilities for the long serialproduction that spells profits. Fairchild had good business with the C-119 fortacticalairlift, but that business was lost to the C-130. Then Lockheed had a largemarket in supplying transports for our Air Force and for exports.The 1949 piston C-119 never had the usefulness and reliability of the 1954propjet C-130, a design which was still in production two decades later.For over a quarter of a century the workhorse jet engine created a continuingmarket for its services in tactical airpower.
The air-defense market, on the other hand, proved temporary. Before there was adiscernible Russian air threat the Air Defense Command (ADC) was formed. Lackingresources of consequence it was virtually a phantom command, resting primarilyupon the concept of big-bomber primacy, which in turn bestowed some status onthe counterweapon.Emergence of a Russian air-nuclear capability in the early fifties, followed bythe USAF miscalculation that the Soviet Air Force was building a massivegrand-strategic bombing force, caused a mushrooming growth of ADC in themidfifties. Growth stopped with successful development of the ICBM, and with theeventual realization in the late fifties that Russia was emphasizinggrand-strategic missiles and not bombers, as had been believed. It appears theAmerican miscalculation and redirection was a mixture of being hoodwinked by theRussians, the self-deception of top Air Force generals in imputing their ownintentions to others, and a change in plans as technology solved the feasibilityproblems of the ICBM.
The Russians did build a small force of 840 jet bombers, and together withnuclear weapons it remains a threat to the continental United States. Althoughthe mechanics of air-defense demand almost as great a force to combat a smallbomber fleet as a large one, it has been possible to reduce the U.S. interceptorforce from its peak. The stable nature of the Soviet bomber force means that theexisting interceptor force will continue to be serviceable. Thus, although theinterceptor market rose rapidly in the fifties, it has been almost nonexistentsince. The emergence of the ICBM as the main threat has not provided a marketfor an antiballistic missile (ABM), however. The technological problems of theABM have not been simplified, its costs have been appalling, and the hypothesishas been generally accepted that defenselessness will preserve the balance ofterror and, therefore, peace.
The third command, the Military Airlift Command (MAC), has, like the TacticalAir Command, grown in recognition. MAC performs strategic -that is,international or global-airlift functions, hauling large payloads for longdistances in short times. As with commercial air transport, the power-to-weightefficiency of the jet engine has made strategic airlift increasingly effectiveand important. Repeated attempts to achieve thatgoal with piston engines met with moderate success. Of the giants that werebuilt in this effort at the end of World War II, the Douglas C-74 Globemaster I,Lockheed R60 Constitution, and Convair XC-99, derived from the B-36, wereunsuccessful. The Douglas C-I24 Globemaster II of 1949, informally called "TheAluminum Cloud" and "The Flying Reynolds-Wrap," and the semigiant Boeing C-97Stratofreighter of the end of World War II were the best of the large pistontransports. Propjet efforts were made with the canceled Douglas C-132 and the1957 C-133 Cargomaster. Progress towards jets and modern aircraft was not asfast as the Military Air Command wanted and technology permitted. The commandhad no jet transport until ten years after jet bombers were in service, and in1963 the piston transport was still the backbone of the fleet. One of therationalizations put forth by the bomber generals, a claim which sounds strangecoming from the Air Force, was that speed was unimportant in a transport. Thisidea -was not shared by those in the transport business: the airlines and theairlift command.
The C-133 was followed by a major step: the C-130 Hercules concept was enlargedand equipped with jet engines, and the result was a greatly improved strategictransport: the 1964 Lockheed C-141 StarLifter. Its success encouraged beliefthat the ultimate size could be achieved. The Lockheed C-5A Galaxy, also called"The Aluminum Overcast" or "Fat Albert," was built next; and the apparentcommercial success of the C-5A's airliner counterparts-the Boeing 747, LockheedL-I011 TriStar, and McDonnell DC-IO-indicates that the jet engine has made thegiant air transport, and therefore large-scale strategic airlift, feasible.General Arnold, in 1945, not only prophesied the ICBM, he also forecast an aircapability to deliver ground forces, completely equipped, at any point in theworld within hours. Such strategic airlift should have as bright a future as itscommercial counterpart, and be an additional continuing market for the aerospaceindustry.
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