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Chapter 3: The Call for Equipment (January–May 1942)

Supply Dominating Research

Certainly the mustering of men in response to the call of declared warfare was the most pressing demand. But business-as-usual had restricted the amassing of equipment also. The lag had continued up to and right through the opening of belligerency—automobiles, for example, still coming off production lines; and only now were signs beginning to appear that the supply branches of the armed forces could count on access to industrial production facilities and stockpiles of material. Fortunately, during the months before Pearl Harbor both the activity and the outlook of the Signal Corps had sufficiently expanded so that, with the long period of waiting at an end, the men responsible for equipping the Army with signal machinery knew their problems better. They knew that they would have to meet daily demands bigger than many past yearly ones. There was too little in the field, or in the course of production, or under development.

The problem indeed seemed to be that to reach the field with signal equipment they would have to devise the sets and manufacture them almost simultaneously. Manufacture was a problem not chiefly theirs but American industry’s. Development, too, they understood to be in large part shared. The achievement of mobile radiotelephony and, above all, of radar had demonstrated the limitations, along with the triumphs, of military laboratories and had made it plain once again that Signal Corps research would be almost as closely attached to civilian partnership as Signal Corps production would be. Signal Corps research and development activity would cooperate with civilian laboratories under the government, like the newly constituted Radiation Laboratory under the Office of Scientific Research and Development, and would also rely heavily upon the laboratories of large producers, like Bell or Westinghouse. Pressure upon research would be a pressure toward supply.

That supply dominated research was borne out by reorganizations, first within the Signal Corps, and then within the War Department itself. In August 1941 one of General Olmstead’s first acts as Chief Signal Officer had been to transfer Col. Roger B. Colton from the Monmouth laboratories to the Washington headquarters. Here he had put Colton in charge of a newly created Materiel Branch. Under Materiel, the formerly separate divisions of Supply and of Research and Development became a team. After war came, there was never any doubt

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as to which teammate dominated. It was supply. And Colton, primarily a research and development officer, had to devote the bulk of his efforts to procurement problems.1

This shift of emphasis appeared in the March 1942 reorganization, when three major commands emerged within the Military Establishment of the United States. Under one of the three and its commander, Lt. Gen. Brehon B. Somervell, all the technical and most of the administrative services were caught up in a single net and ticketed Services of Supply (SOS). The name tended to tag the Signal Corps, from then on, as a supply agency. Its duties as an arm, as an arbiter of communications, and as a research agency, suffered by comparison.

Olmstead realized what the effects of the reorganization would be when he first saw a copy of its chart. “I went down to the Deputy Chief of Staff, General [Maj. Gen. Richard C.] Moore, at that time,” Olmstead related to a board investigating communications in May 1943, “and I said, ‘The set-up is wrong in so far as Signal is concerned. For supply, yes, it is O.K.; but there are many, many things that the Chief Signal Officer has to do that affects the over-all communications of all concerned,’ and I said,” Olmstead concluded, “ ‘Every man is entitled to his day in court.’ ” General Moore’s comment left no room for discussion. As Olmstead related his response, Moore flatly replied, “You won’t have any day in court. This organization has been decided upon. Those are orders.” But at a subsequent staff meeting in the SOS, General Somervell admitted the difficulties which the new organization created and said, as Olmstead recalled his words, “Well, let’s try this thing out, and if it doesn’t work, adjustments will be made.”2

As an agent for procuring, distributing, and servicing equipment, the Signal Corps was appropriately gathered in with the other supply and service agencies of the Army under Somervell. In these tasks, its work continued to progress no less well at the new organizational level than before, when the Chief Signal Officer had stood one step higher in the Army’s hierarchy.

But in his many other duties, especially in matters of communications policy, coordination, and control, the Chief Signal Officer’s voice was muffled under the blanket spread between him and other Army agencies, and this at the very time when the unique and multifarious significance of electronics in warfare was beginning to obtain recognition. The Secretary of War, Henry L. Stimson, commented early in 1942, “I had been under the misconception that most have been under as to the importance of Signal Corps work in this war ...; it has suddenly leaped to the forefront of interest.” He went on to observe that perhaps other branches had “rather high-hatted” the Signal Corps, thinking of it as a lot of men who “just made flags,” rather than realizing that “the Signal Corps is now the focus of applications to war of a new science.”3

Stimson’s misconception and enlightenment did not relieve the Signal Corps from its lowered status. The March 1942 reorganization, which had dropped the Signal Corps to a lower level than it had formerly

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enjoyed, had done the same for all the technical services. It had also stepped down the Infantry, the Armored Force, and other Army components which the Corps was accustomed to serve. It left the Signal Corps’ largest single customer, the Army Air Forces, one level higher. Figuratively speaking, when Olmstead talked to Arnold, the line would have to carry the voice of Somervell as well as his own. Moreover, the circuit to most signal officers in the field was broken; that to the Chief of Staff was blocked. Without a direct line to the Air or Ground Forces, or to the Staff, or to the corps areas, the Signal Corps was obliged to ask the Services of Supply to do its talking, expressing even the most technical sentiments to them.4

Yet if the organization of the Services of Supply seemed to pull together dissimilar functions, not all of which involved supply, it only repeated on a large scale what Signal Corps administrative changes had already been doing, and were continuing to do. For the Signal Corps, like Somervell’s larger aggregation of services, was something of a hasty pudding whose ingredients tended to separate. General Olmstead was touring the west when the 9 March reorganization took place.5 But he immediately had his office reflect the change by creating new supervisory levels and inserting them between the chief and the divisions just as the Services of Supply and the Army Ground Forces now stood between the Chief of Staff and the arms and services.

Brig. Gens. James A. Code, Jr., Roger B. Colton, and Charles M. Milliken now were designated respectively Deputy Chief Signal Officer, chief of the Supply Service, and chief of the Field Service. These two services, Supply and Field, were the new supervisory echelons. Under Milliken fell the coordination of communications and air communications as well as personnel and training, together with signal plans and operations. Code remained the principal administrative officer. For a time photography was removed from Army communications, where it had not fitted at all, and was attached to the Administrative Branch, where it fitted no better. Its divergence was immediately apparent, and so was that of the administrative communications complex; so that there was nothing to do but to raise each of them to the level of services also.6 Simplicity of organization seemed unobtainable. Unrelated functions, boxed together in an organization chart, were not any more securely packaged in one than in another, whether in the Office of the Chief Signal Officer’s box or in the Services of Supply’s. They kept bursting the lid.

Meanwhile, a lesser move organized General Olmstead’s executive staff into two directorates, Col. Frank C. Meade heading one for planning, Maj. William D. Hamlin continuing the executive function under a new title. The fact that Lt. Cols. Francis H. Lanahan, Jr., Victor A. Conrad, and Wesley T. Guest were all assigned to Meade suggested that the Directorate of Planning was to have considerable importance. All the while, after 9 March, the presence of the Services of Supply was making itself felt, so that planning in any echelon below it was likely to be reduced to either

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following prescriptions from above or unobtrusively seeking to write the prescription.

These many changes in organization were made in an effort to keep up with an expansion so swift that even under a system with which they were familiar, administrators would have been strained to coordinate and supervise so many new units. The over-all Services of Supply was not familiar, but new, disparate, and untried. It added to paper work. Some of its directives were wholly extraneous. Some followed procedures already in effect but with just enough deviation to make reissues of Signal Corps directives necessary in order to conform.7 Regulations became increasingly verbose. How properly to prepare letters, memoranda, and routing slips plagued the thousands who either dictated or typed them. Confusion of this sort penetrated to all levels of command. The Chief Signal Officer encountered it in dealing with his superiors in the Services of Supply and with his subordinates in the Signal Corps.8 Yet somehow, in spite of annoyances, obstacles, devious channels, regulations, and directives, in spite of organizations which fell out and re-formed almost daily, the heterogeneous and hastily assembled office staffs and all the phases of Signal Corps activity in the critical early months of 1942 gathered momentum. Even Research and Development, however roughly shouldered by its running mate, Supply, continued to cover ground fast.

Colonel Colton had come to Washington from the Signal Corps Laboratories to become chief of the Materiel Branch, now the Supply Service. Colton was in many respects the number two man in the Signal Corps, and as director of the Fort Monmouth laboratories had been at the forefront in the research and development organization. He was a man whose background included degrees in electrical engineering from Yale and the Massachusetts Institute of Technology. In its eighty years the Signal Corps had built up a tradition of technical men who were well able to deal with scientists on scientists’ terms. Col. Hugh Mitchell, Colton’s chief subordinate as head of the Research and Development Division, had long been associated with Signal Corps research, as had Lt. Col. Tom C. Rives, Mitchell’s deputy. Both had M. S. degrees in electrical engineering from Yale, and Rives had been so long and so closely a part of the Signal Corps development work for the Air Corps at Wright Field that he knew the subject well. These were experienced research and development officers, as was also Colton’s successor over the Signal Corps Laboratories, Maj. Rex Van Den Corput, Jr., not to mention Col. John H. Gardner, director of the Aircraft Radio Laboratory serving the Air Forces at Wright Field, Ohio.

At the Washington headquarters, Colton was demonstrating a feat of Roman riding. Of his two steeds, the one, Research and Development, which had been galloping hard upon Pearl Harbor, was being pulled short by the other, which was Supply. For the Supply mission, so much more the communications industry’s creature than the Signal Corps’, had scarcely begun to lengthen its pace. From now on, Supply demanded and got most of Colton’s

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attention because shortages of almost all categories of equipment were critical throughout the Army.9 The dual organization under Colton was based upon the “premise that Signal Corps supply begins with Research and Development.”10 On this premise a Radar Division made its appearance in January, because radar supply was the object of one of early 1942’s most desperate calls. The demand for radar was universal; it came even from Secretary Stimson, who was highly alert to radar’s capacities.11 In a move which reached through the Office of the Chief Signal Officer to the Laboratories themselves, radar work was set apart from general development.

In the Fort Monmouth area what became known as radar was called Radio Position Finding. The RPF Section of the Signal Corps Laboratories became Field Laboratory No. 3, isolated for secret work, apart from the eyes of the curious, in the scrub barrens of Sandy Hook, New Jersey. Work on ground radar had already expanded into areas in Rumson, New Jersey, near the Hook; at Twin Lights, Highlands, New Jersey, at the very base of the Hook; and on Sandy Hook itself, site of Fort Hancock, then a Coast Artillery installation guarding the approaches to New York Harbor.12

Radar was the electronics prodigy, and in considerable part a creation which the Signal Corps had attended from the beginning. It had grown so rapidly (however secretly) that it had ceased to be merely a specialized field of radio.13 Formally, the Signal Corps radars were still SCR’s, but actually they had moved into another area of electrical communication altogether. It is worth quoting personnel figures to show the extraordinary advance of the new equipment in the total range of the Signal Corps’ research and development interests. At the end of the fiscal year in June 1942, 62 percent of the officers assigned to research and development and 55 percent of the civilians were concerned wholly with radar or with the related work on aircraft communication and navigation equipment. The growth of the research and development function as a whole appears in the fact that 358 officers and 14,337 civilians were at work in the Laboratories and in Washington six months

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after Pearl Harbor, where six months before that event there had been respectively 63 and 1,619.14

Recognition of the fact that the emphasis was thus being redistributed brought about the January change in the Materiel Branch which made radar, with Colonel Rives at its head, a separate division. The assignment given the Radar Division was as explicit as it was total. It was to be “responsible for the supervision of all Radar and Aircraft Radio ... from the inception of the project until the equipment is developed, procured, installed, and [provided with] the proper spare parts and maintenance personnel. ...”15

At Wright Field a parallel change occurred, which brought radar into a separate unit supervised by Maj. William L. Bayer and merged the communications and navigation units into the single responsibility of Lt. Col. Hobart R. Yeager.16 In the fact that Yeager was an Air Forces officer was proof that the Air Corps and the Signal Corps could cooperate. Further proof lay in the careers of Bayer, enthusiastic for airborne radar, and of the director of the entire laboratory, Col. John H. Gardner, who had been at Aircraft Radio Laboratory long enough to feel the pride of possession about it.

At Fort Monmouth, meanwhile, as Field Laboratory No. 3 became the Signal Corps Radar Laboratory in January (soon transferring to Camp Evans, Belmar, New Jersey), ground radar became the entire concern of Lt. Col. Rex Corput, Jr., one of the men who had known it longest and most searchingly. The pattern which began to appear with emphasis upon radar, dividing research and development equally between radar and other kinds of equipment, was thus completed at Monmouth as at Dayton. Lt. Col. Oscar C. Maier was appointed chief both of Squier, at Monmouth, and of the two Field Laboratories, at Eatontown and Camp Coles for wire and radio respectively, and together given the name General Development Laboratories. Correspondingly, Lt. Col. James D. O’Connell, an officer who had an amount of experience at the Fort Monmouth laboratories comparable to Rives’ at Wright Field, became director of the parallel General Development Division in the Office of the Chief Signal Officer.17 Thus all of the fundamental and vital Signal Corps research in the long-established fields like wire, radio, and meteorology came under O’Connell’s supervision.

Wire, the Basic Equipment

Wire and wire signaling devices had long been the core of signal operational equipment and, in providing the bulk of communications for large Army installations in World War II, would remain so. A core of huge dimensions it would become, in direct proportion to the scale of vast, indeed world-wide, theater operations. Thanks to the application of the commercial carrier system to the military, a single wire circuit could carry not one but several signals simultaneously. Telegraph in particular would be entirely revolutionized, both in established administrative circuits and in temporary

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field installations, because of another recent commercial development, the teletypewriter.18

During 1942 teletypewriter equipment went into the field in a big way for the first time, and not a moment too soon to meet the needs of the many huge installations springing up throughout the zone of the interior. In March 1942 production of telegraph printer sets EE-97 and EE-98, for mobile and fixed operation respectively, began with the delivery of 150 sets in the first batch, somewhat ahead of schedule.19

The introduction of the teletypewriter into the Army required a new switchboard and suitable accessories, in fact a whole telegraph or teletypewriter central office set, which became the mobile TC-3. Under project 4-17 set up in the summer of 1940 the Signal Corps Laboratories had begun to develop the heart of the set, switchboard BD-100, a 10-line board, weighing only 200 pounds, which was phenomenally light for equipment of this kind. The BD-100 was but one quarter to one third the size of the nearest comparable equipment which the Bell Telephone Laboratories had offered to the Signal Corps. The reduction largely resulted from the neutral system of teletype operation which the Signal Corps preferred to the polarential. The BD-100 gave excellent service throughout the war as part of the TC-3, and constituted “one of the major contributions in the field of telegraph-and-teletype-switchboard design.”20 In the spring of 1941 the Signal Corps Board had given test models a thorough going over and then its blessing. By September the Signal Corps had completed procurement arrangements, and now in 1942 the Army began getting the new teletypewriter switchboards, while the Signal Corps General Development Laboratories at Eatontown completed the development of the TC—3. The complete set, including one TG-7, a rectifier, the heavy power unit PE-75, the switchboard itself, together with tools and spare parts, weighed about a half-ton.21

The immense traffic potential of teletype would mean little if the linking wire lines were inefficient, limited in capacity, easily injured or disrupted, slow to install on poles. This had been the situation in the 1941 maneuvers when Maj. Raymond C. Maude had reported that the limited range of field wire W-110-B restricted it to use within a division. What was wanted, he had said, was a field wire able to carry voice

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New developments in 
signal communications included spiral-four cable (left and right above) and the BD-100 teletypewriter switchboard 
(below), with three TG-7 teletypewriters

New developments in signal communications included spiral-four cable (left and right above) and the BD-100 teletypewriter switchboard (below), with three TG-7 teletypewriters.

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35 to 40 miles and capable of being installed quickly. Open wire construction involving pole lines was too slow, he added, to keep up with moving armies. The Eatontown Laboratory now had spiral-four, the answer to Maude’s wishes.22 It received its name from the arrangement of its four wire conductors, which spiralled around a fiber core. The whole, wrapped in wire shielding, then encased in an insulating rubber jacket, was devised to provide long-range carrying power with minimum electrical loss and cross talk. Flexible, half an inch in diameter, of a tensile strength over 600 pounds, yet not excessively heavy, it could be handled far more expeditiously than other cables that the Signal Corps had used before. The Signal Corps developed plastic snap connectors, so that crews unrolling the quarter-mile lengths (called cable assemblies, CC-358) from standard Signal Corps reels DR-5 (or adapted for spiral-four as DR-15) could quickly link one length onto another. Moreover, into each connector was built a loading coil and balancing condensers which extended the talking range to 40 miles, without the use of repeater equipment. In January 1942 the Signal Corps announced this new field cable, with high hopes for favorable reception. By the end of the month, on 26 January, the Signal Corps Technical Committee recommended its standardization and the War Department made it official on 18 February. Western Electric, General Cable Corporation, and U.S. Rubber each contracted for small quantities for service testing.23

The Signal Corps did not have the honor of devising spiral-four (WC-548). It had been adapted, through the British, from a German long-range field cable, some of which British commandos had seized in early raids upon the Continent. From it, the British had developed what they called quad cable. Signal Corps laboratory representatives had seen samples for the first time in the Bell Laboratories during the summer before Pearl Harbor. Perfected for American use by the Bell and Signal Corps Laboratories working together, spiral-four helped make possible military use of commercial carrier circuits and the extension of the heavy duty communications systems directly to the theaters of war.

By 1942 Signal Corps wire engineers had this field cable so well in hand that they had begun to develop carrier communication equipment for it. A C-type spiral-four carrier permitted four conductors, whether on poles or in a cable, to carry many telephone, telegraph, and teletypewriter circuits simultaneously. A single spiral-four field cable could do the work of multiple open wire lines and obviate the slow tedious preliminaries of setting poles, fixing crossarms, and stringing the individual wires. Spiral-four, laid on the ground or buried, also avoided the exposure to enemy action which a pole line invites. Under laboratory projects 2-4, entitled Field Cable Research, and 4-18, Carrier Telephone Systems, this work was now progressing. Field wire systems which in former days sufficed for distances of only a few miles and for the transmission of only occasional messages were going to be supplemented by systems which could relay messages for hundreds of miles, and not just occasional signals, either, but unbroken torrents of voice and teletype flowing night and day. This became communications in

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the fullest sense, and spiral-four cable helped to make it possible even in the field.24

As the laboratories developed spiral-four and looked into the application of carrier systems to the military, field arms fast came up with requests for the new development. The Air Force Combat Command, for example, was beset with a need for multiple communication channels, both in order to serve the far-flung multifarious business of air defense and in order to channel quickly large numbers of aircraft sighting reports into information centers and then to convey instructions dispatched to intercept airfields. Thus swamped with communication needs which dwarfed any previous military requirements for a field arm, the Combat Command drew up the following request in the days immediately after Pearl Harbor. Learning from a Signal Corps laboratory memorandum of 15 December that spiral-four field cable was practicable, the Air Forces at once asked for 2,100 miles of spiral-four; 36 sets of telephone and telegraph carrier terminal sets, each to handle 3 voice channels and 4 teletype circuits; 60 carrier repeaters; and 12 sets of telephone terminals, each to handle 4 voice channels.

In short, the Signal Corps was going to have to provide carrier equipment at the telephone and telegraph terminals of the spiral-four cable, also repeater stations along the cable line to amplify the signals on their way. This equipment would be needed to feed the several simultaneous signals into the cable, to boost them any distance, and then to filter them out at the other end in an orderly intelligible manner. This AAF requirement reached the Signal Corps in the first week of 1942.25

These requirements for military communications on a huge scale, backed up now by the realities of war, brought forth from the Signal Corps C-type carrier equipment. For some months under project 4—18, Carrier Telephone Systems, the Laboratories had been considering military applications of Western Electric’s types H and G telephone carrier systems. By mid-1941 the project got a shove from spiral-four developments and the promise of huge communication capacity which the new field cable held forth. At the end of October 1941, the Signal Corps Laboratories reported that spiral-four research had “brought forth preliminary plans for a comprehensive system of voice telephone, carrier telephone and carrier telegraph systems to span distances from 50 to 150 miles and up. The projected system,” the report continued, “will furnish four speech channels over a single cable, one of which may be utilized for the transmission of 4 to 6 channels of voice-frequency carrier telegraph.” This would soon become C-type carrier equipment, a modification by Bell Laboratories of existing commercial equipment adapted for military use.26

Thus, under pressure of Army needs, the Signal Corps in collaboration with Bell Telephone during early 1942 worked up specifications both for carrier telephone terminal equipment, which became CF-1 (part of TC-21), and for repeater sets, which became CF-3 (part of TC-23). By

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March arrangements had been made also for telegraph carrier terminal sets CF-2 (part of TC-22). The Signal Corps placed orders with Western Electric for two sets each of CF-1 and CF-2, and for six sets of the repeaters CF-3, all to work with spiral-four field cable. This equipment would give the Army such long-range heavy duty communications as it had never before enjoyed in the field.27

But the Army would have to wait a while, for Western Electric to build the sets, for these to receive service tests, and for full production to follow, if all went well. Meanwhile, the Signal Corps prepared specific figures on what would be required to meet the needs that the Air Force Combat Command had outlined in January 1942. General Olmstead had asked the Monmouth laboratories to make the estimate. He got the answer late in March from Colonel Maier, now the head of the Signal Corps General Development Laboratory. Accomplishment of what the AAF wanted would call for some extras—ringing equipment for telephone channels, gasoline engine-driven generators, storage batteries, and trucks with trailers to house and convey the equipment. The cost, Maier estimated, would run to two million dollars.28

Although telegraph in the form of teletype (both wire and radio) would carry far and away the bulk of World War II long distance communications, telephone would receive very heavy use, too, especially in headquarter installations. By 1942 the Signal Corps had either in production or under development big telephone switchboards and central office sets which would quite repair the need Colton had claimed two years earlier, after the 1940 maneuvers, to be most urgent—namely, new switchboards for heavy duty headquarters use.29 Late in 1941 TC-1 for army headquarters, a huge central office set built around the 100-line switchboard BD-80, had gone into production. So too had TC-2, designed for use in corps headquarters, employing the 60-line board BD-89. These sets were ponderous affairs weighing tons, and might include not one but several switchboards installed side by side as traffic needs might require. The Air Corps men, wanting a small set weighing less than the divisional TC-4 (BD-96), got it when the Signal Corps Laboratories’ Wire Section (Eatontown Laboratory) developed the TC-12 around the efficient 20-line BD-91 (even it weighed a walloping 300 pounds). In January 1942 an Air Corps unit at Selfridge Field, Michigan, and another unit at Mitchel Field, New York, completed service testing the set. In February both returned a unanimous report—approved. On 9 March Lt. Col. Francis J. Magee, head of the Equipment Coordination Division, recommended BD-91 for standardization.30

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Signal Corps Switchboard 

Signal Corps Switchboard BD-72

All of the Army headquarters telephone and teletypewriter equipment, spiral-four and carrier, was heavy, entirely unsuitable for fighting men to carry forward with them. For them, in order to keep sharp the fighting edge of wire communications, the Signal Corps provided field telegraph set TG-5 (a buzzer, battery, and key for sending dahdits), field telephone EE-8, battery-powered, and, later in 1942, sound-powered field telephone TP-3 (TS-10), conveniently unencumbered by any battery at all. The Signal Corps provided the portable switchboards BD-71 and 72, lightweight field wire W-l 10, the still lighter weight assault wire W-130, wire-reeling devices such as the one-man chest reel CE-11, holding a quarter of a mile of assault wire, or such as the two-man cradle RL-31, or axle RL-27 employed to pay out W-110 from reels DR-4 and DR-5.

For fighting men on foot in the field, light weight was a prime desideratum, along with as great efficiency as might be compatible therewith. Though quantities of these items were already flowing to the field troops in early 1942, the Eatontown Laboratory continued work altering and improving. This it did with Signal Corps wires particularly, ever trying to increase their talking range, their strength, and the efficiency of their insulation against moisture and against the abrasion of rough use. Poor splices in the manufactured product were giving trouble, and in January the laboratory reported that it was pressing the factories to reduce the number of splices and to strengthen the unavoidable ones. In February the laboratory workers were trying out a knitted covering for W-110 in place of the braid whose manufacture consumed too much time. They kept up a continual effort to find

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insulation substitutes, thiokol, vinylite, buna, and so on, to reduce the consumption of precious rubber.31

BD-89 was the new division headquarters board, replacing BD-14. In the regiments, switchboards BD-9 and 11, of World War I vintage, had been replaced by BD-71 and 72, and not very happily either. They were the portable boards, with six or 12 plugs, which the forward fighting troops lugged to front positions and which connected up the light assault wire, W-130, or field wire W-110-B, as infantrymen furtively laid it from chest reels (CE-11) or from hand-carried cradle RL-31 or from the same cradle hauled in a jeep. The chief trouble with the boards was their unnecessary weight, about 50 pounds for BD-71, over 70 pounds for BD-72. And though the most obvious fault, weight was not their only defect. They were at first built from salvaged parts. On 15 January 1942 Capt. R. Lutes of the 54th Coast Artillery, Camp Davis, North Carolina, turned in an unsatisfactory report on the line signal coil: the lead-out wire broke from handling shocks and the coil itself shorted because of poor insulation. When the complaint came to the Laboratories, Capt. Floyd A. Minks, charged with Field Laboratory No. 2 (Eatontown), replied that the failure surprised no one. The coils had been salvaged from old switchboard units EE-2-B which had long languished in depot stocks. BD-71 and 72 had been built as stopgap sets and money savers, from parts of old World War I switchboards BD-9 and 11. The Signal Corps, harassed by money shortages until the first bonanza year, fiscal year 1941, had had to conserve.32

The Army was burdened throughout the war with improvised regimental switchboards. The obvious need for better portable boards led the Signal Corps, in April 1942, to prepare new military characteristics. In June, however, the effort was quashed by the Services of Supply and General Somervell, who “directed that no development of a switchboard to replace switchboards BD-71 and BD-72 be undertaken since the man-hours and the materials required for subject development could be employed to greater advantage on more essential projects for which no substitute exists.”33 The unsatisfactorily heavy BD-71 and 72 had to serve, and even they were not at hand in sufficient quantity (nor telephone EE-8, either) when war came. The Army had to use stocks of old BD-9 and 11, as well as the World War I telephone set EE-5.34

Radio for Mobile Armies and for World Communication

In 1942 the illusion of pushbutton warfare appeared, in electronic communication

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at least, with the arrival of the “500” and “600” series of radio sets (one might also include Air Corps’ VHF command set, SCR-522, with its four pushbuttons). In tactical combat among highly mobile fighting machines, these pushbuttons marked the beginning of really facile communications, in the sense that Colonel O’Connell had long been insisting upon at the Signal Corps Laboratories, as when he frequently declared, in effect, “We’re all through with radio; hereafter we want communications.”35

What O’Connell meant, of course, was instantaneous radiotelephone or intelligible voice exchange, not radio in the long-established military sense of continuous wave telegraph—spelled out laboriously in Morse code, if not further bedeviled by conversion into a secret code or cipher, into which the sender must first convert the plain text, and out of which the receiver must recover intelligible phrases.

During the two years before 1942, most vociferous of the ground troops demanding better radio equipment had been the Armored Force, seeking desperately to ready for combat its two original divisions, the First and the Second. Before the end of 1940 the Armored Force Board and the Signal Corps had decided upon a series of radio types that would completely meet all Armored Force needs. The types were AF-I, II, III, and IV, of which the III and IV would be multichannel sets with crystal control, allowing instant tuning or selection of frequency channels. By the turn of 1940 Capt. Grant A. Williams had induced the Armored Force to embark upon FM radio, based on police equipment built by Fred Link. Immediately, vehicular frequency modulation so pleased the tank men that the Armored Force switched from amplitude modulation to frequency modulation for its short-range tank sets. By early 1941, therefore, the Signal Corps had ordered hundreds of Link radios, short-range frequency-modulated transmitters and receivers, as substitute and training sets, pending the time when the Bell Laboratories and Western Electric could perfect and produce standard AF-III’s, converting them from their amplitude-modulated prototypes into the frequency-modulated pushbutton crystal-controlled sets to be known as the 500 series.36

The Signal Corps had begun getting the frequency-modulated Link sets for the Armored Force before the end of 1941, not so soon as the frantic tank men wanted them but somewhat sooner than radios of the 500 series could be had. The Link stopgaps were the SCR-293 (transmitter and receiver) and the SCR-294 (receiver only), of which 1,200 of the former and 400 of the latter had been put on order early in 1941. With unwarranted optimism the contractors had expected to complete delivery by September. But production tarried as one difficulty arose after another respecting the frequency channels of the sets, the power sources, and so on. Despite pressure from the Deputy Chief of Staff and Signal Corps appeals for a high priority, no sets were delivered until October 1941. Thereafter production

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gradually increased to reach a total of nearly 700 sets, 554 SCR-294’s and 138 SCR-293’s, by the week ending 3 January 1942.37

Now, in January 1942, with the war on in earnest, the production of the 500 series by Western Electric had just barely begun and the deliveries of the Link stopgap sets were behind schedule. Desperately the Armored Force increased requirements for short-range FM’s, even including the substitute training Link sets, which were never intended for battle use. They would see combat just the same, since they were the first produced and since every last FM vehicular radio was needed on fields of battle.

By mid-January the Signal Corps had not yet completely equipped even the 1st and 2nd Armored Divisions with modern radio. Armored Force’s latest radio requirements, just drawn up by Lt. Col. William P. Withers, demanded over 2,500 sets for the 1st and 2nd Divisions—a mighty increase over 500 sets, the request for which had seemed so huge only a year and a half earlier.38 Moreover these 2,500 sets were all (except for 169 SCR-193’s and 6 SCR-299’s) the startlingly new and superior type of radio which employed frequency modulation. Withers wanted the FM types by 1 March and 15 March deadlines.39

Thus, in consequence of Armored Force demands for the latest and best in radio, the Fort Monmouth Laboratories were reporting by January 1942 that the design of vehicular radio sets “has undergone a marked change”—rather an understatement. It had been revolutionized from amplitude modulation to frequency modulation, going over to a totally new type of smaller short-range set affording better communication, radiotelephone exclusively of course, with less interference, operating in the very high frequencies. The use of numerous crystals, each of a size greatly reduced from prewar types, permitted instant selection of any ten channels from an available total of 80 in the case of the 500 series. By the end of March, Armored Force units were receiving these sets from Western Electric in the hundreds each week.40

The first of Field Artillery’s 600 series sets came out in 1942 after the artillerymen, having seen the 500’s, had asked for similar radios modified to operate in Field Artillery’s frequency band having 120 channels. The SCR-608 got its tests at Fort Monmouth during 25-28 February 1942 and proved rather better even than its prototype, SCR-508. Meanwhile, Field Artillery rushed plans to issue the new 600 sets to all its units by the end of the year, to replace in particular the SCR-245,

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incidentally at a cost of about $1,450 more per set. The new-fangled frequency-modulated 608 cost at first about $2,400, quite a sum at that date for a maze of wire and parts comprising one transmitter and two receivers, the whole occupying but some three cubic feet of space.41

While the 608’s largely relegated the SCR-245 to the background in the Field Artillery, the somewhat smaller frequency-modulated SCR-609 similarly replaced the SCR-194, which had served for some years as the artilleryman’s walkie-talkie. Early in January 1942 artillerymen at Fort Sill, Oklahoma, ran comparative tests on the two radios, especially as used by a gun spotter flying in a reconnaissance plane and reporting to ground. The 609 proved to be much the better set.42

The story of Infantry’s famous walkie-talkie, the SCR-300, an FM set and successor to the foot soldier’s first walkie-talkie, the SCR-195, lies principally in 1942, though production sets would not reach the field till 1943. On the other hand, the first beginnings of the set go back to 1940 when the Signal Corps Laboratories undertook project 10-3, radio set SCR-300, entitled Ultra High Frequency Sets for Front Line Use. But efforts to develop, at that time on AM circuits, a nettable set which would work up to a seven-mile range and which would weigh not more than twenty-five pounds proved unsuccessful. The Infantry thereupon was induced to moderate its SCR-300 characteristics. In December 1941 the Infantry scaled down the required range to only two miles while increasing the weight limitation to thirty-five pounds. Four manufacturers were willing to attempt a very high frequency radio to meet these characteristics, two of them (Hazeltine and Wilcox-Gay) making the attempt with standard AM circuits, two (Galvin and Philco) taking a fresh departure with the new revolutionary FM circuits. It would be Galvin’s FM service test offering which would win out in the SCR-300 competition. Galvin held already a head start in FM development since the company had acquired much experience in the new type of circuits as it built AF-IV, SCR-509 and 510, which the Signal Corps Laboratories had designed and developed. Moreover, Galvin now enjoyed the skill of a foremost FM designer, Daniel Noble, the one who had suggested that the Connecticut State Police try FM and who had thus helped to launch FM vehicular radio upon its spectacular career.43

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The SCR-300 (Above) and 
the SCR-536 (Below)

The SCR-300 (Above) and the SCR-536 (Below)

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While infantrymen had to wait until 1943 before they got their first FM portables (hand-tuned VHF, on 40-48 megacycles—the SCR-300’s), they received several AM field sets: the SCR-284 and its temporary substitute SCR-288, the SCR-511, and the SCR-536. The 511, designed originally for Cavalry, and the 536 for parachute troops, both became standard Infantry sets.44

The SCR-284 was not, of course, portable in the sense that the 511 and the 536 were; several men had to back-pack the 284 and then set it up as a stationary field station. But either the 511 or the still smaller 536 a single soldier could carry and operate as he walked. In fact, the five-pound 536 had been designed for one hand and the men dubbed it the handie-talkie by analogy with the older SCR-195, the original walkie-talkie.45

Three hundred of the very first handie-talkies built by Galvin apparently went to the Dutch in the East Indies early in 1942. A few days after Pearl Harbor Lt. Col. N. J. C. Tierie of the Netherlands Purchasing Commission in Washington asked that the United States Army permit Galvin to divert 200 sets for the parachute troops of the Netherlands Indies army in Java and 100 sets for the Marine Scouting Patrol at the Soerabaya Naval Base. Tierie first met with refusal (the Signal Corps itself had not received a set as of 23 December 1941). He persisted and in January Colonel Colton recommended that the Chief Signal Officer allow the diversion of the 300 sets since Galvin was by this time producing 50 sets a day.46

The handie-talkie was destined to serve as an Infantry front-line set, although it had been launched as Signal Corps’ first tentative answer to Army’s request for a very small radiotelephone which parachute troops might use. In fact, some at first regarded it with no great enthusiasm since Col. Rumbough had described it, in October 1941, as a “stop-gap” radio, which Infantry would tolerate only until it got a more satisfactory, specifically a more powerful, set. At the same time Air Corps men looked sourly upon any such paratroopers’ set since they “very strongly objected to receiving tactical orders from every ‘lance-corporal’ of the parachute troops” who might, for example, have the audacity to ask for bomber support.47

Galvin, manufacturer of Motorola radios and specialist in automobile receivers, built both the 536 and the 511, which were alike in that each was a single-frequency set, crystal controlled, operating in high frequencies 3-6 megacycles. The SCR-511 was an odd little radio, not to say a bit anachronistic, built around a guidon staff which a cavalryman, it was intended, would carry mounted, resting one end of the staff in a stirrup. Yet it was not used on horseback but in the hands of infantrymen either afoot or in jeeps. Beach parties and

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boatmen participating in amphibious operations also used it. The Signal Corps prepared the procurement specifications and standardized SCR-511 in January, issued a letter of award to Galvin in February, and by the middle of 1942 production began.48

The early months of 1942 saw coming into use nearly all the SCR communication sets which would serve American forces in World War II. The laboratories were at work on newer and better developments, some of which would appear in the field before the war’s end as AN types.49 But the great majority of combat radios were the SCR’s, which had by now passed through the development stage and were in production.

Now to shift from the smallest of the SCR’s, the five-pound handie-talkie SCR-536, to the largest, the SCR-299. The 299 had at least one point in common with the 536—it too had developed as a stopgap, only to prove invaluable and indispensable in its own right. A giant mobile set, filling a truck and a trailer, putting out three to four hundred watts of power compared with the 536’s one-fourth watt, the SCR-299 satisfied Armored Force need for AF-I, rendering unnecessary the contemplated development of AF-I originally planned as SCR-505 in the 500 series. The 299 came to be used by everyone and his brother, not just by the Armored Force alone, but also by the Infantry, by the Air Forces, and by the Allies. Production began in the early spring of 1942, when Hallicrafters delivered the first model in March and more than a hundred in April.50

The SCR-299 could travel anywhere its truck transport and trailer, carrying its excellent power plant, PE-95, could negotiate. Its mobility, then, accorded perfectly with the needs of America’s new motorized armies. Moreover, its power and reach were impressive, not just “100 Miles in Motion” for which the Signal Corps Laboratories had developed it. On selected high frequencies using sky waves, the 299 could fling Morse code signals for many hundreds of miles; this, of course, in addition to serving as a reliable radiotelephone up to 100 miles.51 Its range put it in a class with the smaller of Signal Corps’ fixed transmitters, which contributed to Army’s world-wide communication networks.

For fixed radio stations, providing long channels (continuous wave only) for military purposes, the Signal Corps employed commercial transmitters and receivers, either unaltered or only slightly modified to meet military characteristics. A common receiver, for example, was the Hammarlund Super Pro,52 used in its commercial

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form or adapted as the SCR-244, which served Army’s intercept and fixed receiving stations all over the world. As for the transmitters, the choice related directly to the distances which a given installation might be called upon to cover. For relatively short distances of 100 miles or so there was the BC-460, a 200-watt job built by Collins Radio. A commercial 250-watt Collins transmitter, the 30-J, with two Super Pro receivers, constituted the first equipment assigned to 2nd Lt. C. V. Connellan and his team of Signal Corps men serving the Engineers along the Alcan Highway in 1942.53

For really long-range communications the Federal Telegraph and Radio Corporation provided the Signal Corps with BC-339, a 1-kilowatt high-frequency transmitter, employed in Hawaii, Alaska, Iceland, and Puerto Rico. Coupled with the power amplifier BC-340, this set became a 10-kilowatt station. Such was Army’s transmitter in Hawaii, at Fort Shafter, in 1941.54 Such also was Army’s first radio in India, installed by the 835th Signal Service Company at Karachi early in 1942—the first Signal Corps radio in the China-Burma-India theater which could span the skies to the United States, though it could do so only sporadically. According to Maj. Paul C. Davis, this “Federal Telegraph Transmitter, consisting of one BA-22A rectifier, one radio transmitter BC-339-A and power amplifier BC-340-A serial No. 4, functioned exceptionally well at all times, requiring only routine maintenance.”55

Still another Federal Telegraph transmitter built for the Signal Corps was BC-447, a 300-watt high-frequency job much employed in China-Burma-India for communication both within the theater (within and between points in India and China) and outside, to points in Australia especially. Globe Wireless built a 2.5-kilowatt high-frequency transmitter, of which the Signal Corps ordered twenty-five sets in April 1942.56

Such are examples of the fixed radio equipment which provided Army’s communication and administrative needs, serving in the corps headquarters throughout the States, in Army posts among the several possessions, and in the theaters of war. These items of equipment also served AAF airway stations. Because they were commercial items and because they were not needed in great numbers, their production and supply were not at all comparable to the hectic situation touching the SCR’s. For example, only 136 BC-365’s (a medium frequency 300-watt transmitter built by Federal Telegraph and Radio Corporation) had been ordered by early 1942: 31 on a 1939 order, 55 on a 1941, and 50 on a 1942 order.57

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These fixed radios were telegraph sets, either hand-operated, by Signal Corps men pounding out dah-dits on brass keys, or semiautomatic, served by high-speed Boehme equipment. In either case they provided old-fashioned single-channel radiotelegraph, or continuous wave, communication, which was neither very fast nor very efficient, as judged by the later standards of radioteletype. This was true of all Signal Corps’ large radio installations, as in Washington, San Francisco, Hawaii, the Philippines, and a number of other large central military establishments. Signal Corps radio equipment of greater power than the SCR-299 was of commercial design.58

Hitherto, 10 kilowatts was the maximum power output allowed any Army radio station. Until the spring of 1942 only the Navy, within the military family, was permitted to shout in the radio spectrum with a louder voice. Navy had long employed very powerful radiotelegraph stations, up to 40 kilowatts, to communicate with its world-navigating ships. The Army had not previously wandered so far or so wide on the continents of the globe. But now it would, and by virtue of emergency needs, Signal Corps radio for the first time exceeded 10 kilowatts. Numbers of Press Wireless 15- and 40-kilowatt transmitters went on order. On 1 May the Chief Signal Officer announced in his monthly Information Letter that “purchase of a number of 40-kilowatt high frequency transmitters has been initiated for use on long distance radio circuits to task forces. The highest power used previously by the army consisted of 10-kilowatt radio transmitters. These transmitters are being made by Press Wireless and are similar to transmitters they use for their news service to all parts of the globe.”59

Radio Airborne

In the Signal Corps Aircraft Radio Laboratory (ARL) at Wright Field, Ohio, two of the most important radio developments early in 1942 were copies, SCR-522 and 578. Even the work of copying, ARL left largely to industry, limiting itself to the work of testing and adapting industry’s products to Air Corps’ special needs. There was, of course, one large exception, command radio set SCR-274-N, which the Signal Corps, the Navy, and the Aircraft Radio Corporation had created together. It was the only powerful command set (succeeding the SCR-183 and 283) available to American aviators at the beginning of the war, pending American production of the British VHF set, SCR-522. The 274 had been in production since June 1941. A huge number—huge, that is, compared to pre-Pearl Harbor standards—had been built in the last six months of 1941. The number totaled 2,722 sets, this being the quantity that Aircraft Radio Corporation had delivered through 3 January, coming very close to the schedule, which called for delivery of 2,850 by 31 December, out of the total on contract, 28,142.60

The 274 proved to be an excellent

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high-frequency aircraft voice radio. Nearly a year earlier, when the Air Corps first began pressing the Signal Corps to adopt in toto the British VHF system, including the VHF crystal-controlled command set, Lt. Col. Harry Reichelderfer had spoken up for the American SCR-274. The ARL, he pointed out, already had a project under way to provide VHF components which could be used interchangeably with the 274. And the fact that the 274 did not use crystal control he thought a point in its favor, since the supply of crystals seemed most critical at that time.61 Though VHF and crystal control won out, the SCR-274 saw a very great deal of service in the war, especially in such areas as the Pacific where it was not necessary to coordinate with British VHF. In March 1942 Col. Alfred W. Marriner, AAF Director of Communications, informed Lt. Gen. Henry H. Arnold that “the SCR-274N is a new Army-Navy Standard Command set which has been giving excellent service since its adoption.”62 He added, however, that frequency control gave some trouble. “The SCR-274N,” he told Arnold, “required careful setting on the ground. I suspect that because of inexperience, due care is not fully exercised in setting these equipments with a result that all the transmitters being used in a squadron or flight are not on the same desired frequency.”

Although the 274 deliveries at the time of Pearl Harbor were up to schedule, that schedule, like most prewar planning, fell far short of what was now wanted. Faced with the realities of war, the Air Corps was demanding not mere thousands but tens of thousands of SCR-274’s. Pressed for faster delivery, Aircraft Radio Corporation asked Col. John H. Gardner, director of the Aircraft Radio Laboratory, to call a conference toward relaxing specification limits and to consider substitution for critical materials. The conference was called on 11 March. Gardner reported that some relaxations were allowed when “advantageous, particularly if delivery schedules are to be improved.” But this was a solution that could scarcely be afforded. Equipment, if inferior or downright defective, no matter how improved or modern its design, is worse, if it does not work, than older equipment which does function. A reminder of this occurred when the ARL received several receiver and transmitter components of the 274 which were worthless because of defective insulating elements.63

With far more ardor, the Air Forces pressed the Signal Corps for SCR-522, American version of the British VHF command set. For radio control of aircraft the British had gone to frequencies above 100 megacycles (the high-frequency SCR-274 originally went only up to 20 megacycles). VHF embraced more than just command sets for talk between aircraft, together with ground sets so that controlling officers on the ground could direct planes toward the enemy or assist friendly pilots back to their fields. It included also a complex net of VHF direction-finder stations on the ground, whose operators took bearings periodically on an intermittent signal emitted by friendly pursuit planes every few seconds and transmitted over one of the four channels built into each VHF command set. The

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gadget which automatically emitted the signal, the British dubbed “pipsqueak”; Americans called it a contactor. All this equipment the Signal Corps was feverishly pressing to produce for airmen, who were frantic for it even before Pearl Harbor.

The ground elements, fixed and mobile VHF radio sets, VHF direction finders and a complex of control center equipment, all constituting SCS-2 or SCS-3 sets, were the worry of the General Development Laboratories at Fort Monmouth.64 The airborne components concerned the Aircraft Radio Laboratory, which specialized in all the troubles that arise when electronic equipment goes aloft where ethereal conditions impose many a problem unknown to earthbound electric circuits. The simplest airborne component of VHF, pipsqueak or contactor unit BC-608, gave little trouble and was in production by January 1942.65 But not so the SCR-522. This was a precise set having four channels and covering an extraordinarily wide band of frequencies, from 100 to 156 megacycles. The British had originally contemplated two sets to cover this great range of frequencies, all of which the multiple needs of aircraft communication required. But the Americans had believed it possible to cram the entire band range into one set. Rives had argued for this and won his point.66 American laboratories succeeded in a feat of collapsing two sets into one, occupying no more space and weight than the original British TR-1143 had taken up and with only half the ultimate frequency coverage.

The AAF demand for SCR-522 did not stand alone. The British wanted quantities of these copies of their VHF command set too. In this, as in other cases where they pressed the United States to copy their equipment, they had the good reason that they wished to extend their production sources. If American equipment were interchangeable with theirs, they could fall back on American factories when and if their producers were bombed out. Already, two months before Pearl Harbor, General Olmstead had informed the Assistant Chief of Staff G-4 that the recently standardized SCR-522 was in immediate demand both for U.S. Army airplanes and for the British, who wanted 5,000 sets. The Air Ministry, because of destroyed factories, Olmstead said, “is relying upon deliveries under Lend-Lease to provide 250 sets per week beginning the first week in January, 1942.” Olmstead asked G-4 to hand down a decision upon the allocation of monthly production between the United States and the United Kingdom. Even though America was not yet at war, the AAF would grant the British no sets till its own immediate needs had been met. General Arnold on 10 October had ordained that no sets could be spared before 1 June 1942.67

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Bendix Radio undertook the first contract for SCR-522, beginning deliveries in March when the Aircraft Radio Laboratory put them to test, found minor defects, and corrected them in collaboration with the manufacturer.68 By the end of the month production was mounting. Rives informed the AAF that “one hundred fifty-two (152) Radio Sets SCR-522-T2 had been delivered on March 31. It is anticipated that twenty-one (21) more will be delivered tomorrow and that in addition eight (8) SCR-522-A will be delivered tomorrow. Production is beginning to roll on these sets now,” Rives wrote, “and it is believed that they will rapidly build up to quite a sizeable figure. The above figures,” he added, “apply only to Bendix Radio Corporation itself. A number of subcontractors are being utilized to assemble complete radio sets, but it is not believed that any sets will be delivered by the subcontractors for approximately one month.” He estimated that within three months the total output of SCR-522’s would attain a peak of 3,000 monthly.69

Rives may have been a bit overoptimistic. Production figures for the 522 did not begin to appear in the weekly summaries of the Statistical Branch, now under Services of Supply, until the week ending 22 April. Nor did they snowball as fast as he had anticipated. Bendix was at first the sole producer, whom for some reason the British had preferred. Producing this American copy of a British radio raised difficulties comparable to the troubles American manufacturers were having imitating British radars. British insistence on secrecy was one difficulty, as Olmstead had pointed out to the Under Secretary of War in October 1941. “The British,” he said, “have insisted that a high degree of secrecy be maintained on this equipment. ...” He went on to describe it as “of strictly British origin, the American action being limited to redesigning the set to adapt it to our manufacturing process to use American parts and tubes and to increasing the frequency band covering from 100 to 124 megacycles to 100 to 156 megacycles.”70

Just as the SCR-522 was a copy built under the supervision of the Aircraft Radio Laboratory, so too was the SCR-578, the curvaceous “Gibson Girl,” saving angel of many a wrecked aircraft crew adrift on the sea. Ironically enough, a German set gave the idea. One day in 1941 the British had picked up an emergency transmitter from the English Channel. It was the Notsender, N.S.2, an ingenious watertight portable transmitter to which a waterlogged airman could give energy by grinding a crank, energy which would automatically broadcast a distress signal to friendly listeners up to several hundred miles away. The British had brought the captured set, along with a specification written around it, to America in mid-1941, seeking a manufacturer either in Canada or in the United States. With their predilection for Bendix, they had approached Bendix Aviation Limited, North Hollywood, California, to undertake development of this “dinghy transmitter,” as they termed it. Both Army and Navy became interested after members of the

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The SCR-578, Gibson Girl 

The SCR-578, Gibson Girl Radio. Distress signals were automatically transmitted when the crank was turned (left) and the antenna raised (right)

British Air Mission in Washington suggested in August that the Americans prepare a joint specification. The Air Forces, in response to the Chief Signal Officer’s request for military characteristics, had at once evinced interest. The interest swiftly mounted to a demand after Pearl Harbor. While Lt. Col. George F. Metcalf in the Research and Development Division on 12 December urged the Signal Corps Technical Committee to take action on military characteristics without waiting for the Joint Radio Board to function, General Arnold asked on 24 December for 11,600 sets “as soon as humanly possible,” requesting the Signal Corps to place a contract with Bendix Aviation Limited, taking advantage of the development which that company had already accomplished upon the original British specification.71

While the Signal Corps set about getting the transmitters (deliveries began in the last week of May 1942),72 the procurement of antenna-raising equipment gave pause, and trouble. The 300-foot antenna wire had to be lifted into the air, either by a kite if the wind was blowing, or by a balloon inflated by the castaways, crouched precariously in

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their rubber boats. General Olmstead, under pressure from the AAF, repeatedly goaded the ARL for information as to when antenna equipment might be expected. He could not wait for the drawing up of formal specifications; he wired Gardner on 2 February. Gardner replied that he expected Bendix to deliver models of antenna-raising equipment on 9 February.73 A few days later Arnold, irked that Bendix’ final sample was not yet completed, pointedly concluded a note to the Chief Signal Officer with the sentence, “A dinghy-load of Army pilots, who are now somewhere in the South Atlantic, could give eloquent testimony to the need for this equipment.”74

By the end of March the Aircraft Radio Laboratory and Bendix Aviation Limited were settling upon a production model when the third sample of the transmitter (BC-778-T2) received tests and approval at Wright Field “except for minor mechanical and electrical changes which can be made prior to or during early production.” As for antenna-raising equipment, Colonel Gardner reported that no satisfactory samples had yet put in an appearance. But he expected something soon, in particular an improved hydrogen generator (to inflate the balloon), using rare lithium, rather than calcium, hydride. Of lithium hydride there was only one source (in the Dakotas) and toward supplying it in quantity the Signal Corps lent government financial assistance to a number of American producers.75

Radar Into the Air for Interception and Search

Here and there along the coasts, ground radar stood guard to alert the guns, searchlights, and interceptors of the defense stations against the approach of enemy aircraft, but airborne radar had yet to go into action. The nation’s defenses were eager for it, because the attack upon an outlying territory had made continental targets seem fearfully vulnerable. The country was primarily apprehensive of carrier-based attack, but the threat of long-range submarines to coastwise shipping became the dominant menace. To meet either threat, radar was what was needed. Moreover, it must be radar which was not obliged to accept the conditions imposed by the attacker, as even the most mobile ground radar had to, but which could move out to find him. To acquire this degree of range and mobility, radar would have to be installed in airplanes.

Signal Corps responsibility for research in airborne radar naturally centered in its Aircraft Radio Laboratory. For several years the laboratory, generally in its Air Navigation Unit, had pursued various projects of what now had come to be air radar devices. The ARL had not itself done much basic scientific research on airborne radar. One of its established principles had always been that it did not study electronic fundamentals. For these it depended upon other research agencies, both of private industry and of the services. In the specific case of airborne microwave radar, for example, it looked to the National Defense Research Committee’s Radiation Laboratory, located in the Massachusetts Institute of

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Technology, Cambridge, Massachusetts.76 But the applied engineering research required after a basic development in order to produce satisfactory military equipment was the laboratory’s concern. Consider the fact that a model might work well on a laboratory bench but not in a hurtling airplane. The business of adapting the model to aircraft installation and to effective operation, while meeting both the military characteristics which the Air Forces demanded and the form which industry could produce, was a function combining applied military and applied production research of a specialized and exacting sort, quite different from the Monmouth laboratories’ development of ground electronic equipment. Equipment which is comparatively simple to develop for ground use, such as antenna arrays, becomes a problem when it must be attached to an airfoil or fuselage. Further problems arise from aircraft vibration, weight and space limitations, and from operation at high altitudes where, in thin air, high voltage circuits tend to arc and break down.77

One of the most vital airborne radar devices, useful in both peace and war, was the absolute altimeter. The SCR-518, which the Radar Unit of the ARL was bringing to a climax at this time, was an instrument which showed the pilot the precise distance to the ground below by measuring the time taken for a radar pulse to touch the earth and return to the airplane. It constituted a vastly better altimeter than the former barometric type which, giving elevation above sea level only, was not a very precise instrument at best and was of no use at all as an indicator of absolute elevation—of actual clearance above the ground. The AAF wanted the radar altimeter principally as an aid to bombing from great altitudes, so as to set the data into a bombsight computer like the Norden. The pulsed type of radar altimeter which the Radio Corporation of America had been developing in the years just before the war had proved to be the answer. The Navy, interested, tried a number of these sets, but at first without much regard for applications other than mere calibration of its barometric altimeters. Thinking in terms of ocean patrol and of low-level bombing, and not of high-altitude and long-range bombardment over land, naval air service planning had tended to neglect the possibilities which the ARL and the AAF immediately perceived.78

In February 1942 while the ARL tested several versions of the absolute altimeter and developed test equipment to keep the sets calibrated for peak performance, the production prototype SCR-518 arrived from RCA factories. Mounted in a B-17 and flight tested, the set gave reliable readings up to 25,000 feet. This was considerably better than the 20,000-foot requirement for

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which the military characteristics called. Still another version performed well right up to the ceiling of the test plane’s rise, 31,300 feet. Even at that altitude, so much reserve sensitivity remained in the receiver’s reception of the ground echoes that the laboratory planned to make further flight tests with smaller antenna arrays which would offer less resistance to the wind.79

Another important project involved airplane identification. It had been obvious since radar’s inception that the ability to detect aircraft at distances far beyond the range of vision would be of slight value unless some means could be devised to distinguish friendly craft. That accomplished, unidentified airplanes would be presumed hostile. To this end the U.S. Army and Navy had already begun work on airborne radar equipment which they called RR, for radio recognition. The British called their somewhat similar development IFF, Identification, Friend or Foe. After the Americans and the British compared notes on radar, the Americans adopted the British terminology, and by 1942 were adopting their equipment also, despite the fact that in some respects the American RR was better. In January, while continuing work on the airborne component of RR, the SCR-515, the ARL also went about converting a considerable number of British IFF Mark II sets to SCR-535’s. By March, the Radar Unit was working also on American versions of a newer IFF, the Mark III and III-G, copied as SCR-595 and 695, respectively.80

Still another airborne radar development at this time touched upon the highly significant matter of RCM, or radar countermeasures. It is an easy axiom that every new weapon of war brings forth a counter-weapon. Radar was not an exception to the general rule. Electronic Countermeasures had been a matter of life or death since the British had begun misleading German night bombers by jamming the guide beams which directed the forays over English cities. It behooved American laboratories, too, to study German and Japanese radar frequencies and other operating characteristics in order to develop equipment which could, in effect, blind the enemy’s sets. On 28 February 1942 British commandos raided Bruneval, just north of Le Havre on the captive Channel coast of France. The purpose of the raid was to bring back to English laboratories a German Würzburg, nemesis of many an Allied plane and the most accurate ground radar in the war until the SCR-584 entered combat in 1944.81

Whether through notice from the British to General Olmstead or from the Radiation Laboratory to Wright Field, or because word was coming in of Japanese jamming tactics in the Pacific, the ARL recognized the importance of RCM at about the same time by setting up a project for “Derax Warning.” (Derax was an early name for radio position finding, which the term radar was now, in 1942, generally replacing). It

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would not be possible for Allied aircraft crews to take effective counteraction against enemy radar, either passively, by evading the rays, or actively, by jamming, until they possessed equipment which could reveal the presence and frequency of radar radiations. The new project, tentatively established pending the receipt of funds, led to the development of a panoramic receiver, the SCR-587, equipped with a radar like oscilloscope in which an operator could see the impact of enemy radar beams and read their frequency.82

The demands of the dangerous defense situation of the early months of 1942, however, were overshadowing these and other remarkable developments, such as navigation by radar. All the problems which the ARL was encountering in the development of airborne radar, sufficiently perplexing in themselves, were now compounded by urgency. The two prime needs were for devices capable of intercepting unseen enemy airplanes and detecting unseen raiders or submarines. Both were about to come off the first production lines. A3, the airborne interception equipment, would enable a pilot to “see” his opponent on the instrument panel, whether he could actually see him ahead or not. ASV, air-to-surface-vessel radar, mounted in a patrol bomber, would show up hostile watercraft even though they might be lurking beneath clouds or darkness. ASV was first included in the BTO, or bombing-through-overcast, project, but was soon given separate effort because of its immediate importance. Air intercept equipment came under a project to develop an airborne aircraft detector.83 Though originally used for purposes of defense, radar now suddenly became an instrument of offense. Its potentialities doubled.

Airborne interception equipment had been an urgent development, it will be recalled, since Sir Henry Tizard first revealed it to America in September 1940.84 It had been the one British radar application totally new to American military electronic research. AI sets, as developed to meet the vehement demands of the U.S. military air organization, were radars of relatively short range which, installed forward in pursuit planes, enabled the pilots both to “see” a bomber several miles ahead and, by centering the bomber’s reflection in their oscilloscopes, to hunt it down. The ARL had two types well in hand by 1942. The first was a long-wave model, calibrated at about 200 megacycles. This was the SCR-540, copy of the British AI-IV. It was not a very good set. For one thing, its one and a half meter wavelength required large external antennas, a bane to aircraft design. All through the last half of 1941 the ARL and Western Electric had had difficulty in adapting this American copy of a British set to American airplanes. They were still having trouble as 1942 began. In January Western Electric samples of SCR-540 components failed vibration tests and had to go back to the factory for modifications.85 By March the first 80 sets under contract were supposedly so nearly ready that Colton, Acting Chief Signal Officer during General Olmstead’s westward tour, set up a priority list for their delivery to radar training schools. Yet only five sets arrived. And in each of them a single component, the

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General Electric inverter, failed in high altitude tests.86

The Aircraft Radio Laboratory’s other AI set, the SCR-520, employed microwaves ten centimeters long, in the frequency range around 3,000 megacycles. It was a much better radar and became available sooner than the SCR-540. When the Tizard Mission brought over the cavity magnetron and asked American help toward designing workable radar circuits for it, London had just then defeated the Luftwaffe day raids and was awaiting Germany’s night bombers. Faced with the need for a better air intercept set than their long wave AI-IV, the British sought it in microwave equipment. As soon as the Bell Laboratories could produce the new magnetrons for generating powerful microwaves, the Radiation Laboratory had gone to work on a ten-centimeter AI (AI-10) and had come up with a model of it early in 1941. Tested at the ARL, this model attained considerable success despite its awkward bulk. Though heavier—it weighed about 600 pounds—than the SCR-540, the new ten-centimeter SCR-520 used a compact dish-like transmitting and receiving antenna array, two feet in diameter, which could be mounted wholly within the plane’s nose. In performance, this microwave AI radar gave more distinct reflections from targets and suffered far less interference from undesirable ground reflection. Taking a page from British success with equipment built in a laboratory, that is, “crash-built,” the Signal Corps had ordered a number of sets from Radiation Laboratory’s own shop, the Research Construction Company, and had already begun receiving them. Meanwhile, the ARL went ahead toward the construction of hundreds of SCR-520’s on contracts with Western Electric, which, in December 1941, had delivered a preliminary production model.87

In Air Forces demands, however, AI was receding in priority. Submarines, not airplanes, were bringing the war to the Western Hemisphere, and the Air Corps, which in 1941 had wanted what applied to the war situation of 1941, but which had been obliged to wait for the planning and manufacture of this equipment, now had the same problem in a 1942 situation. General Arnold, chief of the Army Air Forces, was confronted with a double embarrassment. In the first place, he was not getting antisubmarine equipment. In the second, he was getting air interception radars. He had asked for them, but now found he had no airplanes ready for them. Here was the Signal Corps, offering more sets of the newest and best AI radar than the AAF knew what to do with. Quietly store them, or something, Arnold advised his Director of Air Defense, Col. Gordon P. Saville, lest the Signal Corps return with interest the accusations which the Air Forces had been in the habit of lodging with the top Army command. “The first thing you know,’’ Arnold wrote, “we will have a complaint being registered by the Signal Corps to the Secretary of War. Isn’t it possible to take the AI-10’s and put them in storage in our own warehouses, or do something along that line, so that the Signal Corps won’t have reason for their present feeling of

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Airborne AI-10 radar, 

Airborne AI-10 radar, SCR-520

‘what’s the use of producing these sets when all we do is store them away.’ ”88

Both to the American in the street and to the American in the Constitution Avenue war room, the greatest immediate need was for a way to deal with the submarine attacks which were sinking more and more ships, often within sight of American shores. The radar answer was to be ASV. Here again, as with AI, two versions lay in the Aircraft Radio Laboratory’s active projects, a long-wave type and a microwave type. The long-wave version had been another British offering. This was their ASV-II, the radar to which Hitler is said to have attributed the defeat of his submarines,89 although actually the subsequent microwave ASV and the related naval ASG sets did more to send the U-boats to the bottom.

The laboratory already had a copy of the ASV-II under way as the SCR-521 and had ordered thousands of them. The first contract, for about 6,000 sets, was made with a Canadian government firm. Research Enterprises Limited, at Toronto. A second contract had gone to Philco. In

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actual production, however, copying British sets was not at all the short cut which the General Staff and the AAF supposed. Differences in American airplanes and in American components imposed delays. It was difficult to tailor the large external antennas of the ASV-II (SCR-521) to U.S. aircraft, as Colton explained in mid-March, answering insistent War Department demands for ASV. Furthermore, faulty oscilloscopes gave trouble. During the winter months of early 1942, the ARL took preproduction models of the SCR-521 up on flight tests, found flaws in their operation, and had to eliminate the difficulties in concert with the two manufacturing companies. Before the factories began mass production of the thousands of 521 ‘s on order, the ARL also mounted, tested, and made ready for operation a number of the ASV-II prototypes which the British had sent over more or less complete some months earlier.90

Throughout the first three months of 1942, the Army had to be satisfied with the copy of ASV-II, the long-wave SCR-521, if indeed the Signal Corps could lay hands on it at all, for it was something of a will-o’-the-wisp. Research Enterprises Limited had originally promised to start delivery in December 1941, but subsequently moved the date up to January. When February arrived, while coastal shipping continued to be sunk in increasing quantity, there were still no SCR-521 ‘s, the nearest thing to them being the several British prototype sets which the ARL was adapting.

Pressure meanwhile doubled and redoubled for Army ASV-equipped airplanes, not only so that they could sink submarines but so that they might also maintain patrols, constantly searching the sea for Japanese aircraft carriers along the Pacific coast and in the Panama area. Late in January 1942 Robert A. Watson-Watt, British radar expert, reporting on the Pacific coast air defenses, recommended to Robert A. Lovett, the Assistant Secretary of War for Air, that both Army and Navy aircraft get hold of ASV-II, as a matter of “highest urgency,” in order to maintain unceasing patrol. On 10 February Harvey H. Bundy, special assistant to Secretary Stimson, urgently telephoned the Signal Corps’ Radar Division, seeking to find out why the delivery was so belated. General Colton at once had Lt. Col. Gilbert Hayden describe the entire ASV situation. Of the prototype ASV-II’s, Hayden told Colton, four had been installed, ten were ready for installation whenever the AAF could supply the planes, and 18 more were awaiting transmission cable. As for the thousands of SCR-521’s on order, Research Enterprises Limited had last promised to deliver between 50 and 100 before the first of March. The Navy had already received nearly 200 sets (not all of them complete) on a prior contract.91

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SCR-521’s from Canada at last began to dribble into the ARL during the first week of March. Meanwhile, ship sinkings were terrifying. The Navy’s antisubmarine operations by sea and by air were not enough. In fact, the Navy was somewhat behindhand with the new airborne radar applications. Because of general military ignorance of the new offerings of science, the Navy had so far failed “in making full offensive use of new airborne weapons and devices in the pursuit and destruction of the U-boats.”92 Fortunately, Secretary Stimson kept goading the rest of the military to keep up with the times. On 18 February War Department planners received a memorandum from Bundy awakening them to new developments whose progress was both so secret and so rapid that “important officers of the General Staff and especially those in War Plans Division have not been and are not currently advised of their existence, functions and effect on strategy.” One of the examples which Bundy cited was the use of “airborne search radar as an additional defense for Panama.”93

Therefore, it is not surprising that by March, since the Navy could not yet cope with the submarine and as the General Staff learned more about airborne radar, the War Department was putting increased pressure upon the AAF and the Signal Corps. On 16 March Lt. Gen. William S. Knudsen, one of the chiefs of war production, called upon General Colton for a report. Colton again collected the facts, this time from Colonel Gardner at Wright Field. Twenty-seven SCR-521’s had now been installed, although the Air Forces had not yet been able to decide what type of airplane should be used for ASV. A major obstruction had been lack of the several antennas required; another was an insufficiency of men and time to do individual installation. The antenna shortage went back to an inadequate allotment of steel tubing to the manufacturers and to an insufficiency of insulators. As for trained installation crews, the ARL had only one, whose members could put in but a single set a day. To train additional crews would require several weeks. Altogether, the most Gardner could foresee was that about 150 antenna sets would be on hand and 33 installed by mid-April. All of this Colton passed on to Knudsen, only to receive another call on the next day, ordering the delivery rate to be doubled. Gardner immediately got the word, and was told that he would be given double-A priorities to break any bottlenecks.94

Meanwhile, very great effort was being concentrated upon microwave ASV. Prior to 1942 both the Aircraft Radio and the Radiation Laboratories had accomplished a good deal with ten-centimeter BTO and ASV equipment. But no sets were ready for use. Fortunately, a ready stopgap lay at hand. One could convert AI-10’s into ASV-10’s, taking some of the sets which the Research Construction Company had already built and for which the AAF had no great use at the moment. One could then

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put the converted sets into large airplanes, installing them in blisters beneath the fuselage so that the parabolic reflector would project the microrays downward and the antenna dipole would receive echoes from objects upon the sea. Accordingly, Colonel Marriner, the AAF Director of Communications, had sent a request through the Signal Corps to the Radiation Laboratory “to modify ten service-test AI-10’s into ASV-10’s as soon as possible” for installation in B-18’s, which workers at Wright Field were already modifying. In forwarding the request, Hayden had assured Dr. Edward L. Bowles, head of the Radiation Laboratory, that the Aircraft Radio Laboratory would cooperate toward fabricating the correct accessories and installing the complete sets without delay.95

The job was done under the utmost pressure on all sides. The two laboratories completed the conversion in two months, and on 27 March one of the B-18’s flew over Block Island Sound to test its ASV-10 against the submarine Mackerel. The echoes came back reliably at ranges up to nineteen miles. By the end of the month, four of the ten bombers thus equipped were in operation out of Boston, and the remaining six at Langley Field, Virginia.96

Designated SCR-517-A, these ten sets were as phenomenally successful as the Army’s first microwave AI-10 had been in mid-1941. The success of AI-10 had been somewhat academic, however; there were no enemy night bombers over the United States. But in the spring of 1942 there were live submarine targets off U. S. coasts. These original microwave ASV’s could and did draw blood at once. Their service tests coincided with combat action. The ASV-10, on the assertions of some, sank its first submarine on 1 April 1942.97 A few days later Colonel Marriner asked the Signal Corps to get 100 sets of ten-centimeter ASV’s, either standard SCR-517’s or modified SCR-520’s, and demanded that they receive a priority “over any other radio equipment now being procured.” Speaking of “standard SCR-517’s,” Marriner meant the other microwave ASV development upon which the Aircraft Radio and the Radiation Laboratories had been working for some months. When one of these sets had been mounted in a B-24 in the spring of 1942, Secretary Stimson himself accompanied it in a test flight. He returned confirmed in his

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Air attack on a submarine

Air attack on a submarine. Such attacks were frequently the result of airborne radar discovery of the enemy

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enthusiasm, and redoubled his drive to introduce the sets.98

Ground Radar: The Continuing Exigencies of Coastal Defense

When Field Laboratory No. 3 in the area of Sandy Hook became the Signal Corps Radar Laboratory in January 1942, it had thirty-six ground radar projects under way. These projects were intended to serve a variety of functions. They were for directing searchlights, SLC sets SCR-268 and 541; for giving early warning of approaching aircraft, EW sets SCR-270 and 271, together with several modifications under development to determine target elevation; for detecting surface vessels, coast defense (CD) sets SCR-296 and 582; for ground-controlled interception, GCI sets SCR-516 and 527; for gun-laying, GL sets SCR-545, 547, and 584; and for identification, RR sets SCR-532 and 533, designed to query the airborne SCR-515. Radar was rapidly growing and changing. Three radars were so new at this date that the laboratory had not yet assigned them project numbers. Of these, two were developments of microwave circuits which the Radiation Laboratory had created about the cavity magnetron. These, the XT-3 and XT-1 sets, became, respectively, the SCR-582, a fixed radar for harbor protection, and the SCR-584, the remarkable mobile gun layer. The third set was the long-wave SCR-588, at first a copy of the British Chain Home Low, or CHL.99 This copy was being built in Canada by Research Enterprises Limited, which was also helping to produce the airborne SCR-521 ASV-II radar. It had been requisitioned by the Army Air Forces and was already part of a dispute which reached a climax that spring.

In the 268, 270, and 271, the Signal Corps Laboratories had developed ground radars which for their day were very good. The Coast Artillery Corps was well satisfied with the SCR-268 for searchlight control. But officers of the Air Corps who had seen British CH or CHL sets, or who had heard enthusiastic descriptions of their applications, tended to dismiss the SCR-270 and type 271 as a “piece of junk.”100 Generally, during 1941 and early 1942 they wanted Chinese, that is, exact, copies of British sets.

Yet the performance of the Signal Corps equipment was individually not inferior to comparable British sets, and in some respects was better. Furthermore, Signal Corps sets were unsurpassed for ruggedness and engineering. Colonel Corput could say with good reason that “at the time that the

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Radio Set SCR-268 was placed in production, insofar as is known, there was no radio set in the world equal in performance.”101 It was compact and mobile and could determine azimuth, nearness, and elevation for ranges up to 24 miles. During 1940 and 1941 it had been the best searchlight control radar in existence. The SCR-270 and 271, built to use a three-meter wavelength, twice that of the 268, were slightly less successful in earlier models, but they too were rugged. Moreover, the 270 was mobile. It had plenty of power and a range extending to 150 miles, and completely met the early requirements of the Air Corps for detection of aircraft at long ranges.

Unfortunately, the Americans had not yet learned how to use it well. The British, on the other hand, working with large teams of researchers and military users, on a scale undreamed of in the United States before 1940, had learned to make full use of their fixed radars to an extent which America had not yet done with its mobile sets. The same British radar towers, if erected along the Florida coastline, might well have defended a comparable area from air attacks originating in Cuba or the Bahamas; but an entire continent would still have stretched undefended beyond. British CH radars could not move to new locations. The SCR-270 could. In the absence of any attack, and in a geography vastly different, American radar had not yet begun to capitalize its virtues or to understand its limitations. To have an SCR-270 which could determine elevation as well as azimuth and range would be good, the AAF thought; it would be better if the set able to do all of this were also mobile.102 Yet the two attributes could not be combined in a long-range long-wave set. The British equivalent of the 270, the CH stations, gave approximate target elevation, but at the cost of mobility, for they had to use several antenna arrays which pinned the sets to very fixed positions indeed.

There were also various inherent limitations of the early radars which scientists did not at first understand. Army Air Forces observers, for example, had been impatient with what they felt to be the limited performance of radar during the late-summer Louisiana maneuvers of 1941. Lovett and Bundy had accordingly been hard on the Signal Corps. A widely shared ignorance of the abilities and limitations of mobile radars had led Lovett to write an adverse report because the sets could not detect airplanes approaching at levels below 3,000 feet. Soon afterward, Bundy had called upon Lt. Col. Eugene V. Elder in the Materiel Branch for facts. These Rex Corput, then a major and the director of the Signal Corps Laboratories, had supplied. At the maneuvers, he pointed out, SCR-270-B’s were detecting airplanes at elevations as low as 700 feet when the planes were as far as 35 miles away, and at elevations as high as 5,000 feet when the planes were as much as 100 miles distant. This constituted good normal performance for a radar, which of course cannot be expected to “see” over the curve of the horizon, because very high frequency radiations follow the line of sight tangent to the curve of the earth. The performance in Louisiana seems even to have excelled that of British detectors in respect to low coverage. “It is of interest to note,” Colonel Colton remarked concerning Lovett’s criticism, “that the low pickup angle

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of the SCR-270-B’s is one third that of the long-range British equipment for equal heights of site.”103

Weaknesses in the early American ground radars lay more in their application than in the sets themselves. Skilled crews could get excellent results with them, but few operators of that sort were yet available. In England, there were very many, women, as well as men, who were both trained and battle tested. In the American forces, although Signal Corps crews had been operating 270’s and 271’s spotted along the coasts of the United States, Iceland, Panama, and Hawaii, they had often lacked adequate training, as Private Lockard’s Sunday morning practice at Pearl Harbor had illustrated. Moreover, the commands responsible for defense doctrine knew little more about the potentialities of radar than the untrained operator knew about the individual set. Admittedly, air defenses were poor.

During the first two weeks of January 1942, and at the request of Lovett, Watson-Watt inspected the air defenses of the Pacific coast. Watson-Watt, then the foremost British radar authority and the engineer who had proposed in 1935 the aircraft detection system which produced the CH stations, was scientific adviser on telecommunications to the British Air Ministry. Accompanied by Colonel Saville, one of the AAF’s most vigorous advocates of radar, he hurried through a speedy inspection and followed it by a devastating report. The report was a bombshell. Blasting Signal Corps radar equipment and radar training, it exploded also against the AAF, the General Staff, the Western Defense Command, the Coast Artillery Corps, and everyone else in sight. Watson-Watt, a brisk little Scotsman of alternating ability to charm and to infuriate, saw nothing good in American military radar.

Watson-Watt saw a multitude of reasons why American radar, radar sites, radar organization, radar planning, and radar operators were not good. He pointed at shortcomings in operators (“ill-selected, ill-trained, inadequate in numbers, and only transitorily within [the] Western Defense Command”). He noted bad planning at top levels, declaring that the distribution of responsibility for planning between the War Department and the commands was indefinite and illogical and singling out staff deficiencies in several other respects. In his opinion, the higher commands did not realize the inherent technical limitations of radars. “There is no sufficiently firm staff realization,” he said, for example, “that Radar screen can be made to give smooth continuous tracking in high raid densities; that the provision of individual stations each working technically well would not suffice to produce a coherent system; that such a system is essential to controlled interception by pursuit units; and that controlled interception is the only economical system of air defense.” He observed in particular that the site is such an integral part of the radar station that it all but controls the performance and, in making this observation, added, “For this reason, Radar can never be truly mobile.”

He swept the mobile SCR-270 aside. “The only available shore-based Radar

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screen equipment SCR-270,” he wrote, “is technically and operationally gravely unsuitable. ...” Some of his criticisms of the 270 were justified, although generally they referred to defects to which all long-wave radars are subject. Others were beside the point. In its original specifications, for instance, the Air Corps had envisaged a set for early warning only, but Watson-Watt now objected to the “lack of height-finding means” in the set, which had never been designed to have them. One comment in particular must have stung the Signal Corps radar officers: his assertion that “the average dependable range of location does not exceed 30 miles.”

To some of Watson-Watt’s comments Colonel Corput, now head of the Signal Corps Radar Laboratory, wrote a pointed rebuttal. Taking the matter of the SCR-270’s range, he calculated it at four or five times what Watson-Watt allowed it. “Its reliable maximum range is limited [only] by line of sight or 150 miles, whichever one is the lesser,” Corput said. The higher an airplane flew, the farther an SCR-270 or 271 could “see” it. So low an average dependable range as 30 miles, Corput explained, “would obtain only in the case of a low height of site and a low flying aircraft,” and he might have added that under those circumstances the same would be true of the range of the CH, the CHL, and the new CHL/GCI. Corput granted that on many points the report would be valuable to the Radar Laboratory and to the services which used Signal Corps radars. Yet it was obvious, he added, that it was based on a cursory survey. It was also obvious that Watson-Watt knew nothing of the reasons why the Americans had developed radar as they had. Mobility, for example, had been paramount in the minds of the planners, who had vast areas to defend and who thought in terms of shifting the detectors to this or that threatened area. Corput attributed Watson-Watt’s extreme critical attitude to “a characteristic evident in many engineers, the tendency being to compare the latest developmental equipment which they have seen [in laboratories] with the equipment which they actually encounter in the field.”104

Making use nevertheless of seemingly authoritative contentions, the Army Air Forces continued to urge British radar sets, which they believed superior to anything the Signal Corps had built or could devise. In a 1941 rumpus which had threatened Signal Corps control of electronic development and procurement, the Air Forces had already insisted that the Signal Corps copy the original British GCI.105 A sample had reached Field Laboratory No. 3 in October 1941 and General Electric had taken on a contract for 210 sets; but it would be the spring of 1943 before a production model would actually appear as SCR-527. Watson-Watt’s report had even recommended for some locations the old British CH radar, which “floodlighted” the areas it surveyed with a continuous flow of long-wave pulses radiated from fixed antenna arrays at heights of several hundred feet. For many locations, he declared that the American SCR-270’s on the west coast ought to be

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replaced by British CHI/GCI sets equipped with continuously rotated antenna arrays and with plan position indicators. Research Enterprises Limited, the Canadian firm, was supposed to be manufacturing them in sufficient quantity as SCR-588’s.

The equipment would be a combination set which could be used as a GCI in some locations. Known as a CHL/GCI, it would serve as either but not as both, according to its location. If the site were a high cliff-like spot, the set would be CHL, to provide long-range detection and good low coverage, but not target elevation; if it were a flat or somewhat bowl-shaped area, the set would function as GCI, thereby permitting rough height finding, for control of interceptor planes. But in order to serve as a GCI, the set would require a location almost impossible to find. It was supposed to be placed in a sort of shallow bowl, very flat in the center, level to plus-or-minus four feet for a half-mile radius around the set, level to plus-or-minus eight feet for another half-mile beyond that, and rimmed round at a distance of three or four miles by a low ridge of rising land. In Corput’s words, “A careful reconnaissance covering many hundred square miles in the Northeastern part of the United States has failed to locate an area even approximating this requirement.”106

The CHL/GCI in either usage would be practically a fixed installation, and in this respect a step backward. The requirement for mobility had been written into the original Air Corps request for radar. Subsequent combat experience would prove the correctness of the requirement. But during the early months of 1942, so long as the United States feared for the coasts and thought in terms of fixed protection for them, the Aircraft Warning Service desired a screen like that girding the British home island.

In February Colonel Saville pressed Watson-Watt’s demand that the Signal Corps get CH radars. The British had evolved two less ponderous forms of their original Chain Home, the MRU and the TRU, mobile and transportable radio units, respectively, but even the MRU was not mobile according to American definition. On 18 February, in a spirited conference of AAF, Signal Corps, and British representatives including Watson-Watt, Saville indicated the AAF support of British models:

What is the answer [to early warning and ground control of interception]? We have a more or less mobile piece of equipment in the GCI and CHL that we are talking about that can be interchangeably used simply depending on the site. [But] it does not give the entire early warning coverage that we want. Something else [is] required now. What is the additional thing? In my opinion, it is the thing the British have developed: floodlight of area by MRU.

After suggesting that the Signal Corps procure 100 MRU sets from England, Saville went on to argue for a dozen or fifteen CH sets also, to provide early warning protection immediately to the coastal cities. In this he received support from Watson-Watt’s view that only radar at very low frequencies could detect aircraft at great ranges. “There is no other system known,” the Scotsman said, “than 20 to 30 megacycles which will give us location at 150 to 200 miles ... Low frequency,” he categorically concluded, “is essential to long range.”107 Summing up the air defense

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situation in America, Saville painted a dismal picture:

We do not have sufficient distance coverage, early warning, no control device of any kind; we do not have a sufficient reliability and pick-up of a sufficient distance in any of the forms that we now have. Things are corning along such as gap filling, but until you get them you still have such gaps in the pattern that the performance cannot be relied upon to give accuracy. Whether the 270 can be made into the thing described as CHL, I don’t know and don’t care ... At the present time our view is that it is not mechanically operationally satisfactory and that its early warning characteristics are such that it does not do the job to compare with other equipment. I am talking about part of a system. The 270 is good if you put it on a small island where the problem is not one of tracking but of discovery [but is not suited to continental GCI].

Obviously the Army Air Forces did not much care for American search radars. True, the SCR-270 could not be worked into a GCI system until it could determine target elevation readily and until gaps in its coverage could be filled. But the Signal Corps Radar Laboratory was hard at work at this very time upon such devices, even though the set might be reduced to immobility. The 270 was good, as Colonel Saville admitted, for simple aircraft detection, for “discovery,” as he put it. Despite his implication that its range and reliability were poor, both were good if the set was well operated. Colonel Hayden pointed out in this conference that Watson-Watt tended to exaggerate the range (150-200 miles) of the celebrated CH. The operator of a CH station which Hayden had visited some months earlier in England had told him that the utmost range the station had ever attained was 152 miles, while the average daily maximum was about 110 miles, or just about the usual attainment of the SCR-270 and 271.108

After the surprising and lethal weakness of the Hawaiian air defenses at Pearl Harbor was revealed (a weakness in the radar warning system, not in the SCR-270 itself), American military men, worried before, felt real anxiety. A Japanese carrier attack upon the Canal seemed imminent, most probably at low level. Planes skimming in over the sea would not only escape visual detection until the last moment but would completely elude search radars, too. This fact greatly disturbed General Andrews and his signal officer, General Ingles.

Ingles wrote to Olmstead that he had repeatedly tested the four radars guarding the Pacific side of the Canal, sending low-flying planes in from the sea against them, but had never got any results. If the Signal Corps had any suitable equipment, he wanted to know about it. “As you know,” he wrote, “secret developments are kept so secret that we officers in the field are in entire ignorance of [them]. ...” He revealed incidentally that he did not share the general AAF opinion that British sets were superior, and concluded with a proposal for visual warning stations aboard ships equipped with radio.

A week later Olmstead answered, assuring him that the Laboratories were at work on solutions. As for the alleged superiority of British equipment, he thought it “not a question of difference between English and

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SCR-268 at Pacora, Panama

SCR-268 at Pacora, Panama. Set is shown as positioned in April 1942

American equipment, but rather a question of the condition under which the respective equipments have been tested.” The British CHL, he granted, did handle low-flying planes “reasonably well,” not only because of its lower frequencies but also because of the “geometry of the situation,” that is, the favorable nature of the United Kingdom’s coastal terrain. He did add, though, that he had already ordered four British CHL/GCI radars from Canada—as he indeed had, on pressure from Secretary Stimson. Olmstead was going to replace four of the 268’s in the Canal Zone area with versions modified for better low coverage, presumably SCR-516’s. And in collaboration with the Air and General Staffs he had been working out plans for 50 warning boats such as Ingles had recommended, only to have the Navy come in at the last moment and demand control of the flotilla.109

Meanwhile, the Signal Corps Radar Laboratory was seeking solutions: converting the SCR-268 to the SCR-516; incorporating the superior British PPI cathode-ray tube; including additional antennas and providing different frequencies in the same set in order both to fill gaps and to provide target elevation data. The Air Force continued to press the Secretary of War and the General Staff for British radar. When Watson-Watt reported on the air defenses of the west coast, Secretary Stimson arranged for General Colton to confer with C. D. Howe, the Canadian Minister for Munitions and Supply. Colton sought

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to get 100 CHL/GCI’s as soon as possible. He also wanted four sets for Panama which were CHL’s only, for which Secretary Stimson had taken direct action. The President himself had specified them.110

For Watson-Watt was now shifting his critical talents to the air defenses of Panama. He arrived there on the first of March. He began a report to the War Department a week later by stating that the ground detector system then in operation recorded not more than 15 percent of all flights and that the number on which the evidence could be used operationally was much less.111 On one occasion he had observed that although there were thirteen planes in the air, the operations board in the information center had showed only one. In a C-41 he had flown at various altitudes up to 10,000 feet, only to find on landing that the Aircraft Warning Service had failed to plot any part of his flight. In short, so bad in his opinion was the Aircraft Warning Service in this most vulnerable Zone, upon which the military had been concentrating its best efforts for some time, that he concluded “no measures which are economically possible within the next two years” could provide a ground warning service which would be as much as 80 percent reliable. These were devastating opinions to the Secretary of War, to the General Staff planners, and to the Army Air Forces, which was responsible for coordinating and utilizing the Aircraft Warning Service, as well as to the Signal Corps which developed, procured, and maintained the equipment.

This time the Air Forces rose to the challenge. Maj. Gen. Davenport Johnson, commanding the Sixth Air Force at Albrook Field in the Canal Zone, wrote a defense comparable to Corput’s rebuttal of the west coast report. Watson-Watt had been overcritical, Johnson believed. Many flights were not detected because they were training planes proceeding inland over mountainous terrain, where the pick-up efficiency of the long-wave radars of that day was very low. Along the water approaches to the Canal, efficiency had been computed at 59 percent by comparing Aircraft Warning Service plots with known flights; over land approaches, it was 15 percent. But the “efficiency of the entire system at the present time,” Johnson asserted, “is 52 percent.”

Watson-Watt had stressed the defects without noting that the Americans were well aware of them and were correcting them, Johnson declared, and concluded: “It is an excellent report and of great value to the 6th Air Force. However, it was written as constructive criticism of the system from a short inspection, with no background as to the efforts of the 6th Air Force or higher authority to improve the system. ... In the main, the defects may be charged to shortage of equipment, trained personnel, and transportation.”112

As in January for the west coast, so now in March for the Canal Zone, Watson-Watt urged that the SCR-270’s and 271’s be

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replaced as quickly as possible by Canadian models of the CHL/GCI. He would give first priority, he said, to the XXVI Interceptor Command’s need for a ground-controlled interception system, and second priority to sites on the Caribbean approaches, which he thought virtually undefended. Since the CHL/GCFs were not available at the moment, he granted that the 270’s and 271 ‘s would have to be tolerated in the interim, but in his opinion they were such very poor pieces of equipment that even British operators would be unable to get very good results from them. He doubted if American operators could ever be taught much. Those crews which he had observed had shown so little interest in their work that they had not even taken the trouble to plot permanent echoes, he pointed out. For example, the staff officers of the XXVI Interceptor Command had suspected a large error in the bearing data given by an SCR-270 at Pueblo Nuevo, near the city of Panama, but no one had bothered to make the quick and simple cross-check of comparing indicated bearings with the known bearing of a prominent part of the landscape. These personnel deficiencies should have surprised no one, for with the explosive expansion of the Aircraft Warning Service after 7 December 1941, first the Signal Corps had been raided and drained of its relatively few trained operators and then men had been taken indiscriminately from anywhere.113

Although SCR-268’s, 270’s, and 271’s had been in the Canal Zone for some time, neither the engineers who had made the installations nor the crews who worked the sets wholly understood them. As matters thus stood in March 1942, Panama air defenses were weak. Even a 50-percent-effective detector system left many a loophole, and it was well that no enemy attempted to blast the Canal.

Five days after Watson-Watt’s Panama report, another Washington conference boiled up to discuss the situation. Signal Corps men, Air Forces men, and Britishers once again debated, among other things, the distribution of the 588’s which they anticipated. Watson-Watt had urged four CHL’s and two GCI’s for the Canal Zone at once. That meant SCR-588’s, which the Signal Corps had been seeking to obtain from Research Enterprises Limited since January. None had been delivered. Indeed, Research Enterprises was having some difficulty with its design and production. General Colton wanted some sets to use for training of operators, a reasonable desire in view of the basic deficiency. “I think it is foolish,” he said, “to send equipment without training personnel. It is idiotic.” But he lost his point. Suppose that the Japanese attacked the Canal and that the War Department had no 588’s there, as General Marshall had ordered. Whether there was anyone trained to operate the sets or not, they at least had to be in place. Colonel Marriner said, “We will fix up Panama or else.” Colonel Meade of the Signal Corps agreed. “I have had considerable dealings with the Panama situation,” he said, “and it is my firm opinion that if anybody in this room decides anything is ahead of Panama that person will soon occupy a different position from that which he now holds.”114

General Colton had ordered 100 of the Canadian-manufactured sets. Then, as he

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explained, he had raised the total to 104 because the word had come down from President Roosevelt for the first four to go to Panama. Research Enterprises Limited was just now producing them. CHL’s only, they did not have the height-finding equipment which both the Air Forces and Watson-Watt himself had assumed that they would have. They would not be able to serve as GCI’s, the very application so much emphasized for the west coast and for Panama.

Nor had the combined CHL/GCI yet been perfected. Watson-Watt had asked in January for CHL/GCI’s to replace the 270’s and 271’s on the west coast. Now he was asking for them again, in March, for Panama. If there was any good in this ill wind, it was that it helped to demonstrate to the Air Forces the difficulty in designing and producing intricate apparatus. A Canadian factory producing British equipment was experiencing the usual trouble and delay. A Signal Corps team journeyed posthaste to Toronto and spent three days in ascertaining the facts. One member of the group was John J. Slattery, chief of the Radar Laboratory’s System Engineering Section. After the initial meeting with the Canadians on 14 March, he reported that Research Enterprises Limited admitted that, although a prototype model was well along, there was not any CHL/GCI.115

The Canadian-built SCR-588 thus began as a CHL. The first nine sets were without height-finding characteristics. Production of the CHL/GCI combinations, designated SCR-588-B, began so slowly that by June the Signal Corps had received for the Air Forces only ten 588’s in all. The tenth was the first CHL/GCI to be delivered to the United States.116 Far from replacing at a sweep the American 270 and 271, as Watson-Watt and the American top command had expected, operational 588’s would remain relatively few right through to the end of the war. But the U. S. Army’s original radars, designed by the Signal Corps and built by American industry, would multiply in numbers and in combat applications. The SCR-268, 270, and 271 proved themselves everywhere in the field during this winter and spring of the first year of the war.117

Thus during the first six months of World War II, the Signal Corps struggled to meet its equipment and troop requirements. Its schools, laboratories, and procurement organizations were getting into motion on the scale necessary to supply the unprecedented quantities of men and material which were needed for a global war. Meanwhile, until the flow could increase substantially beyond the first trickles, such signal troops as were already in the field or soon to arrive there had to serve with what little they had or could acquire.