Читать книгу Naval Anti-Aircraft Guns and Gunnery - Norman Friedman - Страница 9
ОглавлениеOne of the more enduring images of Second World War naval warfare is of a ship defending herself against hordes of air attackers. The US Navy, the Royal Navy and the Imperial Japanese Navy found themselves under particularly heavy air attack. This book is the story of how that defence was developed and of how well it worked for the different major navies. Post-war developments indicate the conclusions the major navies drew.
This story would make no sense without taking into account the impact of the Great Depression. For the United States, the Depression began in 1929, and it did not really end until the country mobilised for the Second World War beginning in 1940. Attempts at recovery beginning in 1933 included some new construction, but always under tight economic conditions which limited what else could be bought. That is a major reason why the US Navy was so very under-armed in light anti-aircraft weapons in 1940. The country was fortunate that it could mobilise, even if incompletely, before it had to fight. More money was available before the 1929 Crash, but successive administrations considered military and naval spending a drag on the economy. In retrospect that was no very bad thing, because heavy spending in the 1920s would have produced large quantities of obsolete equipment. Aircraft were changing far too rapidly, particularly in the 1930s.
Rapid pre-war expansion brought its own problems. The navy found itself flooded with new personnel, who had not received extensive training in technical schools before encountering such increasingly sophisticated equipment as the Mk 37 fire-control system. Exercise scores fell, even though targets did not change very much between 1939 and 1941. Again, fortunately for the United States, much of the necessary training was completed by the time war broke out – when even more new sailors arrived.
The situation in the United Kingdom was more complicated. Before the First World War the Royal Navy was clearly the most advanced in the world, and during the war it gained far more experience than its rivals. Despite the crippling cost of the war, it was able to continue development after the war. It also had an enormous overhang of existing modern ships, so new construction was not too urgent during the 1920s. Beginning in 1919, the British adopted the ‘Ten Year Rule’ for planning, the assumption that they would not face a major war for a decade. By 1929 it had been made self-perpetuating. Initially the rule was probably mainly a way of emphasising the need to modernise in view of changed orientation (towards a Japanese threat), but ultimately it became a way to cut expenditures so as to promote economic recovery from the remaining damage done by the First World War. Ultimately the effect of the Rule was to cut expenditures on expendables, such as shells and fuses. Thus, when the situation was reversed and the initial recovery programme concentrated not on ships or guns but mainly on items such as shells and fuel reserves and quartz for sonar transducers.
As in the United States, the effect of the Depression was to limit new production, although work on prototypes continued. Unfortunately the British felt constrained to mobilise much earlier, because the Japanese advance in the Far East threatened them more directly. The ‘Ten Year Rule’ was dropped in 1932, and by 1934 a Cabinet committee originally formed to develop disarmament policy had been transformed into the Defence Requirements Committee (DRC), responsible for making up deficiencies accumulated under the ‘Ten Year Rule’. At about the same time, before Hitler rose to power in Germany, some in Britain saw Europe skidding towards war. That was another reason to repair deficiencies in defence, but it also greatly complicated the British position – the country faced war both in the Far East (which the Royal Navy had long envisaged) and in Europe. The Royal Navy formulated its anti-aircraft rearmament programme in 1936, after the shock of nearly having to go to war with Italy over the Abyssinian (Ethiopian) Crisis.
From an air defence perspective, mobilisation (or rectification of deficiencies, as it was initially) meant that the Royal Navy had to continue to produce existing weapons and fire-control systems, whatever their deficiencies: the iron law of mobilisation is that you produce what is on hand – you do not wait for something better. The Depression compounded the problem by dramatically shrinking the British industrial base. As the country recovered in the mid-1930s, its industrial pattern changed away from what the Admiralty had previously relied upon, so it became more difficult to build back-up. Developing entirely new systems while mass-producing existing ones was less and less possible. That is why the Royal Navy entered the Second World War with totally inadequate high-angle control systems. It had no real alternative. The navy and its ordnance organisation knew what was happening, but that did not really matter.
The Royal Navy’s view of ship design requirements also had a considerable impact. Given the worldwide empire, the Royal Navy always had to take the need for numbers into account. The Admiralty generally equated ship size with cost. Cruisers were a particular problem. In the 1920s the Admiralty estimated that it needed seventy cruisers. It found the new 10,000-ton ‘Treaty Cruisers’ ruinously expensive, and British delegates to the London Naval Conferences of 1929 and 1935 sought to curb the size of foreign cruisers so as to make the desired number of British cruisers affordable. The 1930 London Naval Treaty prohibited further construction of cruisers armed with 8in guns, but at a high price: the Royal Navy had to agree to near-parity with the United States, which did not have a global empire and needed many fewer ships. The British believed that rational foreign navies would be satisfied with cruisers about the size of its Leanders, about 7000 or 8000 tons rather than 10,000 tons. They were shocked when the US and Imperial Japanese Navies both laid down much larger ships. The British felt compelled to build their own large cruisers, the ‘Town’ class – which they could hardly afford in sufficient numbers. They finally solved the problem in the 1936 London Naval Treaty, which limited future cruisers to 8000 tons. Only the British actually built ships of this size, the Fiji class. The US Navy designed an 8000-ton cruiser (CL 55), which led it to design a dual-purpose 6in gun as armament, but once war broke out in 1939 the treaty was considered defunct, and the CL 55 actually ordered was the 10,000-ton Cleveland.
Anti-aircraft guns in action: 4in Mk V HA guns on board the Australian cruiser Sydney. (State Library of Victoria)
All of this had painful implications for the Royal Navy. The Fiji design packed the armament of a 9100-ton ‘Town’ into an 8000-ton hull. The ‘Town’ had a heavy anti-aircraft battery by pre-war standards, but early war experience showed that those standards were grossly inadequate. Unfortunately the ‘Towns’ and other British warships turned out to be too tightly designed to accept much additional light anti-aircraft armament without considerable sacrifices. The British experience contrasts with that of the US Navy, which managed massive increases in light anti-aircraft weapons as the war progressed. It is possible, too, that British standards of stability prohibited anything on the US scale; the Royal Navy often operated in rougher waters.
Money was too short between the wars to replace the obsolete Mk 19. The best that could be done was to combine it and a new stereo rangefinder on a single enclosed mounting, which was called Director Mount Mk I. It was installed during 1939–40 on board US battleships and cruisers. The boxy director mountings are evident fore and aft on board Northampton, photographed in Brisbane between 5 and 10 August 1941. The opportunity was taken not only to integrate rangefinders and directors, but also to move the directors to the centreline, where they had much better arcs (later cruisers had directors on the centreline). Modernisation included doubling the medium-calibre anti-aircraft battery to eight single guns, the number in later cruisers. As early as 1937, the US Navy planned to modernise its newest battleships (the ‘Big Five’) with newer Mk 33 directors, which were considerably better than Director Mount Mk I, but that was not done. (USN courtesy of Edward L O’Neill, 1983)
The medium-calibre long-range anti-aircraft fire-control systems used in the Second World War can all be traced back to those of the inter-war years. Because very little money was available in the 1930s, the key issue was whether earlier, unsatisfactory, systems could be the basis for step-by-step development into something effective. At first glance the US Navy’s Mk 19 director (centre) flanked by two separate ‘altiscopes’ on board the heavy cruiser Chicago looks distinctly unpromising. Operators at the director looked at the target and corrected aim, but because the altiscopes (range- and heightfinders) were physically separate the director operators could never be sure that they and the altiscope operators were even tracking the same target. The connection to fuse-setters at the guns was even more tenuous. However, the tachymetric concept embodied in the director was viable. The next step was to adopt stereo rangefinders which could be installed in an integrated director, effectively combining the altiscope and an evolved Mk 19 as Mk 28 and Mk 33, the main prewar medium-calibre systems. The step beyond, which created the successful wartime Mk 37, was to clear the director by moving the computer below decks, connecting it with the director by synchros and power drives. At the same time the fire-control system was more tightly integrated with the fuse-setter, which ultimately was placed in the ammunition hoist. This photograph was taken at Mare Island in 1931. The hooded object below the anti-aircraft fire control platform was a main-battery director.
The inside of a Director Mount Mk I shows just how simple it was; the object in the foreground is largely unmodified Mk 19 director. This illustration is from the manual, issued in July 1940.
In both the United States and the United Kingdom, the impact of the Depression was to reduce training and to defer desired anti-aircraft upgrades (such as additional guns) and, more subtly but probably more importantly, to defer purchases of expendables, such as ammunition and, crucially for anti-aircraft warfare, fuses. Training time mattered enormously, not only because it determined how well systems would perform in wartime, but also because training exercises were generally the source of the navies’ expectations as to wartime system performance. They shaped what the navies thought they needed. Only at the end of the Second World War did the US Navy form a special dedicated experimental test and evaluation unit. Until then experiments and training were tied together.
For the Royal Navy, the Depression deferred the introduction of radio-controlled drone targets, which would have done a lot to make target shoots more realistic and thus might have goaded the Royal Navy towards developing more effective forms of fire control in time for the Second World War (it is not clear that the US Navy had the potential to adopt target drones much earlier than it did). The Royal Navy used its drones differently from the US Navy, and they could not simulate dive bombing. At the end of the war, the commander of the British Pacific Fleet argued that his fleet’s poor anti-aircraft performance, compared to that of the US Navy, could be traced in part to its lack of realistic anti-aircraft training (the US Navy was plentifully supplied with drones). For both navies, despite clear understanding of the consequences, it was impossible to replace powder time fuses with mechanical ones, given the huge numbers involved. The US Navy had to accept a very high rate of duds and low-order detonations, which may not have been obvious until it began using drones for target practice in 1939. As late as 1941 the Bureau of Ordnance had to warn the fleet that the next year it would have to use powder fuses for half its practice firings.1
The third major naval power, Japan, had yet a different experience. Despite the effect of the Depression, and also despite relative poverty, successive Japanese governments continued to spend heavily on their fleet. They did not spend much on developing entirely new systems, although there were major exceptions such as the ‘Long Lance’ torpedo. In particular Japan could not develop new industries such as electronics to anything like the level of the much wealthier Western powers. In effect Japan mobilised continuously between the World Wars, and it too obeyed the iron law. With important exceptions (mainly naval aviation), the Imperial Japanese Navy of 1941 was a superbly developed First World War navy. Like Britain and the United States, Japan developed radio-controlled target drones.
By 1940, with the world in crisis, the US Navy could deploy the medium-calibre system it would use during the Second World War, albeit as yet without radar. Hillary P Jones is shown on 14 December 1940. British observers were impressed by the all-dual purpose main battery and the Mk 37 fire-control system (as yet they were probably unaware of the integrated fuse-setters in the ammunition hoists). The US system included a stable vertical (a vertical reference used to stabilise the director) and RPC for the 5in guns. The British argued, however, that US destroyers were top-heavy compared to their own ships; the US Navy did not contemplate the sort of rough waters the British expected. Nos 3 and 4 mounts were unshielded in order to save weight. Notably lacking was much of an automatic battery to beat off dive bombers. This ship could accommodate a pair of 0.50-calibre machine guns on the platform below the searchlight aft. In 1940 the US Navy doubted that defence against such attack was really practicable; it expected to rely on barrage fire by medium-calibre guns. By December 1940 the Royal Navy was using such ‘umbrella barrages’ in action.
By 1941 the US Navy wanted splinter protection for all its guns. Gleaves, a sister-ship of Hillary P Jones, is shown after a Boston Navy Yard refit, 18 June 1941. Nos 3 and 4 guns are now half-shielded (they have no roofs); full gunhouses would have added too much weight. Note also the gun tubs, for 0.50-calibre machine guns, around her after stack. She had another pair of gun tubs just forward of her bridge structure on her 01 level. Her after bank of torpedo tubes had been removed as weight compensation. The next step was to replace No 3 5in gun with a pair of twin Bofors, from 1942 onwards.
More generally, aircraft were the exception to the slow development of fleets between the wars. In the 1920s and 1930s they were inexpensive, and the potential for development was huge. Particularly in the United States and in Japan, relatively small investments in naval aircraft development had huge payoffs. From the point of view of naval air defence, that meant huge changes in requirements and the obsolescence of earlier systems. Thus the Royal Navy, which had been quite air-minded and had deployed an advanced high-angle fire-control system in the 1920s, found it difficult to devise an entirely new system capable of keeping up with a rapidly-evolving threat in the 1930s. On the other hand, because the United Kingdom developed a large electronics industry between the wars, it was able to deploy radar in quantity and with high quality. Radar in turn made it possible for the Royal Navy to make up for deficiencies in anti-aircraft gunnery by controlling fighters against enemy bombers. The Imperial Japanese Navy had no such potential, because it had spent most of its money on pre-electronic forms of naval warfare.
The limited cost and rapid development potential of aircraft explain why Germany, which created a large military machine so rapidly, emphasised them both ashore and over the sea. For the Germans aircraft were also attractive because most people saw them as the embodiment of the future. Hitler and his Nazis represented themselves as the future of Germany, and it was natural for them to make the Luftwaffe integral with the Party. To some extent Mussolini had a similar view of aircraft and his air force, although the result was less successful than Hitler’s. German and Italian shore-based aircraft were the key elements of the war the Royal Navy fought in the Mediterranean.
During the Second World War it was not well understood that although aircraft might be plentiful, experienced aircrew were not. Only after the war did it become clear how devastating losses could be, particularly if new aircrew were not being trained rapidly enough. Thus after the successful ‘Turkey Shoot’ which wiped out the Japanese carrier air arm during the battle of the Philippine Sea (June 1944), US naval aircrew were depressed because they had not dealt with most of the Japanese carriers – a view which carried over into the success of the Japanese decoy force (consisting of carriers with few aircraft) at Leyte Gulf (October 1944). The Japanese were particularly affected because they had decided against expanding their aircrew training programme. Although most aircraft were shot down by fighters, guns did their share. In the Japanese case, the loss of aircrew led indirectly to Kamikaze tactics. After the bloodbath in the Solomons in 1942–3, few of the highly-trained pre-war aircrew remained. Their relatively untrained successors performed much more poorly, particularly since they faced more and more formidable defences: better US fighters flown by increasingly experienced pilots and directed by radar, plus much more powerful anti-aircraft batteries with better fire control and proximity fuses. When asked after the war to justify Kamikaze tactics, a senior Japanese officer remarked that few aircraft returned no matter what the tactics; better to adopt tactics which promised to achieve something for the inevitable sacrifice. That was apart from the possibility of greatly multiplying the number of attackers by using all available pilots, including partly-trained ones. Those pilots could not have executed conventional attacks.
Details mattered enormously. Most anti-aircraft guns, down to about 40mm or 37mm, were power-worked. If a ship lost power, they were nearly useless, even if they had alternative manual controls (which could not move them nearly fast enough to track targets). After HMS Prince of Wales lost power due to a very unlucky torpedo hit, her powerful light anti-aircraft battery was suddenly reduced to a single Bofors on her quarterdeck and a few Oerlikons. No wonder her gunnery officer thought that Bofors was worth all her pom-poms; but he did not realise that the only way to wield massive anti-aircraft firepower was to accept power operation. The flaw in the ship’s anti-aircraft armament turned out to be the absence of emergency diesel generators, of the type the US Navy and not the Royal Navy provided.
Similarly, the way in which fire controls and associated equipment was connected to guns mattered. Until the 1930s the Royal Navy relied entirely on step-by-step motors to transmit data, for example from a fire-control computer to a gun mount. These devices are simple and robust, but their action is abrupt, as they click from one setting to the next. The Royal Navy seems to have rejected stabilisation in anti-aircraft systems because that required smooth transmission from a stable element to the guns and directors. By the time the Royal Navy had a smooth enough form of transmission (Magslip), it was too late to reverse the earlier decision, because Britain was mobilising.
Pre-war financial restrictions precluded development of a fire-control system for the 3in/50 gun, which armed the ten Omaha class cruisers and the oldest battleships, among others. At best, these ships could only fire barrages through which, it might be hoped, an attacking aircraft might fly. As war came closer, old destroyers like Overton, shown, were rearmed with six 3in/50s – but they too had no special fire-control systems, and to describe them as anti-aircraft escorts was unfortunate at best. As late as 1943 destroyer escorts armed with 3in guns lacked any fire controls.
Much the same might be said of the British decision not to adopt stereo rangefinders for anti-aircraft fire. Coincidence rangefinders, particularly the horizontal ones used by the Royal Navy, proved ill-adapted to anti-aircraft operation. Rangefinding problems helped convince the British to accept what turned out to be a poor high-angle control system, in which target speed had to be estimated on the basis of perceived target type. Only in 1943, with the evidence of US stereo rangefinding before it, did the Admiralty admit that it should have adopted stereo techniques for air defence.
Technical details have been presented to give a clear idea of what the major navies were doing during the supposedly empty inter-war period to protect themselves against air attack. Although their efforts were not entirely effective, it is clear that they were extensive. Details also make it possible to compare different approaches, particularly those of the Royal Navy and the US Navy, in as objective a way as possible. To the greatest possible extent, this material has been taken from contemporary internal documents rather than from later ones.
For continuity, the story of systems conceived before the war has generally been continued into the Second World War in the inter-war chapters, the wartime chapters concentrating on entirely new wartime developments. Thus in the US case the various Bureau of Ordnance machine gun directors (Mks 44, 45, 49) conceived in 1940 are in the pre-war chapter, but the wartime Mk 51 and its ilk are in the wartime chapter. Similar logic applies to the other navies. Except for the US Navy and the Royal Navy, virtually all wartime equipment was of prewar conception and design.
Sources
This account concentrates on the US Navy and the Royal Navy because they were by far the most advanced exponents of anti-aircraft gunnery between the wars and during the Second World War, and because their post-war work on guns and fire control reflected their extensive wartime experience. Their story can be told almost entirely on the basis of primary documents. The quality and quantity of documentation differs considerably. Much of the US naval ordnance material, including correspondence files and weapon and fire-control handbooks, has survived, though much less has survived of publications explaining how weapons were to be used. Far less of the corresponding Royal Navy material seems to exist, but the annual official publication Progress in Naval Gunnery tells much of the story. Many British handbooks, some with no surviving US equivalents, have also survived. The rough US equivalents to Progress in Naval Gunnery are the more or less annual Bureau of Ordnance Confidential Bulletin and the voluminous annual Reports on Gunnery Exercises. For ships the most important surviving British documents are the Ships’ Covers and constructors’ notebooks. The reader should be aware that constructors showed little interest in weapon development, though Covers do occasionally include relevant material, and they also often reflect shifts in anti-aircraft thinking.
Other major navies seem much less completely documented. French archival documentation has been supplemented by some publications. The French made extensive pre-war efforts to develop anti-aircraft firepower even though they did not have much opportunity to use their systems during the Second World War. To some extent pre-war work was the basis for post-war development. Documents collected or produced by the victorious Western powers after the Second World War provide insight into developments in Germany, Italy and Japan, but information is limited. The account of Soviet developments is based on published Russian-language material, which has, fortunately, become available in quantity with the end of the Cold War.
By the end of the Second World War, the fusion of surface anti-aircraft fire and fighter defence was symbolised by radar picket destroyers like Chevalier, shown off Hampton Roads, newly converted, on 24 May 1945. A tripod radar mast replaced her forward bank of torpedo tubes; the after bank was replaced by additional anti-aircraft guns. The mast carried, top to bottom, a YE aircraft homing beacon, an SP pencil-beam aircraft-tracking and heightfinding radar, an array of enemy radar receiving antennas (on the yardarm), and a TDY jammer (on the lower platform). The fleet had discovered the value of radar picket destroyers stationed well forward of a force in the direction of a likely threat, and at Okinawa it set up fifteen radar picket (RP) stations, each of which was manned by a destroyer and supporting craft, particularly fire support landing craft (LCS). Ships in the anti-submarine and anti-surface screens were also used as radar pickets as the situation demanded. Each picket was to open fire on any unidentified aircraft which came within 12,000 yds. The destroyers were not specially fitted, but they did have fighter controllers on board. They were primarily radar guards to provide the fleet with early warning. Although not primarily fighter directors, they could be assigned to that role. Pickets were placed 75 miles from the centre of the defended area. That made it possible for them to pass control of friendly fighters from one to another, but not close enough for mutual support when attacked. The SP radar on board a specially-converted radar picket fed a more sophisticated combat information centre on board the destroyer. Destroyer radar picket losses off Okinawa were so severe that alternatives were sought for the planned invasion of Japan: either smaller and hence less valuable pickets (converted destroyer escorts) or submarines, which could submerge in the face of the worst threats. Both were in process when the war ended.
