Thursday, March 10, 2016
More Strategic Bombers
Strategic bombers exercised a major influence over the first half of the Cold War, principally because in the 1940s and 1950s they were the only practicable means of delivering the very heavy atomic and hydrogen weapons over intercontinental ranges. Allied to this, bombers had played a major role in the recently concluded Second World War, with the Allied bombing campaigns against Germany and Japan giving the appearance of a war-winning strategy. Indeed, the war had been brought to a close by the two USAAF (United States Army Air Force) B-29 bombers which dropped atomic bombs on Hiroshima and Nagasaki.
There were also bureaucratic reasons for the fierce advocacy of the bomber, however. The US air force finally became independent of the US army in 1947 and was extremely keen to prove itself to be the war-winning arm in the Cold War. In the UK, which found itself facing the reality that it was now only the second most powerful nation in the West, membership of the exclusive ‘nuclear club’ appeared to be the only way to retain superpower status, and, in the short term, bombers were the only feasible way of achieving that. On the Soviet side, the air force realized that it had never produced a bomber force to match those of the USA and UK, and was desperate to rectify this. Thus, from 1945 into the mid-1960s, the strategic bomber armed with nuclear weapons was the symbol of global power.
Atomic warfare was associated with aviation from the very beginning. The first and last nuclear weapons ever used in anger were dropped by U. S. B-29 bombers in August 1945 on the Japanese cities of Hiroshima and Nagasaki. These actions represented the end of World War II (Japan soon surrendered) and the beginning of the Cold War (erstwhile allies aligned against one another). As postwar tensions mounted, the United States clung to its monopoly on atomic weapons as its trump card in any future conflict. In the late 1940s and early 1950s, the U. S. Air Force developed the newly created Strategic Air Command into an elite force of medium- and long-range bombers capable of delivering nuclear weapons to targets throughout the Soviet Union, a strategy of massive retaliation in the event of war with the communist nation. Though the Soviet Union tested its first atomic bomb in 1949-years earlier than expected-the United States remained well ahead in its capacity for nuclear attack throughout the 1950s. In the early 1950s, the superpowers added thermonuclear weapons to their arsenals; some explosive yields were 1,000 times more powerful than early atomic bombs. By the mid-1950s, it had become possible to kill an entire nation in a matter of days. U. S. military planners hoped their nuclear superiority would deter any war, but should it come they continued to believe they could “win” a nuclear exchange by undertaking a massive first strike, thereby preventing Soviet retaliation.
The study of German jet engines helped the Soviets develop their first jet fighters (in 1946, the MiG-9 and Yak-15 were introduced). At the same time, Soviet designers benefited from the wartime acquisition of several U. S. B-29 bombers. The strategic bomber force was reorganized in 1946 within the Soviet Air Force, equipped with Tu-4 heavy bombers (based on the B-29 design) and Il-28 medium bombers.
The progress of the Cold War since the 1960s, the development of nuclear, thermonuclear, and missile weaponry, as well as the development of entirely new technologies, prompted significant changes in the Soviet Air Force. The political and military leadership needed a world-class airpower to back up rising global ambitions and be able to participate in any number of contingencies-nuclear and conventional. At the same time, the greater emphasis on ICBMs in the development of strategic power allowed the Soviets to reduce a number of obsolete aircraft without lowering the combat capability of its air force.
From the 1960 to the 1980s, the Soviets modernized their fleet of strategic bombers and introduced the supersonic Tu-22 bomber (1963). Beginning in 1987, the Tu-160 strategic bomber entered service. This bomber force was an integral (although the smallest) part of the Soviet strategic triad. Additionally, air-to-surface cruise missiles enhanced the strategic function of these aircraft. The cruise missiles, as well as the introduction of the Tu-26 longer-range bomber, in 1974 gave the Soviet Air Force the ability to carry out deep strikes across Western Europe, the North Atlantic, and North America.
Bomber designers and the tacticians fought an unending war against the potential defenders in an effort to ensure that the bomber would get through to its targets. In the late 1940s the major threat came from radar-directed anti-aircraft guns, which had reached a considerable degree of sophistication, and the bombers’ first response was simply to fly higher than the effective ceiling of the guns. The next threat was air-defence fighters, and here again the bombers responded by flying higher and faster – there were numerous reports of British and US reconnaissance flights over the USSR in the early 1950s in which the Soviet fighters simply could not reach the same altitude as the intruder.
Second World War bombers were fitted with machine-guns in a variety of positions – including the nose, the waist, above and below the fuselage, and the tail – but these were rapidly reduced to just the tail, the elimination of the others saving considerable weight and enabling the aircraft to fly higher and faster. Also in the Second World War, bombers had been escorted by fighters, particularly on the USAAF’s daylight raids; but the strategic ranges now being flown were far in excess of anything a fighter could undertake. So in the 1950s the US air force trialled the idea of the B-36 bomber taking a fighter with it, with the latter being carried on a retractable cradle from which it could be launched in mid-air to deal with enemy fighters, then being recovered for the return to base. A special miniature fighter, the McDonnell XF-85 Goblin, was tested, as was the RF-84K, a modified version of the full-size F-84 Thunderjet fighter, but, although launching proved feasible, recovery did not, and the idea was not pursued.
Electronic countermeasures (ECM) were always used, becoming increasingly sophisticated as time passed. Thus electronic jamming was used to confuse enemy radars, as was ‘chaff’ (strips of metal foil cut to the wavelength of the radar), which was dropped in large quantities, either by the bomber or by specialized escorting aircraft.
One of the earliest devices to help the bomber get through was the US air force’s ADM-20 Quail, which resembled a miniature unmanned aircraft and was dropped over enemy territory, where it flew for some 400 km, using its on-board ECM devices to confuse the enemy as to the strength, direction and probable targets of the incoming bomber force. A maximum of three Quails could be carried by a B-52, and the device was in service from 1962 to 1979.
The main emphasis then turned to stand-off missiles – a concept which, like so many others, had its genesis in Germany, where V-1 missiles had been launched from Heinkel He-111 bombers in 1944–5. The Cold War missiles carried a nuclear warhead and were designed to be launched from the bomber while still outside the range of the enemy air defences. One of the first was the US Hound Dog – a slim missile with small delta wings, and powered by a turbojet – which entered service in 1961. Two Hound Dogs, each with a 1 MT nuclear warhead, were carried beneath the wings of a B-52. The missile could be set to fly at any height between about 50 m and 16,000 m, and had a range at high level of 1,140 km, less at low level. The guidance system was capable of high- or low-level approach, with dog-legs and jinxes to confuse the defence.
Next came the unhappy saga of Skybolt, which was an attempt to use a bomber to launch a ballistic missile, which would have given longer range and, of greater importance, a much shorter flight time. The UK air force joined the project, but the incoming Kennedy administration unilaterally cancelled it in December 1961 – greatly to the indignation of the British, who used the issue as a lever to obtain Polaris missiles and SSBN technology to replace its V-force bombers.
The Short-Range Attack Missile (SRAM), which entered service in 1972, was a rocket-propelled missile with a 170 kT nuclear warhead and a speed of Mach 3. SRAMs could fly either a semi-ballistic, a terrain-following or an ‘under-the-radar’ flight profile, the latter terminating in a pull-up and high-angle dive on to the target. The range depended on the height, and was from 56 km at low level to 170 km at high level. B-52s normally carried twenty SRAMs, while the FB-111A carried six and the B-1B twenty-four.
The Air-Launched Cruise Missile (ALCM) entered service with the US air force in 1982. This weapon had folding wings which extended when it was dropped from the carrier aircraft, and was powered by a small turbojet engine. Designed exclusively for low-level flight, the ALCM used a radar altimeter to maintain height and a map-matching process known as terrain comparison (TerCom) to give very precise navigation. The nuclear-armed version (AGM-96B) had a 200 kT warhead, a CEP of 30 m and a range of some 2,500 km. The AGM-96C was conventionally armed, with a high-explosive warhead, and this version demonstrated its effectiveness and accuracy when thirty-five were launched by B-52s during the Gulf War. B-52s could carry up to twelve and B-1Bs twenty-four.
Soviet stand-off missile development followed a similar pattern and time-scale, although in the early stages of the Cold War the missiles tended to be much larger and less effective than their US counterparts. Indeed, the first missile designed for use by strategic bombers, the AS-3 (NATO = ‘Kangaroo’) remains the largest air-launched missile to go into service, with a length of some 15 m, a wingspan of 9 m and a weight of 11,000 kg; only one could be carried by a Tu-95 (Bear-B). It did, however, have a useful range (650 km) and a high speed (Mach 2), and with an 800 kT warhead it was targeted against large area targets such as cities and ports.
The AS-15 (NATO = ‘Kent’) was much smaller and generally similar in size, performance and role to the US Tomahawk; sixteen could be carried by the Tu-95 Bear-B and twelve by the Tu-160 Blackjack. It carried a 200 kT nuclear warhead and flew at high subsonic speeds over a range of some 3,000 km at a height of 200 m, with an accuracy (CEP) of 150 m.
The most dramatic bomber to serve with SAC was the tailless, delta-winged Convair B-58, with a Mach 2 speed and 8,250 km range. Air-to-air refuelling enabled the B-58 to undertake long flights (e.g. from Tokyo to London), loudly advertising its wartime capabilities. The aircraft used a unique system in which a large pod under the fuselage housed both the nuclear weapon and the fuel for the outward flight; it was dropped complete, enabling the aircraft to make a very rapid getaway before returning to base on its internal fuel supply. Although generally successful, the B-58 was very expensive to operate, even by US standards, and was retired after just ten years’ service, without replacement.
In 1969 US satellites began to return photographs of a new Soviet bomber on the apron at the new aircraft factory at Kazan. This turned out to be a swing-wing version of the Tupolev Tu-22, designated Tu-22M (NATO = ‘Backfire’). Subsequently, a virtually new aircraft with some external similarities to the Tu-22M appeared and was put into production as the Tu-26 (NATO = ‘Backfire-B’). (The relationship between the Tu-22M and the Tu-26 was probably similar to that between the American B-1A and B-1B.)
Three versions of the Tu-26 entered service, one of which carried nuclear weapons for use in the land-attack role. There were, however, repeated arguments between the United States and the Soviet Union over the role of this bomber, with the former stating and the latter denying that it was a strategic bomber. This became a major issue in the SALT II negotiations, and President Brezhnev eventually ordered that the aircraft’s flight-refuelling probes be removed to prove that it did not have the ability to reach the USA, although since these could have been replaced in less than thirty minutes this was only a token gesture. The Tu-26 entered service in the mid-1970s and was produced at the rate agreed under SALT II – thirty per year – with service numbers peaking at about 220.