The Cold War: A MILITARY History (18 page)

The first practicable solution was the use of multiple re-entry vehicles (MRVs), in which several RVs were placed on one missile and, like the shot from a hunting gun, were all aimed at the same target, thus increasing the chance of a kill. A variation on this theme was to aim the MRVs at several targets within the same small area, and the three MRVs on the Soviet SS-9 Mod 4, for example, were aimed to impact with the same spatial dispersion as the three silos in a US Minuteman complex.

Technology moved on quickly, and it then became possible to target each warhead independently on to separate targets. This was achieved by mounting them on a post-boost vehicle (PBV, also known as a ‘bus’), which, under computer control, dispatched its RVs one at a time according to the targeting programme. Such warheads were known as ‘multiple independently targeted re-entry vehicles’ (MIRVs), and eventually missiles were carrying as many as fourteen. Unfortunately, radar observation was able to determine how many such devices were being launched by a particular missile bus by counting the number of course alterations (known as ‘dips’), so the RVs were equipped with decoys and ‘penetration aids’ which matched the real RVs’ radar and thermal signature, to confuse the defences.

Single warheads, MRVs and MIRVs all followed ballistic trajectories, which could be rapidly and accurately predicted by the defence, but as the Cold War came to an end a new type of warhead, the Manoeuvrable Re-entry Vehicle (MaRV), was under development, although it did not attain operational status.

THROW WEIGHT

The maximum missile payload was termed the ‘throw weight’, and during the SALT II negotiations this was defined as the sum of the weights of the RVs, the post-boost vehicle and any anti-ballistic-missile penetration aids, including the devices to release the RVs. Throw weight was thus a function of the power of the missile’s propulsion system, and increased steadily over the years. In any one missile the amount of fuel was fixed, so the only way to alter the range was by varying the payload – i.e. by reducing the number of RVs, ‘penaids’ or decoys.

One of the significant elements of throw weight was that it showed the potential for future improvements, since existing throw weight could be fractionated to provide a greater number of smaller warheads, thus increasing the war-fighting capability. As designers became more able to reduce the size of warheads, however, throw weight became less important, and it was in any case never an indication of a system’s ability to destroy targets at the far end of the flight.

ACCURACY

The accuracy of missile RVs is expressed as the circular error probable (CEP), which is defined as the radius of a circle, centred upon the
mean point of impact
, within which 50 per cent of the warheads aimed at the target will fall. The size of the CEP is determined by a combination of computer calculations and empirical data obtained from the testing programme, and is normally understood to apply to the missile’s maximum range. When fired to less than that range, the CEP reduces in proportion.
^fn10

Of greater importance is the distance between the mean point of impact and the target itself, which is termed
bias
. This is similar to the deflection of a rifle bullet by wind, and in the case of a missile is a result of the cumulative effect on the trajectory of the missile and the RV of system errors such as uneven erosion of the ablative shield
^fn11
during re-entry and errors in components such as the on-board accelerometer, as well as unforeseeable events such as the weather over the target.

TIMING

Timing was, for both sides, a critical consideration. In launching a first strike, for example, there was a host of weapons to be co-ordinated, including:

In addition, the USA had to consider:

‘FRATRICIDE’

There were also many technical restrictions. It was discovered in the 1970s, for example, that an attack by several warheads on a single target – or a simultaneous attack on an entire missile field – would inevitably lead to ‘fratricide’, in which the explosion of the first warheads to arrive would either destroy the subsequent warheads or knock them off course. This effectively reduced the number of warheads that could attack any one target to two within a few seconds of each other, followed by a gap of some ten to twenty minutes before a further attack could be undertaken.

fn1
A ballistic missile is one launched by a motor which then cuts off, so that for the rest of the flight the missile follows a trajectory in which the predominant forces are gravity and aerodynamic drag.

fn2
The German Second World War missiles had both a designer’s designation and a
Vergeltungswaffen
(Vengeance Weapon) designation. The V-1 (Fieseler Fi-103). was a pulsejet-powered, winged missile. (Fieseler was a German aircraft design and manufacturing company). The V-2 (Aggregat A-4) was a rocket-powered long-range missile. (All ballistic missiles designed at the Kummersdorf and Peenemünde development centres had an ‘
Aggregat
’ or ‘model’ number, starting with the A-1 in the early 1930s.)

fn3
There was also a third plan, which involved mounting a V-1 missile in a container atop the hull of a diesel-electric submarine, which would surface for the launch. This was the forerunner of the cruise missiles which were operational for a short time in the 1950s and 1960s, and again from the 1980s onwards.

fn4
This explains why Moscow was a ‘withhold’ in most US nuclear plans.

fn5
Extensive research by the author has failed to unearth a single example of a general or admiral proposing that his own service or branch of service should be reduced in size since national defence would be better served by an increase elsewhere.

fn6
Hegel postulated that all progress is the outcome of a conflict of opposites, or that thesis and antithesis interact to produce a synthesis. From this some twentieth century thinkers have suggested that everything is organized in a threefold system: e.g. earth, air, water.

fn7
In
The Third World War; August 1985
, the war depicted by General Sir John Hackett culminates in a single Soviet strike on the British city of Birmingham, to which the USA and the UK immediately respond by launching two missiles each at the city of Minsk.
⁴

fn8
See here
.

fn9
It should be noted, however, that a withhold in a US nuclear plan might not also have been withheld in British, Chinese or French national targeting plans.

fn10
Thus, if a missile with a maximum range of 10,000 km with a CEP of 1 km is fired at a target 8,000 km distant, the CEP will be 1 × (8,000 ÷ 10,000) = 0.8 km. It should be noted, however, that the CEP has always been a fairly uncertain figure, not least because neither the USA nor the USSR was keen to reveal the CEP of its own warheads with too great a degree of precision.

fn11
The ablative shield is designed to ease the RV’s re-entry into the atmosphere and is constructed of materials which are intended to erode.

9

Intercontinental Ballistic Missiles

THE US ICBM PROGRAMME

Snark and Navaho

IN THE IMMEDIATE
post-war years the feeling in the United States was that ballistic missiles offered the best long-term solution for strategic warfare, but that the technology of the time did not appear to make it possible to build a missile with the necessary range (9,300 km) and capable of carrying a nuclear payload, which at that time was large and heavy, weighing some 3 tonnes. The Convair company flight-tested the intercontinental-range MX-774 missile in 1948, but the newly independent US air force decided to follow the path pioneered by the German V-1 ‘flying bomb’ and to develop cruise missiles
^fn1
instead.

The first of these was the N-69 Snark pilotless bomber, which was much larger than the V-1 and had a range of 10,200 km, cruising at a height of some 12,000 m and using a star tracker to update its inertial navigation system. Its speed of 990 km/h meant, however, that, at its extreme range, it took some eleven hours to reach the target. The nose-cone carried a 5 MT (later 20 MT) nuclear warhead, and the missile could approach the target from any direction and at any height, while its very small radar cross-section made it difficult to detect. The Snark entered service in 1957 but was retired in 1961, when the Atlas ballistic missile became operational; its main significance was that it was the first operational missile to bring one superpower within attacking range of the other.

Snark was due to be succeeded by the SM-64A Navaho, a vertically
launched
, winged cruise missile, which travelled at Mach 3.25 (3,500 km/h) at a height of 18,300 m. Navaho would almost certainly have proved a highly effective strategic weapon, but it never reached production, as the USAF had already transferred its attention to ICBMs.
^fn2

Redstone and Jupiter

Development of long-range ballistic missiles in the United States in the immediate post-war years was erratic, to say the least. The US army had obtained the plans for the A-4 (V-2) and assembled a number of former German scientists, including Werner von Braun, at the Redstone Arsenal. Their first product was the Redstone short-range (400 km), land-mobile, liquid-fuelled, nuclear-armed missile, which was in service from 1958 to 1963. Next the army started to develop the Jupiter, which was again a land-mobile missile system, but this time with a range of 2,400 km. This was midway through development when, in late 1956, the secretary of state for defense ordered that the US air force was to assume responsibility for all missiles with a range greater than 200 nautical miles (370 km). Development was completed by the USAF, and Jupiter subsequently saw limited service with the air force.

Thor

Having been concentrating on long-range cruise missiles, the USAF now had to make up for a lot of lost ground. Despite having been handed the perfectly acceptable Jupiter by the army, it initiated a very expensive crash programme for its own IRBM, leading to the Thor. This did nothing that Jupiter could not already do, but operated from a fixed base, rather than from a mobile platform. Thor’s 2,700 km range, however, was insufficient for the missile to be launched against the USSR from the continental USA, so it was handed over to the UK air force, which deployed sixty missiles between 1959 and 1964.

The entire Thor storage-and-launch complex was above ground in unprotected shelters, and the missile had be towed out to the launch pad, raised to the vertical, fuelled, prepared, and then launched, the whole process taking fifteen minutes. This was all done in the open, on concrete hard-standing, at well-documented sites, and was very vulnerable. No cost-effective measure to reduce the reaction time could be found, so the missile was phased out after only five years of service.

Atlas

Meanwhile, the USAF’s major development effort had turned to the Atlas missile, which was much larger and was a true ICBM, with a range of 14,000 km. Atlas benefited from much of the technology which had been developed for the Navaho cruise missile, and entered service in 1960.

The first USAF squadron equipped with the Atlas missile used an almost identical siting system to Thor, with six above-ground shelters and each missile having a thirty-minute launch countdown, but the next squadron’s nine missiles were in three separated groups of three, with individual shelters having a split roof, enabling the missiles to be raised to the vertical
in situ
, thus saving several minutes of launch time. The next three squadrons had similarly dispersed sites, but this time the missiles were housed in semi-hardened bunkers, recessed into the ground and with even greater separation. The final units were housed in hardened underground silos.

Titan

Titan I, which had a range of 10,000 km, was, like the final Atlas, located in silos and raised to the surface for launch; however, it had a new and much faster fuelling system, enabling it to be launched some twenty minutes after the countdown started. There were five Titan I sites, one with eighteen missiles and four with nine each, but the system had only a brief period of service, becoming operational in 1961 and being replaced by Titan II from 1963 onwards, the process being completed in 1966.

Despite its name, Titan II was almost totally different from Titan I, not least because of a 50 per cent increase in range, to 15,000 km. Again, the missiles were sited in squadrons consisting of three widely separated groups of three, with two squadrons at each of three bases, but the new system introduced a completely novel launch system, with the missile being launched from inside the silo. Two other advances in this missile were the use of an inertial guidance system and the use of storable liquid fuel – i.e. the fuel was already loaded in the missile, thus cutting out the time needed to fuel the earlier missiles. In combination these developments resulted in a launch time of just sixty seconds. Fifty-four missiles were deployed, being operational from 1963 to 1987.

Minuteman

By now, the future obviously lay with solid-fuelled missiles, which were safer and more reliable, and in simpler, cheaper and more survivable siting and launch systems. A rail-mobile system was considered for Minuteman I, but the silo option won.

The two-stage Minuteman I was deployed from 1962 onwards in individual unmanned silos, which were scattered over large areas. Ten silos were grouped into a ‘flight’, five flights in a ‘squadron’, and squadrons into
‘wings’
; there were four squadrons in each of four wings, while the fifth wing had five squadrons. The overall total was 800 missiles.