The US Nuclear Arsenal: Pershing II vs. Pioneer and the Final Missile Duel
Pershing II design and fuel
MGM-31B Pershing II — a two-stage solid-fuel medium-range ballistic missile (MRBM) developed in the second half of the 1970s by Martin MariettaThe launch weight was 16,451 pounds (7462 kg), the length was 10,61 m, and the hull diameter was about 1,02 m.
The engines for the first Pershing were created by the company ThiokolThe fuel chosen by its engineers was one of the most advanced of the early 1960s—a composite class 1.3 (PBAA/AP/Al) with a specific impulse of 260 seconds, high even by today's standards.
The second Pershing was equipped with the company's engines HerculesTo meet the Department of Defense's requirement for more than doubling the range, its engineers took a risk and used a more calorific Class 1.1 propellant (HTPB/AP/Al). It is "doped" with explosives, hexogen (RDX) or octogen (HMX), which allows for a specific impulse of 275 seconds or more.
It should be clarified here that ballistic missiles use two classes of solid propellant: 1.1 and 1.3. The energy content (calorific value) of class 1.1 propellant is 15–20% higher than that of class 1.3 propellant, so for a given launch and throw weight, the former has a greater launch range. Class 1.1 propellant also has superior technological properties: increased mechanical strength, resistance to cracking, and resistance to internal imperfections.
However, the classification 1.1 and 1.3 itself primarily reflects sensitivity to explosion: fuel of class 1.1 is less susceptible to accidental ignition, but when detonated, it behaves like a normal high explosive. It was precisely this increased risk of detonation that prompted the Hercules engineers to take the next step. With the new high-calorific fuel and a launch weight increased by approximately 60% (relative to the Pershing 1A), the maximum range of the MGM-31B Pershing II increased to 1770 km. This is the limit even for modern solid propellants.
Pershing II on the launcher
Controlled warhead and accuracy
The Pershing II is the world's first production missile to be fielded with a MARV hypersonic guided reentry vehicle (GRV) and a RADAG active radar seeker. The GRV, with its W85 nuclear warhead, weighs 677,3 kg. During the terminal phase of its trajectory, it performs controlled pitch and yaw maneuvers, combining the radar image of the underlying terrain stored in the onboard computer with the actual image from the seeker.
Thanks to this, the CEP is reduced from 400 meters (inertial system only) to 30 meters. Externally, the UBB is very similar to the modern C-HGB (Common Hypersonic Glide Body) of the LRHW (Long Range Hypersonic Weapon) missile. Essentially, the Pershing's hypersonic maneuvering warhead is what would be called hypersonic today. weapons.
By comparison, in the USSR, the Yuzhnoye Design Bureau was developing a similar maneuvering UBB for the R-36M missile. Flight tests of the UBB 15F678 were conducted from July 1978 to August 1980, but the project was not finalized. The results were unsatisfactory, and the work was discontinued.
The Pershing II design initially allowed for launches at shorter ranges—in a reduced configuration, without one of the stages:
- MGM-31C Pershing 1B variant (first stage only) - launch weight 5480 kg, thrust 172,00 kN, range 800 km;
- MGM-31D Pershing 1C variant (second stage only) - launch weight 3950 kg, thrust 122,00 kN, range 500 km.
A Pershing 1B during development testing, January 1986.
The most famous photograph of the Pershing II, circulating online and in print media, actually depicts a battery of deployed, ready-to-launch Pershing 1B missiles—the single-stage, short-range variant. Attentive viewers will notice this by the shortened body: the single-stage variant lacks a second stage. Besides Germany, the Israelis also attempted to purchase the MGM-31C Pershing 1B—naturally, the conventional variant—but were categorically refused by the Americans.
The minimum flight time is 7 minutes, with a speed at the end of the active phase of the trajectory (AUP) of 2 km/s. The maximum flight time (1770 km) is 13 minutes, with a speed at the end of the AUP of 4 km/s.
The flight trajectory of the American solid-fuel, two-stage, medium-range ballistic missile Pershing II
The Soviet response: the RSD-10 Pioneer
In 1976, the USSR began deploying the latest medium-range RSD-10 Pioneer (SS-20 Saber) missiles to replace the aging R-12 (SS-4) and R-14 (SS-5) missiles, with two new missiles replacing three older ones. The new, mobile, solid-fuel missile significantly outperformed its predecessors in range, accuracy, reliability, response and reload time, and survivability. It was the first Soviet non-strategic system with multiple independently targetable reentry vehicles (MIRVs).
Full-scale deployment of the RSD-10 missiles concluded in 1986, when the number of launchers reached 441. Two-thirds of these were located in the European part of the USSR and could strike targets in Europe and the Middle East; the rest were stationed in Asia and could reach Alaska.
In the late 1970s and early 1980s, the Western European press experienced "shock and awe": newspapers and magazines vied with each other to publish articles about the "missile threat from the Soviet SS-20." From 1976 to 1986, the Votkinsk plant produced 715 15Zh45 and 15Zh53 missiles in launch containers, an average of about 78 missiles per year (52 for launchers and 26 backups). By comparison, it would be extremely difficult to replicate such a rate of high-tech production in modern Russian industry.
It is understandable that the US became concerned: a serious missile threat loomed over its European allies and US military bases in Europe, which could not be compensated for by any deck aviation 2th and 6th fleets, nor the 150 FB-111A and F-111A/G bombers based in the UK. By the late 1970s, they needed to develop a medium-range counter-missile capability in Europe to at least partially counterbalance the Soviet missile threat.
The RSD-10 Pioneer (SS-20 Saber) was developed by the Moscow Institute of Thermal Engineering (MIT), with A.D. Nadiradze serving as chief designer. It was based on the experience and developments of the Temp-2S (SS-X-16) mobile ground-launched missile system: the 15Zh45 missile was based on the first and second stages of the Temp-2S solid-fuel ICBM. The R&D project for the system was designated 15K645 Pioneer, and work began in 1971.
The system was accepted into service by the USSR Council of Ministers Resolution No. 177-67 of March 11, 1976. On August 30, 1976, the first missile regiment entered combat duty as part of the 33rd Guards Missile Division (396th Missile Regiment, Belarus, Petrikov Missile Base).
A column of mobile ground-based missile systems RSD-10 "Pioneer" (NATO classification - SS-20)
US intelligence estimates
The SALT I Treaty prohibited encryption of test launch telemetry—precisely to facilitate the flow of information to both sides. The Americans, in turn, also agreed not to encrypt telemetry and to camouflage the launch sites of missiles and the impact sites of warheads at test ranges.
Based on intelligence, satellite imagery, and intercepted telemetry, the CIA estimated the missile's range at 2750 miles (4400 km), while US military intelligence estimated it at 3100 miles (5000 km). The total throw-weight was 1740 kg for the 15Zh45 and 1600 kg for the improved 15Zh53.
Servicing the 15F452 warhead for the Pioneer missile system
The 15F452 warhead was cone-shaped, approximately 64 cm in diameter at the base and 1,6 m in height. Each warhead weighed 290 kg. It was designed to equip the MIRVs of the 15Zh45 Pioneer and 15Zh53 Pioneer-UTTKh missiles. The AA-74 warhead was developed by VNIITF.
Estimates of the charge's power differ: 250 kt - according to Baker, op. cit., General Dynamics Missile Systems; 150 kt - by Collins and Victory, US/Soviet Military Balance 1988It was this last figure that became ingrained in the public consciousness for almost 40 years. However, according to information from the Sarov Nuclear Weapons Museum (Arzamas-16), the yield of the AA-74 nuclear warhead was 400 kt (this figure is indicated on the 15F452 warhead data plate). It was with the AA-74/15F452 warhead of the RSD-10 complex that Soviet nuclear physicists from VNIIEF and VNIITF first surpassed their opponents from Los Alamos and Livermore in the specific yield of their warheads.
In the CIA's annual reports for 1977, 1978, and 1979, the SS-20 missile's average CEP was estimated at 300 meters, which, according to military intelligence estimates, was eight times more accurate than the R-12 (SS-4). In an interview with a Defense Department representative on July 3, 1984, the following reliability factors were cited: launcher - 95%, missile in flight - 97%, warhead - 97%, resulting in an overall system reliability of 89%. (Jack Anderson. War Game Gives a New Look at Soviet Missiles // Washington Post. 1984. July 3).
These are mind-boggling figures even by today's standards. The missile made a strong impression on the Western, primarily American, military-scientific community, and now the US urgently needed to catch up.
Special transport containers for Pershing II ballistic missile stages
Changing Pershing II Requirements
Between 1976 and 1978, as data on the SS-20's actual range became available, it became clear that the Pershing II's design specifications did not "reach" the basing areas of Soviet missiles. According to US military intelligence, the first SS-20 Mod 1 (15Zh45) variant with a MIRV had a maximum range of 2750 miles (4400 km). Therefore, the Department of Defense's requirements for the Pershing II were gradually increased: the range was first increased to 900 miles (1400 km), and then to 1100 miles (1770 km), so that the missile could hit targets in the eastern Ukrainian, Belarusian, and Lithuanian SSRs.
Pershing deployment in Europe
The Pershing operational-tactical missile was deployed from 1962 to 1986 as part of three American battalions (divisions) of the 56th artillery Group (later reorganized into the 56th Field Artillery Brigade) in Germany, as well as two air wings of the West German Air Force (Luftwaffe) operating the Pershing 1A. Each battalion or air wing had 36 mobile launchers.
The German constitution prohibited the possession of nuclear weapons, so control of the warheads remained in the hands of the US Army. During peacetime, some Pershing-1A missiles were on quick-reaction alert (QRA) duty, while others were undergoing field testing or were kept in barracks awaiting combat alert.
The system was designed to be highly mobile, allowing it to be moved to secret locations in the event of an alert or war. It was to be deployed more than 100 km from the front lines or state borders. Due to its mobility and evasive capability, the Pershing was considered one of the most survivable tactical nuclear weapons ever deployed in Europe.
According to the Supreme Allied Commander Europe's plan, the primary mission was carried out in one of two modes: peacetime or at a heightened state of readiness (the so-called period of tension). Under the rapid response mode, each battalion or air wing was required to maintain one fire battery (or part of one) in a permanent position to cover designated targets.
Initially, the system was simply called "Pershing," but in 1965, with the introduction of the improved Pershing 1A model, the original modification was renamed the Pershing 1. Military and other documentation used Arabic and Roman numerals, as well as capital letters, hence the inconsistency in designations: I, 1, 1a, 1A, 2, II, etc. MGM-31A is the designation of the missile itself; the same missile was used in both the Pershing 1 and Pershing 1A systems.
An American Pershing II medium-range ballistic missile launcher. The towing vehicle is a MAN M1001. This photograph captures the missiles' dismantling process in accordance with the INF Treaty, signed in 1987.
The nuclear warhead of the first Pershing: a W50 charge
All modifications of the first Pershing were equipped with a nuclear warhead with one of the most advanced, if not the most advanced, nuclear payload in the American arsenal - W50.
The W50 charge was a two-stage gas-boosted thermonuclear design with an external neutron generator. The case diameter was 14 inches (360 mm), with a mounting flange diameter of 15⅜ inches (390 mm); it was 44 inches (1100 mm) long and weighed 412 pounds (187 kg). The aluminum alloy mounting flange fit tightly against the steel cylindrical case. The capsule containing the gaseous deuterium-tritium mixture was mounted outside the sealed lid so that it could be replaced without compromising the charge's seal. The system contained two neutron generators.
A total of three variants were developed and mass-produced—the W50Y1, W50Y2, and W50Y3—with yields of 60, 200, and 400 kt (250, 840, and 1670 TJ), respectively. According to some sources, the yields of the W50Y1 and W50Y3 were 40 and 440 kt (170 and 1840 TJ). The 200 kt warhead was intended for the Nike Zeus SAM, but until 1991 it was used only on the Pershing 1A.
The W50 warhead had no modern detonation protection systems, no insensitive explosives, and no Category A deployment control system. After launch, the W50Y1/2/3 nuclear warhead's inertial fuse was powered by the second stage's power supply, and after its separation, its own warhead battery was activated. If the missile was on course and the second stage separated within 300 milliseconds of engine shutdown, the thermal battery excitation circuit was activated. The thermal battery was triggered immediately before atmospheric entry, and at a deceleration of 0,5 g (negative acceleration of 4,9 m/s²), the radio fuse was activated and the warhead was armed.
In the 400-pound weight class, the W50 YAZU had no equivalent in the American arsenal until the three-stage W88 appeared in 1989.
According to researcher Chuck Hansen, the W50 secondary warhead was also used in the W78 warhead of the Minuteman III missile. The W78's yield is estimated at 335–350 kt (1400–1460 terajoules), while the secondary warhead's yield, according to Hansen, is 150 kt. The Minuteman III remains in service (currently under the control of the US Air Force Global Strike Command).
With a specific yield of 2,14 kt/kg net weight, the W50 was one of the most advanced charges in the American arsenal.
A strange decision: replacing the W50 with the W85 and W86
In the company 1973 Martin Marietta began developing a medium-range missile system to replace the Pershing 1A on its own initiative and at its own expense. A contract with the Ministry of Defense was signed in 1975.
During the R&D process to convert the Pershing from a tactical ballistic missile to an IRBM, between 1976 and 1978, a strange event occurred: who made this decision and at what stage is unknown. The W50 warhead was replaced with two new, lower-yield warheads: the W85 and the penetrating W86. Wikipedia and other American sources explain the rationale:
400 kt is too much for the tactical role of a Quick Reaction Alert (QRA) system.
From an engineering point of view, this solution looks questionable. Perhaps 400 kt is indeed too much for the tactical missile role, but for an IRBM, it's just right: a longer-range missile is designed to hit more hardened strategic targets deep in the interior, which is precisely where a powerful warhead is needed. Soviet designers took a different approach: between 1962 and 1978, the warhead yield of the R-17 Elbrus tactical missile, on the contrary, increased 50-fold, from 10 to 500 kt.
The CIA and US military intelligence first "saw" the new Soviet SS-20 on satellite imagery on September 21, 1974, at the Kapustin Yar test site. Initially, the CIA logically assumed that the USSR would deploy the new missiles in roughly equal numbers, in mobile (PGRK) and fixed (in 8P763 Dvina silos from the decommissioned R-12) variants.
The principle of mixed basing was not foreign to the USSR, and it was later actually implemented, but on a different missile. In the late 1980s, the Strategic Missile Forces adopted the 5th-generation solid-fuel SS-24 Mod 3 and Mod 2 Scalpel (RT-23 UTTKh) ICBMs: a fixed version with 15P760 silos (60 missiles) and a mobile 15P961 rail-mobile missile system (BZhRK) with 15Zh61 missiles (36 missiles). The Americans themselves planned to follow suit: in the fall of 1983, General Scowcroft's commission recommended deploying the latest MX ICBMs, 50 missiles in hardened silos from the Minuteman III (400th Squadron) and another 50 on the BZhRK. However, the end of the Cold War thwarted these plans. However, the mixed scheme was never applied to the SS-20, but more on that below.
Soviet inspectors and American escorts at the Pueblo Test Site in Colorado, USA, in 1989.
Pershing II targets in the USSR
Obviously, typical targets for the Pershing II were to be IRBM and ICBM silos, underground command posts, and deployment areas for mobile missile systems—PGRK and BZhRK.
Within the missile's range were IRBM and ICBM silos, IRBM and ICBM mobile ground-launched missile systems, and rail-mobile missile systems deployed in the western USSR. The 43rd Missile Army's launch sites were also under attack.
At the time of the collapse of the USSR, the 43rd Missile Army included seven missile divisions:
- 19th Missile Division - Rakovo, Khmelnytsky region;
- 32nd Missile Division - Postavy, Vitebsk region;
- 33rd Guards Missile Division - Mozyr, Gomel Region;
- 37th Guards Missile Division - Lutsk, Volyn region;
- 43rd Guards Missile Division - Romny, Sumy Oblast;
- 46th Missile Division - Pervomaysk, Nikolaev region;
- 49th Guards Missile Division – Lida, Grodno Region.
Some divisions were armed with silo-based or mobile ICBMs, while others were equipped with R-12, R-14, and RSD-10 Pioneer MRBMs. Between 1975 and 1977, the 33rd Missile Division began rearming its fixed R-12 and R-14 missiles with mobile RSD-10 Pioneer missiles.
From this perspective, the decision to replace the W50 with two warheads—the W85 for the "classic" warhead and the W86 for the "penetrating" warhead—seems logical. However, as experience has shown, the USSR never even considered deploying the newest SS-20s in the old R-12 silos—only the PGRK variant.
W86 penetrating charge
W86 — a nuclear warhead for the penetrating warhead ("bunker buster") of the Pershing II missile. Work on the program was halted in September 1980, when US intelligence agencies finally realized that the SS-20 would not be deployed in fixed silos, and the Pershing II's mission shifted entirely from destroying underground hardened targets to engaging soft targets on the surface and at greater range. The W85 warhead, which was being developed in parallel, was ultimately used in all production Pershing IIs.
The penetrating warhead casing for the W86 was first developed in 1975 at the National Laboratory Sandia, which specialized in adapting Los Alamos and Livermore lab charges to specific delivery vehicles. The weapons were designed to destroy hardened underground targets (silos, command posts) and create craters on runways.
The W86 is based, virtually unchanged, on the W74 charge, developed for the 155mm nuclear artillery shell (XM517) at the Los Alamos National Laboratory. The W74 was a rather primitive "gun-type" design and contained 12 cylindrical pellets of subcritical uranium metal, highly enriched in the U-235 isotope (95% enrichment), with a total weight of 100 pounds (45 kg).
The W86 nuclear warhead, designed for use with the Pershing II missile.
A 2005 study by the US National Research Council examined several proposals for nuclear weapons capable of penetrating reinforced concrete and penetrating deep into the ground. It noted that the diameter of the W86 warhead is only 170 mm (6,7 inches), and the loaded warhead weighs 184 kg (406 pounds). According to the laboratory's calculations, Sandia, such a warhead could penetrate 7,2 m (24 ft) into medium-density soil, 18,7 m (61 ft) into soft soil, and 115 m (377 ft) into seabed muddy soil (primarily clay), with a peak permissible deceleration of 10,000 g (98,000 m/s²). These figures are taken from a classified report Sandia on the development of a penetrating warhead for the W86 charge.
The study indicated that the "low-yield weapon" (W86) had an energy release of less than 5 kt (21 TJ), and according to other estimates by independent researchers (FAS) - up to 10 kt (42 TJ); this is exactly the power of the W74 charge.
A 1979 article in a trade journal Sandia Lab News describes the penetrating warhead as a 400-pound (approximately 180 kg) projectile penetrating 67,5 feet (20,6 m) into the salt lake bed at the Tonopah Test Range at a surface impact velocity of 1796 feet per second (547 m/s). This is approximately the velocity of a Pershing II warhead at the terminal phase of its trajectory. Approximately 20 tests in soils of varying densities were required to refine the design.
The W85 nuclear weapon, which became the sole combat equipment of the Pershing II warhead
The W85 is the Pershing II's only payload.
W85 — a thermonuclear nuclear warhead developed by the Los Alamos National Laboratory for the MGM-31B Pershing II missile warhead. It is a charge with a variable energy release rate of 0,3, 5, 10, and up to 80 kt (1, 21, 42, and up to 335 terajoules), created on the basis of the W61 Mod 4 device. The warhead of the Pershing II weighed 591 pounds (268 kg), including the automatic control unit and the warhead body.
A total of 215 W85 warheads were fired. After the INF Treaty came into force, all of them were repackaged by the laboratory. Sandia into the bodies of B61-10 aerial bombs. Today, they are stored in US Department of Defense warehouses: not a single one has been dismantled or disposed of – all are carefully stored.
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