W49

Last updated
W49 warhead
Mark 49 warhead.jpg
The W49 warhead
Type Nuclear weapon
Service history
In service1958 to 1965
Used byUnited States
Production history
DesignerLos Alamos National Laboratory
Variants7
Specifications
Mass1,640 pounds (740 kg)
Detonation
mechanism
Contact, airburst
Blast yieldY1: 1.1 megatonnes of TNT (4.6 PJ)
Y2: 1.45 megatonnes of TNT (6.1 PJ)

The W49 was an American thermonuclear warhead, used on the Thor, Atlas, Jupiter, and Titan I ballistic missile systems. W49 warheads were manufactured starting in 1958 and were in service until 1965, with a few warheads being retained until 1975.

Contents

The weapon itself was a Mark 28 Y1 warhead modified for the missile role.

History

Initial development of the Mod 0 warhead

Development began in mid-1956 with the need for a warhead for the then in development Thor, Atlas, Jupiter and Titan missiles. This led to work being performed to develop the XW-35 and XW-35-X1 warheads, with the high-yield, improved X1 to enter service approximately one year after the XW-35. However, development of these missiles was delayed and it became apparent to designers that the planned service entry date for the XW-35-X1 would now be the same as the missiles (except for Jupiter), leading to the cancellation of the XW-35 and the decision to fit XW-28 warheads to Jupiter as an interim warhead until the XW-35-X1 entered service. [1]

In December 1957, the stockpile entry date for the XW-35-X1 slipped, leading to the decision to also fit Atlas, Titan and Thor with the interim warhead, now called the XW49. The warhead was a Mark 28Y1 warhead which was converted by removing internal power as this would be supplied by the warhead adaption kit. It was felt that this warhead would be available by 1958. The design was sealed and pressurized, and no component replacement would be permitted in the field; the warhead only needing periodic electrical and pressure testing. [2]

The Mark 49 Y1 Mod 0 was designed released in March 1958 and entered the stockpile in September 1958. For still classified reasons, the WX-35-X1 was cancelled in June or July of that year. [3] [4]

The Mark 49 Y1 Mod 0 was 20 inches (510 mm) in diameter and 54.2 inches (1,380 mm) in length. The warhead only needed pressure testing at 30 day intervals and electrical testing after mating the warhead to the reentry vehicle. The warhead was the first to use a rotary chopper inverter/converter to convert the 28 volts DC supplied to the weapon to 2200 volts DC for the X-unit's capacitor bank. The warhead had both air-burst and contact-burst fuzing options, and the boosting gas system was mounted inside the pressurized portion of the warhead. [3]

The Mark 49 Y2 Mod 0 warhead was design released in July 1959. [5]

Mod 1, 2 and 3 warheads

The Mark 49 Mod 1 warhead was only different from the Mod 0 in that it incorporated an inertial environmental sensing device that would prevent arming of the warhead until it sensed a reentry environment. This modification was made due to concerns about accidental detonation caused by electrical or procedural malfunctions and errors, and the risk of sabotage. The request for this modification was approved in October 1958. The modification asked that the sensor be actuated as late as possible in flight and that it be located in the warhead in such a way that access to the device would be difficult and time consuming, as to prevent sabotage. Design release for both the Y1 and Y2 warheads was made in June 1959 and was retrofitted to Mod 0 warheads starting in October 1959. [5]

The Mark 49 Mod 2 warhead was cancelled partway into its development. W49 Mods 0 through 2 were internally initiated weapons but at this time it was decided that future warheads would be externally initiated. The Mod 2 requirement was replaced by the Mod 4. [6]

A decision was made in November 1959 that reactor products needed to be conserved. [6] Internal initiation, using a modulated neutron initiator, required Polonium-210 (210
Po), a highly radioactive element. With its short half-life of 138.376 days, 210
Po initiators required regular replacement and a steady stream of reactor-made 210
Po. [7] [8] The alternative is external initiation, using a pulsed neutron generator containing a mixture of deuterium and tritium gas. The device is a small particle accelerator that fuses deuterium and tritium ions together to produce neutrons when electricity is supplied to the device. [9]

Mark 49 Mod 3 production was started in March 1960 by retrofitting Mark 49 Mod 1 warheads. New production of Mark 49 Mod 3 warheads began in June 1960. [6]

Mod 4, 5 and 6 warheads

For use on Jupiter, it was initially desired that the missile's reentry vehicle use ablation to cool the reentry vehicle during reentry instead of a heat sink reentry vehicle used on the Thor, Atlas and Titan. But by late 1958 it was decided that all of the missiles would be fitted with ablation reentry vehicles. This required a redesign of the Mark 49 Mod 0 warhead, the XW-49-X1. By the time the warhead entered production in April 1960, it also incorporated the firing set from the Mod 1 warhead. [10]

The Mark 49 Mod 4 only came in the Y2 yield option, [11] was 2.1 inches (53 mm) longer than the original warhead, and weighed 1,640 pounds (740 kg) and 1,732 pounds (786 kg) without and with ablative material respectively. Production was completed by October 1960. [12]

In April 1962 it was requested that a permissive device be fitted to Jupiter missiles to prevent unauthorized detonation. The modification was designed released in September 1962, producing the Mark 49 Mod 5 by converting Mod 3 warheads. The design consisted of a replacement inertial switch pack and new two-piece warhead pressure cover, and increased warhead weight by 12 pounds (5.4 kg). [13]

The final Mark 49 warhead modification was requested in December 1963. The modification consisted of converting a number of Mark 49 Y2 Mod 3 warheads by adding a self-destruct to the warheads to create the Mark 49 Mod 6. [14] These weapons were used in Program 437, an anti-satellite weapon system based on the Thor missile. [15]

Yields

The initial W49 Y1 was derived from the B28 Y1 bomb which had a yield of 1.1 megatonnes of TNT (4.6 PJ). Other sources give the yield as 1.45 megatonnes of TNT (6.1 PJ), the same as the B28 Y5 bomb. This may be the Y2 warhead yield. [1] [16]

See also

Notes

  1. 1 2 History of the Mark 49 Warhead, p. 9.
  2. ↑ History of the Mark 49 Warhead, pp. 9–10.
  3. 1 2 History of the Mark 49 Warhead, p. 10.
  4. ↑ History of the XW-35 Warhead (Report). Sandia. January 1968. p. 5. SC-M-67-669. Archived from the original on 13 May 2021. Retrieved 13 May 2021.
  5. 1 2 History of the Mark 49 Warhead, p. 13.
  6. 1 2 3 History of the Mark 49 Warhead, p. 14.
  7. ↑ Sublette, Carey (12 June 2020). "Nuclear Weapons FAQ, Section 8.0". Nuclear Weapons Archive. Retrieved 27 May 2021.
  8. ↑ "Table of Nuclides". Korea Atomic Energy Research Institute. Nuclear Data Center at KAERI. Archived from the original on 14 July 2016. Retrieved 27 May 2021.
  9. ↑ Sublette, Carey (February 2019). "2.0 Introduction to Nuclear Weapon Physics and Design". Nuclear Weapons Archive. Retrieved 13 May 2020.
  10. ↑ History of the Mark 49 Warhead, pp. 15–17.
  11. ↑ History of the Mark 49 Warhead, p. 17.
  12. ↑ History of the Mark 49 Warhead, p. 16.
  13. ↑ History of the Mark 49 Warhead, p. 18.
  14. ↑ History of the Mark 49 Warhead, p. 19.
  15. ↑ Wade, Mark (2019). "Program 437". Astronautix. Archived from the original on 12 January 2020. Retrieved 18 June 2021.
  16. ↑ Sublette, Carey (12 June 2020). "Complete List of All U.S. Nuclear Weapons". Nuclear weapon archive. Archived from the original on 27 February 2009. Retrieved 18 March 2021.

Related Research Articles

<span class="mw-page-title-main">PGM-17 Thor</span> Intermediate-range ballistic missile

The PGM-17A Thor: was the first operative ballistic missile of the United States Air Force (USAF). It was named after the Norse god of thunder. It was deployed in the United Kingdom between 1959 and September 1963 as an intermediate-range ballistic missile (IRBM) with thermonuclear warheads. Thor was 65 feet (20 m) in height and 8 feet (2.4 m) in diameter.

<span class="mw-page-title-main">B53 nuclear bomb</span> American high-yield nuclear gravity bomb

The Mk/B53 was a high-yield bunker buster thermonuclear weapon developed by the United States during the Cold War. Deployed on Strategic Air Command bombers, the B53, with a yield of 9 megatons, was the most powerful weapon in the U.S. nuclear arsenal after the last B41 nuclear bombs were retired in 1976.

<span class="mw-page-title-main">B28 nuclear bomb</span> Nuclear bomb

The B28, originally Mark 28, was a thermonuclear bomb carried by U.S. tactical fighter bombers, attack aircraft and bomber aircraft. From 1962 to 1972 under the NATO nuclear weapons sharing program, American B28s also equipped six Europe-based Canadian CF-104 squadrons known as the RCAF Nuclear Strike Force. It was also supplied for delivery by UK-based Royal Air Force Valiant and Canberra aircraft assigned to NATO under the command of SACEUR. In addition, certain U.S. Navy carrier based attack aircraft such as the A3D Skywarrior, A4D Skyhawk, and A3J Vigilante were equipped to carry the B28.

<span class="mw-page-title-main">W54</span> Nuclear warhead used by the US

The W54 was a tactical nuclear warhead developed by the United States in the late 1950s. The weapon is notable for being the smallest nuclear weapon in both weight and yield to have entered US service. It was a compact implosion device containing plutonium-239 as its fissile material, and in its various versions and mods it had a yield of 10 to 1,000 tons of TNT.

<span class="mw-page-title-main">W76</span> US thermonuclear warhead of the 1970s

The W76 is an American thermonuclear warhead, designed for use on the UGM-96 Trident I submarine-launched ballistic missiles (SLBMs) and subsequently moved to the UGM-133 Trident II as Trident I was phased out of service. The first variant, the W76 mod 0 (W76-0) was manufactured from 1978 to 1987, and was gradually replaced by the W76 mod 1 (W76-1) between 2008 and 2018, completely replacing the Mod 0 in the active stockpile. In 2018 it was announced that some Mod 1 warheads would be converted to a new low-yield W76 mod 2 (W76-2) version. The first Mod 2 warheads were deployed in late 2019.

<span class="mw-page-title-main">Medium Atomic Demolition Munition</span>

Medium Atomic Demolition Munition (MADM) was a tactical nuclear weapon developed by the United States during the Cold War. It was an atomic demolition munition (ADM), a combat engineering device for demolition of structures and for battlefield shaping. The device contained a W45 warhead with an estimated yield of 0.5 to 15 kilotonnes of TNT. Each MADM weighed 391 pounds (177 kg) in its transportation container. They were deployed between 1962 and 1986.

<span class="mw-page-title-main">W78</span> American thermonuclear warhead

The W78 is an American thermonuclear warhead with an estimated yield of 335–350 kilotonnes of TNT (1,400–1,460 TJ), deployed on the LGM-30G Minuteman III intercontinental ballistic missile (ICBM) and housed in the Mark 12A reentry vehicle. Minuteman III initially carried the older W62 warhead with a yield of 170 kilotonnes of TNT (710 TJ), but starting in December 1979 and ending in February 1982, some W62 were replaced with the W78. It is publicly estimated that 1083 warheads were manufactured.

<span class="mw-page-title-main">W50 (nuclear warhead)</span> Nuclear weapon

The W50 was an American thermonuclear warhead deployed on the MGM-31 Pershing theater ballistic missile. Initially developed for the LIM-49 Nike Zeus anti-ballistic missile, this application was cancelled before deployment. The W50 was developed by Los Alamos National Laboratory. The W50 was manufactured from 1963 through 1965, with a total of 280 being produced. They were retired from service starting in 1973 with the last units retired in 1991.

<span class="mw-page-title-main">W87</span> American thermonuclear missile warhead

The W87 is an American thermonuclear missile warhead formerly deployed on the LGM-118A Peacekeeper ("MX") ICBM. 50 MX missiles were built, each carrying up to 10 W87 warheads in multiple independently targetable reentry vehicles (MIRV), and were deployed from 1986 to 2005. Starting in 2007, 250 of the W87 warheads from retired Peacekeeper missiles were retrofitted onto much older Minuteman III missiles, with one warhead per missile.

<span class="mw-page-title-main">W47</span>

The W47 was an American thermonuclear warhead used on the Polaris A-1 sub-launched ballistic missile system. Various models were in service from 1960 through the end of 1974. The warhead was developed by the Lawrence Radiation Laboratory between 1957 and 1960.

<span class="mw-page-title-main">W62</span> American thermonuclear warhead designed in the late 1960s

The W62 was an American thermonuclear warhead designed in the 1960s and manufactured from March 1970 to June 1976. Used on some Minuteman III ICBMs, it was partially replaced by the W78 starting in December 1979, and fully replaced by W87 warheads removed from MX Peacekeeper missiles and retired in 2010.

<span class="mw-page-title-main">W56</span> American thermonuclear warhead designed in the late 1950s/early 1960s

The W56 was an American thermonuclear warhead produced starting in 1963 which saw service until 1993, on the Minuteman I and II ICBMs.

<span class="mw-page-title-main">W58</span> Nuclear weapon

The W58 was an American thermonuclear warhead used on the Polaris A-3 submarine-launched ballistic missile. Three W58 warheads were fitted as multiple warheads on each Polaris A-3 missile.

<span class="mw-page-title-main">W59</span> American thermonuclear missile warhead

The W59 was an American thermonuclear warhead used on some Minuteman I ICBM missiles from 1962 to 1969, and planned to be used on the cancelled GAM-87 Skybolt air-launched ballistic missile.

<span class="mw-page-title-main">W31</span> Nuclear warhead used by the US

The W31 was an American nuclear warhead used for two US missiles and as an atomic demolition munition.

The W30 was an American nuclear warhead used on the RIM-8 Talos surface-to-air missile and the Tactical Atomic Demolition Munition (TADM).

Kinglet was a boosted fission primary used in several American thermonuclear weapons.

<span class="mw-page-title-main">Mark 15 nuclear bomb</span> American thermonuclear bomb

The Mark 15 nuclear bomb, or Mk-15, was a 1950s American thermonuclear bomb, the first relatively lightweight thermonuclear bomb created by the United States.

The XW-35 was designed from the outset as a thermonuclear warhead for the first generation of ICBMs. Development was driven by the development of the Atlas missile, and when the accuracy of the Atlas was shown to be inferior to predictions the XW-35 design had to be altered to give a higher yield. By March 1958, the development of the XW-35-X1 was lagging. The XW-35-X1 was probably the device tested in the Koa shot of the Operation Hardtack I series. Predicted yield was 1.75 megatons; the actual yield was 1.37 megatons with the shortfall due to poor burning of the secondary. By this time the Air Force had designated the XW-49, a simple modification of the TX-28 already successfully tested during the Redwing series. By August 1958 the first dedicated missile warhead design, the W-35, had been cancelled in favor of the W-49.

References

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.