Laydown delivery

{{Short description|Nuclear bomb delivery mode}} [[File:Goldsboro Bomb Weapon 1 (LA-UR-20-22180).jpg|thumb|200px|Mark 39 Mod 2 thermonuclear weapon, as found by the explosive ordnance disposal team after the Goldsboro accident in 1961.]]

'''Laydown delivery''' is a mode of delivery found in some nuclear gravity bombs: the bomb's descent to the target is slowed by parachute so that it lands on the ground without detonating. The bomb then detonates by timer some time later.<ref name=b28history>{{cite report |date=August 1968 |title=History of the Mk 28 Weapon |url=https://osf.io/zyktv/ |publisher=Sandia National Laboratories |number=SC-DR-66-397 |access-date=2021-03-18 |archive-date=2021-07-07 |archive-url=https://web.archive.org/web/20210707115829/https://osf.io/zyktv/ |url-status=live |page=24|ref={{harvid|History of the Mk 28 Weapon}}}}</ref> Laydown delivery requires the weapon to be reinforced so that it can survive the force of impact.{{sfn|History of the Mk 28 Weapon|p=24-25}}

Laydown modes are used to make weapon delivery survivable by aircraft flying at low level.{{sfn|History of the Mk 28 Weapon|p=24}} Low-altitude delivery helps hide the aircraft from surface-to-air missiles.<ref name=Empire/> The ground burst detonation of a laydown delivered weapon is used to increase the effect of the weapon's blast on built-up targets such as submarine pens, or to transmit a shock wave through the ground to attack deeply-buried targets. An attack of this type produces large amounts of radioactive fallout.

==Weapons with laydown delivery options== ===United Kingdom=== The issue of aircraft survivability led to laydown being selected for the Vickers Valiant bomber of the Royal Air Force, as the design became increasingly vulnerable to Soviet weapons, especially the SA-2 missile. The low-level laydown delivery was referred to as "Equipment 2 Foxtrot" in RAF parlance; alternatives included "2 Echo" toss bombing and "2 Hotel", a particular climbing delivery method used by the Avro Vulcan.<ref name=Empire>Kristan Stoddart, [https://books.google.com/books?id=a3uKiTYlSugC&pg=PA105 "Losing an Empire and Finding a Role"], Palgrave Macmillan, 2012, pp. 104–106.</ref>

===United States=== * B28 bomb — Only in the RE (retarded external), RI (retarded internal) and FI (full-fuzing internal) versions of the weapon. The RE and RI versions of the weapon used the W28 mod 1 warhead and were an interim weapon only capable of laydown delivery at {{convert|2000|ft}} altitude, while the FI version using W28 Mod 2 and later warheads was capable of {{convert|500|ft}} delivery.{{sfn|History of the Mk 28 Weapon}} * B43 bomb — Both variants had laydown capability.<ref name="Mk43 history">{{cite report|title=HISTORY OF THE MK 43 BOMB|date=January 1968|url=https://osf.io/46sfd/files/c86mq|accessdate=5 May 2026}}</ref> * B53 bomb — Full-fuzing option (FUFO) weapon with laydown.<ref>{{cite web |url=http://nuclearweaponarchive.org/Usa/Weapons/B53.html |title=The B-53 (Mk-53) Bomb |last=Sublette |first=Carey |date=2 April 1997 |website=Nuclear Weapon Archive |publisher= |access-date=29 November 2021 |quote=}}</ref> The weapon later lost FUFO in its B53-1 upgrade in 1988, having only laydown fuzing.<ref name=Handbook>{{cite report |date=September 1990 |title=Sandia Weapon Review: Nuclear Weapon Characteristics Handbook |url=https://documents.theblackvault.com/documents/nnsa/NuclearWeaponsCharacteristicHandbook.pdf |publisher=Sandia National Labs |page=47, 64 |docket=SAND90-1238 |access-date= |quote= |ref={{harvid|Sandia Weapon Review: Nuclear Weapon Characteristics Handbook}} |archive-date=2022-01-12 |archive-url=https://web.archive.org/web/20220112004633/https://documents.theblackvault.com/documents/nnsa/NuclearWeaponsCharacteristicHandbook.pdf |url-status=live }}</ref> * B61 bomb — Full-fuzing option (FUFO) weapon with laydown. Capable of laydown delivery at {{convert|50|ft}} altitude.<ref name=b61history>{{cite report |date=August 1971 |title=History of the TX-61 Bomb |url=https://osf.io/bfjrc/ |publisher=Sandia National Laboratories |number=SC-M-71-0339 |access-date=2021-02-05 |archive-date=2021-03-30 |archive-url=https://web.archive.org/web/20210330090725/https://osf.io/bfjrc/ |url-status=live }}</ref> * B83 bomb — Full-fuzing option (FUFO) weapon with laydown.<ref>{{cite web |url=http://nuclearweaponarchive.org/Usa/Weapons/B83.html |title=The B83 (Mk-83) Bomb |last=Sublette |first=Carey |date=11 November 1997 |website=Nuclear Weapon Archive |publisher= |access-date=21 November 2021 |quote=}}</ref>

==References== {{reflist}}

Category:Nuclear weapons Category:Aerial warfare strategy Category:Aerial bombing