Butterfly Bomb

A Butterfly Bomb, or (Sprengbombe Dickwandig 2 kg or SD2) was a German 2 kilogram anti-personnel submunition used by the Luftwaffe during the Second World War. It was so named because the thin cylindrical metal outer shell which hinged open when the bomblet deployed gave it the superficial appearance of a large butterfly. The design was very distinctive and easy to recognise. SD2 bomblets were not dropped individually, but were packed into containers containing between 6 and 108 submunitions e.g. the AB 23 SD-2 and AB 250-3 submunitions dispensers. The SD2 submunitions were released after the container was released from the aircraft and had burst open. This bomb type was one of the first cluster bombs ever used in combat and it proved to be a highly effective weapon.

Description

The SD2 submunition was an 8 cm long cylinder of cast iron, which was slightly smaller in diameter before its vanes deployed. A steel cable 15 cm long was attached via a spindle to the fuze screwed into the fuze pocket in the side of the bomblet. The outer shell would hinge open as two half-cylinders when it was dropped and spring-loaded vanes at the ends would flip out. These rotated the spindle as the bomblet fell, arming the fuze. Butterfly bombs contained 225 grams of TNT. They were generally lethal to anyone within a radius of 25 metres and could inflict serious shrapnel injuries (e.g. penetrating eye wounds) as far away as 100 metres. Butterfly bombs were usually painted dark green. However, sometimes a dull yellow colour scheme was used, either for use in the middle east, or when dropped on grain crops at harvest time to kill farm-workers.

Butterfly bombs could be fitted with any one of three fuzes:

* 41 fuze - triggered detonation immediately on impact with the ground
* 67 fuze - clockwork time delay adjustable between 5 and 30 minutes after impact
* 70 fuze - anti-handling device (i.e. boobytrap), triggering detonation if the bomb was moved in any way after the initial impact with the ground

Note: butterfly bombs in a submunitions container could have the full range of fuzes fitted, to increase disruption to the target. Additionally, fuze variants such as the 41A, 41B, 70B1, 70B2 etc existed. These variants were inserted into the fuze pocket via a bayonet fitting, but were otherwise identical.

On October 28, 1940, some butterfly bombs that had incompletely armed themselves were discovered in Ipswich by British ordnance technicians Sergeant Cann and 2nd Lieutenant Taylor. By screwing the arming rods back into the fuzes (i.e. the unarmed position), the two men were able to recover safe examples for scientific examination, in order to discover how the bombs functioned.

As with more modern cluster bombs, it was not considered practical to defuze butterfly bombs which had fully armed themselves but failed to detonate (particularly those fitted with the type 70 fuze), due to the extreme risks involved. The standard render safe procedure for any unexploded butterfly bomb was to evacuate the area for at least 30 minutes (in case the bomblet was fitted with a type 67 time delay fuze), then destroy it in situ by detonating a small explosive charge next to it. Other solutions were to attach a long string to the bomb and tug on it after taking cover, or for bombs in open countryside, shooting at them with a rifle from a safe distance.

Use

Butterfly bombs were first used against Ipswich in 1940, but were also dropped on Grimsby and Cleethorpes in June 1943, amongst various other targets in the UK. They were subsequently used against Allied forces in the Middle East. The British Government deliberately suppressed news of the damage and disruption caused by butterfly bombs in order not to encourage the Germans to keep using them.

The SD2 saw use in the opening stages of Operation Barbarossa, the German invasion of the Soviet Union, which began on 22 June 1941. Twenty to thirty aircrews had been picked to drop SD2s and SD10s (10 kg submunitions) on key Soviet airfields, a flight of three aircraft being assigned to each field. The purpose of these early attacks was to cause disruption and confusion as well as to preclude dispersion of Soviet planes until the main attack was launched. [Citation | last = Ratley III | first = Major Lonnie O. | author-link = | last2 = | first2 = | author2-link = | title = A Lesson of History: The Luftwaffe and Barbarossa | journal = Air University Review | volume = | issue = | pages = | date = March-April 1983 | year = | url = http://www.airpower.maxwell.af.mil/airchronicles/aureview/1983/mar-apr/ratley.htm | doi = | id = ] It was reported that Kampfgeschwader 51 had lost 15 aircraft due to accidents with the SD2s, nearly half of the total Luftwaffe losses that day. [Citation | last = Price | first = Dr Alfred | author-link = | last2 = | first2 = | author2-link = | title = Pre-Emptive Strike | journal = Air Power Review | volume = 6 | issue = 3 | pages = | date = Autumn 2003 | year = | url = | doi = | id = ]

The last recorded death from a German butterfly bomb in England took place on November 27, 1956, over 11 years after the Second World War ended: Flight Lieutenant Herbert Denning of the RAF was examining an SD2 at the Upminster bomb cemetery, East of RAF Hornchurch, when it detonated. He died of shrapnel and blast injuries at Oldchurch Hospital the same day.

US copy

The United States manufactured a copy of the SD2 for use during the Korean War and Vietnam War, designating it the M83 Butterfly Bomb.

Notes

External links

* [http://www.youtube.com/watch?v=CWsnfK-MeCE British Govt Information Film from WW2, warning of the SD2 threat]
* [http://www.inert-ord.net/usa03a/usa6/bfly/index.html Description of the M83, a US copy of this design]
* [http://www.millsgrenades.co.uk/images/german%20bombs/sd2a.jpgAdditional photo of butterfly bomb]

ee also

Thermos Bomb