The Lewes bomb was a blast-incendiary field expedient explosive device, manufactured by mixing

diesel oil Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and t ...

and Nobel 808 plastic explosive. It was created by Lieutenant

Jock Lewes Lieutenant John Steel "Jock" Lewes (21 December 1913 – 30 December 1941) was a British Army officer prominent during the Second World War. He was the founding principal training officer of the Special Air Service.''Army News'' ustralia 11 Jan ...

, one of the original members of L Detachment SAS in 1941.

History

The SAS needed a combined incendiary and

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...

device light enough to be carried by a small group of commandos yet powerful enough to destroy and set fire to aircraft on an enemy airfield. Weighing approximately , the Lewes bomb could be carried in quantity by an individual. The only available bomb at the time was too cumbersome to be carried by a

paratrooper A paratrooper is a military parachutist—someone trained to parachute into a military operation, and usually functioning as part of an airborne force. Military parachutists (troops) and parachutes were first used on a large scale during World ...

. Lewes experimented with various types of incendiary and explosive materials, using trial and error. The final design used of

plastic explosive Plastic explosive is a soft and hand-moldable solid form of explosive material. Within the field of explosives engineering, plastic explosives are also known as putty explosives or blastics. Plastic explosives are especially suited for explos ...

, mixed with a of

thermite Thermite () is a pyrotechnic composition of metal powder and metal oxide. When ignited by heat or chemical reaction, thermite undergoes an exothermic reduction-oxidation (redox) reaction. Most varieties are not explosive, but can create brie ...

and a small amount of diesel oil and steel filings. Inside the mass was inserted a dry

guncotton Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...

booster Booster may refer to: Amusement rides * Booster (Fabbri ride), a pendulum ride * Booster (HUSS ride), an evolution of the Breakdance ride * Booster (KMG ride), a pendulum ride Arts, entertainment, and media Fictional characters * Booster, a cha ...

, plus a detonator attached to a thirty seconds

fuse Fuse or FUSE may refer to: Devices * Fuse (electrical), a device used in electrical systems to protect against excessive current ** Fuse (automotive), a class of fuses for vehicles * Fuse (hydraulic), a device used in hydraulic systems to protect ...

. Alternatively, Lewes bombs could be triggered by

pencil detonator A pencil detonator or time pencil is a time fuze designed to be connected to a detonator or short length of safety fuse. They are about the same size and shape as a pencil, hence the name. They were introduced during World War II and developed at ...

s or booby-trap firing devices such as pressure release switches. It is not clear what was used as a container for the explosive, though it was probably a small canvas bag of some sort. In use, the device was placed inside the cockpit or on the wing of an aircraft in order to ignite the aviation fuel stored within. A disadvantage of the Lewes bomb was that the detonators could be unreliable; several raids failed when their pencil-detonators were rendered unusable by heavy rain. The timing of the detonators could also be affected by the desert heat; after a raid in December 1941 one party reported the 30-minute time pencils had detonated in just 18 minutes due to the warmth of the night. In the hands of the SAS the Lewes bomb was an effective weapon against parked aircraft; following an attack in December 1941, an assessment was carried out by a group of Italian engineers on some unexploded bombs found on aircraft at their airfield. After repairing the fuses, they placed the bombs "with school-boy enthusiasm" on some old aircraft, exactly as they had been found. The result, they reported, was that "in every case the firing of the charge, besides causing considerable damage due to the explosion, set the fuel alight... causing complete destruction of the vehicle". However they also noted that the fires did not "seem to have been due to any particular qualities of the explosive, but to the accurate placing of the charges in proximity to the fuel tanks" Mortimer p43

References

Sources

* *Gavin Mortimer (2011) ''The SAS in World War II'': Osprey Publishing * World War II grenades of the United Kingdom World War II weapons of the United Kingdom Bombs Incendiary grenades Special Air Service Weapons and ammunition introduced in 1941 {{Explosive-weapon-stub