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

diesel oil Diesel fuel, also called diesel oil, heavy oil (historically) or simply diesel, 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 re ...

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

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 Janu ...

, 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 ex ...

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 or military parachutist is a soldier trained to conduct military operations by parachuting directly into an area of operations, usually as part of a large airborne forces unit. Traditionally paratroopers fight only as light infa ...

. 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 powder metallurgy, metal powder and metal oxide. When ignited by heat or chemical reaction, thermite undergoes an exothermic redox, reduction-oxidation (redox) reaction. Most varieties are not explos ...

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 A detonator is a device used to make an explosive or explosive device explode. Detonators come in a variety of types, depending on how they are initiated (chemically, mechanically, or electrically) and details of their inner working, which of ...

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 protec ...

. 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 fuse (explosives), safety fuse. They are about the same size and shape as a pencil, hence the name. They were introduced during World War ...

s or

booby-trap A booby trap is a device or setup that is intended to kill, harm or surprise a human or an animal. It is triggered by the presence or actions of the victim and sometimes has some form of bait designed to lure the victim towards it. The trap may b ...

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