Steam cannon

The early device would consist of a large metal tube, preferably copper due to its high thermal conductivity, which would be placed in a furnace.

In theory, da Vinci believed the water would rapidly expand into vapour, blasting the projectile out of the front of the barrel.

In 1826–29, a 17.5 mm bore experimental steam cannon was developed by Colonel Karelin of the Imperial Russian Corps of Communications.

A successful World War II steam cannon was the Holman Projector, which was used to launch explosive Mills bombs into the air to create a defensive barrage against low-flying enemy aircraft.

After a successful defence of the SS Highlander in August 1940, downing two Heinkel floatplanes, there was a demand for more projectors to be fitted to small naval trawlers.

Leonardo Da Vinci 's drawing of his steam cannon. 15th century
Experimental prototype of 17.5 mm steam cannon. Russian Empire , 1826–29.
Prototype Holman Projector , an anti-aircraft grenade projector, in action in 1940