An underground rocket or rocket drill is a device for rapidly drilling holes through soil and rock of varying composition at rates up to 1 metre per second[1][2] by utilising supersonic jets of hot gases. It was developed by Russian engineer Mikhail Tsiferov in 1948.[3]
Proposed uses for the device included drilling shallow holes for mineral exploration, construction, underground gasification of coal, water and methane drainage.[2]
The initial design called for an autonomous device equipped with a drill head that would be rotated by expanding gases generated by a propellant burning inside a combustion chamber, in a manner similar to a Segner wheel. As the hot gases escaped the slits in the drill head at high speeds, they would break down the ground in front of the device. Experiments have shown the device could achieve drilling speed of 5 metres per minute through solid rock and up to 100 metres per minute in soil.[4] In 1970, Soviet geologist Vladimir Smirnov said, the device "may well bring about a revolution in the facilities for penetrating the interior of the earth".[5][6] While a number of experimental prototypes were made and tested, the device has not seen production.