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 by utilising supersonic jets of hot gases. It was developed by Russian engineer Mikhail Tsiferov in 1948. Proposed uses for the device included drilling shallow. .
Further development led to the first prototype, built in 1968. The device consisted of a cylindrical shell filled with solid propellant, with. .
• Жолондковский, О. (1966). [Underground voyage of fiery endmill]. (in Russian) (12).• .
SolidThe solid fuel version of the device was limited by the volume of propellant it could carry, which was sufficient for 5 to 20 seconds of operation, enough to create a well up to 20 metres deep. The inventor saw further.
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