Proximity Fuze - VT and "Variable Time"

VT and "Variable Time"

The designation "VT" is often said to refer to "variable time". Fuzed munitions before this invention were set to explode at a given time after firing, and an incorrect estimation of the flight time would result in the munition exploding too soon or too late. The VT fuze could be relied upon to explode at the right time—which might vary from that estimated.

One theory is that "VT" was coined simply because Section "V" of the Bureau of Ordnance was in charge of the programme and they allocated it the code-letter "T". This would mean that the initials also standing for "variable time" was a happy coincidence that was supported as an intelligence smoke screen by the allies in World War II to hide its true mechanism.

An alternative is that it was deliberately coined from the existing "VD" (Variable Delay) terminology by one of the designers.

Developed by the US Navy, development and early production was outsourced to the Wurlitzer company, at their barrel organ factory in North Tonawanda, New York.