Safety and Arming Unit for the Fuze of a Projectile

A safety and arming unit with a safe separation distance device ( 14 ), which acts as a function of a free-flight incident flow and temperature, for the fuze ( 12 ) of a projectile ( 11 ), which fuze is hermetically sealed from environmental influences, has, as a measurement device for the cooling, as a function of the incident flow, of a conductor through which current passes, in the heating circuit ( 18 ) of a resistant heating element ( 16 ) which is fitted flat on the fuze casing surface ( 17 ), an electronic current measurement apparatus ( 21 ) which is connected upstream of an evaluation circuit ( 22 ), in order to ram a firing circuit. Two heating elements ( 16, 16 ''), which are fed in the same way, are preferably arranged one behind the other in the incident flow direction ( 15 ), and, additionally as an environmental temperature sensor, a comparison heating element ( 16 ') which is not influenced by the incident flow ( 15 ). This results in a reliable safe separation distance, even for slow projectiles ( 11 ), without adversely affecting their aerodynamic behaviour and independently of the environmental atmosphere.