Methods and apparatuses for electro-mechanical safety and arming of a projectile

A safety and arming apparatus for use with a projectile includes a rotor pivotable between a safe position and an armed position. A biasing element holds a mass engaged with the rotor to restrain the rotor from rotation and is deformable to allow the mass to displace and disengage from the rotor in response to a setback force on the projectile. A second biasing element includes a displaceable end for engaging with the rotor to restrain the rotor from rotation and is deformable to disengage the displaceable end from the rotor in response to projectile spin. A piston actuator can rotate the rotor to the armed position if the mass is disengaged and the displaceable end is disengaged. A detonator on the rotor can be aligned with a detonation cord when the rotor is in the armed position and unaligned when the rotor is in the safe position.