The Photica Project:  Pronounced "Foe-Tea-Ka"

The drop shutter operation was extremely simple.  It was typically oriented on the camera so that gravity would cause a slotted slide to drop.  As the slot passed the front of the lens, the film would be exposed.  Clever designs had sensitive trigger mechanisms to reduce camera shake during exposure and one even had an interesting brake design to reduce the sudden impact when stopping.  Early lenses would exhibit element separation caused by shock over time.

These seem to be a little hard to find among camera collectors today.

     Drop Shutter Drop Shutter