Scary- real-life Vought SLAM (aka Project Pluto, aka Flying Crowbar) was the only confirmed doomsday machine ever attempted but cancelled out of fear. The nuclear ramjet engine was developed along with a scale model. The autonomous unmanned missile/bomber would carry between 12-24 nukes and travel at Mach 3 sustained over entire areas of the WP and USSR lobbing nukes at targets and outrunning the blast while at the same time flying so low as to create a destructive wake that would destroy anything in its path. Finally, after all 12 nukes were used up, the machine would continue to burn out the dirty nuclear ramjet and contaminate everywhere it flew... and when the engine started to fail the machine would select one last target and ram into it at Mach 3!!!