Under the pressures of war, many proven aircraft designs underwent a continual process of variation. At a somewhat frantic pace, significant resources were thrown at attempts to out-class enemy aircraft with all sorts of novel design concepts for better speed, maneuverability and weapon systems. In this race the Messerschmitt Me 262 was a proven airframe that lent itself to many variations – some remained on the drawing board while others pushed the limits of aircraft design to the limits of the day.