The Dornier Do 335 Pfeil ("Arrow") is a heavy fighter built by Dornier for Germany during World War II. The Pfeil's performance was predicted to be better than other twin-engine designs due to its unique push-pull configuration and the lower aerodynamic drag of the in-line alignment of the two engines. It was Germany's fastest piston-engined aircraft of World War II. The Luftwaffe was desperate to get the design into operational use, but delays in engine deliveries made it impossible.