World War II saw a great increase in the pace of development and production, not only of aircraft but also the associated flight-based weapon delivery systems.
Not only airplanes, but also helicopters saw rapid development in the Second World War, with the introduction of the Focke Achgelis Fa 223, the Flettner Fl 282 synchropter in 1941 in Germany and the Sikorsky R-4 in 1942 in the USA.