Based on the guidelines laid down by the German "Reichverkehrsministerium" (Reich Ministry of Transport), MTU-Museum Triebwerksgeschichte – gestern, heute und morgen, on www.mtu.de (German, PDF, 4,4 MB) in 1930 Daimler-Benz began development of a new aero engine of the 30 litres displacement class: a liquid-cooled inverted-vee 12-cylinder piston engine.