A rocket car is a land vehicle propelled by a rocket engine. A rocket dragster is a rocket car used for competing in drag racing, and this type holds the unofficial world record for the 1/4 mile. Fritz von Opel was instrumental in popularizing rockets as means of propulsion for vehicles. In the 1920s, he initiated together with Max Valier, co-founder of the "Verein für Raumschiffahrt", the world's first rocket program, Opel-RAK, leading to speed records for automobiles, rail vehicles and the first manned rocket-powered flight in September of 1929. Months earlier in 1928, one of his rocket-powered prototypes, the Opel RAK2, reached piloted by von Opel himself at the AVUS speedway in Berlin a record speed of 238 km/h, watched by 3000 spectators and world media, among them Fritz Lang, director of Metropolis and Woman in the Moon, world boxing champion Max Schmeling and many more sports and show business celebrities. A world record for rail vehicles was reached with RAK3 and a top speed of 256 km/h. After these successes, von Opel piloted the world's first public rocket-powered flight using Opel RAK.1, a rocket plane designed by Julius Hatry. World media reported on these efforts, including UNIVERSAL Newsreel of the US, causing as "Raketen-Rummel" or "Rocket Rumble" immense global public excitement, and in particular in Germany, where inter alia Wernher von Braun was highly influenced. The Great Depression led to an end of the Opel-RAK program, but Max Valier continued the efforts. After switching from solid-fuel to liquid-fuel rockets, he died while testing and is considered the first fatality of the dawning space age. Rocket cars are capable of very high speeds, and at one time held the land speed record (now held by a jet car). Rocket cars differ from jet-powered cars in that they carry both fuel and oxidizer on board, eliminating the need for an air inlet and compressor which add weight and increase drag.