The fastest propeller-driven plane ever made is the Hughes H-4 Hercules, also known as the "Spruce Goose." Designed and built by Howard Hughes in the 1940s, it holds the record for the largest wingspan of any aircraft ever flown. However, it's important to note that the Hughes H-4 Hercules made only one flight and was not put into regular production or service.
During its first and only flight on November 2, 1947, the Spruce Goose reached a top speed of around 135 miles per hour (217 kilometers per hour) and flew for approximately one mile (1.6 kilometers). While it was a remarkable engineering feat due to its immense size, the Spruce Goose was not designed for speed and was primarily intended for use as a heavy transport aircraft during World War II.
In terms of speed comparison to modern jets, the performance of the Spruce Goose falls far short. Modern jet aircraft, such as commercial airliners or military fighter jets, are significantly faster. Commercial airliners like the Boeing 747 or the Airbus A380 can fly at speeds of approximately 560-590 miles per hour (900-950 kilometers per hour). Military jets can go even faster, with some fighter jets reaching speeds of Mach 2 or more, which is twice the speed of sound (around 1,500-1,600 miles per hour or 2,414-2,575 kilometers per hour).
Therefore, while the Hughes H-4 Hercules was an impressive achievement for its time, it cannot match the speed capabilities of modern jet-powered aircraft.