X-15 Historical Footage!!! The X-15 is a famous and significant part of aviation history. Its purpose was to fly high and fast, testing the machine and subjecting pilots to conditions that future astronauts would face. It made the first manned flights to the edges of space and was the world’s first piloted aircraft to reach hypersonic speeds, or more than five times the speed of sound. The X-15 was an important tool for developing spaceflight in the 1960s, and pilots flying above 50 miles altitu