The Opel RAK.1 (also known as the Opel RAK.3) was the world's first purpose-built rocket-powered aircraft. It was designed and built by Julius Hatry under commission from Fritz von Opel, who flew it on September 30, 1929 in front of a large crowd at Rebstock airport near Frankfurt am Main. The RAK.1 plane was part of a series of rocket-powered vehicles that were developed and demonstrated within the Opel RAK program, the world's first large-scale rocket program.