English: Jerrie Cobb, a well known female pilot in the 1950s, testing Gimbal Rig in the Altitude Wind Tunnel, AWT in April 1960. The Gimbal Rig, formally called MASTIF or Multiple Axis Space Test Inertia Facility, was used to train astronauts to control the spin of a tumbling spacecraft. Jerrie Cobb was the first female to pass all three phases of the Mercury Astronaut Program but NASA rules stipulated that only military test pilots could become astronauts and there were no female military test pilots. Jerrie completed this astounding feat in 1961. The MASTIF was installed at the Altitude Wind Tunnel at the Lewis Research Center, now John H. Glenn Research Center.