English: The Space Shuttle prototype Enterprise flies free after being released from NASA's 747 Shuttle Carrier Aircraft (SCA) during one of five free flights carried out at the Dryden Flight Research Center, Edwards, California in 1977, as part of the Shuttle program's Approach and Landing Tests (ALT). The tests were conducted to verify orbiter aerodynamics and handling characteristics in preparation for orbital flights with the Space Shuttle Columbia. A tail cone over the main engine area of Enterprise smoothed out turbulent airflow during flight. It was removed on the two last free flights to accurately check approach and landing characteristics.