Space Shuttle Enterprise ALT First Free Flight
The final phase of flight testing involved free-flights. These saw Enterprise mated to the SCA and carried to a launch altitude, before being released to glide to a landing on the runways at Edwards AFB. The intention of these flights was to test the flight characteristics of the orbiter itself, on a typical approach and landing profile from orbit.[5][6][7]
For the approach and landing tests, a nose strut longer that those employed in later ferry flights increased the shuttle's angle of attack relative to the 747. Prior to free flight, the 747 engines were set to full power and the paired aircraft entered a shallow dive. Increased air speed combined with the shuttle's higher angle of attack generated enough differential lift so that shuttle was effectively supporting the 747. Load cells on the three attachment points monitored the forces, informing the crew when the attachments were in sufficient tension. The mechanical connection between the two aircraft was then severed by the use of explosive bolts and the shuttle essentially dropped the 747.[8] The shuttle crew reported feeling an upward lurch on separation. The two aircraft then turned in opposite directions to maximize separation. The shuttle executed some more turns to evaluate its handling and glided to a landing.[9]
Enterprise on SCA for a ferry flight. Note lower nose position vs. approach and landing tests.
There were a total of five free-flights between August and October; the first three saw Enterprise remain fitted with its aerodynamic tail cone, intended to reduce drag when mounted on the SCA during flight. The final two had the tail cone removed, with the orbiter in its full operational configuration, with dummy main engines and OMS pods.[10] Enterprise used an air data probe mounted on its nose for these flights. These five flights were to be the only time Enterprise flew alone. Free Flight 1 was on Aug. 12, 1977 and Free Flight 4 was on Oct. 12, 1977
Read MoreFor the approach and landing tests, a nose strut longer that those employed in later ferry flights increased the shuttle's angle of attack relative to the 747. Prior to free flight, the 747 engines were set to full power and the paired aircraft entered a shallow dive. Increased air speed combined with the shuttle's higher angle of attack generated enough differential lift so that shuttle was effectively supporting the 747. Load cells on the three attachment points monitored the forces, informing the crew when the attachments were in sufficient tension. The mechanical connection between the two aircraft was then severed by the use of explosive bolts and the shuttle essentially dropped the 747.[8] The shuttle crew reported feeling an upward lurch on separation. The two aircraft then turned in opposite directions to maximize separation. The shuttle executed some more turns to evaluate its handling and glided to a landing.[9]
Enterprise on SCA for a ferry flight. Note lower nose position vs. approach and landing tests.
There were a total of five free-flights between August and October; the first three saw Enterprise remain fitted with its aerodynamic tail cone, intended to reduce drag when mounted on the SCA during flight. The final two had the tail cone removed, with the orbiter in its full operational configuration, with dummy main engines and OMS pods.[10] Enterprise used an air data probe mounted on its nose for these flights. These five flights were to be the only time Enterprise flew alone. Free Flight 1 was on Aug. 12, 1977 and Free Flight 4 was on Oct. 12, 1977
