Jun 28 1977
From The Space Library
NASA announced that the second manned inert flight of the Shuttle orbiter Enterprise atop its Boeing 747 carrier, with astronauts Joe Engle and Richard Truly at the controls, was so successful that the agency had canceled a fourth test and would limit the captive flights to three. The third flight would be put off until July 28 to allow replacement of main landing-gear actuators and a leaky power unit, and installation of 100gal hydraulic reservoir tanks. The orbiter would remain mated to the 747 during the work.
The faulty auxiliary power unit had been activated on schedule about 16min into the flight; a small leak noticed before the captive-active tests had not been thought serious enough to require replacement. After the 747 had taxied to a ramp area for shutdown, the leak appeared to have increased.
The June 28 test had included tasks originally scheduled for the second and third manned tests: low- and high-speed flutter and speed-brake evaluations; a separation-maneuver test; and a fly-through of the microwave scanning-beam landing system that would guide the orbiter to earth in its first free flight. The flutter test had begun about 3min after takeoff, moving the control surfaces first of the orbiter, then of the carrier aircraft. The pilots deployed the orbiter's speed brakes to 60, 80, and 100% open positions, pausing between each setting for rudder-deflection test and flight assessment. The high-speed flutter tests at an altitude of about 20 000ft and a speed of 270 knots, followed by speed-brake tests between 20 000 and 16 000ft, were in the same sequence as the earlier tests except that the brake settings were in 10% increments.
Upon completion of these tests (34min into the flight) the carrier climbed to 20 600ft for a separation data run. "Pushover" occurred at 43min into the flight; the data run terminated with an "abort separation" order at 14 000ft. The carrier returned to 17 500ft for the automatic flythrough, followed by landing after a total flight time of 63min.
Early data from this test indicated that separation conditions would be satisfactory for free flight; that the mated configuration was flutter-free for the flight envelope; and that operating the speed brake would produce no significant buffeting. (Postflight rept, orbiter ALT #7, captiveactive flt #2, June 28/77; W Post, June 29/77, A-3; B Sun, June 29/77, 3; LA Times, June 29/77, 2; W Star, June 29/77, 2; Today, June 29/77, 10A; Av Wk, July 4/77, 18)
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