Free Enterprise: Contributions of the Approach and Landing Test (ALT)Program to the Development of the Space Shuttle Orbiter

Effect of Actuator Saturation on Pilot-Induced Oscillation: A Nonlinear Bifurcation Analysis

“…We now investigate the PIO incident encountered on the Space Shuttle Enterprise, which also occurred during landing flare on the final flight (FF-5) of the approach and landing test program (ALT). The Enterprise was built for pilot training and comes without an engine and heat shield [23]. Its typical mission started on the back of a Boeing 747, where the Shuttle was released at altitude to glide back to the landing site.…”

“…Regarding the PIO, investigations by NASA concluded that a combination of rate limiting and excessive time delay led to the degraded handling quality of the Space Shuttle at landing [24]. Subsequent efforts to prevent further PIO included extensive pilot training [23] and the introduction of a new PIO-suppression filter onboard the operational Space Shuttles, which reduces the input gain at certain known problematic frequencies [25]. In this section, we examine the closed-loop frequency response of the unmodified Enterprise at landing configurationthe one in which flight FF-5 suffered the PIO.…”

Numerical and Experimental Study on Vertical Takeoff and Separation of the Compound Aircraft

“…Moreover, a classical application using vertical compound transport is that a Boeing 747 was modified as a Shuttle Carrier Aircraft (SCA) to carry Space Shuttle Enterprise to altitude for the captive and free-flight tests [10]. The primary purpose is to use the power of the SCA to provide Enterprise with the height and speed needed for testing.…”