The pioneering jet reaction (reaction control) simulation work at NACA High-Speed Flight Station, spanned the last years of the NACA organization and first NASA years (mid-to-late 1950s.) A two-phase study was begun; one was a fixed-base setup with an analog computer to solve the equations of motion and the other used a three-degree-of freedom mechanical simulator wherein the pilot experienced motions.
The analog computer simulator represented the airplane in five-degrees-of-freedom with control provided from the pilot's short control stick. The stick was unconventional for its time because it was necessary for the pilot to control about three axes through one control device. The stick pivoted fore, aft, and laterally for pitch and roll control, and lateral thumb movement provided yaw control. For most of the study, the pilot presentation consisted of an oscilloscope trace for pitch and bank angle, and a simple volt meter for angle of sideslip.
The Bell X-1B airplane offered an ideal testbed in 1957 for a trial reaction control installation. In preparation, NACA High-Speed Flight Station technicians built an iron-frame simulator, dubbed the "Iron Cross," which matched the dimensions and inertial characteristics of the X-1B, installing small reaction control thrusters on it and then mounting it on a universal joint so that a test pilot could maneuver it in pitch, roll, and yaw. The universal joint from a truck permitted motion about the three axes. High-pressure nitrogen gas was expanded selectively through the six jet nozzles to provide the reaction forces. Flight-type recorders were used to record control stick position and the various angular rates.
NACA's test pilots "flew" this mechanical ground-based simulator extensively.
