Simulated Flight Tests of a Digitally Autopiloted Stol-Craft on a Curved Approach With Scanning Microwave Guidance

A work is described which studied the capabilities of a STOL aircraft equipped with digital minicomputer serving as an autopilot making a curved approach to a runway along a path prescribed by the Air Traffic Control system using radio-navigation data supplied by the developing Scanning Fan Beam Microwave Landing Guidance System. The work involved the development of an ATC scheme for effectively generating a flyable curved approach path and specifying such a path to the aircraft being served. The paths produced are made up of alternating straight and circular segments along which the plane is to maintain prescribed constant airspeeds. The digital autopilot functions include Navigation, Control Trimming, Anticipatory calculations, Generation of Control Commands based on utilization of linear optimal state-feedback control theory, Filtering (including Kalman techniques) of state measurements, and Estimation of prevailing winds. A complete simulation of such a system aboard a McDonnell-Douglas 188/Breguet 941 STOL transport, with realistic winds, turbulence, and measurement noise, was created and exercised on the Purdue University CDC 6500 computer system, and showed the capability of excellent adhesion of the airplane to the commanded flight path.