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NASA and the U.S. Army have designed, developed, and tested a Computer Aiding for Low-Altitude Helicopter Flight guidance system. This system provides guidance to the pilot for near-terrain covert helicopter operations. The guidance is presented to the pilot through symbology on a helmet mounted display. This system has demonstrated the feasibility of a pilot-centered concept of terrain flight guidance that preserves pilot flexibility and authority. The system was developed using extensive piloted simulation and then implemented in a UH-60 Blackhawk helicopter for flight development and evaluation. A close correlation between simulation and actual flight was found; however, in flight overall pilot workload increased and performance decreased. This paper presents a description of the basic system design, simulation, and flight evaluations.

The paper describes a high performance Head-Up Display (HUD) guidance system installed on the experimental powered-lift STOL aircraft “Aska”. Since the maiden flight in October, 1985, the HUD system has been used in all the flight tests. The HUD has an accurate flight path symbol generated by inertial velocity from the IRS which is updated by up-linked precision radar position data. The flight path symbol is very useful for precise approach and flare control for Aska which has large ground effects. A synthetic runway is also presented, which is conformal with the real runway, using the position data from the ground tracking radar system. Under Instrument Meteorological conditions (IMC), the pilot can approach and land using the HUD synthetic runway as well as in Visual Meteorological Conditions (VMC). The HUD system proved to be a valuable aid to the pilot for all the Aska flight tests.

Using a generalized simulation model developed for piloted evaluations of short take-off/vertical landing aircraft, an initial fixed-base simulation of a mixed-flow, remote-lift configuration has been completed. Objectives of the simulation were to evaluate the integration of the aircraft's flight and propulsion controls to achieve good flying qualities throughout the low-speed flight envelope; to determine control power used during transition, hover, and vertical landing; and to evaluate the transition flight envelope considering the influence of thrust deflection of the remote-lift component. Pilots’ evaluations indicated that Level 1 flying qualities could be achieved for deceleration to hover in instrument conditions, for airfield landings, and for recovery to a small ship when attitude and velocity stabilization and command augmentation control modes were provided.

A generalized simulation model has been prepared for use in conducting piloted evaluations of short takeoff/vertical landing aircraft, and an initial fixed-base simulation of the General Dynamics E-7A configuration has been completed. Objectives of the simulation were to define the acceptable transition flight envelope, determine control power used during transition and hover, and evaluate the integration of the aircraft's flight and propulsion controls to achieve good flying qualities throughout die low-speed flight envelope. Results provide a general view of the acceptable transition corridor, expressed in terms of minimum climb capability. Pilots' evaluations indicated that Level 1 flying qualities could be achieved for deceleration to hover in instrument conditions, for airfield landings, and for recovery to a small ship when attitude and velocity stabilization and command augmentation control modes were provided.

This paper describes a combined display and control system to provide high-precision manual landing flare and touchdown, and presents the results of a preliminary flight evaluation using the NASA Quiet Short-Haul Research Aircraft (QSRA). A head-up display presents flare commands to the pilot, who executes a simple, repeatable nominal flare maneuver. Height and height rate errors relative to the desired trajectory are fed back to a low-authority (±0.05g) direct-lift-control system that drives spoilers and throttles so as to null the errors resulting from gusts and pilot deviations. This integrated cockpit display and closed-loop control constitutes a trajectory augmentation system that extends the QSRA flight control from augmentation of attitude, flightpath angle, and airspeed (previously reported) to augmentation of the trajectory itself. The pilot can easily over-ride the low-authority closed-loop control, and a monitored simplex system is adequate for safely.