Gordon H. Hardy

Flight evaluation of pursuit displays for precision approach of powered-lift aircraft

Flight experiments with NASA Ames Research Centers quiet short-haul research aircraft evaluated the influence of pursuit displays on the ability of pilots to execute precision-instrument flight operations in the terminal area, particularly approaches to and landings on a short runway. The aircraft is a powered-lift, short-takeoff and landing configuration equipped with a modern digital fly-by-wire flight control system, a head-up display, and a color head-down display that make it possible to investigate control and display concepts for full-envelope, powered-lift operations. Flight-path-oriented displays that provide status and command information in a format with minimal clutter were investigated. The pilots could fly the aircraft with the precision associated with flight-director guidance and with a high degree of situation awareness. The primary benefits of this display concept were realized when the pilot was required to execute a complex transition and approach under instrument conditions and in the presence of a wide range of wind and turbulence conditions.

Flight Evaluation of Augmented Controls for Approach and Landing of Powered-Lift Aircraft

Flight experiments were conducted with Ames Research Centers Quiet Short-Haul Research Aircraft to evaluate the influence of highly augmented control modes on the ability of pilots to execute precision instrument flight operations in the terminal area, particularly approaches to and landings on a short runway. The aircraft is a powered-lift, short-takeoff and landing configuration that is equipped with a modern digital fly-by-wire flight control system, a head-up display, and a color head-down display that make it possible to investigate control concepts and display format and content for full envelope, powered-lift operations. Considerable attention has been devoted in this flight program to assessing flightpath and airspeed command and stabilization modes developed using nonlinear, inverse model-following methods. The primary benefit of this control concept was realized when the pilot was required to execute a complex transition and approach under instrument conditions and in the presence of a wide range of wind and turbulence conditions. The concept and its design criteria have been defined to the point that is ready for consideration for aircraft design when warranted by mission requirements or complex control configurations.

Pursuit Display Review and Extension to a Civil Tilt Rotor Flight Director

This paper reviews almost thirty years of developing pursuit displays at the NASA Ames Research Center and shows how this work was applied to a Civil Tiltrotor. It then uses this previous work to develop an “Inverse” flight director to reduce pilot workload during the transition from the frontside to backside configuration while still preserving the advantages of the basic pursuit displays. The results from the Vertical Motion Simulator at NASA Ames showed that satisfactory performance and handling qualities were obtained for the transition from the cruise frontside to the final approach and landing backside configuration for a precision descending, decelerating, and turning approach under instrument conditions with normally expected crosswinds and turbulence.

Simulation evaluation of a low-altitude helicopter flight guidance system adapted for a helmet-mounted display

A computer aiding concept for low-altitude helicopter flight has been developed and evaluated in a real-time piloted simulation. The concept included an optimal control trajectory-generation algorithm based upon dynamic programming, and a helmet-mounted display (HMD) presentation of a pathway-in-the-sky, a phantom aircraft, and flight-path vector/predictor guidance symbology. The pilot evaluation was conducted at the NASA-Ames Research Center moving base vertical motion simulator by pilots representing NASA, the US Army, Air Force, and helicopter industry. The pilot manually tracked the trajectory generated by the algorithm utilizing the HMD symbology. The pilots were able to perform the tracking tasks satisfactorily while maintaining a high degree of awareness of the outside world.<<ETX>>

Simulation evaluation of transition and hover flying qualities of the E-7A STOVL aircraft

The generalized simulation model developed for the E-7A STOVL fighter-type aircraft configuration has attempted to define the limits of acceptibility for a vertical-to-horizontal-to-vertical flight transition envelope. An effort was also made to determine the control power required during hover and transition, and to evaluate whether the integration of flight and propulsion controls thus far effected achieves good flying qualities throughout the low-speed flight envelope. The results thus obtained furnish a general view of the acceptable transition corridor, expressed in terms of the minimum-climb capability.

Comparison of manual and autopilot breakout maneuvers with three closely spaced parallel runway approaches

This study used a high-fidelity flight simulator to explore approach operations for three closely-spaced parallel runways using autopilot and manually flown breakout procedures. An initial study investigated the concept under manual control mode only. The concept aimed to achieve visual meteorological conditions capacities under instrument meteorological conditions when landing aircraft on runways as close as 750 ft apart. This investigation studied procedures related to autopilot breakout maneuvers for triple parallel aircraft flying in an echelon formation and compared them to the manual procedures investigated earlier. All of the data collection runs had an off-nominal situation, which was either caused by the wake of the lead aircraft drifting too close to the center and trailing aircraft, or the lead aircraft deviating from its course and blundering towards the center and trailing aircraft. The location of the off-nominal situation (high/low altitude) and the position of the ownship (center or right runway) were also manipulated. Statistically significant results showed that autopilot breakout maneuvers were flown more accurately than manual breakout maneuvers. Some improved lateral separation was also observed between the paired aircraft while the autopilot was used, which could be attributed to the improved accuracies with which the breakout maneuver was flown using autopilot. On the subjective ratings, pilots experienced reduced workload, a similar level of situation awareness, and a reduced level of situational demands under the autopilot condition. Objective and subjective data from the current study extends the results from the previous research [1], with some evidence to suggest further improvement in these factors when autopilot breakout procedures are used.

Tactical Flight Management Concept for Trajectory Based Operations

This paper introduces the concept of tactical flight management and outlines methods for implementation. In this context, the distinction between strategic and tactical is unrelated to the construction of a flight plan that is composed of a sequence of waypoints. Rather it distinguishes between approaches for generating and guiding aircraft along trajectories that connect these waypoints. This paper focuses on the descent phase of flight where the goal is to fly an idle thrust descent from cruise down to the runway. The conventional approach is to generate a strategic trajectory that optimizes performance while complying with constraints. Guidance is then provided to fly the aircraft along this static trajectory, deviating when necessary by transitioning between guidance modes. The proposed approach is to generate a guidance trajectory that is continually updated to achieve tactical objectives. This motion-based trajectory will represent an extension of the aircraft’s current state, and incorporate control laws and mode transition logic as part of the trajectory. This paradigm shift can provide a number of advantages when operating in the highly constrained and dynamic environment of the next generation air transportation system. These advantages include improved constraint compliance, reduced occurrences of mode confusion, and increased situational awareness of what the automation is doing now and what it is going to do in the future.

EVALUATION OF FLYING QUALITIES AND GUIDANCE DISPLAYS FOR AN ADVANCED TILT-WING STOL TRANSPORT AIRCRAFT IN FINAL APPROACH AND LANDING

A piloted simulation was performed on the Vertical Motion Simulator at NASA Ames Research Center to evaluate flying qualities of a tilt-wing Short Take-Off and Landing (STOL) transport aircraft during final approach and landing. The experiment was conducted to assess the design’s handling qualities, and to evaluate the use of flightpath-centered guidance for the precision approach and landing tasks required to perform STOL operations in instrument meteorological conditions, turbulence, and wind. Pilots rated the handling qualities to be satisfactory for all operations evaluated except those encountering extreme crosswinds and severe windshear; even in these difficult meteorological conditions, adequate handling qualities were maintained. The advanced flight control laws and guidance displays provided consistent performance and precision landings.

Loss-of-Control Mitigation via Predictive Cuing

Flying near the edge of the safe operating envelope is an inherently unsafe proposition. The edge of the envelope here implies that small changes or disturbances in the system state or system dynamics can take the system out of the safe envelope in a short time and could result in loss-of-control events. This study evaluates approaches to pilot cueing based on predicting loss-of-control safety margins as the aircraft gets closer to the edge of the safe operating envelope. The goal is to provide the pilot aural, visual, and tactile cues focused on maintaining the pilot’s control action within predicted loss-of-control boundaries. The predictive architecture presented in this paper combines quantitative loss-of-control boundaries, an adaptive prediction, and data-based predictive control algorithms. The combined architecture is applied to a nonlinear transport-class aircraft. Evaluations of various loss-of-control cues using both test and commercial pilots in the NASA Ames Research Center’s vertical motion-...

Simulation development of a forward sensor-enhanced low-altitude guidance system

The requirement to operate aircraft at low-altitude near the terrain is common in the military community and essential for helicopters. The risk and crew workload in this flight regime is severe, with navigation, guidance, and obstacle avoidance demanding high attention, A guidance system relying on digitized terrain elevation maps has been developed that employs airborne navigation, mission requirements, aircraft performance limits, and radar altimeter returns to generate a valley-seeking, low-altitude trajectory between waypoints for display to the pilot. This system has been flight demonstrated to 150 ft above ground level attitude, and is primarily limited by the ability of the pilot to perform obstacle detection and avoidance. In this study, a wide field of view forward sensor has been modeled and incorporated in the guidance system for the purpose of relieving the pilot of the obstacle avoidance duty. The results of a piloted, motion-based simulation of this enhanced low-altitude guidance system is presented. Simulated flights to 50 ft altitude in the presence of obstacles were demonstrated while maintaining situational awareness and close tracking of the guidance trajectory.<<ETX>>