Bimal L. Aponso

Simulation investigation of the effects of helicopter hovering dynamics on pilot performance

A fixed base simulation has been performed to investigate the handling qualities requirements for the mid-term pitch response of a helicopter at hover and in low-speed flight. Pilot rating results from this simulation were compared with those from previous experiments to develop handling qualities limits on the frequency and damping of the oscillatory mode in the hovering cubic. Pilot performance data obtained during the experiment were used to confirm the pilot rating results. These data show the pilot performance to closely match that predicted by the theory of piloted control. A means of predicting pilot ratings from the open-loop aircraft dynamics is presented.

TACTICAL INSERTION MISSION PLANNING AND REHEARSAL USING VIRTUAL REALITY SIMULATION

Systems Technology, Inc. (STI) has developed a versatile new system for parachute mission planning and rehearsal, combining the validated technology of STIs PC-based PARASIM parachute simulation system with real-time interactive networking, powerful scene generation graphics tools, and terrain-correlated wind fields. This Tactical Insertion Mission Planning and Rehearsal Simulator (TIMPARS) was developed under the SBIR program, funded by the US Special Operations Command (SOCOM). The TIMPARS system rests on four cornerstones: the PARASIM  simulation software, the real-time interactive network, the scene generation toolkit, and the terrain-correlated wind generation module. These elements combine to produce a system with which users can utilize geospecific terrain data and imagery to recreate a real-world site as a simulation scene, input actual or forecasted wind speeds and directions at altitude above the chosen location to generate a terrain-correlated wind field specific to the simulation scene, and then plan and rehearse a mission in a real-time simulation environment with multiple live participants interacting in the same virtual space. BACKGROUND STIs original parachute simulator was developed for use by smokejumpers, US Forestry Service airborne firefighters. Designed to teach round and ramair canopy control, this early version employed rudimentary graphics with a fixed monitor; users stood before the display monitor and pulled simple toggle lines to maneuver in the simulation. Despite the austere configuration, this version provided the minimum cues required to teach parachute flight safely at low cost. In 1996, STI launched a major development effort to incorporate new photo- realistic graphics and head-mounted display/virtual reality technology into the simulator. Subsequent development efforts produced malfunctions procedures software, riser controls, harness switches, and additional simulator improvements. The implementation of these enhanced simulators by the US Marine Corps (USMC) and the Military Freefall School in Yuma, AZ, resulted in a drastic drop in the rate of training injuries. In particular, the USMC First Force Reconnaissance Company experienced a 75% reduction in main canopy cutaways after implementing the enhanced simulator in the MC-5 static line deployed ram-air parachute system (SLDRAPS) transition course at Camp Pendleton, CA. TIMPARS PROJECT

Feel Systems and Flying Qualities

There is a continuing controversy over the importance of the cockpit control feel system on the pilots assessment of airplane flying qualities. This paper reviews the issues involved in this comoversy, including the results of recell! flight research experimenls that have investigated fee l systems. II is concluded that the feel system is 001 transparent to the pi10l and therefore must be accourued for in flying-qualities eva1uatioDS. The lack of consisteD! data, however, makes it difficu]t to define criteria explicitly tailored for the feel system, so recommended requiremeoo: am methods for dealing with feel systems in the current military specifications are provided.

Development of roll attitude quickness criteria for fighter aircraft

A recent effort undertaken for the Air Force Flight Dynamics Directorate provided proposed revisions to the flying qualities military standard. The intent of these revisions was to create the structure necessary for a mission-oriented specification. A significant portion of this effort focused on the development of roll and pitch attitude quickness criteria for moderate-amplitude maneuvering. This paper describes the piloted simulation experiment that was conducted to meet this end. The primary emphasis of the expcrimcnt was on aggressive maneuvering in roll. Handling qualities ratings from the lateral axis evaluations were used to develop flying qualities boundaries. The results suggest that roll damping highc than that currently specified is required for Level 1 flying qualities. Flying qualities requirements on roll attitude quickness are proposed. These requirements allow for a reduction in effective roll damping as maneuver amplitude increases.