Engineering topics

Wagner, Charles A.

Publications and source records attributed to Wagner, Charles A..

6 records

NASA NTRS1994

Effects of mass on aircraft sidearm controller characteristics

When designing a flight simulator, providing a set of low mass variable-characteristic pilot controls can be very difficult. Thus, a strong incentive exists to identify the highest possible mass that will not degrade the validity of a simulation. The NASA Dryden Flight Research Center has conducted a brief flight program to determine the maximum acceptable mass (system inertia) of an aircraft sidearm controller as a function of force gradient. This information is useful for control system design in aircraft as well as development of suitable flight simulator controls. A modified Learjet with a variable-characteristic sidearm controller was used to obtain data. A boundary was defined between mass considered acceptable and mass considered unacceptable to the pilot. This boundary is defined as a function of force gradient over a range of natural frequencies. This investigation is limited to a study of mass-frequency characteristics only. Results of this investigation are presented in this paper.

Wagner, Charles A.↗

NASA NTRS1991

Effects Of Frame Rates In Video Displays

Report describes experiment on subjective effects of rates at which display on cathode-ray tube in flight simulator updated and refreshed. Conducted to learn more about jumping, blurring, flickering, and multiple lines that observer perceives when line moves at high speed across screen of a calligraphic CRT.

Kellogg, Gary V.↗

NASA NTRS1991

DC isolation and protection system and circuit

A precision analog electronic circuit that is capable of sending accurate signals to an external device that has hostile electric characteristics, including the presence of very large common mode voltages. The circuit is also capable of surviving applications of normal mode overvoltages of up to 120 VAC/VDC for unlimited periods of time without damage or degradation. First, the circuit isolates the DC signal output from the computer. Means are then provided for amplifying the isolated DC signal. Further means are provided for stabilizing and protecting the isolating and amplifying means, and the isolated and amplified DC signal which is output to the external device, against overvoltages and overcurrents.

Wagner, Charles A.↗

NASA NTRS1989

Output-Isolation And Protection Circuit

Output-isolation circuit couples precise analog signals (-10 to +10 V, 0 to 20 kHz) from computer or from other electronic equipment to external electronic equipment that may be at different ground potential. Circuit functions in presence of common-mode voltages up to 2,500 Vac or 3,500 Vdc. To prevent damage from accidental connection of output leads to powerlines or other sources of high voltage, circuit includes features that protect input and output signal lines against normal-mode overvoltages up to 120 V ac or dc.

Wagner, Charles A.↗

NASA NTRS1989

Simulation at Dryden Flight Research Facility from 1957 to 1982

The Dryden Flight Research Facility has been a leader in developing simulation as an integral part of flight test research. The history of that effort is reviewed, starting in 1957 and continuing to the present time. The contributions of the major program activities conducted at Dryden during this 25-year period to the development of a simulation philosophy and capability is explained.

Smith, John P.↗

NASA NTRS1988

Effects of update and refresh rates on flight simulation visual displays

An experiment was performed to study the effects of update and refresh rates on dynamic calligraphic CRT displays, particularly those used for visual displays in flight simulators. A moving horizontal line was generated on a CRT and observed at various velocities. Observations were made with both one and two refreshes per update. The data gathered from these observations are presented on plots of refresh-update rate as a function of display velocity. The display velocity where picture degradation occurs can be found by using these plots. These velocities are related to actual simulated aircraft angular and linear velocities. Results show that a visual display updated at 30 Hz and refreshed at 60 Hz degrades at very low simulated aircraft angular and linear velocities. These velocities at which degradation occurs can be significantly increased by increasing the update rate of the visual display. Only minor improvements are possible by refreshing the display twice for each uptake. To display rapidly changing flight scenery without degradation, the display update rate must be far in excess of 60 Hz, typically several hundred Hz.

Kellogg, Gary V.↗