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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

A method for determining transport delays in the flight simulation environment

This paper will describe the process of transport delay measurement along several points in the signal path for a piloted flight simulation. Several transport delay measurement techniques were compared to determine the accuracy and ease of use of each method. Measurements were made in both the frequency and time domain. The transport delays for individual pieces of equipment as well as the math model of the simulated vehicle are measured and broken out from the system's total transport delay.

Smith, R. M.↗
NASA NTRS1999

Development of a Free-Flight Simulation Infrastructure

In anticipation of a projected rise in demand for air transportation, NASA and the FAA are researching new air-traffic-management (ATM) concepts that fall under the paradigm known broadly as ":free flight". This paper documents the software development and engineering efforts in progress by Seagull Technology, to develop a free-flight simulation (FFSIM) that is intended to help NASA researchers test mature-state concepts for free flight, otherwise referred to in this paper as distributed air / ground traffic management (DAG TM). Under development is a distributed, human-in-the-loop simulation tool that is comprehensive in its consideration of current and envisioned communication, navigation and surveillance (CNS) components, and will allow evaluation of critical air and ground traffic management technologies from an overall systems perspective. The FFSIM infrastructure is designed to incorporate all three major components of the ATM triad: aircraft flight decks, air traffic control (ATC), and (eventually) airline operational control (AOC) centers.

Miles, Eric S.↗
NASA NTRS1995

A study of workstation computational performance for real-time flight simulation

With recent advances in microprocessor technology, some have suggested that modern workstations provide enough computational power to properly operate a real-time simulation. This paper presents the results of a computational benchmark, based on actual real-time flight simulation code used at Langley Research Center, which was executed on various workstation-class machines. The benchmark was executed on different machines from several companies including: CONVEX Computer Corporation, Cray Research, Digital Equipment Corporation, Hewlett-Packard, Intel, International Business Machines, Silicon Graphics, and Sun Microsystems. The machines are compared by their execution speed, computational accuracy, and porting effort. The results of this study show that the raw computational power needed for real-time simulation is now offered by workstations.

Maddalon, Jeffrey M.↗
NASA NTRS1975

A study for active control research and validation using the Total In-Flight Simulator (TIFS) aircraft

The results of a feasibility study and preliminary design for active control research and validation using the Total In-Flight Simulator (TIFS) aircraft are documented. Active control functions which can be demonstrated on the TIFS aircraft and the cost of preparing, equipping, and operating the TIFS aircraft for active control technology development are determined. It is shown that the TIFS aircraft is as a suitable test bed for inflight research and validation of many ACT concepts.

Chen, R. T. N.↗
NASA NTRS1978

Simulated flight effects on noise characteristics of a fan inlet with high throat Mach number

An anechoic wind tunnel experiment was conducted to determine the effects of simulated flight on the noise characteristics of a high throat Mach number fan inlet. Comparisons were made with the performance of a conventional low throat Mach number inlet with the same 50.8 cm fan noise source. Simulated forward velocity of 41 m/sec reduced perceived noise levels for both inlets, the largest effect being more than 3 db for the high throat Mach number inlet. The high throat Mach number inlet was as much as 7.5 db quieter than the low throat Mach number inlet with tunnel airflow and about 6 db quieter without tunnel airflow. Effects of inlet flow angles up to 30 deg were seemingly irregular and difficult to characterize because of the complex flow fields and generally small noise variations. Some modifications of tones and directivity at blade passage harmonics resulting from inlet flow angle variation were noted.

Wesoky, H. L.↗
NASA NTRS1973

A flight simulator for advanced aircraft - Servo design to realization.

Discussion of computer-aided design results obtained for a moving-base, three-man flight simulator. From a control viewpoint, the structure is discussed in terms of disturbance torques, damping ratios, natural frequencies, load acceleration, and smoothness. The use of inertia to achieve well-behaved structural transfer functions and smooth or high fidelity load accelerations is demonstrated. Transfer functions in the complex frequency domain, as well as time-dependent solutions to the system, are derived. The relative merits of using position and/or velocity as primary feedback, for a limited travel acceleration device, are discussed. Root locus plots, which were utilized in the control-system design, Bode plots, and time-dependent plots are drawn. In addition, the theoretical ratio of velocity to commanded input Bode plot is compared to the experimental results, and the dramatic effect on the load smoothness plot caused by selecting velocity over position as primary feedback is shown.

King, R. F.↗
NASA NTRS2000

Rapidly Re-Configurable Flight Simulator Tools for Crew Vehicle Integration Research and Design

While simulation is a valuable research and design tool, the time and difficulty required to create new simulations (or re-use existing simulations) often limits their application. This report describes the design of the software architecture for the Reconfigurable Flight Simulator (RFS), which provides a robust simulation framework that allows the simulator to fulfill multiple research and development goals. The core of the architecture provides the interface standards for simulation components, registers and initializes components, and handles the communication between simulation components. The simulation components are each a pre-compiled library 'plug-in' module. This modularity allows independent development and sharing of individual simulation components. Additional interfaces can be provided through the use of Object Data/Method Extensions (OD/ME). RFS provides a programmable run-time environment for real-time access and manipulation, and has networking capabilities using the High Level Architecture (HLA).

Schutte, Paul C.↗
NASA NTRS2002

Rapidly Re-Configurable Flight Simulator Tools for Crew Vehicle Integration Research and Design

While simulation is a valuable research and design tool, the time and difficulty required to create new simulations (or re-use existing simulations) often limits their application. This report describes the design of the software architecture for the Reconfigurable Flight Simulator (RFS), which provides a robust simulation framework that allows the simulator to fulfill multiple research and development goals. The core of the architecture provides the interface standards for simulation components, registers and initializes components, and handles the communication between simulation components. The simulation components are each a pre-compiled library 'plugin' module. This modularity allows independent development and sharing of individual simulation components. Additional interfaces can be provided through the use of Object Data/Method Extensions (OD/ME). RFS provides a programmable run-time environment for real-time access and manipulation, and has networking capabilities using the High Level Architecture (HLA).

Pritchett, Amy R.↗
NASA NTRS1979

In-flight simulation with pilot-center of gravity offset and velocity mismatch

Similarity transformations which preserve modal characteristics and pilot's acceleration cues in in-flight simulation are presented. The model transformation for lateral acceleration matching is developed. A velocity-mismatch example, based on a VRA simulation of the Space Shuttle, illustrates that acceleration matching is achieved at the expense of mismatching in cues which are secondary to the simulated piloting task, while primarily cues are preserved. The approach is applicable for both implicit and explicit model-following, and it can easily be extended to the longitudinal case.

Stengel, R. F.↗
NASA NTRS1986

Orbital flight simulation utility software unit specifications, revision 1

The HP PASCAL source code defines the specifications for a Utility Software Unit (USU) designed to support orbital flight simulators such as MANHANDLE and GREAS (General Research and Engineering Analysis Simulator). Besides providing basic input/output, mathematical, matrix, quaternion, and statistical routines for such simulators, one of the primary functions of the USU is to isolate all system-dependent codes in one well-defined compartment, thereby facilitating transportation of the simulations from one computer to another. Directives are given for the PASCAL compilers of the HP-9000 Series 200 Pascal 3.0 and the HP-9000 Series 500 HP-UX 5.0 operating systems that produce a single file of relocatable code from four separate files of source code. Three of the source code files are common to both operating systems. The fourth source code file (utilspif.I) contains all of the system-dependent PASCAL code for the USU. A fifth file of source code written in C is required to interface utilspif.I with the HP-UX I/O package. The Pascal 3.0 compiler directives and the driver source code for a unit rest program and counterparts for the HP-UX 5.0 operating system are given. The major portion of the unit test program source code is common to both operating systems. Unit test results from the Pascal 3.0 operating system and results from the HP-UX operating system are given.

Wilson, S. W.↗
NASA NTRS1991

Spatial orientation and dynamics in virtual reality systems - Lessons from flight simulation

Artificial representations of virtual worlds are becoming more common due to advances in the technology of image generation and display systems. Application areas include flight simulation, mission rehearsal, teleoperator systems, and virtual reality systems. System developers should be forewarned that some proportion of users will experience perceptual anomalies and symptoms of motion sickness as a result of travel through virtual space.

Mccauley, Michael E.↗
NASA NTRS1987

Measurement of human pilot dynamic characteristics in flight simulation

Fast Fourier Transform (FFT) and Least Square Error (LSE) estimation techniques were applied to the problem of identifying pilot-vehicle dynamic characteristics in flight simulation. A brief investigation of the effects of noise, input bandwidth and system delay upon the FFT and LSE techniques was undertaken using synthetic data. Data from a piloted simulation conducted at NASA Ames Research Center was then analyzed. The simulation was performed in the NASA Ames Research Center Variable Stability CH-47B helicopter operating in fixed-basis simulator mode. The piloting task consisted of maintaining the simulated vehicle over a moving hover pad whose motion was described by a random-appearing sum of sinusoids. The two test subjects used a head-down, color cathode ray tube (CRT) display for guidance and control information. Test configurations differed in the number of axes being controlled by the pilot (longitudinal only versus longitudinal and lateral), and in the presence or absence of an important display indicator called an 'acceleration ball'. A number of different pilot-vehicle transfer functions were measured, and where appropriate, qualitatively compared with theoretical pilot- vehicle models. Some indirect evidence suggesting pursuit behavior on the part of the test subjects is discussed.

Reedy, James T.↗
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.↗
NASA NTRS1995

Color Helmet Mounted Display System with Real Time Computer Generated and Video Imagery for In-Flight Simulation

NASA Ames Research Center and the US Army are developing the Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) using a Sikorsky UH-60 helicopter for the purpose of flight systems research. A primary use of the RASCAL is in-flight simulation for which the visual scene will use computer generated imagery and synthetic vision. This research is made possible in part to a full color wide field of view Helmet Mounted Display (HMD) system that provides high performance color imagery suitable for daytime operations in a flight-rated package. This paper describes the design and performance characteristics of the HMD system. Emphasis is placed on the design specifications, testing, and integration into the aircraft of Kaiser Electronics' RASCAL HMD system that was designed and built under contract for NASA. The optical performance and design of the Helmet mounted display unit will be discussed as well as the unique capabilities provided by the system's Programmable Display Generator (PDG).

Sawyer, Kevin↗
NASA NTRS1979

An in-flight simulator investigation of roll and yaw control power requirements for STOL approach and landing: Development of capability and preliminary results

A six-degree-of-freedom variable-response research aircraft was used to determine the minimum lateral-directional control power required for desirable and acceptable levels of handling qualities for the STOL landing approach task in a variety of simulated atmospheric disturbance conditions for a range of lateral-directional response characteristics. Topics covered include the in-flight simulator, crosswind simulation, turbulence simulation, test configurations, and evaluation procedures. Conclusions based on a limited sampling of simulated STOL transport configurations flown to touchdown out of 6 deg, 75 kt MLS approaches, usually with a sidestep maneuver are discussed.

Ellis, D. R.↗
NASA NTRS2006

An Experimental Study of the Effect of Out-of-the-Window Cues on Training Novice Pilots on a Flight Simulator

The effects of out-of-the-window cues on learning a straight-in landing approach and a level 360deg turn by novice pilots on a flight simulator have been investigated. The treatments consisted of training with and without visual cues as well as density of visual cues. The performance of the participants was then evaluated through similar but more challenging tasks. It was observed that the participants in the landing study who trained with visual cues performed poorly than those who trained without the cues. However the performance of those who trained with a faded-cues sequence performed slightly better than those who trained without visual cues. In the level turn study it was observed that those who trained with the visual cues performed better than those who trained without visual cues. The study also showed that those participants who trained with a lower density of cues performed better than those who trained with a higher density of visual cues.

Khan, M. Javed↗
NASA NTRS1975

A Standard Kinematic Model for Flight Simulation at NASA Ames

A standard kinematic model for aircraft simulation exists at NASA-Ames on a variety of computer systems, one of which is used to control the flight simulator for advanced aircraft (FSAA). The derivation of the kinematic model is given and various mathematical relationships are presented as a guide. These include descriptions of standardized simulation subsystems such as the atmospheric turbulence model and the generalized six-degrees-of-freedom trim routine, as well as an introduction to the emulative batch-processing system which enables this facility to optimize its real-time environment.

Mcfarland, R. E.↗