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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Frequency-Domain Deconvolution for Flight Dynamics Applications

A deconvolution method is presented for estimating input data from measured output data and a model of the dynamic process involved. The method uses an optimal Wiener filter for separating the measured data into signal and noise components, and a high-accuracy Fourier transform for inverting the model dynamics in the frequency domain. The method is an extension of optimal Fourier smoothing, and uses a technique to enhance the contrast between the signal and noise spectra in designing the Wiener filter. The deconvolution method was applied to simulation and flight test data for the purposes of removing unwanted distortions introduced by signal-conditioning filters and sensor dynamics, and for reconstructing turbulence inputs from measured sensor data. Results indicated hat the method performs well given good signal-to-noise levels and accurate models of the dynamic process.

Grauer, Jared A.↗
NASA NTRS2012

Flight Dynamics Modeling and Simulation of a Damaged Transport Aircraft

A study was undertaken at NASA Langley Research Center to establish, demonstrate, and apply methodology for modeling and implementing the aerodynamic effects of MANPADS damage to a transport aircraft into real-time flight simulation, and to demonstrate a preliminary capability of using such a simulation to conduct an assessment of aircraft survivability. Key findings from this study include: superpositioning of incremental aerodynamic characteristics to the baseline simulation aerodynamic model proved to be a simple and effective way of modeling damage effects; the primary effect of wing damage rolling moment asymmetry may limit minimum airspeed for adequate controllability, but this can be mitigated by the use of sideslip; combined effects of aerodynamics, control degradation, and thrust loss can result in significantly degraded controllability for a safe landing; and high landing speeds may be required to maintain adequate control if large excursions from the nominal approach path are allowed, but high-gain pilot control during landing can mitigate this risk.

Shah, Gautam H.↗
NASA NTRS1994

Flight Dynamics and Control of Elastic Hypersonic Vehicles Uncertainty Modeling

It has been shown previously that hypersonic air-breathing aircraft exhibit strong aeroelastic/aeropropulsive dynamic interactions. To investigate these, especially from the perspective of the vehicle dynamics and control, analytical expressions for key stability derivatives were derived, and an analysis of the dynamics was performed. In this paper, the important issue of model uncertainty, and the appropriate forms for representing this uncertainty, is addressed. It is shown that the methods suggested in the literature for analyzing the robustness of multivariable feedback systems, which as a prerequisite to their application assume particular forms of model uncertainty, can be difficult to apply on real atmospheric flight vehicles. Also, the extent to which available methods are conservative is demonstrated for this class of vehicle dynamics.

Chavez, Frank R.↗
NASA NTRS2009

Blended-Wing-Body Low-Speed Flight Dynamics: Summary of Ground Tests and Sample Results

A series of low-speed wind tunnel tests of a Blended-Wing-Body tri-jet configuration to evaluate the low-speed static and dynamic stability and control characteristics over the full envelope of angle of attack and sideslip are summarized. These data were collected for use in simulation studies of the edge-of-the-envelope and potential out-of-control flight characteristics. Some selected results with lessons learned are presented.

Vicroy, Dan D.↗
NASA NTRS2002

Preliminary Planar Formation-Flight Dynamics Near Sun-Earth L2 Point

A few space agencies are planning missions to the vicinity of the Sun-Earth L(sub 2) point, some involving a distributed space system of telescope spacecraft, configured in a plane about a hub. An improved understanding is developed of the relative motion of such objects in formation flight. The telescope equations of motion are written relative to the hub, in terms of the hub s distance from L(sub 2), and an analytical solution is developed, useful for performing orbit control analysis. A halo telescope orbit is investigated, with initial conditions selected to avoid resonance excitation. An example case of the resulting solution is presented.

Segerman, Alan M.↗
NASA NTRS1996

Solar and Heliospheric Observatory (SOHO) Flight Dynamics Simulations Using MATLAB (R)

This paper describes a study to verify onboard attitude control laws in the coarse Sun-pointing (CSP) mode by simulation and to develop procedures for operational support for the Solar and Heliospheric Observatory (SOHO) mission. SOHO was launched on December 2, 1995, and the predictions of the simulation were verified with the flight data. This study used a commercial off the shelf product MATLAB(tm) to do the following: Develop procedures for computing the parasitic torques for orbital maneuvers; Simulate onboard attitude control of roll, pitch, and yaw during orbital maneuvers; Develop procedures for predicting firing time for both on- and off-modulated thrusters during orbital maneuvers; Investigate the use of feed forward or pre-bias torques to reduce the attitude handoff during orbit maneuvers - in particular, determine how to use the flight data to improve the feed forward torque estimates for use on future maneuvers. The study verified the stability of the attitude control during orbital maneuvers and the proposed use of feed forward torques to compensate for the attitude handoff. Comparison of the simulations with flight data showed: Parasitic torques provided a good estimate of the on- and off-modulation for attitude control; The feed forward torque compensation scheme worked well to reduce attitude handoff during the orbital maneuvers. The work has been extended to prototype calibration of thrusters from observed firing time and observed reaction wheel speed changes.

Headrick, R. D.↗
NASA NTRS2024

Flight Dynamics and Navigation Performance of the BioSentinel Mission

BioSentinel was one of ten CubeSats launched by the Space Launch System (SLS) as part of the Artemis I campaign on 16 November 2022. A lunar flyby gave BioSentinel the needed energy to escape the Earth-Moon system into heliocentric space. The biological payload contains yeast cells designed to measure radiation in deep space beyond the reach of Earth’s magnetosphere. This paper discusses in detail the BioSentinel flight performance, as well as challenges and lessons learned prior to, and during the mission.

BioSentinel↗
NASA NTRS1993

A SIMULINK environment for flight dynamics and control analysis: Application to the DHC-2 Beaver. Part 1: Implementation of a model library in SIMULINK. Part 2: Nonlinear analysis of the Beaver autopilot

The design of advanced Automatic Aircraft Control Systems (AACS's) can be improved upon considerably if the designer can access all models and tools required for control system design and analysis through a graphical user-interface, from within one software environment. This MSc-thesis presents the first step in the development of such an environment, which is currently being done at the Section for Stability and Control of Delft University of Technology, Faculty of Aerospace Engineering. The environment is implemented within the commercially available software package MATLAB/SIMULINK. The report consists of two parts. Part I gives a detailed description of the AACS design environment. The heart of this environment is formed by the SIMULINK implementation of a nonlinear aircraft model in block-diagram format. The model has been worked out for the old laboratory aircraft of the Faculty, the De Havilland DHC-2 'Beaver', but due to its modular structure, it can easily be adapted for other aircraft. Part I also describes MATLAB programs which can be applied for finding steady-state trimmed-flight conditions and for linearization of the aircraft model, and it shows how the built-in simulation routines of SIMULINK have been used for open-loop analysis of the aircraft dynamics. Apart from the implementation of the models and tools, a thorough treatment of the theoretical backgrounds is presented. Part II of this report presents a part of an autopilot design process for the 'Beaver' aircraft, which clearly demonstrates the power and flexibility of the AACS design environment from part I. Evaluations of all longitudinal and lateral control laws by means of nonlinear simulations are treated in detail. The AACS design environment from part I proved to be a very useful tool for designing the control laws of the 'Beaver' autopilot within a very tight time-schedule. The autopilot design process itself will be used as a guideline for future AACS research at the Faculty of Aerospace Engineering. Flight tests of the 'Beaver' autopilot, done after evaluating the control laws in the SIMULINK package, proved to be quite successful. In the future, the AACS design package will evolve into a standardized, integrated design environment which can be applied to virtually any type of aircraft. The AACS design cycle will be shortened further by developing tools for automatically porting control laws from the MATLAB/SIMULINK environment to a piloted real-time flight simulator and the Flight Control Computers of the aircraft.

Flight Control System Design↗
NASA NTRS2008

NASA Langley's AirSTAR Testbed: A Subscale Flight Test Capability for Flight Dynamics and Control System Experiments

As part of the Airborne Subscale Transport Aircraft Research (AirSTAR) project, NASA Langley Research Center (LaRC) has developed a subscaled flying testbed in order to conduct research experiments in support of the goals of NASA s Aviation Safety Program. This research capability consists of three distinct components. The first of these is the research aircraft, of which there are several in the AirSTAR stable. These aircraft range from a dynamically-scaled, twin turbine vehicle to a propeller driven, off-the-shelf airframe. Each of these airframes carves out its own niche in the research test program. All of the airplanes have sophisticated on-board data acquisition and actuation systems, recording, telemetering, processing, and/or receiving data from research control systems. The second piece of the testbed is the ground facilities, which encompass the hardware and software infrastructure necessary to provide comprehensive support services for conducting flight research using the subscale aircraft, including: subsystem development, integrated testing, remote piloting of the subscale aircraft, telemetry processing, experimental flight control law implementation and evaluation, flight simulation, data recording/archiving, and communications. The ground facilities are comprised of two major components: (1) The Base Research Station (BRS), a LaRC laboratory facility for system development, testing and data analysis, and (2) The Mobile Operations Station (MOS), a self-contained, motorized vehicle serving as a mobile research command/operations center, functionally equivalent to the BRS, capable of deployment to remote sites for supporting flight tests. The third piece of the testbed is the test facility itself. Research flights carried out by the AirSTAR team are conducted at NASA Wallops Flight Facility (WFF) on the Eastern Shore of Virginia. The UAV Island runway is a 50 x 1500 paved runway that lies within restricted airspace at Wallops Flight Facility. The facility provides all the necessary infrastructure to conduct the research flights in a safe and efficient manner. This paper gives a comprehensive overview of the development of the AirSTAR testbed.

Jordan, Thomas L.↗
NASA NTRS2015

Summary of the First High-Altitude, Supersonic Flight Dynamics Test for the Low-Density Supersonic Decelerator Project

NASA's Low-Density Supersonic Decelerator Project is developing and testing the next generation of supersonic aerodynamic decelerators for planetary entry. A key element of that development is the testing of full-scale articles in conditions relevant to their intended use, primarily the tenuous Mars atmosphere. To achieve this testing, the LDSD project developed a test architecture similar to that used by the Viking Project in the early 1970's for the qualification of their supersonic parachute. A large, helium filled scientific balloon is used to hoist a 4.7 m blunt body test vehicle to an altitude of approximately 32 kilometers. The test vehicle is released from the balloon, spun up for gyroscopic stability, and accelerated to over four times the speed of sound and an altitude of 50 kilometers using a large solid rocket motor. Once at those conditions, the vehicle is despun and the test period begins. The first flight of this architecture occurred on June 28th of 2014. Though primarily a shake out flight of the new test system, the flight was also able to achieve an early test of two of the LDSD technologies, a large 6 m diameter Supersonic Inflatable Aerodynamic Decelerator (SIAD) and a large, 30.5 m nominal diameter supersonic parachute. This paper summarizes this first flight.

Clark, Ian G.↗
NASA NTRS1966

Mariner Mars 1964 flight dynamic data

Telemetry data in and around Mars spacecraft area analyzed for Mariner III and IV space probes by data from vibration transducers on payload and microphones on umbilical tower

TELEMETRY↗
NASA NTRS1972

The foundations of space biology and medicine. Volume 2: Ecological and physiological bases of space biology and medicine. Part 3: Effect on the organism of dynamic flight factors. Chapter 1: Principles of gravitational biology

The physical principles of gravitation are discussed, such as gravitational and intertial forces, weight and mass, weightlessness, size and scale effects, scale limits of gravitational effects, and gravity as a biogenic factor. The behavior of the accelerative force gravitation, is described. This law proposes and quantifies the mutual gravitational attraction existing between all bodies of matter, the force being proportional to the product of masses, and inversely related to the square of the distance separating them. Gravity orientation, chronic acceleration, and hematology are examined. Systematic responses, such as circulation and renal functions, are also considered, along with animal response to a decreased acceleration field and physiology of hyper- and hypodynamic fields.

Smith, A. H.↗
NASA NTRS1977

Calculated Hovering Helicopter Flight Dynamics with a Circulation Controlled Rotor

The influence of the rotor blowing coefficient on the calculated roots of the longitudinal and lateral motion was examined for a range of values of the rotor lift and the blade flap frequency. The control characteristics of a helicopter with a circulation controlled rotor are discussed. The principal effect of the blowing is a reduction in the rotor speed stability derivative. Above a critical level of blowing coefficient, which depends on the flap frequency and rotor lift, negative speed stability is produced and the dynamic characteristics of the helicopter are radically altered.

Johnson, W.↗
NASA NTRS1978

A static acoustic signature system for the analysis of dynamic flight information

The Army family of helicopters was analyzed to measure the polar octave band acoustic signature in various modes of flight. A static array of calibrated microphones was used to simultaneously acquire the signature and differential times required to mathematically position the aircraft in space. The signature was then reconstructed, mathematically normalized to a fixed radius around the aircraft.

Ramer, D. J.↗