Experimental Flight Data Research Articles

Targeted driving using visual tracking on Mars: From research to flight

AbstractThis paper presents the development, validation, and deployment of the visual target tracking capability onto the Mars Exploration Rover (MER) mission. Visual target tracking enables targeted driving, in which the rover approaches a designated target in a closed visual feedback loop, increasing the target position accuracy by an order of magnitude and resulting in fewer ground‐in‐the‐loop cycles. As a result of an extensive validation, we developed a reliable normalized cross‐correlation visual tracker. To enable tracking with the limited computational resources of a planetary rover, the tracker uses the vehicle motion estimation to scale and roll the template image, compensating for large image changes between rover steps. The validation showed that a designated target can be reliably tracked within several pixels or a few centimeters of accuracy over a 10‐m traverse using a rover step size of 10% of the target distance in any direction. It also showed that the target is not required to have conspicuous features and can be selected anywhere on natural rock surfaces excluding rock boundary and shadowed regions. The tracker was successfully executed on the Opportunity rover near Victoria Crater on four distinct runs, including a single‐sol instrument placement. We present the flight experiment data of the tracking performance and execution time. © 2009 Wiley Periodicals, Inc.

動力付パラグライダーの非線形モデル

This paper presents a nonlinear dynamic model of a powered paraglider (PPG). The PPG is composed of a canopy and a payload with a propelling unit. The canopy is connected with the payload at two points. The model has been derived as a state vector equation under the assumption that the canopy has six degrees of freedom (DOF) and the payload has two DOF of pitching and yawing motions relative to the canopy. Friction at the connecting points between the canopy and the payload is taken into account. Time responses of the PPG without thrust have been computed using the model and the results are compared with flight experiment data. Simulation of a level flight with thrust has also been conducted.

Simulation of a spinstabilised sports disc

The spin-stabilised sports disc, more commonly known as the Frisbee, is used for a variety of recreation and sporting activities. Frisbees have unique flying characteristics compared to other sports projectiles because they depend on spin for stability during flight and, at typical launch speeds, aerodynamic lift is greater than or equal to the weight of the disc. In this paper, a six degree of freedom mathematical model of a spinning disc wing is developed and a simple analytical expression derived for the disc roll rate in straight and level flight. It is shown that dimensionless disc trajectories will be similar for similar values of a parameter based on the ratio of the disc static margin to the disc advance ratio. The mathematical model is implemented as a simulation in Matlab using steady model parameters obtained from wind tunnel tests and unsteady parameters from flight tests. Simulation results are shown to be in reasonable agreement with limited available experimental flight data. The effect of launch conditions has been investigated using a series of numerical experiments. It is found that flight path curvature in the horizontal plane increases with decreasing advance ratio, as expected. Pitch angles at launch for maximum range and maximum duration are approximately 10° and 20° respectively. Also, the locus of disc landing position as a function of launch roll angle has been shown to be an ‘S’ shaped curve, with the straightest flight occurring for an initial roll angle of-6°. Finally, the simulation has been extended to include the effects of hypothetical control inputs, enabling simulation of novel Frisbee manoeuvres.

Small Aircraft Transportation System Higher Volume Operations Flight Experiment

This paper summarizes findings from the Small Aircraft Transportation System Higher Volume Operations Flight Experiment. The higher volume operations concept improves efficiency at nontowered, nonradar airports in instrument meteorological conditions. The success of the higher volume operations concept is based on pilot acceptability as determined through objective and subjective assessments when compared with the procedural control operations in use today at nontowered, nonradar-controlled airfields in instrument meteorological conditions. Flight experiment data indicate that the concept is viable. The experiment, flown on a general aviation aircraft, used a subset of the Higher Volume Operations Simulation Experiment scenarios and evaluation pilots to validate the simulation experiment results. Results reveal that all 12 low-time instrument-rated pilots preferred Small Aircraft Transportation System Higher Volume Operations when compared with current procedural separation operations. These pilots also flew the higher volume operations procedures safely and proficiently without additional workload in comparison to today's system. Detailed results of pilot flight technical error and their subjective assessments of workload and situation awareness are presented.

Aircraft parameter estimation using output-error methods

Certification requirements, optimization and minimum project costs, design of flight control laws and the implementation of flight simulators are among the principal applications of inverse problem applications in the aeronautical industry. The problem of aircraft identification and parameter estimation demands for accurate mathematical model of the aerodynamics and adequate experimental flight data gathering and processing. The aircraft dynamic modeling is characterized by aerodynamic and control derivatives whose values can be directly determined from flight test data. This work describes the application of the output-error method using the Nelder–Mead (NM) and Levenberg–Marquardt (LM) algorithms to obtain the aerodynamic and control derivatives of a regional jet aircraft. Unlike others identification methods based on equation-error the output-error method gives unbiased parameter estimation in the presence of measurement noise. In this work, experimental results for estimation of the lateral directional aerodynamic derivatives, using flight test data provided by EMBRAER, are presented.

Methodology for fatigue life assessment of the structural integrity of fighter aircraft

ABSTRACTThis work describes the present methodology used on Portuguese Air Force (PoAF) aircrafts for fatigue life assessment to maintain its structural integrity. This methodology uses experimental flight data collected by airborne instrumentation systems. The recorded data are analysed for the prediction of the crack growth of defects at critical components of the aircraft and this information is then used for planning non‐destructive inspections, maintenance, logistical support and operational usage of the various fleets. This methodology is exemplified by one application on DASSAULT/DORNIER ALPHA‐JET aircraft.

Micro-gravity experiment of a space robotic arm using parabolic flight

We conducted a micro-gravity flight experiment on a space robotic arm, which is a part of the Reconfigurable Brachiating space Robot (RBR) unit arm developed by the authors. We used a 4-d.o.f. arm and an end-effector in the experiment. The airplane (MU-300) generates the micro-gravity environment for approximately 20 s in parabolic flight operation. After the flight, we conducted the corresponding ground experiments, and obtained the data of the motor current, servo control characteristics and manipulation performances, which were compared with the flight experiment data. Then, we conducted the numerical analysis of the 4-d.o.f. RBR arm based on the experiment results. In the analysis, we investigated feasibility of simulation model and identified model parameters. In this paper, we report the results of the flight experiments and numerical analysis.

On‐line learning neural networks for sensor validation for the flight control system of a B777 research scale model

AbstractThis paper focuses on the analysis of a scheme for sensor failure, detection, identification and accommodation (SFDIA) using experimental flight data of a research aircraft model. Recent technical literature has shown the advantages of time‐varying estimators and/or approximators. Conventional approaches are based on different versions of observers and Kalman filters while more recent methods are based on different approximators based on neural networks (NNs). The approach proposed in the paper is based on the use of on‐line learning nonlinear neural approximators.The characteristics of three different neural architectures were compared through different sensor failures. The first architecture is based on a multi layer perceptron (MLP) NN trained with the extended back propagation algorithm (EBPA). The second and third architectures are based on a radial basis function (RBF) NN trained with the minimal resource allocating network (MRAN) and extended‐MRAN (EMRAN). The MRAN and EMRAN algorithms have recently been developed for RBF networks and have shown remarkable learning capabilities at a fraction of the memory requirements and computational effort typically associated with conventional RBF NNs.The experimental data for this study are flight data acquired from the flight‐testing of a $$1 \over 24$$th semi‐scale B777 research model designed, built, and flown at West Virginia University (WVU). Copyright © 2002 John Wiley & Sons, Ltd.

Integrated Energy Method for Propulsion Dynamics Analysis of Air-Pressurized Waterjet Rocket.

The launching of a waterjet rocket has been a very popular idea in recent years. Its basic propulsion principle makes use of the high-pressurized air inside the rocket’s main body to swiftly expel the water out of the nozzle and thus generate thrust. The waterjet rocket is characterized with nature, interest, combustionlessness, environmental friendliness, simplicity, and minimal cost. Moreover, it is a very good science model for propulsion analysis, design, experiment, and education because of an abundance of easily adjustable key parameters. This model also features separately stored energy and mass of the propellant, in contrast to a conventional rocket. However, related literature shows that no in-depth theoretical analysis of the waterjet rocket has been attempted for various reasons. In this research, the propulsion dynamics of a waterjet rocket is analyzed by simultaneously solving the momentum and the newly derived generalized power equations to predict its flight histogram, computationally, and convolutionally. This integrated energy approach synthesizes the internal and external dynamics analyses together and ingeniously takes full advantage of the clear power supply of pressurized air in a waterjet rocket. The analysis results are generally agreeable with the experimental flight data. While the new power equation herein gives a complete spectrum of physical parameters to be manipulated, there will be wider room in quest of better rocket propulsion performance, especially through the heuristic research of this versatile but affordable waterjet rocket.

Neural Network Research on Validating Experimental Tilt-Rotor Performance

Results from a neural network validation study with full-scale XV-15 tilt-rotor experimental hover and forward flight data are presented. Two test data bases, acquired during separate tests conducted at NASA Ames, were used. These two isolated XV-15 rotor test data bases were: the 80by 120-Foot Wind Tunnel hover and forward flight test data base, and secondly, an outdoor hover test data base. For this neural-network-based data validation study, the objective associated with the wind tunnel test data was: obtain neural network representations, conduct data quality checks, and demonstrate sensitivity to test conditions. Neural networks were successfully used to represent and assess the quality of full-scale tilt-rotor hover and forward flight performance test data. The neural networks accurately captured tilt-rotor performance at steady operating conditions and it was shown that the wind tunnel forward flight performance test data were generally of very high quality. The second objective, using outdoor hover test data, was to formulate and implement a neural-network-based wind correction procedure. Compared to existing, momentum-theorymethod based wiad corrections to outdoor hover performance, the present neural-network-procedure-based corrections were better. The present wind corrections procedure, based on a well-trained neural network, captured physical trends present in the outdoor hover test data that had been missed by the existing, momentum-theory-based method. Copyright © 1998 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under Title 17, U.S. Code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental Purposes. All other rights are reserved by the copyright owner. A a

Analysis of Supercritical Startup Behavior for Cryogenic Heat Pipes

A theoretical analysis was conducted to describe the startup process from the supercritical state for axially grooved cryogenic heat pipes. Using an approximation method, a heat-balance integral solution was developed to predict the rewetting velocity, liquid front position, and transient axial temperature distributions for axially grooved cryogenic heat pipes. The developed model assumes an initially uniform axial temperature distribution and divides the startup process into two characteristic regions, based on whether a liquid column is established in the condenser region. The predicted transient temperature profiles of two cryogenic oxygen heat pipes were in good agreement with previous experimental microgravity flight data. Nomenclature A = coefficient defined in Eq. (12) Af = cross-sectional area of the working fluid AI = cross-sectional area of the liquid channel As = cross-sectional area of the heat-pipe wall B = coefficient defined in Eq. (12) Ce = effective heat capacity c - specific heat D = coefficient defined in Eq. (12) Dh = hydraulic diameter E = thermal energy F = force h = groove thickness hfg = latent heat of liquid-vapor phase change k = thermal conductivity La = length of adiabatic section Lc = length of condenser Le = length of evaporator P = internal pressure Pc = critical pressure Pr = reduced pressure R = gas constant Re = Reynolds number r = capillary radius T = temperature Tc = critical temperature Tcond = condenser temperature Tr = reduced temperature 7*0 = initial temperature t - time U = liquid mean velocity Ur = liquid rewetting velocity v = specific volume of vapor w = groove width z = compressibility factor ae = effective heat diffusivity j8 = coefficient defined in Eq. (3) 8 = penetration depth e = liquid layer length

Engineering aerodynamic heating method for hypersonic flow

A capability to calculate surface heating rates has been incorporated in an approximate three-dimensional inviscid technique. Surface streamlines are calculated from the inviscid solution, and the axisymmetric analog is then used along with a set of approximate convective-heating equations to compute the surface heat transfer. The method is applied to blunted axisymmetric and three-dimensional ellipsoidal cones at angle of attack for the laminar flow of a perfect gas. The method is also applicable to turbulent and equilibrium-air conditions. The present technique predicts surface heating rates that compare favorably with experimental (ground-test and flight) data and numerical solutions of the Navier-Stokes (NS) and viscous shock-layer (VSL) equations. The new technique represents a significant improvement over current engineering aerothermal methods with only a modest increase in computational effort.

Helicopter rotor speed effects on farfield acoustic levels

The design of a helicopter is based on an understanding of many parameters and their interactions. For example, in the design stage of a helicopter, the weight, engine, and rotor speed must be considered along with the rotor geometry when considering helicopter operations. However, the relationship between the noise radiated from the helicopter and these parameters is not well understood, with only a limited set of model and full-scale field test data to study. In general, these data have shown that reduced rotor speeds result in reduced farfield noise levels. This paper will review the status of a recent helicopter noise research project designed to provide flight experimental data to be used for further understanding of helicopter rotor speed effects on farfield acoustic levels. Preliminary results will be presented relative to tests conducted with a McDonnell Douglas Helicopter Company model 500E helicopter operating with the rotor speed as the control variable over the range from 103% N2 to 75% N2 and the forward speed maintained at a constant value of 80 knots.

Theoretical design of acoustic treatment for noise control in a turboprop aircraft

An analytical procedure has been developed for design of acoustic treatment for cabin noise control of light aircraft. Using this approach acoustic add-on treatments capable of reducing the average noise levels in the cabin by about 17 dB from the untreated condition are developed. The added weight of the noise control package is about 2% of the total gross takeoff weight of the aircraft. The analytical model uses modal solutions wherein the structural modes of the sidewall and the acoustic modes of the receiving space are accounted for. The input noise spectral levels are selected utilizing experimental flight data. The add-on treatments include aluminum honeycomb panels, constrained layer damping tape, porous acoustic materials, noise barriers, limp trim panels, and tuned dampers. To reduce the noise transmitted through the double-wall aircraft windows to acceptable levels, changes in the design of the aircraft window are recommended.

An improved prediction method for the noise generated in flight by circular jets

A semi-empirical model for predicting the noise generated by jets exhausting from circular nozzles is presented and compared with small-scale static and simulated-flight data. The present method is an updated version of that part of the original NASA Aircraft Noise Prediction Program (1974) relating to circular jet noise. The earlier method has been shown to agree reasonably well with experimental static and flight data for jet velocities up to ∼ 520 m/s. The poorer agreement at higher jet velocities appeared to be due primarily to the manner in which supersonic convection effects were formulated. The purely empirical supersonic convection formulation is replaced in the present method by one based on theoretical considerations. Other improvements of an empirical nature have been included based on model-jet/free-jet simulated-flight tests. The effects of nozzle size, jet velocity, jet temperature, and flight are included.

Data Analysis Methodology for Day/Night Inflight Tactical Navigation

Nap-of-the-earth helicopter navigation, both at night and during the day, is essential to the Army's mission. Navigation performance, defined as the probability of navigating along a prescribed route or route segment without deviation, is a function of many factors including map and terrain types. Determination of the effects of these factors is important information for predicting performance of Army navigators, identifying factors critical to navigation, evaluating the probability of navigation success along a route and developing training aids. The purpose of the research work reported here was to analyze NOE flight experiment data to develop that information. This paper contains results from analyses of helicopter NOE navigation data to determine the probability of navigation success along a route as a function of terrain type, to develop a means of determining route difficulty, and to develop a method of scoring student performance.

An improved method for predicting the effects of flight on jet mixing noise

An improvement to the NASA method (1976) for predicting the effects of flight on jet mixing noise has been developed. The earlier method has been shown to agree reasonably well with experimental flight data for jet velocities up to about 520 m/s (∼1700 ft/s). The poorer agreement at high jet velocities appeared to be due primarily to the manner in which supersonic convection effects were formulated. The purely empirical supersonic convection formulation of the earlier method has now been replaced by one based on theoretical considerations. Other improvements of an empirical nature have been included based on model-jet/free-jet simulated flight tests. This report presents the new prediction method and comparisons with experimental data obtained from the Bertin Aerotrain with a J85 engine, the DC-10 airplane with JT9D engines, and the DC-9 airplane with refanned JT8D engines. It is shown that the new method agrees better with the data base than either the earlier NASA method or a recently proposed SAE method.

ATS-6 Solar Cell Flight Experiment After 325 Days in Synchronous Orbit

Preliminary Applications Technology Satellite-6 (ATS-6) solar cell flight experiment data through the first 325 days in synchronous orbit is present. The experiment is transmitting data on 16 different solar cell/cover glass configurations. The experiment is designed to study the effect of this orbit on select solar cells and cover glass parameters such as solar cell thickness and base resistivity, cover glass thickness variation, new cover and adhesive processes and materials such as 7940 and 7070 integral covers and the fluorinated ethylene propylene (FEP) covers, the COMSAT "violet" cell, and backside irradiation effects. The in-spece solar cell data indicate short circuit currents are higher by 1 to 8 percent than measurements made with solar simulations; maximum power varied between -1 to +6 percent . Degradation of /sc due to ultraviolet effects was determined to be about 2 percent after 50 days in orbit. All cells performed well through 325 days in orbit, except the FEP-covered cells, which appear to have increased their rate of degradation during the first eclipse season.

Pioneer 10 observations of the solar wind interaction with Jupiter

Pioneer 10 Plasma Analyzer experiment flight data during the Jupiter flyby are presented. The observations show that the interaction of Jupiter's magnetic field with the solar wind is similar in many ways to that at earth, but the scale size is over 100 times larger. Jupiter is found to have a detached standing bow shock wave of high Alfven Mach number. Jupiter has a prominent magnetopause which deflects the magnetosheath plasma and excludes its direct entry into the Jovian magnetosphere. The sunward hemisphere of Jupiter's outer magnetosphere is found to be highly inflated with thermal plasma and a high beta region which is highly responsive to changes in solar wind dynamic pressure. Observational arguments are presented which tend to discount a thin disklike magnetosphere but, rather, favor a Jovian magnetosphere, albeit probabily considerably flattened as compared to the earth's magnetosphere, yet still with reasonable thickness. Results concerning the shock jump conditions, the magnetosheath flow field and inferred internal magnetospheric plasma are presented.