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Viewing 151 to 180 of 61883
2010-10-17
Technical Paper
2010-36-0550
Aleksandras Jagniatinskas, Oleksandr Zaporozhets, Oleg Kartyshev, Boris Fiks
For assessment of the aircrafts noise impact on the community near to airports the acoustic calculations and measurements may be used. Obtained measurements results show ~1 dBA for LAeq coincidence with calculations results and allow to prepare correct database for practical use under ECAC method. While results of LAmax estimation still remain under investigation. These requirements are important first of all for aircraft, which are designed in FSU, Russian Federation and Ukraine. Their contribution to the aircraft noise impact in airports of FSU countries is still dominant, so their correct input data is still necessary.
2010-10-17
Technical Paper
2010-36-0547
Luiz Chamon, Giuliano Quiqueto, Sylvio Bistafa
Mechanical systems excited by vibratory point-sources tend to suffer from interference among axes, due to characteristics of the reproduction system or difficulties associated with the application of the excitation forces on the system's mass center. Thus, when it is necessary to excite the system independently in different directions, control techniques are needed for the correct reproduction of the desired signals. This work presents the developments for the reproduction of vibrations in two directions, on platforms employed as the base of seats of an aircraft cabin simulator. Each platform is independently excited by two orthogonal shakers, located in the geometrical center of the latter. Based on an evaluation of the degree of coupling between both orthogonal axes, signal processing solutions for the decoupling problem are proposed. Using SVD to diagonalize the transfer-function matrix, an independent base for the system was identified.
2010-10-17
Technical Paper
2010-36-0538
Mario Triches Jr., Micael G. V. do Carmo, Vinicius L. Gouveia
Without available direct measurements, the only method of assessing the impact of a completely new aircraft or power-plant design is to utilize a reliable prediction procedure. Such a procedure may be able to make use if a limited amount of directly relevant data, for instance, engine test data, or may have to rely entirely upon empirical component prediction procedures. Traditional aircraft noise prediction procedures based on engine static noise data are generally costly in time, since the engine source separation process is not a straightforward task, demanding several side routines to make it feasible. This paper attempts to present a new and simplified approach to assess community noise levels of a new aircraft design based on static engine noise data. The simplified procedure proposes an alternative to the complete engine source separation process, based on the definition of master parameters like jet noise cut-off frequencies, tonal frequencies and resultant broadband spectra.
2010-10-17
Technical Paper
2010-36-0546
Giuliano Quiqueto, Luiz Chamon, Sylvio Bistafa
In order to generate in-flight acoustic and vibration fields inside an aircraft cabin mock-up, an N&V simulator was developed. The preliminary work on the development, setup and characterization of the N&V simulator will be presented. Firstly, an overview of the system will be given, including the desired input signals, followed by the presentation of the control software, which was developed to simplify the operation of the system by end users during routine testing. Secondly, the set-up strategy to adjust the reproduction of levels and spectrum of both acoustic and vibration fields will be presented, along with comparative vibroacoustics results between the mock-up and original in-flight recordings. Finally, a discussion on different methods for adjusting the simulator reproduction by means of optimal filtering is made, and further developments are presented.
2010-10-17
Technical Paper
2010-36-0545
Fred Mendonca, Alex Read, Fabiano Imada, Vinicius Girardi
The transport industries face a continuing demand from customers and regulators to improve the acoustic performance of their products: reduce noise heard by passengers and passersby; avoid exciting structural modes. In both the aerospace and automotive areas, flow-induced noise makes a significant contribution, leading to the desire to understand and optimize it through the use of simulation. Historically, the need for time-consuming, computationally expensive transient simulations has limited the application of CFD in the field of acoustics. In this paper are described efficient simulation processes that, in some instances, remove the requirement for transient analyses, or significantly reduce the total process time through intelligent pre-processing. We will outline this process and provide both automotive and aerospace industrial examples, including analyses of highly complex geometries found in real life.
2010-10-17
Technical Paper
2010-36-0519
Jean-Pierre Coyette, Julien Manera
Abstract Numerical simulation techniques are widely used in automotive and aircraft sectors. The optimization of industrial products with respect to acoustic performance requires appropriate modeling strategies in order to handle various noise sources and different propagation paths. The present paper focuses on the application of finite element techniques (FE) to the solution of vibro-acoustic and aero-acoustic problems. State-of-the-art FE techniques are reviewed and illustrated by appropriate examples.
2010-10-17
Technical Paper
2010-36-0522
Dominique Collin
The X-NOISE Coordination Action, through its network structure and comprehensive workplan involving expert groups, scientific workshops, stakeholder seminars and a common information system, addresses the aircraft noise challenges set by the ACARE 2020 Vision. To this end, X-Noise undertakes the elaboration and coordination of research strategies, the dissemination of results and the integration of European research activities in the field of air transport related to noise. Over 4 years, the project has involved strong participation from European Union-based organizations as well as significant contribution from international partners, combining the complementary skills and expertise of industry, SMEs, universities and research establishments to cover the whole field of interest.
2010-10-17
Technical Paper
2010-36-0520
Delia Dimitriu, Dragos Munteanu, Octavian Pleter
This paper is assessing two methods that can be used in assessing the airport noise capacity when new operational practices are implemented at a certain airport. The example given is CDA-continuous descent approach implemented at Bucharest Henri Coanda International airport in Romania. A review of the main operational practices related to CDO (Continuous Descent Operations) with relevance for noise and emissions reduction, shows the importance of working in a team when implementing new operational practices, as well as the need to access data either through FDR (flight data recorder) or from measurements. - The example selected explains the difficulties one can have to extract FDR data. Although the authors of this paper benefitted from FDR from TAROM, the Romanian national airline, it was difficult to be extracted, so the assessment of the airport noise capacity focused on monitoring and measurements undertaken under the flight path.
2010-10-17
Technical Paper
2010-36-0526
Jerome E. Manning, Chadwyck T. Musser, Alice Botteon Rodrigues
Statistical Energy Analysis (SEA) is an established high-frequency analysis technique for generating acoustic and vibration response predictions in the automotive, aerospace, machinery, and ship industries. SEA offers unique NVH prediction and target-setting capabilities as a design tool at early stages of vehicle design where geometry is still undefined and evolving and no prototype hardware is available yet for testing. The exact frequencies at which SEA can be used effectively vary according to the size and the amount of damping in the vehicle subsystems; however, for automotive design the ability to predict acoustic and vibration responses due to both airborne and structure-borne sources has been established to frequencies of 500 Hz and above. This paper presents the background, historical use, and current industrial applications of structure-borne SEA. The history and motivation for the development of structure-borne SEA are discussed.
2010-10-17
Technical Paper
2010-36-0506
Micael G. V. do Carmo, Julio R. Meneghini
The Brazilian Silent Aircraft Program (Programa "Aeronave Silenciosa) is an initiative of six Brazilian Universities and Institutes (USP-Poli "University of Sao Paulo - Polytechnic School, USP/EESC - University of Sao Paulo - Sao Carlos Engineering School, UFSC - Federal University of Santa Catarina, UFU - Federal University of Uberlandia, UnB - University of Brasilia and IAE - Brazilian Institute of Aeronautics and Space) together with Embraer to develop methodologies and solutions for the aircraft external noise problem. The main goal of this initiative is to study and develop methodologies that will allow estimation of aircraft noise generation and propagation through three main approaches: numerical simulation (CAA), analytical and semi-empirical models, and wind tunnel and flight tests.
2010-10-17
Technical Paper
2010-36-0513
Bruno Dal'Carobo, Ricardo Fensterseifer
In the last decades, the evolution of aircraft design has been influenced so much by aeroelasticity, and in particular, flutter. Flutter is a characteristic aircraft phenomenon of external excited vibrations, working on the resonance gap, which involves the structural airplane elements and if it was not reported can be the source of critical failures of wings or control surfaces. The present paper will give a general vision about flutter phenomenon in airplanes wings, specifically on planes of the aero design, which ones usually disregards this kind of study. However, this study includes an approach to explain the materials and methods used to find the results. Using data from aero design planes its possible presents how a mechanical engineer can use considerations of flutter to the project and analysis.
2010-10-17
Technical Paper
2010-36-0514
Pieter Sijtsma
An introduction is given of phased array beamforming techniques for locating acoustic sources. Starting from basic principles, the Conventional Beamforming technique is described. It is explained how this technique can be applied to wind tunnel measurements. Further, a number of advanced array processing techniques are discussed. One chapter is devoted to the array processing technique for the location of moving sources. This technique can be applied to rotating sources, for example on wind turbine blades, and to source location on aircraft flying over a microphone array.
1999-10-19
Technical Paper
1999-01-5632
Gregor A. Dirks
A general outline of the motivation of the research project „Technology Navigator“ and the contents of work is given, together with details of the methodology under development. The impact of the introduction of new technology is analyzed from the view of an aircraft manufacturer, in order to derive a methodology for the support of technology scheduling. Important features of this methodology are the consideration of the whole family of aircraft addressed, the planning of technology readiness and corresponding investment and it’s impact on the cash flow curve. Where forecasts or other uncertainties are involved a statistical approach is chosen.
1999-10-19
Technical Paper
1999-01-5629
Martin Kraus, Rudolf Heinzinger, Hans-Christoph Oelker
Integration of ground-based testing into the airborne testing process is presented in terms of an advanced test and analysis concept. Based on the discussion, that running a simulator is less expensive than performing a test flight, means of combining both methodologies are being presented and discussed. The idea is to perform selected tests on ground-based facilities under test flight conditions. This is called Virtual Flight Testing. For explanation of this idea an example is given and a representative result is presented. Another main pillar of this advanced test and analysis concept is on-line analysis. A recent tool for this purpose is on-line simulation, which is introduced with a brief overview together with an illustrative example. The paper gives an introduction into DASA’s efforts to increase efficiency of the testing process. The main goal is an early feedback of test information into the design process in order to improve this process.
1999-10-19
Technical Paper
1999-01-5631
Michelle R. Kirby, Dimitri N. Mavris
An evolved version of the Technology Identification, Evaluation, and Selection (TIES) method is presented that provides techniques for quantifying technological uncertainty associated with immature technologies. Uncertainty in this context implies forecasting. Forecasting the impact of immature technologies on a system is needed to provide increased knowledge to a decision-maker in the conceptual and preliminary phases of aircraft design. The increased knowledge allows for proper allocation of company resources and program management. The TIES method addresses the milestones encountered during a technology development program, the sources of uncertainty during that development, a potential method for bounding and forecasting the uncertainty, and a means to quantify the impact of any emerging technology. A proof of concept application was performed on a High Speed Civil Transport concept due to its technically challenging customer requirements.
1999-10-19
Technical Paper
1999-01-5641
Dimitri N. Mavris, Songtao Qiu
One of the most essential contributors in the aircraft sizing and synthesis process is the creation and utilization of accurate drag polars. An improved general procedure to generate drag polars for conceptual and preliminary design purposes in the form of Response Surface Equations is outlined and discussed in this paper. This approach facilitates and supports aerospace system design studies as well as Multi-disciplinary Analysis and Optimization. The analytically created Response Surface Equations replace the empirical aerodynamic relations or historical data found in sizing and synthesis codes, such as the Flight Optimization System (FLOPS). These equations are commonly incorporated into system level studies when a configuration falls beyond the conventional realm. The approach described here is a statistics-based methodology, which combines the use of Design of Experiments and Response Surface Method (RSM).
1999-10-19
Technical Paper
1999-01-5639
Mark A. Hale, Dimitri N. Mavris, Dennis L. Carter
The Conceptual Aerospace Systems Design and Analysis Toolkit (CASDAT) provides a baseline assessment capability for the Air Force Research Laboratory. The historical development of CASDAT is of benefit to the design research community because considerable effort was expended in the classification of the analysis tools. Its implementation proves to also be of importance because of the definition of assessment use cases. As a result, CASDAT is compatible with accepted analysis tools and can be used with state-of-the-art assessment methods, including technology forecasting and probabilistic design.
1999-10-19
Technical Paper
1999-01-5645
Alexander V. Firsov, Oleg A. Yakimenko
The present paper deals with a general ideology, hardware architecture, and some aspects of software filling of the mobile adaptive simulator aircraft of an aircraft. This simulator provides the pilotage and combat skills maintenance, pre-flight training and forthcoming, flight mission image formation on the board of his “native” aircraft with “native” habitual cockpit environment and controls. Proposed idea has been already realized and demonstrated during International Aviaspace saloon in Zhukovskiy, Russia in 1997 and 1999 on board of the modern combat aircraft. The paper describes also the results of preliminary testing of this analogue of embedded training system, contains the pilots’ and experts’ estimates. In conclusion authors discuss a helpfulness of such system and its economical efficiency.`
1999-10-19
Technical Paper
1999-01-5658
Paul Pencikowski
Given the rapidly rising complexity of advanced-development aircraft and the diminishing experience pool of crewstation designers, a requirement exists for the implementation of crewstation development tools. These tools must support real-time simulation, advanced displays, and empirical data collection. Northrop’s Advanced Crewstation Integration Cockpit (ACIC) introduces full and rapid reconfigurability to a comprehensive aerodynamic, threat, sensor and weapons system simulation presented to the pilot on conventional or advanced-design displays. All controls and displays are reprogrammable, relocatable, and reconfigurable in their size, type of action and graphical attributes. Development capability for expert systems, sensor fusion, and data collection requirements are provided for. This standalone system, operating in real time, is unique in its ability to perform high-utility simulation at low cost.
1999-10-19
Technical Paper
1999-01-5659
R. Kruk, N. Link, L. Reid, S. Jennings
The Enhanced/Synthetic Vision System (E/SVS) is a Technology Demonstrator (TD) project supported by the Chief, Research and Development of the Canadian Department of National Defence. E/SVS displays an augmented visual scene to the pilot that includes three separate image sources: a synthetic computer - generated terrain image; an enhanced visual image from an electro-optical sensor (fused as an inset); and aircraft instrument symbology, all displayed to the pilot on a Helmet Mounted Display (HMD). The synthetic component of the system provides a 40 degree vertical by 80 degree horizontal image of terrain and local features. The enhanced component digitizes imagery from electro-optic sensors and fuses the sensor image as an inset (20 degrees by 25 degrees) within the synthetic image. Symbology can be overlaid in any location within the synthetic field-of-view and may be head, aircraft, target or terrain referenced.
1999-10-19
Technical Paper
1999-01-5654
Barth W. Shenk
An empirically based, analytical tool for calculating lift, drag and pitching moment of tilting wing configurations is presented, and used to develop the general characteristics of the Compound Tilting Wing (CTW), a variation on the conventional tilting wing configuration. The CTW utilizes an inboard leading edge extension, which acts as a canard when the wing tilts to augment pitch control during low speed operations and conforms to the wing at zero tilt. This scheme allows the designer more degrees of freedom for overall configuration layout and propulsion system integration for STOL design.
1999-10-19
Technical Paper
1999-01-5657
Ian A. Maddock
Flying wing aircraft predate the First World War. The flying wing theoretically offers both aerodynamic efficiency and structural simplicity. Early efforts to develop the flying wing concept led to an increased interest in tailless and semi-tailless aircraft that eventually led to delta wings and swept wing planforms. Early flying wings were plagued by stability and control problems that have not been fully addressed until recently. The flying wing approach, however, still appears to be suitable only for aircraft that do not need to have high maneuverability and agility capabilities, such as long-range bombers or perhaps large transports. This paper surveys the long history of attempts to create flying wing aircraft.
1999-10-19
Technical Paper
1999-01-5607
R Bruce Lumsden, Gareth D Padfield, Carole D Braby-Deighton
The paper takes a total systems approach to the human factors challenges at the helicopter-ship dynamic interface. It examines the problems of operating large helicopters from small ships in all weather conditions from the start of the mission to completion with due emphasis on the launch and recovery phases. Research taking place at DERA Bedford in support of current and future naval operations is outlined. Although the prime focus is Royal Navy Anti-submarine Warfare operations, the paper also considers present and future maritime and marinised helicopter types. The paper is written from the perspective of developing requirements and reducing risk by demonstrating technical solutions. The main focus of the paper is the recovery from completion of task to securing in the ship’s hangar. It addresses the aspects of automatic flight path management and flight control systems and the role of automation during the recovery process, particularly in the case of the single pilot aircraft.
1999-10-19
Technical Paper
1999-01-5606
A. Leger, C. Gardelle, G. Bruniaux
Abstract Advanced binocular Helmet Mounted Displays (HMD) capable of bisensor operation (I2 tubes and video images) with overlaid symbology have been developed for military use in various helicopters. Extensive flight testing of such helmets, as the French TOPOWL®, have provided so far a considerable amount of data relatively to Night Vision System design and use. Design options allowing improved mass and Center of Gravity in regard of classical NVG, as folded optics and visor projection, have been shown to give very effective results. Performance in various flight conditions, including fog, snow and obstacles, has been quite thoroughly investigated. Training issues with I2 and head-steered thermal imagery have also been addressed during test flight. Lessons learned from test flight open interesting possibilities for further use of such systems in civilian rotorcraft operation, provided acceptably low cost solutions could be achieved.
1999-10-19
Technical Paper
1999-01-5605
Jean H. Slane, Robert C. Winn
If an airplane crashes, the recorded radar data can be used to reconstruct a time history of the airplane’s calibrated airspeed, load factor, excess thrust, bank angle, etc. Previous work on this problem has used a rectilinear approach to the calculations involved in the flight parameter reconstruction. The rectilinear approach gives excellent results for relatively straight flight; however, it routinely underestimates the airspeed and the bank angle when the airplane is maneuvering. In the present study, the authors present a curvilinear approach to flight parameter reconstruction that addresses this shortcoming. The analysis presented shows that the curvilinear approach is a far superior tool than the rectilinear approach for the reconstruction of maneuvering flight including steep turns and high-speed spirals.
1999-10-19
Technical Paper
1999-01-5611
Oleg A. Yakimenko
The present paper considers the general aspects and mathematical foundation of the subsystem of on-board universal pilot’s support system, which provides pilot’s control actions support during more or less long-term maneuvers, such as take-off and climbing, flight on a route, surface-based target attack (in case of military aircraft), descent and landing via shortcut-time on-board optimization of spatial trajectories and their head-up display visualization in the view of “road-in-the-sky” image for further tracking in “director with sight” regime or (semi) automatic mode. There are mentioned briefly the main ideas of two specially designed for this purpose “fast” modifications of the direct method of calculus of variations. One (for short-term trajectories with strong restrictions on controls) based on 5th-7th order polynomial approximation; the second (for flight on a route) based on spline approximation.
1999-10-19
Technical Paper
1999-01-5610
Myrza Tjondronegoro, Kamran Rokhsaz, James E. Steck
In nonlinear cases, the SDG method requires multidimensional search procedures. However, in linear cases only one-dimensional search procedures are required to identify the critical gust load conditions. In this study the application of the backpropagation ANN method as a multi-dimensional modeling tool has been proposed to model or identify the global and local extrema of one-dimensional gust load responses. The maximum and minimum response values of ramp-step input gust profiles were considered to investigate the ANN modeling capability and effectiveness. The actual SDG analysis for nonlinear cases was hypothesized to be performed over a large and sparse domain, therefore the ANN could be trained to quickly identify the region of the domain containing the global extrema. The SDG analysis, then, could be concentrated on a smaller region thereby reducing computation time.
1999-10-19
Technical Paper
1999-01-5609
Richard L. Newman
In recent years, helicopter flight and mission information has migrated from conventional round mechanical dials mounted on the instrument panel to software-dependent head-mounted displays capable of showing many types of information. Test and evaluation techniques have not progressed commensurate with display technology. A formal test and evaluation program is proposed to ensure that new information displays support the pilot’s flight tasks. An outline of test requirements is presented for use in future flight display programs.
1999-10-19
Technical Paper
1999-01-5608
E. Theunissen, G. Sachs
The selection of the design parameters of a perspective flightpath display must take into account the operational capabilities of the vehicle to be controlled. As a result, designs of perspective flightpath displays that have been optimized for fixed-wing aircraft may need to be modified in order to be useful for advanced approach procedures with tiltrotors. This paper discusses potential changes that are required as a result of the different range of flightpath angles used in approach trajectories and the different range of velocities.
1999-10-19
Technical Paper
1999-01-5619
Richard M. Wood, Steven X. S. Bauer
A 1990 research program that focused on the development of advanced aerodynamic control effectors (AACE) for military aircraft has been reviewed and summarized. Data are presented for advanced planform, flow control, and surface contouring technologies. The data show significant increases in lift, reductions in drag, and increased control power, compared to typical aerodynamic designs. The results presented also highlighted the importance of planform selection in the design of a control effector suite. Planform data showed that dramatic increases in lift (> 25%) can be achieved with multiple wings and a sawtooth forebody. Passive porosity and micro drag generator control effector data showed control power levels exceeding that available from typical effectors (moving surfaces). Application of an advanced planform to a tailless concept showed benefits of similar magnitude as those observed in the generic studies.
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