bluuebunny/crossref_metadata_2025_split huggingface dataset:
A turbulence criterion for safe helicopter operations to offshore installations
Authors: Rowe S. J. , Howson D. , Turner G. 
Published: February 2016

AbstractThis paper describes the development of a wind turbulence criterion for the safe operation of helicopters to offshore installations. The development of the criterion was recommended following a review of the environmental effects around offshore platform helidecks.Currently, criteria exist for ambient temperature and for vertical wind component in the vicinity of helidecks, but a questionnaire-based survey of helicopter pilots revealed that the principal safety hazard and source of highest workload is turbulence around offshore installations. The new turbulence criterion will plug a long-standing gap in the guidance on offshore helideck design.The paper describes how the criterion has been developed using piloted flight simulation in a research flight simulator together with data from wind tunnel tests on offshore platforms. Initial validation has been successfully performed, and extended to include correlation with the large database of helicopter operational flight data records being collected through the UK North Sea Helicopter Operations Monitoring Programme (HOMP).The turbulence criterion will be used, together with existing criteria on vertical wind component and temperature, in the assessment of new offshore installation designs, or proposed modifications to existing designs, to determine wind conditions where turbulence is likely to be excessive for safe helicopter operations. These will be used to estimate helideck operability and thereby inform the installation topsides design process, and will provide input to the setting and maintenance of helicopter operational limitations for individual installations.The work will lead to improved safety through better prediction of safe operating envelopes and helideck operability at the design stage. In addition, development of the work is expected to enable the wind environment around offshore installations to be mapped and monitored in-service using helicopter flight data records.The new turbulence criterion has been included in updated guidance on helideck design, and offshore installation designers are now required to inform helicopter operators about wind conditions which result in violations of the turbulence criterion on their offshore installations (as is currently the case for the temperature and vertical wind component criteria).
Pressure sensitive paint measurements on a delta-wing in supersonic flow
Authors: Raju L. C. , Venkatakrishnan L. , Viswanath P. R. 
Published: February 2016

AbstractExperiments have been performed documenting the pressure field on the lee-side of a delta-wing at three incidence angles (5°, 10°, and 15°) and at Mach 1·8 using a PSP (Pressure Sensitive Paint) technique. The delta-wing model having a leading edge sweep of 60° was instrumented with 31 spanwise pressure ports at 68% of mean chord location. The Optrod-B1 binary paint was utilised and the PSP images were processed employing a resection based methodology. The comparisons of PSP results with those measured employing pressure taps show good agreement at different incidence angles.
Lean engineering: a framework for doing the right thing right
Authors: McManus H. L. , Haggerty A. , Murman E. 
Published: February 2016

AbstractLean techniques are having a major impact on aerospace manufacturing. However, the cost and value of aerospace (and many other) products is determined primarily in product development. Migrating lean to engineering processes is ongoing in the industry, and a subject of study at the MIT Lean Aerospace Initiative. This paper summarises findings to date, with references to both research literature and successful implementation examples. To implement lean engineering, a three-part approach is needed: Creating the right products, with effective lifecycle and enterprise integration, using efficient engineering processes.
Some analytical and numerical solutions for the safe turn manoeuvres of agricultural aircraft – an overview
Authors: Rasuo B. 
Published: February 2016

AbstractIn this paper, a theoretical study of the turn manoeuvre of an agricultural aircraft is presented. The manoeuvre with changeable altitude is analyzed, together with the, effect of the load factors on the turn manoeuvre characteristics during the field-treating flights. The mathematical model used describes the procedure for the correct climb and descent turn manoeuvre. For a typical agricultural aircraft, the numerical results and limitations of the climb, horizontal and descending turn manoeuvre are given. The problem of turning flight with changeable altitude is described by the system of differential equations which describe the influence of the normal and tangential load factors on velocity, the path angle in the vertical plane and the rate of turn, as a function of the bank angle during turning flight. The system of differential equations of motion was solved on a personal computer with the Runge-Kutta-Merson numerical method. Some analytical and numerical results of this calculation are presented in this paper.
An idea of distributed parameter control for scramjet engines
Authors: Daren Y. , Tao C. , Wen B. 
Published: February 2016

AbstractScramjet engines are used under extreme temperatures and with wide range of Mach numbers from 3 to 8 or higher and have shown different control properties from other airbreathing engines. New control problems involving distributed parameter control have been found concerning investigations of the control of scramjet engines whose physical states are spatially interacted and whose governing equations are partial differential equations. The work of this paper is based on the application of distributed parameter control conception to study the control problems of scramjet engines with the aim of achieving the desirable design properties and increasing control reliability. A new control idea based on shape control theory is put forward to realise the distributed parameter control of scramjet engines with the preconditions of proper space dimension and frequency-domain simplification. Simulation results and theoretic analysis for an axisymmetric, wall-injection scramjet engine show the feasibility and validity of the control idea.
The onset of compressibility effects for aerofoils in ground effect
Authors: Doig G. , Barber T. J. , Leonardi E. , Neely A. J. 
Published: February 2016

AbstractThe influence of flow compressibility on a highly-cambered inverted aerofoil in ground effect is presented, based on two-dimensional computational studies. This type of problem has relevance to open-wheel racing cars, where local regions of high-speed subsonic flow form under favourable pressure gradients, even though the maximum freestream Mach number is typically considerably less than Mach 0·3. An important consideration for CFD users in this field is addressed in this paper: the freestream Mach number at which flow compressibility significantly affects aerodynamic performance. More broadly, for aerodynamicists, the consequences of this are also considered. Comparisons between incompressible and compressible CFD simulations are used to identify important changes to the flow characteristics caused by density changes, highlighting the inappropriateness of incompressible simulations of ground effect flows for freestream Mach numbers as low as 0·15.
Method for aerodynamic unsteady forces time
calculations on an F/A-18 aircraft
Authors: Biskri D. E. , Botez R. M. 
Published: February 2016

AbstractIn this paper, a new original method based on the least
squares method is presented for the conversion of
unsteady aerodynamic forces from frequency into
Laplace domain, in which the error is written in an
analytical form as a function of the Laplace
variable, similar to the analytical form of the
aerodynamic forces calculated by use of the least
squares method. This method is applied on an F/A-18
aircraft (14 symmetric and 14 anti-symmetric modes)
for one Mach number and for a set of 14 reduced
frequencies. Two different types of results are
obtained and analysed: aerodynamic force
approximations in the Laplace domain and flutter
speeds and frequencies values. For a better
comparison of these results, different lag term
numbers are used. Results obtained by this new
method are better in terms of execution speed and
precision than the results obtained by use of the
least squares method.
Impacts of low-pressure (LP) compressor’s
deterioration of a turbofan engine upon fuel-usage
of a military aircraft
Authors: Naeem M. 
Published: February 2016

AbstractSome in-service deterioration in any mechanical device,
such as an aircraft’s gas-turbine engine, is
inevitable. However, its extent and rate depend upon
the qualities of design and manufacture, as well as
on the maintenance/repair practices followed by the
users. Deterioration of an engine normally results
in the engine seeking a different steady
operating-point relative to that for an engine
without any deterioration. The variation in engine’s
steady operating point leads to changes in the
specific fuel consumption (SFC) and/or fuel flow
(FF). Any rise in SFC and/or FF and thereby the
increased quantity of fuel required is of prime
importance in military aviation.For a military aircraft’s mission-profiles (consisting
of several flight-segments), using a bespoke
computer simulations, the consequences of
low-pressure compressor’s deterioration of an
aeroengine upon the weight of the fuel that has to
be carried and consumed are predicted. This will
help in making wiser management decisions (such as
whether to remove an aero-engine from the aircraft
for maintenance or to continue using it with some
changes in aircraft’s mission profile). Hence
improved engine utilization can be achieved, so
resulting in lower overall life-cycle costs.
Flight parameter based fatigue analysis approach for a fighter aircraft
Authors: Tikka J. A. 
Published: February 2016

AbstractThis paper describes a flight parameter based fatigue life analysis approach, which is developed for the Finnish Air Force F-18 fighters. It produces a flight specific fatigue life estimate for structural details using flight parameter data stored by each aircraft. Artificial neural networks are used to model structural response of analyzed details as a function of flight parameters. The analysis development is based on strain gauge data from 25 flights of an instrumented aircraft. The results show a satisfactory accuracy for the fatigue life estimates and prove the concept level analysis capability. The average difference between measured and modelled fatigue life is 21% for the fuselage bulkhead and 30% for the leading edge flap’s hinge area. The total differences in the Finnish Air Force average usage are extremely small, being –2% for the bulkhead and +2% for the leading edge flap.
Lateral-directional controller design using a pilot model and flight simulator experiments
Authors: Tokutake H. , Fujinaga J. , Miura Y. 
Published: February 2016

AbstractA new controller design method of lateral-directional dynamics is proposed. This method is based on the formulated pilot model, and the controller is designed so that the pilot-aeroplane system attains the desired requirements. Robust stabilities and handling qualities can be taken into account. The proposed method was applied to B747 dynamics, and flight simulator experiments were performed, and the designed controller was verified.
What price supersonic speed? an applied market research case study Part 2
Authors: Chudoba B. , Oza A. , Coleman G. , Czysz P. A. 
Published: February 2016

AbstractThe first supersonic business jet to enter the market will not face its competition from rival supersonic designs under development. Its true competitors are the then current generation of highly evolved high-subsonic business jets when compared on economic grounds. For a price tag of $1m for the new conception of very light jets, ranging up to $45m for the highest-performing ‘race-horse’-like corporate jets, this breed of aircraft is able to accommodate the needs of most executives, VIPs, officials, from corporate transportation to cargo services of civil to military origin. Understanding the state of modern business class aircraft and their market is essential in gaining base knowledge required for any supersonic business jet endeavor aiming at a prospective market. The key descriptors for this marketplace are market potential, market productivity, and market drivers, altogether being a measure for growth and consumer demand. Such common denominator is used to gain the understanding necessary to ascertain and visualise the top level implications regarding any supersonic business case. Having assembled an understanding of the key descriptors for business aviation, the study first analyses the flight operation of traditional subsonic and high-subsonic business jets. Such perceptive is then complemented with the peculiarities associated with supersonic operation, ultimately defining the supersonic solution space consisting of market viability, efficiency, and overall flight performance. Consequently, a vehicle development strategy and mission specification are suggested for the first generation of supersonic business jets (SSBJ) and supersonic cargo jets (SSCJ).
Active sensing of impact damage in composite sandwich panels by low frequency Lamb waves
Authors: Soutis C. , Diamanti K. 
Published: February 2016

AbstractThe development of a robust non-destructive system to detect and monitor the extent of damage in carbon fibre reinforced plastics (CFRP) during service life is a key problem in many practical applications, especially in the aircraft industry. The lack of such technique has severely limited the potentially extensive use of composite materials. In this study a cost and time effective inspection strategy for in-service health monitoring of composites is demonstrated using the fundamental anti-symmetric A0 Lamb mode at frequencies of 15-20kHz. In principle, this method involves analysis of the transmitted and/or reflected wave after interacting with the test-piece boundaries or discontinuities (defects). In the present work, the applicability of the technique to composite sandwich structures is explored and defects of critical size are successfully detected.
Conceptual design assessment of a suborbital tourist space access vehicle
Authors: Chudoba B. , Coleman G. , Huang X. , Czysz P. A. 
Published: February 2016

AbstractSpace transportation remains in the pioneering stages. What might this century bring if we had a ‘railroad to space’ that embodied the characteristics of the transcontinental undertaking? The X-33 and Venture Star projects were one attempt to achieve the characteristics of that transcontinental railroad. There are others, here and in other countries, but perhaps we need to begin with a smaller first step, a small, commercial reusable rocket with ballistic ascent to space altitude with a hypersonic glider return? Our challenge in space today is to develop vehicles that are in continuous use, maintained and operated on a fixed schedule despite weather or environmental hazards, which move payloads not only into space but back again. The X PRIZE was a $10 million prize awarded to Scaled Composites as the first privately financed spaceship that launched the equivalent of three persons to an altitude of at least 100 kilometers on two consecutive flights within two weeks. What about an analogous vehicle that flies two or three times a week, every week for a number of years? A major difference is that this challenge is to be accomplished without government support or government developed vehicles. The aerospace vehicle design (AVD) Laboratory team at the University of Texas at Arlington is developing a generic space access vehicle (SAV) design synthesis environment with focus on the conceptual design phase. The AVD Lab has applied elements of this toolbox to the study of a tourist aerospace vehicle under a grant from Rocketplane Limited, Inc. The development of a low-cost tourist vehicle based on the adaptation of a Learjet 25/35/45 series aircraft is the focus of this paper.
Effect of amplitude and mean angle-of-attack on the boundary layer of an oscillating aerofoil
Authors: Soltani M. R. , Bakhshalipour A. 
Published: February 2016

AbstractExtensive experiments were conducted to study the effect of various parameters on the surface pressure distribution and transition point of an aerofoil section used in a wind turbine blade. In this paper details of the variation of transition point on the aforementioned aerofoil are presented. The aerofoil spanned the wind-tunnel test section and was oscillated sinusoidally in pitch about the quarter chord. The imposed variables of the experiments were free stream velocity, amplitude of motion, mean angle-of-attack, and oscillation frequency.The spatial-temporal progressions of the leading-edge transition point and the state of the unsteady boundary-layer were measured using eight closely-spaced, hot-film sensors (HFS). The measurements show that:(i) Reduced frequency has a pronounced effect on the variations of the transition point.(ii) There exists a hysteresis loop in the dynamic transition location and its shape varies with the reduced frequency and mean angle-of-attack.
CVF ski-jump ramp profile optimisation for F-35B
Authors: Fry A. , Cook R. , Revill N. 
Published: February 2016

AbstractThis paper presents a summary of the principles and processes used to design a ski-jump ramp profile for the UK’s Future Aircraft Carrier (CVF) optimised for the Joint Strike Fighter (JSF).The paper includes an overview of the CVF and JSF programs, a history and summary of the ski-jump ramp and the principles of its use in the shipborne Short Take-Off (STO) manoeuvre.The paper discusses the importance of defining optimisation boundaries including specified objectives, aircraft configurations and environmental conditions. It then demonstrates the process of balancing the design drivers of air vehicle performance and landing gear loads to achieve an optimum profile. Comparisons are made between the proposed candidate CVF ramp profile and the current in service ski-jump design as designed for the Harrier family of aircraft.The paper briefly covers some of the important issues and factors that have been experienced when a theoretical profile is translated into a physical ramp fitted to a ship, principally the effects on aircraft operations due to build and in-service variation from the nominal profile.
Large Eddy Simulation of a complete Harrier aircraft in ground effect
Authors: Page G. J. , McGuirk J. J. 
Published: February 2016

AbstractThis paper aims to demonstrate the viability of using the large eddy simulation (LES) CFD methodology to model a representative, complete STOVL aircraft geometry at touch down. The flowfield beneath such a jet-borne vertical landing aircraft is inherently unsteady. Hence, it is argued in the present work that the LES technique is the most suitable tool to predict both the mean flow and unsteady fluctuations, and, with further development and validation testing, this approach could be a replacement, and certainly a complementary aid, to expensive rig programmes. The numerical method uses a compressible solver on a mixed element unstructured mesh. Examination of instantaneous flowfield predictions from these LES calculations indicate close similarity with many flow features identified from ground effect flow visualisations, which are well known to be difficult to model using RANS-based CFD. Whilst significant further work needs to be carried out, these calculations show that LES could be a practical tool to model, for example, Hot Gas Ingestion for the Joint Strike Fighter aircraft.
On the characteristics of a twin-jet STOVL fountain
Authors: Saddington A. J. , Knowles K. , Cabrita P. M. 
Published: February 2016

AbstractThe interaction of multiple jets with the ground is of great importance for the design and operation of short take-off, vertical landing aircraft. The fountain upwash flow, generated by the impingement of two axisymmetric, compressible, turbulent jets onto a ground plane was studied using laser-based particle image velocimetry and laser Doppler velocimetry. Measurements were made with nozzle pressure ratios of between 1·05 and 4, nozzle height-to-diameter ratios of between 2·4 and 8·4, nozzle splay angles of between ±15 degrees and a nozzle spacing-to-diameter ratio of seven. The effect of varying these parameters on the fountain velocity decay, spreading rate and momentum flux ratio are discussed. Mean fountain upwash velocity profiles were found to be self-similar for all test conditions. A distinct frequency of fountain oscillation was identified but only at a nozzle height of 4·4 diameters.
Predicting the response of low-aspect ratio, flexible aircraft
Authors: Meirovitch L. , Tuzcu I. , McGrory W. D. 
Published: February 2016

AbstractAccurate prediction of the response of low-aspect ratio, flexible aircraft requires correspondingly accurate modeling of the aircraft itself and of the aerodynamic forces, both respectable problems. Assuming that the wing can be modeled as a nonuniform plate, the discretisation process of choice is the finite element method (FEM), which demands a very large number of degrees of freedom for good accuracy. Moreover, accurate modeling of the aerodynamic forces acting on the aircraft suggests the use of computational fluid dynamics (CFD), which requires the use of an extremely large number of variables. On the other hand, feedback control design for the aircraft demands an aircraft model of relatively small order, so that the dimension of the FEM and CFD models must be reduced drastically. Based on physical considerations, reasonably accurate model reductions can be achieved, but a problem remains because the FEM and CFD grids are likely to differ from one another. It is shown in this paper how to achieve desirable model reductions for both the FEM and CFD and how to integrate the aerodynamic forces into the aircraft state equations. A numerical example demonstrates how the theory can be applied to the flight of a flexible aircraft. The analytical/computational approach developed here should permit parametric studies ultimately resulting in a reduction in the time required for aircraft design and flight testing.
Aircraft parameter estimation using a new filtering technique based upon a neural network and Gauss-Newton method
Authors: Peyada N. K. , Ghosh A. K. 
Published: February 2016

AbstractA new parameter estimation method based upon neural network is proposed. The method proposed here uses feed forward neural networks to establish a neural model that could be used to predict subsequent time histories given the suitable measured initial conditions. The proposed neural model would not represent a generic flight dynamic model. The neural model in this case develops point to point fitting of the input and the output data. Thus, it could at best be referred to as flight dynamic model in restricted sense. Gauss-Newton method is then used to obtain optimal values of the aerodynamic parameters by minimising a suitable defined error cost function. The method has been validated using longitudinal and lateral-directional flight data of various test aircraft. The results thus obtained were compared with those obtained through wind tunnel test, or those obtained using Maximum likelihood and/or Filter error methods. Unlike, most of the parameter estimation methods, the proposed method does not require a prior description of the model. It also bypasses the requirement of solving equations of motion. This feature of the proposed method may have special significance in handling flight data of an unstable aircraft.