Aeronautical Sciences Research Articles

G405 火星探査飛行機翼型の空力設計最適化(GS-4 飛翔体・円柱など,一般セッション)

Aerodynamic design optimization of an airfoil for the Mars exploration airplane has been demonstrated by using an evolutionary algorithm. The adaptive range genetic algorithm is used for efficient and robust design optimization. Two-dimensional Navier-Stokes solver is used for accurate aerodynamic performance evaluation. The present computation is parallelized on the SX-6 vector computers in Institute of Space and Aeronautical Science (ISAS) / Japan Aerospace Exploration Agency (JAXA). The optimized airfoil achieved very high aerodynamic performance. The optimum airfoil for Mars exploration airfoil has extremely thin airfoil thickness and strong camber while an optimum airfoil for typical airplane fly on Earth has substantial airfoil thickness in the front. However, a thin airfoil has disadvantages such as structural weight and fuel tank space (if an engine is used for propulsion). The present optimization indicates necessity of multiobjective design optimization for practical airfoil design for Mars exploration airplane.

Application of Low Speed Wind Tunnels in Teaching Basic Aerodynamics

Undergraduate programs that include one or more courses on basic aerodynamics, including those that are introductory to undergraduate engineering programs, can benefit from the use of low speed wind tunnels. At ERAU's Prescott Campus two low speed wind tunnels have been used to give Aeronautical Science and beginning Aerospace Engineering students hands on experiences use of these tunnels in determining the lift curve slopes for various airfoils. The objectives of these lab experiences as listed in the course syllabus are: Objectives: The student is expected to familiarize him/herself with: Fundamental wind tunnel testing techniques. The use of an open return wind tunnel to measure the static pressure acting on an airfoil. The variation in the static pressure on the surface of an airfoil at various angles of attack. The use of surface tufts to assist in airflow visualization. Objectives: Using the data taken in the experiment, the student is also required to: Plot the pressure pattern on the top and bottom of an airfoil at four different angles of attack. Calculate the lift coefficients for each of these angles of attack. .Plot the coefficient of lift against the angle of attack measurements. This paper describes a specific experiment given to undergraduate aeronautical science students. In this lab all the learning objectives can be met by using small groups of students and providing them with detailed instructions. This is one of the most popular portions of the course on basic aerodynamics.

Near-Wake Characteristics of an Oscillating NACA 4412 Airfoil

An experimental study is carried out to investigate the near-wake characteristics of an airfoil oscillating in pitch. An NACA 4412 airfoil is sinusoidally pitched about the quarter chord point between an angle of attack of -6 and +6 deg. A hot-wire anemometer is used to measure the phase-averaged velocity and turbulence intensity in the near-wake region of an oscillating NACA 4412 airfoil. The freestream velocities of the present work are 3.4, 12.4, 26.2 m/s, the corresponding Reynolds numbers are 5.3×10, 1.9×10, 4.1×10, and the reduced frequency is 0.1. Streamwise velocity and turbulence intensity profiles are presented to show the Reynolds number effects in the near-wake region behind an airfoil oscillating in pitch. All the cases in these measurements show that the velocity defects are very large at the lowest Reynolds number of Re = 5.3×10, and are small at the other Reynolds numbers of Re = 1.9 × 10 5 and 4.1×10 in the near-wake region. __________________________________________ † Assistant Professor, ‡ Associate Professor Dept. of Aeronautical Science and Flight Operation * Associate Professor Department of Aerospace Engineering Copyright  2002 The American Institute of Aeronautics, Inc. All rights reserved. A significant difference in turbulence intensity between 5.3×10 and 1.9×10 is observed. This study shows that a critical value for the Reynolds number in the nearwake of an oscillating airfoil of the present work exists in the range between 5.3×10 and 1.9×10.

Wrinkling of Composite-facing Sandwich Panels Under Biaxial Loading

The problem of face wrinkling in sandwich structures was identified as an important failure mode and first analyzed in 1940 by Gough et al. [1], who used a Winkler-type elastic foundation to model the core. This work was followed by experiments and further analysis by many others. Until 1966 all of the research was devoted to uniaxial compression loading. However, in many applications, such as naval and aircraft structures, panels are subjected to biaxial loading. Such loadings were first analyzed by Plantema in 1966 [2] for the case of sandwich constructed of isotropic materials. Sullins et al. [3] suggested an interaction equation that can be used as a criterion of wrinkling under compression in the principal directions. This equation is formulated in terms of the ratios of the principal compressive stresses to the corresponding wrinkling stresses. More recently Fagerberg [4, 5] and Vonach and Rammerstorfer [6] considered the case of sandwich with orthotropic facings. The present work attacks the subject problem using three different models for the core. One model uses a simple Winkler elastic foundation approach. The second model, following Hoff and Mautner [Hoff, N.J. and Mautner, S.E. (1945). The Buckling of Sandwich-Type Panels, Journal of the Aeronautical Sciences, 12: 285–297.], uses a linear model for the decay in deformation from the core-facing interface, while the third model, following Plantema [Plantema, F.J. (1966). Sandwich Construction, John Wiley & Sons, Inc., New York.], uses an exponential decay.

Concorde and the Future of Supersonic Transport

Commercial high-speed flight at supersonic speeds poses major technological challenges that were resolved during the 1960s and early 1970s and that led to a unique vehicle in the history of air transportation. The demonstration of sustained supersonic flight has been made on a regular basis by operating the Concorde over a period of more than a quarter of a century. It has also served to show the limitations of this remarkable aircraft. Commercial operation of Concorde ceased in 2003. It is timely to look back at this adventure and review how this aircraft evolved from a project to a vehicle, identify some of the lessons learned from this experience, and possibly dwell on these lessons for future development of a new supersonic aircraft program. From this viewpoint, it has become clear that no new supersonic transport could be designed without first breaking many fundamental and technical barriers. A new project will benefit from the modern tools devised by aeronautical science and technology during the last period, but advances will have to be made to resolve many difficult challenges. The main areas of progress are related to the environmental impact of the vehicle, to its global performance, and to operational considerations. Meeting the challenges will require fundamental progress in aerodynamic optimization for sonic boom and drag reduction, combustion management for emission reduction, engine design to comply with noise regulations, and propulsion integration to improve performance. The environmental impact of a fleet of supersonic airliners will have to be carefully evaluated and compared to that of an all subsonic air transportation system.

Crack blunting and the strength of soft elastic solids

When a material is so soft that the cohesive strength (or adhesive strength, in the case of interfacial fracture) exceeds the elastic modulus of the material, we show that a crack will blunt instead of propagating. Large–deformation finite–element model (FEM) simulations of crack initiation, in which the debonding processes are quantified using a cohesive zone model, are used to support this hypothesis. An approximate analytic solution, which agrees well with the FEM simulation, gives additional insight into the blunting process. The consequence of this result on the strength of soft, rubbery materials is the main topic of this paper. We propose two mechanisms by which crack growth can occur in such blunted regions. We have also performed experiments on two different elastomers to demonstrate elastic blunting. In one system, we present some details on a void growth mechanism for ultimate failure, post–blunting. Finally, we demonstrate how crack blunting can shed light on some long–standing problems in the area of adhesion and fracture of elastomers.

Message to the Japan Society for Aeronautical and Space Science

Message to the Japan Society for Aeronautical and Space Science

Desirable Faculty Qualifications as Assessed by Students in the Aeronautical Science Program at Embry-Riddle Aeronautical University

Over 89% of the sophomore aerodynamics students (182 out of 207) at Embry-Riddle Aeronautical University were surveyed during Spring Term 2003 to explore student preferences relative to instructor qualifications in the Aeronautical Science Program. The study was initiated because of the great difficulty that particular department, as in many aviation-focused universities, has had recruiting PhD credentialed faculty with significant professional or military flight experience. To perhaps aid in the hiring process, a tough question was asked: Do students prefer PhD level faculty with limited flight experience or Masters level faculty with significant professional or military flight experience? Results indicated that although students would like to see both PhD credentials and significant profession or military flight experience, when given a choice they prefer faculty with significant professional or military flight experience, even if the faculty member has only obtained a Master's degree. It is speculated that the reason might relate to the evidence that shows, "... students engaged in pursuing collegiate aviation programs are 'different' from traditional college students. Aviation students are not searching for a career; they have found one and are taking steps to realize their dreams. They approach learning as an adult." (Brady, Stolzer, Muller and Schaum, 2001).

On aerodynamic modelling of an insect–like flapping wing in hover for micro air vehicles

This theoretical paper discusses recent advances in the fluid dynamics of insect and micro air vehicle (MAV) flight and considers theoretical analyses necessary for their future development. The main purpose is to propose a new conceptual framework and, within this framework, two analytic approaches to aerodynamic modelling of an insect-like flapping wing in hover in the context of MAVs. The motion involved is periodic and is composed of two half-cycles (downstroke and upstroke) which, in hover, are mirror images of each other. The downstroke begins with the wing in the uppermost and rearmost position and then sweeps forward while pitching up and plunging down. At the end of the half-cycle, the wing flips, so that the leading edge points backwards and the wing's lower surface becomes its upper side. The upstroke then follows by mirroring the downstroke kinematics and executing them in the opposite direction. Phenomenologically, the interpretation of the flow dynamics involved, and adopted here, is based on recent experimental evidence obtained by biologists from insect flight and related mechanical models. It is assumed that the flow is incompressible, has low Reynolds number and is laminar, and that two factors dominate: (i) forces generated by the bound leading-edge vortex, which models flow separation; and (ii) forces due to the attached part of the flow generated by the periodic pitching, plunging and sweeping. The first of these resembles the analogous phenomenon observed on sharp-edged delta wings and is treated as such. The second contribution is similar to the unsteady aerodynamics of attached flow on helicopter rotor blades and is interpreted accordingly. Theoretically, the fluid dynamic description is based on: (i) the superposition of the unsteady contributions of wing pitching, plunging and sweeping; and (ii) adding corrections due to the bound leading-edge vortex and wake distortion. Viscosity is accounted for indirectly by imposing the Kutta condition on the trailing edge and including the influence of the vortical structure on the leading edge. Mathematically, two analytic approaches are proposed. The first derives all the quantities of interest from the notion of circulation and leads to tractable integral equations. This is an application of the von Kármán-Sears unsteady wing theory and its nonlinear extensions due to McCune and Tavares; the latter can account for the bound leading-edge vortex and wake distortion. The second approach uses the velocity potential as the central concept and leads to relatively simple ordinary differential equations. It is a combination of two techniques: (i) unsteady aerodynamic modelling of attached flow on helicopter rotor blades; and (ii) Polhamus's leading-edge suction analogy. The first of these involves both frequency-domain (Theodorsen style) and time-domain (indicial) methods, including the effects of wing sweeping and returning wake. The second is a nonlinear correction accounting for the bound leading-edge vortex. Connections of the proposed framework with control engineering and aeroelasticity are pointed out.

An energy formulation for high-frequency radiation into an unbounded acoustic medium

A new energy formulation for computing high-frequency radiation from structures into an unbounded acoustic medium is presented. The outer surface of the radiating structure is divided into elements. Surface intensity values on each element comprise the boundary conditions. Similar to the panel method [J. L. Hess and A. M. O. Smith, Calculation of Potential Flow About Arbitrary Bodies, Progress in Aeronautical Sciences Vol. 8, edited by D. Kuchemann (Pergamon, New York, 1967)] a distribution of fictitious energy sources and sinks is considered over the surface of the model. Appropriate strengths are computed for the sources and the sinks in order to satisfy the intensity boundary conditions. Once the distribution of the surface sources/sinks has been completed, the acoustic energy density and the acoustic intensity can be evaluated at any point on the surface of the radiating object, or at any field point within the acoustic medium. The new development does not require one to define damping properties for the infinite fluid and no assumptions are made about representing the radiated acoustic field as reverberant. The new developments are validated through comparisons of numerical results to analytical solutions. [Research supported by ONR, Contract No. N00014-00-I-0382.]

Energy conservation during a tanker collision

The energy dissipation on the bow structure is calculated during a “head-on” collision with a rigid body, using finite element analysis. Gerard's method ( Gerard, G., 1958. The crippling strength of compression elements. Journal of the Aeronautical Sciences), an empirical approach, is compared with the results produced by ABAQUS in terms of velocity, energy and penetrating distance. The energy conservation theorem is applied and the contribution of all individual structural members in terms of elastic and plastic energy is calculated. The strain distribution is shown for those members responsible for the water tightness and structural integrity of the structure. The global bending of the upper part of the bow is shown as well as the effect of the total ship mass inertia, phenomena which have not been incorporated into Gerard's approach ( Gerard, 1958). The final time of rest predicted from both methods is compatible and this validates the reliability of the numerical approach.

The royal aeronautical society

Founded in 1866 for ‘the general advancement of aeronautical art, science and engineering’, the Royal Aeronautical Society is the oldest aeronautical society in the world. Its original purpose was to promote heavier than air flight - an achievement realised some 37 years after the its formation. Since then, the Society has been a focus of aerospace activity and has evolved as a global focal point for the aerospace community with 18000 members in over 100 countries.

Message to the Japan Society for Aeronautical and Space Science

Message to the Japan Society for Aeronautical and Space Science

Extract from A Wrack Behind

In 1943, with the world still at war, a great discussion on the future of aeronautical education was held by the Royal Aeronautical Society. Not only would the war years, however many were still to come, demand more well-qualified aeronautical engineers, but the longed for peace years, with engineers turning swords into ploughshares, would want more. The discussion was in two parts. One took place on 25 June and the other on 23 July. Many of the leading figures in British aeronautics took part and in the chair on both occasions was Dr Roxbee Cox, a vice-president of the society. The discussion culminated in a resolution based on a proposal by Marcus Langley. That resolution and the discussion which led to it resulted in the recommendation by the Aeronautical Research Committee that a post-graduate college of aeronautical science should be established. This was followed by governmental action. Sir Stafford Cripps, then the minister responsible for aircraft production, set up a committee presided over by Sir Roy Fedden to make specific proposals, and the committee recommended in its 1944 report that such a college should be a new and independent establishment. In 1945 the government created the College of Aeronautics board of governors under the chairmanship of Air Chief Marshal Sir Edgar Ludlow-Hewitt to bring the college into existence and govern it. The first meeting of this board took place on 28 June 1945 and there were present:Sir Edgar Ludlow Hewitt, Dr W. Abbot, Mr Hugh Burroughs, Sir Roy Fedden, Mr J. Ferguson, Sir Harold Hartley, Sir William Hil-dred, Sir Melvill Jones, Dr E.B. Moullin, Mr J.D. North, Sir Frederick Handley Page, Mr E.F. Relf, Dr H. Roxbee Cox, Air Marshal Sir Ralph Sovley, Rear Admiral S.H. Troubridge and Mr W.E.P. Ward. Sir William Stanier, who had been appointed, was not present.

Address at St Margaret’s, Westminster, The Lord Kings Norton

We, his family and friends, are gathered here today in the heart of London to remember and to give thanks for the life and work of one of the truly great men of our time — the Lord Kings Norton of Wotton Underwood, ‘Roxbee’ to the legion of his friends and colleagues.Through the many years of his active life, there were hardly any avenues of the aeronautical sciences to which he had not made (and enjoyed the making of) inspired contributions.He was, indeed, “A Happy Warrior”.If the question was to be asked — “What, among all Lord Kings Norton’s many achievements, were those most to be acclaimed?”, the answer, among such a galaxy, could, perhaps, be four.

Pushing the envelope: the American aircraft industry

Pushing the Envelope, a survey history of the American aircraft (now aerospace) manufacturing industry, is the most comprehensive history on the subject ever completed. Though it covers the development of the industry from the beginnings of flight to the present, it provides far more than a simple chronology by analyzing key economic, military, technical, and international influences on the industry and showing how the industry has been instrumental in American military and technological leadership from its modest beginnings.Using original sources whenever available, Pushing the Envelope focuses on the business of aircraft. It is neither an aeronautical nor a production history of the industry, although both aspects are addressed. Instead, Donald M. Pattillo features the development and production of aircraft in different periods in the context of aeronautical progress. Pushing the Envelope also establishes that the central fact of the industry's existence, its dependence on military contracts, has been simultaneously its greatest strength and greatest vulnerability. Even during periods of military expansion, Pattillo illustrates, it has always been an unstable and insecure enterprise.Carefully researched, Pushing the Envelope also assesses the environmental impacts on the industry, including those pressures that have often led it into ethical dispute. Unlike any other technological industry, the unique qualities of the aircraft industry are truly paradoxical--although it provides vital technical and production capability to the nation, demand for its capabilities may be influenced by external developments that it cannot foresee or influence.Pushing the Envelope transcends narrow disciplines, commingling aeronautical science and technology, business management, international business, the history of science and technology, national security studies, and international relations. Written in nontechnical language, it can easily be understood by a diverse audience, including industry and military professionals as well as the general public interested in aviation and technology. With Pushing the Envelope, Pattillo fills a most conspicuous gap in the literature of both aviation and industrial history.Donald M. Pattillo is an educational consultant in Acworth, Georgia.

The essential work of fracture and JR curves for the double cantilever beam specimen: an examination of elastoplastic crack propagation

The propagation of a crack in a double-cantilever beam (DCB) geometry where there is extensive remote plastic flow both preceding and accompanying fracture is analysed. Experiments show that there ...

Decentralized Control of Expandingly Constructed Large Space Structures

References 1Nicolaides, J. D., “On the Free FlightMotion of Missiles Having Slight ConŽ gurational Asymmetries,” U.S. Army Ballistics Research Lab., Rept. R858, Aberdeen Proving Ground,MD, June 1953. 2Nicolaides, J. D., “Two Nonlinear Problems in the Flight Mechanics of Modern Ballistic Missiles,” Inst. of Aeronautical Sciences, Rept. 59-11, Univ. of Toronto, ON, Canada, Jan. 1959. 3Murphy, C. H., “Responses of an Asymmetric Missile to Spin Varying Through Resonance,” AIAA Journal, Vol. 9, No. 11, 1971, pp. 2197–2201. 4Nayfeh, A. H., and Saric, W. S., “An Analysis of Asymmetric Rolling Bodies with Nonlinear Aerodynamics,” AIAA Journal, Vol. 10, No. 8, 1972, pp. 1004–1011. 5Murphy, C. H., “Some Special Cases of Spin-Yaw Lock In,” Journal of Guidance, Control, and Dynamics, Vol. 12, No. 6, 1989, pp. 771–776. 6Ananthkrishnan, N., and Raisinghani, S. C., “Steady and Quasisteady Resonant Lock-In of Finned Projectiles,” Journal of Spacecraft and Rockets, Vol. 29, No. 5, 1992, pp. 692–696. 7Ashley, H., Engineering Analysis of Flight Vehicles, Addison–Wesley, Reading, MA, 1974, pp. 173–202. 8Gollub, J. P., and Swinney, H. L., “Onset of Turbulence in a Rotating Fluid,” Physical Review Letters, Vol. 35, Dec. 1975, pp. 927–930.

Would ACES Academy Benefit Your University?

In 1989 the Federal Aviation Administration (FAA) entered into a collaborative effort with Embry-Riddle Aeronautical University to design a model Aviation Career Education (ACE) Academy seminar. This collaboration was initially made exclusively with Embry-Riddle with the intent to replicate the program at other institutions after the model was established. The objective of the seminar was to introduce high school juniors and seniors to various aviation careers, allowing them to plan their final semesters in high school and set their higher-education goals. Additional goals of the program included: 1. Guiding high school students in exploring the role of aviation in history. 2. Discussing the airplane as a vehicle and identifying its parts and the principles by which it flies. 3. Taking participants on a flight to give them firsthand experience. 4. Helping students explore careers in aviation and aerospace. 5. Explaining the role of government in aviation and the overall socio-economic benefits of aviation. The FAA contacted Patricia Ryan, director of the Teacher Resource Center at Embry-Riddle, who developed the program with the assistance of Dave Esser, an associate professor in Embry-Riddle's Aeronautical Science Department. The FAA has since offered the program developed by Ryan and Esser at various locations around the nation. In 1994, Ryan and Esser decided the project could be better tailored to meet individual needs if each student was allowed to select a particular career field to explore. The enhanced program was renamed Aviation Career Education Specialization (ACES) Academy.

Satellites, scientists track storm from Sun to surface

On January 6, the Sun spat a coronal mass ejection (CME) into the solar wind and toward Earth; by January 10, a cloud of charged particles buffeted the face of the planet. It was, by several accounts, a run‐of‐the‐mill space weather event. But the scientific work surrounding the storm was anything but run‐of‐the‐mill.For the first time, space physicists observed and recorded a space weather event from start to finish, from solar surface to earthly impact. Researchers are calling it the first true success story of the four‐year‐old International Solar Terrestrial Physics program (ISTP), which includes NASA's WIND and POLAR spacecraft; the joint Solar and Heliospheric Observatory (SOHO) mission of NASA and the European Space Agency; the joint Geotail mission of NASA and Japan's Institute of Space and Aeronautical Science; and Russia's Interball satellites.