DOCSLIB.ORG

Historical Development of Aircraft Flutter

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Historical Development of Aircraft Flutter VOL. 18, NO. 11 J . AIRCRAFT NOVEMBER 1981 History o f Ke y Technologies AIAA 81-0491R Historical Development of Aircraft Flutter I . E Garrick an d Wilmer H . Reed II I NASA Langley Research Center, Hampton, Va. Introduction Work in flutter has been (and is being) pursued in many EROELASTICITY, and in particular flutter, has in- countries. As in nearly all fields, new ideas and developments A fluenced th e evolution o f aircraft since th e earliest days in flutter have occurred similarly and almost simultaneously of flight. This paper presents a glimpse of problems arising in in diverse places in the world, so that exact assignment of these areas an d ho w they were attacked b y aviation's pioneers priorities i s often i n doubt. Moreover, a definitive historical an d their successors u p t o about th e mid-1950s. Th e emphasis account would require several volumes; yet we hope to survey is on tracing some conceptual developments relating to the some o f th e main developments i n a proper historical light, understanding an d prevention o f flutter including some an d i n a wa y that th e lessons learned ma y b e currently useful. lessons learned along th e way. It is recognized that detailed documentation of flutter Because it must be light, an airplane necessarily deforms troubles has nearly always been hampered by proprietary appreciably under load. Such deformations change the conditions an d b y a reluctance o f manufacturers t o expose distribution o f th e aerodynamic load, which i n turn changes such problems. th e deformations; th e interacting feedback process ma y lead From our present perspective, flutter is included in the to flutter, a self-excited oscillation, often destructive, wherein broader term aeroelasticity, the study of the static and energy is absorbed from the airstream. Flutter is a complex dynamic response o f a n elastic airplane. Since flutter involves phenomenon that must i n general b e completely eliminated b y the problems of interaction of aerodynamics and structural design o r prevented from occurring within th e flight envelope. deformation, including inertial effects, at subcritical as well The initiation of flutter depends directly on the stiffness, and a s t critical speeds, i t really involves al l aspects o f only indirectly o n th e strength o f a n airplane, analogous t o aeroelasticity. I n a broad sense, aeroelasticity i s a t work i n depending on the slope of the lift curve rather than on the natural phenomena such as in the motion of insects, fish, and maximum lift. This implies that the airplane must be treated birds (biofluid-dynamics). I n man's handiwork, aeroelastic no t a s rigid body bu t a s n elastic structure. Despite th e fact problems o f windmills were solved empirically four centuries that the subject is an old one, this requires for a modern ago in Holland with the moving of the front spars of the airplane a large effort in many areas, including ground blades from about th e midchord t o th e quarter-chord position vibration testing, use of dynamically scaled wind-tunnel (see th e article b y Ja n Drees i n list o f Survey Papers). W e no w models, theoretical analysis, an d flight flutter testing. Th e recognize that some 19th century bridges were torsionally aim of this paper is to give a short history of aircraft flutter, weak an d collapsed from aeroelastic effects, a s di d th e with emphasis o n th e conceptual developments, from th e Tacoma Narrows Bridge i n spectacular fashion i n 1940. Other early days o f flight t o about th e mid-1950s. aeroelastic wind-structure interaction pervades civil After a long career a s research scientist an d manager, I . E Garrick retired from NACA/NASA i n 1972. H e remains active a s Distinguished Research Associate o f Langley. H e i s th author o f numerous publications in areas of aerodynamics, aeroelasticity, and aeromechanics, has served on many advisory councils, an d ha s lectured extensively. Mr . Garrick served fo r a year a s th e second Hunsaker Professor o f Aeronautical Engineering a t MIT. Hi s 1976 AIAA vo n Karman Lecture dealt with th e topic: "Aeroelasticity—Frontiers an d Beyond." Among hi s awards ar e th NASA Exceptional Service Award, the Langley Scientific Achievement Award, and the AIAA Sylvanus A. Reed Award. He is a Fellow of the AIAA. Wilmer H . Reed II I from 1972 t o 1980 wa s Head o f th e Aeroelasticity Branch which operates th e Langley Transonic Dynamics Tunnel, a national facility dedicated exclusively t o research an d development i n th e field o f aeroelasticity. Notably, this facility i s used b y th e United States i n develop- ment of practically all its military aircraft, commercial transports, and launch vehicles. At present, Mr. Reed i s Chief Scientist, Loads an d Aeroe'.asticity Division, NASA Langley Research Center. H e joined NACA/NASA in 1948 and holds Bachelor and Master degrees in Aeronautical Engineering from Auburn University an d th e University o f Virginia. Hi s professional experience includes research i n aeroelasticity, wind loads o n structures, damping devices, an d wind tunnel testing techniques. H e received th e NASA Exceptional Service Medal in 1979, holds several U.S. Patents, is a member of Tau Beta Pi, and an Associate Fellow of the AIAA. Presented as Paper 81-0491 at the AIAA/ASME/ASCE/AHS 22nd Structures, Structural Dynamics and Materials Conference, Atlanta, Ga., April 6-8, 1981; submitted April 14 , 1981; revision received July 8 , 1981. This paper i s declared a work o f th e U.S. Government an d therefore i s n the public domain. EDITOR'S NOTE: This manuscript wa s invited a s History o f Ke y Technologies paper a s part o f AIAA's 50th Anniversary celebration. I t i s no meant to be a comprehensive survey of the field. It represents solely the authors' own reconstruction of events at the time and is based upon their own experiences. 897 898 I. E. GARRICK AND W.H. REED III J. AIRCRAFT engineering. The elastic response of an airplane to rough air (gusts o r turbulence) i s a n important aeroelastic problem requiring separate study an d documentation. A s th e phenomena an d concepts have unfolded, aeroelasticity, and flutter in particular, have been the subjects of many survey papers throughout the years. These papers often furnish valuable assessments of the state-of-the-art, give interesting bits of the history, and also furnish numerous useful references. A s i t feasible t o refer t o only a small fraction o f these references individually, w e have included a list of such survey papers separate from quoted references. In particular, we may refer the reader to the outstanding survey papers o f A . R Collar, which emphasize th e British developments, th e most recent o f which, "The First Fifty Years o f Aeroelasticity," came t o ou r attention during th e writing o f this paper. I t wa s Collar's "Aeroelastic Triangle" (1947) that showed graphically that flutter embraced all aspects of aeroelasticity. Fig. 1 Langley's aerodrome, which plunged into th e Potomac River The Early Years, 1903-1919 in 1903. Th e Wright Brothers I n their historic flight, Orville an d Wilbur Wright made Brewer3 on the collapse of monoplane wings. Brewer notes in beneficial us e o f aeroelastic effects fo r roll control o f their his one-page article i n Flight Magazine that a rash o f biplane by the use of wing warping in place of ailerons. They monoplane wings with stays had had "accidents in which the also were aware o f th e adverse aeroelastic effect o f th e loss o f wings break downward" and he remarks that "the greater the thrust o f a propeller, du e t o twisting o f th e blades, b y their span th e more readily will th e wing tips b e twisted"; an d that experiments o n th e performance o f thin propellers having the movement of the center of pressure with speed could put it broad blades. They found that th e propeller ti p under high behind th e attachment point o f th e rear stay, resulting i n thrust loads twisted to partially unload itself. We quote from 1 sudden wing flip. The Papers of Wilbur and Orville Wright : Professor Collar (see Survey Papers, 1958, 1978) ha s stated Orville Wright, i n later life, explained th e that part of the speculation about Langley's airplane disaster nature and function of the "little jokers" to Fred is based on the circumstances that some years after Langley's C . Kelley, wh o states i n hi s book, Th e Wright death the original Langley machine was removed from the Brothers, "After th e Wrights ha d made th e Smithsonian National Museum, modified, an d flown suc- blades o f their propellers much wider an d thinner cessfully a t Hammondsport, N.Y. These modifications, than th e original ones, they discovered that th e which involved substantial changes i n th e wing structure an d performance o f th e propellers i n flight di d no t trussing, s o strengthened an d stiffened th e original structure agree closely with their calculations, as in the a s t o significantly reduce th e probability o f aeroelastic failure.
Load more

Recommended publications
  • Introduction to Aircraft Aeroelasticity and Loads
    JWBK209-FM-I JWBK209-Wright November 14, 2007 2:58 Char Count= 0 Introduction to Aircraft Aeroelasticity and Loads Jan R. Wright University of Manchester and J2W Consulting Ltd, UK Jonathan E. Cooper University of Liverpool, UK iii JWBK209-FM-I JWBK209-Wright November 14, 2007 2:58 Char Count= 0 Introduction to Aircraft Aeroelasticity and Loads i JWBK209-FM-I JWBK209-Wright November 14, 2007 2:58 Char Count= 0 ii JWBK209-FM-I JWBK209-Wright November 14, 2007 2:58 Char Count= 0 Introduction to Aircraft Aeroelasticity and Loads Jan R. Wright University of Manchester and J2W Consulting Ltd, UK Jonathan E. Cooper University of Liverpool, UK iii JWBK209-FM-I JWBK209-Wright November 14, 2007 2:58 Char Count= 0 Copyright C 2007 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) 1243 779777 Email (for orders and customer service enquiries): [email protected] Visit our Home Page on www.wileyeurope.com or www.wiley.com All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. Requests to the Publisher should be addressed to the Permissions Department, John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England, or emailed to [email protected], or faxed to (+44) 1243 770620.
    [Show full text]
  • CHAPTER TWO - Static Aeroelasticity – Unswept Wing Structural Loads and Performance 21 2.1 Background
    Static aeroelasticity – structural loads and performance CHAPTER TWO - Static Aeroelasticity – Unswept wing structural loads and performance 21 2.1 Background ........................................................................................................................... 21 2.1.2 Scope and purpose ....................................................................................................................... 21 2.1.2 The structures enterprise and its relation to aeroelasticity ............................................................ 22 2.1.3 The evolution of aircraft wing structures-form follows function ................................................ 24 2.2 Analytical modeling............................................................................................................... 30 2.2.1 The typical section, the flying door and Rayleigh-Ritz idealizations ................................................ 31 2.2.2 – Functional diagrams and operators – modeling the aeroelastic feedback process ....................... 33 2.3 Matrix structural analysis – stiffness matrices and strain energy .......................................... 34 2.4 An example - Construction of a structural stiffness matrix – the shear center concept ........ 38 2.5 Subsonic aerodynamics - fundamentals ................................................................................ 40 2.5.1 Reference points – the center of pressure..................................................................................... 44 2.5.2 A different
    [Show full text]
  • Introduction to Aeroelasticity.Pdf
    Aeroelasticity Dr. Ugur GUVEN Aerospace Engineer (P.hD) Nuclear Science and Technology Engineer (M.Sc) What is Aeroelasticity • Aeroelasticity is broadly defined as the interaction between the aerodynamic forces and the structural forces causing a deformation in the structure of the aerospace craft as well as in its control mechanism or in its propulsion systems. Importance of Aeroelasticity • Aeroelasticity has become a very important force especially after the 1950’s. • The interaction between aerodynamic loads and structural deformations have gained great importance in view of factors related to the design of aircraft as well as missiles. • Aeroelasticity plays at least some part on fuel sloshing as well as on the reentry of spacecraft in astronautics. Trends in Technology • Due to the advancements in technology, it has become quite common to see the slenderness ratio (ratio of length of wing span to thickness at the root) increase. • The wing span area as well as the length of aircrafts have increased causing aircraft to become much more susceptible to interaction between structural loads and aerodynamic loads Slenderness Ratio Effect of Aerodynamic Loads • The forces of lift and drag as well as torsion moment will have some sort of effect on the structural integrity of the spacecraft. • In many cases, some parts of aircraft or spacecraft may bend or ripple slightly due to these loads. • The frequency of these loads and effects can also cause the aircraft’s structure to suffer from metal fatigue in the long run. Scope of Aeroelasticity Vibration • One of the ways in which aerodynamic and structural forces collide with each other is through vibration.
    [Show full text]
  • Comparison of Theodorsen's Unsteady Aerodynamic Forces with Doublet Lattice Generalized Aerodynamic Forces 5B
    NASA/TM–2017-219667 Comparison of Theodorsen’s Unsteady Aerodynamic Forces with Doublet Lattice Generalized Aerodynamic Forces Boyd Perry, III Langley Research Center, Hampton, Virginia September 2017 NASA STI Program . in Profile Since its founding, NASA has been dedicated to the x CONFERENCE PUBLICATION. advancement of aeronautics and space science. The Collected papers from scientific and technical NASA scientific and technical information (STI) conferences, symposia, seminars, or other program plays a key part in helping NASA maintain meetings sponsored or co-sponsored by NASA. this important role. x SPECIAL PUBLICATION. Scientific, The NASA STI program operates under the auspices technical, or historical information from NASA of the Agency Chief Information Officer. It collects, programs, projects, and missions, often organizes, provides for archiving, and disseminates concerned with subjects having substantial NASA’s STI. The NASA STI program provides access public interest. to the NTRS Registered and its public interface, the NASA Technical Reports Server, thus providing one x TECHNICAL TRANSLATION. of the largest collections of aeronautical and space English-language translations of foreign science STI in the world. Results are published in both scientific and technical material pertinent to non-NASA channels and by NASA in the NASA STI NASA’s mission. Report Series, which includes the following report types: Specialized services also include organizing and publishing research results, distributing x TECHNICAL PUBLICATION. Reports of specialized research announcements and feeds, completed research or a major significant phase of providing information desk and personal search research that present the results of NASA support, and enabling data exchange services. Programs and include extensive data or theoretical analysis.
    [Show full text]
  • AAE556-Aeroelasticity
    AIRCRAFT AEROELASTIC DESIGN AND ANALYSIS An introduction to fundamental concepts of static and dynamic aeroelasticity - with simple idealized models and mathematics to describe the essential features of aeroelastic problems. These notes are intended for the use of Purdue University students enrolled in AAE556. They are not for sale or intended for distribution to others, but may be used for educational purposes, with prior permission of the author. Terry A. Weisshaar Purdue University © 1995 (Second edition -2009) Introduction - page 1 Preface to Second Edition – The purpose and scope These notes are the result of three decades of experiences teaching a course in aeroelasticity to seniors and first or second year graduate students. During this time I have presented lectures and developed homework problems with the objective of introducing students to the complexities of a field in which several major disciplines intersect to produce major problems for high speed flight. These problems affect structural and flight stability problems, re-distribution of external aerodynamic loads and a host of other problems described in the notes. This three decade effort has been challenging, but more than anything, it has been fun. My students have had fun and have been contributors to this teaching effort. Some of them have even gone on to surpass my skills in this area and to be recognized practitioners in this area. First of all, let me emphasize what these notes are not. They are not notes on advanced methods of analysis. They are not a “how to” book describing advanced methods of analysis required to analyze complex configurations. If your job is to compute the flutter speed of a Boeing 787, you will have to learn that skill elsewhere.
    [Show full text]
  • A Historical Overview of Flight Flutter Testing
    tV - "J -_ r -.,..3 NASA Technical Memorandum 4720 /_ _<--> A Historical Overview of Flight Flutter Testing Michael W. Kehoe October 1995 (NASA-TN-4?20) A HISTORICAL N96-14084 OVEnVIEW OF FLIGHT FLUTTER TESTING (NASA. Oryden Flight Research Center) ZO Unclas H1/05 0075823 NASA Technical Memorandum 4720 A Historical Overview of Flight Flutter Testing Michael W. Kehoe Dryden Flight Research Center Edwards, California National Aeronautics and Space Administration Office of Management Scientific and Technical Information Program 1995 SUMMARY m i This paper reviews the test techniques developed over the last several decades for flight flutter testing of aircraft. Structural excitation systems, instrumentation systems, Maximum digital data preprocessing, and parameter identification response algorithms (for frequency and damping estimates from the amplltude response data) are described. Practical experiences and example test programs illustrate the combined, integrated effectiveness of the various approaches used. Finally, com- i ments regarding the direction of future developments and Ii needs are presented. 0 Vflutte r Airspeed _c_7_ INTRODUCTION Figure 1. Von Schlippe's flight flutter test method. Aeroelastic flutter involves the unfavorable interaction of aerodynamic, elastic, and inertia forces on structures to and response data analysis. Flutter testing, however, is still produce an unstable oscillation that often results in struc- a hazardous test for several reasons. First, one still must fly tural failure. High-speed aircraft are most susceptible to close to actual flutter speeds before imminent instabilities flutter although flutter has occurred at speeds of 55 mph on can be detected. Second, subcritical damping trends can- home-built aircraft. In fact, no speed regime is truly not be accurately extrapolated to predict stability at higher immune from flutter.
    [Show full text]
  • Aeroelasticity
    1 Matthew Moraguez Aeroelasticity What is Aeroelasticity? An airplane’s wing generates an upward AEROELASTICITY, NOUN force, known as lift, when it passes through air. Although lift is needed for a plane to fly, A term used in the field of aerospace its effect on the structure of the plane can be engineering to describe the interaction harmful. Aeroelasticity refers to the between a structure and a moving fluid [1]. deformation of an airplane’s wing in response to aerodynamic forces, such as lift. [1] Static vs. Dynamic Aeroelasticity Aeroelastic effects are classified as either static or dynamic. While static effects reach an equilibrium, dynamic effects are defined by oscillations [2]. Static Aeroelasticity: Aeroelasticity applies to Divergence refers to a process in which the lift a wing produces causes the wing itself to twist. This twisting any situation in which a leads to greater lift, which causes more twisting. The fluid (gas or liquid) flows process continues until equilibrium is reached [1]. In around a structure [3]. order to prevent divergence, a wing must be stiff enough to prevent twisting. If the wing is too flexible or the force of lift is too strong, divergence will occur [2]. DID YOU KNOW? Aileron reversal occurs when wing twisting causes the plane’s response to the pilot’s commands to be Aeroelasticity affects airplane reversed from the expected. In other words, when a stability, bridge design, and even blood flow through the body! [3] pilot tries to turn left, the plane will turn right [2]. Dynamic Aeroelasticity: Above a critical wind speed, a wing experiences flutter instability, which causes the wing to oscillate.
    [Show full text]
  • FLUID DYNAMICS, Volume IV
    http://dx.doi.org/10.1090/psapm/004 PROCEEDINGS OF SYMPOSIA IN APPLIED MATHEMATICS VOLUME IV FLUID DYNAMICS McGRAW-HILL BOOK COMPANY, INC. NEW YORK TORONTO LONDON 1953 FOR THE AMERICAN MATHEMATICAL SOCIETY 80 WATERMAN STREET, PROVIDENCE, RHODE ISLAND PROCEEDINGS OF THE FOURTH SYMPOSIUM IN APPLIED MATHEMATICS OF THE AMERICAN MATHEMATICAL SOCIETY Held at the University of Maryland June 22-23, 1951 COSPONSORED BY THE U.S. NAVAL ORDNANCE LABORATORY M. H. Martin EDITOR EDITORIAL COMMITTEE R. V. Churchill Eric Reissner A. H. Taub Copyright, 1953, by the McGraw-Hill Book Company, Inc. Printed in the United States of America. All rights reserved. This book, or parts thereof, may not be reproduced in any form without permission of the publishers. Library of Congress Catalog Card Number: 52-10326 CONTENTS EDITOR'S PREFACE v Some Aspects of the Statistical Theory of Turbulence 1 BY S. CHANDRASEKHAR A Critical Discussion of Similarity Concepts in Isotropic Turbulence 19 BY C. C. LIN The Nonexistence of Transonic Potential Flow 29 BY ADOLF BUSEMANN On Waves of Finite Amplitude in Ducts (Abstract) 41 BY R. E. MEYER On the Problem of Separation of Supersonic Flow from Curved Profiles .... 47 BY T. Y. THOMAS On the Construction of High-speed Flows 55 BY G. F. CARRIER AND K. T. YEN An Example of Transonic Flow for the Tricomi Gas 61 BY M. H. MARTIN AND W. R. THICKSTUN On Gravity Waves 75 BY A. E. HEINS Hydrodynamics and Thermodynamics 87 BY S. R. DE GROOT Nonuniform Propagation of Plane Shock Waves 101 BY J. M. BURGERS Theory of Propellers 109 BY THEODORE THEODORSEN Numerical Methods in Conformal Mapping 117 BY G.
    [Show full text]
  • ;• National Advisory Committee for Aeronautics
    I , / ;• NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS REPORT No. 777 THE THEORY OF PROPELLERS Ill-THE SLIPSTREAM CONTRACTION WITH NUMERICAL VALUES FOR TWO-BLADE AND FOUR-BLADE PROPELLERS By THEODORE THEODORSEN 1944 For sale by the Superintendent of Documents - U. S. Government Printing Office - Washington 20, D. C. - Price 20 cents -S.- AERONAUTIC SYMBOLS 1. FUNDAMENTAL AND DERIVED UNITS Metric English Symbol Unit Abbrevia- Abbrevia- uunit t tion Length 1 meter--------------------m foot (or mile) --------- -ft (or mi) Time -------- --t second ----------------- --s second (or hour) ------- --see (or hr) Force---------- F weight of 1 kilogram kg weight of 1 pound-------lb Power ------- - P horsepower (metric) ----- --------— horsepower-------------hp Speed v f kilometers per hour--------kph miles per hour ---------- mph imeters per second ------- -mps feet per second--------- fps 2. GENERAL SYMBOLS W Weight=mg V Kinematic viscosity g Standard acceleration of gravity=9.80665 rn/s 2 p Density (mass per unit volume) or 32.1740 ft/sec' Standard density of dry air, 0.12497 kg-m-'-s' at 15° 0 W M Mass= — and 760 mm; or 0.002378 lb-ft-4 sec' g Specific weight of "standard" air, 1.2255 kg/ml or I Moment of inertia=mk2. (Indicate axis of 0.07651 lb/cu ft radius of gyration k by proper subscript.) Coefficient of viscosity 3. AERODYNAMIC SYMBOLS S Area ill Angle of setting of wings (relative to thrust line) S. Area of wing it Angle of stabilizer setting (relative to thrust 6' Gap line) b Span (7 Resultant moment C Chord Resultant angular velocity V
    [Show full text]
  • Aeroelasticity and Structural Dynamics
    Aeroelasticity and Structural Dynamics Aeroelasticity and Structural Dynamics he fourteenth issue of AerospaceLab Journal is dedicated to aeroelasticity and T structural dynamics. Aeroelasticity can be briefly defined as the study of the low frequency dynamic behavior of a structure (aircraft, turbomachine, helicopter rotor, etc.) in an aerodynamic flow. It focuses on the interactions between, on the one hand, the static or vibrational deformations of the structure and, on the Cédric LIAUZUN other hand, the modifications or fluctuations of the aerodynamic flow field. (ONERA) Senior Scientist Aeroelastic phenomena have a strong influence on stability and therefore on the integrity of aeronautical structures, as well as on their performance and durability. In the current context, in which a reduction of the footprint of aeronautics on the environment is sought, in particular by reducing the mass and fuel consumption of aircraft, aeroelasticity problems must be taken into account as early as possible in the design of such structures, whether they are conventional or innovative concepts. It is therefore necessary to develop increasingly efficient and accurate numerical and experimental methods and tools, allowing additional complex physical phenomena to be taken into account. On the other hand, the development of larger and lighter aeronautical structures entails the need to determine the dynamic characteristics of such Nicolas PIET-LAHANIER highly flexible structures, taking into account their possibly non-linear behavior (large (ONERA) displacements, for example), and optimizing them by, for example, taking advantage Senior Scientist of the particular properties of new materials (in particular, composite materials). DOI: 10.12762/2018.AL14-00 This issue of AerospaceLab Journal presents the current situation regarding numerical calculation and simulation methods specific to aeroelasticity and structural dynamics for several applications: fan damping computation and flutter prediction, static and dynamic aeroelasticity of aircraft and gust response.
    [Show full text]
  • Hypersonic Aeroelasticity and Aerothermoelasticity With
    12th AIAA International Space Planes and Hypersonic Systems and Technologies AIAA 2003-7014 15 - 19 December 2003, Norfolk, Virginia HYPERSONIC AEROTHERMOELASTICITY WITH APPLICATION TO REUSABLE LAUNCH VEHICLES P.P. Friedmann,¤ J.J. McNamara,y B.J. Thuruthimattam,y and K.G. Powellz Department of Aerospace Engineering University of Michigan 3001 Fran»cois-Xavier Bagnoud Bldg., 1320 Beal Ave Ann Arbor, Michigan 48109-2140 Ph: (734) 763-2354 Fax: (734) 763-0578 email: [email protected] ABSTRACT b Semi-chord c Reference length, chord length of The hypersonic aeroelastic and aerothermoelastic double-wedge airfoil problem of a double-wedge airfoil typical cross-section CD;CL;CMy Coe±cients of drag, lift and moment is studied using three di®erent unsteady aerody- about the y-axis namic loads: (1) third-order piston theory, (2) Euler CpP T ;CpNS Piston theory pressure coe±cient, and aerodynamics, and (3) Navier-Stokes aerodynamics. CFD Navier-Stokes pressure coe±cient Computational aeroelastic response results are used respectively to obtain frequency and damping characteristics, and f(x) Function describing airfoil surface compared with those from piston theory solutions for f1(); fi() Functions relating Mach number and a variety of flight conditions. Aeroelastic behavior is temperature studied for 5 < M < 15 at altitudes of 40,000 and h Airfoil vertical displacement at Elastic 70,000 feet. A parametric study of o®sets, wedge Axis angles, and static angle of attack is conducted. All the I® Mass moment of inertia about the solutions are fairly close below the flutter boundary, Elastic Axis and di®erences between the various models increase K®;Kh Spring constants in pitch and plunge when the flutter boundary is approached.
    [Show full text]
  • Interviw with Homer J. Stewart
    HOMER J. STEWART (1915 - 2007) INTERVIEWED BY JOHN L. GREENBERG October-November 1982 INTERVIEWED BY SHIRLEY K. COHEN November 3, 1993 1979 ARCHIVES CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California Subject area Engineering, aeronautical engineering Abstract Two interviews with Homer J. Stewart, aeronautical engineer and Caltech Professor of Aeronautics, 1942-1980, and Caltech alumnus (PhD, 1940). The interview by John L. Greenburg is in four sessions in October and November of 1982. A supplemental interview was conducted by Shirley K. Cohen in November 1993. The first interview covers Stewart’s youth and education (B.Aero.E., University of Minnesota, 1936) and his early interest in aeronautic technology. Comes to Caltech for graduate study in aeronautics, 1936-1940 (PhD, 1940); courses with faculty members W. Smythe, R. C. Tolman, E. T. Bell, M. Ward, H. Bateman. Comments on critical roles of Theodore von Kármán and Clark Millikan in establishment of graduate program known as GALCIT [Guggenheim Aeronautical Laboratory at the California Institute of Technology]; creation of GALCIT wind tunnel for testing; advancement of aeronautical engineering education; and linking of GALCIT to burgeoning California aerospace industry. Von Kármán’s identification of new technologies; his bridging of industry and http://resolver.caltech.edu/CaltechOH:OH_Stewart_H academe; similar integrating approach applied to founding of Jet Propulsion Laboratory [JPL]. Discusses GALCIT’s role in the development of commercial aviation in the 1930s. Appointment to professorial rank (1942) and wartime teaching and research on meteorology; comments on Irving Krick at Caltech. Discusses beginnings of rocketry at Caltech and his own pioneering contributions; work of Frank Malina and H.
    [Show full text]