Gust Loads on Aircraft: Concepts & Applications

320 Pages·2001·16.91 MB·English

by  Frederic M. Hoblit

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Gust Loads on Aircraft:
Concepts and Applications
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4/ Frederic M. Hoblit
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25 Consultant
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DOI: Formerly,
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n AIAA EDUCATION SERIES
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O Air Force Institute of Technology
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UN Wright-Patterson Air Force Base, Ohio
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oa This volume was sponsored by the Lockheed Aeronautical
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Lockheed Report
Published by
American Institute of Aeronautics and Astronautics, Inc.
370 L'Enfant Promenade, S.W., Washington, D.C. 20024
Texts Published in the AIAA Education Series
Re-Entry Vehicle Dynamics
Frank J. Regan, 1984
Aerothermodynamics of Gas Turbine and Rocket Propulsion
Gordon C. Gates, 1984
Aerothermodynamics of Aircraft Engine Components
Gordon C. Gates, Editor, 1985
Fundamentals of Aircraft Combat Survivability Analysis and Design
Robert E. Ball, 1985
8 Intake Aerodynamics
8
8
1 J. Seddon and E. L. Goldsmith, 1985
6
8
4. Composite Materials for Aircraft Structures
4/
1 Brian C. Hoskin and Alan A. Baker, Editors, 1986
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0.2 Gasdynamics: Theory and Applications
1
OI: George Emanuel, 1986
D Aircraft Engine Design
org | Jack D. Mattingly, William Reiser, and Daniel H. Daley, 1987
aa. An Introduction to the Mathematics and Methods of Astrodynamics
c.ai Richard H. Battin, 1987
p://ar Radar Electronic Warfare
htt August Golden Jr., 1988
3 | Advanced Classical Thermodynamics
1
20 George Emanuel, 1988
e 4, Aerothermodynamics of Gas Turbine and Rocket Propulsion, Revised and Enlarged
n
n Ju Gordon C. Gates, 1988
o Re-Entry Aerodynamics
A
R Wilbur L. Hankey, 1988
O
O Mechanical Reliability: Theory, Models and Applications
D
N B. S. Dhillon, 1988
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B Aircraft Landing Gear Design: Principles and Practices
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NI Norman S. Currey, 1988
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MIT American Institute of Aeronautics and Astronautics, Inc., Washington, DC
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b Library of Congress Cataloging-in-Publication Data
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oa Hoblit, Frederic M.
nl Gust loads on aircraft: concepts and applications
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p. cm.—(AIAA education series)
Bibliography: p.
Includes index.
1. Airplanes—Design and construction. 2. Gust loads. I. Title. II. Series.
TL671.2.H58 1988 629.132'3—dc!9 88-8146 CIP
ISBN 0-930403-45-2
Copyright © 1988 by the American Institute of Aeronautics and Astronautics, Inc. All rights
reserved. Printed in the United States of America. No part of this publication may be
reproduced, distributed, or transmitted, in any form or by any means, or stored in a data base
or retrieval system, without prior written permission of the publisher.
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3 | To My Lockheed Mentors,
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FOREWORD
One of the objectives of the AIAA Education Series is to provide archival
8 documentation of the established practices in aircraft design. Gust Loads on
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18 Aircraft: Concepts and Applications by Frederic M. Hoblit is in this special
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4.8 category; it provides an authoritative exposition of the current engineering
14/ practice of determining gust loads on airplanes, especially the continuous-
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0.2 turbulence gust loads.
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D the gust structure, including the subject of static and dynamic discrete-gust
org | loads, and then moves on to the more modern power-spectral, or continu-
aa. ous-turbulence, concepts and methods. This newer approach has gained
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htt quently used to verify structural integrity of the airplane.
13 | Because of the relative unfamiliarity of an average reader with the
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4, power-spectral methods, all the necessary mathematical concepts and meth-
ne ods are provided in the text. The continuous-turbulence gust loads criteria
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BU treatment of nonlinear systems, and analysis of gust-response flight-test
NIV data. The final chapter addresses the overall philosophy of discrete-gust
U concepts and their present applications.
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MI This latest text in the AIAA Education Series provides a unique source
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a supplementary text for courses in aeroelasticity, flight mechanics, and flight
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J. S. PRZEMIENIECKI
Editor-in-Chief
AIAA Education Series
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TABLE
OF
CONTENTS
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4.8 xi Preface
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10. 1 Chapter 1. Gust Loads Fundamentals
OI: 1.1 Mechanism of Gust Loads Generation
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3 | 2.3 FAR Gust Loads Formula
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4.2 Measure of Intensity: RMS Value of y
4.3 Probability Distribution
4.4 Frequency Content and Power-Spectral Density (PSD)
4.5 Gust PSD for Use in Design
4.6 Frequency of Exceedance
4.7 Application of Frequency of Exceedance to Gust Loads
4.8 Determination of P's and b's from Flight Data
4.9 Relation Between Frequency of Exceedance and
Probability of Exceedance
Problems
69 Chapter 5. Continuous Turbulence Gust Loads Criteria
5.1 FAR Requirements
5.2 Military Requirements
5.3 Basic Forms of Criterion
5.4 Design Levels
5.5 Flight Profile Generation
5.6 Modification of Design Envelope Criterion to Account
for NQ
5.7 Combined Vertical and Lateral Gust Loads
5.8 Stability Augmentation or Active Control System (ACS)
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4.8 97 Chapter 6. Load Combinations and Design Conditions
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a.or and Solution
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3 | 7.4 Use of Matrices and Matrix Algebra
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BU 123 Chapter 8. Short-Cut Methods
NIV 8.1 Plunge-Only Curves
U 8.2 Plunge-Pitch Curves: Hoblit Parameters
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8.7 Empirical Adjustments
Problems
165 Chapter 9. Spanwise Variation of Vertical Gust Velocity
9.1 Introduction
9.2 Applications of Three-Dimensional Gust Analysis
9.3 Effect of Three-Dimensional Gust Analysis on Loads
9.4 Effect of L on Three-Dimensional Gust Response
169 Chapter 10. Treatment of Nonlinear Systems
10.1 Sources of Nonlinearities
10.2 Use of Time-History Analysis
10.3 Simplifications Made
10.4 Gust Velocity Time History
10.5 Interpretation of Results
173 Chapter 11. Analysis of Gust-Response Flight-Test Data
8 11.1 Purpose of Gust-Response Flight Testing
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MIT 13.1 Nature of Atmospheric Turbulence
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203 Appendix A: Plunge-Only Equation of Motion for an Airplane
Encountering a One-Minus-Cosine Vertical Gust
209 Appendix B: Elementary Introduction to Some Concepts in
Probability Theory and Statistics
B.I Probability of a Single Event
B.2 Some Basic Rules of Probability
B.3 Probability Distribution
B.4 Frequency of Exceedance