DOCSLIB.ORG

Open Ed__Brouwers Masters Thesis 2010 Rev2.Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Open Ed__Brouwers Masters Thesis 2010 Rev2.Pdf The Pennsylvania State University The Graduate School College of Engineering THE EXPERIMENTAL INVESTIGATION OF A ROTOR ICING MODEL WITH SHEDDING A Thesis in Aerospace Engineering by Edward W. Brouwers © 2010 Edward W. Brouwers Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science May 2010 The thesis of Edward W. Brouwers was reviewed and approved* by the following: Jose L. Palacios Post Doctoral Research Associate Edward C. Smith Professor of Aerospace Engineering Thesis Adviser Cengiz Camci Professor of Aerospace Engineering George A. Lesieutre Professor of Aerospace Engineering Head of the Department of Aerospace Engineering *Signatures are on file in the Graduate School. ii ABSTRACT A critical operational problem for rotorcraft is flight in adverse weather conditions. Flight in icing conditions is fraught with operational hazards, including reduced vehicle performance and degraded handling qualities. Additionally, shedding of ice from blades due to centrifugal force poses a ballistics danger to the aircraft and creates large vibrations due to imbalanced rotors. Modeling the effects of accreted ice on rotorcraft flight performance has been a challenge due to the complexities of periodically changing conditions as well as spanwise variations of angle of attack, velocities and surface temperatures. Model validation has been complicated by the lack of available data due to the existence of only a few facilities designed to study the rotorcraft aspect of the icing problem. As part of the development of the Adverse Environment Rotor Test Stand (AERTS), a new icing model was developed to predict ice shapes on a hovering rotor. The AERTS Rotor Icing, Shedding and Performance (ARISP) model has the goal of exploring rotor icing trends. The core feature of the model is the coupling with NASA‟s LEWis ICE accretion code (LEWICE). Rotor performance is predicted with a blade element momentum theory module, while increases in rotor torque due to ice accretions are empirically calculated. A shedding module predicts the shedding time and blade station based upon the accreted ice properties. The ARISP model was correlated with published ice shapes for both small-scale and full- scale rotor ice accretion results. iii Further correlations were made with experiments in the newly developed Adverse Environment Rotor Test Stand (AERTS). These experiments constitute the first ice shape comparisons in the test stand. A total of 44 test cases were completed, of which the first 23 were designed to explore the limitations of the AERTS facility. The remaining 21 cases formed the test matrix for the ARISP model validation and were designed to investigate the influence of various icing parameters. Favorable comparisons have been made between ice shape, especially at inboard stations. Primary ice shape features were predicted well for over 81% of the experimental ice tracings. The largest discrepancies occurred at test cases that did not lie within the FAR Part 25/29 Appendix C icing envelope. Impingement limits were modeled well, with the discrepancies between the limit calculations and experimental values generally lower than 20%. Torque rise predications were generally within 20% of experimental values. Shedding behavior was also evaluated, but correction factors were required to improve test data correlation due to the general overprediction of tip ice accretions. These correction factors were derived from the difference in ice shape between predictions and experiments and reduced prediction error in shedding time to 25% and shedding station to 8%. Further investigations are required, but the icing model has laid the foundation for future research in the AERTS Facility. iv TABLE OF CONTENTS LIST OF FIGURES ............................................................................................................................................ VIII LIST OF TABLES................................................................................................................................................ XII ACKNOWLEDGEMENTS ................................................................................................................................ XIII 1. INTRODUCTION ........................................................................................................................................ 1 1.1 BACKGROUND AND MOTIVATION..................................................................................................................... 1 1.1.1 Icing Overview ..................................................................................................................................... 1 1.1.2 Rotorcraft Challenges ........................................................................................................................... 2 1.1.3 Icing Conditions.................................................................................................................................... 5 1.2 REVIEW OF RELATED WORK .......................................................................................................................... 14 1.2.1 Ice Accretion Facilities ....................................................................................................................... 14 1.2.2 Ice Accretion Prediction Codes ......................................................................................................... 19 1.3 OBJECTIVES .................................................................................................................................................... 23 1.4 THESIS OVERVIEW ......................................................................................................................................... 24 1.4.1 Chapter 2: Ice Accretion and Shedding Model ................................................................................. 24 1.4.2 Chapter 3: AERTS Facility Calibration .............................................................................................. 25 1.4.3 Chapter 4: Ice Adhesion Strength Calculation Fixture ..................................................................... 25 1.4.4 Chapter 5: Experimental Exploration of ARISP Model in AERTS Facility ..................................... 25 1.4.5 Chapter 6: Conclusions and Recommendations ................................................................................ 25 1.4.6 Appendices .......................................................................................................................................... 26 2. ICE ACCRETION MODELING – ARISP CODE ........................................................................................ 27 2.1 OBJECTIVES .................................................................................................................................................... 27 2.2 ARISP CODE OVERVIEW ............................................................................................................................... 28 2.2.1 Software .............................................................................................................................................. 29 2.3 ANALYSIS CONCEPT AND IMPLEMENTATION .................................................................................................. 31 2.3.1 Hover Performance – BEMT .............................................................................................................. 32 2.3.2 LEWICE Integration ........................................................................................................................... 39 2.3.3 Ice Shedding ........................................................................................................................................ 45 2.3.4 Iced Rotor Performance Degradation ................................................................................................ 51 2.3.5 Initial ARISP Model Validation ......................................................................................................... 55 3. AERTS FACILITY DESIGN, CONSTRUCTION AND CALIBRATION ..................................................... 63 3.1 REQUIREMENTS .............................................................................................................................................. 63 3.2 CFD MODELING OF THE AERTS CHAMBER ................................................................................................... 64 3.2.1 Objectives ............................................................................................................................................ 64 3.2.2 Model Setup ........................................................................................................................................ 64 3.2.3 Model Results ...................................................................................................................................... 66 3.2.4 Modeling Conclusions ........................................................................................................................ 74 3.3 ICING CLOUD CALIBRATION ........................................................................................................................... 75 3.3.1 Temperature ........................................................................................................................................ 75 3.3.2 Droplet Size ........................................................................................................................................
Load more

Recommended publications
  • Book Reviews the SYCAMORE SEEDS
    Afterburner Book Reviews THE SYCAMORE SEEDS Early British Helicopter only to be smashed the following night in a gale. The book then covers the Cierva story in some detail, the Development chapter including, out of context, two paragraphs on By C E MacKay the Brennan propeller-driven rotor driven helicopter [helicogyro] fl own in 1924 at Farnborough but Distributed by A MacKay, 87 Knightscliffe Avenue, aborted by the Air Ministry the next year, stating that Netherton, Glasgow G13 2RX, UK (E charlese87@ there was no future for the helicopter and backing btinternet.com). 2014. 218pp. Illustrated. £12.95. Cierva’s autogyro programme contracting Avro to build ISBN 978-0-9573443-3-4. the fi rst British machines. Good coverage is given to the range of Cierva autogyros culminating in the Avro Given the paucity of coverage of British helicopter C30 Rota and its service use by the RAF. development I approached this slim (218 A5 pp) The heart of the book begins with a quotation: publication with interest. While autogyros have been “Morris, I want you to make me blades, helicopter well documented, Charnov and Ord-Hume giving blades,” with which William Weir, the fi rst Air Minister, exhaustive and well documented treatments of the founder of the RAF and supporter of Cierva, brought helicopter’s predecessor, the transition to the directly furniture maker H Morris & Co into the history of driven rotor of the helicopter is somewhat lacking. rotorcraft pulling in designers Bennett, Watson, Unfortunately MacKay’s book only contributes a Nisbet and Pullin with test pilots Marsh and Brie fi nal and short chapter to the ‘British Helicopter’ to form his team.
    [Show full text]
  • Over Thirty Years After the Wright Brothers
    ver thirty years after the Wright Brothers absolutely right in terms of a so-called “pure” helicop- attained powered, heavier-than-air, fixed-wing ter. However, the quest for speed in rotary-wing flight Oflight in the United States, Germany astounded drove designers to consider another option: the com- the world in 1936 with demonstrations of the vertical pound helicopter. flight capabilities of the side-by-side rotor Focke Fw 61, The definition of a “compound helicopter” is open to which eclipsed all previous attempts at controlled verti- debate (see sidebar). Although many contend that aug- cal flight. However, even its overall performance was mented forward propulsion is all that is necessary to modest, particularly with regards to forward speed. Even place a helicopter in the “compound” category, others after Igor Sikorsky perfected the now-classic configura- insist that it need only possess some form of augment- tion of a large single main rotor and a smaller anti- ed lift, or that it must have both. Focusing on what torque tail rotor a few years later, speed was still limited could be called “propulsive compounds,” the following in comparison to that of the helicopter’s fixed-wing pages provide a broad overview of the different helicop- brethren. Although Sikorsky’s basic design withstood ters that have been flown over the years with some sort the test of time and became the dominant helicopter of auxiliary propulsion unit: one or more propellers or configuration worldwide (approximately 95% today), jet engines. This survey also gives a brief look at the all helicopters currently in service suffer from one pri- ways in which different manufacturers have chosen to mary limitation: the inability to achieve forward speeds approach the problem of increased forward speed while much greater than 200 kt (230 mph).
    [Show full text]
  • ELECTRIC ROTARY WING AIRCRFTS. [3290] Field of Invention Relates to Rotary Wing Aircrafts and the Like. This Invention Relates T
    ELECTRIC ROTARY WING AIRCRFTS. [3290] Field of invention relates to rotary wing aircrafts and the like. This invention relates to vertical propulsion turbine motors and generators combined including a digital glass cabin and manual navigation controllers consisting of a sphere or ball mounting in bearing in the stator casing and electrically connected with the flyby wire system. Helicopters and modern rotary wing aircraft and more particularly to helicopters with reduced blade length and increased speed and maneuverability with increased RPM. [3291] Combined propulsion and generator with linear rotors and perpendicular rotors. Helicopter in which in-plane Description of the prior art Sustainable and Zero emission helicopter with new means for navigating and power generating for electric flying vehicles. With wind turbines integrated in the duct and a steam turbine generator in a compressed machine casing electrically connected to the power supply. BACKGROUND OF THE INVENTION [3292] Conventional rotary wing aircraft are driven by combustion engines and are limited in application by rendering the aerial vehicles electric and digital with zero emission. Consisting rotary wing aircrafts ar helicopters and utility aerial vehicles, privet transport chopper, is a type of rotorcraft in which lift and thrust are supplied by propeller rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of VTOL (Vertical Takeoff and Landing) aircraft cannot perform. The Electric aircraft is navigated by the main rotor and tail rotor and turbine engines and boosters comprising electric generators for power supply.
    [Show full text]
  • Aerodynamic Concept of the Uav in the Gyrodyne Configuration
    TRANSACTIONS OF THE INSTITUTE OF AVIATION 1 (250) 2018, pp. 49–66 DOI: 10.2478/tar-2018-0005 © Copyright by Wydawnictwa Naukowe Instytutu Lotnictwa AERODYNAMIC CONCEPT OF THE UAV IN THE GYRODYNE CONFIGURATION Jan Muchowski*, Marek Szumski*, Andrzej Krzysiak** *Department of Fluid Mechanics and Aerodynamics, Mechanical Engineering and Aeronautics, Rzeszow University of Technology, al. Powstańców Warszawy 8, 35-959 Rzeszow **Aerodynamics Department, Institute of Aviation, Al. Krakowska 110/114, 02-256 Warsaw [email protected], [email protected], [email protected], Abstract The article presents an aerodynamic concept of UAV in the gyrodyne configuration, as a more efficient one than the currently used UAV airframe configuration applied for monitoring tasks of pow- er lines and railway infrastructure. A sample task which is realised by conceptual gyrodyne based on monitoring aerial power lines was characterised and described . The assumed idea of UAV was shown in comparison to the currently used aircraft configuration presented in the introduction. Referring to momentum theory, hover efficiency of the multicopter and the helicopter was evaluated. In relation to the helicopter, an initial draft of the airframe conception accompanied by a description of advan- tages of the gyrodyne configuration was exposed. Problems related to the gyrodyne configuration were emphasised in the summary. Keywords: aerodynamic concept, UAV, VTOL, gyrodyne, airframe configuration 1. INTRODUCTION In recent years a dynamic growth of the UAV (Unmanned Aerial Vehicle) usage in civil and mili- tary missions can be observed . Economic aspects are the main reasons of that increase, i.e. the purchas- ing cost of the UAS (Unmanned Aircraft System) varies from 40% up to 80% of the manned system cost.
    [Show full text]
  • Helicopter Controllability. Reference 2 Presents a Comprehensive History and References 1 and 3 Present Summarized Histories of Helicopter Development
    Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection 1989-09 Helicopter controllability Carico, Dean Monterey, California. Naval Postgraduate School http://hdl.handle.net/10945/27077 DTfltttf NAVAL POSTGRADUATE SCHOOL Monterey , California THESIS C2D L/5~ HELICOPTER CONTROLLABILITY by Dean Carico September 1989 Thesis Advisor: George J. Thaler Approved for public release; distribution unlimited lclassified V CLASSi^'CATiON QF THIS PAGE REPORT DOCUMENTATION PAGE ORT SECURITY CLASSIFICATION 1b RESTRICTIVE MARKINGS assif ied IURITY CLASSIFICATION AUTHORITY 3 DISTRIBUTION /AVAILABILITY OF REPORT Approved for public release :lassification t DOWNGRADING SCHEDULE Distribution is unlimited ORMING ORGANIZATION REPORT NUMBER(S) 5 MONITORING ORGANIZATION REPORT NUMBER(S) ME OF PERFORMING ORGANIZATION 6b OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION il Postgraduate School (If applicable) 62 Naval Postgraduate School DRESS {City, State, and ZIP Code) 7b ADDRESS (C/fy, State, and ZIP Code) :erey, California 93943-5000 Monterey, California 93943-5000 9 PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER DRESS (City, State, and ZIP Code) 10 SOURCE OF FUNDING NUMBERS IE (include Security Claudication) HELICOPTER CONTROLLABILITY RSONAL AUTHOR(S) ICO, G. Dean YPE OF REPORT 4 DATE OF REPORT (Year, Month. Day) ter ' s Thesis 1989, September ipplementary notation T h e views expressed in this thesis are thos e of the hor and do not reflect the official policy or position of the Department r,nyprninpnf npfpnsp nr ___ , COSATi CODES 18 SUBJECT TERMS {Continue on reverse if pecessary and identify Helicopter Controllability, Helicop Flight Control Systems, Helicopter Flying Qualities and Flying Qualities Spec if ications i 3STRACT {Continue I reverse if necessary and identify by block number) 'he concept of helicopter controllability is explained.
    [Show full text]
  • Helicopters in the Royal Air Force
    ROYAL AIR FORCE HISTORICAL SOCIETY JOURNAL 25 2 The opinions expressed in this publication are those of the contributors concerned and are not necessarily those held by the Royal Air Force Historical Society. Photographs credited to MAP have been reproduced by kind permission of Military Aircraft Photographs. Copies of these, and of many others, may be obtained via http://www.mar.co.uk Copyright 2001: Royal Air Force Historical Society First published in the UK in 2001 by the Royal Air Force Historical Society All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopying, recording or by any information storage and retrieval system, without permission from the Publisher in writing. ISSN 1361-4231 Typeset by Creative Associates 115 Magdalen Road Oxford OX4 1RS Printed by Professional Book Supplies Ltd 8 Station Yard Steventon Nr Abingdon OX13 6RX 3 CONTENTS THE PROCEEDINGS OF THE RAFHS SEMINAR ON 7 HELICOPTERS IN THE ROYAL AIR FORCE BOOK REVIEWS 112 4 ROYAL AIR FORCE HISTORICAL SOCIETY President Marshal of the Royal Air Force Sir Michael Beetham GCB CBE DFC AFC Vice-President Air Marshal Sir Frederick Sowrey KCB CBE AFC Committee Chairman Air Vice-Marshal N B Baldwin CB CBE FRAeS Vice-Chairman Group Captain J D Heron OBE Secretary Group Captain K J Dearman Membership Secretary Dr Jack Dunham PhD CPsychol AMRAeS Treasurer Desmond Goch Esq FCCA Members Air Commodore H A Probert MBE MA *J S Cox Esq BA MA *Dr M A Fopp MA FMA FIMgt *Group Captain P Gray
    [Show full text]
  • The Evolution of the British Rotorcraft Industry 1842-2012
    Journal of Aeronautical History Paper No. 2012/07 THE EVOLUTION OF THE BRITISH ROTORCRAFT INDUSTRY 1842-2012 Eur Ing David Gibbings C Eng., FRAeS Based on a paper originally presented to the European Rotorcraft Forum in Hamburg, September 2009. ABSTRACT This paper relates the way in which rotorcraft developed in Britain, leading to the growth of an effective design and manufacturing industry. The narrative is divided into five sections, each of which represents defining phases in UK based activity leading towards the development of the modern helicopter: 1. The Pre-Flight Period (1842-1903) This section covers British activity during the period when the objective was simply to demonstrate powered flight by any means, and where rotors might be considered to be a way of achieving this. 2. The Early Helicopter Period (1903-1926). Early attempts to build helicopters, including the work of Louise Brennan, which achieved limited success with a rotor driven by a propellers mounted on the blade tips. 3. The Pre-War Years (1926-1939) This section gives emphasis to development of the gyroplane and in particular the work of Juan de la Cierva, with his UK-based company to develop his 'Autogiro', from which the understanding of rotor dynamics and control was established, and which was to lead to the realisation of the helicopter by others. Although UK rotary wing development was driven by the gyroplane, the work carried out by the Weir Company, which was to lead to the first successful British helicopter is discussed. 4. The War Years. (1939-1945) Rotary wing activities in the UK were very limited during World War 2, restricted to the work carried out by Raoul Hafner with the Rotachute/ Rotabuggy programme and the use of autogiros for the calibration of radar.
    [Show full text]
  • Advantageous Autorotation
    The DARPA Heliplane aimed to Advantageous double helicopter performance in a VTOL platform without the complexity of a helicopter transmission or anti-torque system. Autorotation (All images via Skyworks Global) Skyworks Global plans to commercialize affordable autorotating aircraft in regions without aviation infrastructure and looks to revive DARPA Heliplane technology for speed, range and vertical takeoff. By Frank Colucci hile sustained autorotative flight found a lasting market in recreational gyroplanes, the technology Whas broader potential. Skyworks Global last year re- branded the Groen Aeronautics line of gyrocraft and plans to What’s in a Name? commercialize the technology for more users — this summer with the SparrowHawk III kit gyroplane, then with the larger Autogiro: the original term, trademarked and licensed by Juan de la Cierva, for an aircraft using an Hawk 5 gyroplane built offshore, and potentially with big, tip-jet- autorotating rotor for lift plus one or more propellers driven gyrodynes that can take off and land vertically and hover. for thrust. “What we’re going to solve is two-thirds of the world’s aviation autogyro: the general term for an autorotating requirements,” stated Skyworks’ executive committee director, aircraft, particularly one that was not a licensed retired US Air Force Brig. Gen. John Michel. “No one has paid Cierva Autogiro. The FAA recognizes the name attention to the two-thirds of the world with no infrastructure, “gyroplane” instead. no educated workforce — gyrocraft are built for that.” Skyworks AutoGyro: a German company that produces over Global’s “simple, elegant solution” of a freewheeling rotor with 300 gyroplanes annually. collective pitch control is protected by patents to make gyrocraft Gyrocopter: this term was trademarked by Igor safer and more flexible.
    [Show full text]
  • PDF Download Hovering Helicopters
    HOVERING HELICOPTERS PDF, EPUB, EBOOK Molly Aloian | 32 pages | 15 Sep 2010 | Crabtree Publishing Co,Canada | 9780778730620 | English | New York, Canada Hovering Helicopters PDF Book His writings on his experiments and models would become influential on future aviation pioneers. Oil companies charter helicopters to move workers and parts quickly to remote drilling sites located at sea or in remote locations. His notes suggested that he built small flying models, but there were no indications for any provision to stop the rotor from making the craft rotate. During the closing years of the 20th century designers began working on helicopter noise reduction. Guinness World Record. Retrieved 24 September American inventor Arthur M. Tilts main rotor disk forward and back via the swashplate. From design, engineering and production, to maintenance, training and partnerships, Airbus is focused on meeting and exceeding industry safety standards and supporting the flight safety for the thousands of men and women around the world who are transported in its aircraft every day. Special jet engines developed to drive the rotor from the rotor tips are referred to as tip jets. These issues are due to the exposed tail rotor cutting through open air around rear of the vehicle. Most also have vibration dampers for height and pitch. For other uses, see Helicopter disambiguation. The rotor consists of a mast, hub and rotor blades. On 25 July , the Japanese bulk carrier Wakashio ran aground on a coral reef in Mauritius. Two Army National Guard helicopters flew low over the protesters, with the downward blast from their rotor blades sending protesters scurrying for cover and ripping signs from the sides of buildings.
    [Show full text]
  • Appendix a Comparison of Coaxial, Tandem and Single Rotor Helicopter Types
    THE UNIVERSITY OF QUEENSLAND Development of a UAV Rotorcraft Design Software Framework Using an Aeromechanics Design Analysis Student Name: Rowan CONAGHAN Course Code: MECH4500 Supervisor: Dr Ingo Jahn, Senior Lecturer in Mechanical Engineering Submission date: 25 October 2018 Faculty of Engineering, Architecture and Information Technology P a g e | iv This page is intentionally left blank P a g e | v DECLARATION All work contained here within is my own work unless explicitly stated. P a g e | vi This page is intentionally left blank P a g e | vii DEDICATION “Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.” – Leonardo Da Vinci [1] . Ever since my first flight in a Boeing-737 when I was a child, I have dreamt about reaching for the skies, flapping my arms and soaring high above the earth. Flight had dawned mankind for many millennia, and has been at the forefront of my mind ever since my youth; and my first taste of it. In the words of Leonardo Da Vinci, I yearn to return. As such I have taken every step since my later school years developing the knowledge and expanding upon it. This thesis is dedicated to my family who have supported me so extensively throughout my early development and my schooling career. To my parents, Anthony and Karen Conaghan; without your constant love, support and guidance, I wouldn’t be the person I am today. I dedicate this work to you.
    [Show full text]
  • An Integrated Framework for Innovative Compound Gyroplane Design System
    28TH INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES AN INTEGRATED FRAMEWORK FOR INNOVATIVE COMPOUND GYROPLANE DESIGN SYSTEM Tun Lwin*, Ngoc Anh Vu*, Kim Jimin*, Jae-Woo Lee*, Sangho Kim*, Young Jae Lee** *Konkuk University, Seoul, Korea 143-701, **Hanwha Corporation R&D Center, Seoul Korea 138-740 [email protected];[email protected],[email protected],[email protected], [email protected] Keywords: Compound gyroplane design, Database, System Integration Abstract required such as sizing, performance, trim and flight mechanics. A compound gyroplane is an In this paper, the integration of compound aircraft which has an auto-rotational rotor and gyroplane designer system has been studied and fixed wing. Therefore, loads of rotor blades can developed. A comprehensive compound be reduced in high speed cruise flight, and the gyroplane designer system (CCGD) integrates thrust can be obtained by turbofan or turboprop the design program with CATIA configuration engines. For example, ‘Carter Copter’ is and X-Plane simulation program. The design developed from Carter Aviation Technologies related data are managed by the centralized Company in the US1. database management system. The database In author’s previous studies, the KHDP also controls integrity of data, integrity of (Korea Helicopter Design Program) was reference and security of data. To develop a implemented using a design analysis program graphical user interface (GUI), VB.Net and together with Graphical User Interface (GUI). Microsoft .Net 2008 classes are used. The KHDP uses FORTRAN programming language design analysis module considers sizing for design analysis and Visual Basic 6.0 for GUI program for analyzing configuration and weight implementation.
    [Show full text]
  • A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research 1997
    NASA Technical Paper 3675 A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research 1997 Colin P. Coleman, Ames Research Center, Moffett Field, California National Aeronautics and Space Administration Ames Research Center Moffett Field, California 94035-1000 Contents Page List of Figures ........................................................................................................................................................... V Nomenclature ............................................................................................................................................................ vii Summary .................................................................................................................................................................... 1 Introduction ............................................................................................................................................................... 1 Definitions ................................................................................................................................................................ 2 Research in the United States of America ................................................................................................................ 2 NACA Langley Research Center ...................................................................................................................... 2 De Lackner Helicopters, Inc .............................................................................................................................
    [Show full text]