DOCSLIB.ORG

THE GREAT PTERODACTYL PROJECT the Largest Ornithopter

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
THE GREAT PTERODACTYL PROJECT the Largest Ornithopter FEATURE ARTICLE THE GREAT PTERODACTYL PROJECT June 1986 R/C Modeler Feature Article Vol. 23 No. 6 Pg. 10 Site Sponsor: Hobby Lobby THE GREAT PTERODACTYL Article Sponsors: PROJECT Morris Hobbies The Largest Ornithopter To Ever Fly By Dick Tichenor A lifelike, radio controlled flying replica of the giant prehistoric pterodactyl Quetzalcoatlus northropi was demonstrated for the press at a special briefing and demonstration at the Greater Los Angeles Press Club. The fully articulated flapping wing replica is the largest ornithopter to ever fly successfully and was created by Aero Vironment, Inc., under the direction of noted aviation pioneer Dr. Paul MacCready. The creature has an 18-foot wingspan, weighs 44 pounds, and is controlled by a complex onboard autopilot system under the command of a ground based operator using a model airplane radio control system. r-fe-ptero-061986-1.html[8/3/2018 1:26:48 PM] The replica, called On The Time Traveler® was developed for a major role in the "On The Wing," a new large screen IMAX© film now in post production for the Smithsonian Institution's National Air and Space Museum in Washington, D.C. The greatest problem the team faced was to develop the means to give the creature stability and control. "Very little is known about how natural fliers such as birds combine their sensing devices, brains and muscles to fly effectively," MacCready said. "The challenge is especially difficult with this pterodactyl replica: The original creature did not even have a tail to help with stability and control." To overcome these problems, the Aero Vironment engineers had to develop and program a special onboard autopilot system. "In response to the computer, the QN replica maintains stable flight by moving its head from side to side, extending its fingers midway out on the wings, twisting its wings and swinging them forward and backward. All this occurs while the battery powered muscles flap the wings to provide propulsion." Development of the pterodactyl replica began in December, 1984. The original plan was to create a 36-foot wingspan replica, patterned after fossilized remains of the largest known pterodactyl that were discovered in West Texas in the 1970s. According to MacCready, however, the half-scale 18-foot version has achieved virtually all of the goals outlined in the original project report released in December, 1984. Those goals included the following: • That the replica fly realistically, propelling itself by wing flapping. • That it be fully controllable in normal flying conditions. • That it use an electric power system that would allow for several minutes of powered flight. Quite a few materials were considered for the pterodactyl's structure including aluminum, spruce, and plywood. The ultimate selection included a widespread usage of carbon fiber. Various shapes (tubes, angles, etc.) were precisely made in the Aero Vironment shop by their craftsmen, This material provided the strength of steel at one-fifth the weight r-fe-ptero-061986-1.html[8/3/2018 1:26:48 PM] Primary power comes from two powerful samarium cobalt electric motors. The motors draw energy from nickel cadmium battery packs to produce a full horsepower each. These motors drive the jack shaft that flaps the wings. A third, smaller, motor mounted toward the rear of the body controls the fore and aft sweep needed as the wings flap. Aero Vironment crew transport the pterodactyl to launch position. To reduce stress on the motors, the pterodactyl specialists designed an ingenious counter tension system basically a set of 66 rubber band "muscles" running from the jack shaft up r-fe-ptero-061986-1.html[8/3/2018 1:26:48 PM] through the lizard's neck. When the wings flap up or down, a cord winds onto a spindle and stretches the bands. That provides a counter tension on the motor so that the wings always return in the opposite direction of where they are. The Cobalt 60 and 05 electric motors were provided by Astro Flight, Inc., renowned leaders in the RIG electric flight activity. Getting the reptile replica airborne was only one more of the many challenges to solve. A two-wheeled dolly containing a tail boom with conventional vertical and horizontal surfaces was devised. When towed behind a van, the machine lifts off and is guided to altitude. When the desired height has been reached, the dolly is released and the normal flight operations take over. Last minute launch preparations with cameraman and director on the ready. So sophisticated are the computer controlled autopilots that a standard model aircraft radio system is used unmodified - to control the pterodactyl's flight. The ground controller uses the system to initiate turns and altitude changes and during take-offs and landings. To land, the creature slides onto its reinforced chest and belly, which serve as a skid. (Left) The wing-flapping mechanism consists of 2 one horsepower samarium-colbalt DC motors which drive the flapping through a gear box and ball screw drive. The mechanism is normally powered by six lbs. of nickel cadium batteries. (Right) The finger motions of the hand halfway out the wing acts as spoilers and drag breaks and operate on only one wing at a time to provide yawing moments. Each finger is driven by a small model airplane servo. r-fe-ptero-061986-1.html[8/3/2018 1:26:48 PM] Sequences involving the creature were filmed at The Racetrack Dry Lake and Ubehebe Crater in Death Valley, California. The film, produced by Francis Thompson, Inc., explores the dynamic relationship between natural and mechanical flight, contrasting the biological evolution of winged creatures with the technological innovation of man. "On The Wing" will premiere at the Museum's Samuel P. Langley Theater on June 20, 1986 and will open subsequently in IMAX© and OMNIMAX© theaters worldwide. The first public flight of the pterodactyl replica is scheduled to take place in Washington, D.C., in mid-June to coincide with the premiere. All Contents Copyright © 1986. R/C Modeler Corporation. All Rights Reserved. Go to Top of Page r-fe-ptero-061986-1.html[8/3/2018 1:26:48 PM].
Load more

Recommended publications
  • Guide to the Paul Maccready Innovative Lives Presentation
    Guide to the Paul MacCready Innovative Lives Presentation NMAH.AC.0842 Alison Oswald 2003 Archives Center, National Museum of American History P.O. Box 37012 Suite 1100, MRC 601 Washington, D.C. 20013-7012 [email protected] http://americanhistory.si.edu/archives Table of Contents Collection Overview ........................................................................................................ 1 Administrative Information .............................................................................................. 1 Scope and Contents........................................................................................................ 2 Biographical / Historical.................................................................................................... 2 Names and Subjects ...................................................................................................... 2 Container Listing ............................................................................................................. 3 Series : Original Videos (OV 842.1-9), 2002-11-08................................................. 3 Series : Reference Videos, 2002-11-08................................................................... 4 Series 3: Digital images, 2002-11-08....................................................................... 5 Paul MacCready Innovative Lives Presentation NMAH.AC.0842 Collection Overview Repository: Archives Center, National Museum of American History Title: Paul MacCready Innovative Lives Presentation Identifier:
    [Show full text]
  • IGC Plenary 2005
    Agenda of the Annual Meeting of the FAI Gliding Commission To be held in Lausanne, Switzerland on 5th and 6th March 2010 Agenda for the IGC Plenary 2010 Day 1, Friday 5th March 2010 Session: Opening and Reports (Friday 09.15 – 10.45) 1. Opening (Bob Henderson) 1.1 Roll Call (Stéphane Desprez/Peter Eriksen) 1.2 Administrative matters (Peter Eriksen) 1.3 Declaration of Conflicts of Interest 2. Minutes of previous meeting, Lausanne, 6th-7th March 2009 (Peter Eriksen) 3. IGC President’s report (Bob Henderson) 4. FAI Matters (Mr.Stéphane Desprez) 4.1 Update by the Secretary General 5. Finance (Dick Bradley) 5.1 2009 Financial report 5.2 Financial statement and budget 6. Reports not requiring voting 6.1 OSTIV report (Loek Boermans) Please note that reports under Agenda items 6.2, 6.3 and 6.4 are made available on the IGC web-site, and will not necessarily be presented. The Committees and Specialists will be available for questions. 6.2 Standing Committees 6.2.1 Communications and PR Report (Bob Henderson) 6.2.2 Championship Management Committee Report (Eric Mozer) 6.2.3 Sporting Code Committee Report (Ross Macintyre) 6.2.4 Air Traffic, Navigation, Display Systems (ANDS) Report (Bernald Smith) 6.2.5 GNSS Flight Recorder Approval Committee (GFAC) Report (Ian Strachan) 6.2.6 FAI Commission on Airspace and Navigation Systems (CANS) Report (Ian Strachan) Session: Reports from Specialists and Competitions (Friday 11.15 – 12.45) 6.3 Working Groups 6.3.1 Country Development Report (Alexander Georgas) 6.3.2 Grand Prix Action Plan (Bob Henderson) 6.3.3 History Committee (Tor Johannessen) 6.3.4 Scoring Working Group (Visa-Matti Leinikki) 6.4 IGC Specialists 6.4.1 CASI Report (Air Sports Commissions) (Tor Johannessen) 6.4.2 EGU/EASA Report (Patrick Pauwels) 6.4.3 Environmental Commission Report (Bernald Smith) 6.4.4 Membership (John Roake) 6.4.5 On-Line Contest Report (Axel Reich) 6.4.6 Simulated Gliding Report (Roland Stuck) 6.4.7 Trophy Management Report (Marina Vigorita) 6.4.8 Web Management Report (Peter Ryder) 7.
    [Show full text]
  • DR. PAUL MACCREADY September 29, 1925 - August 28, 2007 AMA #626304
    The AMA History Project Presents: Biography of DR. PAUL MACCREADY September 29, 1925 - August 28, 2007 AMA #626304 Transcribed & Edited by SS (08/2002); Update by JS (02/2017) Career: . Set many model airplane records . First soloed in a powered plane at age 16 . Flew in the U.S. Navy flight-training program during World War II . 1947: Graduated with a Bachelor of Science degree in physics from Yale University . Won second place in the National Soaring Contest at Wichita Falls, Texas, at age 21 . 1948, 1949, 1953: Won the U.S. National Soaring Championships . Pioneered high-altitude wave soaring in the U.S. 1956: Became the first American to be an international sailplane champion at a meet in France; represented the U.S. in Europe four times . Invented the MacCready speed ring used worldwide by glider pilots . Earned his master’s degree in physics in 1948 and his doctorate degree in aeronautics in 1952, both from the California Institute of Technology . 1971: Started AeroVironment, Inc. Won a few Henry Kremer Prizes for his cutting-edge designs of planes, such as planes powered by human power only . Early 1980s: Developed solar-powered planes . Received various honors and awards and is affiliated with the National Academy of Engineering, the American Academy of Arts and Sciences, the American Institute of Aeronautics and Astronautics and the American Meteorological Society . Served as the international president of the International Human Powered Vehicle Association . Wrote many articles, papers and reports dealing with physics and aeronautics . 2016 AMA Model Aviation Hall of Fame inductee This biography, written in 1986, is stored in the AMA History Project (at the time called the AMA History Program) files.
    [Show full text]
  • Interview with Paul B. Maccready
    PAUL B. MACCREADY (1925 - 2007) INTERVIEWED BY SARA LIPPINCOTT February – March 2003 ARCHIVES CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California Subject area Engineering, aeronautics Abstract An interview in three sessions with Paul B. MacCready, Caltech graduate (MS physics, 1948; PhD aeronautics, 1952) and inventor and entrepreneur who became internationally known in 1977 as the “father of human-powered flight.” Conducted by Sara Lippincott, the oral history covers MacCready’s scientific and entrepreneurial career, including biographical details. MacCready discusses his family life, early education and aeronautical interests in New Haven, CT. During his youth he progressed from the construction of model airplanes to the flying of motor-propelled aircraft and gliders. MacCready recounts his soaring competitions along with his education at Yale in the 1940s; he continues by describing his graduate work at Caltech from 1947 to 1952 and his high altitude soaring in the Sierras and Europe; he relates this to his interest in weather modification and his entrepreneurial work in cloud seeding. In 1971 MacCready founded AeroVironment with his associates Peter Lissaman and Ivar Tombach; he discusses his early clients and research. Beginning in the mid-1970s MacCready began work on the celebrated Gossamer aircraft series; the interview includes discussion concerning the advent of the Gossamer Condor in 1976-1977 and the flight of the Gossamer Albatross across the English Channel in 1979. The interview also includes his continued interest in http://resolver.caltech.edu/CaltechOH:OH_MacCready_P human-powered flight and environmental issues, as well as unmanned solar- powered flight. Administrative information Access The interview is unrestricted. Copyright Copyright has been assigned to the California Institute of Technology © 2006, 2007.
    [Show full text]
  • May 1983 Issue of Soaring Magazine
    Cambridge Introduces The New M KIV NA V Used by winners at the: 15M French Nationals U.S. 15M Nationals U.S. Open Nationals British Open Nationals Cambridge is pleased to announce the Check These Features: MKIV NAV, the latest addition to the successful M KIV System. Digital Final Glide Computer with • "During Glide" update capability The MKIV NAV, by utilizing the latest Micro­ • Wind Computation capability computer and LCD technology, combines in • Distance-to-go Readout a single package a Speed Director, a • Altitude required Readout 4-Function Audio, a digital Averager, and an • Thermalling during final glide capability advanced, digital Final Glide Computer. Speed Director with The MKIV NAV is designed to operate with the MKIV Variometer. It will also function • Own LCD "bar-graph" display with a Standard Cambridge Variometer. • No effect on Variometer • No CRUISE/CLIMB switching The MKIV NAV is the single largest invest­ ment made by Cambridge in state-of-the-art Digital 20 second Averager with own Readout technology and represents our commitment Relative Variometer option to keeping the U.S. in the forefront of soar­ ing instrumentation. 4·Function Audio Altitude Compensation Cambridge Aero Instruments, Inc. Microcomputer and Custom LCD technology 300 Sweetwater Ave. Bedford, MA 01730 Single, compact package, fits 80mm (31/8") Tel. (617) 275·0889; TWX# 710·326·7588 opening Mastercharge and Visa accepted BUSINESS. MEMBER G !TORGLIDING The JOURNAL of the SOARING SOCIETYof AMERICA Volume 47 • Number 5 • May 1983 6 THE 1983 SSA INTERNATIONAL The Soaring Society of America is a nonprofit SOARING CONVENTION organization of enthusiasts who seek to foster and promote all phases of gliding and soaring on a national and international basis.
    [Show full text]
  • Soaring Magazine Index for 1978/1978 Organized by Subject
    Soaring Magazine Index for 1978/1978 organized by subject The contents have all been re-entered by hand, so there are going to be typos and confusion between author and subject, etc... Please send along any corrections and suggestions for improvement. Aerodynamics F.G. Irving, Sigma development to resume, January, page 12 Stan Hall, Understanding structural load' factors, Homebuilders' Hall, January, page 43 Hannu Korhonen, More facts about ¯aps, March, page 5 John McMasters and J.D. McLean, A New Challenge in Human-powered Flight, June, page 16 Flight Tests R. Johnson, A Flight Test Evaluation of the AS-W 20, May, page 21 R. Johnson, A ¯ight test evaluation of the AS-W 20, November, page 26 R. Johnson, A Flight Test Evaluation of the LS-3, November, page 26 Tailless Gliders Robert T. Jones and Bijan Davari, Comparative longitudinal stability of ultralight tailless gliders, January, page 32 Af®liates, Chapters, and Clubs Shelley Hoose, Accent on clubs, January, page 36 Shelley Hoose, Winch or not?, February, page 41 S. Hoose, Bolivian Club Soaring, April, page 43 Charles Shaw, The 1-26 Association, July, page 30 Shelley Hoose, Starting a club, July, page 38 J. Nowak, Barnstorming club makes money, August, page 2 Shelley Hoose, A Motorglider Club?, August, page 52 Shelley Hoose, October, page 46 Shelley Hoose, An Australian soaring club, November, page 46 Competitions Local George Moffat, Needed: weekend contest ¯ying. Soaring to Win, November, page 42 National Soaring Museum NSM News, April, page 14 L. English, Museum News, July, page 8 S. Hoose, National Soaring Museum Support, August, page 53 NSM Building Opens on Harris Hill, November, page 7 Doug Lamont, The National Soaring Museum dedication, December, page 28 National Soaring Museums Chet Decker, NSM gets Albatross, July, page 11 Airplanes Piper DG-100, September, page 9 American Eaglet George Worthington, Getting acquainted with the American Eaglet, March, page 10 Awards Kim McEligot, Kolstad Scholarship Winner, January, page 14 J.
    [Show full text]
  • Helios Prototype Commercialization Near by Jay Levine That’S Some of the Promise of the Helios Prototype
    Special Helios Prototype Edition News May 8, 2002 Volume 44 Issue 2 Dryden Flight Research Center, Edwards, California May 8, 2002 ED01 0230-3 NASA Photo by Carla Thomas The Helios Prototype Aircraft begins a northerly climb over Ni’ihau Island, Hawaii. Conquer the Night ■ Fresh off a record flight last summer, the project seeks to post another record in 2003 Helios Prototype commercialization near By Jay Levine That’s some of the promise of the Helios Prototype. The By Jay Levine X-Press Editor aircraft is intended to be a long-duration, high-altitude bird X-Press Editor As NASA looks at ways to develop technology for transfer that can loiter in the upper atmosphere above 50,000 feet The Helios Prototype set an altitude to the commercial sector, the Helios Prototype could prove to – well above normal air traffic and most importantly above record at 96,863 feet and made a run as be a model. NASA has sought to eliminate some of the risks to most of the weather, Del Frate said. a candidate for one of aviation’s greatest assist in the development of technology that could have nearly It’s clear a mature and validated Helios could have a prizes, the Collier Trophy. unlimited potential, said John Del Frate, solar powered aircraft number of benefits for “any mission requiring an eye in the So what does a project team do for an project manager. sky,” he said. encore? That’s what the Helios Prototype In addition to its uses for science, the Helios Prototype Helios could be an asset for crop management; keep tabs Team began to answer even before the also is seen as a potential way to watch enemies and assist in on environmental changes; monitor fisheries, coral reefs, and record flight – to again demonstrate new fire fighting, emergency services and disaster analysis.
    [Show full text]
  • Soaring Magazine Index for 1980 Organized by Subject
    Soaring Magazine Index for 1980 organized by subject The contents have all been re-entered by hand, so there are going to be typos and confusion between author and subject, etc... Please send along any corrections and suggestions for improvement. Aerodynamics Jack Wilson, Higher Aspect Ratio Tails for Lower Drag?, February, page 4 Higher Aspect Ratio Tails for Lower Drag? (response), February, page 4 H. Gunter Helwig, CAPGLIDE and the RP-1, February, page 22 Richard H. Johnson, Performance^Improvements Through Airfoil Shape Correction, Part I, March, page 23 John McMasters, Experimental Advanced Concepts in Variable Geometry Sailplanes, April, page 26 Al Backstrom, Horten X, Midget and Submidget Sailplanes, June, page 16 John McMasters, Advanced Concepts in Variable Geometry Sailplanes, Part III, June, page 34 Jerry Gibbs, The Golden Glider, July, page 30 Debugger for High-Performance Sailplanes, August, page 8 Jerry Gibbs, The Golden Years of the Golden Glider, December, page 33 Design S. Hall, A Design Critique of Woodstock I, January, page 18 Charles Kerestesi, How I Designed and Built the MG-1, April, page 22 John McMasters, Advanced Concepts in Variable Geometry Sailplanes, Part II, May, page 12 Simple Innovations for Improved Wing Ef®ciency, July, page 5 Peter Myers, Sailplane Designers: Please Protect Us from Lightning Strikes, August, page 3 SSA Homebuilder Class Sailplane Project/ A Call for Design Class Sailplanes, August, page 11 John McMasters, Those Who Have Imagination Without Learning Have Wings but No Feet, October, page 32 Flight Tests Paul MacCready, Jr., NASA Flight Testing Gossamer Albatross, February, page 15 R. Johnson, A Flight test evaluation of the LS-3A, February, page 34 Niels Taarnhoj, FTE's Using Comparison Vehicles, April, page 2 FTE's Using Comparison Vehicle, April, page 2 Dick Johnson, On Flight Testing Techniques, April, page 2 Wolf Lemke, Flight Tests - LS-3, LS-3A, LS-3/17, May, page 3 R.
    [Show full text]
  • 1109 Transcript
    "Flying Free " SHOW1109 Airdate: April 10, 2001 TEASE IS IT A BIRD? THE ETERNAL WING EYES IN THE SKY TAKING TO THE AIR FLAPPING FLIERS WALKALONG GLIDER TEASE ALAN ALDA My eyes are about to take to the air while the rest of me stays firmly on the ground. I'm very nervous. PAUL MACCREADY That makes two of us. ALAN ALDA (NARRATION) We're joining a legendary engineer inspired by nature. PAUL MACCREADY That bird looks like it was having fun. ALAN ALDA (NARRATION) A quarter century after he built the first human powered plane, Paul MacCready's creations are still revolutionary… and are themselves inspiring a new generation of flying machines… including a plane that may one day fly on Mars. ALAN ALDA I'm Alan Alda. Join me as Scientific American Frontiers enjoys the pleasures of Flying Free. back to top IS IT A BIRD? ALAN ALDA (NARRATION) We're here to do some bird watching -- once we spot the bird. BOB HOEY It's hanging underneath the fuselage. It's black. You'll see it when it gets airborne. ALAN ALDA Oh, I see it, yeah. ALAN ALDA (NARRATION) The bird is actually a glider, built by this man, Bob Hoey. Watching with me is Paul MacCready, who's been encouraging Bob in his quest to design a glider that can soar as well as a real bird. To MacCready's delight, Bob seems to have done it. PAUL MACCREADY That's a real bird. ALAN ALDA It really does look real, you're right. ALAN ALDA (NARRATION) Paul MacCready has been watching birds for most of his 75 years.
    [Show full text]
  • By Paul Maccready
    Alan Cocconi (left. BS 1980) and project manager Alec Brooks (PhD 1981) calibrate the angle-ofauack vane on the swing· wing development model of the pterodactyl. Below - the ha/fsize. lateral-control development model is pulled into the air by ground-based winch. The auxUiary tail is dropped away after release from the lOw line. The small bump on the creature's back houses an emergency parachute - just in case. by Paul MacCready OME 65 MILLION YEARS AGO, a gigantic pterodactyl S- a flying reptile - lived in the region now called Big Bend National Park in west Texas. By remarkable good fortune, a few of its fossilized bones, which provide clues to its size and appearance, have survived and been found. These clues suggest that the creature, designated Queizaicoalilis norlhropi, had a wingspan of II meters (36 feet) - the size of a four-person airplane. It is the largest nat­ ural flier known. In late 1983 I realized that there had been recent advances in the aerodynamic theory of oscillating airfoils, in the theory and practice of stability and control, in robotics, mechan- ;' . isms, sensors and servos, and in composite structural materials and techniques - advances that meant that perhaps now a flying replica of QlIelzalcoalllis norlhrop; would be feasible. So we decided to try it. A primary reason for mounting the project was to give people the chance to experience the awesome grandeur of this natural creation in a manner that could never be matched by looking at a static display or even an ani- mated film. A zoo or nature park lets one 18 ENGINEERING & SCIENCE I NOVEMBER 1985 The Great Pterodacty1 Project observe modern living creatures; a natural were found.
    [Show full text]
  • SIERRA WAVE PROJECT REVISITED 50 Years Later
    SIERRA WAVE PROJECT REVISITED 50 Years Later BY VANDA GRUBISIC AND JOHN M. LEWIS Though an important predecessor of modern field experiments, the findings of this 1950s investigation have remained largely out of scientific limelight n the early twentieth century, the sport of manned plished in the lee of the Sierra Nevada. This experi- balloon racing merged with the science of meteo- ment, funded by the Air Force, made extensive use rology to explore the circulation around mid- of the sailplane, another flying platform whose move- latitude weather systems (Meisinger 1924; Lewis ment is in large part dictated by the air currents. The 1995). The information gained was meager, but the experiment was called the Sierra Wave Project, and consequences grave—the death of two aeronauts, its two phases took place in 1951-52 and 1955. The LeRoy Meisinger and James Neeley. Their balloon focus of the experiment was the now well-known was struck by lightning in a nighttime thunderstorm "Sierra Wave" and hazards posed to civilian and mili- over central Illinois in 1924 (Lewis and Moore 1995). tary aviation by such strong mountain-generated dis- After this event, the U.S. Weather Bureau halted turbances. The great achievements in the exploration studies that involved manned balloons. The justifi- of the Sierra Wave in the 1951-52 phase, in which cation for the use of the free balloon was its natural only sailplanes were used, was continued in 1955 with tendency to move as an air parcel and thereby afford the addition of engine-powered aircraft to extend in- a Lagrangian view of the phenomenon.
    [Show full text]
  • Soaring Magazine Index for 1980 to 1989/1980To1989 Organized by Subject
    Soaring Magazine Index for 1980 to 1989/1980to1989 organized by subject The contents have all been re-entered by hand, so thereare going to be typos and confusion between author and subject, etc... Please send along any corrections and suggestions for improvement. AD’s ATechnical Bulletin on the LS-4 and 4a,February,1984, page 8 An AD On ’Chutes,June, 1984, page 8 An AD On Grob G-102’s,July,1984, page 8 An Emergency AD on PIKs,October,1984, page 9 An AD on AS-W 19’s,November,1984, page 11 An AD on AS-W 15’s,December,1984, page 12 George Thelen, An AD on Language,February,1985, page 8 George Thelen, An AD on Air Filters,March, 1985, page 13 George Thelen, An AD on LS-4s,April, 1985, page 8 George Thelen, Towplane BrakeAD,April, 1985, page 9 George Thelen, AD’sand TechBulletins,June, 1985, page 12 An AD on Slingsby T53B’s,September,1985, page 115 George Thelen, TwoGrob109 AD’s,December,1985, page 4 Emergency AD on Libelles,January,1986, page 17 ACentrair AD,March, 1986, page 9 An AD on GROB G-103’s,September,1986, page 8 George Thelen, An AD on G-109B Motorgliders,September,1986, page 28 Towplane Owners; An AD on Cessna 150’s,September,1986, page 28 George Thelen, An AD on GROB G-103 AirbrakeSystems,October,1986, page 8 ATowplane AD,October,1986, page 8 Airworthiness Alert, Bellanca Aircraft,January,1987, page 13 An AD on LS-6’s,February,1987, page 10 Schweizer Release AD,May,1987, page 7 Moreonthe Schweizer Release,August, 1987, page 7 German AD Issued, Ventus A, A/166.,October,1987, page 10 Schempp-Hirth MiniNimbus Technical Note,October,1987, page 10 Grob Control Linkage Failures,October,1987, page 11 Advertising Emergency Airworthiness Directive,GrobG-103 and G-103A,February,1988, page 8 Aerobatics William B.
    [Show full text]