ASME International

The Link Flight TrainerA Historic Mechanical Engineering Landmark

Roberson Museum and Science Center, Binghamton, New York

June 10, 2000

Sept. 29, 1931E. A. LINK, JR

1,825,462COMBINATION TRAINING DEVICE FOR STUDENT

AVIATORS AND ENTERTAINMENT APPARATUSFiled March 12, 1930 4 Sheets – Sheet 1

2 Figure 1: Original drawing from Edwin Link’s patent application

Historical Significance of the Work

The Link Trainer is a significantcontributor to the development ofaviation. The Link Trainer provided ameans to train pilots in realistic conditionswithout sacrificing their safety.

Prior to the invention of the LinkTrainer, a pilot learned how to fly byinstruction from another pilot. From1903 to 1917, pilot skills were passedfrom pilot to student. Learning to flywas expensive, time consuming, anddangerous. America’s entry into WorldWar I produced a large number of two-seat flight trainer planes. The mostfamous of these, the “Jenny,” wasproduced near Binghamton by theCurtiss Company in Hammondsport,New York. After World War I, thesetrainers were sold as surplus and wereused in air shows, races, and foramusement rides. Those willing totrain others, and those who hadsufficient time and money to affordlessons, still did pilot training on anindividual basis.

It took several years for Ed Link toobtain his pilot’s license. When hereceived his pilot’s license in 1927, hebegan to think about better ways tolearn how to fly. Using his experiencesfrom flying and working in his father’spiano and organ company, he puttogether a flight trainer. A patentapplication filed March 12, 1930, wasgranted September 29, 1931.

The trainer was based on the vacuumtechnology used in automatic musicalinstruments of the 1920s. In fact, theearliest trainer sat on a series of organbellows, which would inflate or deflateto various heights to cause the trainerto bank, climb, and dive. In 1930, EdLink organized the Link Flying Schoolin Binghamton, New York. The trainerallowed him to reduce the cost offlying lessons by providing a way forthe student pilots to learn some flyingskills on the ground.

In 1929 instrument flying wasintroduced, and by 1933 Ed Link had

upgraded his trainer so that it could beused for instrument training. Interestin the flight trainer grew slowly; in fact,it was more popular as a carnival ridethan a practical trainer in its early days.

The first significant interest for useof the trainer for instrument flighttraining occurred in 1934. Earlier thatyear the U.S. Army Air Corps wasordered to take over airmail service inresponse to mail fraud from privatecontractors. However, there were anumber of highly publicized crashes asa result of pilots not being able to flyon instruments during bad weather ornight flying. These accidents were costlyboth in the loss of human life and theloss of aircraft. The Army becameinterested in the Link Trainer andordered six trainers to improve themail pilots’ skills.

The Link Trainer came intowidespread use during World War IIwhen over 10,000 “blue box” trainerswere used to improve safety and shortentraining time for over 500,000 pilots. Thetrainers were used as a step precedingactual flight training and as an opportunityfor experienced pilots to sharpen their skills.

The legacy of the Link Trainer isvisible today, with flight simulatorsbeing an integral part of pilot training.In recent years, Link simulators havebeen used in many historic applicationsincluding the training of the Apolloastronauts for the moon landing andthe training of space shuttle pilots.

Figure 2: Instructors carefully watch the

progress of a pilot using the Link Trainer

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Contribution of the Work to the Region,State, Nation, World, and the Professionof Mechanical Engineering

The development of the Link Trainer affected the entire world. It has madethe field of aviation safer and has saved the lives of many pilots and airlinepassengers. The numerous awards that Edwin Link received are evidence of thecontribution of the Link Trainer. The Link Trainer also advanced the field ofmechanical engineering. It was primarily a mechanical engineering device thattranslated physical movement of the control devices to pneumatic signals, whichin turn moved the trainer’s control surfaces and caused the trainer to move as anactual aircraft would.

Figure 3: An advertisement promising to improve both a pilot’s instrument flying skills and radio navigation techniques (from the 1940s)

SKY TRAILS LINK TRAINER

are faithfullyand accurately

traced on a mapor chart by theAutomatic Recorderon the Instuctor’s

Desk

be attained

Perfection inInstrumentFlying andRadio NavigationTechnique can

quicker, saterand moreeconomicallyin the LINKINSTRUMENTFLYING TRAINER

Every AviationCadet receivesinstruction int h e LINK TR A I N E R

DEVELOPED AND MANUFACTURED BYL I N K A V I A T I O N D E V I C E S , I n c .

Significant Dates in theDevelopment of theLink Trainer & Simulators

Figure 4: Model of the Lunar Excursion Module, 1964

The Link Flight Trainer was developed by Edwin A. Link after getting hispilot’s license in 1927. The trainer allowed pilots to learn or improve flying skillswithout leaving the ground. Upgrades to the trainer emphasized flying by instrumentrather than visual observation, supporting Link’s belief that flying in the futurewould not be limited to good weather and daylight only.

The development of the Link Flight Trainer was a worldwide contribution. It wasamong the first mechanical devices used to simulate actual processes. The legacyof the Link Flight Trainer continues today, with simulators being used for a widerange of training activities, including commercial, military and space flight.

Link developed electronic training devices

more suited to new, high-performance

aircraft.

1929:Initial patent application submitted April 14

for the “pilot maker” flight trainer.

1930:Link Flying School used trainer to reduce

costs and improve safety.

1930 – 1931:Patent application filed March 12, 1930.

Patent granted to Ed Link September 29, 1931.

1 9 3 4:

U.S. Army Air Corps ordered six Link Flight

Trainers to train mail delivery pilots.

1941 – 1945:Over 10,000 “blue box” trainers used to

train more than 500,000 pilots.

1960s:Link developed simulators for the space

program including the Apollo mission for

moon landing.

Present:Flight simulators now form an integral part

of pilots’ training.

Following World War II:

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Figure 5:

Trainer Fuselage

Interior with

Octagon and Base

1. Rudder Pedal2. Fluorescent Panel Light3. Pilot’s Instrument Panel4. Control Column and Wheel5. Turn Indicator Regulator Bellows6. Flap Control, Landing Gear, and

Propeller Pitch Control Panel7. Fluorescent Panel Light8. Fuselage Control Box9. Microphone and Radio Head Set10. Moonbeam Spotlight11. Operator’s Peephole12. Simulator, Rudder13. Baffle Plate14. Remote Instrument Transmitter Panel15. Spin Trip Bellows and Assembly16. Main Air Transfer Manifold

17. Rudder Valve18. Rough Air Generator19. Air-Speed Damping Tank20. Icing Valve Signal Lamp21. Conductor Elbow22. Spin Valve23. Air-Speed and Manifold Pressure

Regulator Bellows24. Aileron Valve25. Throttle26. Climb-Dive Tank27. Ventilating Fan28. Moonbeam Spotlight29. Simulated Gyro Flexible Shaft30. Simulator, Elevator31. Simulator, Aileron32. Interconnector Box

33. Climb-Dive Valve34. Belt Tightener35. Turning Motor36. Fuselage Stop37. Banking Bellows, Left38. Rudder Bar39. Stall Valve40. Vacuum Turbine41. Automatic Radio Compass Take-Off42. Collector Rings and Brushes43. Wind Drift Mechanism44. Elevator Valve45. Telegon Oscillator46. Base Junction Box

Technical Description

Twith a realistic replication of actual

The Link Flight Trainer consists of

he Link Trainer provided a pilot

flying. This was done by providing a

a scaled-down fuselage that is mounted

responsive movement in the trainerwhen the pilot operated the trainer’s

on a universal joint and control base.

controls. The basic trainer offered the

The trainer is designed so that the pilot

pilot a control column, control wheel,two foot pedals, and various flight and

can simulate banking, pitching, and

navigation instruments. The trainersits on four pneumatic bellows, whichare located on a cross frame.

turning. The flight trainer is designed sothat responses to movement of thecontrol stick or pedals will result in afluid movement of the trainer, similarto that which would be experienced inactual flight.

Control of the flight trainer isprovided by four bellows mounted on

The control system relies on four

the end positions of a rotating cross-

valves. The rudder valve consists of two

arm. Clockwise or counterclockwiseturning of the cross-arm platform is

pieces, a fixed bottom and rotating

accomplished by an electric motor,which uses a belt drive connected to

upper section. As the control wheel is

the cross-arm. The motor operates ona vacuum signal that is generated inresponse to operation of the control

turned clockwise or counterclockwise,

stick and foot pedals.

vacuum will shift accordingly to drivethe turning motor in the correctdirection. Similarly, movement of theupper half of the aileron valve controlsbanking. Alternate bellows on theright and left side of the trainer will

then expand and contract as requiredin response to the pilot’s movement ofthe wheel and cause the trainer tobank to the right or left.

Two other valves, a turn tighteningvalve and an elevator valve, work tobring movements of the controlsurfaces into a smooth response. Forexample, a banking maneuver will alsocause the turntable to rotate.

The Link Trainer also provided fora pilot’s effectiveness in instrumentflying, which could be gauged by havingthe pilot follow a predetermined set ofdirections to reach a destination. Thecover of the trainer would be closed sothat the pilot had no visual reference ofwhere he was going. The pilot’s pathwould be traced out on a map as heproceeded, and the results would becompared against the objective todetermine if the pilot was capable ofinstrument flying.

The Roberson Museum and Science Center’sLink C-3 Trainer

The Roberson Museum and ScienceCenter’s Link C-3 Trainer was movedto the museum in 1973 and restoredby retired Link employees who hadworked on “blue boxes” during theiremployment. Initially it was made fullyoperational and used for classes by theCivil Air Patrol. In 1992 it was overhauledand moved to its current location inthe exhibition, Edwin A. Link and theAir Age. The equipment, which includesboth the trainer and the accompanyinginstructor’s desk, is the centerpiece of arecreated World War II era classroom.

Ongoing maintenance is provided byincome from a restricted endowment,the expertise of former Link workers,

and consultation with technicalstaff in contemporarysimulation companies.

The Roberson LinkTrainer’s serial number indicatesthat it originally was built as aC-3 model; however, later itwas upgraded with partsappropriate to an ANTmodel, a World War II erarefinement. Recent changesinclude replacement of hose withmodern tubing, but otherwise partsare originals or exact replications. Thetrainer is available for viewing by thepublic, daily, year-round, except formajor national holidays.

Figure 6: World War II era classroom with

Link Trainer at Roberson Museum and

Science Center

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Edwin A. Link, The Inventor

Figure 7: Inventor, Edwin A. Link

The life of Edwin A. Link spannedmost of the twentieth century during aperiod of explosive technological progress.

Ed Link was not merely a witness;he was a mover and a creator, for hehad one of the restless, inventive mindsthat could perceive a problem or anopportunity and find a practical solution.

He began as a technician in hisfather’s automatic piano and organfactory, but while his hands were busywith automatic musical instruments,his heart was in the sky. It was, in fact,his experience with the difficulty, danger,and expense of early flight training thatinspired him to find a way to train pilotson the ground. Working in the basementof his father’s factory, he built a trainerthat could simulate the motions of anairplane as the student manipulated thecontrols. Realizing that pilots could notalways expect to fly on sunny days, headded more instruments to his ground-based trainer and used it to train pilotsto fly “under the hood,” preparing themfor flying in cloudy or foggy weather.

At first the stubby-winged, one-person trainer was successful only as acoin-operated carnival ride. Graduallyit began to be used in flight schools,and in 1934 the Army Air Corpspurchased six trainers, primarily fortraining the military pilots who at thetime were carrying mail for the postalservice. As the Second World Warapproached, Link trainers were builtfor governments around the world.At peak wartime production, the Linkfactories in Binghamton and Canada

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were producing 80 trainers per week, In 1960 Link had designed and built aand the now famous “blue box” was Submersible Decompression Chamberpreparing men from all backgrounds (SDC) to allow divers to return to thefor service as pilots. The company also ship’s deck quickly from the ocean depthsbuilt a celestial navigation trainer for and then to decompress slowly on board.training bomber crews and navigators, As his interest shifted from archaeologyand a bubble sextant for making to ocean science, Link developednavigational sightings aboard aircraft. equipment to allow man to work and

Beginning in the 1950s, Ed Link live under water for extended periodsbegan to phase himself out of the of time. He designed a Submersibleaerospace business and into a career in Portable Inflatable Dwelling (SPID) inunderwater exploration. Flight simulation, 1964, and the mini-sub Perry-Linkhowever, has continued to be a critical Deep Diver in 1967. Deep Diver waspart of training for all types of aircraft, the first submersible with a lockoutfrom helicopters to the space shuttle. system that could send out a diver toWhen Neil Armstrong maneuvered work on the ocean floor. Link thenthe Apollo lunar lander down to the designed a second lockout submersible,surface of the moon, flying a craft that the Johnson-Sea-Link, which introducedno one had ever flown before in a place the use of acrylic and aluminum forno human had ever been, he said, deep-sea vessels and had removable“Everything is A-OK. It throttles down components. He helped design thebetter than the simulator.” Cabled Observation and Rescue Device

Ed Link and his wife, Marion, had (CORD), one of the first successfulbecome interested in underwater remotely operated vehicles, that allows theexploration. They began with simple,recreational treasure hunting, divingoff their sailboat, the Blue Heron. Soon,however, the lure of the unexploredocean made them dissatisfied withtheir sailboat and its equipment. Astreasure hunting gave way to seriousunderwater archaeology, they outfitteda large twin diesel-powered boat as aseagoing laboratory and named itR/V Sea Diver.

By 1962 the Links had conductedexcavations in the waters off Jamaica,Mexico, Israel, Greece, and Sicily.

crew on a surface ship to use televisioncameras and lights for underwaterreconnaissance. Its claws and cutterscan free a trapped submersible. Late inhis life, Ed Link became interested inantique steam engines, alternativesources of energy, and finding newuses for energy from the wind and sun.Edwin A. Link died September 7,1981. His legacy, however, is still withus. During the Persian Gulf war ofearly 1991, superior technology andthe excellent training of Americanpilots, all trained in simulators, helpedbring the war to a quick close. At theHarbor Branch OceanographicInstitution, the research vessel EdwinLink regularly carries a crew andsubmersible out to sea to study howman can best use and preserve theoceans. Progress in flight simulation,marine science, and ocean engineeringwill always have roots in the life andwork of Edwin A. Link.

Figure 8: Edwin Link in a Link Trainer 9

ASME International

The History and Heritage Programof ASME International

The History and Heritage Landmarks Program of ASME International(the American Society of Mechanical Engineers) began in 1971. To implementand achieve its goals, ASME formed a History and Heritage Committee initiallycomposed of mechanical engineers, historians of technology, and the curator(now emeritus) of mechanical engineering at the Smithsonian Institution,Washington, DC. The History and Heritage Committee provides a publicservice by examining, noting, recording, and acknowledging mechanicalengineering achievements of particular significance. This Committee is partof ASME’s Council on Public Affairs and Board on Public Information. Forfurther information, please contact Public Information at ASME International,Three Park Avenue, New York, NY 10016-5990, 1-212-591-7740.

DesignationSince the History and Heritage Program began in 1971, 209 landmarks have

been designated as historic mechanical engineering landmarks, heritage collections,or heritage sites. Each represents a progressive step in the evolution of mechanicalengineering and its significance to society in general. Site designations representan event or development of clear historic importance to mechanical engineers.Collections mark the contributions of a number of objects with special significanceto the historical development of mechanical engineering.

The Landmarks Program illuminates our technological heritage and encouragesthe preservation of the physical remains of historically important works. It providesan annotated roster for engineers, students, educators, historians, and travelers.It helps establish persistent reminders of where we have been and where we aregoing along the divergent paths of discovery.

The Link Flight Trainer 1930

The trainer, designed by Edwin A. Link,

provided a pilot with a realistic

replication of actual flying. It sat on

four pneumatic bellows that converted

the pilot’s movements of the controls

to pneumatic signals, that in turn

rotated a series of mechanical linkages

causing the trainer to turn, pitch, and

bank. In simulating actual flight

characteristics, the trainer allowed

pilots to learn or improve their flying

skills without leaving the ground. From

its inception through today’s advanced

versions, the Link Trainer has helped

develop the flying skills of hundreds of

thousands of pilots and significantly

improved flying safety.

Figure 9: Text from ASME landmark plaque The 125,000 member ASME International is a worldwide engineering societyfocused on technical, educational, and research issues. ASME conducts one ofthe world’s largest Publishing operations, holds some 30 technical conferencesand 200 professional development courses each year, and sets many industrialand manufacturing standards.

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ASME InternationalJohn R. Parker, P.E., PresidentRaymond L. Jackson, Vice President,

Region IIIVirginia W. Ross,

Region III History and HeritageHarry Armen, Senior Vice President,

Public AffairsVictoria A. Rockwell, Vice President,

Public InformationDavid L. Belden, P.E., Executive Director

The ASME History andHeritage Committee

ASME Southern Tier SectionSuresh T. Gulati, P.E., Chair

R. Michael Hunt, P.E., History & Heritage Chair Gary Miller, Vice ChairRobert M. Vogel, Secretary Barr L. Fetherolf, SecretaryWilliam J. Adams, Jr., P.E. David R. Treacy, TreasurerWilliam DeFotis Thomas M. Sine, P.E., History & HeritagePaul J. Torpey, Past President Joseph De Angelo, P.E., NominatorHerman H. Viegas, P.E.Diane Kaylor, Staff Liaison

Bibliography1. Memorial Tribute Edwin A. Link 1904-1981, National Academy of

Engineering of the United States of America, February, 19822. The Scribner Encyclopedia of American Lives, Volume One, 19983. A Biographical Sketch of Edwin A. Link, Florida Institute of Technology

Catalogue, 19914. The Edwin A. Link Collection: A Register of the Link Archival Collection at

the Roberson Museum and Science Center, 1991

Photo/Illustration ReferencesCover Photograph: Link Trainer with desk contact unit, 1940sFigure 1: Original drawing from Edwin Link’s patent application, filed 1930Figure 2: Photograph of Link Trainer in a classroom setting, 1940sFigure 3: Advertisement for Link Flight Trainer, 1940sFigure 4: Photograph of model for the Lunar Excursion Module, 1964Figure 5: Diagram of the Link Flight Trainer fuselage interior with octagon and

base with reference list of parts; Overhaul Instructions for Instrument FlyingTrainer, Type AN-2550-1, February 10, 1945

Figure 6: Photograph of World War II era classroom with Link Trainer at theRoberson Museum and Science Center, Binghamton, New York

Figure 7: Photograph of Edwin A. Link, 1950sFigure 8: Photograph of Edwin A. Link in a Link Trainer, 1940sFigure 9: Text from ASME landmark plaque

Patent ReferencePatent Application No. 1,825,462Filed: March 12, 1930Granted: September 29, 1931

AcknowledgmentsNomination of the Link Flight

Trainer was made by the Southern TierChapter of ASME and the RobersonMuseum and Science Center.

This landmark brochure waswritten by Joseph De Angelo, P.E. andedited by Laura St. George and JamesMoody of the Roberson staff.

The publication was designed byElizabeth Garufi of Elizabeth AnneDesign, Binghamton, New York.

Appreciation is extended toMarilyn Link for providing historicalinformation and to the Link Foundationfor funding.

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ASME InternationalHistory and Heritage CommitteeAmerican Society of Mechanical Engineers

Three Park Avenue, New York, NY 10016-5990

Roberson Museum & Science Center The Link FoundationRoberson Museum and Science Center is a regional,

multidisciplinary museum and science center. Robersonencompasses the main campus in Binghamton, New York,four historic buildings, and the Kopernik Education Centerin Vestal, New York. Roberson offers unique museum andeducational resources to the Southern Tier of upstate NewYork and Northeast Pennsylvania.

The Link Flight Trainer located at the Roberson Museumand Science Center is the best example for designation as anASME Historic Engineering Landmark. While there areseveral other displays of the Link Flight Trainer, the LinkTrainer at Roberson is located in the City where the trainerwas developed. The Roberson Museum and Science Centeralso contains the Edwin A. Link Collection. This collectionincludes more than 6,000 items, with a significant amountof information on the development of the Link Flight Trainer.The Link Trainer is located in a recreated World War II trainerclassroom environment in the exhibition, Edwin A. Link andthe Air Age. The Roberson Museum and Science Center isopen to the public on a daily basis, which provides anexcellent opportunity to view the exhibit and learn moreabout Ed Link and the Link Flight Trainer.

Roberson Memorial, Inc.David Chesebrough, Executive DirectorRoberson Museum and Science Center30 Front StreetBinghamton, NY 13905607-772-0660

The Link Foundation is a New York Charitable Trustestablished in 1953 through the generosity of Edwin A. Linkand Marion C. Link. The Link Foundation supports researchin the fields of simulation, energy and ocean engineeringand instrumentation through the awarding of fellowshipsand grants. In addition, the Link Foundation supportsinstitutions like Roberson Museum and Science Center andBinghamton University, both of which were particularfavorites of the Links during their lifetime.

To year 2000, grants totaling over $5,600,000 havebeen awarded to universities, colleges and other nonprofitorganizations.

© May 2000 Roberson Museum and Science Center