Link Trainer
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The term Link Trainer is commonly used to refer to a series of flight simulators produced between the early 1930's and early 1950's by Edwin Albert Link, based on technology he pioneered in 1929. These simulators became famous during World War II, when they were used as a key pilot training aid by almost every combatant nation.
Although the Link Company[1] continues to make aerospace simulators, these use very different technology to the original Links, and fall outside the general usage of the term.
The original Link Trainer was created in 1929 out of the need for a safe way to teach new pilots how to fly by Instrument Flight Rules. It was created by former organ builder Link, who used his knowledge of pumps, valves and bellows to create a flight simulator that responded to the pilot's controls and gave an accurate reading on the included instruments.
More than 500,000 US pilots were trained on Link simulators[1], as were pilots of nations as diverse as Australia, Canada, Germany, Great Britain, Japan and the USSR.
The Link Flight Trainer has been designated as A Historic Mechanical Engineering Landmark by the American Society of Mechanical Engineers. [2]
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[edit] Origins
Link had developed a passion for flying in his boyhood years, but was not able to afford the high cost of flying. So, upon leaving school in 1927 he started developing a simulator, an exercise which took him 18 months.
His first pilot trainer, which debuted in 1929, resembled a toy airplane from the outside, with short wooden wings and fuselage mounted on a universal joint. Organ bellows from the Link organ factory, driven by an electric pump, made the trainer pitch and roll as the pilot worked the controls.
Link's first military sales came as a result of the Air Mail Scandal, when the Army Air Corps took over carriage of US Air Mail. Twelve pilots were killed in a 78 day period, due to their unfamiliarity with Instrument Flying Conditions. The large scale loss of life prompted the Air Corps to look at a number of solutions, including Link's pilot trainer.
The Air Corps was given a stark demonstration of the potential of instrument training, when Link flew in to a meeting in conditions of fog that the Air Corps evaluation team regarded as unflyable. As a result, the Air Corps ordered the first six pilot trainers at $3,500 each.
The company expanded rapidly, and during World War II the ANT-18 Basic Instrument Trainer, known to tens of thousands of fledging pilots as the Blue Box (although it was painted in colours other than blue in other countries), was standard equipment at every air training school in the United States and Allied nations. In fact, during the war years Link produced over 10,000 Blue Boxes, turning one out every 45 minutes [3]
[edit] Link Trainer Models
Several models of Link Trainers were sold in a period raning from 1934 through to the late 1950's. These trainers kept pace with the increased instrumentation and flight dynamics of aircraft of their period, but retained the electrical and pneumatic design fundamentals pioneered in the first Link.
[edit] Pilot Trainer
The Pilot Trainer was Link's first model, and was an evolution of his 1929 prototype.
[edit] ANT-18
The second and most prolific version of the Link Trainer was the ANT-18 (Army Navy Trainer model 18), which was in its turn a slightly enhanced version of the model C3. This model was also produced in Canada for the RAF with a somewhat modified instrument panel, where its model designation was D2[4]. It was used by many countries for pilot training before and during the second World War,
The ANT-18 featured movement through all three axes, effectively simulated all flight instruments, and modelled common conditions such as pre-stall buffet, overspeed of the retractable undercarriage, and spinning. It was fitted with a removable opaque canopy, which could be used to simulate blind flying, and was particularly useful for instrument and navigation training.
Many ANT-18 simulators survive around the world today. The USA and Australia are hotspots for survivors.
[edit] ANT-18 design and construction
The ANT-18 consists of two main components.
The first major component is the trainer itself. The trainer consists of a wooden box approximateing the shape of a cockpit and forward fuselage section,which is connected via a universal joint to a base. Inside the cockpit is a single pilot's seat, primary and secondary aircraft controls, and a full suite of flight instruments. The base contains several complicated sets of air-driven bellows to simulate movement, an air compressor which both drives the bellows and provides input to a number of aircraft instruments, and a device known as a Telegon Oscillator, which controls the remaining instruments.
The second major component is an external instructor's station, which consists of a large map table, a repeated display of the main flight instruments, and a moving marker known as a 'crab'. The crab moves across the glass surface of the map table, plotting the pilot's track. The pilot and instructor can communicate with each other via headphones and microphones.
The ANT-18 has three main sets of bellows. One set of four bellows (one under each corner of the cockpit) controls movement in the pitch and roll planes. A very complicated set of bellows at the front of the cockpit controls movement in the yaw plane. A third set simulates vibration such as stall buffet.
Both the trainer and the instructor's station are powered from standard 110VAC/240VAC power outlets via a transformer, with the bulk of internal wiring being low voltage. Simulator logic is all analog and is based around vacuum tubes.
[edit] Survivors
Many link trainers survive around the world.
[edit] Australia
At least twenty two ANT-18 trainers survive in Australia, in various states of repair.[5]. A number of these are in museums, but the majority are in the custody of the Australian Air Force Cadets, who were given them in the 1950's by the Royal Australian Air Force (RAAF).They were maintained until 1975 by the RAAF, and as a result many are still in relatively good condition, being either fully or partially operational. The number of operational ANT-18s has been boosted in recent years by the restoration of several machines.
[edit] Great Britain
At least three Link Trainers are known to exist in Britain. Known survivors are located in the Brooklands museum, the Welford Museum and at 1349 Woking Squadron of the Air Training Corps.
[edit] United States
[edit] See also
[edit] External links
- The Link Company (now known as L-3 Communications)
- The Link Trainer
- Edwin Link Bio
- Link Trainer History
[edit] Notes
- ^ American Society of Mechanical Engineers
- ^ http://files.asme.org/ASMEORG/Communities/History/Landmarks/5585.pdf
- ^ http://www.link.com/history.html.
- ^ http://home.wanadoo.nl/hjaspers000/, Paper to Royal Aeronautical Society Conference, May 2004 by Henrik Jaspers
- ^ ADF Serials, A13 Link Trainer
