Flight simulator

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For the flight simulator software from Microsoft, see Microsoft Flight Simulator.

Interior cockpit of a modern flight simulator

A flight simulator is a system that tries to replicate, or simulate, the experience of flying an aircraft as closely and realistically as possible. The different types of flight simulator range from video games up to full-size cockpit replicas mounted on hydraulic (or electromechanical) actuators, controlled by state of the art computer technology.

Flight simulators are extensively used by the aviation industry and the military for pilot training, disaster simulation and aircraft development. Engineering flight simulators are also used in the aerospace industry as a platform for such tasks as:

development, testing, and verification of flight hardware (referred to as "stimulation" of flight hardware)
for testing and development of flight software
for developing new cockpit displays for improved crew situational awareness.

1 History
2 Modern simulators
3 Next generation flight simulators
4 Flight simulators at home
- 4.1 Space flight simulators
- 4.2 Homebuilt simulators
5 See also
6 External links

[edit] History

Because powered flight is hazardous to attempt untrained, from the earliest days various schemes were used to enable new pilots to get used to the controls of the plane without actually being airborne. For instance, the Sanders Teacher was a complete aircraft mounted on a universal joint and facing into the wind, able to rotate and tilt freely. Another early flight simulator of about 1910 was built using a section of a barrel mounted on a hoop.

Link trainer

A number of electro-mechanical devices were tried during World War I and thereafter. The best-known was the Link Trainer, which in 1930 just simulated mechanical motions, but was later enhanced to include instruments and was used by a number of countries during World War II and after.

The Celestial Navigation Trainer of 1941 was a massive structure 13.7 m (45 ft) high and capable of accommodating an entire bomber crew learning how to fly night missions. In the 1940s, analog computers were used to solve the equations of flight, resulting in the first electronic simulators.

In 1948, Curtiss-Wright delivered a trainer for the Stratocruiser to Pan American, the first complete simulator owned by an airline. Although there was no motion modelling or visual display, the entire cockpit and instruments worked, and crews found it very effective. Full motion systems came in starting in the late 1950s.

A mock-up terrain visual system of the TL39 simulator

The early full motion systems often simulated ground terrain using an actual model of the terrain, and “flying” a camera over it to mimic the position of the aircraft. The resulting pictures were relayed to the pilots on TV monitors. Naturally rather limited areas of the ground were able to be simulated in this manner, usually just the area around an airport. A similar system was used by the military to simulate bombing raids, etc. The use of digital computers for flight simulation began in the 1960s.

In 1954, General Precision Inc., later part of Singer Corporation, developed a motion simulator which housed a cockpit within a metal framework. It provided 3 degrees of pitch, roll, and yaw, but by 1964 improved, compact versions increased this to 10 degrees. By 1969 airline simulators were developed where hydraulic actuators controlled each axis of motion, and simulators began to be built with six degrees of freedom (roll, pitch, yaw for angular motion and surge, heave and sway for longitudinal, vertical and lateral translation). Starting in 1977, airline simulators began adopting the modern "cab" configuration where computers are placed in the cockpit area, and equipment is accessed via a wraparound catwalk.

Around this time great strides were also made in display technology. In 1972 Singer developed a collimating lens apparatus, using a spherical mirror and beamsplitter, which projected views at optical infinity out the cockpit window. This greatly improved the illusion of flight. However it only offered a field of view of 28 degrees. In 1976 wide field collimated displays (e.g. [1]) were introduced. By the 1980s high-quality collimated displays had become a standard feature of airline simulators.

[edit] Modern simulators

A "Level D" all-electric full flight simulator

Today, there are various categories of flight simulators used for pilot training. These categories range from seemingly simple “system trainers” to six degree of freedom motion simulators. Six degrees of freedom refers to the ability of the simulator to recreate axial moment and rotation on each of the three axes. This gives the pilot the ability to feel pitch, roll, yaw, acceleration, deceleration and heave. There are various minor variations within each of these categories, but they all essentially provide the equivalent training capabilities.

Contrary to popular belief, today's modern flight simulators are not used as much to train pilots on how to fly aircraft as they are to familiarize flight crews in normal and emergency operating procedures. Using simulators, pilots are able to train for situations that they are unable to safely do in actual aircraft. These situations include loss of flight control surfaces, complete engine failures and loss of pressurization. Today’s aircraft are complex computer-based devices and in order to operate them efficiently, pilots must possess a high level of technical as well as piloting skills.

Most regulatory governmental bodies such as the U.S. Federal Aviation Administration (FAA) recognize each category of simulators. These regulatory bodies are also required to certify the performance of these devices. U.S. commercial pilots can only log required training time in simulators certified by the FAA. In order for a simulator to be certified, it must be able to demonstrate that its performance matches that of the airplane that is being simulated. The testing requirements are detailed in test guides referred to as an Approval Test Guide (ATG) or Qualification Test Guide (QTG). Simulators are classified as Level 1-7 flight training devices (FTD) or Level A-D full-flight simulators.

System trainers are used to teach pilots how to properly operate various aircraft systems. They are not normally used for “flight training” or “emergency procedure” training. Once pilots become familiar with system operations, they will transition to cockpit procedures trainers or CPTs. These fixed base devices are exact replicas of the aircraft and are used to train flight crews in normal and emergency procedures. They also duplicate the atmospheric environment in which the aircraft will fly – simulating wind, temperature and turbulence. CPTs will also simulate the various sounds produced by the aircraft such as engine, landing gear and other sounds. Some may also be equipped with visual systems. However, they are not equipped with systems that simulate aircraft motions.

Large Amplitude Multi-mode Aerospace Research Simulator (LAMARS)

A full motion simulator (also known as a full-flight simulator) will duplicate all aspects of the aircraft and its environment, including basic motions of the aircraft. These type of simulators can generate momentary jolts so that the occupants in the simulator must wear seat belts as they do in the real aircraft. As the motion of any simulator is far more restricted than that of a real aircraft, the motion system does not “mimic” the motion and attitude of the aircraft. Instead, it gives so called “motion cues” to the pilot, trying to “deceive” his/her senses and to make the pilot feel flying. In order to do that properly, knowledge of the human sense organs, particularly of the vestibular system, is extensively employed.

Four common manufacturers for simulators are FlightSafety International (USA),CAE Inc. (Canadian),Thales Training & Simulation (French), and Rockwell Collins (USA), who produce civil full flight simulators and military fixed based simulators.

Flight simulators are also extensively used for research in various aerospace subjects, particularly in flight dynamics and man-machine interaction. Both regular and purposely-built research simulators are employed. The latter range from the simplest ones, which resemble video games, to very specific and extremely expensive designs such as LAMARS, installed at Wright-Patterson Air Force Base, Ohio, which features a large scale five degrees of freedom motion system and the visual system with more than 180 degrees field of vision in all directions.

The TL39 3-DoF motion simulator with IOS at MAI University

Most simulators are also equipped with facilities that are used by instructors. These are referred to Instructor Operating Stations (IOS). At the IOS, an instructor can quickly create any normal and abnormal condition in the simulated aircraft or in the simulated external aircraft environment. This can range from engine fires, malfunctioning landing gear, electrical faults, storms, lightning, oncoming aircraft, slippery runways, navigational system failures and countless other problems which the crew need to be familiar with and act upon.

Many newer simulators allow the instructor to control the simulator from the cockpit, either from a console next to the co-pilots seat, or by adjusting certain instruments in particular ways (for example, entering a specific transponder code), allowing them to program basic scenarios using the cockpit interface. This allows the training of a single pilot in aircraft that require a crew of two, allowing the instructor to serve as the second pilot.

In the past full motion flight simulators had been limited to multi-million dollar hydraulic devices used at large training centers such as FlightSafety International. Recent advances in electric motion simulation bases have permitted full motion simulation to be utilized economically for much smaller aircraft including single-engine piston aircraft at training centers such as Flight Level Aviation.

Flight simulators are an essential element in individual pilot as well as flight crew training. They save time, money and lives.

[edit] Next generation flight simulators

High end commercial and military flight simulators incorporate motion bases to provide the most realistic simulation possible. The majority of these simulators rely on the venerable Stewart platform to generate motion. Using hydraulic cylinders, these systems provide reliable motion for many flight training scenarios. However, the Stewart platform has one primary drawback. The drawback is limited pitch, roll, and yaw. Motion bases using Stewart platforms typically max out at less than +/- 35 degrees of pitch or roll. Several companies are performing research and development on advanced motion platforms that will someday provide for increased amounts of pitch, roll, and yaw.

AMST Systemtechnik (Austria) and TNO Human Factors (the Netherlands) are building the Desdemona flight simulation system. This large scale simulator provides unlimited rotation via a gimballed cockpit. The gimbal sub-system is supported by a framework which adds vertical motion. Furthermore, this framework is mounted on a large rotating platform with an adjustable radius. The Desdemona simulator is designed to provide sustainable g-force simulation with unlimited rotational freedom.

Moran Simulation is developing a simulator called the Mimicker. Based upon a patented design, the Mimicker uses a gimballed capsule for unlimited rotation. Vertical motion is provided by a counterweight mechanism integrated into the gimbal framework. Horizontal movement is accomplished by a propelled-pivoting motion base with rotating disc. The motion base is designed to use all available floor space for maximum horizontal motion.

Simulation Kinetics, Inc. is developing a simulator which uses a rotating spherical capsule. The basic concept of this design was first patented during WWII. A more recent example of this design is the Rotational Flight Simulator built and operated during the space race. This simulator capsule measures 3m (10ft) in diameter and weighs 2,903kg (6,400lbs). The Rotational Flight Simulator is now in storage at the USAF Museum of Aerospace Medicine at Brooks Air Force Base. Simulation Kinetics, Inc. is developing a new spherical capsule simulator named the Xenosphere. This new prototype measures slightly under 2.4m (8ft) in diameter and is made of lightweight composites. This new simulator is designed to produce a combination of unlimited rotation with high levels of agility.

[edit] Flight simulators at home

Flight Simulator 2002: a modern PC flight simulator

Crude flight simulators were among the first types of programs to be developed for early personal computers. Bruce Artwick's subLOGIC simulators were well-known for the functionality they managed to get onto 8-bit machines.

A popular type of flight simulator are combat flight simulators, which simulate combat air operations from the pilot and crew's point of view. Combat flight simulation titles are more numerous than civilian flight simulators due to variety of subject matter available and market demand.

Screenshot from FlightGear, a flight simulator available under the GPL.

In the early 2000s, even home entertainment flight simulators had become so realistic that after the events of September 11, 2001, some journalists and experts speculated that the hijackers might have gained enough knowledge to steer a passenger airliner from packages such as Microsoft Flight Simulator. Microsoft, while rebutting such criticisms, delayed the release of the 2002 version of its hallmark simulator to delete the World Trade Center from its New York scenery and even supplied a patch to delete the towers retroactively from earlier versions of the sim.

The advent of flight simulators as home video game entertainment has prompted many users to become "airplane designers" for these systems. As such, they may create both military or commercial airline airplanes, and they may even use names of real life airlines, as long as they don't make profits out of their designs. Many other home flight simulator users create their personal, virtual version of their favorite real world airline, and so virtual airlines such as Virtual Delta, Mexicana Virtual, Virtual Aeroflot, Viasa Virtual and so on can be found online. These modifications to a simulation (colloquially known as 'mods') generally add much to a simulation and often grant a significantly expanded playing experience with new situations and content. In some cases, a simulation is taken much further in regards to its features than was intended, or even envisioned by its original developers. Falcon 4.0 is an excellent example of such modification; whole new warzones were added along with the ability to fly hundreds of different aircraft, as opposed to the original single flyable airframe.

In addition to actually flying in the game, many users have discovered "Online air traffic". This is when virtual pilots and virtual ATCs play together in real time to simulate a true air traffic experience. There are several networks, the most popular ones being VATSIM and IVAO.

Screenshot from FlightGear, a flight simulator available under the GPL.

Popular simulators for home computers include:

Civilian:
- Flight Unlimited series of PC simulators
- FlightGear, an accurate GPL flight simulator with full world scenery and many aircraft models
- Fly!
- Microsoft Flight Simulator series, one of the most widely-used civilian flight simulators
- X-Plane, a highly accurate multi-platform flight simulator and the only one to be certified by the FAA for training purposes
- Aerowinx Precision Simulator, a full Boeing 747-400 CBT (Computer Based Training), used by some airlines in the training of their pilots on the 747-400

Combat:
- Aces High, combat flight simulator and massively multiplayer online game for the PC
- Fighter Ace, combat flight simulator and massively multiplayer online game for the PC
- Falcon 4.0, an extremely detailed 'study sim' of the F-16 Fighting Falcon.
- Su-27 Flanker (game) contained a realistic and detailed flight model in a less competitive graphics shell on pc.
- IL-2 Sturmovik, one of the leading World War II flight simulators
- Lock On: Modern Air Combat, Jet Combat simulator.
- Combat Flight Simulator WWII Europe Series, Microsoft's first in its series (of 3) of WWII Aircombat
- B-17 Flying Fortress, B-17 Bomber simulator in WWII
- European Air War, a highly rated simulation in the E.T.O. in WWII
- Gunship, a simulator focusing on the AH-64 Apache attack helicopter
- Battle of Britain II: Wings of Victory,a complex simulation of the Battle of Britain

Much rarer but still notable are flight simulators available for various game consoles. The most notable of these were Pilotwings, made available for the Super Nintendo, the sequel Pilotwings 64 for the Nintendo 64 and the Ace Combat series on Playstation 1&2. The very rare Sky Odyssey is yet another example of console flight simulators. Due to the restrictive nature of a game consoles's ability to properly simulate environments in general and the processing limitations of these systems in particular, game console-based flight simulators tend to be simplistic and have a more "arcade"-like feel to them. While generally not as complex as PC based sims, console flight simulators can still be enjoyable to play, however their 'simulation' status is disputed by many in the Flight Simulation Community.

[edit] Space flight simulators

Main article: Space flight simulator

As space is a natural extension of airspace, space flight simulators may be treated as an extension of flight simulators' genre. There is a considerable interdependence between those two kinds of simulators, as some flight simulators feature spacecraft as an extension and the other hand some space flight simulators may feature a pretty realistic atmospheric flight simulation engine.

Popular space flight simulators for home computers include:

Microsoft Space Simulator
Orbiter, a freeware space flight simulator
X-Plane, also includes a Space Shuttle and Mars flight simulators
Space Shuttle Simulator, freeware simulation of the Space Shuttle

[edit] Homebuilt simulators

In recent years, with the advent of cheap yet powerful personal computers, many people have taken to creating homebuilt simulators of a variety of aircraft, ranging from a few panels with a screen on top to full-blown motion simulators, with every switch and gauge reconstructed in fullsize. The author of one such ongoing project, of a Boeing 747, has posted a web site [2] to track the construction of his project. Various online communities exist for builders of such simulators, such as this website for home cockpit builders.

Such homebuilt simulators are generally powered by a software package such as one of the ones shown above.