In times when Microsoft Flight Simulator 2020 brings an ultra-realistic experience to the home of aviation enthusiasts, in the past the power of simulation and Flight Simulator was infinitely more limited.
Although primitive, this was a necessary device in the pilot training process and also in the creation and standardization of various systems and procedures that today seem natural to us. In this post, we’ll show you a little bit about the old flight simulators.
What is a Flight Simulator?
The flight simulator is the means by which pilots learn all the necessary procedure for piloting modern airplanes, without having to leave the ground or put their instruments, the device and themselves at risk.
When the pilot is in the cockpit of a simulator of this type, he “pilots” an exact replica of the controls and instruments of a real airplane , with a detailed projection of the area that “flies over” in front of him.
During the training exercise, the pilot controls the simulator exactly as he would in a real device, finding virtually all possible flight situations, including unforeseen events, such as storms, fogs, air turbulence and defects in the engine or the device system. The pilot is not restricted to visual interpretation: the fuselage of the simulator is mounted on a hydraulic suspension or, in larger systems, suspended in a kind of frame, in order to provide the same variations of movement that the pilot would have in a real airplane.
View of the control panel in a Lockheed L-1011 TriStar simulator , showing the approach of the track projected on a flat screen. The color film makes the scene even more real (see the old simulation types below).
Engine noise and other sounds produced by the device are also faithfully reproduced, so that the realism is complete. The system is completely computer-controlled – what at the time was a high-speed digital system.
Flight simulators are usually used to adapt crews, that is, to train entire teams in the operation of types of airplanes they have never worked with before. In the 1980s, training was completed in just 3 or 4 hours of flight on real devices, with the remaining 80% of training carried out in simulators.
Part of a closed-circuit color TV screen display system: model of the ground and crane for transporting the camera (see more about the main old simulation methods below).
The fuselages of the simulators are built exactly within the fuselage specifications of the real devices, with greater structural rigidity, so that the assembly can be mounted on the suspension frame. Most of the cockpit equipment that covers the fuselage is made up of real parts, obtained from the manufacturers.
Os controles de voo, manches, manetes, pedestal e todos os outros dispositivos que necessitam de esforço para serem movidos estão montados em uma armação que faz parte da base da fuselagem. Proporcionam uma simulação exata quanto à manipulação de controles, tanto constante quanto variada. Como num aparelho de verdade, as alavancas do manche necessitam de uma força de impulso inicial para serem postas em movimento, e de fricção subsequente, conforme vão sendo movimentadas. Além disso, os controles de voo têm uma característica de variação de carga muito real, de acordo com a velocidade do avião que está sendo simulado. Macacos hidráulicos possibilitam esses efeitos.
Simulator used to train the pilots of Tristar, an old trimotor compared to the MD-11. The white shelter has a screen viewing system and the control cabin, mounted on a base that rests on six movement axes.
The instructor has a control point at the rear of the cockpit. From there, he establishes the flight conditions, selecting them from a list of pre-programmed training exercises, being able to constantly monitor the program through a screen. The instructor can also record and replay parts of a training exercise, check the entire flight or demonstrate, through the simulator, how an experienced pilot managed to face a given situation. Instead of using direct communication between the instructor and the student, radio assistance can be simulated for flight survey, course selection, landings and recorded messages from control towers and stations located on land, so that the flight simulation looks more real.
Flight simulators based on digital computers
Diagram of the complete simulation installation, with a six-axis movement system. The part of the fuselage is suspended from the base by hydraulic actuators that produce the effects of movement. The actuators are operated by the flight movement control unit, which in turn is subordinate to the computer. The visual effects were transmitted by a TV camera that scanned the model at the end of the installation, projecting images on a screen located in front of the fuselage unit.
Old flight simulators already used digital computers to handle the huge amount of information that has to be stored and made available instantly when needed. These computers are devices that operate at extremely high speeds and that can perform, in real time, the mathematical calculations necessary for the flight to appear real.
The data needed for the device is converted into computer programs, usually perforated on paper tape and then loaded into the computer’s memory (yes, my friends, no digital files at the time). It is necessary to convert the analog signals to digital form and vice versa, which is done by the equipment interface.
Any action by the flight crew, such as the positioning of the altimeter, is a physical event that will generate an analog signal, later converted into a digital signal, so that the computer can process it.
The processing result has to be converted to an analog signal, which will be used in order to activate the appropriate instruments of the flight panel. These conversions are done almost simultaneously, to guarantee realism, which is why solid-state interface units, capable of performing twenty conversions per second, are used.
Cockpit of an old flight simulator compared to a current flight simulator.
The human body is extremely sensitive to changes in direction and speed, and it is essential to give the pilot a sense of movement in the simulator in order to make his training more complete. This result is obtained by adapting the simulation cabin to a system that generates movements, which reproduces all the effects felt within a flight unit. Each of these effects results from a series of different hydraulic jacks that move the cab. The most modern systems of the time provided three types of rotation and three types of displacement.
Rotational movements consist of vertical tilt, side tilt and yaw from side to side; the displacements are acceleration (forward and backward movement), jumping (up and down) and sliding (lateral sliding). Due to the weight and dimensions of control cabins, added to the moving platform on which the cabin and the display system are mounted, are used mechanically boosting aids and powerful servo-mechanisms capable of lifting over 40 metric tons.
Three-dimensional model flight simulator
There were usually two main types of visualization systems in use, and a third, whose importance was still growing. The most popular was the closed-circuit color television system, in which the camera visualized the three-dimensional model of a landscape, through an optical probe that goes through it, in order to simulate the flight of an airplane over it, in response to signals emitted by the computer.
Flight simulator by audiovisual reproduction
The second system, in order of importance, uses colored films taken from above, reproducing special routes. Advanced projection techniques allow the image to be distorted in order to simulate movement around the recorded route line, as well as a variation in “speed”. Both systems can be used to simulate night and day flights.
Computer flight simulator
The third system, then known as Computer Generated Image (IGC), continuously changed the model of the scene, stored in the computer, in order to correspond to the simulated position, as well as the theoretical altitude and speed of the device, as they change . The image was shown to the pilot through a cathode ray tube viewfinder (same TV screen system). At the beginning of the use of this technology, there was a limitation and the only IGC systems manufactured for commercial use visualize night scenes.
The flight simulator at home
It is impressive how technology has advanced and what was once still in its infancy today we can count on the comfort of our homes. The quality of the simulation has advanced a lot and today a game that can be purchased by anyone has the quality of a flight simulator hundreds of times superior to the first models, which trained thousands of pilots for the sky.
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Post automatically translated from: Simulador de Voo antigo: como funcionava?