A flight simulator is a training device designed to reproduce aircraft flight conditions and operating environments. A typical system consists of six main components: the motion system, visual system, control loading system, computer system, cockpit system, and sound system. These components exchange data in real time to simulate aircraft movement, cockpit control feedback, and external flight conditions, allowing pilots to conduct flight training on the ground.
Flight simulators differ in hardware configuration, motion performance, visual quality, and computing capabilities according to their qualification level and intended use. The complete system design must be based on the aircraft model being simulated and the relevant training requirements.
Motion System
The motion system reproduces aircraft movement and acceleration during flight, providing corresponding physical motion cues to the pilot. High-level flight simulators commonly use a six-degree-of-freedom (6-DOF) motion platform to simulate pitch, roll, yaw, heave, sway, and surge.
The main components include:
Servo actuators: Electric or hydraulic servo actuators drive the motion platform. They adjust its position and orientation according to outputs from the flight dynamics model.
Motion platform: Supports the simulated cockpit and associated equipment. Multiple actuators work together to reproduce the motion sensations associated with different flight conditions.
Motion control system: Calculates motion commands according to aircraft flight conditions and motion cueing algorithms, coordinating the operation of individual actuators.
Some high-end motion platforms have a single-axis travel of up to ±1 meter and can achieve acceleration levels of 0.7g. These values depend on the platform structure and equipment design and are not universal requirements for all flight simulators.
Visual System
The visual system reproduces the external environment seen by pilots during flight, including airports, runways, terrain, buildings, clouds, and other aircraft. Multi-channel projection or LED display technology is commonly used to provide a continuous external visual scene.
The main technical parameters include:
Display technology: Multi-channel projection systems may provide a field of view such as 200° × 40°. LED displays can also be used to construct an immersive visual environment around the cockpit.
Image resolution: Some systems use 4K to 8K resolution per channel to improve the display of distant objects and airport details.
Pixel pitch: LED display systems use different pixel pitches according to installation distance and display requirements. Some configurations achieve a pixel pitch of ≤0.3 mm.
Refresh rate: Common design specifications include ≥60Hz, while some high-performance systems use 120Hz to improve the display of dynamic scenes.
Visual response and latency: The visual system must remain properly synchronized with the aircraft motion model, instrument displays, and motion platform to prevent noticeable delays in visual feedback.
These specifications for resolution, field of view, pixel pitch, and refresh rate depend on the simulator configuration. They should not be treated as universal standards for all civil aviation or military simulators.
Control Loading System
The control loading system reproduces the forces experienced when operating real aircraft flight controls. It provides pilots with control feedback similar to that of the simulated aircraft.
The system generally includes:
Flight controls: Servo loading mechanisms simulate the resistance of control sticks, control yokes, and rudder pedals. The reference force ranges listed in the original material are 20 to 50 kg for fighter aircraft and 10 to 30 kg for passenger aircraft. Actual values must be determined from the control system data of the specific aircraft model, and the force units must be clearly defined in engineering documentation.
Throttle controls: Mechanical components and damping mechanisms reproduce the operating feel of the throttle lever at different positions.
Landing gear and braking controls: These simulate the resistance and feedback characteristics of the corresponding controls, including changes in brake pedal resistance.
Computer System
The computer system is the central processing and control unit of a flight simulator. It handles flight dynamics calculations, system state updates, visual scene generation, and data communication between hardware components.
Its main elements include:
Computing architecture: A distributed real-time computing network is commonly used to assign flight modeling, visual generation, instrument display, and motion control tasks to the appropriate computing units.
Flight dynamics model: Calculates aircraft responses according to aerodynamic characteristics, engine performance, flight conditions, and pilot control inputs. The original reference specifies a calculation frequency above 400Hz. The actual requirement depends on the system architecture and simulation accuracy.
Scene and environmental database: Contains global terrain, airport, weather, and other flight environment data used to generate flight scenes and simulate environmental conditions.
Cockpit System
The cockpit system reproduces the layout of the actual aircraft cockpit and provides the pilot with operating controls, instrument displays, and control interfaces. In high-level full flight simulators, the cockpit is generally replicated according to the dimensions and configuration of the corresponding aircraft.
The main components include:
Avionics displays: Simulate the display content and operating logic of avionics equipment such as the Electronic Flight Instrument System (EFIS) and Engine Indicating and Crew Alerting System (EICAS).
Control panels: Include physical buttons, knobs, switches, and touchscreens arranged according to the actual cockpit layout. Their operation should match the corresponding aircraft controls.
Environmental and motion cueing equipment: Depending on the simulator configuration, vibration and acceleration cueing devices may be incorporated to reproduce physical sensations associated with certain flight conditions.
Sound System
The sound system reproduces the various sounds generated during aircraft operation and provides auditory feedback to the pilot. Sound output is adjusted according to flight conditions, engine operating parameters, and control inputs.
The main sound elements include:
Engine sounds: Reproduce changes in engine sound characteristics according to thrust and operating conditions. The original reference gives a frequency range of 50 to 5000Hz.
Aerodynamic sounds: Simulate airflow noise during flight, as well as the sounds associated with landing gear and flap extension and retraction.
Warning and alert sounds: Generate warning tones, notification sounds, and system status feedback according to the simulated aircraft's avionics and alert logic.
Flight Simulator Qualification Levels and Performance Requirements
Civil aviation full flight simulators are classified into four qualification levels: A, B, C, and D. Level D is the highest level. Each level has different qualification requirements for cockpit configuration, flight models, motion systems, visual systems, and sound systems.
According to China's Civil Aviation Regulations CCAR-60 and the Civil Aviation Administration of China document AC-60-FS-2019-006, Aircraft Full Flight Simulator Qualification Performance Standards, Level D simulators must meet specific response-time requirements for their motion, instrument, and visual systems. The motion and instrument systems must respond within 100 ms after the aircraft begins to respond, while the visual system must respond within 120 ms.
Level D qualification applies to the performance of the complete flight simulator. Individual components do not receive separate Level D certification. Parameters such as motion platform travel, acceleration, angular error, visual resolution, and refresh rate must be evaluated according to the specific equipment design and applicable test requirements.
