Takeoff

Flight simulators range from games to airline operations, and generally, you cannot (or you are not permitted to) modify the software. Often, the code is proprietary and not accessible, or the acquisition of data used in the simulator is very costly, and the developers of these simulators are understandably protective of their software. However, for a class of simulator known as an engineering flight simulator (EFS) – used by aircraft manufacturers, avionics companies, research organizations, and universities to develop and evaluate aircraft designs and aircraft systems – it is essential to have access to the source code to modify the simulator for a range of studies.

Flight simulators have two important characteristics. First, the accuracy of the simulation (known as fidelity) should ensure that the performance and dynamics of the simulator closely matches the aircraft it simulates. For many flight simulator games, the models are simplified, reducing the fidelity to a level unacceptable in engineering applications. Second, the software must respond in real time to inputs and solve all the underlying equations at a sufficient rate (known as the frame rate), so that the perceived motion is smooth and continuous, without any noticeable lag. If the computations in simulation software are complex, the frame rate may not be sustained, and delays (latency), which further reduce fidelity, are apparent. To ameliorate this situation, a high-performance computer with a state-of-the-art graphics card may be needed to achieve the required frame rate.

Having developed real-time software for flight simulators at the universities of Southampton, Cranfield, and Sheffield; Queen Mary University (London); and the University of Newcastle (Australia), I evaluated the capabilities of the Raspberry Pi (RPi) computer with Linux to provide an acceptable EFS. Details of the software for this EFS are described in a recent textbook [1]. The software referred to in this article is open source and can be downloaded from the Wiley Student Companion Site [2]. The existing simulator software, which was developed for PCs and mostly written in C, ran under Linux and, for compatibility with Linux, also ran under the MSYS2 programming environment on Windows. The software for the aircraft displays was originally written in legacy OpenGL but has been rewritten for OpenGL v4 for the RPi to exploit the power of the Broadcom graphics processing unit (GPU), increasing the rendering rate of the graphics for the displays by a factor of more than 10. The performance of the RPi has enabled the PCs to be replaced with off-the-shelf RPi computers.

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