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I've always wondered, what sort of computing power is needed to keep modern commercial and military planes in the air?

There are many systems of a modern commercial plane (e.g an Airbus A350), that would need to be automated and controlled by computer, one example that springs to mind is autopilot, another is flight instruments.

Similarly I'm assuming that there'd be many systems (e.g fly-by-wire) that need to be controlled by computer in a modern military jet (e.g F-22 Raptor).

What sort of computing power is needed to run commercial planes and military jets, and how do they compare to each other, and how does their computing power compare to the computing power of modern commercial CPU's? (Could my 2nd-gen Intel i7 CPU, with the appropriate hardware to make it into a PC, hypothetically be able to control all the automated systems on a modern commercial plane or military jet?)

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    $\begingroup$ Could your single i7 (4 core) processor run all the flight systems on board a modern aircraft, no. Just like your car, there are dozens or more processors running highly optimized, specialized code. There isn't a way to run all that on a single system, even if it is significantly faster than what is used in aircraft today. $\endgroup$ – Ron Beyer Nov 29 '17 at 5:11
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    $\begingroup$ While the i7 has a power of less than 100 GFLOPS (probably 70 for a 4 GHz i7), a powerful video adapter has a power of 500 GFLOPS. So the power in a desktop computer is not really in the CPU, but in the GPU (as the size of the fans tells us). $\endgroup$ – mins Nov 29 '17 at 7:24
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    $\begingroup$ One big difference is your average CPU is build to do anything in the average while the GPU is build to do one kind of task very well also tge CPU must control the GPU, Disks and others devices $\endgroup$ – jean Nov 29 '17 at 9:38
  • $\begingroup$ @mins Do avionics systems perform enough floating-point calculations that GFLOPS (billions of floating point operations per second) would be an appropriate measure of performance? I can absolutely see some use for floating-point in avionics, but I can also see plenty of applications where fixed-point or integer arithmetic would seem to make more sense. $\endgroup$ – a CVn Nov 29 '17 at 10:40
  • $\begingroup$ @mins Sure, the bottom line is we are comparing apples with oranges and OP apples with peanuts =) $\endgroup$ – jean Nov 29 '17 at 10:56
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For commercial airliners: the computing power is set during development and certification of the type. The A320 was developed in the 1980s and still uses Intel 80186 and Motorola 68020 processors. Your i7 CPU would be able to run rings around anything on board of the average airliner.

But processing capacity is of secondary importance to airliners, safety and redundancy are in the limelight. Any processor capacity that can do the job is good enough, and is only the start of all the aspects that go into certifying an airliner including its systems.

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Military planes are different, in that the requirements are more pressing and the accepted risks are higher. Yes modern fly-by-wire planes use digital systems, however when the F-16 first came out with a fly-by-wire control system, it was a quadruple redundant analog system, with a digital processing requirement of zero. These were upgraded to digital fly-by-wire in the block 40/42 upgrade in the early 90s, so again the fly-by-wire used pretty primitive processors by today's standards.

Generalising, the long development and certification/ready-for-mission time of aircraft systems means that any system on board uses processing power that is behind the latest-to-market specs.

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  • $\begingroup$ Even Military aircraft are pretty primitive by today's standards based on the advancement of electronics technology. I remember when the F-22 rolled out in 1997, LMACO had bragged that the the two Common Integrated Processors (CIP) in the jet had the computational power of four Cray Supercomputers at the time; These days, the average home PC is superior in processing power. $\endgroup$ – Carlo Felicione Nov 29 '17 at 3:45
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    $\begingroup$ @CarloFelicione ...and a lot of the time, we use that home PC to watch videos of kittens. $\endgroup$ – a CVn Nov 29 '17 at 10:41
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Flight code is generally not cleverly designed to be efficient, but rather clear and simple, so an optimization rewrite can save some CPU time. If you only have 1 processor, then you have no redundancy to worry about, no need to log faults or data redording since only one thing that can fail, only I/O needed would be directly from sensors and to controls/displays. Leaves you with only the core functions to process. This slims the processor load down by at least half. Get rid of partitioned OS, TAWS, synthetic vision, controls channel b, assume external sensors and controls never fail and maybe, just maybe, you (not me) could fly on a single multi core i7, for some peiod of time.

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  • $\begingroup$ How is it determined if a processor is fit for used in large civil aircraft? Please don't point me to the respective technical specification, a short overview would be great. $\endgroup$ – user7241 Dec 10 '17 at 8:15
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With a current processor power, Flight Management would be more than possible. The mathematical operations in an automatic flight control system are quite simple (matrix multiplication, some transfer functions, some filters) for a cpu of today’s standards.

The trick would be to have a robust operating system (real time maybe), and to handle the I/O within the time window required for the control.

This answer assumes GPS and INS data are fused in a separate device, and actuator commands are driven through servo actuators.

Especially In military aircraft, and also in commercial aircraft several high frequency filters need to be included into the controller, to decouple it from structural modes. This brings in more computational requirements, but would be easily handled by the processor, as long as the necessary data I/O does not choke the processor.

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