Some aircraft use a fueldraulic system to power some pumps and/or actuators. I guess the best way to model such is to pretend it is electrical, as electrical systems are the most generic and can act as stand-ins for anything?
A fueldraulic fuel pump is a pump that pumps fuel and is powered hydraulically with the hydraulic fluid actually being the same fuel, but using separate tubing obviously, from a separate pump on the engine,
I guess the way to model it is to pretend it is electric. Model the pump pressurising the fueldraulic line as an alternator providing power to a separate bus, and model the fueldraulic fuel pump as an electric fuel pump powered by that bus, right?
If there are cockpit instruments displaying the pressure of such a fueldraulic system, you just display it in the appropriate pressure unit (pounds per square inch, typically) instead of as the voltage you model it as.
Why not just model a regular hydraulic system?
Does it use up fuel or something? If it just returns the fuel back to the tank when it’s finished, the plane isn’t going to notice it’s missing for a little bit and it might as well just be a normal hydraulic system.
What’s the difference in operation that you’re trying to model?
Can there be multiple hydraulic systems?
This aircraft naturally has a normal hydraulic system with hydraulic oil as the hydraulic fluid, too, in addition to the fueldraulic one. In fact, multiple normal hydraulic systems. (As anything more complicated than a single-engine GA aircraft tends to have. As far as I know, MSFS doesn’t currently directly support modelling of such either. See Detailed hydraulic system coming? )
The SDK documentation talks about only “the” hydraulic system. And I can’t find anything in the cfg files that would allow you to define several. In the future the sim will no doubt have multiple hydraulic systems that are defined in a similar fashion as the electrical system with its an arbitrary number of buses and circuits or the fuel system with an arbitrary number of tanks, lines, valves and pumps.
I am looking into the FlyByWire aircraft to see how they handle the multiple hydraulic systems. But that source code (at GitHub - flybywiresim/aircraft: The A32NX & A380X Project are community driven open source projects to create a free airbus aircraft in Microsoft Flight Simulator that is as close to reality as possible.) is a couple of orders of magnitude more complicated than any other aircraft I have looked at, so it requires quite some effort to get an understanding of. But it seems that they simulate their hydraulic systems purely using simvars handled in JS and WASM, etc, not using an electrical system to stand in for the “extra” hydraulic systems.
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To answer your last message, the FBW hydraulics are physically simulated inside wasm module in rust code. All MSFS hydraulics are purely deactivated and we do our own things like the real aircraft
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