Understanding What Systems the Sim Simulates

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As a person whose life has been steeped in technical knowhow, im curious about the “under the hood” aspects of the sim. As such, I’m trying to understand what aircraft systems are modeled in the simulator.

For instance, is there a base electrical/charging system model that aircraft model builders tap into? Or is every model builder expected to construct an entire electrical system from scratch on their own?

I ask this, because I see different behavior in the electrical systems of similarly equipped aircraft. I’m not talking about nuanced differences, but rather large differences. All you good pilots are looking at the status of your electrical systems, right?!

Examples:
• 152 shows pegged 60A(!) constant charge when running at speed regardless of electrical load and never settles down to near zero once the battery is charged post startup. The Junkers Ju 52 1939 does this, too
• 172 G1000 (with WT NXi) shows what looks like pretty normal behavior, yet with no switchable loads remains at 47A charge and never settles towards zero after prolonged running to reflect a charged battery post-startup state
• Carenado C170B is the oddest. When you first turn on the Master switch, it will show a 10A draw, which persists even after you turn the master switch back off. The ammeter will then jump to zero at idle, but shows no negative draw with all electrical loads on when idling. It will jump to show a positive when above 2000 RPM, but it never settles down to near zero to indicate the battery has been charged.

What is consistent with all of them is a lack of a charged battery state being reflected in the charge rate of the ammeter.

Similarly, I’m constantly pondering the C170B’s Cylinder Head Temperature gauge. Now, I know upon initial release, there was a bug with the aircraft where the gauge was pegged full hot. That isn’t the case now. What is intriguing me is when the aircraft is off, the gauge shows ambient, but when you start the engine and it’s idling it moves towards and remains at 0°. In flight, it never really seems to get very hot (~150°) regardless of what I do with the mixture. As such, is this a system that Carenado have just tapped into and it’s not right or are they feeding the system the wrong values and it’s just reflecting that or did they have to model this themselves and it isn’t right?

How does all this business work? I’m curious about this nerdy macro level technical whatnot. So, yeah, if I was an MSFS sim model builder, what is the deal? Do I “plug in” to a pre-modeled system in the sim or do I have to make it all from scratch?

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I think developers do the best with the information abaiable. I doubt developers have original aircraft and engine blueprints. The available systems diagrams are pretty basic in the POH. Also, the aircraft represent the aeronautical state-of-the-art for the specific production dates. For example, the TBM 930 systems aren’t updated to the TBM 940 or 950. Also, there is a price point for simulation. The systems modeled in consumer flight simulators are not the same as commercial simulators used by airlines.

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Right, but I’m speaking of the background process of it all. Is there a base electrical system that models a battery, electrical draw, a charging system and an ammeter to display its current (pun!) behavior? Do the developers then add switches and electrical loads per the various electrical devices on their model? Or is it all totally up to the developers to model?

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Well yes, there is a baseline electrical system in the game. However, every plane’s specific system is unique in terms of sources and loads, so folks developing a plane have to “wire” the system accordingly. You know, planes have different combinations of batteries, generators, alternators, APUs, and whether they can use a GPU. Some planes have electric flaps and/or landing gear, air conditioning, and all sorts of other things that suck power, while others don’t. So every plane has to be “wired” differently. But they all use the same baseline system, unless the dev wants to code something else up from scratch.

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This is what I expected to be the case.

As such, I have to assume the base sim charging system isn’t programmed to simulate a charged battery’s effect on the charging system, hence all the aircraft showing constant significantly positive ammeter readings.

The odd issues with the C170B seem like, maybe, what Carenado are plugging into this base electrical system are erroneous, which is why it’s behavior is markedly different from the other two examples? Obviously, I can only guess.

The sim fascinates me and attempting to simulate all these real world systems is even further fascinating to me.

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The more hardcore-nerd absolute study-level maxed out system depth an airplane has, the more precious it is.
Because that´s the only way to really learn about planes :wink:

Because when not owning a plane (or having access to one as real PPL in some flight club) one will never know what these more little and more hidden engine and electrical system gauges in a real plane show: How much the amperemeter changes when switching on pitot heat and landing lights, how long does it really take until an aircraft battery is drained when only the gyroscope motor is running and GPS on standy-by, how hot the cylinder head temperature gauge needle climbs when leaning the mixture, and many more interesting technical details.

A flight simulator is about simulating being born from money and owning an airplane - that´s why absolute system depth and system realism is the most important aspect, otherwise the immersion is shattered by unrealistic simpleton arcade stuff never meant to be “life-like”.

But are these sub-systems realistic like oil temperature and cow(l)-flaps open or closed, oil pressure, manifold pressure (changes depending on height or prop RPM lever), amperemeter, cylinder head temperature with cow flaps open and closed, and other details?
In a PMDG plane very likely.

But PMDG unfortunately does not develop anything else than airliners and that´s why we will never get a PMDG Cessna 182RG Turbo, a PMDG Cessna 340, or other true to the core study-level GA planes, and Accu-Sim A2A and also AirFoilLabs which are probebly ultra-realistic in all aspects too both refuse to give us their (almost) REAL Cessna 172 :frowning:

And other planes… I am not so sure but unfortunately I am in no way able to find out what the real airplane would do. Even when watching YouTube startup taxi and take-off videos I cannot read these tiny gauges in the more distant corners of the cockpit to check if they show the same value as my simulated counterpart.

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I’m developing for the G36 Improvement Mod and we are slowly iterating over the default systems. There is no real charging system that I have found to date, we have changed the simulated wattage/amperages that the various instruments, lights etc use.

Currently I have been spending several months trying to simulate the spark plugs and spark fouling in the aircraft.

The new system of using XML & RPN to make mini apps is quite powerful and I think I’d be able to simulate alternator usage as well. The biggest short fall as I’ve found so far is a lack of ability to create the symptoms one would see when an aircraft has an issue e.g. rough running when having spark fouling.

It is very much the wild west of trial and error at the moment but this is very exciting as it creates a lot of new innovation. My personal goal is to do everything ‘in house’ and by that I mean without any external programs etc.

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I love the way you guys think, be it that i might not understand everything of it, especially the programming/wiring side of things.

The majority of users out there, just want to grab a plane and feel like they are in control, whereas the monitoring of the basic instuments is where most of our knowledge stands… the intricacies of the wiring diagrams and the real knowledge about how the aformentioned sparkplugs can give clues to the maintenance of the aircraft is for the real die hards… even though i’d like to see accurate engine temperatures from cold and dark, i too am not as nerdy to really use it to analyse an engine/airframe before flight… but i bet it’d be an awsome learning experience.
(just like i tried a go-around with the Corsair at Course Pitch… which blew the engine and shook me… :wink: but i found out that the course pitch gives such a load on the engine at low altitude that it basically got torn apart by it’s own power… my brain was working overtime trying to think what i did wrong as i floated down, cockpit window full of oil from less than 200 feet just above stall speed! hahaha)
but yeah, i’d love to see a refined engine system to teach eachother how to properly use the propulsionsystem and it’s electricals. (it’d be an eye-opener to anyone wanting to be in the real world flying business too)

Woof ~ Woof & Salute!

Steiny

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Rest assure, you are not the only one !!
I made some comments about the C172 electrical system some months ago, but it did not lead anywhere, so I just Modded my C172 myself and moved on.

One very significant electrical characteristic that is not modeled (at least in the Asobo planes), is the Internal resistance of the battery. The sim simulates a Zero Ohms internal resistance, so the battery terminal voltage does NOT drop with load.

As you turn more thing on, it does simulate the increased current draw, but it does not indicate the battery terminal voltage drop which is also a function of charge (ie Battery internal resistance decreases with charge)

So, why does this matter ?

For example,
IF the battery is not fully charged, some things should work ok, and other things, like the starter, should drop the battery terminal voltage, so that other items can often shut off, landing light dim, etc and eventually, the starter solenoid cannot keep engaged, and you get the classic Click click click of the starter solenoid, when trying to start the engine.

You cannot start the engine, BUT - If you are NOT cranking it, the battery voltage rises high enough that you can use the radio, and call for a Jump start !!

Currently, in the sim, its all or nothing works as the simulated battery “Charge” (incorrectly the battery voltage) decreases.

The frustrating thing is, this is so easy to simulate, if only those designing the electrical l systems, knew enough to realize this very basic functionality, and included it in the sim.

BTW:

152 shows pegged 60A(!) constant charge when running at speed regardless of electrical load and never settles down to near zero once the battery is charged post startup.

This sound like the Starter motor is running continuously, a classic symptom of some Hardware Yokes and their associated controls and or, the C172 ammeter being reversed.

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Whew, I’m not alone in my “flight engineer” mentality.

The thing is, the more I get into aviation as a simmer (it had been a 25 year pause for me until MSFS 2020), the more I crave more realism in the simulation of the aircraft themselves. I want to be “doing it wrong” and suffer the consequences, so I can learn how to do it right.

I had no idea sim aircraft like PMDG’s DC-6 even existed until I bought it. When I got my hands on it, well, wow!

For me, as much as I find it “neat” to have access to so many planes in the base sim (and those in Deluxe/Premium), I’d so much rather have had one or two that were highly detailed systems-wise than so many that aren’t. Quality over quantity, as they say,

The base Cessna 152 is so close in this regard that the small things that aren’t quite right stand out so much to me. I think, “You came this far, why didn’t you just go the whole distance?”

I get the desire for more and more aircraft, in real life none of us would have such access to a plethora of planes, but the less realistic the mass of them are, the less I’m interested in flying them beyond the novelty of experiencing their most basic differences.

The 3rd party improvement mods aren’t available on my Xbox, which is certainly a drag and it’s my hope a system for supporting them will be implemented in the future. I see this in other sim products on Xbox, so it’s certainly possible. This alone could push me further toward flying on my PC more, but the loss of visual fidelity over what I have on the Xbox is hard to overcome in its own way.

Anyhow, it’s good to be amongst like-minded people.

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Quite a number of years ago, I basically asked the same question on Avsim. And someone pointed me to A2A. Getting my first A2A aircraft was almost literally a game changer for me (not quite literally, because P3D is by definition not a game, as you cannot use it for entertainment purposes). Google for reviews of e.g. the A2A Comanche for P3D.

A2A Simulations have yet to release an aircraft for MFS, but many of us who share your mindset, feel that MFS will only be complete for them when this happens. It could well be a year or more away… I don’t think A2A ever compromises on the “it’s done when it’s done” rule, their releases are of exceptional quality, and quality takes time.

I think in the XP world, Hot Start has a similar approach, but I don’t expect them to ever release an aircraft for MFS.

Disclaimer: I’m an A2A fanboi.

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Hmmm, ok, my example is not real to sim, but I have RV. The amp gauge on dash, constantly shows 13.5VDC rate all the time. Yes, I realize that is the output of the alternator on the engine. Mine will never show fully charged when using since I have the inverter stealing DC, changing to AC so the refrigerator works when going down the road. When plugged into shore power (50A=100A total-50A per leg), eventually after several hours of plugged into SP, the charger goes to zero, showing full charge on my panel. However, the “appliances in the RV” are still using some electricity, so incoming amps/use could be 1-49 depending on what is running on that leg.
Simulator is or should be somewhat same, eventually, the battery fully charges, the amp draw/load should go down, but the output from alt/gen should still have some usage, because electrical things are running, i.e., radios/navigation etc.
I actually never gave it much thought, as figured, that is way under the “hood so to speak” and for sure Asobo/developer got that correct. Now another thing to watch and worry over. I would assume we would get warning if alternator fails in flight, and I have that kind of stuff enabled in settings.

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This is an outstanding question, and the answer really gets at how poorly this studio has done at producing a flight simulator.

I’ve said from say one, this is a great VFR general aircraft scenery centric flight sim, and still today it falls short of being a complete flight sim.

No one expects that every system will be fully modelled. But it would be really helpful to know which systems are and are not modeled. And yes, developers do have access to the data.

In the flight simulator that is taboo here, what they do is take the POH (Pilots Operating Handbook) and they modify that, and what specifically isn’t simulated they annotate “not simulated”. That lets the user know there is no sense trying to set this knob, and it isn’t a bug.

Also, no one expects that the base, or “free” aircraft be 100% modeled. This is what 3rd party market is for – if you really want every system fully modeled then you buy a study level aircraft.

This sim studio just doesn’t get it. It’s sad really. Somewhere along the SU trail they made a lot of switches no longer interactable. For example, you used to be able to turn batter power on/off and avionics power on/off in the C172, and you used to be able to adjust the mixture stopper. Now that ability is gone, and no it isn’t because those systems aren’t modelled because in “realistic” mode the mixture needs to be set. But since we can’t interact with the stopper.

If I was product manager, this is where I would start. Taking a full inventory of what does and doesn’t work, then determining what is supposed to work, and get the documentation in order and make sure that everything needed to basically fly the aircraft is working.

Its not good for the users, not good for MS/Asobo, and even not good for the 3rd party market that this mess exists. Because the folks that want the aircraft electrical system to be fully modeled probably would be willing to pay for a product that adds that to the experience.

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As soon as I can I’ll get the Bonanza Improvement Mod onto the XBox :slight_smile:

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Are you sure about this? An ammeter doesn’t show voltage it shows amperage. Are you actually looking at a voltmeter, which will show system voltage as you’ve described.

Two very different gauges presenting very different information.

BTW, very few motor vehicles are equipped with ammeters today. It was the charging system gauge of choice in early automobiles until the sixties when they began being phased out for simple “idiot” lights and/or voltmeters, which are easier to understand.

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See, this is the sort of thing I was hoping for here, but I’m not sure it really is implemented.

Take that 152 running its alternator at a sustained max output rate of 60A. That alternator would be so hot it would, literally, melt the solder in its armature and fling it away due to the centrifugal force whilst spinning. Bye, bye alternator.

I really don’t think these things will happen to us in the skies unless the 3rd party folks have taken the, blessed, effort to implement it.

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I’m really keen to implement a lot of what is being discussed here, if there are any of you who would have a little time to help guide the mods development on that front I’d love to hear from you!

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I’d be happy to spend time working with you in any capacity you need.

I can definitely utilize my PC for testing purposes, as well.

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What gives me hope with this sim is the fact that Asobo have partnered with the good folks at Working Title to develop and implement the Garmin NXi. It’s my understanding they will continue in this vein with the other GPS units and, ultimately, overhaul ATC.

This bodes well for the sim. It means Asobo is open to working with 3rd parties on systems upgrades and, since that is the case, it doesn’t seem out of the realm of reason they would do the same with other 3rd parties taking on realism improvements.

Fingers crossed for the future, for sure!

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Fantastic! I’ll pm you :slight_smile: