Ground physics - weird behavior

[Ray Proudfoot 8,976]

10 minutes ago, eslader said:

Respectfully disagree. If someone is complaining about ground handling being wrong and the first video they show is of the Wright Flyer - ground handling for which involved a team of men lifting it onto a rail - they're pretty obviously not being a serious critic of genuine issues.

Any aircraft modelled in MSFS should work reasonably well. If the op feels it doesn’t he’s entitled to bring it to people’s attention. Probably best on the official forum though.

[Claudius_ 326]

Sometimes someone is asking about ground physics on a flight simulator, but yes sometimes something weird is happening on the ground, but this depends on how a certain airplane is implementing it, because we have better airplanes than other from this point of view. Also, when someone is talking about XP12 and the supposed better ground physics, I'd like to see a video just for comparison, because when I tried  to fly the default C172 in the XP12 demo it was a disaster from all aspects. Some default FS20 airplanes like the C172, the TBM930, the Citation, are ready to fly and with a very good flight model without any modding. But the ground physics sometimes need to be improved in FS20, I know that, but it's improving.

Edited November 2, 2023 by Claudius_

[lwt1971 7,419]

Cutting thru all the fluff and despite the comically contrived nature of this thread's OP, here are the facts around ground handling in MSFS:


1) It is a well known problem area that MS/Asobo have also acknowledged at multiple points (both ground handling and the ground<->air transition modelling), and put out interim fixes/enhancements in SU10 to mitigate the issue, with a fuller re-work planned for the future. The new SU10 FM parameters need to be taken advantage of by aircraft developers.. and ones like the Fenix, PMDG, etc already have, and that has lead to tangible improvements at least in my eyes, especially in cross-winds.


2) See this Developer Q&A from May where Seb talks about these new SU10 FM parameters: https://forums.flightsimulator.com/t/live-dev-q-a-may-25th-2022/521293/2
Chat question – What are some improvements that are coming for ground friction and handling? - Timestamp 3

Seb – Four new parameters are coming in Sim Update 10. Two of them are going to give the possibility to eliminate or at least tune, but we decided to cancel it out on our plane where we tested it. Basically, an old feature that we kept from FSX. FSX was canceling out all crosswind below a certain speed. At 50 knots, you had 100% crosswind, and then it was fading out to 10 knots and then it was 0. The problem is, while you take off or land, the crosswind keeps changing. And it’s very unnatural. So this is something where, in the parameters for the plane you can say at what speeds you want this to happen. So on the Cessna 172, we’re testing this, so we basically canceled the effect completely. So you have a 100% crosswind even if you are parked, or if you go very slow. If there is a lot of wind, it can actually spin your plane around, at first. So that’s one of the new parameters.

Seb – And the other one, two parameters are there to allow you to control how sticky your wheels are when they are rolling fast. So when you are already going pretty fast in the takeoff, the sim was considering the wheels to be pretty much on rails as if there were slick tires from a Formula 1 car. Very sticky. And only the weight…so if you pull on the yoke, your plane gets a bit lighter. And the weight goes down, which reduces friction a little bit. But it’s still static. So it means that as long as you don’t push to the side strong enough, you’re still on rails. And so, there’s two parameters that allow you to make it so that the plane drifts off. The wheels are spinning so if you push to the side, it’s going to drift off a little bit, especially with plane tires that are not anything but racing tires. So we tested that with taildraggers. Taildraggers will always be hard to land and takeoff. But it’s a lot more natural and easy with that. So this is something we implemented on the Extra 330 for Sim Update 10. Also, plane makers have examples of how this works, so they can use it, too. We will deploy on more based on feedback. These four parameters are a first step on improving the ground handling. So more stuff will come afterwards. But Sim Update 10 is going to be these four.


3) In an earlier Q&A from March, Seb spoke about the fuller re-work they have in mind around ground handling/physics (see below).. my guess is that re-work will only fully realize in MSFS 2024, but who knows, depending on the scale and type of changes some or all of that could be backported to 2020 too. At least in my case, I'm not going to care much about 2020 after 2024 drops 🙂

https://forums.flightsimulator.com/t/live-dev-q-a-march-2nd-2022/503504
Seb - ... But still, there is a deeper rework we need to do. Basically, it all comes from heavy simplifications that were in the sim 10-15 years ago, which were always assuming that the ground was flat. That’s why you couldn’t have sloped runways or undulated runways. The ground friction model…basically when something’s on the ground and when the brakes are fully engaged, you don’t move at all: The plane sticks to the ground. There’s what one could call infinite friction: There’s no movement at all. This is something we added that didn’t exist at all. And it wasn’t really needed 10 years ago because there were no slopes. When you put a plane on a flat terrain without wind, it’s not going to roll anywhere. But if you put that same system on a slope, it’s going to roll away and not stay there.

There’s also wind. Historically, in the sim, there was a system so that at low speeds, any crosswind was cancelled out. The plane ignores any form of wind, when you’re below, maybe 5-10 feet/second, which is why when you’re stopped on the ground, you go full propeller power and then there’s some propeller effects, so the plane starts going left. And then, all of a sudden, the wind kicks in, and then if you have a strong crosswind, it does this sort of thing which is not realistic. In reality, if I have a plane on the ground, and there’s a strong wind, and I release all brakes, it’s going to start moving: The wind is going to push it. And that currently does not happen. There are changes like that that we want to do. We want to do the ground friction model to make it 100% realistic. Which means that we don’t have to do anything: We don’t have to cancel it out anymore. Everything is going to be realistically simulated from when you stop to when you take off. There’s no such thing as crosswind that comes in over a few knots. I think it’s going to make the rudder a little easier. You’re just fighting one crosswind. It doesn’t change over time unless there’s gusts. Also, it’s going to work better on slopes. This rework is planned for somewhere this year, whenever we have time to go into that. It’s going to be compatible because the parameters are the same. It doesn’t change anything in the way you define or create or make airplanes. It just changes the way all the constraints and forces are sold so that the plane does what it’s supposed to do. All the constraints are the friction, the ground friction, the prop wash, the wind, even the engine, which is slightly shaking the plane. All these things come together. Currently, it’s a little bit better because we worked more in a bug fix development system, where we said, “The plane is sliding on the slope? Let’s fix that.” “The plane is sliding when there’s wind? Let’s fix that” Now we’re in a situation where we need to implement a real system instead of having a block of patches. That’s basically the next step, and that will give us much more realism the precise moment when you rotate.

For example, a wheel is currently simulated as a single point. So, a wheel can resist movement or rolling or sliding when you brake. It does not resist rotation. A wheel can rotate [with a rudder or tiller] without resistance. If you’re in your car and you’re parked, and you turn the steering wheel, if you don’t have power steering, it’s not easy to turn the tire because it’s not a point: It’s a flat surface. It’s a patch on the ground of rubber that you’re moving. The new simulation is going to allow this. This helps with stability when you’re taking off. Currently, the plane is just a tripod of points, and as soon as the nose is up, you feel that it’s already twisting because the wheels are not simulated as patches of rubber. They do not resist rotation enough. These kinds of changes are going to make the moments of takeoff a lot more precise and realistic. Later this year.
 

 

Edited November 2, 2023 by lwt1971

[fsiscool 251]

How is blowing wind many times as fast as the aircraft's takeoff speed showing anything about the ground behvaior? The aircraft crash, what would anybody expect? The wind speed is far outside the envelope for which the correct behaviour just can be assumed.

[flying_carpet 657]

21 hours ago, eslader said:

I also thought OPs testing of ground physics with the Wright Flyer was silly. That thing didn't have ground handling. It launched off a rail and skidded to a stop on sand. Turning wasn't part of the equation.

So, the Wright Flyer was not only the first (motorized) plane, but also the first one "flying" on rails 😁.

On a serious note: what would happen, if it didn't stop on sand, but on concrete? Would it also move forwards with crosswind? That's EXACTLY the purpose of simulators (isn't it?), to simulate things which you usually don't do, due to being too dangerous/difficult/expensive/etc. to do in real life.

 

21 hours ago, eslader said:

The crosswind component on those things is somewhere south of 20kts for a reason, and in 50-60kts many owners would be looking for a hangar to stick it in because they wouldn't trust the tiedowns.

That's EXACTLY the purpose of simulators (isn't it?), to simulate things which you usually don't do, due to being too dangerous/difficult/expensive/etc. to do in real life.

[eslader 1,784]

11 hours ago, Ray Proudfoot said:

Any aircraft modelled in MSFS should work reasonably well. If the op feels it doesn’t he’s entitled to bring it to people’s attention. Probably best on the official forum though.

In fairness, by even old-fashioned standards the aircraft in question didn't work reasonably well either. 😄

 

4 hours ago, flying_carpet said:

So, the Wright Flyer was not only the first (motorized) plane, but also the first one "flying" on rails 😁.

Technically it was off the rails by the time it was flying. 😄

    

Quote

On a serious note: what would happen, if it didn't stop on sand, but on concrete? Would it also move forwards with crosswind? That's EXACTLY the purpose of simulators (isn't it?), to simulate things which you usually don't do, due to being too dangerous/difficult/expensive/etc. to do in real life.

 

 

I wouldn't expect Xplane to simulate the friction coefficient of polished wood on concrete either.

 

[snglecoil 1,828]

4 hours ago, flying_carpet said:

That's EXACTLY the purpose of simulators (isn't it?), to simulate things which you usually don't do, due to being too dangerous/difficult/expensive/etc. to do in real life.

Some people use it to simulate flying exactly as they would in real life, even employing ADM to avoid dangerous/difficult/etc. situations.  Some people painstakingly recreate normal airline operations and avoid irregular operations as a matter of making it as realistic as possible. Some people fly a 747 inverted under the Golden Gate bridge because they can. Some people just want to know what operating a plane/helicopter/glider might be like. Some people like to look at pretty scenery and imagine what it would be like to travel there in real life. Some people want to have their plane try to (virtually) kill them every flight with some random failure. Some people buy fake planes with fake money earned by flying fake people on fake jobs. Some people let a silly computer program spark a life-long love of aviation that leads to a career with their head in/under/around/above the clouds. 

[jcomm 5,939]

On 11/1/2023 at 5:39 PM, flying_carpet said:

Does that mean that they will "cheat" somehow without calculating the behavior?

It's WIP @flying_carpet...

ASOBO was at least (I have to admit as much I am critic of pretty much ALL flightsims I use) were at least BRAVE to revolutionize the trend we were all following in terms of flight simulation, and the base handed to them to start their work from.

I remember early after release having posted at their Support Forum about a long time limitation imposed on roll rate, inherited from the fs9/ fsx times and preventing aircraft like an aerobatic ( Extra, Pitts, Yak... ) a WW2 or modern fighter... from rolling at realistically high roll rates and then stop the rolling almost instantly. Well, in less than 1 month this was "fixed" and since then we can have realistic roll rates.

Ground physics were initially designed based on the "classic" FM but the plans are to bring it to a much more detailed level of accuracy, with wheels and their physical characteristics fine tuned and allowing for much more realistic behaviour. 

This is just one of a myriad of fronts ASOBO is working on, and contrarily to what was preconized by many, it's far from being stagnated or abandoned... and it's actually BY FAR the most dynamic development of a flight simulation game platform I ever used.

What I mean is, just as with any other platform still under development, like P3dv6 which is now my main focus for future developments, XP12, AeroFly FS... we have to learn to be patient, and enjoy what we already have the best we can.

I recall how unrealistic the effects of x-wind still are in XP12, where a slight normal component or variable wind set in the weather parameters can bounce a 738 or an A320, a 777, a 747, wildly... or raise the upwind wing of an airliner during take off... Yes it's kind of the opposite of "on rails", but to the far end where it becomes plagued by lack of accuracy / realism as well...

Let's wait for the still upcoming SUs before the release of MFS 2024, or for MFS 2024 itself which, as much as I can get from what I read, looks promising, to say the least!

Ah! and it's also important to make sure you use the best quality addons, just as in any platform. There are many aircraft available, free and payware for MFS, but I use the game only for playing being an airline pilot in a 737 or, sometimes, in an Airbus (although for that matter P3D and FSLabs are still my preferred, and yes I have used pretty much all of the Airbuses available for XP11 and 12...). 

You should try the PMDG 737s in MFS ! Even the ground physics look so much more convincing that you can more easily wait for upcoming updates to the base ground physics !

 

Edited November 3, 2023 by jcomm

[Epgd 136]

...............You should try the PMDG 737s in MFS ! Even the ground physics look so much more convincing that you can more easily wait for upcoming updates to the base ground physics !

If you say that ground physics is better in pmdg in FS than, for example, in Zibo in xp12... then in my opinion you are very wrong...

[Alpine Scenery 1,609]

I mean even having been in a commercial jet and landed so many times, I can tell the ground physics still need work. Though they also needed work in the other games as well, in different ways. A real plane has a much springier absorption to the downward momentum on the landing, it's like planes in this game are using metal tires. Sure, there is a hard landing in real life many times, but not nearly as many times as this game. You have to grease the landing in some planes to prevent a bounce, not realistic.

 

 

 

Edited November 4, 2023 by Alpine Scenery

[flying_carpet 657]

On 11/2/2023 at 3:58 PM, Claudius_ said:

Sometimes someone is asking about ground physics on a flight simulator, but yes sometimes something weird is happening on the ground, but this depends on how a certain airplane is implementing it, because we have better airplanes than other from this point of view. Also, when someone is talking about XP12 and the supposed better ground physics, I'd like to see a video just for comparison, because when I tried  to fly the default C172 in the XP12 demo it was a disaster from all aspects. Some default FS20 airplanes like the C172, the TBM930, the Citation, are ready to fly and with a very good flight model without any modding. But the ground physics sometimes need to be improved in FS20, I know that, but it's improving.

 

On 11/2/2023 at 4:02 PM, Bobsk8 said:

I have a few hundred hours IRL flying the C 172, and the several times I tried the C 172 in XP, I couldn't believe how unrealistic it felt. 

Could you both be a bit more specific, please? I mean, proving your statements with verifiable facts (e.g. video, data output, ...)?

[flying_carpet 657]

On 11/3/2023 at 8:19 AM, jcomm said:

It's WIP @flying_carpet...

ASOBO was at least (I have to admit as much I am critic of pretty much ALL flightsims I use) were at least BRAVE to revolutionize the trend we were all following in terms of flight simulation, and the base handed to them to start their work from.

I remember early after release having posted at their Support Forum about a long time limitation imposed on roll rate, inherited from the fs9/ fsx times and preventing aircraft like an aerobatic ( Extra, Pitts, Yak... ) a WW2 or modern fighter... from rolling at realistically high roll rates and then stop the rolling almost instantly. Well, in less than 1 month this was "fixed" and since then we can have realistic roll rates.

Ground physics were initially designed based on the "classic" FM but the plans are to bring it to a much more detailed level of accuracy, with wheels and their physical characteristics fine tuned and allowing for much more realistic behaviour. 

This is just one of a myriad of fronts ASOBO is working on, and contrarily to what was preconized by many, it's far from being stagnated or abandoned... and it's actually BY FAR the most dynamic development of a flight simulation game platform I ever used.

What I mean is, just as with any other platform still under development, like P3dv6 which is now my main focus for future developments, XP12, AeroFly FS... we have to learn to be patient, and enjoy what we already have the best we can.

I recall how unrealistic the effects of x-wind still are in XP12, where a slight normal component or variable wind set in the weather parameters can bounce a 738 or an A320, a 777, a 747, wildly... or raise the upwind wing of an airliner during take off... Yes it's kind of the opposite of "on rails", but to the far end where it becomes plagued by lack of accuracy / realism as well...

Let's wait for the still upcoming SUs before the release of MFS 2024, or for MFS 2024 itself which, as much as I can get from what I read, looks promising, to say the least!

Ah! and it's also important to make sure you use the best quality addons, just as in any platform. There are many aircraft available, free and payware for MFS, but I use the game only for playing being an airline pilot in a 737 or, sometimes, in an Airbus (although for that matter P3D and FSLabs are still my preferred, and yes I have used pretty much all of the Airbuses available for XP11 and 12...). 

You should try the PMDG 737s in MFS ! Even the ground physics look so much more convincing that you can more easily wait for upcoming updates to the base ground physics !

 

It might be that Asobo is trying to improve the ground physics. Apart from that, I doubt they will do (much) more for "realistic" flying. They have toned down a lot of things due to user complaints, e.g. icing, turbulences, ... Is there anything known that they want to improve also the water physics?

[jcomm 5,939]

1 hour ago, flying_carpet said:

It might be that Asobo is trying to improve the ground physics. Apart from that, I doubt they will do (much) more for "realistic" flying. They have toned down a lot of things due to user complaints, e.g. icing, turbulences, ... Is there anything known that they want to improve also the water physics?

They're planning to continue their work on the CFD method, fine tunning different aspects, probably for MFS 2024, so I believe we will be able to notice differences for the better in future updates of 202 and almost for sure with the release of 2024.

 

 

[flying_carpet 657]

Actually I only asked for provable FACTS, but what do we get instead? Personal attacks/accusations ... Is it really too much to ask for (provable) FACTS? Thanks for your attention ...

[Rimshot 1,143]

4 minutes ago, flying_carpet said:

Actually I only asked for provable FACTS

Who cares. Play the sim you like and be done with it.