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BeamNG.Science

Discussion in 'General Discussion' started by Drivver, Jul 26, 2016.

  1. Drivver

    Drivver
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    Well... I'll not made big introduction, explaination etc. This is topic for science, physics, comparison to real life and overall cool things you tested in BeamNG.Drive .

    If you wanna contribute you have to choose subject i.ex. comparing how safety changed in last 50years, include screenshots (outside, inside), descriptions, some explainations to made it look nice and informative. Comments, feedback and discussions are welcome.

    Example from past:

    Select "Open in new window" and zoom in:

    Subject: centrifugal forces vs measured and actual speed

    While gauge says 321km/h the air speed is 333km/h. Because wheel at 321km/h have height of 673px, and at 0km/h it have 643px. So simply 673 x 100 / 643 and it equals to around 104% of wheel at 0km/h. Then measured speed 321km/h x 1.04 ~ 333km/h. As simple as that.

    BeamNG physics makes it pure. Just like in real life when you drive fast like this your actual speed is higher than showed on gauge, because it's measuring wheel revolutions and it don't make correction for centrifugal forces that makes wheel bigger. Yup whole wheel, rims and mostly tires - while rim is expanding just a little bit that it's almost unnoticeable tires are expanding actually a lot. Enough to made difference as 4% in wheel diameter. When wheel is bigger it obviously makes more distance per revolution. Difference is shown in orange bar. So theoretically saying 1px = 1mm we can go a bit further in explanations. 643 x 3.14 (π) = 2019mm (~2,02 meters) per revolution. 321km/h = 89.17 m/s* Then 89.17/2.02= 44.14 wheel revolutions per sec. And that's how gauge measures it. But in reality car goes 333km/h = 92.5m/s, 92,5m/s / 2.02m = 45.79 wheel revolutions per sec, and that how gauge should see it to be precise. But too see if that's true we have to make sure that 92.5=104% of 89.17 and that 45.79=104% of 44.14. So 92.5 x 100 / 89.17 and it's ~104%, then 45.79 x 100 / 44.14 ~ 104%. But what about 333km/h / 44.14 will it equal real diameter? As we know 333km/h is 92.5m/s so / 44.14 rev per sec ~2.1m. If 2.02m = 100% 2.1m=? So once again 2.1 x 100 / 2.02 ~104% once again. So yes everything seems correct** :)

    This is example on car with good tires, but covet's factory tires would expand lots more and could even explode, which also works in BeamNG. This game never disappoints realism and physics freaks like me.

    *to convert km/h in to m/s just simply divide by 3.6, to convert from m/s in to km/h just multiply by 3.6 - I've learned this trick by myself and it's 100% correct it helped me a lot in school and not only :)

    ** Wheels in BeamNG aren't actual circles, they are IIRC hexadecagons and my measurement in px is a bit off, because measured diameter in both screens are when wheel was in different angle, and in one there is measurement in angle to angle and in another it's edge to edge, sorry for that.

    ------------------------------------------------------------------------------
    ^Kinda mess but it's really exciting for me that BeamNG is simulating physics that well and soft-body helps a lot in terms of realism.
    ------------------------------------------------------------------------------

    So I'll start now with new example, lots of screenshots not that much of text.

    Note zoom in every screenshot to see what is talked about!


    Subject: Aero in BeamNG pt. 1 - Theory

    I've tested this years ago in Civetta Bolide, but game has come a long way, also aero code was improved. Since we have now "High Climb" variants, which have big wings, diffusers etc. so this cars are armed in aero parts, there are no better config to test it on.

    For screenshots I'll go this way: Vmax, stopped and reversing, then all together - the same camera angle (relative), changed gears ratio to exaggerate effect, so it will be easier too see differences. Please take a look at wing and ride height.

    Vmax


    Stopped


    Reversing


    Look at the angle of wing you'll notice difference, same with ride height at Vmax car was pushed a lot in to the ground thankfully to all the aero stuff, but what is the reason to put them? Obviously more parts equal more weight, more air drag, more downforce equal in higher tire rolling resistance etc. so you'll need more powerfull engine to keep the same acceleration and speed. So, yes, this cars are extremely light and are equiped with beastly engines, and downforce is the key to stay fast... fast while turning. With not much mass and lots of downforce car is cappable of performing some crazy fast driving on corners, because all the aero keep it pushed to the ground, so wheels can hold higher Gforces without loosing grip. And that's how it looks while you merge all the screens together.



    And here at closer camera angle:
    Vmax


    Stopped


    Reversing


    Merged


    Nice detail - look at trunk here and in previous set of screenshots :)

    Ok, we can clearly see that wing done it's job, creating a lot of drag to produce downforce, it also keep car stable at high speeds, if you remove it every manuver at high speeds will be very dangerous, because rest of areo produce downforce in front section of car and will made rear section "too light" so car will drive very unstable, in this situation it's very easy to spinout - but more about it in 2nd part with videos called "Aero in BeamNG pt. 2 - Practice"

    My curiousity didn't ended in this place, what if... FOR SCIENCE!

    Yeah I carefully removed one of the wing supports, to not damage wing and trunk itself, now I'll retry previous test :rolleyes:

    Vmax


    Stopped


    Reverse


    Merged


    Hell yeah! Now you'll clearly see the difference :cool: But one interesting phenomenon here, while going backward wing instead of downforce produce a lot of lift, which also IS realistic. Damn it BeamNG team once again (x100times) didn't disapoint realistic-in-game-physics-lover freaks like me. I bet you can't find any game/simulator that calculates physics as good as BeamNG do.

    More screens with the same test at other camera angles:







    Moreover when you go fast with only 1 wing suport at high speeds car will start turning in to certain direction. If you'll remove left one like I did, at over 180km/h vechicle will turn to left, because of not equal air drag.

    Here's link to whole album: http://imgur.com/a/iRM7y
    All the screenshot were made in 4K, but then I saw that this album would be about 900MB ! So I decided to resize every one in MS Paint to 720p and whole album is now about 13MB, more transfer friendly and will load way faster.

    If you need, feel free to copy and spread it all over the World ;) just leave link to this topic.

    I hope you enjed it, took a while to do. Forgive me my weak English skills. Part #2 with videos comming Soon™. As said above discussion, feedbeck and praising devs are welcome :p
     
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  2. Gamer Alex (AlexKVideos1)

    Gamer Alex (AlexKVideos1)
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    Uh...





    Holy ****
     
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  3. XManic1995

    XManic1995
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  4. Aleferna_dls

    Aleferna_dls
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    What can I say instead of WOW?? I don't know. Probably there aren't words to describe it. This is AMAZING, I mean, how you redacted and explain it, i didn't think about Beamng reality factor, but It's just amazing, I think that many Psychiscs would love beamng if they play it. And how you treated the topic: precise, clear, with images... MAGNIFICENT. I think that I'll probably use this to help me at the highschool.
    CONGRATULATIONS FOR THIS GREAT THREAD :D :D :O
     
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  5. CreasingCurve

    CreasingCurve
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    I had the idea of making a 12 speed DCT transmission with 6 reverse gears so that i could test the loft of the wing on the hillclimb sunburst. It got up to about 145mph airspeed then the back lifting up and it flipped a couple times. It was fun to do.
     
  6. Randomgamer3210

    Randomgamer3210
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    It's the little things like this that make me love his game more and more
     
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  7. Dummiesman

    Dummiesman
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    The aero physics are what make the IndyCar mod I'm converting possible. It's really cool to see that the aero+tire physics in the game allow such things to be possible. :D

    Cool math you've done there with the wheel expansion stuff, by the way. I never really noticed that stuff goes on.
     
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  8. austint30

    austint30
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    Yep, it's proven. BeamNG is the most awesome driving simulator on the entire planet!:D
     
  9. Levy3Poop

    Levy3Poop
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    I've never actually compared any of my IIHS videos to real life videos, but damn if I'm not impressed.

    Here's the 2017 Hyundai Elantra taking the small overlap crash test


    And here's the SBR4 taking the small overlap crash test. Skip to 7:28 for my video. The timed start didn't work :(


    If you pause the IIHS real life video at 18 seconds, and my video at 7:42, you can see that....Damn! It looks pretty close!

    Obviously, my video is a little older, and the physics of the game have improved, but even for an older version of the game (whatever it was on Nov. 10th, 2015) still matches real life pretty well.


    This is a magnificent thread. Let's keep it going!
     
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  10. ClassyClassic

    ClassyClassic
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    That wheel simulation is incredible, I didn't know that!

    I remember when I first had the realization that the aero worked so well. I was taking the Leap of Death in a Sunburst with and without the rear wing. The car nose-dives so hard without the wing, and keeps pretty stable with it!

    Will always love BeamNG! :)
     
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  11. Spec Racer Z

    Spec Racer Z
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    I remember the unique unscripted handling characteristics I got when I knocked the wing crooked on the Capri mod driving up Pikes Peak way back when, though I wasn't in third person view until after the run to see how it may have been moved around by the airflow at speed. Definitely awesome to see such a clear representation of an unscripted phenomenon only currently possible in BeamNG (as far as I know).
     
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  12. TromboneWalrus

    TromboneWalrus
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    Wow! These are the kind of things that make this game amazing.
     
  13. NGAP NSO Shotgun Chuck

    NGAP NSO Shotgun Chuck
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    Idea: going off what you did with the Pessima, is the Bolide Notte's diffuser functional? If it is, how does damage affect its functionality?
     
  14. krayziepunk

    krayziepunk
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    One thing that I feel that is missing is air getting underneath the car and creating lift. I've spun cars out at over 250 MPH in the game and they always stay firmly planted on the ground. I'd like to see improvements where air forces the car into the air, like a NASCAR style blowover. The video gives examples.

     
  15. Nadeox1

    Nadeox1
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    BeamNG Team

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    BeamNG.Drive doesn't have any car that is built like a NASCAR car.
    Those things have a quite unique aerodynamics.
    Their underneath act as a sort of wing and has many diffusers.

    The faster the go, the more the car is attached to the ground or so.
    If the air enters from the opposite side (for example when the car spins out and is going very fast, but with the rear facing the direction), that wing will create an uplifting force, resulting in a blowover.

    On the pigeon, I once tried to put some thrusters.
    The body shape itself would make that little thing take off at around 630KMH.
    I'm quite sure that if somebody builds one of those things accurately, a blowover is quite possible.

    Also, BeamNG.Drive doesn't simulate air as a 'fluid', but takes a simple approach by simply calculating the 'coltris' of a car and how much their are parallel/perpendicular to the direction they are travelling.
    A full fluid-like simulation would probably go beyond the real-time simulation capabilities.
     
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  16. TripleAye

    TripleAye
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    I'd say BeamNG is surely lacking in the aerodynamics department and I'm hoping there is room to improve. Despite Nascars having finely tuned aerodynamics to be stable at controlled high speeds, and perhaps have an even higher propensity to be very unstable at uncontrolled highspeeds (blowovers). I doubt in this current state and with a properly implemented Nascar to the game that you would be able to naturally replicate a blow over. In my extensive testing, blow over simply isn't really possible with how aerodynamics are currently implemented.
    I would like to take the time to praise the Devs for the new hill climb kits as they are simply amazing. The rear wing alone produces 250lbs of downforce at just 100mph, and ~540lbs at 160mph :eek::D Simply amazing, does wonders for car handling. Cars with this kit essentially double their weight at 200mph. Tested in zero gravity ;)
    upload_2016-8-1_23-33-31.png

    So about the blow over, I don't know why it is but 'air' just doesn't seem to interact with vehicles like expected with only drag being a pronounced effect. Now I know there's lift/downforce in game, that explains the planes and helicopters, however, I can't say how they are simulating said aerodynamic forces that make those things work. One could conclude that if you can fly a plane in this game that you can certainly blow over a car right? Well, not really. Granted if you tune the reverse gear in one of the hill climb variants to be closer to the likes of 6th and proceed to floor it in reverse, the rear wing will indeed flip you over at around ~140mph, but for me, this doesn't really count as that is solely a result of the lift being generated from rear wing with no regard to the car itself.
    Ways I have tried to replicate blow over; Back before the grab node camera was set to be stationary and actually moved with the car (something I would like as an option) I would travel as fast as I could in unrealistically powerful cars reaching upwards of 350mph right before the tires explode and proceed to grab a node on the front of the car and gently lift it into the air. Even past a ridiculous negative rake angle of over 30 degrees the car would simple drop back to the ground, as if unaffected by the air that was rushing under the car. I even went as far as to test how long it took the car to touch the ground at rest and at speed. The results were negligible, differences can be attributed to margin of error. I wen't a step further and tried to create extreme cases in order replicated some sort of blow over. I did the same experiment where I drove at high speed and manually lifted the car only this time I simultaneously activated the wind app opposite to the direction of travel and still failed to blow over the car. Mind you that momentarily the speed was a combined 800mph+.
    Since the node grab camera is now stationary I can't do that same experiment at speed, but a lesser version of that can still be attempted using the wind app.
    upload_2016-8-2_0-3-51.png
    As you can see, this car has a pretty gnarly negative rake angle, probably around 10 degrees or so and at 441mph the car remains firmly planted to the ground. Even if you proceed to raise the front of the car high into the air (near vertical) the front will still fall forward. I have noticed as I'm writing this post that the front end is considerably lighter on the front wheels, but this may be attributed to the drag shifting the cars weight towards the rear. This is pretty inaccurate to real life. Side note: I put the front splitter on the custom Sunburst configuration pictured above with the large rake angle, and it still produced down force. This doesn't seem right at all.
    My conclusion is that the angle of attack isn't really having much of an effect, even more so, ground effect is most likely non existent, which are the main reasons why cars blow over in the first place. With enough speed, increased ground effect, and angle of attack you can blow over any car. I should reiterate that angle of attack isn't completely nonexistent, it just doesn't have enough on an effect to overcome gravity. I tested this in zero gravity and at the highest wind speed. The Sunburst did correct and try to keep itself horizontal as pictured below.
    upload_2016-8-2_0-47-39.png
    I think it would be safe to say that some sort of ground effect implementation would make it so that cars can blow over. Also, if angle of attack had a more pronounced effect I think handling in general would improve some as well. "A full fluid-like simulation would probably go beyond the real-time simulation capabilities." Does this mean what we have now is it? Can you offer any further insight to some of inadequacies that exist in the current aerodynamic simulation? As I don't think that adding a Nascar to the game would have all that much of an affect. Please use this as an excuse to prove me wrong;) A official Nascar from you guys would be just so cool. Not to mention easier to model, right? Anyways, love your work, keep improving it!
     
    #16 TripleAye, Aug 2, 2016
    Last edited: Aug 2, 2016
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  17. krayziepunk

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    Fantastic reply TripleAye! I did similar experiments with the node grabber before the camera was changed. I would get it side ways at over 200 MPH and lift the side of the car up and it would immediately come back down. As you demonstrated, at those insanely high speeds SOMETHING should happen, but it doesn't. The bottom of the car just doesn't seem to interact enough with the "air".

    I second having an official NASCAR style stock car in the game! BeamNG.Drive needs some official purpose build race cars, instead of just modded street cars.
     
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  18. Davded

    Davded
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    The aerodynamic simulation in BeamNG is a difficult problem, unlike other games and simulations, the geometry is constantly changing. This means these complex effects can't just be defined in hardcoded models for each vehicle like how almost every other game/sim does it. (eg, handling lines in GTA, reduced order coefficents etc.)

    Currently the triangles which have aero forces applied are all considered individually (as if nothing else exists), therefore cannot represent the vehicle as a whole. This means fluid effects like ground effect, induced drag, separation, shadowing, vorticity, boundary conditions, interference etc. will never be represented. Ground effect and induced drag are probably the two most important for beamNG, all the cars are obviously close to the ground, and so experience it and lack of Induced drag severely cripples the realism of aircraft in the game. There is also the issue in that when a car loses body parts, it will have a higher drag because of the rougher shape, currently the drag will just get lower because the body panels are no longer there.

    One method of solving these problems (or at least improved) is with a panel method, such as a Vortex Lattice Method (VLM), which would consider the entire 'shape' of the vehicle, not just individual elements. However, this basically centers around equating an n by n matrix, where n is the number of panels. If a car has say, 200 panels (tris/quads), then we need to solve a 200 by 200 matrix, which is basically 40000 operations. No way that can be done 2000 times a second and have all the beam physics going at the same time. Not only that, the standard way of simulating ground effect is by reflecting the vehicles shape across the ground plane, so you would end up with (200+200)^2, or 160000 operations... yeah, not happening, at least not at 2000hz. The normal shortcuts that are used in CFD, like only simulating half a symmetrical car/aircraft can't be applied in BeamNG because of the ever-changing geometry. If two cars are for example 'drafting', this would quite easily be simulated, but again the computational requirements would be squared, not just doubled.

    Cutting the panels used to say, 50, will make a big difference and is certainly close to real-time simulation requirements, however the accuracy will certainly be effected. Here is an example of the Bolide, but using only 52 panels:
    bolidepanelled.png

    If using a low number of panels could still get accurate results, then maybe it would be possible to run at the same frequency of the physics. And obviously, if parts are going to be detached/move, there is a whole other problem if for example one of the doors opens, or the bumper is hanging off, the aerodynamic panels would need to dynamically split and form new geometry to represent this.

    For aircraft, induced drag can be added if whole wings can be defined as as series of joined sections using something like Prandtl Lifting line theory, this would be no problem to simulate in real time and would be accurate for wings that are not occluded, eg aircraft wings. Note that induced drag is not the same thing as the component of drag from the 2D lift/drag vectors, it is a 3D effect that accounts for the energy lost in the downwash/vortex sheet of a surface.

    TL,DR: Accurate aero is difficult and a fluid simulation cannot be run at the same frequency as the physics unless some serious trickery is done. A blow-over is a good example, because it is easily one of the hardest effects to be simulated in a CFD package, let alone something that has to run in realtime and not in terms of days/hours for a 30 second run. It probably could be simulated in BeamNG right now, but it would certainly be 'hacky', eg, hidden wing/drag surfaces.

    Some stuff would be solved relatively easily with specific 'wing' sections for thin aero surfaces, and possibly look at doing some localised vortex work which would correctly simulate ground effect of things like front wings & splitters of an F1 car or aircraft near the ground.
     
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  19. krayziepunk

    krayziepunk
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    Thanks for the detailed write up. What I'm curious about is how this effect was achieved in Rigs of Rods. Video:


    I had something similar happen in RoR when using a fast car and hitting a bump. The car would lift higher and eventually crash back down.
     
  20. estama

    estama
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    BeamNG Team

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    Davded you've wrote about the aerodynamics simulation subject a lot better than i could. Thank you :).

    I've just wanted to add that there is an aero debug in the latest version activated with coltri debug view.

    Concerning more advanced aerodynamic simulation methods, we are doing research on them. I cannot give any specific timeline (lots of other things have higher priorities, so i cannot spend too much time on the aero), but we might be able to advance the aero simulation some more. By saying "some more" i hope that each triangle's aerodynamics will be affected by the rest of the vehicle's geometry, in essence having an approximation of global (to the vehicle) aero-effects.

    I cannot promise anything though (it is a very hard/complex subject). Research is hard and unpredictable.
     
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