Physics The Physics discussion thread

[William Levesque]

Welp

 

[Amir Vodokotlic]

If you're going to link to apr wing at least link it properly with cfd data tables/graphs

http://aprperformance.com/racing-product/gtc-300-adjustable-wings/

also why not post your data.acd file so guys like David/McLaren/Stereo etc can look it over, you seem be so sure everything you're inputing is 100 percent accurate.

 

[mclarenf1papa]

And to be sure I think will just stick with AC for the mod for now, just to upset folks that might otherwise think running me off will change the fact that AC is not a modular sim engine after all

No, folk just think that running you off might just raise the IQ average of the forum a bit...

 

[RC45]

@SportRotary

I'm still genuinely curious as to what is lacking in the "feel" of your C5 model when you use real-world parameters. How does the steady-state balance of the car (understeer/oversteer) compare to your experience? How quickly does the car react on turn-in? Can you feed in power on corner exit like in real life? How does the car react to curbs/bumps?

I never said I didn't have the car behaving perfectly - I do. It is exactly like the way I know the car to be at various power and tire setups.

This was how ever achieved by using chassis adjustments outside of the normal envelope.

Tweaking tire values is outside the norm.

But as I said earlier, if AC has such a poor engine that it needs per tire tweaks so be it. I just fudged the numbers till the car did what it was supposed to - the same way everyone else does.

If the above characteristics don't match reality, you have a lot of knobs to turn and you need to make sure each parameter really matches reality: wheel rates, damping (don't forget to factor in the motion ratios), suspension kinematics (roll center heights, roll center migration in bump/roll, camber curves, trail/SR, caster, KPI), ARB rates @ the wheels, CG height, CG location, etc. etc.
Really - if as has been revealed that AC does not even simulate or model suspension kinematics why spend resources here? Is is because you just wanted to type some jargon ? When I asked how camber was represented someone suggested AC treats the as if it was on a ball joint at the end of the axle.

In an adjustable suspension model camber can be set by moving the a-arm pickup points which alters the track the track - calculating and measuring all these movements when the sim engine ignores them is pretty pointless.

Considering AC uses a very abbreviated suspension model the reality is you could have arrived at the same results you did just by fudging the numbers instead of doing all that work.

The result is exactly the same - a car that "feels" right.

Representing each one of those parameters by lines in a text file isn't trivial, and I would venture to say that even the most skilled race engineers would spend well over 100 hours measuring, testing, and characterizing those parameters to input into a sim. As an added complexity, obviously AC isn't running an FEA in the background, so the compliance of the parts must be accounted for (the stiffness of the ARB bushings must be accounted for when calculating the stiffness of your ARBs, for example).

If you think there's really a major flaw in AC's physics engine, list out the parameters I described above and prove that they match your measurements. Measuring the length of the control arms and taking some pictures of the suspension assemblies is maybe 5% of the measurement work that's needed. You need to present more objective data if you want anyone to take your argument seriously. If you can make a case that you've accurately measured all of these parameters, and that you've accurately represented them in AC; then we'll all bash the AC physics engine together

I don't need your or anyone else's validation or approval mate - that note page and few photos represented less than 5% of the total effort expended - as I say, don't need your validation, I already have a well behaved working car in game.

In the end it was piss easy to do - I just fudged the numbers till it felt right. Problem solved yeah.

 

[Fat-Alfie]

First time I've ever hit the "ignore" button

 

[RC45]

No, folk just think that running you off might just raise the IQ average of the forum a bit...

Mod Edit: Offensive behaviour is not on.
it turns out all you have been doing is fudging numbers to get cars to behave as desired in game? You guys sure are quick to display mob mentality. Gang up on any one that even suggests AC isn't the be all and all of PC titles.

BTW, shouldn't you be off fudging numbers for your next car release?

 

[RC45]

If you're going to link to apr wing at least link it properly with cfd data tables/graphs

http://aprperformance.com/racing-product/gtc-300-adjustable-wings/

Why? You struggling to understand the context of the rendered results in image form?

also why not post your data.acd file so guys like David/McLaren/Stereo etc can look it over, you seem be so sure everything you're inputing is 100 percent accurate.

Why? The car is fantastic in game. Behaves exactly as expected. It 'feels' perfect - so why should the fudged numbers needed to achieve these results matter?

Over the last 6 pages I have been told countless times to "just change the values" so I did. Mission accomplished.

 

[RC45]

Mods, you can lock the thread now thanks - its run its course. My original question as to why the results where not as expected has been answered - just fudge the tire numbers till the car feels right, which is what I did. Problem solved.

 

[mclarenf1papa]

Mods, you can lock the thread now thanks - its run its course. My original question as to why the results where not as expected has been answered - just fudge the tire numbers till the car feels right, which is what I did. Problem solved.

It's not your decision to make either way....

First time I've ever hit the "ignore" button

Missing out. The sheer ineptitude (or trolling...can't really tell) is fairly amusing at this point.

 

[Michael Hornbuckle]

Wow, you must be the best physics guru of them all if after 100 hours all you had to do was change a couple numbers in a couple ini files and now your telemetry matches perfect; you even managed to test and approve the results all in just a couple hours. Damn shame that you are going to keep the mod for personal use because I have no doubts that it would be a game changer if released.

 

[David Dominguez]

Actually it was me who opened the thread.

 

[David Dominguez]

Mods, you can lock the thread now thanks - its run its course. My original question as to why the results where not as expected has been answered - just fudge the tire numbers till the car feels right, which is what I did. Problem solved.

Do you have tyre data?

 

[SportRotary]

@RC45

You still haven't answered my question. When you input the parameters that you measured from your car, what exactly is lacking in the handling of the C5? You keep saying that you had to increase the camber beyond the factory envelope, yet you don't reveal the original issue when real-world parameters are used. All I'm suggesting is, it's a complex model, it will never be perfect, so maybe there's an inaccuracy with how you modeled one of the many, many other parameters that go into the model. Fudging the camber may just be offsetting an error in another part of the model .That error could be from you, or it could be from Kunos. Since you're not willing to share your data, we can't say for sure.

Regarding the camber adjustment; ok, an assumption was made by Kunos to simplify the model, so they didn't account for movement of the LCA location. It's not some monumental shortcoming, it's just an assumption that greatly simplifies the model; 99.99% of people won't be able to feel the difference. Imagine how complex the kinematics model would be if they included the camber adjustment strategy of every car in the game (inboard eccentrics, outboard rod ends, inboard shims, outboard shims, mac strut camber plates, mac strut eccentric bolts...). Now you would have to quantify (in addition to the location of each suspension point) how that asjustable point moves the rest of the suspension points in 3D space when the given mechanism is adjusted. So now the kinematics model is at least twice as complex as the simplified method (increasing their own workload and turning off many modders who don't have access to that level of data), but they've only made minuscule improvements to the accuracy of the model. The value they would be getting from that added complexity would never be worth it, so I say that simplification is totally valid.

 

[garyjpaterson]

@RC45

You still haven't answered my question. When you input the parameters that you measured from your car, what exactly is lacking in the handling of the C5? You keep saying that you had to increase the camber beyond the factory envelope, yet you don't reveal the original issue when real-world parameters are used. All I'm suggesting is, it's a complex model, it will never be perfect, so maybe there's an inaccuracy with how you modeled one of the many, many other parameters that go into the model. Fudging the camber may just be offsetting an error in another part of the model .That error could be from you, or it could be from Kunos. Since you're not willing to share your data, we can't say for sure.

Regarding the camber adjustment; ok, an assumption was made by Kunos to simplify the model, so they didn't account for movement of the LCA location. It's not some monumental shortcoming, it's just an assumption that greatly simplifies the model; 99.99% of people won't be able to feel the difference. Imagine how complex the kinematics model would be if they included the camber adjustment strategy of every car in the game (inboard eccentrics, outboard rod ends, inboard shims, outboard shims, mac strut camber plates, mac strut eccentric bolts...). Now you would have to quantify (in addition to the location of each suspension point) how that asjustable point moves the rest of the suspension points in 3D space when the given mechanism is adjusted. So now the kinematics model is at least twice as complex as the simplified method (increasing their own workload and turning off many modders who don't have access to that level of data), but they've only made minuscule improvements to the accuracy of the model. The value they would be getting from that added complexity would never be worth it, so I say that simplification is totally valid.

This.

Please understand you are playing a consumer product which retails for less than £25, designed to be able to model many different vehicles to a very respectable degree of accuracy. It it perfect? Nope, but its pretty great considering the price point. Compromises are made all the time, and its up to Kunos to find the balance; I happen to think they've done a damned good job of it too, but its within your right to think otherwise.

If you want a professional sim, by all means buy one, but don't expect the world from something that is at the end of the day an entertainment product.

 

[Jim Layee]

He got the same reaction over on the official forum and said he was going to play with the big boys over at Rfactor instead.

But seriously @RC45 when everyone else disagrees with your analysis and conclusions it usually a great sign that you've headed off at the incorrect angle so take a breath and have think about where you're heading .
Also I for one would love a C5 created by an owner who obviously has a passion for that so don't think the whole world is against you.

 

[RC45]

It's not your decision to make either way....


Missing out. The sheer ineptitude (or trolling...can't really tell) is fairly amusing at this point.

My bad - I forgot to post video of the car on track - it handles just like in real life

 

[Chris]

RC45,

You have several people giving up their free time to try and help you resolve your situation, it'd be in your best interest if you didn't (metaphorically) spit in their faces.

Warning point added for your conduct in post #86.

As for locking this thread... No, it will not be locked as people may have some genuine physics questions of their own. This thread was not created just for your dilemma alone.

 

[William Levesque]

Too bad we can't tell how it handles since it's never at the limit....

 

[RC45]

RC45,

You have several people giving up their free time to try and help you resolve your situation, it'd be in your best interest if you didn't (metaphorically) spit in their faces.

Warning point added for your conduct in post #86.

As for locking this thread... No, it will not be locked as people may have some genuine physics questions of their own. This thread was not created just for your dilemma alone.

Hmm not sure what was exactly in violation of ToS as you deleted it - I did not attack anyone, threaten anyone or insult anyone - even though everyone from Kunos on down have had a go at me in one way or another I have not retaliated in kind - I just sit and take it.

As for the thread do what ever you will as its your forum, but the way these folks have been piling on like a mob you could have sworn the thread was opened just for convenient vehicle to run me over.

 

[RC45]

Too bad we can't tell how it handles since it's never at the limit....

Yeah - isn't it amazing how being smooth and not over driving a well setup street car can still allow for 130mph+ on a short track and average 1.2g cornering with 2g peaks and still barely any tire squealing. Thanks for noticing that by the way - not everyone can appreciate a well setup car being driven smoothly at speed