Author Topic: St. Jimmy's vehicle feedback about aero and inertia  (Read 815 times)

St. Jimmy

  • *
  • *
  • Posts: 1130
I was playing around with BagEditor to observe things more. I've couple of questions and feedback for you:



Aero and mass on air time:

Why aero affects so much in jumps/air time but mass distribution doesn't really have an effect? Shouldn't it be the other way around? I can't find how I could make the mass be one of the main things and then make the aero actually fight against the mass. Currently it's the other way around, aero decides how the car behaves in jumps and mass has little to no effect.


I've a feeling that in Sandpit 1 Route 2 jump that the front engine cars rotate backwards and rear engine car rotates forward right at the beginning of the jump. Then the aero comes in play more. There is something wrong with this. I also noticed that if I change the front mass distribution parameter only, the cars start to rotate the opposite. Isn't that kind of a wrong behavior?

You shouldn't go in shortcut and just change the front and rear lift parameters to counter the air time. It can make the cars behave totally wrong when on the ground. You need to fix the bug(s) in your physics or parameters first so mass have more effect and aero little. Then just apply realistic aero and it's done.

--------------------------------------------------------------------------------------------------------------------------------------------------------------

Aero Drag Scale In Air:

Does this affect much or anything when the car isn't really in airtime? It could solve some of the problem with how much aero have an effect in the air if it gets lowered a lot.

--------------------------------------------------------------------------------------------------------------------------------------------------------------


Front/Rear Lift

You said that old cars that you've in the game have actually lift. It's a wrong thing to say that at least on all of the cars. That's likely wanted behavior on FF cars. You put lift on the back on every car.

Here's a picture of '69 Chevy Camaro lift/downforce:

Open and zoom it if you need.

Notice that it has lift on front and downforce in the back.

I was also googling more and found an interesting claim about American 4 car if I'm right? http://www.musclecarclub.com/pontiac-firebird/
Quote
At the top was the Trans Am, which was fitted with air dams across the bottom of the front and in front of the wheels. A large decklip lip and small spoilers in front of the rear wheels completed the package. These aero pieces were claimed to generate 50 pounds of downforce on the front and rear of the car at highway speeds.



I bet that everyone of those cars in the game have lower lift in back than in front or even small downforce in the back because of how cars are in general. Some of them have some aero parts to make the back lift actually likely pretty low lift or even minor downforce or sometimes even increase the downfocre, depending on a car we are talking about. Currently you've set the back of every car to have lift. Having lift on front is a right thing to do mostly but as I said AM4 (and maybe AM1) might actually have downforce but that's just because they're so well designed and have good aero parts.

Here are also some American cars wind tunnel tests that shows lift and downforce:
http://www.autofocus.ca/news-events/features/the-69-daytona-is-as-slippery-as-a-new-charger-hellcat

I wonder if someone could find that kind of stuff about the European cars to get some actual facts?


--------------------------------------------------------------------------------------------------------------------------------------------------------------

Inertia

I was playing around it and found the reason of the behaviour that I don't like in the game. It's the Z component of the Moment Of Inertia. It's way too low. I know that you likely want to have some roll back feature and don't want to make the cars to roll over easily but this is TOTALLY WRONG WAY to do it. Roll back feature is naturally unrealistic and should be an option do do some other way. It also makes the cars feel like unflippable from bumps or momentum that should roll or lift the wheels off the ground. Too low Z inertia ruins everything about the feeling of the car. It makes the handling awfully snappy.

Making the Z inertia higher makes the car handle better in a way that you don't get a sudden grip-no grip-grip-snap-I'm spinning but it still doesn't make lap times better or cars faster, pretty much the opposite. Increasing the Z value makes everything feel more natural driving/handling of the car is more naturally proggresive, not like it has been for long that you suddenly spin or loose some control because of a sudden artificial snap of a grip. You can actually countersteer when you increase it. Can't countersteer because of the snapiness has been one of the biggest problems that this game has had.

I quickly tested some Z inertia values and I gave the Euro 1 increase  203->700. I feel like 500-900 is more realistic in this game for most of the cars because AM3 could take 900 and it doesn't flip way too easily.

I can upload some mod later about this inertia stuff so you (community and/or BB) can feel what I'm talking about and if you're not willing to make easy small mod of it by yourself.

--------------------------------------------------------------------------------------------------------------------------------------------------------------



Thank you for reading and hopefully you'll sort things out.
« Last Edit: August 06, 2016, 03:52:18 PM by St. Jimmy »
Join WreckFest Discord!

Contribute to the WreckFest wiki!


i7 2600K @ 4,7GHz
GTX 1070 8GB
16GB CL9 2133 MHz
750W PSU
Win7 Ultimate 64-bit
Fanatec CSR

Daystar

  • Posts: 2169
Thank you St. Jimmy in your well explained post about the snap back (jerky) steering conditions! Very noticeable with the AM1 car and I am a keyboard player.  Am1 used to be my fave car, but I had to resort to the AM4 car, which handles oddly much better than the AM1. Looking forward to you making a mod, that will hopefully enable me to play with the Am1 car again, without crazy steering issues.  :)

BrianUK

Lift on the front needs to be counteracted by weight distribution though. The AM1 has a front splitter which creates downforce on the front end, which would help mitigate most lift generated, then the engine/transmission/suspension/brake weight on the front would deal with the rest.

St. Jimmy

  • *
  • *
  • Posts: 1130
Lift on the front needs to be counteracted by weight distribution though. The AM1 has a front splitter which creates downforce on the front end, which would help mitigate most lift generated, then the engine/transmission/suspension/brake weight on the front would deal with the rest.

Yeah the mass should play bigger role in the air. I've hard time to believe that the lift values should be small like +/- 0.0001 so it won't effect too much in the air. Having lift on front and down on back with bigger numbers already have too much of an effect over the mass. Likely those small numbers don't matter anymore even on the ground...

Some kind of response from BB would be nice.


Also can you BB share how you've calculated the inertia and center of gravity values? I guess they're not close to real data? At least the Z value is maybe bit small and CG looks bit low but I don't really know things too much.
Join WreckFest Discord!

Contribute to the WreckFest wiki!


i7 2600K @ 4,7GHz
GTX 1070 8GB
16GB CL9 2133 MHz
750W PSU
Win7 Ultimate 64-bit
Fanatec CSR