Physics thread

  • Thread starter LVracerGT
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JohnScoonsBeard
SMS have said themselves that they don't render (or make renderable) the rear of the car in cockpit view as it's wasted processing that could be used elsewhere. I was quite surprised at how much still did get rendered on the car the further I moved back. The seat position on the Yellowbird is one of those bugs/features I hope they add on all cars. It was fun driving the car when underneath it.
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Is it possible to see the modeled part of everything behind the front seat of the car ?
 
Ridox2JZGTE
Is it possible to see the modeled part of everything behind the front seat of the car ?
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I didn't use the look up or down buttons as I can't remember what I'd mapped them to. I think I looked around as much as I could and did use the seat angle up or down buttons. Not sure I could see a lot more than I did in the video. I certainly went as far back as I could in the car.
 
NLxAROSA
The discussion regarding camber I started earlier in the more private parts of the forum has more or less the same conclusions after some members did some extensive testing. SMS is aware of it. Let's see if/when this leads to a fix.
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A bit more info on this (without going too much in to detail since I'm not sure what I'm allowed to share or not): the devs are not only aware, but actively testing along with very detailed input from a few WMD members. Let's just say I would not be surprised if this would lead to action some time in the near future.
 
NLxAROSA
A bit more info on this (without going too much in to detail since I'm not sure what I'm allowed to share or not): the devs are not only aware, but actively testing along with very detailed input from a few WMD members. Let's just say I would not be surprised if this would lead to action some time in the near future.
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This great to hear!
 
NLxAROSA
A bit more info on this (without going too much in to detail since I'm not sure what I'm allowed to share or not): the devs are not only aware, but actively testing along with very detailed input from a few WMD members. Let's just say I would not be surprised if this would lead to action some time in the near future.
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Are they testing the straight line effects as well?
 
NLxAROSA
Yes.

@Ridox2JZGTE : Not sure if caster is involved.
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Caster should be in the physics, when the front wheel is turned and positive caster, there should be camber gain and it affects the inner wheel as wheel as well outside wheel ( turn in, grip + load ) Road condition also will have great effect ( banked turn, dip in the apex, curb etc ) Cars with high caster would benefit from lower steering ratio ( faster turn lock to lock ) to make use the added stability ( centering more pronounced ), but this really depends on the driver too.

Past discussion about centering on the wheel and camber benefit in corners vs straight line might be largely affected by how caster is simulated :D Picture both axle camber has their own pros and cons, rear camber ( rear grip on corner vs straight line braking/accel, tire wear/even temp ) and front camber ( turn in, corner grip/contact patch, tire wear/temp, braking / corner entry )


This is a good read about caster, camber and toe :) Just basic easy to understand article :

http://www.aligncraft.com/terms/terms.html



Caster Definition
Caster can be defined as the forward or rearward tilt of the projected steering axis from true vertical, as viewed from the side. This line is formed by extending a line through the upper and lower steering knuckle pivot points. For vehicles with front control arms, visualize the line extending through the upper and lower ball joints. On strut equipped vehicles, the line extends through the lower ball joint to the center of the upper strut mount. Caster is always viewed from the side of the vehicle.When the upper pivot point is rearward of the lower pivot point, caster is positive. If the upper pivot is forward of the lower pivot point, caster is negative. When the two points are straight up and down from each other, the caster is zero. A maximum side to side variation of ±.5° is recommended on most vehicles. Caster is NOT a normal tire wearing angle and is used as a directional control for stability and steering returnability.

caster.gif

Front of Vehicle Caster Effect

Caster effect is necessary so that the load of the vehicle is "carried" through the steering axis line formed on the upper and lower pivot points. Positive caster gives a vehicle directional stability because the tire is being pulled along by the load which is projected in front of the center of the tire contact area. This causes a vehicle with positive caster (point of load ahead of the point of contact) to be harder to steer away from the straight ahead position. With Positive caster, road surface variations have a minimal effect on the tire, the tire will continue to go straight. When a tire has a Negative caster condition, where the projected steering axis point of load is behind the tire point of contact, a vehicle will have a tendency to be easier to steer but will lack directional stability. A vehicle with negative caster is affected by any road surface variation such as small road irregularities or bumps. With the point of load pushing the tire along (negative caster), any bumps or road irregularities which are encountered have a tendency to immediately affect directional stability and vehicle handling.


Front Caster Effects
Effects of Positive Caster
Vehicles usually have some positive caster specified since this promotes directional stability, however, excessive positive caster can cause two problems. The first is that excessive caster will cause a high level of road shock to be transmitted to the driver when the vehicle hits a bump, etc. The second problem is that a tire/wheel assembly with positive caster has a tendency to toe inward when the vehicle is being driven. If one side has more positive caster than the other, this causes it to toe inward with more force than the other side. This will cause a lead or pull to the side with least amount of positive caster.

Effects of Caster on Tire Wear
When set with a substantial amount of caster, the spindle travels in a vertical arc, causing it to move up and down and raise and lower the wheels as the steering wheel is turned. Because of this, camber changes occur. With a high amount of positive caster, the camber changes that occur, especially at low speeds in tight turns, cause the tires to show wear on their shoulders. In high speed cornering, the vehicle tends to continue straight ahead when the steering is initially turned. Due to this, and the amount of camber change that takes place when a spindle travels through its arc of travel, the shoulders of the tires on a vehicle may scrub and wear. When a left turn is made at a fairly high rate of speed with a vehicle which has positive caster, the caster of the left front wheel changes toward positive but the momentum of the vehicle is in a straight ahead direction. This causes the inside of the left front tire to scrub as it is turned. Just the opposite effect takes place on the right wheel as the vehicle is turned left at high speed. The right front wheel's camber will go negative but the outside edge of the tire is scrubbed because of the vehicle's momentum to go straight. On some vehicles setting caster more than +2.5° will cause scrub problems.

And caster + camber use in stock car :

http://www.joesracing.com/rt-4189-caster-creativity.html

  • Caster is measured in degrees
    Caster is measured in degrees. When a line is extended from the top ball joint through the bottom ball joint the caster line is created. Zero caste would be when the upper and lower ball joints create a line that is perfectly vertical. Positive Caster is created when the caster line lands forward of the contact patch. Caster and Caster split can be adjusted to find more speed and stability. A common example of caster is a shopping cart. As the shopping cart is pushed forward the front wheels spin back and trail behind the caster line.

    Caster creates stability as the geometry created forces the wheels back to straight. The front wheels are “encouraged” to stay straight as turning them involves lifting the car weight. Expensive street cars often have high amounts of positive caster providing them with a superior and stable feel. The drawback comes in the form of added steering effort. The invention of power steering has allowed for more caster to be added. When power steering fails it is easy to see the negative effects. As soon as the dripping wet driver gets out of the car and asks for help opening a beer due to his arms being worn out it becomes clear how power steering has allowed higher amounts of caster.

    In stock cars, we can use caster to help our cars going beyond simple directional stability. Caster split is often used as a chassis adjustment. Running more positive caster on the right than on the left is common. The question is how much split and how much positive caster should you run?

    Caster split and the appropriate amount chosen is one of those chassis adjustments where there is not a magic amount or a right or wrong answer. If you understand the effects of caster split you can make your own decisions based on your track, driver and goals. Commonly crew chiefs run 3 degrees positive on the right side and 1 degree positive on the left side. At times it may pay to run 4 or 5 degrees on the right and .5 degrees positive on the left. It all depends on what you are hoping to accomplish for your specific chassis needs.

    An often overlooked element relating to stock car caster is that the more positive caster you run the more “beneficial” camber gain you will get. As the car rolls you will see more negative camber gain on the right side and more positive camber gain on the left in lock step with running additional caster. Camber gain through travel is typically a good thing but like all adjustments you want to avoid going too far. If you are aggressive with A-Arm lengths that create high amounts of camber gain you want to be careful that you do not get to aggressive with caster. As always balance applies.

  • T134274447.jpg
    Speed Secrets
    You can find a "speed secret" by understanding that more caster beneficially adds to negative camber gain on the right front and more positive camber gain on the left front. You can check this effect by measuring your camber gain at your current setting and recording the numbers. Next - add caster and check your camber gain again and you will see the benefits visually right in the shop. With the knowledge you can tailor your set up package to overcome obstacles presented by your car, track and driver.

    To visualize the benefit of the caster induced camber gain it pays to think in extremes. If you are running 3 degrees of positive caster on the right this would be in the normal range. For our visualization, picture adding caster until the caster line is adjusted an exaggerated amount until it becomes completely horizontal. At this hypothetical and exaggerated point, the result would be pure camber change instead of directional change. The benefit is that with more static caster, the right front wheel would gain more negative camber as steering input is increased. The left front wheel gains more positive camber as the wheel is turned. Cool, we get more camber gain when we need it most by running more caster through a left hand turn! Even experienced crew chiefs can be unaware of the relation to caster and beneficial camber gain in left hand turns. Personally, I find understanding the camber gain from caster to be a true “speed secret”.

    Running more caster on the right side verses the left is an adjustment tool that can help cars turn left. The amount of caster split can create benefits as the wheels are turned. More split will “de-wedge” the car at maximum steering input helping the car to turn in the middle. As the steering wheel is un-wound - wedge is added back helping the car to hook up better on exit. Wedge is added back as the wheels return to straight or even back through to the right. You can easily see this change when you have the car on scales. The next time you weigh your car and you have recorded your race ready numbers simply turn the steering wheel 10 degrees left and you will see your scale numbers display less wedge when the wheels are turned left.


Most of Pcars default setup has high caster around 6 - 7 degrees.
 
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There doesn't need to be follow up, this is normal procedure on Pcars forum. If someone raises a genuine issue, a mod will acknowledge if it's a known issue or if the devs are looking into it, and no more info is given until there is a solution.
 
Mike_grpA
There doesn't need to be follow up, this is normal procedure on Pcars forum. If someone raises a genuine issue, a mod will acknowledge if it's a known issue or if the devs are looking into it, and no more info is given until there is a solution.
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I'm aware of that, but a progress info would have been better, like have the cause been identified or not :)

I'm a member on the Pcars forum, but when I click on that link that texastyme214 posted, it does not give me access to view it :(
 
That's because it's from the WMD lounge, which is limited to WMD-members. The limited progress information that I have been feeding in here comes from that thread (devs post in there too). Short summary: they are aware of the issue and have a good understanding of what's going on exactly. No ETA on a fix yet.
 
Those patch notes are impressive!

It wasn't long ago that the enormous 3.0 patch came out, and already they've released another monster.
 
Mike_grpA
It wasn't long ago that the enormous 3.0 patch came out...
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Talking of 3.0, where are the default FFB settings? I heard that we would have a choice of several different defaults, but I can't find them anywhere.


:confused:
 
http://forum.projectcarsgame.com/showthread.php?39365-bmw-320-gr-5


Interesting discussion by Casey Ringley, the lead physics about how the toe accumulates and causing issue like wandering steering, crash ( land mines ? ) and floating cars.

Sadly the supposed fix was not included in 4.0. What Casey said :

"We tracked down this bug late last week. Nasty one; could be responsible for a lot of the physics explosions people have reported in long sessions. For some reason, this car does (did) a similar thing in much less time."

"Code. Appeared to be drift caused by accumulated error in the suspension geometry solver. A periodic check to make sure it was all behaving has cleared up the problem completely."

"Watching toe angles change as race distance accumulated and then magically reset on even very small collisions. For whatever reason, only the 320 Turbo had this happen at a rate fast enough to be noticeable and data fixes alone only minimized it. On the bug, it picks up something like 0.2° per side per lap at Silverstone. So by lap 10 you'd be up over 4° total at the rear end - hence the wandering! That's a good sign that pickup points were shifting around slightly over time in an unpredictable manner. Feeling pretty good that it will help the other issues we've seen where cars start spontaneously crashing and floating. The videos we've seen look exactly like what happens if we balls up the suspension geometry and put a wheel into an unconstrained state. That makes sense if the points were going walkabout on their own. Haven't seen any sign of the issue since Steve made the fix."

"No idea on the logistics of a hotfix patch like that...not my area. Well the good news is that the effect accumulates very slowly on most cars and does reset during pit stops. Messy band-aid, but you could also very lightly scrape the wall at some point and it also resets any bad drift."
 
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VBR
Talking of 3.0, where are the default FFB settings? I heard that we would have a choice of several different defaults, but I can't find them anywhere.


:confused:
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Yes it's there in the wheel menus but what I had really hoped for was some sort of visual representation to show how the new FFB was different. As it is you can choose custom, default or classic from the wheel control screens but when you go back to the car FFB set up it all looks the same.

Regardless, I tried the new settings and didn't like them still so it was back to Jack Spades-esque for me.
 
Ridox2JZGTE
http://forum.projectcarsgame.com/showthread.php?39365-bmw-320-gr-5


Interesting discussion by Casey Ringley, the lead physics about how the toe accumulates and causing issue like wandering steering, crash ( land mines ? ) and floating cars.

Sadly the supposed fix was not included in 4.0. What Casey said :

"We tracked down this bug late last week. Nasty one; could be responsible for a lot of the physics explosions people have reported in long sessions. For some reason, this car does (did) a similar thing in much less time."

"Code. Appeared to be drift caused by accumulated error in the suspension geometry solver. A periodic check to make sure it was all behaving has cleared up the problem completely."

"Watching toe angles change as race distance accumulated and then magically reset on even very small collisions. For whatever reason, only the 320 Turbo had this happen at a rate fast enough to be noticeable and data fixes alone only minimized it. On the bug, it picks up something like 0.2° per side per lap at Silverstone. So by lap 10 you'd be up over 4° total at the rear end - hence the wandering! That's a good sign that pickup points were shifting around slightly over time in an unpredictable manner. Feeling pretty good that it will help the other issues we've seen where cars start spontaneously crashing and floating. The videos we've seen look exactly like what happens if we balls up the suspension geometry and put a wheel into an unconstrained state. That makes sense if the points were going walkabout on their own. Haven't seen any sign of the issue since Steve made the fix."

"No idea on the logistics of a hotfix patch like that...not my area. Well the good news is that the effect accumulates very slowly on most cars and does reset during pit stops. Messy band-aid, but you could also very lightly scrape the wall at some point and it also resets any bad drift."
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This is really good news man thanks for sharing! As I've said before, I haven't experienced this issue personally, but no doubt I would have at some point.

This was the one they couldn't reproduce, so the fact that they've not only spotted what causes it, but fixed it as well, is huge news for people experiencing the landmines and floating cars. I expect they'll add this to PC very quickly, and consoles in the next patch. Would be great if they did a small hotfix for consoles though, as it's a big problem for a lot of people.
 
bleeder
Yes it's there in the wheel menus but what I had really hoped for was some sort of visual representation to show how the new FFB was different. As it is you can choose custom, default or classic from the wheel control screens but when you go back to the car FFB set up it all looks the same.

Regardless, I tried the new settings and didn't like them still so it was back to Jack Spades-esque for me.
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All I can see is Defualt or Classic. Not what I would call presets. Lame.


:(
 
FLX1981
If you modify any of them, it generates a third, custom one. How many do you need, exactly? :rolleyes:
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I was expecting several that would cater for most peoples taste, & was looking forward to trying them all out.
 
If you want to try my ffb settings @VBR just hit me up. I use a CSR so not much different to your wheel. Just let me know and I'll pm you with all the details next time I'm on the game :)
 

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