There are quite a lot of papers out there. Dr. Pacejka released a book a couple of years back on some his his models (not just the Magic Model). The only person I talk to specifically about my own model with is Dr. Gregor Veble of Racing Legends though, sorry
Right.
On top of this what's probably more important is the suspension geometry effects such as Sebastien mentioned. Even if the force centroid was in the middle of the contact patch you would get aligning torque feedback through the steering wheel due to caster angle and any kingpin axis that doesn't intersect the middle of the tire. Kingpin axis is just like caster, but viewed from the front of the car instead of the side.
That's pretty much what I've been doing for a few years now
Runs in real time with no problem at all; see Virtual RC Racing. There are no look up tables or anything like that in there either.Yes. I think I covered that in an earlier post.
Last edited by jtw62074, .
Here's measured data from a real tire:
http://www.performancesimulations.com/files/tire3.JPG
The solid lines are 4 deg slip angle. The one on top marked Fy is the side force (the up/down part is anyway; the left right coordinate is longitudinal) while the Mz is the aligning torque. What they are doing there is locking the tire at 4 deg and 8 deg slip angle, then changing the traction/braking force (slip ratio) in a sweep and then measuring side force and aligning torque. (See how the side force changes with slip ratio? This is what the lateral/longitudinal "force combining" stuff is all about. It's got a big impact on handling and now works a lot better in LFS with the latest patches).
At 0 traction/braking you're looking at a constant turn there (purely slip angle) and you can see where the aligning torque is somewhere around the 65 mark. Once you start adding in traction force the aligning torque increases to a point and then drops off. If you brake, the aligning torque drops and eventually even reverses direction. Keep in mind though that this is at 0 caster. If you ran enough caster these curves would change and might not reverse under braking. I.e., this is not taking into account caster or kingpin axis geometric effects.
Primarily what is probably causing this is that you're changing the vertical load distribution along the length of the contact patch considerably when you add traction/braking, which influences where the contact patch begins to slide and will then move the force centroid.
Under braking, you load up the front of the contact patch and unload the rear, so the sliding point moves forward along with the centroid. You have less aligning torque.
Under acceleration, you load up the rear of the patch, which up to a point could possibly be moving the sliding point rearward along with the force centroid (where the aligning torque is shown increasing). At some point though with enough traction force the slip point and force centroid will move forward and the aligning torque then starts dropping (on the left side of the graph where the Mz lines start going back towards the axis).
So I suppose everybody here is right and wrong at the same time (myself included), depending on the situation
I have no idea if this is modelled in LFS. I usually only drive with spring centering and no FF. But again, this isn't probably going to impact the handling balance very much. It's all really just the feel through your FF that's being effected.
http://www.performancesimulations.com/files/tire3.JPG
The solid lines are 4 deg slip angle. The one on top marked Fy is the side force (the up/down part is anyway; the left right coordinate is longitudinal) while the Mz is the aligning torque. What they are doing there is locking the tire at 4 deg and 8 deg slip angle, then changing the traction/braking force (slip ratio) in a sweep and then measuring side force and aligning torque. (See how the side force changes with slip ratio? This is what the lateral/longitudinal "force combining" stuff is all about. It's got a big impact on handling and now works a lot better in LFS with the latest patches).
At 0 traction/braking you're looking at a constant turn there (purely slip angle) and you can see where the aligning torque is somewhere around the 65 mark. Once you start adding in traction force the aligning torque increases to a point and then drops off. If you brake, the aligning torque drops and eventually even reverses direction. Keep in mind though that this is at 0 caster. If you ran enough caster these curves would change and might not reverse under braking. I.e., this is not taking into account caster or kingpin axis geometric effects.
Primarily what is probably causing this is that you're changing the vertical load distribution along the length of the contact patch considerably when you add traction/braking, which influences where the contact patch begins to slide and will then move the force centroid.
Under braking, you load up the front of the contact patch and unload the rear, so the sliding point moves forward along with the centroid. You have less aligning torque.
Under acceleration, you load up the rear of the patch, which up to a point could possibly be moving the sliding point rearward along with the force centroid (where the aligning torque is shown increasing). At some point though with enough traction force the slip point and force centroid will move forward and the aligning torque then starts dropping (on the left side of the graph where the Mz lines start going back towards the axis).
So I suppose everybody here is right and wrong at the same time (myself included), depending on the situation
I have no idea if this is modelled in LFS. I usually only drive with spring centering and no FF. But again, this isn't probably going to impact the handling balance very much. It's all really just the feel through your FF that's being effected.
Last edited by jtw62074, .
The position of the application of sideforce IS the force centroid, so they aren't moving in relation to each other since they're the same thing.
Anyway, what you're saying is that the force centroid moves with slip ratio changes. Yes, this is true. The point where the tire starts slipping will move forward in the contact patch and the centroid will move forward as well, which would reduce aligning torque. The question is "how much?" My model does this and I suspect LFS's does too, but I'm not yet calculating the force centroid position so don't know how much it might move.
All in all what you've got here from a simulation perspective is just that the force centroid is moving around. In reality it's moving due to camber, slip angle, load, slip ratio, and so on all the time, so the aligning torque is indeed being effected. However, what you're doing is moving this force centroid around solely within that tiny little contact patch. I.e., it's not going to go very far, so the effect on handling is probably negligable. Professional engineering models frequently don't even bother with it. The only important part of that effect is force feedback, so you could really just ignore the aligning torque at the rear wheels completely and nobody would know the difference.
Effectively what you're doing is altering the effective wheelbase and track width dynamically in real time, but I doubt it changes enough to even notice.
Last edited by jtw62074, .
It's the other way around. The tire deformation causes the aligning moment.
Slip angle is just the angle between the direction the tire is pointing versus travelling. I.e., you can project the tire side vector (the axis the tire spins around) onto the ground, then do a dot product with that and the velocity vector of the center of the tire to get slip angle. Aligning torque doesn't "cause" slip angle at all, rather it's the other way around. Slip angle is just the angle.
Aligning torque is caused by slip angle, essentially. In that Pacejka paper earlier in the thread there are some diagrams that show what's happening in the contact patch in the case of pure slip (where slip angle exists, but there's no slip ratio). Rubber enters the contact patch a little bit pulled to the side of the wheel center plane, then is progressively pulled further and further to the side as it travels toward the rear. At some point it then slips back toward the center.
What happens is that the "force centroid," or the effective center of that force, is not in the center of the tire in most cases. The force centroid is like a center of gravity really. All the little forces throughout the contact patch, when added up, are the same as some bigger force acting at one specific spot in the patch. You can see more distortion in the rear of the tire than the front in most cases, so it should be fairly intuitive that the force centroid is usually toward the rear of the tire.
This distance from the center of the tire to the force centroid is called the "pneumatic trail," and since that force is acting behind the center of the tire it tries to twist the tire. Generally it tries to straighten it up, but actually at really large slip angles it can reverse itself (i.e., it makes a torque). The aligning torque is simply this pneumatic trail times the lateral force.
Caster angle then adds an additional distance to that pneumatic trail. I.e., a line through the steering axis intersects the ground at a point. The lateral force acts behind that, so you get an additional torque. The distance from that point to the center of the tire is called the "mechanical trail." So aligning torque becomes (mechanical trail + pneumatic trail) * lateral force.
The aligning torque really doesn't do much to the handling. All it really indicates is that the force centroid is moving a little bit forward/rearward as a function of slip angle. This primarily is just a steering force feedback thing happening.
What about slip ratio and aligning torque?
The simpler answer is that slip ratio produces a forward force in the tire plane. If that force acts in the center of the contact patch along the width of the tire (even if it's toward the rear or front of center), then there would not be any aligning torque contribution due to slip ratio. The force goes straight forward in the tire plane so there's no torque generated.
In reality the situation is not quite so perfect. The force centroid could very well be slightly to the left/right of center (especially with camber) which indeed would give you a little different aligning torque once you change the slip ratio via throttle/brakes. The effect is generally not very big though, and again, for the most part all this is doing is changing the feedback through the steering wheel. Moving the center of force at the tire around in the contact patch a couple of inches isn't going to make a noticable difference in the handling. Although the feel through the steering wheel would be different, and some people appear to judge the handling by the force feedback more than they do the actual balance/understeer/oversteer characteristics of the car.
A little on Pacejka: First, Dr. Pacejka has written a TON of tire models, not just the well known Magic Formula used in Racer and several other sims. I've got a book here published in 1971 that has several other tire models written by Dr. Pacejka, and they're quite advanced. He's been doing tire models for at least 35 years then in that case. There's a reason his Magic Tire model is used in real vehicle dynamics research. It's possible to reproduce real tire test data very accurately with it.
The snag that sim developers run into when trying to implement specifically his Magic Formula is in combining lateral/longitudinal forces. I.e., if you use that formula with say 4 degrees slip angle and no slip ratio, and the constants are chosen correctly to match up with a real tire, the force and aligning moment you get out of the model matches the real tire exactly. If you ran 0 slip angle and 0.05 slip ratio in the same equation with the proper constants for longitudinal slip, again, you'll get the right force.
However, once you start putting in slip angle and slip ratio at the same time, the forces all change. I.e., 4 degrees slip angle with 0 slip ratio produces a different lateral force than 4 deg and 0.05 slip ratio does. If that's not done correctly it impacts the handling in a major way. I think LFS had this problem all along until the latest update, where this now works much better. The result is a car that's easier to drive for sure, which is realistic. Don't let yourselves be fooled into hard=realistic. It just isn't the case at all...
If you get a chance to play the old arcade game Hard Drivin' or Race Drivin', give it a go. That's a vehicle model created by Doug Milliken and associates of a Corvette that uses a tire model with real tire data. I.e., that's a professional engineering model you're driving there that's dead accurate. Is it hard to drive? Not at all compared to a lot of sims, but it sure was harder to drive than Pole Position or any of the arcade games that were out at the time it was released.
You could also try Silicon Motor Speedway, the Nascar simulation. This was done by Doug Milliken too (in fact, they have a Milliken Raceway in his honor that the employees run on occassion). That again uses real tire data and is the same model they use for real research and engineering on real cars.
So if you guys are looking for a benchmark for simulation reality, try those titles and then judge all these other sims based on those.
Aligning torque is caused by slip angle, essentially. In that Pacejka paper earlier in the thread there are some diagrams that show what's happening in the contact patch in the case of pure slip (where slip angle exists, but there's no slip ratio). Rubber enters the contact patch a little bit pulled to the side of the wheel center plane, then is progressively pulled further and further to the side as it travels toward the rear. At some point it then slips back toward the center.
What happens is that the "force centroid," or the effective center of that force, is not in the center of the tire in most cases. The force centroid is like a center of gravity really. All the little forces throughout the contact patch, when added up, are the same as some bigger force acting at one specific spot in the patch. You can see more distortion in the rear of the tire than the front in most cases, so it should be fairly intuitive that the force centroid is usually toward the rear of the tire.
This distance from the center of the tire to the force centroid is called the "pneumatic trail," and since that force is acting behind the center of the tire it tries to twist the tire. Generally it tries to straighten it up, but actually at really large slip angles it can reverse itself (i.e., it makes a torque). The aligning torque is simply this pneumatic trail times the lateral force.
Caster angle then adds an additional distance to that pneumatic trail. I.e., a line through the steering axis intersects the ground at a point. The lateral force acts behind that, so you get an additional torque. The distance from that point to the center of the tire is called the "mechanical trail." So aligning torque becomes (mechanical trail + pneumatic trail) * lateral force.
The aligning torque really doesn't do much to the handling. All it really indicates is that the force centroid is moving a little bit forward/rearward as a function of slip angle. This primarily is just a steering force feedback thing happening.
What about slip ratio and aligning torque?
The simpler answer is that slip ratio produces a forward force in the tire plane. If that force acts in the center of the contact patch along the width of the tire (even if it's toward the rear or front of center), then there would not be any aligning torque contribution due to slip ratio. The force goes straight forward in the tire plane so there's no torque generated.
In reality the situation is not quite so perfect. The force centroid could very well be slightly to the left/right of center (especially with camber) which indeed would give you a little different aligning torque once you change the slip ratio via throttle/brakes. The effect is generally not very big though, and again, for the most part all this is doing is changing the feedback through the steering wheel. Moving the center of force at the tire around in the contact patch a couple of inches isn't going to make a noticable difference in the handling. Although the feel through the steering wheel would be different, and some people appear to judge the handling by the force feedback more than they do the actual balance/understeer/oversteer characteristics of the car.
A little on Pacejka: First, Dr. Pacejka has written a TON of tire models, not just the well known Magic Formula used in Racer and several other sims. I've got a book here published in 1971 that has several other tire models written by Dr. Pacejka, and they're quite advanced. He's been doing tire models for at least 35 years then in that case. There's a reason his Magic Tire model is used in real vehicle dynamics research. It's possible to reproduce real tire test data very accurately with it.
The snag that sim developers run into when trying to implement specifically his Magic Formula is in combining lateral/longitudinal forces. I.e., if you use that formula with say 4 degrees slip angle and no slip ratio, and the constants are chosen correctly to match up with a real tire, the force and aligning moment you get out of the model matches the real tire exactly. If you ran 0 slip angle and 0.05 slip ratio in the same equation with the proper constants for longitudinal slip, again, you'll get the right force.
However, once you start putting in slip angle and slip ratio at the same time, the forces all change. I.e., 4 degrees slip angle with 0 slip ratio produces a different lateral force than 4 deg and 0.05 slip ratio does. If that's not done correctly it impacts the handling in a major way. I think LFS had this problem all along until the latest update, where this now works much better. The result is a car that's easier to drive for sure, which is realistic. Don't let yourselves be fooled into hard=realistic. It just isn't the case at all...
If you get a chance to play the old arcade game Hard Drivin' or Race Drivin', give it a go. That's a vehicle model created by Doug Milliken and associates of a Corvette that uses a tire model with real tire data. I.e., that's a professional engineering model you're driving there that's dead accurate. Is it hard to drive? Not at all compared to a lot of sims, but it sure was harder to drive than Pole Position or any of the arcade games that were out at the time it was released.
You could also try Silicon Motor Speedway, the Nascar simulation. This was done by Doug Milliken too (in fact, they have a Milliken Raceway in his honor that the employees run on occassion). That again uses real tire data and is the same model they use for real research and engineering on real cars.
So if you guys are looking for a benchmark for simulation reality, try those titles and then judge all these other sims based on those.
60 deg FOV does not represent a true view either unless your face is about 1 foot from the monitor, or you've got a REALLY big screen.
How do you people know this? Ever seen F1 tire data?
PhysX news
Hi guys,
Alienware is shipping PhysX processor in their systems now:
http://www.alienware.com/intro_pages/ageia_physx.aspx
Someone told me Dell either bought Alienware or is buying them. I don't know how reliable that info is, but the guy that told me is a real hardware tech head.
Alienware is shipping PhysX processor in their systems now:
http://www.alienware.com/intro_pages/ageia_physx.aspx
Someone told me Dell either bought Alienware or is buying them. I don't know how reliable that info is, but the guy that told me is a real hardware tech head.
My understanding is that the nitrogen is there instead of air in order to eliminate water vapor. If they run air, the humidity that day will skew the hot tire pressures more than nitrogen, which gives more predictable results.
The Indycar series has had cockpit adjustable anti-rollbars for as long as I can remember (well before the IRL/Cart split), both front and rear:
http://www.popularmechanics.co ... 69136.html?page=5&c=y
"The GForce chassis also uses 4-wheel independent suspension with unequal-length control arms, pushrod-actuated coil-shock units and cockpit-adjustable antiroll bars front and rear."
There's a lot of other cool techy type stuff in that link most of you might enjoy. Worth a read
Yes. Surely the car *itself* is not "pressure"
Good post by Becky. I disagree with some of it, and have a little different philosophy on an area or two. All that really matters in the end is that people can set up the car to make it easy for them to drive and be as fast as they can be at the same time. Having said that, a few comments on bits and pieces:
That approach works fine. My philosophy is a bit different in that I base the initial wing setup more on average cornering speed and time spent cornering at a speed where downforce is highly beneficial versus time on high speed straights.
At Blackwood in the BF1, for example, I started out with the default setup (not even the race setup) and then started lowering downforce to take advantage of that great big, long straight. My lap times stayed about the same or got a touch worse. Then it dawned on me that I spend a lot more time in high speed corners than on the straight, so cranked the downforce up to full. The result was that I lost maybe 10-15mph at the end of the straight, but could crank through most of the rest of the turns so much faster I gained a lot of time.
Most people that were a good deal many car lengths behind me at the beginning of the straight pass me going into the last corner, but I pass them by the exit and by the next corner have already more than made up what I lost on the straight. All the next corners are very fast too right up to the start/finish line, so off I go... The speeds on the straights there are so low that the top speed is probably the same, or even a bit less because I can accelerate off the corners harder and brake later.
In the BF1 and maybe most other tracks I'd suggest people just use maximum downforce to start with. Then keep lowering it a bit at a time and see if your lap times drop. Once they stop dropping it's time to leave the wings alone or ramp it back up just a tad for easier car control.
Another reason I like to use higher downforce settings at most places compared to other drivers is that it's usually easier to contend with traffic. When somebody is clearly going to try and overtake me on the inside going into a corner, I'll back off a little bit at the last minute since they're going to have a bad line and very rarely will wind up anywhere near the apex. Then, as they brake too late and go wide, I cut in behind and can clip the apex with early throttle. Having a bit of extra downforce there in combination with the other guy's tendency to botch the corner a little bit really helps, and most of the time I wind up easily in front of them and widening the gap all the way to the next turn. A lot of times this works so well that I have to stab the brakes in order not to hit them on the exit if they kept the inside a bit better than I anticipated.
On high speed corners I use the wings primarily for this. Wing downforce works with speed^2, so of course double your speed and the wings produce four times the impact on under/oversteer as they do in the slow corners, so I use the wings for high speed tuning and use other stuff for low speed. Of course, if there are no wings then...
Not sure what you meant by castor angle effecting wheelbase here. Caster will effect the point of intersection of the steering axis with the ground, which increases along the wheelbase direction (increasing the steering feedback as you pointed out, which is caused by the increase in this "mechanical trail"), but the wheelbase isn't actually effected by this unless castor was adjusted by moving the suspension arms in a pro-dive direction. (Instead of having level arms, you incline them so the fronts are higher than the rears so as the wheels go up and down they also travel a bit forward/backward: Your wheelbase is then changing all the time while driving.) This probably isn't what you're doing in LFS though when you adjust caster.
Increasing caster should generally have the opposite effect you described though, provided the suspension is modelled "right enough," which I suspect is the case in LFS. Caster does primarily two things:
1) It causes the tires to camber when steered. In LFS, peak grip is at 0 dynamic camber, so if you're mid-corner and on the Shift-L display you have anything other than 0 camber, you aren't working the tire to its full potential. However, in LFS you have heat effects here to deal with so need to make a compromise so you don't overheat the tires.
2) It increases weight transfer diagonally across the chassis when steered because one wheel lifts up and the other drops down. In a turn, the inside front is forced down and the outside front raises. This causes increased loading on the inside front and subsequently the outside rear. I.e., you have less weight transfer at the front and more at the rear, similar to what you get if you stiffen the rear/soften the front springs or anti-rollbars, but the amount that you're stiffening/softening things is connected directly to the steering wheel in this case, so it's a tiny bit different.
So... Increasing caster in LFS could very well result in either increased understeer or oversteer (surprise surprise, just as in reality it's all down to how that particular set of tires works). I personally don't muck around with caster in LFS very often unless playing on the skidpad, but if you keep these things in mind perhaps it'll be helpful.
I just use wings for fast corners. Personally I think there are better ways to deal with the slow ones where mechanical grip dominates.
Ok, think I'll skip the rest of my already overly long commentary. It's Saturday night and play time has arrived
That approach works fine. My philosophy is a bit different in that I base the initial wing setup more on average cornering speed and time spent cornering at a speed where downforce is highly beneficial versus time on high speed straights.
At Blackwood in the BF1, for example, I started out with the default setup (not even the race setup) and then started lowering downforce to take advantage of that great big, long straight. My lap times stayed about the same or got a touch worse. Then it dawned on me that I spend a lot more time in high speed corners than on the straight, so cranked the downforce up to full. The result was that I lost maybe 10-15mph at the end of the straight, but could crank through most of the rest of the turns so much faster I gained a lot of time.
Most people that were a good deal many car lengths behind me at the beginning of the straight pass me going into the last corner, but I pass them by the exit and by the next corner have already more than made up what I lost on the straight. All the next corners are very fast too right up to the start/finish line, so off I go... The speeds on the straights there are so low that the top speed is probably the same, or even a bit less because I can accelerate off the corners harder and brake later.
In the BF1 and maybe most other tracks I'd suggest people just use maximum downforce to start with. Then keep lowering it a bit at a time and see if your lap times drop. Once they stop dropping it's time to leave the wings alone or ramp it back up just a tad for easier car control.
Another reason I like to use higher downforce settings at most places compared to other drivers is that it's usually easier to contend with traffic. When somebody is clearly going to try and overtake me on the inside going into a corner, I'll back off a little bit at the last minute since they're going to have a bad line and very rarely will wind up anywhere near the apex. Then, as they brake too late and go wide, I cut in behind and can clip the apex with early throttle. Having a bit of extra downforce there in combination with the other guy's tendency to botch the corner a little bit really helps, and most of the time I wind up easily in front of them and widening the gap all the way to the next turn. A lot of times this works so well that I have to stab the brakes in order not to hit them on the exit if they kept the inside a bit better than I anticipated.
On high speed corners I use the wings primarily for this. Wing downforce works with speed^2, so of course double your speed and the wings produce four times the impact on under/oversteer as they do in the slow corners, so I use the wings for high speed tuning and use other stuff for low speed. Of course, if there are no wings then...
Not sure what you meant by castor angle effecting wheelbase here. Caster will effect the point of intersection of the steering axis with the ground, which increases along the wheelbase direction (increasing the steering feedback as you pointed out, which is caused by the increase in this "mechanical trail"), but the wheelbase isn't actually effected by this unless castor was adjusted by moving the suspension arms in a pro-dive direction. (Instead of having level arms, you incline them so the fronts are higher than the rears so as the wheels go up and down they also travel a bit forward/backward: Your wheelbase is then changing all the time while driving.) This probably isn't what you're doing in LFS though when you adjust caster.
Increasing caster should generally have the opposite effect you described though, provided the suspension is modelled "right enough," which I suspect is the case in LFS. Caster does primarily two things:
1) It causes the tires to camber when steered. In LFS, peak grip is at 0 dynamic camber, so if you're mid-corner and on the Shift-L display you have anything other than 0 camber, you aren't working the tire to its full potential. However, in LFS you have heat effects here to deal with so need to make a compromise so you don't overheat the tires.
2) It increases weight transfer diagonally across the chassis when steered because one wheel lifts up and the other drops down. In a turn, the inside front is forced down and the outside front raises. This causes increased loading on the inside front and subsequently the outside rear. I.e., you have less weight transfer at the front and more at the rear, similar to what you get if you stiffen the rear/soften the front springs or anti-rollbars, but the amount that you're stiffening/softening things is connected directly to the steering wheel in this case, so it's a tiny bit different.
So... Increasing caster in LFS could very well result in either increased understeer or oversteer (surprise surprise, just as in reality it's all down to how that particular set of tires works). I personally don't muck around with caster in LFS very often unless playing on the skidpad, but if you keep these things in mind perhaps it'll be helpful.
I just use wings for fast corners. Personally I think there are better ways to deal with the slow ones where mechanical grip dominates.
Ok, think I'll skip the rest of my already overly long commentary. It's Saturday night and play time has arrived
Last edited by jtw62074, .
I feel quite strongly that this is not the case, actually. After having written several tire models for my own simulator and then driving and really analyzing the reactions on not just the seat of the pants, but also the numerical level, it feels very much to me as though Scawen has made a large leap forward in the model itself, specifically in regards to lateral/longitudinal force combination. I.e., when you're sitting at some slip angle and then change throttle/brake, the lateral force changes too.
Before this patch I really thought it was not right at all and was the cause of all these tire problems. However, to me it really appears to have been drastically improved. I've run my own models with and without these combination errors (took a very long time to figure out a way to do it properly) and the difference is really very similar as to what we see in the change with this new patch.
I haven't tested things too much yet, but after a few minutes playing around in the car park with some of the cars it's pretty obvious this part of the model has been changed, and in a very good way. Good job, Scawen
A lot of the discussion in this thread about handling quirks and so forth I think really can for the most part be attributed to the setup. You can engineer a real car to have lift-off oversteer or not, and so forth. That's what the setup is for and why suspension systems are adjustable. It's to allow you to adjust these under/oversteer tendencies in different situations. It's perfectly possible to build a real car that drives horribly, spins or doesn't spin when you hit the throttle, loses the back end or not on constant radius corners, and so on. That's chassis engineering and a great number of people make their livings at sorting that out with a real physics model (nature!)
Yes, you're right about the high/low speed models. I don't know how it's handled in LFS and personally don't really care as the only time I drive that slow is after I inadvertantly punt someone off the track and wind up in the dirt next to him
Stuff like weight transfer and so on comes straight out of general rigid body dynamics calculations and you really can't get that wrong. As a result of the forces from the springs and so forth the weight transfer will just "happen correctly." I.e., there's no guessing or anything to check there.
I really like the TC, actually. What we really have now is another setup parameter to adjust. For all practical purposes I'm finding I'm adjusting the slip percentage in the way I adjust the power side differential setting in the other cars, and am using the engine braking parameter just like the coast side diff setting.
To me, this doesn't ruin anything having to do with driving skill at all, as raising the traction control slip percentage makes you accelerate faster out of the corners, but makes the car more oversteery in those situations, very much like what you get when you move towards a more locked differential. I think we'll find the fast guys using higher and higher slip percentage here, which is essentially less and less traction control in a way (although not literally).
Don't be afraid to fiddle with that engine braking parameter, folks. Reducing the percentage a lot makes a dramatic change in off-throttle turn in, increasing it a lot, even more so it seems than reducing coast side diff settings in the other cars. In fact, I haven't even touched the diff in the BF1 yet. So far all I've played with are wings and these other two settings.
I'm having a ball though for sure. This patch has really pushed the physics forward dramatically with the fixes in the tire model
To me, this doesn't ruin anything having to do with driving skill at all, as raising the traction control slip percentage makes you accelerate faster out of the corners, but makes the car more oversteery in those situations, very much like what you get when you move towards a more locked differential. I think we'll find the fast guys using higher and higher slip percentage here, which is essentially less and less traction control in a way (although not literally).
Don't be afraid to fiddle with that engine braking parameter, folks. Reducing the percentage a lot makes a dramatic change in off-throttle turn in, increasing it a lot, even more so it seems than reducing coast side diff settings in the other cars. In fact, I haven't even touched the diff in the BF1 yet. So far all I've played with are wings and these other two settings.
I'm having a ball though for sure. This patch has really pushed the physics forward dramatically with the fixes in the tire model
Great post, Tristan At Blackwood in the other cars I usually had time to light a cigarette on the back straight. Now I find in the BF1 I need to hurry just to take a drag of one. Pure heaven, I tell ya, I'm loving this patch! 
Scawen, buddy, I think you've pretty well nailed the combined slip model in your tires now. Congrats! Makes all the difference in the world, doesn't it, guys?
At Blackwood in the other cars I usually had time to light a cigarette on the back straight. Now I find in the BF1 I need to hurry just to take a drag of one. Pure heaven, I tell ya, I'm loving this patch! Scawen, buddy, I think you've pretty well nailed the combined slip model in your tires now. Congrats!
Makes all the difference in the world, doesn't it, guys?The simulated holophonics isn't particularily hot though as it's more or less panning left/right and doing a little filtering to make things sound different high/low/forward/rearward, rather than winding up with a really different sound like you get with the real recordings. The real recordings I too find very impressive, more so than surround sound, but I haven't heard it done with wave files on nearly that level.
Essentially the main component of drag is the difference in pressure between the front and rear of a car. I.e., the pressure on the rear surface of the car is lower than the front, so you get a force trying to slow it down. With two cars running together, that rear car's front pressure is lower than it would otherwise be since it's sitting in the front car's low pressure area, so drag is reduced.
However, the rear car still has relatively high pressure at the front, which most likely creates a high pressure zone that extends to the rear of the front car, which gives it a boost too. End result is that both cars can run faster.
That's my guess anyway Would be fun to model it that way and see what happens though. I don't know if that'd be in the patch though.
However, the rear car still has relatively high pressure at the front, which most likely creates a high pressure zone that extends to the rear of the front car, which gives it a boost too. End result is that both cars can run faster.
That's my guess anyway
Would be fun to model it that way and see what happens though. I don't know if that'd be in the patch though.I thought of that too lol No, these are a totally new design
They're not ready to sell the F1 cars yet. No idea when they will do that as they're still doing prototypes and testing them. These are running grooved, "real" rubber (not foams) that look like real F1 tires. Unfortunately that means they don't have nearly as much grip as the normal 1/8 scale tires do, so the first prototype they ran with standard rear wheel only brakes was apparantly not too well behaved when you wanted to slow down and turn. Those wings don't make nearly as much downforce as the standard Lola diffuser type bodies do, which just compounds the problem. A couple months ago on a visit to the office they had one with four wheel brakes added. That one ran three disc brakes as the rears are done on the layshaft so only need one disc there.
It's a RWD car with pushrod suspension just like the real F1 cars use along with a rear diff. Very trick setup with a long, narrow chassis and all that. A bit longer than the regular 1/8 scale cars, but more narrow of course. They were running a .12 engine in it that was more than enough power for those hard rubber tires. I haven't seen them actually run either car though unfortunately since I was stuck working on VRC in their office when they ran the first prototype for the first time.
It's a RWD car with pushrod suspension just like the real F1 cars use along with a rear diff. Very trick setup with a long, narrow chassis and all that. A bit longer than the regular 1/8 scale cars, but more narrow of course. They were running a .12 engine in it that was more than enough power for those hard rubber tires. I haven't seen them actually run either car though unfortunately since I was stuck working on VRC in their office when they ran the first prototype for the first time.
FGED GREDG RDFGDR GSFDG