Quote from Hyperactive :

I just drew a picture about slip angles... In four wheel slide the car rotates around its center of mass right? Doesn't that mean that the rear slip angle is with (0 steering) always more than at the front? The car isn't going in straight line sideways but it is going sideways around a circle (with little power applied to keep the speed and radius constant)

umm, yes. That's discussed in the rest of my post

As an aside: The drawings look very nice (how did you make those anyway?). The rear slip angles are going in the wrong direction though. The box won't be aligned that way. Instead, the center of the box would be tangent to the path at 0 slip angle rather than the inside rear tire, then rotate further clockwise as slip angle increases.

EDIT: <Slaps self in forehead> Is your car moving counterclockwise by chance?

Why of course it is! You said so right here:

Quote :

Car travels anti-clockwise towards left in the pic.

You have the drawings right, nevermind

Last edited by jtw62074, Sun, 1 Jan 2012 03:14.

I want to add something to that last post. I assumed the rear slip angle was 1 degree more than the front. However, your point starts to become more apparent if we go farther than this and say it's 2 degrees difference instead:

1.0g rear (8 degrees) and 1.0g front (6 degrees). Drift/neutral
0.8g rear (9 degrees) and 0.8g front (7 degrees). Drift/neutral
0.6g rear (10 degrees) and 0.6g front (8 degrees). Drift/neutral

Now the balance has changed from push to drift/neutral and if we go any further (slip angle difference > 2 degrees) the balance would have changed and the yaw moment would have reversed just as you suggested. However, I've got a really tough time believing this is going to happen with slopes that are identical or just a little bit different in practice. The rear tire in this example goes from 0 to 100% in 5 degrees and back down to 0 grip in the next 10 degrees. You'd have to go so far out in the slip angle direction along the rear tire force curve that you find a point that's lower than a point on the front. The slip angle difference to do this on a car as pushy as the GT might be enormous.

Maybe we should try this with some more typical tire data. Unfortunately most real tire data shows very little drop after the peak, if any at all, which kind of illustrates several of my issues including this one all at once...

Last edited by jtw62074, Sun, 1 Jan 2012 02:22.

@Hyperactive:

Just a quick one this time. Been here way too much today already

My thinking is that the rate of drop off would have to be different in order to get this happening where when the steering angle is 0 (almost identical slip angles at all tires then) the balance changes from push to spin. The trouble here with "isn't drop off enough by itself" is that the front tire forces would also be dropping too. Not just the rears. So to use "g" instead of lateral force with a simple tire that rises linearly, peaks at 2 degree points, then drops at constant slope to a ridiculously low value unbelievably quickly:

Tire A:
slip angle
1------------0.2g
2------------0.4g
3------------0.6g
4------------0.8g
5------------1.0g <---peak
6------------1.0g <---peak
7------------0.8g
8------------0.6g
9------------0.4g
10------------0.2g

Obviously as you've said, if the rear tires peak and go still higher in slip angle to say 8 degrees, the lateral g for the rear drops to 0.6g. But so does the front if the steering is 0 and the slip angle is the same. That's why I centered the steering. The balance hasn't changed here. Only the overall lateral acceleration of the whole car has dropped.

The argument can be made (and was in the comments section on my video), that since I straightened the steering the rear slip angles are not really the same. They're a little bit higher. That's fine. If the tires are all the same and the tire force curves were really like this the car could accelerate into the spin. That's why I said if the car was almost a neutral steer car I wouldn't be bothered so much by this. But really, this car is a strong pusher. So the tire above might be our front tire, and the rear tire force limit is higher and might look like this instead:

slip angle
1-------------0.3g
2-------------0.6g
3-------------0.9g
4-------------1.2g
5-------------1.4g <---peak
6-------------1.4g <---peak
7-------------1.2g
8-------------1.0g
9-------------0.8g
10------------0.6g
11------------0.4g

Here the slope of the drop off is the same as the front tire (0.2g per degree) while the initial part rises more quickly and peaks higher as I'm sure you'd agree is obvious from the video.

If we start out a normal turn with the fronts peaked at 5 deg and 1.0g, the rear slip angles are a little over 3 degrees to balance it at 1.0g. We can now kick the back end out with a throttle blip up to 8 degrees and it the car should still return to the original 5 and 3 degrees. This is what happens in the first part of the video.

Ok, now let's kick the car passed the peak and straighten the steering. How much slip angle difference is there between the front and rear tires? 1 degree or so? Not sure off the top of my head, but let's just call it 1 degree. If we slide the rear out to 8 degrees, the fronts are at 7 like this:

1.0g rear (8 degrees) and 0.8g front (7 degrees). Still understeer.

And if we slide the car 1 more degree:

0.8g rear (9 degrees) and 0.6g front (8 degrees). Still understeer.

And another:

0.6g rear (10 degrees) and 0.4g front (9 degrees). Still understeer.

There is in every case here the exact same balance: 0.2g per degree understeer moment, so long as we keep the steering straight and our rear slip angle is 1 degree greater than the front. So I don't think the argument really holds true. Even with a ridiculous drop off on both tires you aren't doing much to the yaw moment passed the peak.

Of course if you countersteered in a slide with these tires and kept the fronts at 5 or 6 degrees, the car would just spin faster, which is one of my other points that I think you agree with already. And of course then as the slope of the drop off increases, steering into the spin becomes more and more likely to be a better way to catch a slide. That does illustrate excessive drop off.

In my video if I had kept the front slip angles at their peaks by countersteering and the car accelerated the spin, it would have shown tire force drop off just like you said. This is why I centered the steering right away in order to show what appeared to be greatly different slopes.

I tried to do this in my sim and it was pretty tough. The front/rear tires had to be quite dramatically different after the peaks. Much more than I was expecting really. It was kind of hard to make it do what the GT did...

Last edited by jtw62074, Sun, 1 Jan 2012 02:07.

Quote from Mattesa :

I'm not quite understanding the issue here, so I'm going to prod at your post a bit of you don't mind:

steady state cornering was pretty strong understeer.

- Okay...

As the rear slip angles increased, the understeer moment decreased slightly, then decreased more rapidly at higher slip angles

- Isn't this expected? As the rear slips more than the front you get less understeer?

and eventually reversed directions. I.e, understeer moment turned into oversteer moment which should not generally happen.

- It seems to make sense though? From steady state you increase speed leading to higher slip in the rears (definition of oversteer?) then eventually gets to a point where the car is yawing into the direction of the turn.

Can you explain what situations and how to replicate what you're talking about in game?

Mattesa, check out the attachment. It's something I made for one of the iRacing forum discussions on this.

This is showing what I believed to be happening with the FGT and HPD cars. Here we see lateral force versus slip angle for the front and rear tires separately. More specifically, these would be yaw moments at the front and rear axles in pure slip which are shaped the same way and have the same features shown here.

In my video I started out blipping the throttle while keeping the steering constant. The throttle blip increased the slip angle (traction circle effect at rear tires) momentarily. With the throttle then released the car straightens back up pretty quickly. This means the peak force at the rear tires is higher than the peak force at the front tires. We could say the rear tires are big fat suckers that stick better than the fronts do.

The trouble was that this reversed at some larger slip angle. If the car was extremely close to neutral I wouldn't have had a big problem with it, but this thing pushed like a tank as can be seen in the video. To reverse course and swap the understeer moment to oversteer moment like that, the fat rear tires would have to have less grip than the fronts do at those larger slip angles. If both the front and rear tires dropped off after the slip angle peaks at about the same rate you wouldn't expect anything but understeer. The car should still straighten up when you release the throttle, or at least slow down in rotation, but it didn't. It was as though the rear and front tire force curves (more specifically the yaw moment curves) crossed over each other and the rears became like little tiny tires that had even less grip than the front tires did, and around you went...

The forums were in an uproar over this and debates on it sprung up everywhere. Half the people said "adjust your FFB" or "you can't feel the g-forces" or "big deal, the car spins out because it's powerful and you're hitting the gas and at low speed you're in first gear and have no traction" or "you just need to adapt to the NTM" and on and on, totally unable to see what we were talking about.

There's something in vehicle dynamics called the Mass Moment Method (MMM for short) where you can plot out the yaw moments on a 2D graph as a function of all combinations of front and rear slip angles. There is a definite characteristic to a car that pushes: As the front and rear slip angles increase to and beyond the peak force values, the yaw moments all converge on a single point or narrow band on the graph somewhere in the understeer moment area. In other words, if the tires peak at 5 degrees and the car is pushing, it will also be pushing at 10 degrees, 15, 45, etc., all the way out to 90 degrees.

More precisely, the yaw acceleration should remain in the push direction, meaning the yaw velocity of the spin should reduce towards zero all by itself regardless of what you're doing with the steering, the way it does in the first part of my video at slip angles just a little bit over the force peaks. I don't have a problem with the yaw acceleration trailing off a bit and changing, but in the video the yaw acceleration not only changes, it completely reverses direction at some larger slip angle. I've never seen an MMM diagram that looked anything like that, regardless of the slip angle.

The only thing I could think of that would cause it was to make the rear force curves drop off more rapidly than the fronts did. At some slip angle they will cross each other and the yaw moment would reverse just like in the video. I tried this in my hobby sim and it worked.

But then think for a minute what this would mean: At some large slip angle, those giant rear tires that created so much more force than the front tires did, creating push at the limit, would lose all that and produce less force than the front tires did, even if the front and rear tires were at exactly the same slip angle. Why would a 335mm tire at 30 degrees slip angle produce less force than a much smaller tire would at that same slip angle? It always seemed rather silly to me and I pointed it out several times. Thankfully they ended up fixing it or at least improving it significantly on both the FGT and HPD in the next patch. Hooray.

Meanwhile many of the people would argue that it's an illusion created by bad force feedback or a lack of g-forces or something along those lines. Doesn't matter. Give them a real car with tire force curves that do that and they'll be complaining about the real car just as much as I complained about the simulated ones.

Last edited by jtw62074, Sun, 1 Jan 2012 00:59.

Quote from Mattesa :

There's one key bit about the final blip that is different... your steering input. You straighten the wheel whereas in the others you keep it pointed into the turn.

Not exactly sure how that might skew things, but induced understeer was something that was thrown around a while back. Could the constant steering input be inducing understeer?

To some extent yes, induced understeer magnifies the effect. However, this is really further evidence that the force curves drop off too much after the peak rather than the opposite. Induced understeer is a geometric effect (tire lateral force vector pointing more rearwards and less sideways), but is significantly magnified by any drop off in force occurring in this region of the tire force curve at slip angles beyond the force peak. No force drop off means very little induced understeer. In that case countersteering to correct a slide will do what it's supposed to: Slow down the yaw rotation rather than speed it up. This goes hand in hand with steering into a spin in order to save it.

However, I'd still argue against induced understeer being the cause, rather than something that magnifies it and thus might overshadow it, for another reason: As far as I was able to tell, this was happening with all four tires pointed straight ahead at any slip angle somewhere between the peak and around double the number of degrees passed it. I.e., with all four wheels pointing forward (0 steering), and peak lateral force coming in at (just making this number up) 7 degrees, the car was understeer at 7-12 degrees and oversteer at anything over that. The trouble was, the further the car rotated the faster it accelerated into a spin. This makes catching a slide ridiculously more difficult than it is in reality.

(By the way, I'm just making up those slip angles to illustrate. I don't know what the real numbers were.)

This stuff is much easier to see when you make a sim, or have one handy like rFactor or Racer or something where you can play with the tires yourself. I'd encourage anyone interested in this to try making tires that drop off very quickly after the peaks and see what this does to the car. As you steer into a spin the car straightens up. As you countersteer you accelerate the spin. It's the opposite of what happens in reality and is the main reason why some sims are so hard to catch slides in. People can argue about lack of g-forces or bad force feedback all day long, but they're missing this key point: If the tires do this the cars will be just that much harder to catch on top of the missing g-forces and bad FFB. In many cases, significantly so.

Live For Speed doesn't have this problem.

Last edited by jtw62074, Sat, 31 Dec 2011 22:04.

Just after writing that last post I think the "release brake and spin" stuff finally crystalized in my head. It may be that this is much simpler than what I suggested in the last post. I'll try to explain. What we're going to see here is that this can happen with no load sensitivity at all. Load sensitivity would alter it, but in the complete absence of load sensitivity this "release brake and spin" stuff can still happen.

What we'll do is look at a car that is cornering at two different states seperately. First, a car that's cornering without any braking applied at all. Let's call this "pure cornering" from here on out. The second case would be a car that's cornering and braking at the same time, which we'll call "combined cornering" since it's doing a combination of two things at once (braking and cornering). Cool? Okeedokee then.

In the combined cornering case the car has forward weight transfer. In the pure cornering case it does not. So let's take a look at a car in both situations. I'm using a little program I wrote to spit out tire loads given lateral (cornering) and longitudinal (braking) accelerations. The weight of the car is the same as the real skip barber car, but I'm using 50/50 weight distribution because this translates directly into yaw moments so we can see push/spin at the limit without doing more calculations. Also I'm using 50% front total lateral load transfer which is probably too low for a Skip Barber car. The fundamental behavior is what we're trying to look at here, not necessarily the specifics of the Skip Barber F2000. Here are the specs I'm using:

Weight 1500 lbs
Track width 61 inches
center of gravity height 12 inches
front/rear weight distribution 50%/50%

Ok, first the pure cornering case. I'll keep the accelerations somewhat lower than the real car can probably do so we don't fall into the trap of thinking this is something that only happens when we're at the limit of traction. We'll start by cornering in a left turn at 1g which lets us skip a calculation or two and keep things simple. In the data below, the wheel loads are laid out like this:

Front left tire-----Front right tire
Rear left tire-----Rear right tire

Cool? Ok then. Here's the pure cornering case:

Pure cornering:
Lateral acceleration : 1g
Longitudinal acceleration: 0g
wheel loads:
227-----523
227-----523

Ok, we can treat this for simplicity as though there are two torques acting here. One from the front axle and the other from the rear. The front axle is trying to twist the car to the left which we'll call positive "yaw torque," and the rear is trying to twist it back the other way which we'll call negative "yaw torque." If we add the wheel loads of the front two tires together, then the rear two tires together, in our simplified case we can just treat these for the sake of this example as the yaw torques themselves. So what are the yaw torques?

yaw torque front axle
+750
yaw torque rear axle
-750

The total yaw torque on the car is just 0. (+750 - 750 = 0.) This means the car is rotating at a constant velocity in our corner. So it's probably just zooming around the turn normally and might be pushing or neutral, but at least it's not accelerating into a spin. It's just your standard normal turn.

Ok, now for case two. Here we'll add 0.5g braking:

Combined cornering:
Lateral acceleration: 1g
Longitudinal acceleration: -0.5g
276-----571
179-----474

This gives us yaw torques:

yaw torque front axle
+847
yaw torque rear axle
-650

Total yaw torque (847-650) = +197. This is an oversteer moment now so the slip angle is going to increase from here, perhaps even spin. This is just your standard forward weight transfer under braking trying to spin the car around that you might normally expect. More weight on the front tires = higher yaw moment in the oversteer direction.

So where are we now? The pure cornering car is neutral while the combined braking/cornering car is oversteer. As I went over in the previous post, in reality with our braking we are reducing the lateral forces. In the case of the Skippy this changes the combined cornering scenario by reducing the front lateral forces more than the rears by enough to end up with understeer instead of oversteer (negative yaw moment instead of positive).

In this case we might have something like the following. So far, for simplicity we assumed the wheel loads were equal to the tire forces. Under actual braking we'll end up changing the lateral forces, so instead of 203/645/106/547 tire lateral forces we might wind up reducing the front lateral forces to around 60% of what they would have been and the rears to 90%, winding up with something like this:

Combined cornering:
Lateral acceleration: 0.7g
Longitudinal acceleration: -0.5g

tire forces
166-----342
161-----426
yaw torque front axle
+508
yaw torque rear axle
-587

Total yaw torque (508-587) = -79

This isn't really right because these numbers would change the lateral acceleration, which would change the wheel loads, but the point is that there is enough braking here to reduce the front lateral forces so far that we end up with understeer under braking and cornering because of the effect of the brake bias on the lateral forces of the tires. Here the understeer or push is shown by the -79 total yaw torque. So even though the numbers here are not really right, the principle is still the same: Enough forward brake bias will give you understeer. The front tires do not actually have to lock to create rather dramatic push, as a couple of you found out on the real Skip Barber car.

We now have three states instead of two:

1) Pure cornering (no brakes)
2) Combined cornering and braking without the brakes reducing the lateral forces at the tires, resulting in an oversteer moment
3) Combined cornering and braking with the brakes reducing the lateral forces at the tires, resulting in an understeer moment

Here's the kicker and where the "lift off the brakes and spin" moment happens: When you are braking and cornering you are really in state #3 where the lateral forces are reduced enough at the front in relation to the rear to make the car push instead of spin. However, at the instant you release the brakes, the tire loads are still in state #2. The tire forces then jump to that as well.

You jump from state 3 with the brakes applied to (almost) state 2 when we instantly release the brakes. I.e., the weight is still transfered forward even though the brakes have been released and the longitudinal acceleration has returned to 0 because the springs are still compressed due to the pitch of the car. The orientation of the body has not yet changed to pure cornering. The nose is still down.

So we get a quick burst of oversteer when we release the brakes. As the nose starts rising back up we are transitioning from state 2 back to state 1 where there is understeer again.

The shock absorber settings will influence how quickly these state transitions happen, but right now I'm thinking they really aren't the cause. The real trouble to me at this point seems to be lying in the brake bias itself. If state 2 was neutral and the brake bias of state 3 was adjusted in a way to also be neutral, you would transition from braking/cornering to pure cornering when releasing the brakes without changing the yaw moment or at least not letting it ever go positive. In other words, the tail wouldn't kick out and it wouldn't matter much that you released the brakes.

What's interesting about this to me is, if my thinking is right here, that this basic thing should happen independently of whether or not there is load sensitivity in the tires, and that this shows up even if we completely neglect the shocks. It's possible that the shocks might make this situation worse or better than this, however, but the underlying thing here seems to me to be more about brake bias than anything else.

What about releasing the brakes quickly versus slowly? As we saw before, releasing the brakes instantly takes us from state 3 (push) to state 2 (spin). However, if we do it a little bit more slowly the oversteer moment will not jump immediately to +197. It'll be lower than this because while we're transitioning from state 3 toward state 2 we are keeping the front tire lateral forces lower than the rears through the brakes, like in state 3 but not quite as much.

If you released the brakes slowly enough you would never hit state 2 where you have full forward weight transfer and no brakes. You'd slowly transition from state 3 (mild understeer) to state 1 (neutral) and all the inbetween states would be somewhere between mild understeer and neutral. The car wouldn't spin. It looks to me like this might be where the fast or slow release of the brakes might be coming into play. You have to avoid jumping too close to state 2 and try to go from state 3 to state 1 instead. Either that or fiddle with brake bias or use gas and brake at the same time to dynamically alter the brake bias throughout all this.

I'm really glad you asked about this. I never gave it this much thought before, but this seems to be the situation as far as I can tell. It also seems that if this happens in a sim, it isn't necessarily a matter of "bad physics" or a bad tire model, but rather a case of "this car and its tires need a bit more attention in this area and could be improved"... It seems to me that the iRacing car goes a bit overboard with this, but the fundamental behavior isn't necessarily wrong. Some small adjustments to the tires on the car could probably get it to be closer to the real car in this area.

Last edited by jtw62074, Sun, 1 Jan 2012 00:41.

Ok, back to comment a little on releasing the brake and getting oversteer finally. I didn't do any testing in my hobby sim to look more closely at this, so am somewhat speculating.

What comes to mind primarily is that this is something that ought to be improved with brake bias. Madcat, you talked about how using heavy braking was like locking the tires without actually locking them. In other words, the lateral force decreases on the front tires as you increase braking. This happens with almost any decent amount of braking, except very light braking where the reverse is usually true. So for the sake of discussion, let's call the area where the lateral force drops with increased braking "moderate to heavy braking." Sound good? Ok..

You don't need to lock a tire for this to happen, or even be operating at the limit of the traction circle/ellipse to see this reduction in lateral force come in to play as braking is increased. The same goes for the rear tires of course. One thing that happens under moderate to heavy braking and cornering is you're losing lateral force at both the front and the rear tires. I.e., the yaw moment contribution (the torque that twists the car) decreases on both. If you get them to drop the same amount so the yaw moment doesn't change as braking is increased, the car should drive very easily into the turn with no surprises regardless of how much braking you're using. That's a very well built car though. Most aren't that good. This is where stability control systems shine.

On top of this the forward weight transfer is influencing the forces too which complicates the picture quite a bit. With one wheelbase to center of gravity height ratio you might get understeer, with another you might get oversteer. So it's not easy to point to a single cause that applies to the case of every vehicle (real or simulated) that displays the seriously annoying behavior the iRacing Skippy does in this situation.

Anyway, if the front lateral force drops more than the rear (more precisely, if the yaw moment contribution of this lateral force goes more toward 0 than it does at the rear), the car will understeer under braking, which matches Madcat's description of the real Skip Barber car's behavior.

The opposite is then true of course if the braking is moved more toward the rear. The rear could lose lateral force more quickly than the front. In that case as you increase braking you get less understeer, and if you go far enough you're effectively using an e-brake to spin the car like Shotglass described. So at first thought it sounds to me like with the Skip Barber car you could improve this with a brake bias adjustment. The trouble then though is that you might be making a big compromise in straight line braking where ideally you might want all four tires to peak simultaneously. So there's a trade off to be made in this if ABS or stability control isn't allowed which theoretically can overcome this very problem.

What about releasing braking? If we start with the first example where the front lateral force was lowered more than the rears under moderate to heavy braking by the forward brake bias, then it would follow that when you release the brake you'd get all of that lateral force back and the front end would tuck in more again.

However, this explanation doesn't adequately address the big spins you tend to get in the iRacing Skippy. When you release the brake, the car doesn't just return to the normal amount of "no throttle and no brake" steering. Instead it goes dramatically toward oversteer. I tend to think the difference there might be in the damper rates, something along the lines of what Shotglass was suggesting. This area of vehicle control needs some fairly heavy analysis because so many things are at play, so it's tough to make a generalized "here's why it happens" statement that points to a single cause. Some things have easier answers than others...

Maybe I can give the Skippy another drive and pay more attention to this, maybe look at telemetry a bit, despite how much I dislike this car since the last time I drove it.

As to whether or not it's "because of the rear weight bias," the best answer is probably a not very helpful "yes and no." The rear weight bias largely determines what brake bias you need to use to begin with. When you then match a set of tires to that car you'll get either understeer or oversteer under braking while cornering. It's really a matter of design choice (and success in making it do what you meant it do when you designed it!) A real car can go either way. So it's a combination of all of these things at play here.

If I had to pick one thing though, my gut says it's more about the brake bias than anything else. People that are fast in the car are using brake and gas at the same time. The only reason to do this that I can think of is so you have a dynamic brake bias. Under braking by itself you have more rearward bias that, in the iRacing Skip Barber car, overcomes the push you get in the real car under moderate to heavy braking while cornering, but this is too much rear bias for straight line braking, so in that case you use a healthy does of throttle to shift it forward. Some people are good enough at this to adjust the brake bias with the throttle all the way from the straight right up to the apex.

A way to really find out what's happening is to plot out the yaw moment contributions from not just all four tire forces, but also their lateral and longitudinal components. So you'd be looking at 8 different plots really to try and analyze what it's doing (easier said than done). If I worked for iRacing and my job was to engineer these cars, I'd be begging Dave K. or somebody to plot this data out live so I can see what's happening while driving. I do this in VRC Pro. Then for example you can point at exactly how much the front right tire's braking force (longitudinal force) is contributing to understeer, and how much the lateral component is doing just the opposite. Do that for all four tires and see how they change during that little transient where you release the brakes and it should give a better picture of what's happening. I wish it were simpler than that, but in this case it's probably not.

I've often wondered what the real Skippy does, so I'm really happy that you got into this discussion and explained what it feels like in the real car, Madcat. Thank you.

Last edited by jtw62074, Sat, 31 Dec 2011 19:14.

Quote from Shotglass :

well it does look a bit like what the car would do if youd pull the handbrake so the effect could theoretically come from way too strong engine braking

If it was engine braking, the behavior would manifest itself right away at small slip angles rather than just large ones. In the first part of the video where I'm blipping and releasing the throttle, the car straightens up when the throttle is released (understeer yaw moment). The trouble is that this fundamental behavior reversed course once the slip angle grew enough. The understeer moment decreased, passed through 0, and then changed sign.

If the car would accelerate into a spin like that at all slip angles rather than just large ones, engine braking indeed would be one thing to look at. It seemed there was a cut off point or critical angle where the behavior changed. I plotted out telemetry showing this happening too where the angular velocity actually doubled at some point from the beginning of hitting this "critical angle" until it started slowing down enough for the car to nearly stop. The trouble is the tires would twist the car to the left to straighten it, but then actually reverse and twist it to the right.

The first video of the car doing the quick 180 shows this too, but it's not obvious unless you're watching the yaw acceleration closely. There's a period there where the throttle is released and the car not only keeps on spinning (that's not a problem), but the spin briefly gets faster. The vid is so short though and it looks so much like a regular half donut it's easy to miss, so I made the other one to show it more clearly.

Last edited by jtw62074, Sat, 31 Dec 2011 18:14.

No, I didn't. It shouldn't really matter.

iRacing pretty much fixed it on this car by adjusting the tires after this in the next patch.

I'll try to explain it in more detail later. Here's the video illustrating it:

http://www.youtube.com/watch?v ... DskLoU9NMCUmLAQOK5xmabvji

I don't have a problem with this happening in the rain on a near neutral car, but in the dry this is a no-no I'm afraid.

Very interesting. Thanks for sharing.

I didn't mean to suggest people can't sense movement and that it's not a factor at all, just that there have been lots of discussions over the years I could point to where it's rather overblown imo. For instance, seeing yaw moment reversal in a sim does not require seat of the pants feel. It can be spotted visually, yet in the discussions on this the argument that 'you can't feel g-forces so you don't really know' was used. There are plenty of examples of this type of thing.

Not trying to argue, just clarifying what I was getting at a bit better.

Quote from Postman Pat :

But there's the other thing - how difficult would it be in RL to control a car on the limit without your inner ear and other physical sensations telling you when it's starting to yaw etc? That does make it difficult to compare 'difficulty'.

I think the "missing g-force" feel factor is not nearly as important as people generally seem to suggest. In my work on VRC Pro with top level racers (even many who are not so top level) in the world, the amount of feel they describe in the car is surprising. When analyzing some of their setups in telemetry during testing recently with the new 1:12 scale electric car, they were adjusting things by one degree slip angle or so. I saw three out of four testers set up their cars to turn at one slip angle within +/-0.5 degrees of each other, saying that 1 degree less than that was "too pushy," while another guy was a little bit outside this range. In our simulation it makes an especially interesting case because the inputs they have really are identical to the real thing. No FFB, they use the same radio as they do in real racing, and there's no g-forces to be felt in either case.

That's just one quick example, but this is all purely visual feedback they're using just as we use in big car sims. So personally I think this missing feel stuff is generally much overrated, especially with experienced sim racers. When slip angles in a big car sim are tightened up only a degree or so, many people can tell right away something was changed.

Last edited by jtw62074, Fri, 30 Dec 2011 16:38.

Quote from atledreier :

I almost never drove a rear wheel drive car, but testdrove my friend's stock RX-7 and was drifting it inside of 20 minutes. Since then I've owned an MX-5, and if my MX-5 was as lethal as the iRacing one I'd be dead several times over.

My MX-5 gets snappier with the R888 tires on, but still easily driftable and 'incidents' are fun, not lethal.

Great to hear. Thanks for sharing.

This is the same sentiment I see echoed over and over from real drivers (including the friend in the Donkervoort) and not just in iRacing. Harder = more realistic is nonsense a lot of the time. That was true when we went from Pole Position type games to things like Grand Prix Legends, but not so much these days. A great deal of the engineering involved in tire and vehicle design is on aspects of control-ability. You don't want vehicle responses to be outside of certain ranges in certain situations. They need to be engineered to handle in a way that drivers feel comfortable with. If you have to baby the thing around the track just to keep it pointing forwards, it's time to take it back to the garage and call in the tire engineers to figure out how to improve it.

Last edited by jtw62074, Fri, 30 Dec 2011 09:42.

Quote from Hyperactive :

To me it seems iracing have the knowledge about tires and would know how to make them better but they also still have this ideology that driving race cars fast or getting over the limit is really really difficult. A bit like the gtr game developers. They had the necessary data but they did not want to believe it and adjusted the numbers to get the difficulty up where they thought it should be. I think the ideology that driving race cars is difficult sits very firmly still in the minds of the sim developers and while there are people who are not afraid to put the real data into the sim and believe it there are still many who adjust even very good data to make it harder just because "that's the way it should be".

I agree and have frequently thought the same thing. Before I made my video I played around with tires in my hobby sim to see what it would take to make a car do what the FGT and HPD were doing at the time. It turned out to be quite a bit more difficult than I thought. I was surprised, and yes, "difficult to make it do that" would be the right phrase to use here.

By the time I'd done it and made the car worse than the FGT was by intentionally making a lot more drop off at the rear tires than the fronts with the sole purpose in mind of getting the car to accelerate the spin after a certain slip angle, I realized that I'd almost have to do it on purpose and spend a fair bit of time tuning it to get the "right amount" of acceleration going into the spin. I came away thinking there was at least some chance this was done intentionally because so many people expect cars to do that. That could be wrong, but it was really harder to do than I thought it would be. I can't see myself accidentally making a car that pushes as much as the FGT did exhibit that behavior. I'd probably have to spend hours to make it work that way.

I also agree with you about the Corvette: I played with it for a little while (on the OTM) and dropped it pretty quickly. That one was a disappointment. I tried it very briefly (maybe a lap or two) with the NTM after a very long period of not touching the car and to me it seemed to be better. I'm not too sure about that car though. Need to play with it more.

Brake release oversteer: Haven't forgotten about this one yet. Still need to give it some thought and maybe play with it in my hobby sim to comment.

Last edited by jtw62074, Fri, 30 Dec 2011 09:25.

Quote from BlueFlame :

To be honest, I think the grass is iracings biggest flaw.

I agree the grass feels funny. It's similar in a way to the behavior I showed in my video where the rear might have more grip than the front until you get in the grass where the situation reverses. If a car is dramatically pushing on asphalt, why would it not keep doing that in the grass? I don't really know how that should work, but agree with you that something about that feels funny. I care a lot more about onroad behavior than what happens in the grass though so don't make much fuss over it.

Last edited by jtw62074, Fri, 30 Dec 2011 09:39.

Pat,

You probably are seeing something a little funny then. I tend to notice these oddities in a little different way because I'm looking at different things, probably. The point of rotation of the vehicle doesn't enter my mind. That doesn't mean it isn't wrong, I just might be spotting it as an odd change in yaw velocity or something like that. A "rotation axis goof" might be a simultaneous symptom of the underlying cause of that, but it's not a programming thing where they got the basic physics calculations wrong. It's all in the tires.

One thing that might be at play here, and this is something that bothers me about a lot of the iRacing cars with an exception or two, is that they seem to have largely gone the route of rFactor and friends with regards to over the limit tire force behavior. I.e., how forces change beyond the peak lateral force slip angle. Most of the cars drive like there's a great deal of drop off. Not nearly as much as rFactor and it's brothers had when they came out, with the exception of the street tire cars in GTL which to me were just marvelous, but still too much. Thanks to the telemetry we can now see pretty accurately how much there really is. In the cars I skidpad tested with telemetry, it's somewhere between LFS and rFactor in this regard.

This drop off in force after the peak can add significantly to what you're describing, especially if the balance in drop off between the front and rear tires isn't matched up well. You end up with behaviors that feel strange, like a car that understeers strongly up to the limit, then a few degrees beyond that becomes neutral steer ("drift"). At that point countersteering doesn't really do anything so it suddenly feels like a different car. It doesn't blend into the drift and feel natural, or respond to small countersteer and throttle inputs. You have to countersteer further and further while nothing happens, then steer a bit more and wham, it starts to react. The higher the stiffnesses the quicker it reacts. At 5 degrees slip angle you're fine, but at 5.2 you're just going along for the ride. Sound like the MX5 or any other cars to you?

On top of this, too much drop off makes the situation much worse because when you first begin countersteering in a slide, the car not only doesn't start to slow down its rotation as you'd expect it to, it speeds up and you just spin out even faster than if you had done nothing at all. So you wind up with this tiny little window of steering that you have to snap the wheel to as fast as you can in order to catch a slide. Too little and you accelerate the spin. Too much and you spin the opposite direction.

Want a quick way to check if there's a lot of drop off or not? Next time you slide a car, steer into the spin instead of out of it. If the car straightens up right away it's all because you reduced the front lateral force a bunch by increasing slip angle. The more you feel that, the more difficult the car is to catch probably. There's a lot that I like about iRacing so I don't want to sound too negative about it, but one of the things I don't like on some of the iRacing cars (the high end slick cars primarily) is that it's much easier to save a spin by steering into the turn instead of out of it. Countersteering just makes things worse on many of the cars. In the 842,305,201 in car videos I've watched, I have never seen anyone do this in a real car. Why not? You'd think somebody would have figured this out by now. It's a much safer way to catch a slide, apparently.

Live For Speed got it very close (if not perfect) and does this very well. When you overstep the bounds and countersteer a little bit the way you would in a real car, the yaw velocity slows down as you'd expect rather than the exact opposite. There isn't a tiny little window of acceptable steering angles that work to catch a slide. As a result, Live For Speed is much easier to drift than other sims are, and it feels (to me at least) much more natural to dance around the limit with. There isn't some switch that's on at 6 degrees and off at 6.001 degrees. Maybe some people say it's too easy, but I think they're just comparing it to other sims where it's much harder to do. I see this easier sliding and ability to drift the car in a natural feeling way as a plus, and a sign that LFS handles this area better than even iRacing does with one of my heroes, Dave Kaemmer, at the helm.

When I ask real drivers about it the majority seem to say that drifting is too hard in their favorite sim and should be much easier. If LFS is "too easy" to drift, I'd say "good, it should be a lot easier than it is in <insert sim name here>." Rock on, Live For Speed.

People need to pay attention to what exactly the comparison is being made to on that. Another sim or experience from real driving?

Anyway, point being that this excessive drop off is probably a large part of the oddness you're seeing with the Nascar vehicles (among others). I haven't spent much time in those cars since the NTM came out so can't fairly comment on how it is now. Next time I do I'll remember to check and post something here again.

To be a little fair and balanced, iRacing's SK Modified is remarkably better over the limit than many of the other cars.

Last edited by jtw62074, Fri, 30 Dec 2011 09:35.

I'm one of the original two authors, so yes, we've spoken here at the LFS forums a few times

If I could discuss the sales numbers that came in just from beta testing (we had quite a few spend $200 or more the first week that are still around), and how many of those testers are still with us as normal customers, you might be surprised at the reality of what happens here. We've done this two or three different ways over the years so have seen what happens in our product both with free beta testing and paid beta testing. In this last batch we had around 300 beta testers iirc, all of whom (with the exception of some griping from two or three) happily forked over their hard earned cash to get the product a few months before anyone else did. All we needed was a handful of thorough testers out of that group, and we got that.

Anyway, as I've said before in this thread a couple times, the demo is indeed free now.

Average gamers: I understand your point about this and at times tend to agree, but one important fact about this product is that very few people that are not in the RC racing hobby find it remotely interesting anyway. There's a big learning curve in driving an RC car for the first time from outside the car's perspective. Helping people overcome that is really how the idea of doing all this came about in the first place back in '95. VRC was originally intended to be a learning tool for people thinking about getting into real RC racing. It was intended partly to boost sales of real RC cars and expand that hobby. Eventually VRC took on a life of its own and became a product with sales value in its own right. The owner sold his real RC car company after founding/running it for 30 years, and now does nothing but VRC. Anyway, if you hand this to a kid or somebody with no RC experience, regardless of how easy the physics are made to be, they usually give up quickly unless there's a chase view. The "steer left to go right" when the car is coming toward you takes some getting used to and eliminates most gamers from our market right away.

So this isn't a typical car simulator that maybe 30% of the gaming population will find interesting. In addition, the majority of our customers drive RC cars in real life, regardless of the price we set. We've tried multiple pricing schemes over the last seven years (we've been around longer than LFS; The first version before I got involved was in '97). To get much out of it you need an RC-style controller, something very few people have, even to run the free demo and get an idea what the full version would be like. It'd be like trying to sell LFS or any other serious car simulator to the majority of people out there that don't have a wheel. Regardless, I pushed hard to get us into E3 and into some more typical game marketing channels, but the boss man wasn't having it.

Regarding price: Finding the optimum price point is tricky on any product as I'm sure you know, and we've tried several basic approaches and pricing schemes here. Originally back in 2004 we released the first version with a free demo and the option to pay as little as $7 for something that had at least one extra track aside from the free content that came with the demo. So people could spend nothing, $7, or go on up to $200 or more if they wanted. The highest sales revenues did not come from the $7 group...

Perhaps a year or two later we changed that so the minimum you could spend (aside from the free demo) was a lot higher (I want to say $50 or $60, but don't recall exactly). Sales revenues jumped substantially at the much higher price. If you stopped by our forums you might be surprised at the different attitude most of our customers seem to take on pricing. You hear a lot of "big deal, I spend way more than this on my real racing" and "this is saving me money on my hobby" kinds of comments, something I've never seen in any other simulator forum.

I tend to push for lower pricing anyway much as you suggest, so don't get me wrong. I'm not really in disagreement, just pointing out that there are some differences with our product and we've tried a lot of different things over the years.

Quote :

"If you are taking money then you do not have testers, you have customers.'

We might not have the general high quality testing that full time, paid testers might provide. Does LFS have this? Is it needed? If Scawen posted something asking for people to test some new content for S3, there would be a line of people out the door waiting to get in. Call them what you want, but if they test and find things you missed or would rather not spend time on, they're plenty useful.

On creating another not-so-serious version for the masses: We've kicked this idea around too. Somehow we always manage to find other things to do first. In all seriousness, doing that could be a massive project of its own. I'm also afraid it would be bad for the 'serious sim' image. Imagine if the LFS guys released an arcade version of LFS. What would that do to the mainstream LFS? I'm not sure how well you can market your product as a serious simulator when you have this other version floating out there. If the Need For Speed creators released a "Need For Speed: The Realistic Simulator version" that was every bit as hard core as LFS, with vehicle dynamics engineered by Doug Milliken himself, how many people here would take that at all seriously?

Anyway, we're working on offroad (buggies/trucks/etc). I'm hoping that will tap us into the more casual gamer market without having to give up the serious sim approach and turn it into an arcade game. I have no interest in doing that.

Last edited by jtw62074, Fri, 30 Dec 2011 04:39.

Pat,

The apparent axis of rotation you seem to be refering to is highly subject to the camera's focal point. I've played with this a little bit and (to my eyes anyway) the car will look like it's rotating around whatever point the camera is focused on. Focusing the camera on the rear bumper makes it look very different than if it's on the front or somewhere else. So what I'd be looking for here are the magnitudes of the yaw velocity and yaw acceleration to spot a problem rather than trying to figure out what point the car is rotating around. I'm not even sure how exactly somebody would define a yaw axis off the top of my head really, with both translation and rotation happening at the same time.

When I suspect something is up I crack open the iRacing telemetry and usually find that what I'm looking for is really happening. I wrote a lot of posts in the iRacing forums showing things like yaw moment reversal at high slip angles that I'd been complaining about for a long time, but couldn't clearly illustrate to anybody until the telemetry stuff came out, regardless of how blatantly obvious it was to me after one minute on the skidpad in this car. This is what was illustrated in my video earlier, along with the other video of the car doing a quick 180 that doesn't look unusual to most people. The same problem can be seen there too, but is tougher to spot. Most people miss it and say there's nothing wrong, but they aren't looking closely at the yaw acceleration and velocity which can both can be seen to speed up considerably after the throttle is released and the slip angle grows a fair bit. The yaw velocity roughly doubled in situations like this which was highly questionable and is what people felt was wrong with this car. All most people see is the car pointing this way, then that way, over so much time and that's about it. Sure enough, the very first test with telemetry confirmed exactly what I felt was happening all along. The next patch it was fixed on the GT and HPD.

Unfortunately they won't show slip angles in the telemetry. I don't blame them one bit really. I probably wouldn't show them either.

Moment of inertia: In VRC Pro we use data straight from the manufacturer's Pro-Engineer design files for inertia moments, so in our case it's integrated from the mass properties density, volume, and location of each part, right down to every little screw in the whole car (these get pretty small in RC cars). I don't calculate this myself. It comes out of the engineer's software. They send me giant readouts with inertia properties and I plug the relevant values into my model. The car itself is only part of the picture though. I also get all the drivetrain parts including all the rotating shafts and gears, tires/wheels, and so on. I've done it this way for ten or eleven years now.

I doubt most sims get that good of data, but the idea is to try and get it from the manufacturer if you can. The engineers are fairly likely to have good computed data on it. If that's not possible to get, there's a database online somewhere that has something like 100 or 200 cars and trucks in it that were measured and/or compiled by the NHTSA. If I'm not mistaken, this is done using a "swing test" or something similar, where the principle moments of inertia around the yaw/pitch/roll axes are measured directly from the real car, like weight or anything else would be. When I play around with regular sized cars in my hobby sim, I refer to that database a lot and just pick a car that's close to it, then make a semi-educated guess at massaging the numbers a bit. I think that paper has been posted here at the LFS forums many times over the years. I've got it here on my drive so will look up the title if you're curious. It's a free paper you'll find quickly.

Another option is to try and estimate it from the wheelbase, mass, and other properties of the vehicle. One approach is to estimate the inertia moments with boxes of different sizes and masses positioned in various locations. Maybe one for the engine, another for the chassis, etc.. There's a gentlemen by the name of Brian Wiegand, a retired Northrup Grumman "Senior Weights Engineer & Mass Properties Handling Specialist" (that's the title in one of his papers, "The Mystery of Automotive POI Values"), that has done a lot of work in this area. Funnily enough, he contacted me recently about an article I wrote online asking for attribution information for a research paper he's working on, and we got to discussing this very topic. If you're curious you might see if you can find the paper online somewhere. It's something the SAWE charges for though so I'm not sure if you'll find a free copy around. I wasn't able to so had to ask him directly.

Another paper of his that he pointed me to is SAWE #3490 Automotive Mass Properties Estimation which deals with this very thing. This is what you might try to do if you don't have measured data from a swing test of the entire vehicle or really good CAD data like I use in VRC Pro.

I'll try to address the rest of your post in another reply later. Just wanted to touch on the rotation axis and moment of inertia stuff while it was on my mind.

Last edited by jtw62074, Thu, 29 Dec 2011 15:37.

Quote from Postman Pat :

Todd. Sort of related, but I'd like to ask you about some issues, since you have knowledge on this stuff.

IMO, slow speed spins still happen in the MX5 and Skip. It feels like you countersteer and balance the throttle but there's no discernible effect, you countersteer a bit more, still no effect. Then you add a little bit more steering and it very suddenly slows the rotation and snaps back. Now I know 'snap back' is real, but it's as though you need to overcorrect to stop the rotation. And then when it snaps back (including at high speed), visually it seems to involve the car rotating around the central axis rather than the rear pendulum-ing (if that's a word) around the front. After all, that's why that sort of thing is called "fish-tailing" when it happens repeatedly. The central rotation makes it much harder to straighten in time, and lots of experienced skip drivers are snapping out of control like complete novices. I think LFS is the only sim that possible makes this look (at least) realistic by having the rear rotate more about the front rather than the rotation being about the central axis. Any thoughts?


One other *important* thing. In the Skip, when you trail off the brakes at the turn in to a corner, the faster you come off the brakes the faster the car rotates in. Surely that's the opposite of reality - where coming off the brakes should increase rear grip? Indeed, RFB-ing in real life involves coming off the brakes faster so as to get to the throttle quick whenever there's any sense the car is about to over-steer. The fast Skip drivers all come off the brakes very smoothly and it's written into the community-made manual that it's important precisely because coming off the brakes too fast is a cause of spinning. Surely that isn't how it should be?

Since the update where they made such a big (positive imo) change to the FGT and HPD, I've hardly driven. It's probably been a month or two already since I've touched iRacing. I ran a few laps at Lime Rock in the MX5 and noticed much the same thing you're describing.

The only quick conclusion that sprang to mind immediately was that it seemed the cornering stiffnesses of the tires on that car were increased considerably. I.e., the lateral force peak moved to a smaller slip angle. I could tell after the first two or three turns because I was running right over the apexes and had to retrain the steering thingamabob in my head not to do it anymore. On top of that, like everybody else if I managed to slide the car I wound up snapping back the other direction at least as often as I saved it. Before that update I don't remember ever doing that once in this car...

This snap back behavior is consistent with higher stiffness tires to an extent, but I have a hard time believing the real MX 5 tires are really that stiff. These feel like they peak at 4 or 5 degrees, something more like an Indycar tire. If they were that hard to catch a slide with, the series would go bankrupt. This always reminds me of one of the times my client took me for a ride in his Donkervoort S8. This very car right here:

http://www.youtube.com/watch?v=Dp7g1NAMNxE

The pic is wrong in the beginning and it's Wolfgang driving my friend's car during a qualifying lap rather than the race itself, but that's not the point. What I always remember was him telling me how bloody easy it is to drift that car all over the place. Slicks or no slicks, doesn't matter. He said if you give this car to somebody in a parking lot for twenty minutes they'll be able to do it no problem. He then went sideways with heavy throttle through a few turns on a Dutch road to illustrate the point. He's an iRacing member and I can run circles around him. He can't save a slide there if his life depends on it.

Anyway, I have more thoughts on the MX5 that I'll post another time. Been up now for 22 hours and my brain is going dead...

Regarding rotation, if the car's rotating around a different axis this would be a symptom rather than a cause. Computationally this is pretty hard to mess up really. All you do is add up the torques on the car and apply them in a way that rotates it around the center of gravity. The car will rotate around a different axis than that most of the time probably, but it just comes out of the force and torque calculations so is a no brainer to do. The laws of physics are well understood in this area by sim developers everywhere so this isn't likely to be wrong. Things rotate around their center of gravity and translate at the same time, so if there's some other axis of rotation at play here it will just come out of the equations without doing anything about it. I.e., it works the same way in every sim these days, so if that axis is different it's a function of the tires and everything else doing their thing rather than the developer "choosing the wrong axis," so to speak.

I am curious about your perception of the rotation axis location though. BlueFlame seems to share it so maybe one or both of you might elaborate a bit more on the feeling. My first thought when reading your comment on that was "how can he tell what axis the car is rotating around from inside the car?" I'm sure it's some subtle (or maybe not so subtle) motion you're picking up on that gives you that feeling, I'm just at a loss to figure out what it is.

Skip Barber car: The only time I really liked this car a lot was when the NTM first went on it. The massive lift-off oversteer was finally gone, or at least reduced to the point where even I could drive the thing pretty quickly without doing anything that felt unnatural. Sadly, a later update then changed it again for the worse and I couldn't get the thing around the track without babying it. I gave it a shot for an hour or two but finally gave up on it.

On spinning while releasing the brakes: This is an interesting question and at the moment I'm not really sure. What comes to mind is that in my hobby car sim the same thing can happen if the setup or tires aren't good and I've wondered why it happens too, if there's some predominate thing that can be pointed to as a likely main cause. To give a good answer to this I'd need to look into it more. I wouldn't go so far as to say it's bad physics or miscalculations or "Teh Tire modeL is sUck" or anything like that, just that perhaps the tires or setup could use a bit more attention in this area. I'll think about this one some more, maybe test a bit in my sim, and get back to you on this one because I'm curious too...

Last edited by jtw62074, Wed, 28 Dec 2011 21:28.

Oh yes, I've driven Serpent cars there. We have that track too:

http://www.youtube.com/watch?v=yaHbN7XtgUw

See if you can tell which one is real and which is from the simulator. Doug Milliken and I showed this to a room full of engineers at an engineering conference once. It took some time for anyone to figure out which one was the real car at the real track, and which was from our simulator.

Here's a track list with pictures and so on:

https://www.vrcworld.com/tracks/default.aspx

Mach/Heemestede here:

https://www.vrcworld.com/tracks/track.aspx?track=37

I'll try to remember to come back and let you know more about the Haarlem track when I talk to Pieter next. I know Pieter is talking with somebody about buying carpet, walls, and so on for a track to be built in Haarlem. I assumed it was to be a temporary track with the same layout he designed, but I guess I better make sure before saying that, eh?

Last edited by jtw62074, Wed, 28 Dec 2011 19:37.

What track are you referring to? It must be very similar to the one in the video. This one is actually our own design by Pieter Bervoets, founder of Serpent (modeled by Tony West). It's one of a handful of the fantasy tracks we have. He's hoping to build it in reality in Haarlem, NL, for the world championships if I'm not mistaken. This may be a track going from a sim to the real world instead of the other way around for once

I'll tell Pieter what you wrote. He'll get a kick out of that

Last edited by jtw62074, Wed, 28 Dec 2011 18:52.

1:12 scale electric 10.5T spec cars were released a few days ago:

http://www.youtube.com/watch?f ... mbedded&v=Os--1pBwcU4

We're on a free 30 day trial now and things will most likely stay that way.

That's wicked, Scawen. Great stuff. Looking forward to buying the release

Quote from XCNuse :

I would be more than willing to pay another $20+ to help development and help the community. And I know quite a few other people will too (not the first time I've said this either)

I spent $20 in the last two days playing a facebook game. Probably will do it again over the next two or three days.

On LFS the bang for the buck is unbeatable. I probably spent less than $0.01 per hour of enjoyment I've had out of it. I'll likely buy whatever the guys put out next. $20 is chump change. How much work do people that complain about development progress have to really do to come up with $20?

Quote :

I have no problem giving up a little bit of my paycheck to help the development. I just need proof of development to justify a payment.

We can make it even simpler than that: They can sell an upgrade to S3 as planned and we simply buy it then.

I thought I was wrong once, but I was mistaken. :spin: