What I don't understand is why people in general can't seem to comprehend why things like this happen. People look all over the place for reasons like gun laws, mysterious mental illnesses, violent media inspiration etc. What about the most simple and obvious explaination?

People like Cho Seung-hui get harassed, bullied and humiliated all their lives, they only know joy and pleasure from watching other people experience it, they have no friends, they are ultra shy and will probably never manage to get a girlfriend. When they've had enough of this "life" they decide to end it and if they are angry enough they will take others with them. Really, with all the crap I've seen people take in my life it's almost surprising there aren't more of these kind of incidents.

IMO there isn't even that much we can do to prevent them. There always will be weak and unhappy people and even when they are recognized as being dangerous, as was the case with Cho Seung-hui, the concept of individual freedom should and does still prevent us from locking them away before they have actually broken the law.

How he could stroll into a post office after becoming a murderer and then continue his killing spree is a question that needs to be answered though.

Quote from Glenn67 :

Thats the way I see it

1 and 2 are both under preload conditions without any or minimal dynamic torque transfer from the driveshaft. i.e. off throttle, brake and or gearbox in nuteral. 1 discribes straight line conditions or mild cornering were the difference in torque between the two wheels (generated by the momentum of the car and different paths the outer wheels are traveling) is not enough to overcome the preloaded clutch plate and cause them to slip. 2 deiscribes the same cornering were the forces are enough to cause the plates to slip.

3 is the normal operation of the diff (which is now only in effect above the preload setting) and can still be split into power and coast so there is 4 phases I guess. Also for the dynamic torque transfer there must be two states were under certain conditions it give a fully locked characteristic and a semi locked (slipping plates) also no?

So that would make it how many states of operation

Great! I understood every word and what you say is 100% in agreement with my understanding of the subject, including the things I hadn't thought of before like the case where the diff is locked while not in preload mode. To me this is an indication that our reasoning has been sound. It's been a nice discussion, now let's hope someone with RL experience drops by. Oh, and BTW that's 8 states of operation. :eek:

Another thing I thought of: with an open diff any friction in the gears would pretty much have the same effect as preload. Would real cars have enough friction in the diff to influence the handling of the car towards understeer? If so I guess sims would need to add preload to open diffs as well.

Last edited by J.B., Wed 18 Apr 2007, 04:32.

And then the torque difference stays at the preload value until the input torque reaches a certain level? Make sense? Where's Todd?

Quote from Vain :

@J.B.
Let's imagin input torque at the diff is 0 Nm. Preload is 100 Nm. The car is going in a straight line.
Using your calculation for the case preload > input torque I'd get to a torque at the left wheel of 50 Nm and torque at the right wheel of -50 Nm.
This is obviously not true. What didn't I understand? This is the point why I assumed a clutch to operate, which requires a constant in the unit of Nms/rad.

Vain

Just leave complicated stuff like driving in a straight line out of it will you?

But seriously, when left/right torque differences are very low I would imagine that the diff indeed behaves like a fully locked diff due to the friction plates not slipping but being under static friction. I think as soon as you try to go round a corner and the plates begin to slip you will notice there is a torque difference between the wheels i.e. the car isn't as willing to turn in as it would be without an LSD. There really could be -50 at one wheel and +50 at the other. As long as the forces caused by the steering front tyres are bigger the car will still go round the corner, just with less oversteer.

So maybe we have three states?

1) locked when the forces applied to the wheels don't cause the clutch plates to go from static to dynamic friction and start slipping

2) in the "preload" state: clutch is slipping and the torque difference between the wheels is constant

3) in the "normal" state: clutch is slipping and the amount of torque difference is defined by delta_torque = locking_factor * input_torque

I guess it's either that or I have gone completely bonkers trying to understand this stuff. :Eyecrazy:

Last edited by J.B., Tue 17 Apr 2007, 21:24.

Just to clear one thing up: in normal cornering the outside wheel is the faster spinning wheel. The inside only gets faster if it gets overloaded and starts spinning.

So in normal cornering more torque is applied to the inner wheel and if you think about it you will notice that this difference in torque will try to rotate the car away from the corner which is the exact reason why LSD's help against oversteer.

Quote from evilgeek :

edit - nevermind, i got it. preload only affects the locking if set too high...

Yep. It kicks in when the torque difference gets low. What you are setting is when exactly this happens.

BTW, maybe you could be bothered to edit the my quote in your above post as there were some errors in it.

Quote from Glenn67 :

LOL I was just about to ask you that question...

hehe, you posted while I was editing my above post. Looks like we had the same thoughts twice in 6 minutes.

Quote from Vain :

I also have a question.
Why is the unit of preload Nm?
...the torque exerted is some constant by the difference in angular velocity between the two wheels...

Probably this assumption is wrong for a clutch pack diff although I can't find any information on this. In fact it's correct for a viscous clutch which has Nms/rad as its unit in LFS.

Quote from AndroidXP :

Someone really needs to calculate through a few test cases of clutch LSD operation (like I failed to), otherwise I fear the confusion will never clear up.

It' really quite simple.

An example for accelerating in a corner with 40% locking:

1. Find out how much torque is coming from the engine. For example the FOX has a max torque of 221 Nm so I'll just pick the case where I'm using about half throttle to accelerate --> torque_engine = 100 Nm

2. Multiply this torque with the gear ratio and final drive ratio to get the torque at the diff. Example: torque_diff = 100 Nm * 1.6 * 4 = 640 Nm

3. use

delta_torque = locking_factor * torque_diff

to find what the torque difference between the two wheels is

--> delta_torque = 0.4 * 640 Nm = 256 Nm

Now if this number is bigger than the preload then
--> torque_inner = 640/2+256/2 = 448 Nm
--> torque_outer = 640/2-256/2 = 192 Nm

If the preload is set to more than 256 Nm, say 300 Nm then
--> torque_inner = 640/2+300/2 = 470 Nm
--> torque_outer = 640/2-300/2 = 170 Nm
--> more locking, less oversteer than before

I hope that clears up some confusion.

Last edited by J.B., Tue 17 Apr 2007, 20:08.

Yep. But now there's one thing I can't quite get my head around. In a free rolling state there is no torque being transferred between the wheels and the gearbox. Now roll around a corner. The preload is now supposed to be the amount of difference in torque between the faster outside wheel and the slower inside wheel. What does this mean if there is no torque there to transfer, so to speak?

EDIT: I think I know. The LSD does indeed still make sure that the preload is the difference in torque between the two wheels. The only way it can do this when there isn't any torque there, to distibute between the wheels, is by applying a braking torque to the outside wheel and an accelerating torque to the inside wheel. --> less oversteer.

Last edited by J.B., Tue 17 Apr 2007, 20:14.

Quote from Glenn67 :

Hmm no I'd think that if you had 70% locking on power it would be saying that 70% of the available torque would be going to the wheel with most grip

Almost. The deciding factor on which wheel gets more torque is wheel speed not grip. The slower wheel always gets more. So when both wheels are gripping it's the inside wheel that gets the extra torque (increasing understeer) but when it starts spinning it's the outside wheel.

And the locking factor doesn't really indicate a percentage of torque or power, it just tells you where the diff is on a scale of 0% = open diff to 100% = locked diff. As an equation:

locking_factor = (torque_left - torque_right) / (torque_left + torque_right)

So 70% locked means that the difference in torque between the faster and the slower wheel is 70% of the total torque. So if the wheels are getting 100 Nm of torque then the faster wheel will get 15 Nm and the slower wheel will get 85 Nm (85 - 15 = 70).

Quote from Gentlefoot :

70% power locking means that the diff will allow the wheels to turn at up to 30% different speeds.

Sorry, that's wrong. Clutch pack diffs don't react to wheel speed differences. The slower wheel always gets more torque than the faster wheel but just how much more is not influenced by wheel speeds. See the formulas I posted above.

EDIT: argh, beaten by the Bob!

Amazing. I have certainly been convinced that LH is the real deal for quite a long time now but I would never have thought that LH would take only 3 races to beat the double world champion Alonso fair and square for the first time. Joint WDC leader!

The race was a bit boring but I think that the track is partly to blame for that as even the GP2 races weren't that great.

Another thing. What's up with the soft and hard tyre compounds? Has anyone noticed any meaningful differences between them? It seems to me that the performance difference between the soft and the hard tyres is negligible in terms of laptime so the whole fuss about the spectators being able to tell the soft tyres from the hard was pretty pointless.

Well explained Glenn. Put into a formula a clutch pack diff is actually quite simple. With an open diff each wheel always gets the same amount of torque as the other. What an LSD does is it transfers torque from on wheel to the other i.e. the torques are no longer the same for each wheel. The difference in torque is simply:

delta_torque = locking_factor * input_torque

So of you set for instance 80% locking factor then the actual torque that is trasferred from one wheel to the other is not constant but depends on how much torque the final drive is actually transferring between the wheels and the gearbox. When this torque is low (after releasing the brakes) the effect of the LSD is low. All preload does is set a minimum amount of difference in torque between the two wheels.

So while saying the diff is 80/0/80 isn't entirely correct, it is what the old LFS diff felt like. The new diff works just as advertised and makes much more stable and realistic setups possible. :up:

Last edited by J.B., Tue 17 Apr 2007, 20:11.

Will be interesting to see if LH and FA are on different strategies or if LH really is already on such a high level. First corner should be interesting as Massa has said he won't leave as much room as he did in Sepang again.

Here`s a great link that lists which panels are used in which screen models.

http://www.tftcentral.co.uk/panelsearch.htm

In short TN panels aren't that great, IPS and PVA panels are better and Dell sells the cheapest non-TN screens. They also have more features than most others like HDCP and Aspect Ratio controls.

Last edited by J.B., Wed 11 Apr 2007, 17:56. Reason : oops forgot the link

Quote from Bob Smith :

Yeah but that's only true for interlaced video, where half the screen updates each frame. On progressive material the fact each frame gets drawn twice isn't really going to help smoothness.

True. But that's only the case for content that is coming from real film cameras as opposed to video cameras such as the ones used to record sports and racing. Video cameras record at 50/60 fields per second yet all videos found on the internet are deinterlaced to 25/30 fps which is a technique that should really only be used for film content. But in a day and age where youtube and FLV videos are popular what can you expect?

HDTV cameras can of course record at 720p 50/60 fps but at the rate things are going in Europe it doesn't look like HD is going to go mainstream anytime soon.

Quote from evilgeek :

for reference, TV is approx 30 fps.

A myth that just doesn't want to die. A TV screen refreshes at twice that rate which means 50-60 Hz motion smoothness. For some reason not many people care or are aware of this which is the reason why every video from the internet that is not a hollywood movie (24 fps) looks like crap, especially sports.

GTR 2 when I want to drive real tracks. It's the only ISI game where the physics don't put me off completely.

Glad you fixed it! I love it when security programs cause problems that are more severe than the problems they are supposed to prevent. No firewall or Antivir here. No Problems.

Quote from Davo :

ALl those have built in AR adjustment so the monitor doesn't need to do it. Hell I don't even use the AR adjustment on my tv because all the other boxes have automatic AR adjustment and provide a fully digital signal.

Can you explain this in detail? Say my screen has 1680x1050 pixels (16:10) and I connect a HDTV decoder box that outputs a 1920x1080 (16:9) signal. Now the screen with no aspect ratio options will take the 1920x1080 signal and resize it to 1680x1050 thus distorting the AR.

What the HDTV box needs to do to prevent this is add extra black pixels to the top and bottom of the image for which it also needs to know the AR of my screen.

Is this what these kind of devices typically do?

Quote from Davo :

If you get a TFT that uses DVI you can use your video card to adjust the ratio automatically so the monitor doesn't have to do it. I wouldn't even bother with an analog screen really.

But what about connecting a Blu-Ray player or a PS3 or a HDTV decoder box? For me it's the monitors job to deal with the AR not the GPU's.

Quote from Niels Heusinkveld :

Running fullscreen it might not be. Some monitors have an 'aspect' button (mine has) which has a few modes:
1 fill with aspect (i.e. keeps aspect ratio and scales it as big as fits)
2 fullscreen (i.e. full screen: it will not remain aspect
3 native mode (i.e on a 1600x1200 screen, running a game in 800x600 will make it a small centered 1/4th of the area using window

*dusts off thread

I'm currently looking for a TFT and have been very surprised to find that most monitors don't support any of these settings, let alone by a single button press. In fact most screens stretch to full screen no matter what kind of input you give it! So which screen are you using?

Thanks for the patch, the new sounds and the HiRes mirror are great additions!

Quote from Scawen :

The viewed car is green, the others are yellow, orange and grey.

Small suggestion. One thing I sometimes miss in longer races is the information if the cars close to me are actually on the same lap as me or not. It would be nice if the map could be used to tell me at a glance if I'm actually fighting for position or lapping/being lapped. Maybe a new colour for cars that have lapped me and larger arrows for the two cars that I'm currently competing with i.e. the cars that are directly in front and behind me in terms of race position?

You mentioned two system freezes in two different games in this very thread. Computers that are working properly don't do that. Freezes and BSOD's are only very rarely caused by normal software applications. Usually the cause for these kind of errors are driver bugs, faulty hardware or overheating. When I had some problems with freezing a while ago it turned out to be faulty RAM which I found out using memtest. Haven't had any problems since.

You are obviously having hardware issues. Try running memtest, prime95 and 3dmark for several hours each to find the problem. Depending which ones fail and which ones don't you can start guessing at which part is faulty.

About your original question: LFS doesn't have AA/AF settings but there is nothing wrong with using the driver settings to do this. LFS looks MUCH, MUCH better with AA/AF, in fact for me it's more or less unplayable without it as it strains my eyes. I doubt there will be a frame rate hit with your card.

Quote from Vain :

The basic thought when driving a clutch pack diff in LFS always is "Never, ever, operate the diff between coast and power or you'll oversteer."

Exactly. If anyone wants to see this effect just give the MRT a go with the clutch pack diff.

What I wonder is what is the underlying reason for this effect? Why do LFS cars have to rely so strongly on the diff to stop oversteering? Getting a car to handle well shouldn't be too difficult with a real car. I'm guessing there are still some problems with the tyre physics (as I assume that the rest of the physics should be understood well enough to be free of errors) but I can't pinpoint what would need to change to improve this.

Aerodynamics testing
Tyre testing
Driver