Necromancy! :eek:

...Sorry for awakening the dead, but I sincerely think this should be given a thought. And by the way, it's not in the suggested improvements log.

Vain

Quote from NikLaw :

Normally, you can drive a car with two fingers, you don´t need much strength due to servo drive.

Unless you use a car without power steering. I can tell you that in the car I used for the track two fingers were not enough (215 Yokohama A048 tyres in the front and no power steering).

Vain

Are scenes from the STCC league races allowed?
This is the battle for 4th place from round 3 (Aston Club) of the STCC. See the linked race results to find out who made it.

Vain

I don't really think there is much difference in mentality between sim and RL racing.
Basically all racers, sim or real, can be sorted by patience. Much patience = good racer, few patience = bad racer.
Many BTCC drivers: No patience -> bad racers
Many new LFS drivers: No patience -> bad racers
Many WTCC drivers: Much patience -> good racers
Many seasoned LFS drivers: Much patience -> good racers

Consider though that 'good racer' doesn't always mean quick racer. But having patience means that you don't want to drive a world record lap each time you're on the track so you are likely to be consistant which ultimately makes you considerably quick. But absolute pace, measured in personal best laptime, has few to do with patience.

Vain

Quote from Vain :

2. Many high end vehicles sound very much like a trumpet. Click here for a real vehicle (...with wrong description...) and here for an LFS car.

I thought about it for a while. Is it possible that this sound effect may be cause by changing diameters of the exhaust pipe?
I originally compared the sound to a trumpet, and what makes a trumpet special is that it's diameter changes. This is also very possible for real exhaust systems. Even if you try to avoid it, the different parts of the exhaust system need different diameters. This could cause the same effect and thus contribute to that sound.

I wonder wether the mathematical solution of such a differential wave-equotation is simple enough to be used as an element in the LFS sound simulation.

Vain

That isn't too bad.
Obviously it's the wrong way to generate them, but it's nice to know that there indeed seems to be an issue about low frequencies.
The first step to an improvement in the simulation is the step from "There is something wrong" to "That's what's wrong".

Vain

From comparing LFS's engine sounds with onboard videos I think there are two points I can put my finger on.
1. LFS seems to lack a bit regarding very low frequencies. Maybe those aren't produced by the combustion but rather by other resonating objects (cylinder block, chassis) which would also explain why it is so difficult to grasp.
I don't know how far LFS simulates this, but a real exhaust system oscillates quite heavily under revving. This could cause sound itself, or might be an indication of other oscillating parts.
2. Many high end vehicles sound very much like a trumpet. Click here for a real vehicle (...with wrong description...) and here for an LFS car.
You can also nicely hear how the real engine sound 'flitters', while the LFS sound is very monotoneous. This might have something to do with the oscillation from point 1.

Vain

The 'resize and render myself to google's target resolution'-approach was what I did when I uploaded the STCC #7 Heat 2A video. And it looks crap.
The 'upload in recommended resolution'-approach was what I did this time. And it looks crap.

Vain

Here is yet another onboard video, this time I'm driving a simple autocross layout (thread here).
I uploaded the video to google as a 640x480 video at a bitrate about 2400, and still the quality loss was rather high. I don't know wether I can get above that quality at all.

Vain

Hi.

I fooled around with the autocross editor a bit and decided to release the result.
See attachment for lyt file and here's a video of my driving it (pretty slowly).
If you think that visibility is bad then yes, I know that. In the video you can even see me once aiming for the wrong stack of tyres where I mistook it for the apex. Drive the layout slowly for a couple of times before really going at it. Looking at it from bird's eye view doesn't harm either.

(Actually the name has nothing to do with mining, but more with the fact that it is mine. But thanks to the ambiguity of that word I had a name for the layout and didn't even have to rename it!)

Vain

Last edited by Vain, Sat, 21 Apr 2007 19:37.

I think what's basically killing the fun of driving the FOX is the body downforce.
At slow speeds the car is nice and fun. But even around Fe Gold the FOX gets so much downforce from the body alone that the engine can barely get the rear tyres loose.

Does anyone have numerical data of how much downforce such a chassis would cause?

Vain

Thanks for that thought. This makes a lot sense when you look the pictures undoz posted (thanks a lot for those, undoz! The 'Operational Theory' section of that linked page is great!).

Vain

Last edited by Vain, Fri, 20 Apr 2007 19:37.

Quote from jtw62074 :

What's important here is that preload is not effecting the differential operation at all except in these situations where there isn't very much throttle or braking being used. Anything beyond that and the locking torque from torque bias ratio will win. The triangular shapes devour the preload area underneath it. They are not cumulative.

Hi.
Where does this come from mechanically?
I can believe what you say and try to memorize it, but I'd like to understand how it works mechanically, but technical drawings of LSDiffs are seldom.
If I press two (or however many) clutchplates together to create preload they should always resist torque between them by exerting an opposing torque. Regardless of the torque difference. So if I have set up my preload-less differential to stay locked in situation B in your diff2-picture, and then put additional load on the clutches I can't help but believe that now the differential should be able to resist a higher torque-difference between the driven wheels than before.

Vain

Hidden mode:
The menu items hang on a wooden wall with many stilts. Shoot a cube between the two rightmost stilts by clicking there. If you hit the correct one of those concrete plates that you can hit by shooting between those two stilts you'll enter the hidden mode.

If that's too complicated, attempt to hit all concrete plates (the breakable ones) on the right hand side of the menu screen.

Vain

Quote from J.B. :

For example if the preload is the amount of tourque the clutch plates can take before slipping then once they start slipping the torque transfered should be a bit smaller than the preload value as dynamic friction coefficient is < static friction coefficient.

I can only judge by the technical drawings and texts linked here. Those say that the torque exerted by the differential due to preload is constant over the whole range of slipping.
From looking at the drawing I think that preload is also active while power is transferred through the diff. After all, all you're doing is pressing clutch plates together, they don't gt loose because power is transferred through the diff.
So when the diff is slipping the exerted torque should be 'preload + torque at input shaft * locking_factor', wether the torque at the input shaft is big or small, the clutch plates we press together with preload shouldn't mind. Or should they?

In that case the diagram above would be wrong.
Now you made me draw diagrams with paint with a touchpad.

Vain

Quote from Forbin :

Honest teams need not apply?

Just like in real racing.

Vain

Nice game. The after-match struggling is silly. Look what my highly skilled sumo-machine managed to do while trying to stand up.

Vain

Let's put it straight:
The car with LSDifferential with preload drives down a straight. The driver leaves throttle and brakes alone and starts turning in left.
The front wheels start turning the car, which causes forces on the rear tyres. The front wheels try to make the left rear wheel slower than the right rear wheel.
These forces mean that there is a torque at the differential.
If this torque is smaller than what you set preload to the differential resists the torque and acts like a locked diff.
If this torque is bigger than what you set preload to the differential starts slipping. The torque it exerts is exactly what you set preload to. f.e. 100 Nm if you set preload to 100 Nm. Regardless of how much the driver turns the steering wheel, the diff won't exert more torque than that, 100Nm and no more.
If the driver starts accelerating now the differential is loaded and exerts additional torque from the power-lock setting, and pretty soon preload is neglectible.

That is my current position. No warranty though.

Vain

The first video was definitely not staged. But indeed, during the first three laps both Hyperactive and me tried to be careful, we were driving a 15 minutes race after all and you don't want to spoil that with an overambitious move in lap 1 .
The second video's quality is, as said, caused by google. Does anyone have some good pointers for the input-quality for upload to video.google.com? The recompression at google is a real problem.
And about the driving in the second video: Those three drivers were fighting for entry into heat 3A. The last of the three would go to heat 3B. From heat 3B the best achievable grid position for the feature race is 13th (the first 12 are finishing positions of heat 3A). And there were merely 10 minutes to juggle it out before the heat ends, so there was quite some pressure there.
Glad you liked it. I'll keep uploading such videos from the heats, depending on wether I see good action somewhere.

Vain

W9 and W10: Is the behaviour that occurs when you exit LFS via the windows exit button while refreshing the server list desired? It takes over 15 seconds to actually exit and shows a blank backgroundscreen in the mean time.
It might be that way by design, but it isn't optimal so I mention it.

Vain

Here's another onboard video.
That's Heat 2A of STCC#7.
Drivers are:
Silva (white helmet, grey/white car)
Horvath (yellow/grey helmet, yellow/black car, appears a bit later)
Me (Black/red/white helmet, yellow/black car)

Google pretty much destroyed the quality. I'll have to try around with the next videos to find something google accepts without completely shredding it.

Vain

I fraps'ed a nice fight in Heat 2A of round 7. Click here. First appearing XRT is Silva (from the start, white helmet), who during the first lap starts an argument for positions with me (red/white/black helmet, yellow/black car), and later we meet up with Horvath (yellow/grey helmet, also yellow/black car, my teammate). Pickard also makes an appearance as he blasts past us in his FXO on the first lap.

Google-Video pretty much ate the quality (the video was already at the target bitrate and resolution, but was transcoded to flv *argh*) but we stayed so close to one another it doesn't matter.

Vain

I read about that in those linked articles.
So the preloaded LS diff behaves like a locked diff until the torque difference reaches preload?

Vain

@evilgeek:
That explains well how a LSD diff works under load, but I'm aware of that. I'm talking about: What kind of torque does the LSD diff exert under a given difference in wheel speed (cornering), with no input torque and a given preload setting.
Either the unit of the setting is wrong or I lack a fundamental understanding of what happens in that situation.

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