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w126
S3 licensed
Quote from Juls :When I have time I will check it...there is a tool somewhere to see precisely which force is sent to directX. I will use a constant speed, then turn the wheel a given angle, wait for steady state and check the force strength. Then I will see if it's a line or a sin curve.

Now I understand, you meant the situation of varying wheels angle at a constant speed. Then FFB is directly proportional to sin(WheelsAngle), because it's inversely proportional to the turning radius (if a car is running well below grip limit) and the turning radius is inversely proportional to sin(WheelsAngle).
w126
S3 licensed
Quote from Juls :I talk here about cornering forces....forces applied by the road on the wheels through the trail (mostly mechanical trail caused by caster*sin(wheelsangle)). Obviously these forces are zero when wheel is centered (in LFS and any other sims), and increase with wheel angle. Mechanical trail is almost zero when wheels are in line.

Is it the same mechanical trail that is defined below?
Quote :Mechanical trail is the longitudinal distance measured in side view between the center of the tire contact patch and the intersection of the steering axis with the ground. Mechanical trail and caster determine the moment arm about the steering axis for lateral (cornering) forces acting at the tire contact patch.

(http://www.tamusae.org/index.p ... w&id=29&Itemid=48)

Imagine a car sliding laterally with no polar body rotation (to make it simple) and the wheel centered. Wouldn't you have some force on the steering wheel?
w126
S3 licensed
Quote from Juls :- Rack displacement is proportional to steering wheel angle.
Disp=c1.SteeringwheelAngle

Some cars use changeable gear ratio (dependent on the angle) here.
Quote from Juls :- trail, hence FFB is in sin(WheelsAngle)
FFB=c2.sin(WheelsAngle)

I don't understand this part. That would mean you can't feel any force when the wheels angle is 0, which is not true. Using cosine in that formula would make more sense to me, that is if I have even the most remote understanding of what it's all about.
Last edited by w126, .
w126
S3 licensed
What if a kitten is killed in the 50th century everytime you start a new thread, lerts?
w126
S3 licensed
I think the colour of horizontal forces is related to slip fraction value for a given wheel. The slip fraction is defined in this post.
w126
S3 licensed
Quote from Juls :I like the very calm guy crossing the bridge, smoking, like nothing strange is happening

A brave man, and he was just bitten by a dog he tried to save from the car.
http://www.wsdot.wa.gov/tnbhistory/tubby.htm
And AFAIR it were the turbulences that caused the resonance.
w126
S3 licensed
Quote from Juls :This table was filled by a guy called Gustave Eiffel.

Then I guess the builders of "Galloping Gertie" bridge (http://www.youtube.com/watch?v=j-zczJXSxnw) didn't use that table. Maybe because its author was not American? Or did they?
w126
S3 licensed
Last time I checked it looked like there are at least 2 contact points (rays used for collision detection) per tyre. They are spread laterally at the bottom of the tyre.
If anyone doesn't like it, well, your game runs faster thanks to it.
w126
S3 licensed
In that blue-silver colours it looks to be remotely inspired by this Morgan Aero.
http://www.7extrememotorsports ... rs/morgan-aero-8gt-02.jpg
w126
S3 licensed
Quote from gezmoor :Interesting. I wasn't aware of that. What other info about the vehicle dynamics can be output in this way? Anything?

Just looking at the specification of CAR_info.bin files suggests a simple physical model which could use all the car properties listed in it. However, it is not complete. For example, aerodynamic components are provided with their lift and drag coefficients (using wing angles specified in a given setup) but this is not enough to know exactly the aerodynamic forces when the car moves at an angle or with cross winds.
w126
S3 licensed
Quote from gezmoor :I don't doubt that all of the above is probably true. But how do you know this to be the case?? Has any of it ever been stated by the developers or is it just assumption because of the way the cars in LFS appear to handle?

LFS is able to generate some output data (RAF and CAR_info.bin files) that we can try to process and analyse. Regarding the tyre normal load, it is possible for example to see how it affects the lateral grip of tyres: http://www.lfsforum.net/attach ... tid=4791&d=1136410311 (this is from on older LFS version).
Quote from gezmoor :True, however even road car manufacturers go to some length to shape their cars to ensure they have relatively low coeficients of drag. This aspect is going to be very important once dynamic wind is included in LFS, especially for the lighter single seaters. The current F1 cars for example appear to be particularly sensitive to cross winds, (apparently).

F1 teams have supercomputers a thousand times more powerful then a typical gaming PC (http://www.tgdaily.com/content/view/36905/135/) and they are still very far from doing aerodynamics simulations in real time. Did I understand it correctly, do you want it in real time in a computer game? It's around 40 years away it seems, if we are lucky.
w126
S3 licensed
Torsen differential may also have different locking for power and coast modes.
http://www.zhome.com/ZCMnL/tech/Torsen/Torsen.htm (4.3)
w126
S3 licensed
I have just checked the RAF file. At 43.00 s the sum of vertical loads is 9544.29 N. At 0.00 s it is 9571.98 N. These are suspension loads taken directly from RAF file. The whole car mass is 1010.90 kg and the unsprung mass is around 50 kg, so the loads seem to be correct.

The image below shows the sum of tyre normal loads calculated with my RAFTyreExtract (I had to fix it because it turned out to be incompatible with FWD car data). These tyre normal loads are approximately the sum of suspension vertical loads, unsprung mass weight and the forces equivalent to wheel vertical accelarations. Again, it looks reasonable, as it oscillates around 10 kN.
w126
S3 licensed
Quote from GrEgce :there is a chance that this perpendicular loads are suspenssion loads, then i have to add 20kg for every wheel and unknown value for suspansion weight. But at the end there are still just 940kg...

They are suspension loads. Could you attach this RAF file here?
w126
S3 licensed
New-generation Skip Barber car at Lime Rock. It's in the interview with Alison Hine, GPL beta tester.
w126
S3 licensed
There is some more information on KartSim in this thread http://www.ogre3d.org/phpBB2/viewtopic.php?p=270536
w126
S3 licensed
Providing proofs of the existence of God is just funny. Religion is not science. If you believe you don't need any proofs.
Even atheists may admit it's possible that our whole universe is just one of the simulations run by some civilization much more advanced than ours. We may be just characters (the dumb AI ) in a computer game used be some kid. If this is true then for any practical purpose (if any) this kid is our god.
w126
S3 licensed
In Melbourne after 25 laps he was 1:26,74 behind the leader. I think this shows his real speed with the car he has now.
w126
S3 licensed
Looking at this report http://www.fia.com/resources/d ... Race_History_Chart_08.pdf I cannot understand how Bourdais could pit on lap 28 legally, in accordance with regulation 40.6 (http://www.formula1.com/inside ... regulations/6839/fia.html).
Last edited by w126, .
w126
S3 licensed
Quote from nihil :Interested to know where the screenshot came from... Googling iRacing and Radical got me nothing like that shot.

It's from RSC.
http://forum.racesimcentral.com/showthread.php?t=312351
w126
S3 licensed
I'm not sure if you are aware that you can obtain what looks like an equivalent of A*Cx*ra/2 from CAR_info.bin files.
http://www.lfs.net/?page=CAR_INFO_BIN
Quote :// Now 4 aero blocks - rear wing, front wing,
undertray, body : 20 bytes each)

128 Position : x, y, z
Lift : multiply by speed squared to get lift value
Drag : multiply by speed squared to get drag value

w126
S3 licensed
Quote from Minimaxman :Well, recording it without sound makes no difference, still runs at 8fps. And this is from a replay. Slowing the replay down by half also makes no change.

Try lowering the target framerate in FRAPS (to limit the load it puts on the computer). For example set it to 10 and record the replay slowed down 4 times. Then speed up the captured video and sound (using audio stretch filter in VirtualDub) and get 40 fps video.
w126
S3 licensed
There is a mistake in this part of RAF spec, just notice the strange order of offsets. The above code reads forward (Y) forces. Use the offset of 8 inside dynamic wheel info block to get X forces.
w126
S3 licensed
Oops, sorry, I guess I've never been interested enough in FWD cars.
FGED GREDG RDFGDR GSFDG