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GP Bikes => Bikes => Mods => Physics => Topic started by: HornetMaX on December 20, 2013, 01:54:23 PM

Title: One question about physics params
Post by: HornetMaX on December 20, 2013, 01:54:23 PM
I have a fuckzillion questions about the unencrypted physics parameters and I know there's no way Piboso can answer them all, would take forever and anyway it's not the right time for that.

@Piboso: out of curiosity, why are lenght and width of the fueltank specified ? Don't tell me you're actually simulating the sloshing ...

MaX.
Title: Re: One question about physics params
Post by: PiBoSo on December 20, 2013, 01:59:11 PM
Quote from: HornetMaX on December 20, 2013, 01:54:23 PM
I have a fuckzillion questions about the unencrypted physics parameters and I know there's no way Piboso can answer them all, would take forever and anyway it's not the right time for that.

@Piboso: out of curiosity, why are lenght and width of the fueltank specified ? Don't tell me you're actually simulating the sloshing ...

MaX.

From width and length and amount of fuel left in the tank, height is calculated.
Then, using width, length, height and mass, inertia tensor of the fuel tank is constantly updated.
Title: Re: One question about physics params
Post by: neoraptor on December 20, 2013, 02:01:02 PM
Do you have some documentation/schematics about the physics?
It would really help to develop new bike  :)
Title: Re: One question about physics params
Post by: HornetMaX on December 20, 2013, 10:25:27 PM
Quote from: PiBoSo on December 20, 2013, 01:59:11 PM
From width and length and amount of fuel left in the tank, height is calculated.
Then, using width, length, height and mass, inertia tensor of the fuel tank is constantly updated.
Pheeew, for a split second I thought that ...

Side question (can't resist, as many are facing troubles creating new engines and I can't play with this stuff on my own at the time): in the "engine" section, the "Ratio" parameter (3 for the murasama) is the primary trasmission ratio, right ?

MaX.
Title: Re: One question about physics params
Post by: PiBoSo on December 20, 2013, 11:28:43 PM
Quote from: HornetMaX on December 20, 2013, 10:25:27 PM
Quote from: PiBoSo on December 20, 2013, 01:59:11 PM
From width and length and amount of fuel left in the tank, height is calculated.
Then, using width, length, height and mass, inertia tensor of the fuel tank is constantly updated.
Pheeew, for a split second I thought that ...

Side question (can't resist, as many are facing troubles creating new engines and I can't play with this stuff on my own at the time): in the "engine" section, the "Ratio" parameter (3 for the murasama) is the primary trasmission ratio, right ?

MaX.

Right.
Title: Re: One question about physics params
Post by: neoraptor on December 21, 2013, 12:40:09 AM
Thanks for the confirmation Piboso.
My R6 engine is now working much better !!

I still have a small problem about the clutch. How to adjust it properly?
Could you describe how it is intended to work?
I manage to make it work by trial and error method, and would like to know what is the "proper way" to do it.
Title: Re: One question about physics params
Post by: PiBoSo on December 21, 2013, 12:50:49 AM
Quote from: neoraptor on December 21, 2013, 12:40:09 AM
Thanks for the confirmation Piboso.
My R6 engine is now working much better !!

I still have a small problem about the clutch. How to adjust it properly?
Could you describe how it is intended to work?
I manage to make it work by trial and error method, and would like to know what is the "proper way" to do it.

Take the maximum engine torque, multiply it by the engine primary ratio, and add something like 20%.
Title: Re: One question about physics params
Post by: neoraptor on December 21, 2013, 01:16:36 AM
Thanks for the tip :)

Are there other important parameters I need to take care of?
How do I build the braking torque curve?
Title: Re: One question about physics params
Post by: HornetMaX on December 21, 2013, 11:51:02 AM
Quote from: neoraptor on December 21, 2013, 01:16:36 AM
Are there other important parameters I need to take care of?
I suspect the answer to be something like "yes, all of them"  :)

Quote from: neoraptor on December 21, 2013, 01:16:36 AM
How do I build the braking torque curve?
I tried to ask around to some knowledgeable people (at least, more knowledgeable than me).

To get the braking torque curve of a 4-stroke 600cc from the 4-stroke 990cc we already have, the basic idea would be to scale down the 990 braking torque by a factor equal to the ratio of the piston's surface of the two engines (i.e. the ratio of the square of the bore of the two engines). Then you will need to adapt the rpm range, as necessary. If the bore measure is not available, just use the ratio of the engine sizes (600 / 990), should do it too.

For sure it's not exact, it's (relatively) valid only for same engine type (4 strokes) and for same cylinder numbers (4 vs 4).

As a genral rule, if you have less cylinders (e.g. a 3-cyl 990) you'll have more breaking torque than the same volume 4-cyl. How much more ? Hard to tell, something like +15% from 4 to 3, +30% from 4 to 2, and +70% from 4 to 1 (same volume, of course).

For 2 strokes it's more complicate as some engines even had 2 cranksahfts ...

MaX.
Title: Re: One question about physics params
Post by: neoraptor on December 21, 2013, 12:41:21 PM
Ok. I found the bore and stroke measure for the R6 : 67.0 mm × 42.5 mm (2.64 in × 1.67 in)
However, no idea of these measures for the 990.

I also took the 990 motor for reference, but had to reduce engine braking torque a lot more (actually, it is about 0.4x the 990) !!

@Piboso: I tried your modification (going from Clutch's MaxTorque 300NM to 185 (about 75NM * 2.075 * 120%), but it is actually worse.
I always have the same problem when reducing the clutch torque : I lose the rear end much more easily when switching a gear under.
Is there some kind of antidribble available (to avoid locking the rear wheel when going a gear under)?




My braking torque curve is as follow :
   point0 = 1.250000, -1.615385
   point1 = 32.777779, -3.361966
   point2 = 67.222229, -5.263809
   point3 = 100.000000, -7.325155
   point4 = 132.777771, -10.306749
   point5 = 151.666672, -17.269939
   point6 = 235.333328, -22.791409
   point7 = 331.944427, -27.392632

I put the last version of my R6 here (with still 300NM Clutch MaxTorque), for the test : https://mega.co.nz/#!BFgxzZ6a!FP35V1xnwb_2Kw8C231hAjZQuYVa_UBp9RFx4OtXM2k
Title: Re: One question about physics params
Post by: HornetMaX on December 21, 2013, 03:06:30 PM
Quote from: neoraptor on December 21, 2013, 12:41:21 PM
Is there some kind of antidribble available (to avoid locking the rear wheel when going a gear under)?
For sure, in the 990 cfg you have Slipper/RampAngle/MaxSlip:

Clutch
{
MaxTorque = 490
Mapping = 2
DeadZone = 0.04
Slipper = 1
RampAngle
{
range = 30, 5, 45
setting = 1
}
MaxSlip
{
range = 0.5, 0.1, 1.0
setting = 2
}
}


No precise idea what the parameters in RampAngle and MaxSlip are. Trying to find out ...

EDIT: OK, they must be the slipper clutch ramp angles and the maximum slippage allowed (OK, it wasn't that hard to figure out, but I had to take a quick look at how a real slipper clutch works). Would be nice if these settings were exposed in the garage !

MaX.
Title: Re: One question about physics params
Post by: C21 on December 26, 2013, 11:01:00 AM
[in the "engine" section, the "Ratio" parameter (3 for the murasama) is the primary trasmission ratio, right ?[/quote]
Could someone enlighten me, where to find the Primary Ratio? I can find the gear ratios but no Primary Ratio.
One more question: how is the Chassis Mass defined?
Title: Re: One question about physics params
Post by: neoraptor on December 26, 2013, 11:26:04 AM
You find the primary ratio in the tech specs normally ;)
Example here for the R6 : http://www.yamahamotorsports.com/sport/products/modelspecs/8/0/specs.aspx
You have "Primary Reduction Ratio" of 2.073 ;)
Here for the ZX6R : http://www.seastarsuperbikes.co.uk/kawasaki-zx6r.html

For the chassis mass, I made trial & error and found a compromise ;)
Title: Re: One question about physics params
Post by: C21 on December 26, 2013, 01:59:09 PM
Sorry for misunderstanding :) i know where to find the Data in the spec sheets. I Want to know where to find in the .cfg file. ;) I've searched several times but can only find gear Ratio...
I've already finnished my CBR Engines and tweaked  some more Files but i Missed to add the Primary Ratio...

Edit :
Sorry for my blindness...found it...Don't know why i did Not See it.... 8)
Thank you neoraptor :)