• 0 Vote(s) - 0 Average
• 1
• 2
• 3
• 4
• 5
Weight of wheel
08-07-2010, 07:35 PM,
 cologne Member Posts: 203 Threads: 35 Joined: Mar 2007
Weight of wheel
Where is the weight of the wheel and unsprung part of suspension and brake?

Before:
Code:
```[ wheel-FR ] mass = 19```
08-09-2010, 06:36 AM,
 NaN Posting Freak Posts: 2,024 Threads: 120 Joined: Jan 2010

It is calculated from tire dimensions. The densities are chosen to match real world tire/rim weight.

Code:
```    // calculate wheel inertia/mass     float tire_radius = tire.GetRadius();     float tire_width = tire.GetSidewallWidth();     float tire_thickness = 0.05;     float tire_density = 8E3;          float rim_radius = tire_radius - tire_width * tire.GetAspectRatio();     float rim_width = tire_width;     float rim_thickness = 0.01;     float rim_density = 3E5;          float tire_volume = tire_width * M_PI * tire_thickness * tire_thickness * (2 * tire_radius  - tire_thickness);     float rim_volume = rim_width * M_PI * rim_thickness * rim_thickness * (2 * rim_radius - rim_thickness);     float tire_mass = tire_density * tire_volume;     float rim_mass = rim_density * rim_volume;     float tire_inertia = tire_mass * tire_radius * tire_radius;     float rim_inertia = rim_mass * rim_radius * rim_radius;```
08-09-2010, 09:31 AM,
 cologne Member Posts: 203 Threads: 35 Joined: Mar 2007

NaN Wrote:It is calculated from tire dimensions. The densities are chosen to match real world tire/rim weight.
Not a good idea because:
- masses an inertia may vary between steel-wheels/normal tyre and cart wheels/slick and rally car or a formula car,
- the result of weight, inertia computation is completely intransparent (canÂ´t add masses in .car-file to totalweight) and
- the unsprung parts of suspension/brakes are unconsidered!

Code:
```[wheel-n] mass = 20 inertia = 0.04```
...as optional parameter. Not in 'wheel-n' defined parameter are computed!
08-10-2010, 04:51 AM,
 NaN Posting Freak Posts: 2,024 Threads: 120 Joined: Jan 2010

Added optional mass, inertia parameter to wheel declaration in rev 2847.

Quote:Not a good idea because:
- masses an inertia may vary between steel-wheels/normal tyre and cart wheels/slick and rally car or a formula car,
- the result of weight, inertia computation is completely intransparent (canÂ´t add masses in .car-file to totalweight) and
- the unsprung parts of suspension/brakes are unconsidered!
I'd avoid adjustments of wheel properties to get a certain handling. You would tune for the current implementation. And it has its own load of issues (like low inertia values).

I guess you've got some real-world wheel, unsprung parts mass and inertia values?
08-10-2010, 05:31 PM,
 cologne Member Posts: 203 Threads: 35 Joined: Mar 2007

Sorry, too slow, to catch TrulliÂ´s rear wheel with unsprung masses in Hockenheim, :-(
NaN Wrote:I guess you've got some real-world wheel, unsprung parts mass and inertia values?
08-11-2010, 07:36 AM,
 NaN Posting Freak Posts: 2,024 Threads: 120 Joined: Jan 2010

Try to be faster next time, hehe.

Forum Jump:

Users browsing this thread: 1 Guest(s)