Re: [Flightgear-devel] Abnormal surface friction factor

[Erik H. <er...@eh...>]

On 6/15/23 10:49, Dany wrote:
> I think I progressively understand the logic (including the 50 factor).
> 
> Everything starts from the (geodinfo) rolling_friction.
> On asphalt, this (geodinfo) rolling_friction is given the value 0.02. 
> Which, multiplied by 50, gives rolling_friction_factor = 1. In this 
> case, no correction, the final rolling friction coefficient is the value 
> given in the aircraft FDM:
> (in the FDM, e.g. <rolling_friction> 0.03 </rolling_friction>)
>   /fdm/jsbsim/gear/unit[]/rolling_friction_coeff
> 
> On another terrain, the (geodinfo) rolling_friction has another value. 
> Let's take "grass": 0.1. Which, multiplied by 50, gives 
> rolling_friction_factor = 5. Thus, the final rolling friction 
> coefficient = 5 x the value given in the aircraft FDM:
> 5 x /fdm/jsbsim/gear/unit[]/rolling_friction_coeff
> If the aircraft (FDM) initial rolling_friction_coeff = 0.03, it gives 
> 0.03 x 5 = 0.15 for the final rolling friction coefficient.
> 
> Example: C172P, 180hp. Full thrust at rest: 549 lbs.
> If the aircraft weight is 2000 lbs, it will not move if the final 
> rolling friction coefficient is greater than 549 / 2000 = 0.275.
> 
> If the aircraft will not move on a terrain, the first (and easier) thing 
> is to check if the (geodinfo) rolling_friction is not the culprit.
> 
> Is it true? Please fix me otherwise, thank you.

Yes, that's the idea.
This would allow a different friction factor for different terrains 
while preserving the possibility to set the friction coefficients in the 
JSBSim configuration file.

Erik

-- 
http://aeonwave.xyz
High performance audio scenegraph and sound simulation.