Wheel Slip on steam locomotives
#11
Posted 12 March 2022 - 06:06 AM
I've had to tune my models so they physically can't slip. I rather have no slip at all than going from no slip to BRRRRRRRRRRRRRRRRRRRRRR the moment the adhesion treshold is reached. This is with the adhesion modifiers set to default in the options menu AND with my best attempts at tuning the eng files in the best way I know how.
There is the Ctrl+A command that completely closes the throttle, although it's not intuitive and therefore not used.
The adhesion models (Davis A B C D etc) are difficult to set up and not everyone has the patience or knowledge/software to do this so the "correct" and "realistic" measures are omitted. In my experience I've found the use of them does little if nothing at all for my adhesion.
Perhaps if the casual OR user had been given every concievable tool to competently redesign their files things would be different.
A comprehensive eng/wag file optimizer as part of the OR package would be desirable to allow the most accurate use of the parameters.
Maybe it's worth looking at the requirement of a ReciprocatingMass parameter to simulate the total mass of inertia in the rotating parts themselves?
Remember: we ask if you can do it because we don't know how to do it.
#12
Posted 12 March 2022 - 06:15 AM
In fact, third number within throttle controller's definition refers the "speed" of regulator's movement...
However, that is NORMAL operation mode's speed.
@Jonatan
Unfortunately, Ctrl-A uses exactly thAt rate of regulator decrease now.
#13
Posted 12 March 2022 - 06:42 AM
Yeah - I've brought this up a number of times.
I've spent as much time as anyone trying to perfect steam locomotive performance with what's available in ORTS. I can't get anything that resembles what I've watched in RW videos of wheel slippage.
As Jonatan stated - all we seem able to achieve is zero to a million revs per second - there is no middle ground.
I'd really like to see some work done in this area - as managing wheel slippage seems to be a big part of steam locomotive operation - that we're currently missing out on.
Peter - if you have a locomotive tuned to represent realistic wheel slippage - please let us know - I'd be more than happy to take a look. Thanks for all your effforts.
Regards,
Scott
#14
Posted 12 March 2022 - 07:03 AM
Something I would like to see in the future for adhesion is having some local variations, perhaps through route editor being able to add the greasy bits where locos stand at platforms, or the odd wet or icy patch in a cutting.
In the old days, in this country, they used to cut all the undergrowth on cuttings and embankments every spring. In the years since they have stopped doing that, trees have caused a big problem every autumn. The juice from squashed leaves is far more slippery than rain or ice on the rails. This is the report of a serious accident caused by autumn leaf fall - Salisbury_Tunnel_Junction.pdf
#15
Posted 12 March 2022 - 07:22 AM
#16
Posted 12 March 2022 - 08:11 AM
Brandon
#17
Posted 12 March 2022 - 09:14 AM
ATSF3751, on 12 March 2022 - 08:11 AM, said:
This might be the case that the team (asuming they're mostly young people raised in our modern times) are more interested in contemporary forms of traction than steam and may resort to online data for the latter in leu of hands-on knowledge, which may not give an accurate picture of how it truly works as the data usually covers a specific part rather than the whole.
Very few people today truly know how to properly run a steam locomotive or how it should perform. My best bet would be to consult as many old timers as possible for input. A true steam engineer being shown the results in form of a video and review what is accurate and what isn't would be a great source of feedback for tuning the simulation.
Steam operation and wheelslip are governed by an infinte number of variables. Something as miniscule as the air moisture can affect the tractive effort.
#18
Posted 12 March 2022 - 07:37 PM
This could be potentially simulated by the fire mass rapidly dropping while the driving wheels slip, and the fireman (or the player when the AI fireman is shut off) will have to rebuild the fire mass back up to the ideal level.
...Not sure if this is worth implementing or not, but once we get the wheel slip itself figured out, then this could potentially be simulated.
#19
Posted 12 March 2022 - 10:58 PM
Jonatan, on 12 March 2022 - 06:06 AM, said:
The model does have inertia of mass included in it to calculate the angular acceleration (ie the speed of increase of the wheels). The above book is also used as a guide in calculating the inertia.
As always, I am happy to review this model if we can find some good physics references that describe how to accurately calculate the angular acceleration once uncontrolled slip has occurred, and some "worked" example calculations that we can use to compare the OR model to.
Jonatan, on 12 March 2022 - 06:06 AM, said:
The Curtius - Kniffler parameter is used to adjust the adhesion under "normal (non-slip)" conditions.
#20
Posted 13 March 2022 - 03:47 AM
Brandon
https://play.google....g=GBS.PP8&hl=en