Curtius Kniffler Adhesion parameter
#1
Posted 25 July 2021 - 02:59 AM
Some help is needed here. How do we set this parameter?
Do we apply to all traction units steam locomotive, diesel (electric, hydraulic, mechanical) locomotive, electric locomotive, steam railcar, diesel or petrol (electric, hydraulic, mechanical) railcar, electric multiple unit?
Where do we find the real life information needed to correctly set this?
How do we change that information into OR entry?
What if we can not find relevant data? Will OR give a good estimate? Is there a way that we can estimate?
Which types of traction are likely to be most or least influenced by relying only on default values?
If it is concerned with 'adhesion' should we also adjust for carriages, wagons, tenders and driving trailers? Will at affect braking as well as tractive force?
#2
Posted 25 July 2021 - 03:18 AM
I have never heared about Kurtis-Kniffer formulas before I read ORTS manual.
We will need the methods of converting one units to another?
Why can't adhesion be derived from common parameters of *.eng-files as tractive mass, area of wheel-to rail contact (related to wheel diameter), coefficient of adhesion (related with wheel and rail material, corrected to track inclination, ambient temperature and humidity later) and current tractive effort, speed?
http://www.elvastowe...el-locomotives/
Related topic
#3
Posted 25 July 2021 - 01:02 PM
It really is not that hard to construct a spreadsheet calculator for the CK numbers ... I believe there are one or two here in the library --- or attached in one of the threads.
FCalc2 can be downloaded here or at TS.
#4
Posted 25 July 2021 - 01:14 PM
At 2006 I used Fcalc just once.
It takes in account air resistance as well.
#5
Posted 25 July 2021 - 01:27 PM
#6
Posted 25 July 2021 - 01:43 PM
#7
Posted 25 July 2021 - 02:24 PM
darwins, on 25 July 2021 - 01:27 PM, said:
Whoops, sorry.. it's Sunday & I've relaxed with too many http://www.elvastower.com/forums/public/style_emoticons/default/cheers3.gif I'm starting the mix up resistance & adhesion! Sorry
So to clarify -- some links for CK values
OR Manual-Physics
Traction Paper with CK formula
Paper with General Equations
GitHub Paper on OR Physics
The default CK values ( ORTSAdhesion ( ORTSCurtius_Kniffler ( 7.5 44 0.161 0.7 ) ) will work for everything up to the modern locomotives...AFAIK that's where calculating new values would be of benefit...rule of thumb ( so I've been told ) is anything newer than SD40-2s.
I've included CK values ( where applicable ) with version2 of the Std_Eng files...I used Joe Realmuto's Curtius_Kniffler calculator to obtain the numbers. A Public Domain utility to calculate these values would be useful to the community.
#8
Posted 25 July 2021 - 03:36 PM
R H Steele, on 25 July 2021 - 02:24 PM, said:
Remove the Dash-2 from that statement and it's good advice. The HT-C has significantly greater adhesion than the flexible SD truck*. Bear in mind, also, that most EMD units of yesteryear have been retrofitted with newer wheelslip control modules, so they get considerably better traction than they would have out of the factory. Many of them have the same or equivalent microprocessor wheelslip control modules as current locomotives (although they lack ground radar, meaning detection speed is lower and thus they are incapable of wheel creep).
*Since retconned with the name "Flexicoil," a term that doesn't appear in EMD materials until the 1980s
#9
Posted 25 July 2021 - 04:43 PM
ErickC, on 25 July 2021 - 03:36 PM, said:
*Since retconned with the name "Flexicoil," a term that doesn't appear in EMD materials until the 1980s
Thanks Erick, of course, makes sense. I really don't know if OR will ever be able to code&implement all the variations, retrofits, and subtleties found in the real world. The idea of modeling ground radar is intriguing, is it not?
#10
Posted 25 July 2021 - 07:20 PM
R H Steele, on 25 July 2021 - 04:43 PM, said:
I don't see a problem, we already have a variable for speed, we can use that as the radar generated speed.