ORTS Davis Numbers UoM - need OR developer verification, please

[R. Steele]

I think this research proves that the OR Davis numbers default UoM are as shown in the manual, and do not need to be specified, as has been shown in other posts. Subject to verification by an OR developer!

A --- N (Newtons), will accept lbf if specified
B --- Nm/s, will accept lbf/mph if specified
C --- Nm/s^2, will accept lbf/mph^2 if specified

Everything written in the manual points to using FCalc 2.0 with Metric Units as the operating UoM for Davis calculations.
Changing UoM is drop down under File...there are two choices Metric and US units.
Traditionally in MSTS metric units have been used...Mass of wagons and locomotives is the simplest example, others abound.
Most pointedly metric units are listed first in the Recommended Units column, typically this means preferred and/or default, at least in all the manuals that I used in my life. I prefer the default UoM to be explicitly stated and whether it needs to be included in the data.
Look at the screenshot shows my reasoning.
Shown is the manual, Peter Newells most excellent site (folks you really should read this stuff...all of it.) and the two examples of FCalc2 in both operating UoM. They match Peters conversion utility exactly.
So if you have Metric Units set as the operating UoM in FCalc2 I believe you are good-to-go, just copy the Davis numbers and use in OR, no need to specifically state the UoM. Choosing US units, would be perverse logic and just add more work to an already onerous task.
No need to diminish your fun...
bandicam 2017-11-05 11-19-21-972.jpg

[baldwin]

As a tester, I have never specified the Davis UoM, taking them from Fcalc in metric mode.

[R. Steele]

Your perspective is encouraging.
This questioning started in this thread (especially Marek post #4 ) http://www.elvastower.com/forums/ind..._1#entry227834

Then there was a payware release of OR only models that only used lbf as a UoM suffix in the Davis numbers, it logged errors in OR.
So I started looking for some sort of proof...verification from a developer or someone with understanding of the code would be welcome.

[R. Steele]

steamer_ctn (Peter Newell) provided this response to the same question posted at ET

The default units are indeed the METRIC ones, and typically do not need to be included in the parameter when inputting them into the ENG file.

Recently I have been doing some work with a UK group of modellers testing steam locomotive configurations, and one of the things that has become very apparent is the wide variety of resistance formulas that abound. Typically they all take the same form as the Davis equations, ie A + BV + CV2

The setting of an accurate resistance value (as much as possible) is important as it will impact upon the performance of the locomotive.

Happy researching.