[steamer_ctn]

Work is now nearly complete on revisions to the steam code.

The code changes have been verified and confirmed by testing a number of locomotives against performance test reports that have been able to be sourced. There is a desire to obtain additional reports if possible so that further locomotives can be tested against the code. So if anybody can help with this that would be great.

Tuning a locomotive against a test report similar to the ones identified above is relatively easy as the required configuration parameters are all supplied. However when a locomotive does not have a test report it is more of a challenge. Over the years good work has been done by various contributors to assist modellers in setting up steam locomotives using standard Rules of Thumb (RoT).

The steam module in Open Rails uses an approach were it attempts to cater for modellers who don't wish to spend a huge amount of time tuning their model. It also allows for modellers who wish to achieve a more realistic physics for their model. OR is therefore based upon a BASIC and ADVANCED configuration approach, as follows:

BASIC – standard locomotive design parameters without addition of any ADVANCED parameters.

ADVANCED – one or more of the ADVANCED configuration parameters (as referenced on CTN website) will be used to tune the locomotive as close as possible to the relevant locomotive test.

In the BASIC configuration mode, standard generic reference values (or RoT) are used by OR to initialise the locomotive at start. As can be seen by quickly reviewing some of the graphs shown on the CTN ADVANCED parameters page, there can be a wide variation in some of the defining parameters. These defaults should allow "most" locomotives to achieve a "reasonable" performance standard provided they are driven within acceptable bounds of operation.

However for those who are interested in achieving a closer physics representation for their model, a proposed tuning process is being suggested for locomotives which do not have know test reports available. It uses information that hopefully can be sourced a lot easier then a test report. This information is used define a test standard, and the model configuration settings are then "reverse engineered" and tweaked to achieve the required performance standard. It relies upon information generally found in load tables, and working timetables.

The attached document describes the proposed test process and uses the flow chart (also attached) to identify parameters which may need changing.

If would be good if there are any interested modellers who would like to test the process and have a go at tuning a locomotive, and then provide feedback on the process.

Thanks

Attached File(s)

•  flow_chart_v2.pdf (107.47K)
  Number of downloads: 369
•  Steam Locomotive Tuning_v2.pdf (81.45K)
  Number of downloads: 304

[James Ross]

steamer_ctn, on 21 November 2017 - 07:14 PM, said:

Work is now nearly complete on revisions to the steam code.

Great work! :sign_thanks:

When you get a minute, please set the blueprint "Implementation" to "Implemented" and I'll tick off the item on the roadmap.

[steamer_ctn]

Hi James,

James Ross, on 22 November 2017 - 12:51 PM, said:

When you get a minute, please set the blueprint "Implementation" to "Implemented" and I'll tick off the item on the roadmap.

I will do once fully complete.

[steamer_ctn]

To finish off the development of a tuning process, the test team would like to obtain some performance points for a US steam locomotive.

Ideally the following information is required:

• Grade that locomotive is climbing
• Load behind the locomotive
• Speed of train

This information could be ascertained from a working timetable for a specified running time on a particular section of track. Ideally the section of track should have a long ruling gradient in it. The load specified for the locomotive should also be provided. Preferably it would be good if the relevant documents (or extracts) can be provided to the team, perhaps via PM.

Is anybody able to assist with some potential examples?

Thanks

[Lindsayts]

The book by Weiner "Articulatred Locomotives" has this info for some machines, some include coal and oil and water consumption. I will have a look and put up some details.

Lindsay

[systema]

Further enhancements have been made to the Steam Locomotive code and very accurate reproduction of performance against known test data results has been replicated with the Advanced versions of two locomotives.

Two models on the CTN website have been updated. These are the LNER/British Rail B1 4-6-0 and the LNER V2 2-6-2 locomotives. The British Rail Mk1 coaches to go with these have also been updated to more accurately reflect the weights of these coaches.

In order to achieve accurate performance, the resistance of the rolling stock also has to be accurate. The British Rail Report for the Standard 71000 locomotive gives resistance curves for the Loco + Tender and an unspecified 32t Mk1 Coach. A Modified Davis Formula has been used to replicate these curves and a calculator for resistance is available with the V2 download. This enables accurate calculation of ORTS Davis Numbers for various pieces of steam era stock. Canadien National and SNCF calculators are also provided for use with more modern stock.

A full explanation of the tuning details and performance results is also provided with each model.

The revised items of stock include updated Vacuum Braking parameters which provide realistic performance. Thanks to Darwin Smith for providing the information on these.

In addition the locomotives and coaches have all the latest available steam effects which include steam heating hose leaks, injectors and forward and rear cylinder cock steam.

Mick Clarke
MidEast Plus

This post has been edited by systema: 03 May 2018 - 10:33 AM