[steamer_ctn]

copperpen, on 23 February 2017 - 06:17 AM, said:

I have at last been able to devote some time to testing the steam compound model. While the Woolfe system is a simple one to model, it was not used by most engineers who dallied with compounding. The Woolfe system operates by direct admission from the HP cylinder/s to the LP cylinder/s. Most rail applied compound systems used an LP receiver between the HP and LP, and there were also various systems used to admit small amounts of HP steam to the LP cylinder/s while starting, usually switched off after a couple of turns on the driving wheels. It would be good at some time in the future to see this type of system modelled.

As all the steam locomotives in OR are modeled with their relevant "indicator cards" to determine the MEP, this particular compound type appeared to be the easiest to model with the most amount of information available about it (see pg 25 of this document). It also appeared to be the "most common". Therefore given the variety of compound locomotives built for "testing", and the fact that most of them didn't appear to be very popular in service, only the Woolfe model was coded. I was also able to find test reports for this type of model, so a comparison of the code and the model could be done.

copperpen, on 23 February 2017 - 06:17 AM, said:

Turning now to my actual testing, The model is good and does work remarkably well in most respects. I do suspect though that there is a tiny bug in there. With both models used for testing I have noticed that somewhere between 63 and 64 mph, the steam usage goes into reverse. This was observed in both the ctn_test_atlantic_compound and an LMS compound 4-4-0 I have set up. In both cases the reverser was at 40% and throttle was at 100%. As speed increases, usage continues to fall, slowly with the test atlantic, faster with my test 4-4-0. In fact with the 4-4-0, usage has dropped from 11800lb to 10100lb between 63 and 79mph and continues to fall.

I will try and have a look at it, but I have a number of other activities on the go at the moment.

Thanks

[copperpen]

steamer_ctn, on 23 February 2017 - 12:33 PM, said:

As all the steam locomotives in OR are modeled with their relevant "indicator cards" to determine the MEP, this particular compound type appeared to be the easiest to model with the most amount of information available about it (see pg 25 of this document). It also appeared to be the "most common". Therefore given the variety of compound locomotives built for "testing", and the fact that most of them didn't appear to be very popular in service, only the Woolfe model was coded. I was also able to find test reports for this type of model, so a comparison of the code and the model could be done.
Thanks

There were substantial numbers of compound locomotives built during the years from the late 1800s through to the 1950s, many of which were not of an experimental or testing nature. Some remained in service for a good number of years without any major modification. Popularity in service is a subjective phrase. Some of these were built in substantial numbers, over 9000 in one case.
The Vauclain compound based on the old woolf system with no receiver was probably the most common in its time period in the USA, but after about 15 years no further locomotives of this type were built for use in the USA. Page 25 of that document actually refers to a 2 cylinder receiver type compound. Diagram 25 on page 57 is in fact the cylinder diagram of a Woolf type compound. I feel that there is probably enough in that document to code a receiver type compound at some point in time which should be adequate for all locomotives of that type, in the same way that the existing simple expansion code works for all locomotives of that type without reference to indicator diagrams for a specific class.

[Hobo]

Ares there any developments being made on articulated steamer " engine file structure " such as BigBoy , challenger , Virginian , and some mallets like the Sumpters ?

[copperpen]

It is something that has been raised a couple of times, but not met with much debate. It is a requisite though to enable compound operations of those two part engines, three in the case of the Triplex. Don't forget there are other articulated types that have been modelled with two engine sections.