[xavivilla]

I´m finding some problems testing a new steam compound locomotive eng file. It´s simple: I rewrite new phisics parameters recommended in Open Rails manual, following instructions suggested by "Coals to Newcasttle".
I test eng "behaviour" in Europe 1 route MSTS, and I can see in third group of lines, after push twice (Shift + F5), indicated power remains "0", with throttle close 90 -100% opening, and 25 - 30% cut-off forward. Locomotive runs, but speed decrease bit to bit, level field included. This is very irregular.
I think that "ORTSSteamLocomotiveType( Compound )" parameter is the problem. When I include this one in the same eng, without any other modification, I mean without parameters for ORTS, only with instructions for MSTS, indicated power remains in "0" value, and behaviour of engine is similar to first. If I change "Compound" by "Simple", locomotive with first configuration explained, "revive", and indicated power appears, raising with train run, as I suppose must be.
I have throught it´s possible had a new parameter with a second cut-off, like first real compound locomotives. But I can´t find it.
What is my, sure, mistake?

[copperpen]

The current OR steam compound model only uses one cut off control, but far as I am aware, the actual cutoff for the low pressure is different to the high pressure as per the real world. To use the compound you need to define the low pressure cylinders separately from the high pressure ones so the cylinder entry in the eng file looks like

NumCylinders ( 2 )
CylinderStroke ( 26.0in )
CylinderDiameter ( 15.0in )
LPNumCylinders ( 2 )
LPCylinderStroke ( 26.0in )
LPCylinderDiameter ( 25.0in )

so you have shown here two high pressure cylinders first and two low pressure cylinders second.

[xavivilla]

Note indicated power value 0, with locomotivie running. May it be a bug?

http://www.railclub.org/xavivilla/imagen/OR_Screenshot_Compound.png

[copperpen]

Ah. Now I see what you mean. Just tried the test Atlantic compound plus another compound and see the same thing. I wonder if it has any bearing on the apparent lack of power when running compounds.

[steamer_ctn]

xavivilla, on 25 March 2017 - 03:04 PM, said:

I think that "ORTSSteamLocomotiveType( Compound )" parameter is the problem. When I include this one in the same eng, without any other modification, I mean without parameters for ORTS, only with instructions for MSTS, indicated power remains in "0" value, and behaviour of engine is similar to first.

As suggested by Copperpen, a compound locomotive requires a HP and LP cylinder to be defined, otherwise it will only be a simple locomotive.

In regards to the IHP I will have a look at it.

Thanks for reporting it.

[Genma Saotome]

There remains a very important problem: Many compound locomotives are built with multiple .s files and each of those ./s files has its own .eng or .wag file. I don't think anyone can ever get the performance right in that situation no matter what kind of locomotive it is.

IMO the solution is to provide the means to use one .eng file for the assembly of one locomotive from several .s files. That would result in one .eng file so everything related to power, weight, etc. etc., is one place as it it should be. I don't know if the .fa method would work or whether something new needs to be done (the likely gotcha here is bogies appearing in different .s files). But until that problem is fixed there are a whole lot of locomotives whose performance will remain completely funky at best.

[copperpen]

That is something I suggested some time ago, but at that time it gained very little support. The same would apply to all multi part model locomotives where the power is split among several parts of what in real life is a single unit. Articulated steam both simple and compound, the Milwaukee boxcabs and the Baldwin Centipedes come to mind for starters.

[RTP]

About one year ago, I proposed:

"Add in the wagon section of the loco.eng:

ORTSCarriages (
(
Pivot ( x.x y.y z.z )
Shape ( "shape.s")
ShapePivot ( x.x y.y z.z )
Flip ( 0 )
)
(
Pivot ( x.x y.y z.z )
Shape ( "othershape.s")
ShapePivot ( x.x y.y z.z )
Flip ( 1 )
)
)

Where x.x <> 0.0 allows for some lateral displacement.
That is useful for three trucks locos, where the central one have this movement.
"

Perhaps this proposal needs more discussion, but is a solution for most of the articulated locos, steeamers, electrics or diesel.

Regards.

[xavivilla]

Sorry, but i´m talking about Compound locomotives, not articulated. In my case, studing 242 A1 of Mr. Chapelón. I think you know this real prototype. It is very sad look the HUD of this engine and verify "0" value Indicated power, with locomotive running. This is the cause I think we are finding with a bug, for compound locomotives in general.
And I propose another question: Really do you think is the indicated power well calculated in modern steam locomotives? In this case, appears in HUD 2394 kW calculated power, but this engine had a performance of 3560kW. Not maximun, of course.
Well, you can see there are some new questions to discuss...

[copperpen]

Both items are under investigation. I also realise that you are not referring to an articulated locomotive, but this is a forum for discussion, and discussions do sometimes diverge from the original subject.