[copperpen]

Second run and I can now see that both maximum and actual generation figures are affected by this parameter, but responsiveness is not. One thing I would like to see though is a relaxation of the upper clamp because some engines were capable of producing more steam than the code allows. Currently, the only way to achieve that is to increase the heating surface area.

[Gehe]

You are right the parameters changes the steam production . In one of my .eng there was still the spelling mistake and therefore no effect visible.

I also agree with your proposal to relax the upper limit of 15.0 since it corresponds to a value of about 73 kg steam per hour and sqm evaporation area. Some locomotives are capable to avieve values in the 80s or even up to 100 kg/hsqm.

Another topic which I found is the temperature of the superheated steam. All data I have show that locos with a superheater area of about 45-50% of the evaporation area achieve values between 350 - 400 °C. The model gives here values about 290 °C. To get higher values you have to increase the superheate area. I do not know if the model uses this temperature for the calculation, if yes this part of the model should be checked if all assumptions made are correct.

The different power values given also confuse me a bit. Normally you have the power measured in the cylinders the indicated power (IHP). If you subtract the friction of the loco you get the power at the drawbar.

If you look into the locomotive information the power at the drwabar given there is correct. But the IHP shown there is just the power at the drawbar plus the power used to accelerate the loco. At constant speed both values are equal. The power related to the tractive effort which is shown in the upper part of the page is according to my opinion the real IHP, since it shows the power which is provided by the machine in the cylinders before applying any friction.

In general after my first tests I like the steam model it provides reasonable results. For the tests I use Special wagon with high friction which make it easy to do tests at constant speed and high load like the tests done in reality.

[copperpen]

The work on the Steam model was done based on test plant data from two locomotives, one from the US in the early 1900s, and one from the UK in the mid 1900s. The US one was saturated and the UK one was superheated. It may be that the superheat tables do not go high enough to cater for high superheat areas.

[Gehe]

In the meantime I did more tests with steam locomotives to better understand the steam model and the values displayed in the HUD.

I was a bit confused about the different power values. The power at the drawbar was pretty clear but the difference between the indicated HP and the power shown in the HUD above were unclear for me and I did some misinterpretations. A look into the source code was helpful. The IHP is the "real" IHP based on the pressure and the number and geometry of the cylinders. The value shown in the upper part is the IHP just multiplied with the parameter ORTSCylinderEfficiencyRate which is used to customize engines.
This allows adaptations to match the characteristics of a specific loco. The simple approach to multiply the tractive force with this factor makes it easy on one side on the other side it leads to results which are partially not realistic. E.g. if you apply a factor >1 because the loco has a better steam consumption than the one on which the steam model is based on you get changed values for all speeds. At speed zero you obtain then a higher starting tractive effort despite the fact that at very low speeds just the cylinder geometry defines the tractive force. As speed increases the influence of the design of pipes valves,etc increases.

I would propose that there will be an upgrade in a later OR release by introducing a table which contains speed dependent ORTSCylinderEfficiencyRate values. The allows to do a more realistic customization of a loco.


Gehe