This is very exciting.If I had one complaint, I would appreciate it if you could operate the throttle in stages (for example, Vanilla). (Sorry, I'm writing this using Google Translate)
Sorry for the layman's question - just interested in a detailed answer:
What effects would an increased boiler pressure have? More total tractive effort I could deduct - more pressure on the same cylinder area and all that - but are there any other changes? For a given cutoff, does higher pressure extract more energy and work from a given amount of coal and/or water?
I'm not entirely sure, since I'm not great at physics. Here's what I think:
For a given cutoff, the higher pressure will increase power, but also increase the exhaust pressure (i.e., the steam exiting the piston is still pretty high pressure and is being wasted). It seems to me that if you are running as close to center on the reverser as you can for efficiency, it should be more efficient (the power you used to get at 75% cutoff, you can now get at 40% cutoff or whatever). It's not that the coal and water are providing more energy; it's that you're using less steam (the average mass flow rate of steam is less because the cutoff is lower).
There are also some details with the specific enthalpy increasing with pressure (i.e., heat energy per pound of steam increases with pressure). I think this might make the locomotive a little more efficient at high pressures, but this is the bit where I'd need to take a thermodynamics class to understand what's happening. But for the pressures we're talking about, the specific enthalpy of steam doesn't seem to change too drastically and the effects of the change in cutoff would presumably be more prominent.
This thing rules. One thing needs to be changed. For the dome throttles that the steam engines are equipped with, the steam flow needs to be delayed. IF a front-end throttle was present, the delay would be rendered non-existent.
The core issue is that the S282's model is much older than the simulation code. When Altfuture was working on the Simulator update, they realized that the S282 was too inefficient unless they added superheater simulation. But they also didn't want to model the throttle lag, so they simulated a front end throttle. So they prioritized balancing the game over making the simulation match the visuals of the S282 model.
I chose to keep this; I wanted to stay with Altfuture's vision of what the S282 is (vaguely an S200, superheated, front end throttle). As I mentioned in the mod description, there are locomotives with internal front end throttles, so what Derail Valley has is technically not impossible... I know it's very rare though.
I don't model any lag on either steam locomotive (IIRC unrestricted pressure changes in gas move at the speed of sound). But I do model the mass flow rate limit of the throttle valve, and I use the estimated volume of the branch pipes to determine the steam chest pressure.
TLDR, yes the S282 has a front end throttle. The S060 has a dome throttle, but it doesn't have a superheater, so it has a bit of lag but not a lot.
The steam entering through the regulator and trying to keep the pistons moving is wonderfully realistic. The coupling process is now thrilling. It is now more enjoyable to operate at low speeds.
11 comments
(Sorry, I'm writing this using Google Translate)
What effects would an increased boiler pressure have? More total tractive effort I could deduct - more pressure on the same cylinder area and all that - but are there any other changes? For a given cutoff, does higher pressure extract more energy and work from a given amount of coal and/or water?
For a given cutoff, the higher pressure will increase power, but also increase the exhaust pressure (i.e., the steam exiting the piston is still pretty high pressure and is being wasted).
It seems to me that if you are running as close to center on the reverser as you can for efficiency, it should be more efficient (the power you used to get at 75% cutoff, you can now get at 40% cutoff or whatever). It's not that the coal and water are providing more energy; it's that you're using less steam (the average mass flow rate of steam is less because the cutoff is lower).
There are also some details with the specific enthalpy increasing with pressure (i.e., heat energy per pound of steam increases with pressure). I think this might make the locomotive a little more efficient at high pressures, but this is the bit where I'd need to take a thermodynamics class to understand what's happening. But for the pressures we're talking about, the specific enthalpy of steam doesn't seem to change too drastically and the effects of the change in cutoff would presumably be more prominent.
I chose to keep this; I wanted to stay with Altfuture's vision of what the S282 is (vaguely an S200, superheated, front end throttle). As I mentioned in the mod description, there are locomotives with internal front end throttles, so what Derail Valley has is technically not impossible... I know it's very rare though.
I don't model any lag on either steam locomotive (IIRC unrestricted pressure changes in gas move at the speed of sound). But I do model the mass flow rate limit of the throttle valve, and I use the estimated volume of the branch pipes to determine the steam chest pressure.
TLDR, yes the S282 has a front end throttle. The S060 has a dome throttle, but it doesn't have a superheater, so it has a bit of lag but not a lot.
The coupling process is now thrilling. It is now more enjoyable to operate at low speeds.