Changing Safety Valve Volume Level

Robert2d6 said:
This is the engine spec that is in that loco kuid , prior to modification by me.


https://www.auran.com/TRS2004/DLS_viewasset.php?AssetID=235938
Click to expand...


I've used that engineconf. It's one of the better ones, less inclined to pop off.

Thing is, I can't imagine a boiler existing in the real world that was twice the size of a Y6b Mallet's boiler in terms of volume. That just seem highly improbable. One of these files is using values that are off.


Can someone post the formula for computing boiler volume? That's not something you would normally find listed for a given U.S. steam locomotive. Is there a source somewhere for this data? If so, it should just be a matter of looking up a similar sized boiler to the USRA 2-8-8-2 and Y6b and figuring out what the value should actually be.

Looking at the Auran "Big Boy" values, I see it's also using boiler-volume=40, the same value used for the USRA 2-8-8-2. Maybe they just made the value up(?)
 
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Robert2d6 said:
I think you have these inverted as to which is undersized, the one that I posted is the smaller of the amounts that you have listed as y6b. That is the settings for the USRA Espec Kuid.
Click to expand...

I might have swapped the figures. But it really doesn't matter. One is about twice the value as the other. "That just ain't right." A real N&W Y6b and a real USRA 2-8-8-2 would have been about the same in terms of boiler volume and most other values. You can see for yourself -- this page has the data for the N&W Y3a (USRA) and Y6b Mallets.



One
 
Azervich said:
Hi Robert,

Try change these values too as they've been set for maximum heat, my values will cause the boiler to slowly build pressure.

boiler-efficency 0.861
boiler-efficency-min 0.454
boiler-efficency-idle 0.667

If safeties still keep popping and staying on keep increasing boiler-heat-loss, most of my steam locomotives are rated from 120PSI to 140PSI with a very few from 160PSI to 175PSI boilers, so my values are based for those pressures.

Cheers.
Click to expand...

We are on the right track. I changed these values, went over 5 miles, including a stop to let an AI train go by for about 2 minutes, and a speed averaging 15 mph, and the safety valve was as quiet as a church mouse the entire way. Here is what I wound up with for engine spec settings.

USRA 2-8-8-2 TS12 Loco Kuid <kuid2:243294:1299:2>
Engine spec Kuid <kuid2:243294:1317:2>

Modifications to Engine spec in red.
steam


{
number-cylinders 2
number-power-strokes 2
firebox-heating-surface-area 31.99
boiler-volume 21.87
steam-chest-volume 0.6413
steam-chest-max-flow 240.09
max-fire-temperature 790
min-fire-temperature 600
initial-boiler-temperature 470.2
max-coal-mass 1215
ideal-coal-mass 608
shovel-coal-mass 24.3
safety-valve-low-pressure 1773
safety-valve-high-pressure 1809
safety-valve-low-flow 5.13
safety-valve-high-flow 15.4
water-injector-rate 8.48
piston-volume-min 0.015048
piston-volume-max 0.316015
piston-area 0.5361
burn-rate 1.026
burn-rate-idle 0.01026
speed 17.88
boiler-heat-loss 0.85
blower-max-flow 0.203
piston-angular-offsets 0.1,0.8854,1.6708,2.4562
firebox-thermal-conductivity 17
firebox-plate-thickness 0.019
super-heating-constant 100
firebox-efficiency 0.9
blower-effect 0.2
boiler-efficency 0.761
boiler-efficency-min 0.454
boiler-efficency-idle 0.667
valve-lap-percent 0.1
cutoff 0.55
hand-brake-max-force 5.9



Now anyone can download this loco from the DLS, which already has the engine spec in it, and then modify the engine spec. You have to remember every time you make a change in the engine spec, you have to delete the loco in your session and reinstall the loco in the session, before the new spec will take effect. After that, you can just load the same loco into any session. The silence from the safety valve is wonderful. In fact, in this screen shot about 6 miles out, I was waiting for an AI loco to pass, and it was going PHTRT..PHTTT PHHHTTT..PHTTTT PHTTT, and my loco was not making a peep. I could hear my fireman saying" I wonder who the jerk is in that loco"??????? :hehe:


robert2d6_20121215_0000_zps70ced048.jpg
 
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Comparing a few engineconfig files on the DLS -- going from small to larger -- for similar or identical boilers, the value used for boiler-volume seems to vary greatly. Wonder which ones are bogus?


USRA 2-8-2 (should be a little smaller than the 4-8-2/2-10-2 boiler and 2-8-8-2 boiler)


USRA light 2-8-2 e-spec TS12

boiler-volume 10.92


e-spec TS09/10 2-8-2 USRA Light Mikado

boiler-volume 17.24


USRA 2-10-2 and 4-8-2 (the real locomotives had boilers of nearly identical size -- should be big than the 2-8-2 but smaller than the 2-8-8-2 boiler)


e-spec TS09/10 2-10-2 USRA Light Santa Fe

boiler-volume 25.826


e-spec TS09/10 4-8-2 USRA Light Mountain

boiler-volume 24.5


USRA Light 2-10-2 E-spec TS12

boiler-volume 12.77


USRA light 4-8-2 e-spec TS12

boiler-volume 11.78


USRA 2-8-8-2 (should be a little larger than the 2-10-2/4-8-2 boiler)


USRA 2-8-8-2 e-spec TS12

boiler-volume 21.87


e-spec TS09/10 2-8-8-2 USRA

boiler-volume 37.93


N&W Y6b 2-8-8-2 (should be a little larger than the USRA 2-8-8-2)

N&W Y6B Engine Specification

boiler-volume 40
 
wva-usa said:
Comparing a few engineconfig files on the DLS -- going from small to larger -- for similar or identical boilers, the value used for boiler-volume seems to vary greatly. Wonder which ones are bogus?


USRA 2-8-2 (should be a little smaller than the 4-8-2/2-10-2 boiler and 2-8-8-2 boiler)


USRA light 2-8-2 e-spec TS12

boiler-volume 10.92


e-spec TS09/10 2-8-2 USRA Light Mikado

boiler-volume 17.24


USRA 2-10-2 and 4-8-2 (the real locomotives had boilers of nearly identical size -- should be big than the 2-8-2 but smaller than the 2-8-8-2 boiler)


e-spec TS09/10 2-10-2 USRA Light Santa Fe

boiler-volume 25.826


e-spec TS09/10 4-8-2 USRA Light Mountain

boiler-volume 24.5


USRA Light 2-10-2 E-spec TS12

boiler-volume 12.77


USRA light 4-8-2 e-spec TS12

boiler-volume 11.78


USRA 2-8-8-2 (should be a little larger than the 2-10-2/4-8-2 boiler)


USRA 2-8-8-2 e-spec TS12

boiler-volume 21.87


e-spec TS09/10 2-8-8-2 USRA

boiler-volume 37.93


N&W Y6b 2-8-8-2 (should be a little larger than the USRA 2-8-8-2)

N&W Y6B Engine Specification

boiler-volume 40
Click to expand...

What effect would changing the boiler-volume produce on engine operation? Larger would take slower to heat up, but take longer to cool? What else?
 
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Robert2d6 said:
What effect would changing the boiler-volume produce?
Click to expand...

In the real world, the capacity of the boiler was one of the primary factors that determined how many cars a locomotive could pull and how fast it could pull those cars. If you replaced a (real) USRA 2-8-8-2's boiler with a boiler about half that size, say a tiny little early-1900s 2-8-0 boiler, and then tried to pull a long train with that altered locomotive what do you think would be the result?

If boiler-volume isn't one of the critical factors in the so-called "physics" simulation used in Trainz it certainly should be...

I would think it would be important to use the correct value for boiler-volume. If this is truly based on science, then there is a "correct value", I assume...

 
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The trouble with the enginespecs is that they use parameters that aren't available.
I think they could do with a total rewrite based on readily available data as all this guesswork makes a mockery of the whole idea.

Chris.
 
chrisaw said:
The trouble with the enginespecs is that they use parameters that aren't available.
I think they could do with a total rewrite based on readily available data as all this guesswork makes a mockery of the whole idea.

Chris.
Click to expand...

So is that what's going on? There's no source for the data, and no reliable formula for determining a fairly accurate figure to use for a given value?

I just picked out boiler-volume to get an idea of whether or not there was any semblance of consistency to the values being used in the engineconfig files for the medium to large U.S. locomotives. After looking at the other "steam containers", such as max-coal-mass or firebox-heating-surface-area, etc., I'm finding those values vary greatly for the exact same locomotive or locomotives of about the same size.

I get the impression that the Trainz European locomotives are probably based real-world data, but the values used for U.S. steam are based primarily on guesswork(?)

If so, is there really any mystery why safety valves are running amok on many of the U.S. locomotives?
 
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To get a reasonable figure for boiler volume I use PEV's attachment maker, however this does not work with Ben's locos because you do not get a wire frame view. As an example for another boiiler about the same size. Open for edit, open PEV's attachment maker and load the main.im file. On the horizontal frame place the cursor on the rear of the boiler and read off the Y axis position. The one I used gave a reading of 4.734, then move the cursor to the front of the boiler (not the front of the smoke box) this reading was -6.746. Remembering that positions are set from the centre you have to ignore the negative and add the two figures, so 4.734 + 6.476 = 11.21m. Do the same on the end facing frame to get the X axis, in this case x = 1.085 at the right side of the boiler, so 1.085 x 2 = 2.17. This gives me a boiler size of 11.21m long by 2.17m dia. So to get the volume 2pi * r * l = 6.284x1.085 = 6.818 x 11.21 = 76.431
then to get the boiler half full I divide that by 2 = 38.21. Then it can be reduced further to account for the space taken up by the Boiler tubes.
These dimentions are what I found for the Y6b not for the USRA 2-8-8-2.
Note: I did not add any attachment points when doing this, only used the cursor to find relative positions.

I have also modified The USRA 2-8-8-2 since it was uploaded so if anyone want's it drop me a PM. I find refining the performance of a given loco is a contiuing process, as I learn more about things I impliment them in my favorite locos.

Cheers,
Bill69
 
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Bill69 said:
To get a reasonable figure for boiler volume I use PEV's attachment maker... (stuff deleted)
Click to expand...

I have elevation drawings of the Y6b so its a lot easier/quicker to simply take a measurement from the drawings.

This gives me a boiler size of 11.21m long by 2.17m dia.
Click to expand...

Your dimensions seem in the ballpark, if you're measuring all the way back to the cab. But by doing so you're also including a large section of the firebox (see loco cutaway view below).

So to get the volume 2pi * r * l = 6.284x1.085 = 6.818 x 11.21 = 76.431
then to get the boiler half full I divide that by 2 = 38.21. Then it can be reduced further to account for the space taken up by the Boiler tubes.
These dimentions are what I found for the Y6b not for the USRA 2-8-8-2.
Click to expand...

I'm not following the logic of your math. At all.

2pi * r will get you the circumference of a circle. Multiplying the circumference by height, as you did, gives you the area of a cylinder.

If you're trying to determine the volume of a cylinder, which I assume you are since the Trainz wiki says boiler-volume="Physical volume of boiler in litres", then the formula I was taught to determine the volume of cylinder is Radius x Radius x Height x Pi. Using that formula I arrive at a very different end result than you did.

The thought that 38.11 (liters) is the volume of water a Y6b boiler held seems rather bizarre to me, because that would mean that a Y6b boiler held less water than a standard U.S. 55-gallon (208.198 liter) drum would hold. Therefore, I'm going to assume the Trainz wiki info is incorrect and that boiler-volume is something other than "Physical volume of boiler in litres"(?)


Cutaway view of C&O Class G-8 2-8-0 locomotive
800px-CO_Class_G8_2-8-0_Locomotive_Cutaway_View.jpg
 
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The answer to the calc above is not volume it is metres^3 I guess I should have said that. I have found this is the best figure to use in Trainz.

The amount of water in litres is of no use in Trainz, it is only the percentage of water that matters.

If you want to convert that to litres it's 38,210L 8405 Gal UK 10094 Gal US

Cheers,
Bill69
 
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Bill69 said:
The answer to the calc above is not volume it is metres^3 I guess I should have said that. I have found this is the best figure to use in Trainz.

The amount of water in litres is of no use in Trainz, it is only the percentage of water that matters.

If you want to convert that to litres it's 38,210L

Cheers,
Bill69
Click to expand...

Then the Trainz wiki info is totally incorrect. It's not volume, but the area of boiler (in meters, not liters). Is this correct? It's called "boiler-volume" but it's not really volume at all. (Which makes little sense.)
 
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Ok I had one word wrong in the above post, it is WATER volume is in percent. Forget about litres in a steam engine, the only time you need to work out the litres is for the tender.

2*pi*r*l if all measurements are in metres the result is in metres^3

Cheers,
Bill69
 
I use the locomotive loaded and unloaded mass to calculate boiler volumes, here's an example

40ton 508kg Loaded
37ton 558kg Empty

2ton 950kg Load

180kg Ideal Coal
80kg Driver
80kg Fireman
unknown kg Sand (lets just say a couple of kilos)
2610kg Boiler Water Volume 99.9%

Which is 2.610m3 or 2,610 litres when hydro pumped, 1m3 = 1,000 litres so you could still calculate boiler using litres and kilogram as 1 litre = 1 kilogram.

EDIT:

Hi wva-usa,

I think that's the old TS2004 config which is in litres for boiler and cylinders, TC3 changed to cubic metres and squared metres.

Cheers.
 
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Azervich said:
Hi wva-usa,

I think that's the old TS2004 config which is in litres for boiler and cylinders, TC3 changed to cubic metres and squared metres.

Cheers.
Click to expand...

When you search for "boiler-volume" at the Trainz Wiki the old (incorrect) page comes up higher in the results than the new (correct) page. So the result is total confusion since the page you find (first) doesn't mention that fact that it's totally out of date.
 
Bill69 said:
So to get the volume 2pi * r * l = 6.284x1.085 = 6.818 x 11.21 = 76.431
then to get the boiler half full I divide that by 2 = 38.21.
Click to expand...

(Sigh) I guess we'll have to agree to disagree, because where I live the volume of cylinder = pi × r [SUP]2[/SUP] × h.

Using your figures: 3.14 x 1.085 x 1.085 x 11.21 = 41.437613665

But apparently I'm mistaken and so is Wikipedia and so are all of the online calculators.

(I give up.)

Good night.






 
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