Re: Steam Physics

Have you given it a go? Post your experiences, particularly things that worked well. Let the team know what works and doesn't work as they cannot test the software with every combination of routes, activities and content available for MSTS. OpenRails is actively being improved and is quickly approaching v1.0. This is a great place to discuss what you can do with OpenRails.

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Re: Steam Physics

Postby copperpen on Tue Mar 14, 2017 2:58 pm

@Darwin
I have your compound files. Will see how they perform.

@Mick
I have your 71000 test files, but no test program so it seems I will sit this one out.
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Re: Steam Physics

Postby systema on Tue Mar 14, 2017 3:11 pm

Loco and Tender Separate Resistance figures based on Graphs 37 & 38

For the tender I multiplied the A & B coefficients (from the carriage adjusted curve by) 56/42 and used the same C. This gave A=692, B=31.2, C=0.733 for the Tender Adjusted Curve.

I subtracted the adjusted tender resistance values at various speeds from the Loco and Tender resistance at the same speeds. From these values I plotted a loco only curve and fitted an adjusted curve to fit this.
This gave A=6500, B= 31.2, C= 6.6 for The Loco Only Adjusted Curve.

I then ran an experimental resistance consist with the Individual Adjusted Davis figures, and next the Loco+Tender Adjusted Davis from Graph 37. They gave near enough identical resistance results for the same speeds.

As a matter of interest max speed with a Standard Davis Calculation (area 9m^2) from Fcalc2 gave a max speed of 65mph at 25% Cutoff and 100% Regulator, 586t trailing load.

Both types of experimental resistance consists gave 68mph at 25% Cutoff and 100% regulator, 586t trailing load.

So it looks like Davis may be a little conservative against real resistances but in either the case the train is nowhere near getting to 73mph.

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Re: Steam Physics

Postby systema on Tue Mar 14, 2017 3:16 pm

@Mick
I have your 71000 test files, but no test program so it seems I will sit this one out.

???

I received the debug programme from Peter in an email that was also sent to you and Darwin.

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Re: Steam Physics

Postby DarwinS on Tue Mar 14, 2017 7:32 pm

Small problem getting the OR debug working to record things, so just pottering around in the meantime.

One immediate observation with 71000 is with regard to boiler pressure. All the other boilers that I have so far tried in OR maintain steam pressure at maximum until you work them hard (or lose too much steam through the safety valves). This one is strange, boiler pressure starts to drop very early with no apparent reason, although it can be recovered later.
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Re: Steam Physics

Postby DarwinS on Tue Mar 14, 2017 9:11 pm

Following on from what Copperpen said about steam consumption falling... I was just watching this... a little above 60 mph consumption started to drop off. Then several times between 60 and 70 mph it started to increase again... then decrease again... past 70 it seems to only decrease, but I may try a run with a lighter train to see what happens at higher speeds.

Another thought for testing is do we want to employ an Australian fireman (or even one from USA)? Having SteamFiremanMaxPossibleFiringRate( 3500 ) would make it more likely that we can achieve the sustained high outputs we are looking for at the moment.
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Re: Steam Physics

Postby DarwinS on Wed Mar 15, 2017 6:52 am

Another observation on maximum power output. When you increase the cut off at higher speeds the steam usage and indicated horsepower increase. All well and good. When the indicated horsepower reaches the maximum defined by OR it stops increasing. However steam usage continues to increase... and increase. Surely maximum ihp and maximum cylinder steam usage should be the same, with steam usage not increasing any more when maximum power output is reached. There would certainly be a limit on steam usage - the amount of steam that can be exhausted through the blast pipe and chimney.

In MSTS there was an exhaust limit (although not an always an easy parameter to set). Is this needed in OR perhaps defaulting to 110% of maximum boiler steam production?

There were significant differences in the maximum possible power output between single and double chimney LMS Coronations. Similarly it has been mentioned here that 71000 has been improved by changes to draughting. There presumably needs to be a way to model this in OR. I am not sure about data for the examples so far mentioned, but BR did conduct a test with LMS Jubilees - and found that higher power output was possible with a double chimney. (However this was not widely applied as they found the firing rate needed to achieve the extra power was too high for human fireman or coal economy.) The results of this or a similar test may be among the testing data at York.
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Re: Steam Physics

Postby copperpen on Wed Mar 15, 2017 9:36 am

@Mick
First of all, I got todays email from Peter with the updated OR test file. Second, a query. Why do we have the 71000 set up with a GWR style notched reverser. Should be notchless like a steam or screw reverser.

I have also rediscovered a recorded run by 71000 from Euston to Rugby and on to Crewe with a load of 14 carriages, 453 tare and 485 gross. just under 84 minutes start to stop.
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Re: Steam Physics

Postby systema on Wed Mar 15, 2017 10:30 am

Why do we have the 71000 set up with a GWR style notched reverser. Should be notchless like a steam or screw reverser.


Its just me. I set my locos up this way as it is a lot easier to control the throttle and cut-off. Its also ideal when experiencing wheel slip. Quick taps on the #A key and the regulator is back to zero in a flash. Just like real drivers do it. I picked the idea up from watching various in cab videos. With a continuous control it takes too long to get to the desired settings. If you speed up the reaction setting its then too easy to overshoot the desired setting. HOWEVER, for CTN testing it is probably better to have continuous settings. My updated files will reflect this.

I have also rediscovered a recorded run by 71000 from Euston to Rugby and on to Crewe with a load of 14 carriages, 453 tare and 485 gross. just under 84 minutes start to stop.


Its about 85 miles to Rugby I think. Thats about a mile a minute which would include speed restrictions out of Euston and acceleration and deceleration times. Probably getting up to 80mph or more to meet that average speed. Of course the load is 200t less than the one we are using.

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Re: Steam Physics

Postby systema on Fri Mar 17, 2017 12:10 am

I have done test runs with 586t train Std 8P with Fcalc Davis and Plotted curve resistance. They basically give the same result, the latter giving a very small increase in top speed. Here are the graphs for interest. Maximum Speed achieved 70mph. Not sure what they mean other than the Drawbar TE and Coupler Force don't seem high enough. The resistances are close to real world results.



FCALC CURVES BASIC LOCO




Plotted Resistance from Graphs 37 & 38 BASIC LOCO

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Re: Steam Physics

Postby copperpen on Fri Mar 17, 2017 2:30 pm

My findings are broadly in line with just over 70 mph reached, and the drawbar/coupler forces seeming to be low.

While I am still not convinced that the figure for the steam used by the cylinders at any point in time is correct, I have been conduction a series of tests at different cut off rates and comparing the ITE for the shown OR cylinder steam rate with the 8P test Willans lines Graph 48. I am finding that depending on cut off, there are two things which do not fit the lines. The Willans lines start at 20mph and depending on the cut off, OR is probably giving more ITE than Willans shows up to a certain speed, at which point OR provides less ITE than Willans lines show. This crossover point is at a higher speed as cut off used is lowered. At 20% cut off the changeover point is around 20mph, but for 15% cut off this point is between 40 and 50 mph. The variation appears to be between 2000 and 3000lbf lower for OR than the Willans lines suggest. Difficult to say how much higher ITE is being provided at lower speeds as the Willans diagram does not provide any curves for them.
For instance with 35% cut off, using 33,643 lb/hr steam at 40mph, OR is providing 17,365lbf ITE. The Willans lines for that steam rate and speed show about 20,500lbf.
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Re: Steam Physics

Postby rickloader on Wed Apr 05, 2017 11:10 am

Hi everyone, some great work being done here! (although much is beyond me!). I think Darwin said there was no suitable route to replicate the controlled road tests between Wantage Rd and Stoke Gifford. Would it help if I built this route?
With TSRE5 it would not be a lot of work. No scenery ,just accurate grades and mileages.
There is a lot of test info on this site
http://www.traintesting.com/steam.htm

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Re: Steam Physics

Postby DarwinS on Wed Apr 05, 2017 6:17 pm

That is a nice offer Rick. :) The actual test we looked at was run Swindon to Reading West to Westbury. All of which is on Paddington to Penzance route but unfortunately the gradients on that section do not match real world closely enough to try to replicate the tests on that section of route. Certainly it would be interesting to see the results with 71000 which has been the subject of much fiddling for the past month.

However before we say yes, I think we had better see if there are any other tests we want to replicate there. It might not be worth the effort if we are only going to use it to test one locomotive. Having said that however, there are plenty of published logs of GWR locomotives running between Swindon and Paddington so it might be useful if we want to do performance tests on a GWR loco.

Wait and see what the other members of this discussion have to say, not least our CME steamer1960.

The only snag is that we would probably also want Kings Cross - Peterborough to do road tests for LNER locos! (Mid East UK does not have gradients out of London.)

There are however plausible routes for some LMS and some SR road tests.
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Re: Steam Physics

Postby rickloader on Wed Apr 05, 2017 7:43 pm

Thanks Darwin. Agreed it would not be worth building the route for just 1 loco, but there must be at least 6 tests on the website I gave, using this WR mainline. But possibly the main focus now is on other aspects of loco physics, so as you suggest I will wait and see what the others want.
I have my own test agenda on the 1 in 50 of Bincombe Bank between Weymouth and Dorchester. With MSTS physics the Bulleid light pacific stalls in ORTS. I`m hoping I can learn use the ORTS parameters to replicate the service load of 7 coaches, and Tangmere`s record run with 11 on.
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Re: Steam Physics

Postby DarwinS on Thu Apr 06, 2017 7:00 am

Hi Rick

We might help you with getting things correct for your Bullied Pacific, we are at the stage where we need to look at locos other than BR 71000 and if you have details of real life performance - logs from respected train timers or railway records such as dynamometer car recordings it might be a good idea to look at.

Just had a quick look at the test reports. Whereas 71000 was road tested Swindon-Reading-Westbury the Hall was tested in the other direction towards Badminton.

Thanks

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Re: Steam Physics

Postby rickloader on Thu Apr 06, 2017 7:24 pm

Thanks Darwin for the offer of help. I will climb in the roof to dig out my reference books. The "record" run I`m trying can be seen here. I hope you all find it inspiring! (Expert control of the slip near the tunnel)
https://www.youtube.com/watch?v=4BJcL7eM-as
I`ve been using Dave Robinson`s light pacific "Lapford" file id 27960 11 coaches 374 tons. (route is my in WIP New Forest route, but Dorset Coast should be the same)
Results Bincombe /Upwey bank 1 in 50
Real Life Tangmere 19mph at summit
MSTS Lapford 24 mph at summit
ORTS Stalled on the 1 in 50 (using MSTS physics)
I`m not trying to bash ORTS, but there is a need for non experts (like myself) to have guidance on setting up ORTS parameters. So I welcome the good work being done here.
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