HST notch position realism

[dgm486]

Hi all,
As a rail enthusiast and newcomer to TS2015 I have to say it is actually much better than I feared reading the many bad reviews. It seems to do many things well, but the one thing that really irritates is the unrealistic power settings at speed. A HST should need notch 2 at 100mph and 3 or 4 to hold 125, but in TS2015 it is 1 and 2. Is there anybody that has worked out how to fix this by editing the BIn file or something similar?

Many thanks and forgive me that perhaps his belongs on the Physics section.

[gptech]

Hi,
these might help, though as I've not installed them I can't say for certain

HST Update of exhaust/brake/ATP/rear sound [216422 bytes] - hst_drb_a1z.zip File ID: 23719 Date: 12 Apr 2010 - 1894 Downloads

Improved HST Driving Physics [44693 bytes] - HST_update.zip File ID: 19974 Date: 26 Oct 2008 - 1202 Downloads

Don't let the fact that they were written for older versions of the game put you off, 99% 0f older stuff still works in TS2015. Usual rules apply----mess about with a copy of an HST until you know it works OK, and take a backup first!!

[ttjph]

Ah, I hadn't spotted that Improved Physics before hacking it myself a little while ago!

The basic problem (with several 'original Kuju' locos I believe) is that the TractiveEffortVsSpeed curve falls below the (calculated) constant-power curve at higher speeds - basically it limits the power at high speeds to less than half the installed power. Therefore, you need to reduce to notch 2 or below (i.e. below half power) before the throttle has any effect.

Setting TEvsS to a large value at all speeds makes it drive on the throttle as it should, and incidentally will also make it quicker at high speeds due to more power being available (you might like to leave a zero value in at a very high speed, say 135 or 140 mph, to simulate the transmission 'unloading').

[ttjph]

Just viewed those uploads and:

1. The "exhaust/brake/ATP/rear sound" patch looks to include all the contents of the "physics" one.

2. Neither appears to address the issue discussed here. If you like I'll dig out the affected file(s) and send them to you (you may need to PM me an email address); or if I get a few minutes I'll upload to UKTS. Or you can have a go at editing the file yourself.

[ttjph]

OK, looks like it's just the one file:
...\Assets\Kuju\RailSimulator\RailVehicles\Diesel\HST\Default\Simulation\TractiveEffortVsSpeed.dcsv
(although depending on how many versions of the HST you have, you may need to copy it into several other locations)
and mine now looks like this (basically setting the max tractive effort to 80 kN at every speed except 140 mph):

Code: Select all

<?xml version="1.0" encoding="utf-8"?>
<cCSVArray xmlns:d="http://www.kuju.com/TnT/2003/Delta" d:version="1.0" d:id="1632656">
	<CSVItem>
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			<X d:type="sFloat32" d:alt_encoding="0000000000000000" d:precision="string">0.000000</X>
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			<Name d:type="cDeltaString"></Name>
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			<Name d:type="cDeltaString"></Name>
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			<Name d:type="cDeltaString"></Name>
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			<Name d:type="cDeltaString"></Name>
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			<Y d:type="sFloat32" d:alt_encoding="0000000000003240" d:precision="string">14.000000</Y>
			<Name d:type="cDeltaString"></Name>
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	</CSVItem>
</cCSVArray>

You're supposed to be able to edit these with Excel, IIRC, but I think I just used Notepad. I just edit the decimal values at the ends of the lines, and hope that the hex values sort themselves out... it seems to work!

Always take a copy of the original file before editing!

[dgm486]

Hi ttjph,
Thank you for the responses. Really appreciate it. I understand what you suggest, which is eliminating the decreasing TE with speed. But, I don't think this will solve the notch position problem. It will mean that the throttle notch now correctly makes a difference at speed, so it is half of the puzzle thank you. But with more power available at 125mph the train will continue to accelerate unless it is back in Notch 2. Seems the Kuju model incorrectly uses a straight fall off in TE vs. speed to compensate for too low a value in wind resistance. Or, the fall off in TE vs. speed should actually be pro-rata with Notch position. Don't suppose you might know where I would go looking to correct one of these things? In the Engine.bin file presumably?

Thanks again.

[ttjph]

With TEvsS out of the way, it models a constant-power tractive effort curve fairly well, so falls off as 1/speed.

Another thing you could check is whether the power is set to 2250, which is the headline engine horsepower - if so, it should probably be reduced to around 1800-1900 (80-85% efficiency for a fairly old DC electric system), which would help. This would be in the engine.bin (possibly Class43.bin) file.

After that, if it's truly prototypical to need Notch 3 or 4 to maintain 125mph on the level, then you could try adjusting the drag values. There's definitely a rolling resistance term (which is multiplied by the vehicle weight) and presumably there's also an aero drag term. I don't know how the sim handles coaches - apparently real train aero drag is heavily influenced by skin friction (so length of train) as well as the gaps between vehicles (part-filled container trains are bad, mmmkay!) but it's probably just a single number.

Good luck, and let us know how you get on!

[AndyUK]

Both drag and rolling friction are modelled for each type of vehicle and as correctly surmised they are in the .bin files where DragCoefficient and RollingFrictionCoefficient are specified. So in the case of the HST the files concerned are, using the one in the Kuju asset folder as an example - mk3tgs_ic.bin, mk3tso_ic.bin, mk3trfb_ic.bin, mk3tfo_ic.bin and class43_ic.bin.

The power is specified in the simulation file, in this case HST Engine Simulation.bin. In the past when playing with loco performance adjustments I've used the quoted max power at rail (in HP) for the MaxPower figure. I suppose an allowance should also be made for ETH but i've never bothered with that.

Andy L

[dgm486]

Hi,

Thank you for the advice and pointers. I worry I know only enough to be dangerous, but this gives me enough to have a play. I'll let you know how I get on.

Thanks again.

[ttjph]

If the drag coefficient is truly that, what area does it use? Or is it actually a CdA value?

[ttjph]

Can confirm that the default has 2250 hp at the rail. I've now edited all mine down to 1770 (Wikipedia value - I was close though!) but haven't had a run since to see where it balances at 125.

[AndyUK]

If the drag coefficient is truly that, what area does it use? Or is it actually a CdA value?

From the RailWorks wiki (http://railworkswiki.com/tiki-index.php): "This figure (the drag coefficient) is related to the Air Resistance of the Vehicle. This value is scaled by the square of the speed and so has most impact at higher speeds. This term combines the cross-sectional area and the traditionally quoted drag coefficient which itself is dependent on the profile the vehicle presents to the wind."

Some more from the wiki shows how Kuju arrived at the figure they used for drag coefficient: http://railworkswiki.com/tiki-index.php ... n+Elements

Andy L