Railworks America

The sound and physics on this locomotive leave something to be desired.

Has anybody ever attempted to correct either issue? This loco is included in the SD75Pack01.

In any case, I modified the dynamic brake maximum force to be 125, which seems higher than normal. However, the dynamics now work.

BTW, the max resistor current is stock at 1200.

Rob

I'm not sure on the physics of these. I guess I could google it but I can adjust the braking. That's about all I can do

JohnS wrote:I'm not sure on the physics of these. I guess I could google it but I can adjust the braking. That's about all I can do

That would be fine.

I did find something interesting. The sim doesn't read Horsepower. It only reads in KW. weird! Anyway, looking at the spec sheet for the engine it's 4300 horsepower @ 3200KW. The manual says that 1KW = 1.341Hp. So if want 4300Hp put 3200KW in this field not the horsepower of the engine.

A problem with the SD75M is that it accelerates and decelerates too fast. It seems like overpowered. It is quite difficult drive it in a yard below 15mph.
The brakes are not ok either, but are better than other old DLC.

jalsina wrote:A problem with the SD75M is that it accelerates and decelerates too fast. It seems like overpowered. It is quite difficult drive it in a yard below 15mph.
The brakes are not ok either, but are better than other old DLC.

I don't know how to adjust it, but I think it's the tractive effort vs speed and tractive effort vs throttle settings.
It' got the same physics as the SD70s.

Ericmopar wrote:I don't know how to adjust it, but I think it's the tractive effort vs speed and tractive effort vs throttle settings.
It' got the same physics as the SD70s.

We would need the curves. The SD70 are more modern. Maybe FanRailer has the info?
What is puzzling is the deceleration, so fast even when pulling a heavy train.

I have observed the CSX sd80mac and the ac6000wc (and maybe the Dash 8) and both have a sort of mechanical switching (maybe brakes release?) when they start running, so it takes a second or two before gains speed which makes them appear very realistic. This doesn't happen in the SD75.

ATSF had some SD75s rated for 4500hp from some other info I've found. I've made modifications to the power and speed curves on my loco based on FanRailer's methodology from a video he put out a while ago but haven't released any physics upgrades for diesels since I've been more focused on steamers.

Besides the Tractive Effort vs Speed there is also a Tractive effort vs Throttle curve.
I believe the issue with the deceleration is related to this second curve because when you cut throttle the speed falls pretty fast.

These two curves are easy to edit but i don´t have reliable data, other than trial and error.

The SD75 pack has the two models, the SD70M and the SD70I
The SD75I has no simulation folder. This means it must be using the same data than the SD70M, which may be right, but not sure. I read somewhere that the difference was the whisper cab for the I model.

jalsina wrote:Besides the Tractive Effort vs Speed there is also a Tractive effort vs Throttle curve.
I believe the issue with the deceleration is related to this second curve because when you cut throttle the speed falls pretty fast.

These two curves are easy to edit but i don´t have reliable data, other than trial and error.

The SD75 pack has the two models, the SD70M and the SD70I
The SD75I has no simulation folder. This means it must be using the same data than the SD70M, which may be right, but not sure. I read somewhere that the difference was the whisper cab for the I model.

It's using the same data as the SD75M, which is actually the same data used in the SD70Ace packs.

To calculate the curves you need to know the following:
1) The loco's maximum continuous tractive effort
2) How much horsepower the loco can still use after going through the alternator (DC locomotives usually still have somewhere in the vicinity of 80% of their horsepower left after transmission, AC locomotives are usually higher, around 90% or so).

from there plug it into this formula:

kN=(kW*3.6)/speed(km/h).

dtrainBNSF1 wrote:

jalsina wrote:Besides the Tractive Effort vs Speed there is also a Tractive effort vs Throttle curve.
I believe the issue with the deceleration is related to this second curve because when you cut throttle the speed falls pretty fast.

These two curves are easy to edit but i don´t have reliable data, other than trial and error.

The SD75 pack has the two models, the SD70M and the SD70I
The SD75I has no simulation folder. This means it must be using the same data than the SD70M, which may be right, but not sure. I read somewhere that the difference was the whisper cab for the I model.

It's using the same data as the SD75M, which is actually the same data used in the SD70Ace packs.

To calculate the curves you need to know the following:
1) The loco's maximum continuous tractive effort
2) How much horsepower the loco can still use after going through the alternator (DC locomotives usually still have somewhere in the vicinity of 80% of their horsepower left after transmission, AC locomotives are usually higher, around 90% or so).

from there plug it into this formula:

kN=(kW*3.6)/speed(km/h).

So for example here's some stuff I did on my copy of the Dash 9:
Max power: 4400hp (3281.079434961989kW)
Max power at rail: 3662.131247922655hp (2730.850801293343kW)
Max tractive effort: 142,000lbf(approx. 631kN)
Max continuous tractive effort@13mph: 105,640lbf(approx. 469.5kN)

My tevsspeed file has these values, calculated given the max power at rail figure and the formula I mentioned:
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<X d:type="sFloat32" d:alt_encoding="0000000000000000" d:precision="string">0.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000006066868B40" d:precision="string">631.647469</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="3">
<X d:type="sFloat32" d:alt_encoding="0000000000002140" d:precision="string">13.00000</X>
<Y d:type="sFloat32" d:alt_encoding="0000006066868B40" d:precision="string">469.910132</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="4">
<X d:type="sFloat32" d:alt_encoding="0000000000002E40" d:precision="string">15.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000F88340" d:precision="string">407.2553179608288</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="5">
<X d:type="sFloat32" d:alt_encoding="0000000000003640" d:precision="string">20.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000F07A40" d:precision="string">305.4418047913281</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="6">
<X d:type="sFloat32" d:alt_encoding="0000000000003E40" d:precision="string">25.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000007440" d:precision="string">244.3535956672532</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="7">
<X d:type="sFloat32" d:alt_encoding="0000000000C04240" d:precision="string">30.500000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000207040" d:precision="string">203.6280807417932</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="8">
<X d:type="sFloat32" d:alt_encoding="0000000000804640" d:precision="string">40.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000E06B40" d:precision="string">152.7209023956641</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="9">
<X d:type="sFloat32" d:alt_encoding="0000000000804A40" d:precision="string">50.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000E06740" d:precision="string">122.1767978336266</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="10">
<X d:type="sFloat32" d:alt_encoding="0000000000004E40" d:precision="string">60.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000206540" d:precision="string">101.8140403708966</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="11">
<X d:type="sFloat32" d:alt_encoding="0000000000005140" d:precision="string">65.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000206040" d:precision="string">93.98517099382433</Y>
<Name d:type="cDeltaString"></Name>
</cCSVItem>
<cCSVItem d:id="12">
<X d:type="sFloat32" d:alt_encoding="0000000000C05140" d:precision="string">70.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000C05D40" d:precision="string">87.27170612806453</Y>
<Name d:type="cDeltaString"></Name>
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<cCSVItem d:id="13">
<X d:type="sFloat32" d:alt_encoding="0000000000C05240" d:precision="string">73.000000</X>
<Y d:type="sFloat32" d:alt_encoding="0000000000C05940" d:precision="string">0.000000</Y>
<Name d:type="cDeltaString"></Name>
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The figures I used for the tevsthrottle file are from Al Krug's website: http://www.alkrug.vcn.com/rrfacts/dash9.htm

What also makes a difference in the engine's acceleration is the TimeToGetToMaxForce line and the MaxRpmChangePerSecond line as they determine how quickly the loco responds to the various changes to the throttle.

I have completed the brake mods and have sent my files to fanrailer. He will in time complete the phyics portion and release the mods together. I don't have any sounds for these even though they are powered by an EMD 710

JohnS wrote:I did find something interesting. The sim doesn't read Horsepower. It only reads in KW. weird! Anyway, looking at the spec sheet for the engine it's 4300 horsepower @ 3200KW. The manual says that 1KW = 1.341Hp. So if want 4300Hp put 3200KW in this field not the horsepower of the engine.

Just to clarify:

In the simulation.bin file, change 4300 to 3200KW or 3200 without KW? And do capital letters matter?

FHRob wrote:

JohnS wrote:I did find something interesting. The sim doesn't read Horsepower. It only reads in KW. weird! Anyway, looking at the spec sheet for the engine it's 4300 horsepower @ 3200KW. The manual says that 1KW = 1.341Hp. So if want 4300Hp put 3200KW in this field not the horsepower of the engine.

Just to clarify:

In the simulation.bin file, change 4300 to 3200KW or 3200 without KW? And do capital letters matter?

You don't need the capital letters. I believe that the max power line is in units of kilowatts in the bin file. Some are under the opinion that it's in units of horsepower in the bin file.

You guys are near to editing a few files and release a much needed mod for TS201x
FanRailer must know about those units if they are HP or kW.