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Kennilworth
July 1st, 2013, 06:54 AM
Hi

There appears to be a problem with the built in GP60M and B units when used in mixed loco lash ups. Almost all such lash ups will only run at about 60% of maximum speed. After spending some time investigating this I've identified the problem as being due to the maxspeed tag in the engine spec.

The GP60M engine spec has its maxspeed tag set to 49.1744 while in most other SP and ATSF locos built in the tag is set to 31.3. The only loco that I've been able to use at full speed with the GP60s is the built in ATSF B40-8W which uses the same GP60 engine spec.

When I edited the GP60 engine spec maxspeed tag to 31.3 to bring it in line with the other locos that I use, the lash ups were able to run at full speed.

The problem with editing the engine spec yourself is that any sessions that use them can't be used by other people unless they know how to make the same edit so would it be possible to release a modified GP60 engine spec to enable these locos to be used in mixed lash ups in sessions?

Thank you for any consideration that you may give this.

Regards

Brian

nicky9499
July 1st, 2013, 09:12 AM
I've been facing this issue as well. Would love to hear some views regarding editing the enginespec and uploading/hosting it under our own kuids.

norfolksouthern37
July 1st, 2013, 09:45 AM
is this under AI control only?

are you saying the GP60Ms can only run 60% of their max speed, or 60% of the lowest max speed in the consist? define maximum speed.

GP60Ms are geared differently to pull fast intermodal trains. the fact that there is a difference in max speeds is no accident. if you can tell me exactly what is going on here and we determine an edit needs to be made i can make the changes and add to the DLS.

Kennilworth
July 1st, 2013, 11:30 AM
Hi

This is happening running with AI trains with different locos on the head end but including at least one GP60. I ran tests on the section of the Mojave route between Barstow portal and Mojave yard where the max speed limit is 70 mph. With a consist consisting of three GP60Ms or 2xGP60M plus one ATSF B40-8W the consist ran at maximum line speed of 70 mph. The ATSF B40-8W uses the GP60M engine spec.

However with two GP60s plus one C30-7 the consist maxes out at 45mph and cannot be persuaded to go any faster. The same thing applies if I use other locos (SD45 and SD40-2) with the GP60s when the consist maxes out between 45 and 50 mph depending on the other loco.

Using the C30-7 consist as an example, if you multiply the maximum line speed (70 mph) by the C30-7 maxspeed of 31.3 and divide by the GP60 maxspeed of 49.1744 the answer is 44.56 which rounds up to 45 mph. It would seem that the physics for AI trains works out the consists top speed in this way when multiple locos of different types are used.

As I mostly model UK practice I'm afraid that I don't know very much about the differences or history of US locos but I do enjoy running on US routes for a change and have found this issue very frustrating when trying to build sessions. I suppose the easy answer is not to use the GP60s with other locos but I like the look of them and assume that in real life they would run with other different locos.

Regards

Brian

norfolksouthern37
July 1st, 2013, 01:28 PM
Using the C30-7 consist as an example, if you multiply the maximum line speed (70 mph) by the C30-7 maxspeed of 31.3 and divide by the GP60 maxspeed of 49.1744 the answer is 44.56 which rounds up to 45 mph. It would seem that the physics for AI trains works out the consists top speed in this way when multiple locos of different types are used.

it does not quite work that way.

49.1744 = 110 mph - this is a little overkill for the 60s (90 mph was the top iirc) but i wanted to be sure they could reach speed with no problem.
31.3 = 70mph

the spec values are supposed to be in meters per second.

why this causes a 45mph top speed i do not know, but i am interested in finding out if you don't mind doing the testing.

Kennilworth
July 1st, 2013, 02:45 PM
Hi again

Yes I'll carry out more testing for you. Is there anything in particular that you want me to try? If not, I'll try altering the maxspeed figure for the GP60s in smaller stages and see if the ratio holds up and then try the same thing using different locos.

Regards

Brian

Kennilworth
July 2nd, 2013, 05:38 PM
Hi again

I've spent quite some time today experimenting with different locos and also changing the maxspeed figures. In all cases they behaved in accordance with the formula "lowest maxspeed / highest maxspeed * line speed limit". I tried various combinations of locos, speed limits and maxspeed figures but the formula held true in all cases. Obviously this is hard coded in the core code somewhere.

This seems to me to be illogical as even if the smallest maxspeed figure is higher or equal to the speedlimit the consist still runs at a percentage of the line speed instead of full line speed. This is probably not noticeable if all locos have a similar maxspeed figure but in the case of the GP60s the maxspeed figure is so much higher than other locos that it magnifies the effect.

It would seem that we need to be careful when mixing locos and avoid using locos with particularly high maxspeed figures with any that have low maxspeed figures.

Regards

Brian

norfolksouthern37
July 2nd, 2013, 11:37 PM
I've spent quite some time today experimenting with different locos and also changing the maxspeed figures. In all cases they behaved in accordance with the formula "lowest maxspeed / highest maxspeed * line speed limit". I tried various combinations of locos, speed limits and maxspeed figures but the formula held true in all cases. Obviously this is hard coded in the core code somewhere.


okay so using that formula in your first example:

first loco maxspeed = 31.3 or 70mph
second loco maxspeed = 49.1744 or 110mph
track speedlimit = 31.3 or 70 mph

31.3 / 49.1744 * 31.3 = 19.92276469 or 44.566 mph

45 mph is that max speed this train will go on track set for 70mph - it seems someone from programming should step in here and let us know whats going on. that does not seem like the right way to implement that.

jordon412
July 6th, 2013, 08:37 PM
How do I convert the prototype's max speed to the maxspeed in the config file? This would be very helpful for the locomotives I make to be more realistic.

Kennilworth
July 7th, 2013, 01:37 AM
Hi Jordan412

Just google "MPH to Meters per second" and you will find a number of conversion programs, any of which will give you the answer.

Regards

Brian

jordon412
July 7th, 2013, 12:27 PM
Hi Jordan412

Just google "MPH to Meters per second" . . .


I didn't know it was that simple. I'll try to remember that.