Higher gearing for F7's

Discussion of rolling-stock creation & re-painting.

Higher gearing for F7's

Unread postby rickintucson » Sat Feb 25, 2012 9:48 pm

Hi Folks,

I would like to know if it is possible to "regear" the F7s for 110 mph or thereabouts. The SuperChief (with F's) would maintain 100+ mph speeds on the "racetrack", western Kansas and eastern Colorado for a bunch of miles. Even Amtrak (maybe not now-but several years ago) would be above 95 over the same mileage.

I can't seem to get the F7s above 94.2 except on a down grade.

Let me know how it might be possible to do this.

Thanks!

Rick

P.S. Or maybe E9's..........just wishin.........
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Re: Higher gearing for F7's

Unread postby NDORFN » Sat Feb 25, 2012 10:23 pm

That's actually a really good idea. I'm surprised no one's thought of it.
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Re: Higher gearing for F7's

Unread postby Kali » Sun Feb 26, 2012 1:34 am

First off set the Maxspeed setting in the simulation blueprint to something it will never reach ( the speedo stops at 500mph, use that ). Now you have to balance the tractive effort - this is only possible to do properly for D-E if you script it, so we'll just do an improper one.

Open the TractiveEffortVsSpeed graph, which is actually just a list of numbers. One set are speed, the other set is the maximum possible tractive effort at that speed. For higher gearing, what you need to do is decide what proportion higher your gearing is than the standard gearing ( I'm going to use 25% here ). Now, you have 25% less TE at a given speed, so you need to divide each TE entry by 1.25... but that's available at 25% higher speeds, so you can multiply the speed entries by 1.25.

If it gets to 110mph and won't stop accelerating then you don't have enough drag, so go into the engine blueprint and start raising the drag coefficient.

I'm pretty sleepy so there might be a glaring flaw in the maths there, but that's the idea anyway.
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Re: Higher gearing for F7's

Unread postby rickintucson » Sun Feb 26, 2012 9:53 am

Thanks so much Kali, I have a few questions for you if you would be so kind.

Kali wrote:First off set the Maxspeed setting in the simulation blueprint to something it will never reach ( the speedo stops at 500mph, use that ). Now you have to balance the tractive effort - this is only possible to do properly for D-E if you script it, so we'll just do an improper one.


If I were to do this:
1. Where will this be?
2. Will this change all engines I use? i.e., would a GP9 also be affected?
3. What language, xml?

Kali wrote:Open the TractiveEffortVsSpeed graph, which is actually just a list of numbers. One set are speed, the other set is the maximum possible tractive effort at that speed. For higher gearing, what you need to do is decide what proportion higher your gearing is than the standard gearing ( I'm going to use 25% here ). Now, you have 25% less TE at a given speed, so you need to divide each TE entry by 1.25... but that's available at 25% higher speeds, so you can multiply the speed entries by 1.25.


1. Where is the TractiveEffortVsSpeed graph located?
2. What language, xml?

Sorry to be such a neophyte, but thanks for your help!!

Rick
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Re: Higher gearing for F7's

Unread postby Kali » Sun Feb 26, 2012 1:08 pm

rickintucson wrote:Thanks so much Kali, I have a few questions for you if you would be so kind.
If I were to do this:
1. Where will this be?
2. Will this change all engines I use? i.e., would a GP9 also be affected?
3. What language, xml?


I'm not in a position to check properly atm, but:

1. Somewhere in the F7 folder tree wll be one called "Simulation". Inside that will be something probably called F7 Engine Simulation.bin, or something along those line - it should be reasonably obvious. If it isn't, or you have more than one bin file in there, you'll have to check one of the engine bin files for one of the repaints you want to edit.
2. It will affect all the F7s that use that blueprint, which is probably all of them.
3. Practically everything in Railworks is xml

rickintucson wrote: 1. Where is the TractiveEffortVsSpeed graph located?
2. What language, xml?


1. See #1 above
2. See #3
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Re: Higher gearing for F7's

Unread postby rickintucson » Sun Feb 26, 2012 3:17 pm

Thanks for all the help Kali!!!


Rick
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Re: Higher gearing for F7's

Unread postby rickintucson » Mon Feb 27, 2012 11:26 pm

Hi Kali,

I have tried the following: I set the MAXSPEED for 500,

Adjusted the speeds higher by 25% at each TE, then tested-not much change.
Adjusted the TE as much as 200% at the stock speeds, then tested-still not much change.

After all that I still max out at about the same speed of 95.

The only way I get any more than a .5 miles per hour difference was if I change the "maxpower" setting to 3000 which is double the 1500 it comes with, but I only get an additional 3.3 mph with this.

I haven't been able to find the drag settings, so this may be the issue, speed increases seem to slow dramatically once crossing 90 mph no matter what, so I am left to conclude there is another setting in some dcsv file somewhere that I haven't found???

If you or anyone else has any time to respond I would be grateful!!

Thanks,
Rick
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Re: Higher gearing for F7's

Unread postby rickintucson » Wed May 30, 2012 11:17 am

Hi folks,

I forgot to respond to this thread with my final results, and decided to do so since there is new question about engine speed in a new thread, and this may help.

While the tractive effort and drag issues mentioned in this thread may be a factor, in my case with the F7's (and now the E8's) it didn't make a discernible difference, so I left that alone.

Here is exactly what I ultimately did to get prototypical speeds out of the F7's (for passenger use-Santa Fe ran them at up to 108 or so):

1. As Kali suggested, I found the "maxspeed" line in the engine "SIMULATION" file. Each engine has one.
2. I set up a test track, 30 miles long and flat.
3. I set up a test train, 3 lightweight passenger cars per engine, in my case it was five F7's with 15 cars.
4. My desired loaded speed was 108 mph, and then I experimented with a "maxspeed" setting that produced 108 with that load, within a minimum of 10 miles and a maximum of 15 miles of running.
5. My "maxspeed" setting was-as I recall-14% higher than the maximum speed I wanted, or 125 mph. Easy way to figure it out was to divide my desired speed by .86.
6. I verified this procedure again last weekend, as I did the same with Britkits new E8/9 units. E8/9's were 2000 to 2200 hp, so I wanted to haul 4 lightweight pass cars per engine at 108mph, also producing a "maxspeed" of 125. Dick's engines come with a "maxspeed" setting of 92, producing a loaded speed of approx 87 or so, or about 19 mph slower than Union Pacific ran them in the 1950's and 60's.

I may experiment with the tractive effort and drag coefficient at some time in the future if I get bored, but since the above settings produce the results I wanted, I'm happy for now.

If you do this, please back up your files so you can revert to original if this messes you up.

Hope this helps.

Rick
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Re: Higher gearing for F7's

Unread postby Kali » Wed May 30, 2012 11:49 am

Maxspeed is a hard cap on speed - it starts having an effect 10mph before the speed itself ( say the docs! not convinced it doesn't start earlier, hence I just make it irrelevant ), so no matter what you do to TE it's going to stop you going any faster. That might be what happened earlier. Messing with that will get you a prototypical top speed, but the journey there might be somewhat less than realistic, let's say - if that doesn't matter much to you, then you're golden. I think it also stops you going any faster even if you're going down a steep hill, which feels wierd.

The other engine-related thing that will effect top speed is the TEvsSpeed graph; if that nosedives at 95mph, then no matter what you do elsewhere you won't get over ( or probably to, even ) 95mph. Set MaxPower to whatever you like, at 95mph the graph will just cut your power off.

Here's the chain of events to determine how much TE to put out ( for the diesel-electric model ):
  • Calculate using MaxPower, the setting of the Regulator control and the train speed, the value of (Power/Speed)*Regulator. That will get you a TE figure.
  • Get the value from TEvsRegulator for the current Regulator control setting
  • Get the value from TEvsSpeed for the current train speed.
  • Pick the lowest of all three, and use that - this might mean that most of the throttle control range becomes useless because changing it doesn't do anything; the default HST is a good example. This might also mean that increasing the MaxPower figure doesn't do anything either except make the throttle even more useless. Minimising these effects without making the engine go nuts is most of the art of performance tuning...

Countering that is drag; rolling resistance is constant when you're on flat track, aerodynamic drag goes up with the square of the speed. If there's some particularily draggy stock ( and some of it is ludicrously draggy ) then you're going to need a lot of power to go any faster pulling it. More power also means you accelerate faster and don't slow down on hills so much, so you have to think whether you really want to add power rather than removing some drag.
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Re: Higher gearing for F7's

Unread postby rickintucson » Wed May 30, 2012 11:58 am

Hi Kali,

Thanks again.

I agree with you on your analysis, however, when I made those changes, it resulted in minor improvements. My concern was were those improvements worth the price-and maybe they are to a purist, but the maxspeed setting got me 95% of what I wanted.

True, it could be tweaked, but using the theory of diminishing returns, it was my thought I could spend more time on the scenery!

Since I only made what I consider to be a minor (<20%) change to speed, I don't think those other issues came in to play. To your point however, making a more substantive change could probably cause more problems requiring better physics adjustments as you suggested .....

In all, the acceleration is brisk in the lower speeds, and by the time you reach 92 the increases are definitely slower, producing a speed curve that is acceptable to me.

Maybe sometime I will graph it out so I can improve upon it.

Thanks again,
Rick
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Re: Higher gearing for F7's

Unread postby Kali » Wed May 30, 2012 12:05 pm

"Happy with it" is always good enough :)
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