There are a few physical considerations to put into a JMRI algorithm for 'momentum', and in my opinion some of them should be implemented with parameters that can be pushed during, not just at, runtime.
A typical DC throttle with momentum 'delay' and decay models some of the behavior that a 'scale heavy' train would have, both in rolling and with common sources of resistance like grades.
Turning it down models throttle reduction more than the action of explicit braking -- it could be thought of as backing off the throttle of a hybrid into 'regen'. Of course as Mel said you can 'learn' to turn the knob to mimick brake effort as well as 'reduced throttle' as the drive in most commercial locomotives is NOT full 'coasting' (and we've had numerous discussions about the perceived shortcomings of these in realistic operation!)
Meanwhile, both air and dynamic braking require modulation to be 'right' ... and brake application is nonlinear dependent on speed (see the various Decelostat/Decelakron devices for some discussion of why in a more relevant context than just physics) but this can be translated back out again in brake modeling to be more 'familiar' to automobile drivers ... much more fun than a 'prototype simulator' for many operators. It would also be possible to model the behavior either of normal pressure-maintaining one-pipe Westinghouse (under various climactic conditions, too) or graduated-release ECP.
The point is that one well-written physics simulator with specifiable settings and constants can 'do' any momentum scenario, as well as 'recognize' some common accident issues. It could then be packaged and compiled as an executable with any set of assumptions or scaling rolled in, if simplicity is desired, or if single-knob control with more 'realistic' appearance or momentum effect is wanted.
caldreamerI am currently writing the computer code for the protoype braking part fo the PTC system that I will be running on my new layout/
PTC doesn't run the train. PTC doesn't slow the train, it stops teh train. If PTC is stopping the train then the system thinks something is wrong or somebody has exceeded their authority.
There are other commercial systems (GE, Wabtec) that operate as a cruise control, but that is something additinal to PTC.
PTC is exclusively a safety overlay on top of the existing systems that keeps trains from exceeding the maximum speed or exceeding their authority. That's it. It is only effective on selected portions of each railroad.
Dave H. Painted side goes up. My website : wnbranch.com
The Iowa Scale Proto Throttle came up for discussion in a NCE forum. Some people are HUGE fans. One guy called it the most fun he has ever had.
It does require some tinkering to get the momentum and braking right. I'm not sure what they mean by that. It is said to be more user friendly with NCE than with some other systems. A user from Australia thought it was worth the 959 AUD he spent on the system. 300 of that was shipping. I guess the Brown Truck doesn't go to Australia, or if they do, it's not cheap.
Like Sheldon I am skeptical, but the hobby is big enough for everyone.
Henry
COB Potomac & Northern
Shenandoah Valley
caldreamer I am currently writing the computer code for the protoype braking part fo the PTC system that I will be running on my new layout/ It takes into account the train weight including engines, track grade and curvature, delay in braking while air propegates to all cars, etc. It is written in Java which is a computer language universal to all computer platforms. It will work with JMRI and all other programs that can execute Java code.
I am currently writing the computer code for the protoype braking part fo the PTC system that I will be running on my new layout/ It takes into account the train weight including engines, track grade and curvature, delay in braking while air propegates to all cars, etc. It is written in Java which is a computer language universal to all computer platforms. It will work with JMRI and all other programs that can execute Java code.
Will this be available for download online at some point? These kinds of programs interest me, in addition to all the other new ways to make operations more realistic.
I would love to have a program like this.
I'm beginning to realize that Windows 10 and sound decoders have a lot in common. There are so many things you have to change in order to get them to work the way you want.
I've got four MRC Tech II Locomotion 2500's on my layout. They've got momentum switches on them. With some of my older Atlas and Athearn locomotives, momentum won't give them a smooth start/stop, so I'll just use the regular throttle control. With my smooth running locomotives, and especially my Amtrak locomotives, I'll use the momentum to make smooth starts and stops at my Amtrak station. I also use the momentum when I want to make gradual speed changes or an "emergency" stop.
Granted, when using the normal throttle control, it's nice when you can get that perfectly smooth start or stop. I still remember when I was a member of the model railroad club back home, and I had a nice long freight of equipment I'd taken along for one of our open houses. One of the older members of the club wanted me to stop my train before going across a bridge because he wanted to check something. He was just around the corner of the layout from the train, and I'd already started slowing to make a nice smooth stop. He asked where it was, and I said "It's coming" with a big grin. Then he saw it creeping around the corner and coming to a perfectly smooth stop short of the grade crossing between him and the train. He turned to me with an ear-to-ear grin saying "Man, that was beautiful!"
Kevin
http://chatanuga.org/RailPage.html
http://chatanuga.org/WLMR.html
I think adding a little momentum to each locomotive does enhance realism when doing operations. The key is not to overdo.
Joe Staten Island West
I use momentum etting on my Tech 6 on my ISLs and I know when I get two cars from the switch to close the throttle and it will stop around 6 scale feet from the points. Just soon as The first car clears the points I shut the throttle off and ease to a "kiss" coupling.
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
Many of you who have only been around this hobby since DCC think this is a new question. Momentum throttles with braking effects go back way before DCC.
As several people have already pointed out, even on the largest club layouts every distance on a model railroad is compressed.
For this reason I have never been interested in:
Momentum, braking or Proto action throttles
Full blown multi step CTC
Trying to replicate actual prototype trackage arrangements
Compressed distances are also why I like the idea of only modeling one "place" and the trackage leading to and from it, rather than trying to model a beginning and a destination.
I run DC, and like davidmurray I use Crest/Aristo Craft Train Engineer wireless radio throttles. Speed control is done with push buttons, so even with zero momentum, there is a fixed rate of acceleration and deceleration. There is also an "emergency stop" button.
That is as close to prototypical stopping as I want get........even on my nearly eight scale mile long mainline.
Sheldon
I ran enough of "the big trains" wondering where or how I was going to "get it stopped", to want to fool with that on the little trains. I put a little CV4 "deceleration" on the engines, but not very much.
You might find it surprising, but it was the passenger trains (both Metro-North M2's and Amtrak) that could be more problematic with slowing and stopping than the freight trains, particularly in the snow or with leaves on the rails.
EnzoampsEinstein was right, it is all relative. We use fast clocks to speed up time, but slow motors to flip turnouts. Seems to be consistent we'd need turnouts to move super fast. Distances are short, Baltimore is two feet from Philadelphia, but we want a train to drift a mile trying to stop? Tried to stop in Balto, and the darn train took to Phila to stop.
I like that. Nicely put.
Well, on my layout, the day that I go down to the layout, turn on the lights, power up the system, a train sitting on the main, ready and waiting, and I see headlights from approaching pickups, a taxi, or an Uber car, the engineer and conductor get out, gather their duffle bags, and climb up in the cab, start up the train, clear things with the DS, and start rolling to a start, I'll keep using my throttle to start, and stop, as needed.
Heck, look at most locos on most layouts, even MR's, there's no crew! unless it's a P2K, or an early Bachmann "Plus", which came "crew equiped", there's no one in the cab.
Have fun with your trains.
I'll use my throttle.
Mike.
My You Tube
Einstein was right, it is all relative. We use fast clocks to speed up time, but slow motors to flip turnouts. Seems to be consistent we'd need turnouts to move super fast. Distances are short, Baltimore is two feet from Philadelphia, but we want a train to drift a mile trying to stop? Tried to stop in Balto, and the darn train took to Phila to stop.
Distances are compressed with most model layouts, even a big club has to compress distances. A scale mile might be the entirety of th emainline run for even a not super tiny home layout. SO you may have to adjust.
The othe thing is brakes - the train might coast for a mile, but what about braking? Many of the newer sound decoders support controlled braking as well. That's what's neat about the Proto Throttle for DCC, it has actual style controls, and you can actually work the brake. Sure beats trying to toggle an F key on and off on a regular throttle.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
When I got my Rapido Hudsons it was an eye-opener when I went to stop them. I remember seeing a video and how Jason and the gang were betting on where the engine would eventually stop. I am now tuned in to the stopping distance with those so hopefully there will be no whiplash lawsuits from my little riders.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
Given how relatively close our cities are compared to the real thing - even on a large layout - doing an accurate stop rate for a long train at high speeds might not work. One thing I have found interesting is using decoders which have a break function button, so if you just shut the power down to zero the train takes a long time to drift to a stop. You have to hit the brakes to get a quicker stop. To me that adds a lot of realism.
I use DC, with CREST train throttles. Using the heaviest momentum effect on that system the stopping distance is 60+ inches in HO.
I tried alone on my layout. It taught me to anticipate stops, but it helped that the system has an panic stop that only affects one throttle. Before friends came over for a ops session I reset to minimum momentum.
I would think on a large club layout, it could be cool. You'd have the track space, and probably a dispatcher controling everything.
On a small layout like mine, not so much. I slow mine down with the throttle, slow enough to fit my likes, and space.
Railfanning, and watching real trains, it kind of surprises me how quick they can start off from a stop, slow down, and stop.
The CN (the trains I watch) uses DPU's, and it must make a difference.
I recently got a loksound programmer, so much more freedom than the digitrax pr4. I was wondering if anyone has tried to program realistic stopping distances over a scale mile from mainline speeds or would that more likely result in my crashing into rollingstock and other trains? Or is it just unpleasant to deal with? We have a good sized club layout and the model in question is a large 4 truck turbine.