True slow scale speeds - no jerking

[Noel]

I posted this before somewhere a few years ago, but this is what I mean by smooth ultra slow speed running under DCC when the chips are optimised. IMHO, scale models should be able to start smoothly and not at scale speeds of 25mph. Some lovely scale models are let down by toy standard mechanicals on their chassis.

 

Edited September 8, 2016 by Noel

[Warbonnet]

True Noel, the last thing you want your loco doing is jerking off to a start.

[WRENNEIRE]

Fran

And you a moderator and all....

[Weshty]

How vewy vewy wibald.

[Noel]

fran

and you a moderator and all....

 

roflmao

 

PS: The Bachmann/MM baby GMs are the best geared and smoothest running chassis I have ever seen compared to other Bachmann, Hornby and Athern.

Edited September 10, 2016 by Noel

[Garfield]

There's a misconception that locos crawl along at that speed in reality. They generally don't, unless they're fitted with slow speed control (used with auto-discharging hoppers, etc.). An 071 and a rake of Mk2s would have accelerated quite a bit by the time the last coaches reached the end of the platform...

Edited September 10, 2016 by Garfield

[Junctionmad]

There's a misconception that locos crawl along at that speed in reality. They generally don't, unless they're fitted with slow speed control (used with auto-discharging hoppers, etc.). An 071 and a rake of Mk2s would have accelerated quite a bit by the time the last coaches reached the end of the platform...

 

indeed , and any video of loose shunting, will show you these boys moved the stock and the locos around quite sharpish. They had a job to do after all, certainly with the exception of the last few steps in buffering up , locos moved around at well above creep speeds

[Noel]

indeed , and any video of loose shunting, will show you these boys moved the stock and the locos around quite sharpish. They had a job to do after all, certainly with the exception of the last few steps in buffering up , locos moved around at well above creep speeds

 

Careful now! We've already had 'jerking' by a mod, and now 'creep' by somebody who may be insane about junctions.

 

 

Patrick is right and the beginning of clip below illustrates his point about high powered 071 pulling a rake out of Heuston, but it starts off at walking pace not 25mph like many models.

 

 

I know locos didn't crawl continuously like my 141 v 071 clip, but at initial start the older locos on medium to heavy trains were very slow pulling off. Too many models are operated going from zero to 25mph rather than prototypical acceleration curve. Watch clips of heavy beat trains pulled by a pair of baby GMs, and it takes ages for them to get to even 20mph.

[Mayner]

Rate of acceleration depends a lot on the weight of the train, the nature of the service and power of the loco.

 

Auckland Transport's push-pull sets reminded me of the Baby Metrovicks on pre-DART suburban services with slightly better rolling stock.

 

[Sulzer201]

Great vid John, interesting push/pull service as alternative to purely dmu trains. Am I right in thinking that those carriages are refurbished ex BR Mk IIs?

Regards, Tommy

[Garfield]

These old girls had a lively rate of acceleration with a seven-coach rake (speed limited by the limit on the curve heading west out of Mullingar...):

 

[Noel]

These old girls had a lively rate of acceleration with a seven-coach rake (speed limited by the limit on the curve heading west out of Mullingar...):

 

 

Loco got to 3mph in its own length, and the train was doing 13mph when the last coach went under the bridge.

[Noel]

PS: On this video of the 071 and six mk3s, from start the loco got to 4mhp in its own length and entire train had only got to 20mph by the time the last coach passed the carriage shop. Acceleration was not as fast in the prototypical world as the eye might perceive probably due scale, vision, etc. Now I could have made a total botch of the basic arithmetic but I thinks its within a 10% error margin.

 

[Junctionmad]

I think , speed like mass is one of the things that doesn't scale well. Ok most layouts , track is compressed length wise and so prototypical starts would look odd as the loco would cover the whole layout accelerating. So I think there's a happy compromise. The issue for me is to contain jerky movement as this distroys the illusion of mass. I think many modellers are forced to accelerate the model to overcome issues with poor track or pickups.

 

A consistent acceleration to me is preferable over necessarily crawl speed ability. ( which in reality is a simple function of gearing )

[Noel]

I think , speed like mass is one of the things that doesn't scale well. Ok most layouts , track is compressed length wise and so prototypical starts would look odd as the loco would cover the whole layout accelerating. So I think there's a happy compromise. The issue for me is to contain jerky movement as this distroys the illusion of mass. I think many modellers are forced to accelerate the model to overcome issues with poor track or pickups.

 

A consistent acceleration to me is preferable over necessarily crawl speed ability. ( which in reality is a simple function of gearing )

 

Agree smooth constant acceleration and deceleration which thankfully most high quality RTR chassis nowadays can provide (e.g. all the MMs). Don't agree entirely it doesn't scale well to operate trains at scale speeds, acceleration and braking. There is nothing worse than seeing a superb exhibition layout with fine scale models driven in a totally unrealistic manner with trains stopping at speeds where G forces would knock all the passengers out of their seats and off their feet. Fine for a 1970 Triang-Hornby toy but not a fine scale model.

[Junctionmad]

Agree smooth constant acceleration and deceleration which thankfully most high quality RTR chassis nowadays can provide (e.g. all the MMs). Don't agree entirely it doesn't scale well to operate trains at scale speeds, acceleration and braking. There is nothing worse than seeing a superb exhibition layout with fine scale models driven in a totally unrealistic manner with trains stopping at speeds where G forces would knock all the passengers out of their seats and off their feet. Fine for a 1970 Triang-Hornby toy but not a fine scale model.

 

Yes , but, the neccessary length compression of layouts means that deacceleration and acceleration occurs over a much shorter then scale distance and hence occurs over a far shorter time interval.

[Noel]

Yes , but, the neccessary length compression of layouts means that deacceleration and acceleration occurs over a much shorter then scale distance and hence occurs over a far shorter time interval.

 

Hmm, most private layouts have a 'roundie roundie' element so there is plenty of scale distance to accelerate in a gentlemanly and scale like manner that would not spill tea in the dinning carriage. Appreciate this is not possible on some end to end exhibition layouts, but they were not designed to display trains at cruising speeds anyway so its not an issue.

 

On our layout the largest mainline loop is the equivalent of 0.8 scale miles, so plenty of distance to accelerate before doing a full 360. Your Claremorris may not be too far off those distances either. On a long heavy freight train I often allow two laps of the layout to simulate braking and gradually coming to a halt. Modelling inertia is a key element for me in operating toy trains. I have to use my 'imagination' that the second time the train passes a through station that it is in fact a different station.

[Garfield]

Loco got to 3mph in its own length, and the train was doing 13mph when the last coach went under the bridge.

 

Not a bad rate of acceleration at all.

 

Having studied the video, the train was already travelling at 0.7mph after one second. In your video of the models at the top of the thread, the 071 is travelling at a steady scale 0.29mph.

 

There should be a law against doing maths on a Sunday...

Edited September 11, 2016 by Garfield

[Noel]

. . .

There should be a law against doing maths on a Sunday...

 

Agree

 

I guess this clip is a better example of an attempt at scale speeds

 

Clip:

[Glenderg]

What's being said here is that your so-called "scale speeds" are too slow.

 

Real speeds are almost 2.5 times faster in real life than your model speeds, so you're seeking perfection for a thing that does not happen.

[Noel]

What's being said here is that your so-called "scale speeds" are too slow.

 

Hi Richie, YES in the 141 v 071 clip which is un-prototypical.

 

But the clip shows what a good chassis can do, and therefore how a good chassis can do scale like acceleration and deceleration (not in that clip). I've timed models with speed gates to find out the correct scale speeds and acceleration distances. The MMs are near perfect, and yes if you leave a model at speed step 1 it will go at a constant low speed that is lower than attainable in real life. Noel

 

Real speeds are almost 2.5 times faster in real life than your model speeds, so you're seeking perfection for a thing that does not happen.

 

2.5 times?

 

In a week or two when I get some time will post a clip showing scale acceleration and deceleration speeds and distances using a 141 and an 071.

[Sulzer201]

What's being said here is that your so-called "scale speeds" are too slow.

 

Real speeds are almost 2.5 times faster in real life than your model speeds, so you're seeking perfection for a thing that does not happen.

 

Have to agree...this 'rivet counting' approach to scale speed perfection can be taken too far and at the end of the day we have to keep some perspective.

[Noel]

Have to agree...this 'rivet counting' approach to scale speed perfection can be taken too far and at the end of the day we have to keep some perspective.

 

Me too believe it or not. Too much time on my hands with bad dose of flu these past 3 days!!! Enough

[Mayner]

 

My take on slow speed the 2-8-0 is DCC the 2-8-2 on board battery RCS RC the apparent pause by the 2-8-0 at 14 sec seems to be something to do with the optics of the camera.

 

DCC radio control is not 100% reliable with the range involved and the signal bouncing off obstacles so CV3 acceleration rate is set to 3 CV4 deceleration rate is set to zero. The 2-8-2 is running on pure DC with an electronic speed controller with acceleration and inertia at the default settings.

 

My locos need to be responsive to the controller stop on command to avoid cornfield meets and damage to stock while switching.

 

There is a lot more inertia with large scale stock and need to be careful starting a train to avoid splitting facing points and avoid the Conductor and brakemen spilling their coffee or falling from the roof boards while tying down those handbrake wheels.

 

I follow the same principal with my small scale Irish narrow gauge locos are geared at 80:1 with a can motor and single flywheel motor and run on dc to allow the motor to develop maximum torque when starting and allow reliable low speed running at full throttle.

[Junctionmad]

Hmm, most private layouts have a 'roundie roundie' element so there is plenty of scale distance to accelerate in a gentlemanly and scale like manner that would not spill tea in the dinning carriage. Appreciate this is not possible on some end to end exhibition layouts, but they were not designed to display trains at cruising speeds anyway so its not an issue.

 

On our layout the largest mainline loop is the equivalent of 0.8 scale miles, so plenty of distance to accelerate before doing a full 360. Your Claremorris may not be too far off those distances either. On a long heavy freight train I often allow two laps of the layout to simulate braking and gradually coming to a halt. Modelling inertia is a key element for me in operating toy trains. I have to use my 'imagination' that the second time the train passes a through station that it is in fact a different station.

 

I suppose I was merely countering your comment on exhibition layouts , which are sometimes out and back , or scenic break type layouts. In this case repeated circling of the layout to achieve near scal deacceleration would look odd and wrong.

 

Again Take a model railway that is signalled , berth and clearance distances will have been compromised significantly but trains still need to decelerate and stop within the model signalling distances allowed. That's means far greater deceleration and acceleration then the prototype. In fact prototypical rates would look distinctly wrong.

 

Nothing in this takes away from a good model chassis, but model crawl speeds are more a function of gearing and pickups. While the MM 141 is impressive, when I see it matched in a G class two axle diesel , I'll be seriously impressed. ( and across a dead frog peco to boot !!j

Edited September 12, 2016 by Junctionmad

[Junctionmad]

Hmm, most private layouts have a 'roundie roundie' element so there is plenty of scale distance to accelerate in a gentlemanly and scale like manner that would not spill tea in the dinning carriage. Appreciate this is not possible on some end to end exhibition layouts, but they were not designed to display trains at cruising speeds anyway so its not an issue.

 

On our layout the largest mainline loop is the equivalent of 0.8 scale miles, so plenty of distance to accelerate before doing a full 360. Your Claremorris may not be too far off those distances either. On a long heavy freight train I often allow two laps of the layout to simulate braking and gradually coming to a halt. Modelling inertia is a key element for me in operating toy trains. I have to use my 'imagination' that the second time the train passes a through station that it is in fact a different station.

 

I suppose I was merely countering your comment on exhibition layouts , which are sometimes out and back , or scenic break type layouts. In this case repeated circling of the layout to achieve near scale deacceleration would look odd and wrong.

 

Again Take a model railway that is signalled , berth and clearance distances will have need compromised significantly but trains still need to decelerate and still within the model signalling distances allowed. That's means far great deceleration and acceleration then the prototype. In fact prototypical rates would look distinctly wrong.

 

Nothing in this takes away from a good model chassis, but model crawl speeds are more a function of gearing and pickups ( and good level track ). While therm 141 is impressive m when I see it matched in a G class two axle diesel , I'll be seriously impressed. ( and across a dead frog peco to boot !!j