Scale Speeds

[stevieboy]

What is considered to be a 'good' slow speed (purely to test the loco's running qualities)?

I've managed to get around 3mph on DC from one of the Class 14's I had which seemed pretty slow.  Does DCC improve this further?

It can do. With a CT decoder my class 24 really doesn't have a bottom speed. It gets to the point where the decoder will pulse the motor minute amounts at a regular rate and it crawls at about one sleeper a minute.

If you are getting down to a scale 3mph I'm not sure less is useful unless you are modelling an MGR coal setup or something similar !

I think I just like having a benchmark for knowing how well the loco is run in and how well it's performing etc.  They'll hardly ever run that slow when I'm 'playing'.

[ToothFairy]

Just a thought: scale speeds are one thing; scale times are another. If your layout is to scale in terms of distance, you don't have a problem - but in most cases that means you are modelling a small section of a line. Here's the story for the rest of us:

If a real train travelling at a real speed of 60km/h gets from point A to point B in two real minutes, the real distance is 2km; that corresponds to a scale distance of 13.5 metres. On the model layout, the distance might be only one tenth of that, so the model system's "clock" must run ten times as fast. Then the model train, travelling at a scale speed of 60km/h (a real speed of about 0.4km/h), travels the 1.35 metres in 12 real seconds, but the model system's clock treats this real time as two minutes (120 seconds) of scale time. Stopping times at stations must also be adjusted, so that a reasonably realistic one-minute wait is reduced to a mere 6 seconds.

Unfortunately, the only supplier of clocks running at scale speeds that I ever found seems to have gone out of production.

- Michael

[edwin_m]

Scaling time can only ever be a compromise.  The time between stations can be scaled but the time spent at stations, shunting etc can't be to anything like the same extent.  To me a 6-second station stop would just look odd.  If you want scale time I think the solution is to go by the scale clock for station departure times but to ignore it for all other activities. 

[MacRat]

Unfortunately, the only supplier of clocks running at scale speeds that I ever found seems to have gone out of production.

JMRI can run a fast clock on your computer and send the time over LocoNet, if I understand it correctly.

[Agrippa]

I'm lost already As Einstein would say it's all relative.

I've had 10 mins with a calculator and pencil and paper and
I can't get it right. A model running x meters in y seconds
is travelling at x/y meters per second , that is real time,
the same applies to a real train or plane, so I don't think
you can convert  the model's real speed scalewise.
The answer is to control the model at a speed that looks realistic,
ie tank engines with a few wagons crawling along and HSTs etc
moving at 2-3 times as fast.
As edwin-m states some scale time would look odd (station example)
also points would switch so fast as to seem instantaneous.
This would make the use of slow acting point motors,
semaphores etc anomalous.

[edwin_m]

Let's assume your prototype (real or imagined) has two stations ten miles apart and a fastish train takes ten minutes from one to the other (60mph). 

Ten scale miles in N gauge is about 110 metres and few layouts will have that much track between stations.  But a largeish layout may have 11 metres or one scale mile.  But then a train doing a scale 60mph would only take one minute to get from one station to the next. 

You could therefore have a scale clock running ten times actual speed, so that going by this clock the train would take the correct 10min if it was running at a speed that looked realistic.  It would also mean that trains would run more frequently (an hourly service would run every 6min on the model) which is probably a good thing.  But as I said above, I think you would still make the station stop a real minute or so. 

The important thing is that the speed does not scale.  If you scaled the speed to take 10min between stations then the train would have to run at a scale 6mph instead, but that would not look very realistic. 

Other options would be to have some hidden track between the stations where the train can stop and wait, re-write the timetable so that the train is scheduled to have less time, not bother with a clock and just have a "sequence counter" which is moved on when all the events due in a particular step have been finished. 

[boffin22]

After seeing all the algebraic and applied mathematics formulae regarding scale speeds I think my (and perhaps others) calculus method is the best.
"If I think it looks right to me - it's right! Always willing to learn new tricks though!
David

[Sprintex]

Let's assume your prototype (real or imagined) has two stations ten miles apart and a fastish train takes ten minutes from one to the other (60mph). 

Ten scale miles in N gauge is about 110 metres and few layouts will have that much track between stations.  But a largeish layout may have 11 metres or one scale mile.  But then a train doing a scale 60mph would only take one minute to get from one station to the next. 

You could therefore have a scale clock running ten times actual speed, so that going by this clock the train would take the correct 10min if it was running at a speed that looked realistic.  It would also mean that trains would run more frequently (an hourly service would run every 6min on the model) which is probably a good thing.  But as I said above, I think you would still make the station stop a real minute or so. 

The important thing is that the speed does not scale.  If you scaled the speed to take 10min between stations then the train would have to run at a scale 6mph instead, but that would not look very realistic. 

Other options would be to have some hidden track between the stations where the train can stop and wait, re-write the timetable so that the train is scheduled to have less time, not bother with a clock and just have a "sequence counter" which is moved on when all the events due in a particular step have been finished.

You seem to be missing the point . . .

ALL WE ARE DOING IS PLAYING WITH TOY TRAINS !!



All this clock nonsense is complete overkill. Scale speed is just that: trying to make a train move at a roughly realistic speed rather than freight trains doing 120mph or Class 91 sets doing 160mph as mine will do if I turn it up to maximum. Let's not forget we have people that never go anywhere, cars that are mostly stationary in the middle of the road, and trains where the doors never open to let our glued-to-the-spot passengers on or off! Trying to get too clever with the time-space continuum is just taking the fun out of the hobby 


Paul

[Agrippa]

Messing about with the time-space continuum is not to be recommended, if you remember
the tv series Primeval. However from a model rail point of view it means you could justify
running Big 4 trains on a modern era layout by claiming they arrived via the anomaly,
also useful with the numerous changes in BR coach liveries post nationalisation.....

[edwin_m]

ALL WE ARE DOING IS PLAYING WITH TOY TRAINS !!

Which is fine and good, but not a reason to shout down a discussion just because you don't want to take part in it. 

[lionwing]

Got a bit puzzled by the mention of scale speeds in some publications/forums, especially as some imply it's a complicated process.

Am I correct in thinking that these are arrived at by simply dividing a mile (5280 feet) by 148 (for N of course) and  measuring the time a loco takes to cover a fixed distance e.g.

1 foot covered in 10 seconds or 6 feet in 1 minute = 10 MPH

5 feet covered in 10 seconds or 30 feet in 1 minute = 50 MPH

Or is there some other more complicated formula I should be using?

Thanks in advance.

Ray

Wow...by this measure with the controller all the way to the right my Dapol 0-6-0 Pannier can do 120mph!

Out of interest and assuming it is not pulling a load what would a 0-6-0 Pannier be capable of?

[EtchedPixels]

Out of interest and assuming it is not pulling a load what would a 0-6-0 Pannier be capable of?

Generally the real thing was limited to about 30mph. It depends on the wheel size. Some of the ones with larger wheels would top out about 45mph.

They were not fast beasties, but then most of the work they did was on branch lines that were rarely laid for fast running, or freight where fast running wasn't going to matter.

Steam locos are not generally geared so there is also a rather direct connection between acceleration, top speed and wheelsize that makes a tricky trade off. That's one reason DMUs could improve suburban services so much - even a first gen DMU had geared drive and far better acceleration.

[martink]

Out of interest and assuming it is not pulling a load what would a 0-6-0 Pannier be capable of?

On occasion, 14xx 0-4-2s were clocked doing at least 70mph.  Panniers have smaller driving wheels, so would be considerably slower.

[EtchedPixels]

9600 GWR 57xx Class 0-6-0 Pannier Tank - test run

might also be helpful - thats a larger pannier on test light engine.

[Agrippa]

Very good video, wee beastie fairly belting along.