Calculating the scale speed of OO gauge models

[The Johnster]

I operate a BLT to real time, so don’t have to worry about time compression in the way that Dungrange does.  The working timetable simply makes an time allowance for different classes of train to run to the junction and the signalmen to block back and exchange tokens with the drivers, which determines the minimum actual time that must elapse before the next train appears from the fiddle yard.  
 

‘Cwmdimbath Time’ is shown on a battery master clock that can be switched on during running sessions; no running is allowed when it is switched off, and it runs at normal speed when it is switched on.  This has nothing to do with scale speeds, and Cwmdimbath Time is real, not scale, though can be stopped.  The challenge is to complete the more complex shunting in the times allowed by the WTT at reasonably realistic speeds before the next incoming train arrives, assisted by an offstage imaginary outer home and advance starter signal.  If the next train is delayed offstage at the outer home by overrunning shunting, a knock on effect will delay traffic on the single line section for some time afterwards, and ‘stopping the clock’ to catch up is cheating. 

[Berkshire Steam]

New member here.    run a large layout in a double garage and I try to run trains at speeds that look "authentic". I run an extensive service of both passenger, parcels and freight traffic. Most passenger trains run at scale 60mph which is a 45 second circuit. 75mph is 40 seconds and 90mph is 35 seconds. Running a model railway in the manner that I do, if it looks right, then it is right and I think I've just about got it right!  I subscribe to the clickety click method to gain a realistic looking speed 

Not very scientific but heyho, it works for this layout!

Nick

 

 

[Dungrange]

5 minutes ago, The Johnster said:

I operate a BLT to real time.

 

Which is the way it should be if you are only modelling one station that is roughly to scale (ie not much linear compression).  The notion of adjusting the rate of the the passage of time really only becomes an issue for those who model multiple stations, compress the distances between them and then want the trains to arrive / depart from each station according to the time on a clock.

[wasdavetheroad]

50 minutes ago, The Johnster said:

I operate a BLT to real time, so don’t have to worry about time compression in the way that Dungrange does.  The working timetable simply makes an time allowance for different classes of train to run to the junction and the signalmen to block back and exchange tokens with the drivers, which determines the minimum actual time that must elapse before the next train appears from the fiddle yard.  
 

‘Cwmdimbath Time’ is shown on a battery master clock that can be switched on during running sessions; no running is allowed when it is switched off, and it runs at normal speed when it is switched on.  This has nothing to do with scale speeds, and Cwmdimbath Time is real, not scale, though can be stopped.  The challenge is to complete the more complex shunting in the times allowed by the WTT at reasonably realistic speeds before the next incoming train arrives, assisted by an offstage imaginary outer home and advance starter signal.  If the next train is delayed offstage at the outer home by overrunning shunting, a knock on effect will delay traffic on the single line section for some time afterwards, and ‘stopping the clock’ to catch up is cheating. 

I remember a famous modeller doing that at an exhibition, 'when is the next train due' I asked. 'in 45 minutes' he replied. 'nice trees' i said, backing away rapidly 

 

As for scale speeds, 31 seconds around the UP Main is scale 60 mph on my layout, everything is simple after that. I cheat of course, unfitted freights are about 60 seconds not 74.4 seconds 

Edited April 18, 2021 by wasdavetheroad

[frobisher]

4 hours ago, mikesndbs said:

There seems to be as many ways of doing this as members in the forum!

 

There must be a set formula taking the knowns of scale 1/76th distance and time in seconds.

 

LOL I am more confused than when I started. Easily done I guess

 

The key is to pre-can your calculation.  Do the hard bit once and correctly.

 

Time your trains (in seconds or elephants because let's face it we really only work to integer seconds most of the time anyway...) through the same bit of track of a known length (say 5 120g Cadbury Dairy Milk bar lengths) but as it's always the same easily discernible length of track this is a fixed value rather than try and determine a length over a fixed time (trickier),

 

If you travel that length in a single elephant then that gives you a speed of 5 CDM per elephant (if you travel that length in 2 elephants then it's 5/2 or 2.5 CDM per elephant)

 

You've got your pre-canned calculation that the 1 CDM per elephant is 21.95 "00" miles per hour (this is the calculation you need to do once and the input units, imperial, metric or chocolatey are irrelevant to the outcome...).

 

So multiply that by your choccy elephant speed to get

 

5 times 21.95 = 109.75 "00" mph or 54.875 "00" mph for your 2 elephant transit.

[The Johnster]

I wouldn't recommend real time for an exhibition layout, for the reason wasdavetheroad has pointed out (and I reckon I could identify the modeller in question...).  Some layouts represent the sort of goods yards that were visited once a week as required!  At home, of course, there is no objection to manually bringing the master clock's hands forward to condense 'dead' time in quiet periods, and I have removed the glass to enable this, but in practice I often don't; I am quite happy to use the time to potch about with minor projects or repairs or, sometimes, just sit and soak the atmosphere with a can of Guiness.  The WTT has a period of 90 minutes dead time in the evening, and I sometimes use this for a returning seaside excursion or a pigeon special, but I do fast forward the hands for this as well.

 

 

[AndrueC]

I don't have a problem with station arrival times. My layout doesn't have any stations

[Philou]

1 hour ago, The Johnster said:

Some layouts represent the sort of goods yards that were visited once a week as required!

 

I suppose if you were really cheeky, you could turn up at an exhibition with a goods yard with plenty of stock (but no locos). 'When's the next train, then?' 'None, closed on weekends'.

 

Well, the thought made me laugh anyway (bored at the mo').

 

Cheers,

 

Philip

Edited April 18, 2021 by Philou

[The Johnster]

2 hours ago, frobisher said:

 

The key is to pre-can your calculation.  Do the hard bit once and correctly.

 

Time your trains (in seconds or elephants because let's face it we really only work to integer seconds most of the time anyway...) through the same bit of track of a known length (say 5 120g Cadbury Dairy Milk bar lengths) but as it's always the same easily discernible length of track this is a fixed value rather than try and determine a length over a fixed time (trickier),

 

If you travel that length in a single elephant then that gives you a speed of 5 CDM per elephant (if you travel that length in 2 elephants then it's 5/2 or 2.5 CDM per elephant)

 

You've got your pre-canned calculation that the 1 CDM per elephant is 21.95 "00" miles per hour (this is the calculation you need to do once and the input units, imperial, metric or chocolatey are irrelevant to the outcome...).

 

So multiply that by your choccy elephant speed to get

 

5 times 21.95 = 109.75 "00" mph or 54.875 "00" mph for your 2 elephant transit.

This will only work on trunk routes, of course...

 

Taxi?

[AndrueC]

7 hours ago, melmerby said:

As i said in my first post. But it does need scaling.

 

As to converting from metric to imperial. Why use metric in the first place?

Perhaps because imperial units are defined in terms of metric? Why complicate things by calling 25.4mm 'an inch'?

 

25.4mm is..25.4mm. Making up names for an arbitrary distance seems unnecessarily complicated.

 

https://en.wikipedia.org/wiki/Inch

 

"Standards for the exact length of an inch have varied in the past, but since the adoption of the international yard during the 1950s and 1960s, it has been based on the metric system and defined as exactly 25.4 mm."

 

And, posting as an N gauge modeller (where the 'N' stands for 'nine' as in 'nine millimetres)', I fail to see any reason to involve deprecated and obscure units.

Edited April 18, 2021 by AndrueC

[melmerby]

2 minutes ago, AndrueC said:

 Why complicate things by calling 25.4mm 'an inch'?

 

 

Why complicate an imperial inch by calling it 25.4mm when you are only using imperial units?

It's only 25.4mm to have a direct connection with standard metric units.

 

We are generally using historical items which were designed with the imperial system and are measuring in the imperial system.

Converting to 25.4mm is utter stupidity.

 

N.B. as I mentioned earlier I am 100% metric apart from such things that were imperial and still are imperial.

Some of this complication by bringing in metric conversion strikes me as peoples lack of ability to swap units as necessary.

If something was made metric, I will work in metric, if it was imperial, I still work in imperial.

Starting a project from scratch I will use metric.

 

Until such times as many industries become truly metric, imperial is here to stay.

Pint, Gallons, Miles etc. IMHO we should have gone fully metric 30+ years ago No more pints or miles

 

The building industry is one of the worst offenders.

Do you go to the woodyard and ask for a 2440mm x 1220mm plywood board? No it's 8' x 4' even though marked 2440 x 1220

These are not metric sizes, they are the metric conversion of existing imperial sizes, they should be 2m x 1m or such.

[Michael Hodgson]

4 hours ago, wasdavetheroad said:

I remember a famous modeller doing that at an exhibition, 'when is the next train due' I asked. 'in 45 minutes' he replied. 'nice trees' i said, backing away rapidly 

I've been to some shows where that attitude prevails ... it's lunch time and the bar is open.

 

I was a member of a club once whose members always grumbled about taking their layout to exhibitions.   "We only hold one because  we have to make some money to keep the annual subs down".  They didn't factor into it the cost of hiring the hall or the cost to the members (who weren't paid any expenses) of getting the stuff and themselves there and attracting other clubs to attend.  Looked at purely financially, it would have been cheaper to put up the subs. 

[The Johnster]

My old club (we parted company a long time ago) had a similar attitude; ‘we build layouts to take to shows to generate income to build layouts to take to shows’.  And so the long night wore on, and then we got involved in promoting a local show, so the main driver became the show’s profitability. There was little modelling off trains, but I learned a bit about baseboards and track laying.  The clubrooms were a series of cheap but semi-derelict and unheated premises, and mostly resembled a badly managed woodworking shop.  The layouts were mostly unfinished and could not be operated properly. 
 

The social side, going over the pub afterwards, was the best bit and why I stayed so long.  The shows were frankly unremitting and thankless hard work and stress and I came to hate them, attending mainly for the opportunity to buy bits from traders’ stalls.  Any perceptible willingness to operate a layout meant that you were stuck there unrelieved for hours once the bar opened as there were never enough members to man the layouts properly, then complained about for lack of commitment when you managed to get away for a sarnie and a quick pint yourself.  There was no other local club open to new members, and of course I eventually stopped being taken for a mug and left.  
 

A hobby is supposed to be what you do for enjoyment, but this turned into a bit of a grind. 

[Dungrange]

23 minutes ago, melmerby said:

Converting to 25.4mm is utter stupidity.

 

Unless of course you think of speed in kilometres per hour, in which case measuring the distance on the model in millimetres makes sense (but then you don't need to consider, inches, feet, yards or any other imperial measurement nor conversion factors between imperial and metric units).

 

However, I agree that if you want to calculate the speed in miles per hour (which are imperial units) then it makes sense to use imperial measurements on the model (ie feet or inches) and retain imperial units throughout the calculation.  The exception being the need to mix metric and imperial units to determine the scale (assuming you are working in 4mm scale - ie 1:76.2 or any of the other scales with hybrid units).

 

 

[Colin_McLeod]

Why not model Irish Rail?

 

Prototype track gauge 1.6m

Scale 1 in 76.2

Model track gauge 21mm

 

Speeds in km/h

 

 

 

[frobisher]

1 hour ago, Dungrange said:

However, I agree that if you want to calculate the speed in miles per hour (which are imperial units) then it makes sense to use imperial measurements on the model (ie feet or inches) and retain imperial units throughout the calculation

 

Whatever you do, you will have scale and conversion factors though, so it is perfectly acceptable.  If you pre-can the majority of the calculations, it doesn't matter what your input and output units are.

[Philou]

IMHO where 1:76.2 scores best using the 4mm/ft scale, is that you can use any old ruler even the old school wooden ones (remember them across your knuckles?) and provided there are mm graduations, you can immediately produce a scale drawing from an imperial scaled one. Now try that in 0 or H0 .........

 

(Added: working in 4s is simpler than in 7s, IMHO)

Edited April 18, 2021 by Philou

[Michael Hodgson]

14 minutes ago, Philou said:

IMHO where 1:76.2 scores best using the 4mm/ft scale, is that you can use any old ruler even the old school wooden ones (remember them across your knuckles?) and provided there are mm graduations, you can immediately produce a scale drawing from an imperial scaled one. Now try that in 0 or H0 .........

 

(Added: working in 4s is simpler than in 7s, IMHO)

Sounds like you deserved the ruler over your knuckles a bit more often for not learning your seven times table!

[NIRCLASS80]

Easy, use this calculator 

 

https://www.modelbuildings.org/scale-speed-calculator/

[kevinlms]

6 hours ago, The Johnster said:

My old club (we parted company a long time ago) had a similar attitude; ‘we build layouts to take to shows to generate income to build layouts to take to shows’.  And so the long night wore on, and then we got involved in promoting a local show, so the main driver became the show’s profitability. There was little modelling off trains, but I learned a bit about baseboards and track laying.  The clubrooms were a series of cheap but semi-derelict and unheated premises, and mostly resembled a badly managed woodworking shop.  The layouts were mostly unfinished and could not be operated properly. 
 

The social side, going over the pub afterwards, was the best bit and why I stayed so long.  The shows were frankly unremitting and thankless hard work and stress and I came to hate them, attending mainly for the opportunity to buy bits from traders’ stalls.  Any perceptible willingness to operate a layout meant that you were stuck there unrelieved for hours once the bar opened as there were never enough members to man the layouts properly, then complained about for lack of commitment when you managed to get away for a sarnie and a quick pint yourself.  There was no other local club open to new members, and of course I eventually stopped being taken for a mug and left.  
 

A hobby is supposed to be what you do for enjoyment, but this turned into a bit of a grind. 

So would it have worked out, if there were no bars?

 

It's virtually unknown for an exhibition in Australia to have a bar in the building.

[The Johnster]

It has been a long time since I've been to a model railway show here that had a bar.  Costs at the purpose built venues have risen and most shows are now held in schools, leisure centres, and the like.  The really big shows are in places like the NEC, which have full facilities, but I'm not good at crowds and those days are over for me!

 

 

[AndrueC]

16 hours ago, melmerby said:

Why complicate an imperial inch by calling it 25.4mm when you are only using imperial units?

It's only 25.4mm to have a direct connection with standard metric units.

I'm not 'calling it' 25.4mm. That's what an inch is. If you are a proponent of the imperial system then you ought at least to understand that. The entire imperial system is defined using the metric system and has been for nearly half a century. My complaint would be why divide things into multiples of 25.4mm in the first place? 25mm or 20mm is a more sensible size for 'things whot I can hold in my hand' . Everything in the world is now measured in metric it's just that a small proportion of humanity such as yourself choose to use alternative and often confusing terms when measuring things.

 

But I fear we're moving off topic here and for personal use it doesn't matter much. Using what you're comfortable with and have the tools for is the best solution there. I still use imperial for driving and - at the moment - golf. Though I keep saying I'll change the latter just as soon as I feel that it won't adversely impact my game, lol.

Edited April 19, 2021 by AndrueC

[Foden]

I subconsciously note how many sleepers disappear under my trains as they pass, and scale my control from there.

 

No equations, no fancy gizmos, blissful happiness. 

[The Johnster]

I use Imperial for weights and distances, and Fahrenheit for temperature, because those units are embedded in my brain, and I think in them.  If somebody describes a thing as 15 feet long I can visualise that instantaneously, and I know straight away how an air temperature of 65 degrees Fahrenheit will feel in a 25mph breeze.  
 

I an starting to be able to do this with Celsius temperatures now after living with the Squeeze, who is Polish, for 3½ years.  Metric weights and distances are proving more resistant!  Metric is a far more logical system and easier to work with, and I do find it convenient to use millimetres and centimetres in modelling, as I understand the concept of 4mm representing a foot better than the fraction of 1/76th, but when it comes to kilometres I have to stop and do a rough mental conversion, and kilograms mean nothing to me.

 

Grams I can work with but prefer ounces and pounds.  I’d probably manage better if there was a centigram unit but the jump from gram to kilogram fazes me. 

Edited April 19, 2021 by The Johnster

[melmerby]

1 hour ago, AndrueC said:

I'm not 'calling it' 25.4mm. That's what an inch is. If you are a proponent of the imperial system then you ought at least to understand that. The entire imperial system is defined using the metric system and has been for nearly half a century. My complaint would be why divide things into multiples of 25.4mm in the first place? 25mm or 20mm is a more sensible size for 'things whot I can hold in my hand' . Everything in the world is now measured in metric it's just that a small proportion of humanity such as yourself choose to use alternative and often confusing terms when measuring things.

 

But I fear we're moving off topic here and for personal use it doesn't matter much. Using what you're comfortable with and have the tools for is the best solution there. I still use imperial for driving and - at the moment - golf. Though I keep saying I'll change the latter just as soon as I feel that it won't adversely impact my game, lol.

You clearly do not know/understand standards.

The imperial system was defined long before it was aligned with the metric system and as such the "standard" inch has to be measured against a standard Metric unit, it cannot arbitrarily be changed to 25mm or 20mm That would be confusing.

BTW the prototype metre and prototype kilogram and the cgs system originated in the UK in Victorian times!

 

We started the metric journey back then in Victoria's reign but the bus seems to have broken down and hasn't moved for ages.

 

Metric is still not universal (although IMHO in most cases it should be)  and there are at least 22 countries which are not fully metric.

Marine navigation still uses knots for speed, Aircraft elevation is in feet (there is a reason)

UK/USA roads and railways still generally use miles & mph as do Canadian railways. There are many other cases throughout the world where non metric units are still used.

 

I work in metric and have done from early in my work career which started in the 1960s but I'm savvy enough to realise that if something was made in an imperial size, converting it's dimensions to metric to work on it is folly.

 

The UK building industry is very good at mixing it's systems, I have some timber products on order, the size is quoted as 4' x 225mm

Timber boards are still 8' x 4' but quoted as 2440 x 1220mm

 

 

Edited April 19, 2021 by melmerby