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Old 05-05-2018, 04:26 PM   #1
Bunkerbarge
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Default A Question of Speed

One thing I have been pondering specifically recently is the challenge of locomotive speed and trying to establish something a little bit less hit and miss and a bit closer to realistic than I get out of the box with L1s and J15s screaming around the layout significantly faster than the A4s!! We can all adjust the speed either by setting the limits in DCC or simply not going beyond a certain mark on the DC controller but I wanted to know exactly what the speeds were I was seeing and how they compared with reality.

So I have done a bit of research and set myself up with a test set up that I realise may be of use to other members here. The thinking started first of all with how to measure the speed of the locomotives on the layout and realising that I needed something along the lines of a measured mile. Near as makes no difference I soon estimated that 2.1 metres actually works out at close enough to 1/10th of a mile at 1/76th scale, which certainly sounded handy. Consequently I marked out a 2.1 meter stretch of straight track with some frog tape. Next I played around with some numbers and decided to put together a simple table which gives you a real life speed for a timed run of the 2.1 meters section of track. Consequently if my loco takes six seconds to complete the 2.1 meter stretch, i.e. 1/10 th of a real mile, then it would be doing a scale speed of 60 mph. The rest of the table therefore followed accordingly:

Time Real Speed
(Secs) (mph)

5.0 72.0
5.1 70.6
5.2 69.2
5.3 67.9
5.4 66.7
5.5 65.5
5.6 64.3
5.7 63.2
5.8 62.1
5.9 61.0
6.0 60.0
6.1 59.0
6.2 58.1
6.3 57.1
6.4 56.3
6.5 55.4
6.6 54.5
6.7 53.7
6.8 52.9
6.9 52.2
7.0 51.4
7.1 50.7
7.2 50.0
7.3 49.3
7.4 48.6
7.5 48.0
7.6 47.4
7.7 46.8
7.8 46.2
7.9 45.6
8.0 45.0
8.1 44.4
8.2 43.9
8.3 43.4
8.4 42.9
8.5 42.4
8.6 41.9
8.7 41.4
8.8 40.9
8.9 40.4
9.0 40.0
9.1 39.6
9.2 39.1
9.3 38.7
9.4 38.3
9.5 37.9
9.6 37.5
9.7 37.1
9.8 36.7
9.9 36.4
10.0 36.0


For me with DCC all I now have to do is to adjust the limit on the decoder via the control unit to give me the time I am looking for. I have decided to work to around 30 mph for goods traffic, 30-40 mph for suburban passenger lines and 40-50 mph for main line with the A3s and A4s going up to 60-70 mph. Very approximately!!

For this to be useful to anyone else modelling OO gauge all you need to do is set up two points on your track exactly 2.1 meters apart (figures, buildings, vehicles, signals etc), time your locos through them and see what the scale speed is from the table above. For example if your loco took 9.4 seconds to cover the 2.1 metres then its real time speed would actually be 38.3 mph.

My J15 and J50 now chuff around considerably more realistically.
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Old 05-05-2018, 04:30 PM   #2
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To be honest running a loco at say a scale speed of 70mph is not in my view the thing to do. I go by the old adage if it looks right it is right. An OO express at a scale 70mph may look much too fast on my layout and slow on yours. Not everything is scaled down by 1:76.
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Old 05-05-2018, 05:15 PM   #3
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Quote:
Originally Posted by Walkingthedog View Post
To be honest running a loco at say a scale speed of 70mph is not in my view the thing to do. I go by the old adage if it looks right it is right. An OO express at a scale 70mph may look much too fast on my layout and slow on yours. Not everything is scaled down by 1:76.
I fully agree it would not look right going through a station or a junction at that speed. However I actually said "Going up to 60 or 70", that's just a range for a limit not a requirement.

I only shared the table with those who might find it equally useful to determine just what speed they are doing. It may interest some.

Last edited by Bunkerbarge; 05-05-2018 at 05:16 PM.
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Old 05-05-2018, 05:23 PM   #4
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Speed in model form is a fascinating subject.
For me it is about the impression one gets when one sees the locomotive pass by. Sometimes a locomotive can pass at an exact scale speed, but maybe look too slow compared to how those who view the model expect it to go.
A particular issue comes to light when one has either a shunting layout, or one is modelling a narrow gauge prototype. If I tried to run my narrow gauge locos to a scale speed, then either they would bore any viewers (Myself included!) or they would risk stalling. The compromise for me is to have them trundle along at a speed which suits the motor and the eye of the viewer.
The perception of speed can be adjusted according to what is being run while ignoring the scale speeds for greater effect. A lengthy express train on a large layout has the excuse to run flat out or close to that speed so one emphasises the speed of the express. It is a bit like the artists impressions of a speeding locomotive when if one took a photograph for comparison one would be disappointed. Yet the painting captures the thrill of the moment.

What tends to look odd, is a little shunting engine zooming past an express passenger train at full tilt!

One of the most thrilling trains I have heard that captures this effect almost like no other is the sight and sound of a Hornby Dublo 3 rail express locomotive thundering by with a lengthy train of tinplate coaches on tinplate rails. I've not had anything in model form that captures the thrill of an express passenger train quite like it. It may not look realistic, but it gives the viewer a real feel of what it was like to watch a real express steam locomotive and its train of coaches thunder past.
Thanks for sharing the table. It is appreciated. No doubt different scales one will need a different table of speeds.

There used to be a scale speed indication device available to check passing model trains. If you can get hold of one, you may find it useful.

Last edited by Mountain Goat; 05-05-2018 at 05:33 PM.
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Old 05-05-2018, 05:27 PM   #5
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In wasnít knocking what youíve done I did a similar thing some years ago. Thatís when I realised that sometimes a scale speed just isnít right. Ones of the joys of this great hobby.
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Old 05-05-2018, 05:50 PM   #6
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I agree with everything said gents. As I suspect you did I found it very interesting to see what my own perception of speed was compared to what it was in reality. I will still of course favour what looks right but I also like to know what the numbers are for comparrisons.

In my case with DCC and sound it is also very important to me that it sounds right. I have taken a lot of care over timing the chuffs correctly to match number of cylinders etc to get the most realistic effect in a complete revolution of the wheels so I want to enjoy these sounds at slower rather than faster speeds.

As an interesting aside I was very close to the Flying Scotsman only a couple of weeks ago going past a a fairly fast speed. I was very surprised at how quickly it passed with a full length train behind it. I was stood at a local country crossing barrier so pretty close. It was very noticeable that you could not distinguish individual chuffs and, interestingly, she was making no smoke or steam so combustion must have been pretty spot on.
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Old 05-05-2018, 05:56 PM   #7
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I never forget two 4MT locos double headinga steam special. I only saw it by chance. They were much quieter then I expected them and very little smoke, even though they were pulling away.
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Old 05-05-2018, 06:13 PM   #8
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They make very little noise particularly when coming into a station. That can be one of the problems with sound steam locos chuffing away as they coast into a station and stop.
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Old 05-05-2018, 06:43 PM   #9
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That is controllable, WTD, all the steam sound decoders have the option to run the coasting sound instead of the chuff including TTS.......just a matter of remembering to activate the function #......my Econami decoder has a very realistic con rod clank on deceleration.....you really would enjoy it on your layout........HB
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Old 05-05-2018, 07:04 PM   #10
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Have to say it is one of the things I have noticed at shows, constant chuffing which isnít realistic. Diesels sound better but only a tiny bit. Nothing sounds best of all.
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