RMweb Premium OnTheBranchline Posted February 22, 2014 RMweb Premium Share Posted February 22, 2014 Is there such a thing as a speedometer that you can connect to your layout to see how fast in terms of real speed each loco is running? Link to comment Share on other sites More sharing options...
Black Sheep Posted February 22, 2014 Share Posted February 22, 2014 Speed = distance / time Measure the distance, say 1 meter and time how long the train takes to travel it, To get scale distance the divide the result by your scale, eg 76 for 00 Someone will pop up in a bit to tell me I don't remember my physics homework properly... Link to comment Share on other sites More sharing options...
34theletterbetweenB&D Posted February 23, 2014 Share Posted February 23, 2014 Multiplication is actually the better method, as in metre on the layout is near 76 metres in reality. Folks have built themselves speedo wagons, using components from bicycle speedometers. There was thread on this site, or possibly in the precursor RMweb archive which you could search for. Link to comment Share on other sites More sharing options...
Coombe Barton Posted February 23, 2014 Share Posted February 23, 2014 Roughly, in 4mm, a foot per second is 52mph. 60mph is about 14 inches per second 30 mph -7 inches per second It 's slower than most people think Link to comment Share on other sites More sharing options...
Matt Posted February 23, 2014 Share Posted February 23, 2014 Nigel Burkin did an article about speedometers a couple of years back one of the mags, probably BRM? Was a plug in device with a digital readout of speed. Was thinking myself could be useful for dcc prog of max speeds... Sorry don't recall which mag but someone on here might... M Link to comment Share on other sites More sharing options...
jwealleans Posted February 23, 2014 Share Posted February 23, 2014 It must exist, Roy Jackson has (or had, at least) one on Retford. Link to comment Share on other sites More sharing options...
RMweb Gold Phil Bullock Posted February 23, 2014 RMweb Gold Share Posted February 23, 2014 http://www.cp4e.com/trsped.htm http://www.trainelectronics.com/speedometer/speedometer_manual.htm Heres a couple of options A nice idea! Cheers Phil Link to comment Share on other sites More sharing options...
Lightning Posted February 23, 2014 Share Posted February 23, 2014 (edited) A few years ago Roy Jackson tested & described an imported American digital speedometer on the Retford model. An article was featured in the Model Railway Journal when 60027 "MERLIN" attained the world speed record between Babworth and Retford (North). The Speedo is accurate & is still in use. Sorry I'm not sure which MRJ it is in. Still does. Morning Johnathan! ISSUE 159 Edited February 23, 2014 by Lightning Link to comment Share on other sites More sharing options...
atticombe Posted February 23, 2014 Share Posted February 23, 2014 Is there such a thing as a speedometer that you can connect to your layout to see how fast in terms of real speed each loco is running? Black Cat Technology produce a wagon cable of measuring he relative speed in either miles or kilometres per hour. Only problem is they are in rather short supply, see web site http://www.blackcattech.co.uk Link to comment Share on other sites More sharing options...
Bill Radford Posted February 23, 2014 Share Posted February 23, 2014 Roughly, in 4mm, a foot per second is 52mph. 60mph is about 14 inches per second 30 mph -7 inches per second It 's slower than most people think There was an article in RM in the 80s with a table which expanded on this - it's somewhere around but it will mean plowing through all the old copies underneath the layout so may take some time.... Link to comment Share on other sites More sharing options...
Coombe Barton Posted February 23, 2014 Share Posted February 23, 2014 There was an article in RM in the 80s with a table which expanded on this - it's somewhere around but it will mean plowing through all the old copies underneath the layout so may take some time.... The table is easy to rebuild using a spreadsheet. Does anyone want it? 2 Link to comment Share on other sites More sharing options...
RMweb Premium Ray H Posted February 23, 2014 RMweb Premium Share Posted February 23, 2014 A slightly expanded table would be useful although as has been suggested I could probably work something out in Excel. I wonder how accurately enough we can measure time to get other than a fairly basic idea of the speed especially as I presume the time has to be measured between two fixed locations with the loco already travelling at the desired speed when it passes the first and not starting from stationary. I think it may require some electronics to do the job properly. Link to comment Share on other sites More sharing options...
Il Grifone Posted February 23, 2014 Share Posted February 23, 2014 I use a stop watch (cheap these days) and a fixed, measured distance. It's quite easy to get reliable results on a continuous circuit, but point to point layouts will have problems (especially small ones). Before the introduction of speedometers, the usual way to measure speed was the time between quarter mile posts. (Sherlock Holmes used the distance between telegraph poles in one of the stories, but the likelihood of these being 100% consistent is low IMHO.) Link to comment Share on other sites More sharing options...
34theletterbetweenB&D Posted February 23, 2014 Share Posted February 23, 2014 There is an error associated with all measurement techniques, so the results should always be expressed as a value with error range. But really in modelling does it matter so much? If the speed is within 10% of 'truth' and the relative speeds of different movements are maintained, as in the 110kph max train goes at half the rate of the 225kph capable train when both are running at full speed, that will do. Where our movement modelling is often seriously adrift is in acceleration. I have seen many otherwise well modelled layouts demonstrate accelerations that belong only in motor sports or on aircraft carrier decks. Link to comment Share on other sites More sharing options...
corax67 Posted February 23, 2014 Share Posted February 23, 2014 If you want something you can simply drop onto a layout then you might like to consider the MRT Accutrack speedometer: http://store.sbs4dcc.com/modelrailroadtechnologiesaccutrackspeedometer.aspx Its a battery powered speed trap with a neat LED display - might be a quick fix for you. Link to comment Share on other sites More sharing options...
Coombe Barton Posted February 23, 2014 Share Posted February 23, 2014 Approximate speed calculator for common scales. Approximate Prototype speed calculator for common scales.pdf 2 Link to comment Share on other sites More sharing options...
RMweb Gold Phil Bullock Posted February 23, 2014 RMweb Gold Share Posted February 23, 2014 There is an error associated with all measurement techniques, so the results should always be expressed as a value with error range. But really in modelling does it matter so much? If the speed is within 10% of 'truth' and the relative speeds of different movements are maintained, as in the 110kph max train goes at half the rate of the 225kph capable train when both are running at full speed, that will do. Noooooooo!!!!! Spent last week on an ISO15189 course - spent a whole afternoon on uncertainty of measurement Came on here to return to sanity. Phil Link to comment Share on other sites More sharing options...
Il Grifone Posted February 23, 2014 Share Posted February 23, 2014 Noooooooo!!!!! Spent last week on an ISO15189 course - spent a whole afternoon on uncertainty of measurement Came on here to return to sanity. Phil Only an afternoon? Tolerances are fundamental in engineering..... 1 Link to comment Share on other sites More sharing options...
Bill Radford Posted February 23, 2014 Share Posted February 23, 2014 (edited) Approximate speed calculator for common scales. Approximate Prototype speed calculator for common scales.pdf Thanks - I managed half a dozen RMs but ended up rereading the articles!! If you've got this month's, there is an article on lever frames - a repeat from one I read this afternoon!! Edited February 23, 2014 by Bill Radford Link to comment Share on other sites More sharing options...
RMweb Gold Phil Bullock Posted February 24, 2014 RMweb Gold Share Posted February 24, 2014 Only an afternoon? Tolerances are fundamental in engineering..... Well - there's a high degree of probability that it was a period of time somewhere between 3hrs 40 and 3 hrs 50 minutes long....!!! Havent calibrated my watch recently however so that statement may not stand scrutiny. Phil Link to comment Share on other sites More sharing options...
34theletterbetweenB&D Posted February 25, 2014 Share Posted February 25, 2014 Which is why you don't want to get over-excited over the absolute value of the scale speed you are operating at. To take a steam age example, if your unfitted heavy is plodding along somewhere between 20 and 25mph on the running lines, that's going to look OK. What will look wrong though, is the all too frequently seen acceleration from that running speed to rest in about three seconds. It needs a minute or more to be realistic. Even the crappiest timekeeper won't affect that representation: it could be guessed at with a sand flow egg timer! Link to comment Share on other sites More sharing options...
bike2steam Posted February 25, 2014 Share Posted February 25, 2014 Yeah, but there again if 'modellers' took more notice of scale speeds maybe fewer would get over-excited about noise generated by baseboards - just a thought !! Link to comment Share on other sites More sharing options...
xdford Posted February 26, 2014 Share Posted February 26, 2014 (edited) I use Spikes on my layout spaced out at 5 inch intervals. In HO, 5 inches travelled in 5 secs - 5 mph, 10 inches in 5 seconds is 10 mph etc. My spikes are painted with every fourth one a different colour to represent the 20mph marks. You can change the spike spacing to 5.75 inch spacing in OO or 2.75 inch for N scale. The spikes represent survey pegs that are usually left to rot for many years but quite obvious. The faster you go, the more pegs you cover in 5 seconds in multiples of 5 mph which is what most speed limits have. I have a full story about the idea on http://xdford.digitalzones.com/modelrr10.htm but as my server does not like hot linking, you will have to copy the site manually onto another aspect of the browser. Hope this helps Regards from Oz Trevor Gibbs Melbourne Australia Edited February 27, 2014 by xdford Link to comment Share on other sites More sharing options...
RJS1977 Posted February 27, 2014 Share Posted February 27, 2014 Roger Penfold's (first) book on model railway electronics contains a speedometer circuit. Link to comment Share on other sites More sharing options...
RMweb Gold Phil Bullock Posted March 12, 2014 RMweb Gold Share Posted March 12, 2014 (edited) Here is a relatively straightforward Excel file you can use to calculate speed Just input your scale and track distance you wish to measure over and you will get an indication of the number of seconds to travel that distance in your chosen scale Bullock's patented scale model relative velocity calculator.xlsx Feel free to download and have fun - no speeding! Phil Edited March 12, 2014 by Phil Bullock Link to comment Share on other sites More sharing options...
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