How do you measure scale mph in HO?

[DR DENNIS GORDAN]

In the 1950's the New York State Thruway warned drivers that, at 60 mph, the limit at the time, a car was traveling 88 feet per second, so don't tailgate. Anyway, that means, since HO is 1/87 full size, one actual foot per second is virtually 60 scale miles per hour, each foot per minute is a scale mile per hour, each inch per second represents 5 scale mph.

[Wolf359]

That looks pretty easy to set up. I have a chart that shows HO scale feet that I'll have to dig out.

[ndaily]

Here's another way to measure speed.  Set two markers 176 scale feet apart and use this chart:

MPH	5	10	15	20	30	40	60
sec.	24	12	8	6	4	3	2

Cheers!
Nathan

P.S. just to be clear, the number of seconds to go between the two markers will give you MPH. -N

[bearman]

Using an Accutrack II speedometer, I measured the scale velocity for a range of speed steps with a PowerCab throttle.  The relationship is not necessarily linear and I suspect that it is decoder and/or weight of the locomotive dependent.

[garya]

For our friends who use the Metric system, I came up with the following formula:

(.0357 X Scale Factor X Distance in Centimeters) / Time in Seconds=

Speed in Kmph

If you want meters for your distance, use 3.57 as your multiplier.

Scale factors are the same, 160, 87, etc.

[pomilian]

 For anyone interested, I have built two different speedometers based on the Arduino. One is stationary and built as a passthru over the tracks; The other is a rf transmitter unit that rides in a car and a handheld receiver display.

If interested in building something like this, please contact me off-line for more information. 

pomilian(at)sbcglobal(dot)net

Paul O

[bearman]

tstage

 

 

bearman

This thread begs a question.  Are the speed steps on a DCC system linear? For example, is step 6 double the speed of step 3?

 

They can be if that is the default of the OEM decoder.  More than likely it will be slightly exponential - i.e. with a gradual slope at the beginning (Vstart) and end (Vmax) of the speed table and a sharper one nearer the middle (Vmid).

Tom

 

 

Based on your response, I consulted the BLI Paragon3/2 manuals.  There is an interesting graph, identified as Motor Speed Curve, voltage vs speed step.  The factory default shows a linear relation between voltage and speed step, which leads me to believe that there is a linear relationship between speed step and locomotive velocity if the default is not fiddled with, at least for these two decoders.

[RailfanS]

One option that I haven’t seen mentioned yet is a different product from boulder creek engineering. It’s called their RollBy speedometer and consist of a board to be mounted in a car and an phone or tablet app. Although it’s more expensive than the measured distance and stopwatch method but I find it pretty useful for speed matching. I made a review on it recently: 

RollBy Scale Speedometer Review/ How I DCC Speed Match
https://youtu.be/W1F_A-l12xI

[jrlyman]

I have been using an Excel Spreadsheet which I created. One can select ANY length of track (in inches), use a stop watch to measure the time for the train to traverse that selected distance, and read the train speed in miles per hour directly from the chart. I believe that my method is easier to use than any of the methods shown here. I don't know how to put it into this forum but will email a copy to anyone who asks. I can email you the Excel spreadsheet or a printout of ANY selected distance that you choose. All you will need is a stopwatch. I use various easy-to-generate printouts of my method quite often.

http://[e-mail]

[tstage]

bearman

This thread begs a question.  Are the speed steps on a DCC system linear? For example, is step 6 double the speed of step 3?

They can be if that is the default of the OEM decoder.  More than likely it will be slightly exponential - i.e. with a gradual slope at the beginning (Vstart) and end (Vmax) of the speed table and a sharper one nearer the middle (Vmid).

Tom

[Spalato68]

This is interesting question. I have never measured it, but it can be checked relatively easy, measurng several "control points" on a speed curve. 

Hrvoje

[bearman]

This thread begs a question.  Are the speed steps on a DCC system linear? For example, is step 6 double the speed of step 3?

[xdford]

A few months ago, I placed a number of telegraph poles so that they aligned with the track centres at 10 inch spacing.

The idea was based on my scale speed method where a train passing a set distance in a given time. In HO scale, the distance in inches that a train covers in 5 seconds is equal to the scale miles per hour. Davidmurray is correct and I also use inches travelled in 5 second intervals.

 

I was using a set length of track at first then using spikes as a model of equally spaced siting pegs placed at 5 inch intervals.

With the layout renovation after the move, I have been back to using the length of track which at 38 inches gives me 35 smph just short of the length in 5 seconds, 40 just over. It was virtually a speed trap but just at the front of the layout.

At the back and around the rest of the layout, a few months ago I installed a number of Telegraph poles. These poles are aligned with 10 inch spacing at the track centre. Therefore they are not totally geometric in their spacing given that they are on the convex and concave sides of the curves around the back of the layout.

Here is 1404/1909 Westbound on a through freight starting a sectional count.

5 Seconds later they are just over 4  poles away so the train is doing about 41-42 smph!

 

I merely count 5 seconds out and you will be surprised how well you can do this. Each of the poles is equal to 10 smph for each on covered in 5 seconds.  

As a couple of you are in OO, the spacing for the poles would be 11.5 inches apart, in N they would be 5.5 inches apart. In O scale 1:48 they would be 18.35” apart or about 18 and 3/8” .

The system has worked well for me over a number of years and it should for you too!

Cheers from Australia

 

Trevor

[RR_Mel]

Tom

 

I bought a SD9 off eBay that had Ernst gears so I put it back to original just for that reason.  That way one sticker does all.

 

 

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[tstage]

Mel,

I have both switchers and non-switchers on my layout and they all have different stop speeds.  So, that particular labeling method wouldn't well for me.

Tom

[RR_Mel]

I use a small Avery sticker with one end cut to a point labeled in MPH pointing to the throttle position on DC and a label on my handheld for the speed steps on DCC.  The label is for other operators (Grandkids), that’s about the only thing I can remember now days is the speed steps vs speed.

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[nealknows]

Too much paperwork, formulas, stopwatches. I have a better idea. I'm going to call one of my police buddies ask him to bring his hand held radar gun over and we can have some fun getting the speed of the trains. 

[Onewolf]

I have a very simple equation for approximating scale MPH in HO scale:  inches/sec * 5 = scale MPH.

10"/sec = 50 MPH

8"/sec = 40 MPH

etc

etc

[kasskaboose]

Ah, this discussion is all relative.  Get it?! Einstein aside, I am interseted in simple solutions to complex problems. 

Do you keep your locos travelling at a speed reflective of reality or what works for you and your layouts constraints (e.g., elevation, curves, etc.)? 

[Enzoamps]

And then, once we know our train is moving exactly 45 miles per hour, we have to explain why the train left Denver at noon and arrived in Glenwood Springs 2 minutes later.

[richg1998]

Old scchool way. Three foot section of track and a stop watch. This is model railroading, not rocket science. Use math for scale of choice.

My smart phone does the timing and math.

I worked for NASA for fourteen years. I know the difference.

Rich

[doctorwayne]

dstarr

Find a large part of your layout, maybe even a couple of laps around the main line. Measure it with a ruler, and convert real feet into scale miles....

The easiest way to measure your track's length, whether it's straight or curved, is to create a train of a known length - 10' is a good choice, but you can use whatever length works best for your situation.
Put a marker of some sort alongside the track, even with the front of the loco pulling the train, and another alongside the back end of the rear car.  Run the train until the back end of the last car is beside the marker where the loco started.
Now move the marker that was originally beside the loco up to the loco's current position, and repeat the operation until you either arrive back at the marker which originally denoted the back of the train at starting (on a track which affords continuous running) or until you get to the end of the line (as on a point-to-point line).

This is both easier and more accurate than trying to use a tape measure around curves.

Wayne

[Seeker_CNY]

A question for those who use their DCC throttle to indicate scale speed. Does setting your DCC system to run a fast clock affect the speed reading?

[davidmurray]

I did all the math one time:  In HO the number of inches travelled in 5 seconds equals speed in miles per hour.

Dave

 

[mbinsewi]

All of these different formulars and charts !  and methods!  They all have fixed points, and a stop watch involved

I'm not the OP, but I'll stick with the simple formula from the NMRA that Mel posted.

Mike.

EDIT:  That is of course, if I was totally out of mind as to how fast my train was running.  Hasn't happened yet.  

[dstarr]

Divide scale miles traveled by hours. 

Find a large part of your layout, maybe even a couple of laps around the main line.  Measure it with a ruler, and convert real feet into scale miles.  For HO, multiple real feet by 87 to get HO scale feet.  Divide  scale feet by 5280 to obtain scale miles.  The answer will likely be a decimal fraction of a scale mile or two. 

Use a stop watch to measure how long it takes the train to cover the scale mile.  Convert from seconds to hours by dividing measured seconds by 3600 (number of seconds in one hour)  

Divide the measured scale mile by measured time in hours to obtain scale miles per hour.   

  A hand calculator makes it a lot easier. 

[tstage]

I created a printable, at-a-glance table in Excel similar to what Wayne posted and have that up on the wall: (Click table to enlarge)

All I need is the table, a watch or stopwatch, and two fixed points. 

To capture a range from 0 to 60 sMPH, I broke down the measuring distances into three main categories: 3', 1', and 3".  I use the 3' distance for clocking fast moving trains and the 1' & 3" distance for slower moving units.  It's inexpensive, doesn't require electricity, and I can measure it anywhere on the layout. No special device needed.  All I'm looking for is a ballpark idea.

Tom

[mbinsewi]

BATMAN

I just wish the audible report was a sexy babe voice instead of Bob from accounting.

I'm sure they have a CV for that.  Check the manual. 

Mike.

[doctorwayne]

There's a one-page article in the September, 2003 issue of RMC, entitled: "Scale miles-per-hour at a glance".

S.M.P.H. = .6818 X SCALE FACTOR X DISTANCE (in decimal feet) ÷ time

The scale factors are:

O = 48
S  = 64
HO = 87.1
TT = 120
N = 160
Z = 220

The author simplified the formula somewhat, but used a stopwatch and a calculator for timing.

I'm not so fussy, and decided to simplify the formula even more, creating a chart of speeds in increments of 5mph, up to 40mph (the highest allowable speed on my layout) with a rounded-off elapsed time using the second hand on a watch.

While I've not formally created "speed traps", the plan is to use measured lengths of straight, level track, each with signs indicating the "Start" and "End" points.

In HO scale, for example, the speed trap might be only 5' long in one area, and 10' or 15' in others.  Each would have a chart of times and corresponding speeds affixed to the layout's fascia.

For my HO scale layout, travelling through the 5' "trap" in 59 seconds yields a scale speed of 5 mph, in 30 seconds it's 10 smph, 10 seconds 30 smph, and the hogger's hitting the limit when he gets his loco through in 7 seconds.

The main purpose is to allow operators, including myself, to have a sense of what speed is appropriate, especially since most of the mainline does have signed speed limits. 
On the many grades, most trains will have difficulty reaching allowable speeds on uphill trips, and likely the opposite situation when descending those grades, dependent, of course, on the tonnage trailing.

Wayne