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+--- Thread: Train speed (/showthread.php?tid=416)
Train speed - railroader9731 - 01-02-2009
Ok heres one for you guys and gals, how do you find out what scale speed your loco is doing?
Re: Train speed - ngauger - 01-02-2009
By using the Scale Train Speed Calculator.....
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Re: Train speed - doctorwayne - 01-02-2009
There was a short article on this in the September 2003 issue of RMC magazine. The basic formula for scale miles per hour (S.M.P.H.) is:
S.M.P.H.= .6818 x Scale Factor x Distance (in decimal feet) / Time
The number .6818 is a constant
The Scale Factor is dependent on the scale, and is as follows O = 48, S + 64, HO = 87.1, N = 160, Z = 220
The decimal distance means 6" = .5', 9" = .75', etc.
The time is measured in seconds
So, for example, if an N scale loco travels two feet in 4.32 seconds, the formula gives us .6818 x 160 x 2 divided by 4.32 or 218.176 / 4.32 = 50.5 S.M.P.H.
Because this method is rather cumbersome and requires a stopwatch, the author, Ron LaFever, constructed a table in 5 s.m.p.h. increments. From the example above, 218.176 / s.m.p.h. = seconds, so 218.176 / 5 s.m.p.h. = 43.64 seconds. From this it was easy to calculate that a loco at 10 s.m.p.h. would take half the time to cover the 2' distance, etc., etc. He then marked a tie on his layout with a dot of paint, and another 2' away with a second dot. With the table posted on the layout facia, and a wristwatch with a second hand, an operator can get a good sense of what the actual train speed would be.
He also did a table for his HO scale switching layout, using a 1' long measuring area, due to the limited space and slow speeds. His table shows that it takes 59.39 seconds for an HO scale loco to cover the 1' distance at a speed of 1 s.m.p.h., and, at 5 s.m.p.h., the elapsed time was 11.88 seconds.
He notes two general rules of thumb: the slower the speed being measured, the shorter the distance should be, and the faster the speed, the longer the distance.
I already have speed limit signs on my layout, and plan to incorporated several speed "traps", using signs to denote the "START" and "END" points. Most areas of my layout are 30 s.m.p.h. or less, due to curves and/or grades. You can make the measuring area on straight track or curved track (for curved track, assemble enough cars together to equal the desired length, then run them to the curve you wish to use). Most will find that your trains are running faster than you thought, and I think a couple of these speed zones will get you used to running at more prototypical speeds. For most of us, that will increase the running time between destinations, which will contribute to making your layout feel larger. You'll probably become accustomed to more prototypical speeds, too, and won't need to do frequent speed checks. However, they'll still be useful when you have visiting operators - you have to ensure they obey the posted speed limits.
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Of course, Mikey's link is even easier.
Wayne
Re: Train speed - eightyeightfan1 - 01-02-2009
OK..You lost me at "There was a short......"
Re: Train speed - railroader9731 - 01-02-2009
Thanks guys. Love the web site you provided ngauger and as always the dr. has information and pics to back it up Ill be sure to look em over later.
Re: Train speed - Steamtrains - 01-02-2009
Doc....That is a good method, although, I'm sure, somewhat cumbersome...Will give it a try...Do you know how the "constant factor" was arrived at..?? Is this something like a "gravitational" constant for model trains..???
Re: Train speed - Sumpter250 - 01-02-2009
speed, is really a constant, so if 44 feet/second=30MPH, then 44 scale feet/second = 30 scale MPH...or, 1 steam era boxcar/second = 30 MPH.....close enough for government work. Oh, and I do not allow anyone with a radar gun, anywhere near my layout!
Quote:Do you know how the "constant factor" was arrived at..??The "constant" converts feet/second, into miles/hour...or Scale feet per second, into Scale miles per hour. 88 feet/second is 60 MPH.
{{ 60 X 5280=316800 feet per hour.../60 (minutes)=5280 feet per minute (hmmm mile a minute)/60(seconds)=88 feet per second}}
88 X .6818 =59.9984 (.0016 MPH (8.448 fps) short of 60mph)
*****the "constant" is actually .681818181818181818181818181818181818****
You can use a constant because speed is linear 44FPS=30MPH, 88FPS=60MPH, 176 FPS=120MPH. What ever you do to FPS, also happens to MPH.
Two steam era boxcars = 80 feet.....Two steam era boxcars / second =80 SFPS =60 SMPH..close enough for government work.
Re: Train speed - railroader9731 - 01-04-2009
Jeez what i thought was around 25-30 mph turned out to be 10-15 mph :o Thanks again for all the info guys, now off to the layout to do some speed zones.
Re: Train speed - Brakie - 01-04-2009
I run around 35-40 scale mph..
At the Bucyrus club It takes about 3 mintues around the front layout due to the stiff grades..