How does one calculate the equivalent speed of a 1:20.3 model to the prototypical speed? It is simply multiplying the length of model track by the scale, or must the time be also “tweaked” to calculate the model’s travel over a know distance of say 100 feet.
Inquiring minds want to know.
In standard gauge trains, the 40 ft car is so common, I just remember 40ft/second is 27 1/4 MPH.
How long (scale) are your cars?
Pull out your handy calculator. Multiply the length of the cars (or some common car) by 3600, then divide by 5280. Now, if you see 1 car pass per second, that’s how fast you’re going. If 1 car passes in 2 seconds, you’re going half that fast. If 2 cars pass in a second, you’re going twice that fast.
This works in any scale, and with any object that’s a fairly constant size.
With one figure in mind, I can estimate the speed of my train any time I want. It just happens that 25 to 30 MPH is an appropriate speed for Madam Mallet.
So how long fast is a 1:20.3 locomotive traveling 100 feet in 90 seconds traveling in prototype MPH? I’m a high school dropout.
Okay David…I’ll give it a try.
Scale factor of 20.3 X 60’/min (90’/1 1/2 min) X 60 min = 73,080 ft/ hr divided by 5280 ft/ mile = about 15.22 mph
I think???
Randy
David, 100 feet in 1:1 is 2,030 ft in 1:20.3. 2,030 feet in 90 seconds is 22.56 feet per second. This is 81,216 feet per hour. Or, to be closer to what you want, it’s 15.4 mph. Rather than to this calculation all the time, you might want to do what I did and use a bicycle speedometer to get the scale speed. It also acts as an odometer. Very handy for measuring how much track you really have. See http://www.largescalecentral.com/forums/topic/7422/search/view/post_id/44365
Or ya can do it Bruce’s way too.
Randy
Oh, no. Here we go again.
Let me preface this by saying Bruce has it right as far as I’m concerned. Whatever scale you are, you’re going around the sun at the same speed as anyone else… it’s the distance you cover while you’re doing it that determines speed.
In a moment, depending on what time it is in Japan, another member will be along to tell you you have to scale time as well, and that 45/3 is not 15. And, then it will be well and truly on, until Bob or someone posts the offical LSC “Shut Up Duck.” Laugh, try to keep up, sigh, roll your eyes, take sides, and tell us we’re all completely full of it … but fasten your seat belts; here it comes. Beyond here, there be dragons.
Bruce and Randy wer with in .2 of each other. Thats great.
Now my dumb question. Why does scale speed matter? No realy. I just run my trains at a speed my eye (me) seems to like or that please me for what I’m doing at the time.
I think that besides the way it looks to our eyes its interesting to have something to compare to.
Sure, its the best to go like it gives the best looks.
for calculating:
it quite easy in 1:20,3. Let alone the 0.3.
so, while the real RR makes 20, the model makes 1. What?–never mind! inches, miles, kilometers, meters…elbows…
So, while we reduce the three dimensions of volume, we DONT reduce the time. Therefore the speed of a modelRR is reduced by the scale. JUST by the scale, because velocity follows just one dimension: length.
so, look at it like u will:
u can go 1 yard per second “real” what makes 20 "little"yards/second in scale.
or
when your garden RR goes at 40mph(scaled), those are REALLY only about 2 miles per hour (fast walk for you)
or
your garden RR does 100 feet in 4 seconds, that gives 25 feet per second, upscaled arround 500 feet per second. that would be 340 mph, the fastest train in the world!
Frank
Thanks Bruce and Randy. Where I was getting all befuddled was reading about guys that run ‘operating sessions’ and use a ‘fast clock’ to compress the session. What I now assume the reason is is to compensate for the shortened distances between stops, towns, etc.
(http://www.lscdata.com/users/lastmanout/_forumfiles/handface.gif)
David Hill said:
Thanks Bruce and Randy. Where I was getting all befuddled was reading about guys that run ‘operating sessions’ and use a ‘fast clock’ to compress the session. What I now assume the reason is is to compensate for the shortened distances between stops, towns, etc.(http://www.lscdata.com/users/lastmanout/_forumfiles/handface.gif)
You’re assumption is correct. Since train layouts are compressed versions of the real thing some do use a “fast clock” to more closely simulate a real timetable. Others just use “real time” and compress the operating session in accordingly. For example, the distance between 2 points in reality may be 10 miles and take 30 minutes to get there. On a layout the distance will be compressed so the time would take only about 2 minutes. A “fast clock” would more closely simulate the 30 minute time frame to cover the distance.
I’m not aware of anyone in large scale that is using a fast clock. There could be a bunch of folks doing it, but none of the railroads that I’ve run on use it.
You typically use a fast clock to run trains to a timetable.
I have scheduled trains on the J&B, but typically run one to completion, then run the other. I have run both at once and I set up a meet ahead of time via Form 19.
Others use a dispatcher to control the trains.
I do like slow speeds and typically run my trains at about 15 mph. The speedometer car was helpful in letting me know how fast I was going.
Whit the era I am modeling, the trains typically ran 12 20 MPH. They were capable of higher speeds but the tracks weren’t.
I like the speedo-car! Thanks again.
“But wasn’t that mighty slow?”
“Compared to what?”
If a “fast” clock runs a little slow, is it still a “fast” clock???
Andy Clarke said:
If a "fast" clock runs a little slow, is it still a "fast" clock?????
I just remember that 22 feet / second is 15 mph. Both my steel and wood hoppers are 23 feet, so they serve as an easy gauge. If they take less than 1 second to pass a plant, then it’s time to back off the throttle a bit.
I tried fast clocks on my old HO railroad; they never did much for me. I figured if I wanted to operate on a timetable, then I could use real time just as easily. The primary appeal of fast clocks are twofold: First, they “shorten” the distance between yards and sidings on a model railroad by making it seem like it takes 30 minutes when the two locations are in reality separated by 20’ of track. Second, it simulates all the “down time” when switching that occurs while waiting for brakes to charge up, inspecting the train, etc–things we rarely do in model railroading because the train is sitting still. When trains are on the tracks, we want to see them moving! 
Later,
K
“Time is an illusion. Lunch time, doubly so.”
On the back of the KVRwy transmitters there is a chart -
I use a 1/24th 10 ft Speed Scale - Travel Time per 10 ft.
2 seconds = 82 mph
4 seconds = 41 mph
8 seconds = 21 mph
16 seconds = 10 mph
32 seconds = 5 mph
I have a 12 foot bridge in the back yard. Using that as the distance, you can do the “one thousand one, one thousand two” routine and come up with how many seconds across the bridge. Then from that you can scale out the speed and come up with time traveled and how fast you are going at a particular scale. It works, but after awhile you get used to what you think the proper spped should be. We keep it slow like the steam tourist lines of the EBT, Durango and Silvertone or Cumbres and Toltec. However, kids of all ages like NASCAR.
Zoom, Zoom, Zoom…
