Just wondering how fast my A line train was running, is this the right math?
A line is 1.17 sale mile, took 3.06 minutes to cover the line. I dived 60 minutes by the 3.06 minutes = 19.6 x 1.17 scale mile = 22.932 sMHP. Seems right, what do you folks think?
Cuda Ken
I hate Rust
Yep, that works.
Enjoy
Paul
Your math is pretty close - if the distance is correct (70.925 actual feet), and the time is equally correct, it comes out to 22.94 smph. The math formula is:
(((D/T) x 3600) / 5280) x Sc = Scale Speed in MPH
Where:
D= Distance in actual feet
T = Time in seconds
Sc = Scale factor (HO=87.1, N=160, O=48, S=64)
Works out well for a spreadsheet - makes a handy chart you can use easily.
---
Gary M. Collins gmcrailgNOSPAM@gmail.com
===================================
"Common Sense, Ain't!" -- G. M. Collins
http://fhn.site90.net
Seems slow to me. - Especially from a former Dragster.
TAKE a 12" ruler and lay alongside a section of straight track, anywhere.
With a stopwatch: 1 second = 60MPH in HO; 2 seconds = 30MPH; and 1/2 second = 120 MPH.
(5,280' divided by 87.1 = 60.61' in HO. Divided by 60 seconds = 1.01 feet per second).
CLOSE ENOUGH.
There is an electronic timer available for about $60 that will record your speed each tine around, with more accuracy.
I agree with Don. I have several one foot spots "marked off" on my mainline. Anytime I want to estimate speed, I time the train passing one of the spots with a stopwatch. The general numbers Don mentioned are usually good enough. I have these check points on the level, upgrade and down grade. Checking sevral will give you a good average. Also, most #6 switches are 12 inches long so you can use those to check speed as well. I've thought about the fancy speed indicators, maybe when I have 60 or so "spare" bucks.
Tilden
Tilden wrote:I agree with Don. I have several one foot spots "marked off" on my mainline. Anytime I want to estimate speed, I time the train passing one of the spots with a stopwatch...Checking sevral will give you a good average. Also, most #6 switches are 12 inches long so you can use those to check speed as well. Tilden
I agree with Don. I have several one foot spots "marked off" on my mainline. Anytime I want to estimate speed, I time the train passing one of the spots with a stopwatch...Checking sevral will give you a good average. Also, most #6 switches are 12 inches long so you can use those to check speed as well.
Simplicity is a wonderful thing...and cheaper!
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Be nice if you could use one scale mile rather than 1.17 scale miles, then the math becomes easier.
1 mile in 1 minutes = 60 MPH
1 mile in 2 minutes = 30 MPH
1 mile in 4 minutes = 15 MPH
Once you have those numbers, it's not too hard to figure the intervening times...like 90 seconds is half way between one min. and two minutes, so the speed must be half way between 60 MPH and 30 MPH - 45 MPH.
HI there,
I have written this up on my website but effectively if you count the number of inches your train travels in 5 seconds, that is as near as dammit to the SMPH. THis ties in to the equations given earlier 12"in a second = 60 in 2 secs = 30smph etc. There is a fuller explanation on my website including calculations for other scales!
Regards
Trevor
website www.xdford.digitalzones.com
Gandy Dancer wrote:Of course all this assumes you are not using a fast clock. There is one layout I operate on that uses a 12:1 fast clock. I always feel like my trains are a flying. I really don't like it. Another layout in the operating rotation has a 8:1 clock, it is much more reasonible especially since the towns are so close together.
Really, a fast clock doesn't alter scale miles per hour. A train going 30 scale MPH is still running two miles every minute, even if the fast time clock at 12:1 ratio shows it as taking 4 minutes (or 15 smph). I think the key purpose of the fast clock is that on our layouts, towns are much closer together than in real life, and operations like preparing an engine in a servicing area, making up a train, switching industries, etc. all take less time than they do on the prototype. The fast clock is meant to compensate for that.
Here's a method for your steam power that is quite accurate: First determine the diameter of your drive wheels. Your Big Boy, for example has 68" drivers. Multiply that by 3.14. which is pi, (3.14 x 68 = 213.52) and you have the distance traveled in inches per revolution of the drivers. Next count the driver revolutions in a ten second interval - or longer for greater accuracy. Let us say 20 revs in 10 sec. Multiply your inches per rev by the 20 revs in 10 seconds (213.52 x 20 = 4270.4) Multiply again by 6 (4270.4 x 6 = 25622.4) to get inches traveled per minute. Multiply again by 60 (25622.4 x 60 = 1537344) and you have inches per hour. Then convert to feet by dividing by 12 (=128112) Convert to MPH by dividing one last time by 5280 and the result for a Big Boy making 20 revs in 10 seconds is 24.26 mph.
The key to this method is counting revs accurately. The best method is to blink your eyes rapidly while watching the spinning drivers. This will appear as a strobe effect, as you will catch the rods in the same place on each revolution, thus facilitating an easy and accurate count. For real fun, try this at ever higher speeds.
Liberal amounts of alcohol seem to help the process, too.
From my post on the Layout and Layout building forum, here's the easiest way I knoow of to calculate scale speed.
Something I learned from an employee timetable of the Staten Island Rapid Transit line, which did switching for the B&O on Staten Island in NYC. A 40' car will pass a fixed point in 1 second at 28 mph, a 50' car at 35mph. So your 40' cars need to take longer than 7 sec. to pass a fixed spot for safe switching. That ought to stretch out the ol' operating sessions. Ken