Train speed

[Anonymous]

I'm not sure how to word the question, but does anyone know the formula for determining the speed of an HO scale train compared to the prototype.
I thought I saw it once in MR, But I can't find it anywhere now [:(!]

[Anonymous]

Let me see now

v = d/t
where v is velocity
d is distance
t is time

So if I'm correct in my calculations speed = scale distance in miles divided by time in hours

My only issue with this is whether or not time should be scaled, any Einstein's out there? Or is this a relative question?

[Anonymous]

I just happen to have a formula I calculated, using true HO scale proportion (3.5 mm = 1 scale foot, not exactly 1:87). Time does not scale, it is a constant.

s=(381d)/(77t)

where
s is scale miles per hour
d is distance traveled in real inches
t is time in seconds

[Anonymous]

Time is constant ..only the distance is scaled.

You'll need to double check my math but based on

1:87 scale

1 mile = 5280 feet
1 hour = 3600 seconds

back to finish later

DT

[Anonymous]

Thanx for the info !!!!
Now, if I can only get rid of the headache I've got from trying to figure that out !!!!![swg][D)]

[ndbprr]

5280'/87=60.69' so if a train going 60 mph in real life would cover one mile in one minute. to do the same thing an HO train would have to cover 60.69 ACTUAL feet in a minute to equal 60 mph or slightly more than one foot per second. 30 mph would be two seconds.

[Anonymous]

in the Railwire link i have someone did a scale speed chart in HO an N

[Jetrock]

Time is constant only if you're using 1:1 time clocks for your railroad--plenty of model railroaders use "fast clock" operation to mentally expand the size of their layouts.

ndbprr's post provides a good easy-to-remember approximate rule of thumb, though--in HO, if your locomotive is traveling 1 foot per second it is running at about 60 miles per hour. In N, 1 foot per second would be about 120 miles per hour, give or take--you can figure other speeds from there. This is actually really, really useful for me--my layout has a 25 MPH speed limit (due to the danger in crossing residential streets and the sharp interurban curves involved) and my mainline is currently a bit over six feet long--so my locomotives should run from one end to the other in no less than about 15 seconds! Now I'll have to go out to the layout and test out this theory...

[Eriediamond]

Whew, boy what a workout ya'll have given this old cob webbed brain of mine. Been trying to figure all thos feet per second into MPH. Gave up on it. I don't have any speed cops on my layout so I use the MPH stamped on my power packs. Saves a lot of wear and tear on the ole gray matter. [banghead][banghead][banghead][%-)][%-)][%-)][(-D][(-D][(-D][zzz][zzz][zzz]

[ndbprr]

I have a difficult time understanding why so many people have problems with math but here goes HO
1 foot per second = 60mph
1' in 1.2 seconds = 50 mph ( Its easier to go 5' in 6 sec though)
1' in 1.33 seconds = 40 mph (3' in 4 seconds)
1' in 2 seconds = 30 mph
1' in 3 seconds = 20mph
1' in 4 seconds = 15 mph

N gauge just double the timesfor ball park times
60mph = 1' in 2 seconds
50 = 1' in 2.4 seconds
40 = 1' in 2.66 seconds
30 = 1' in 4 seocnds
20 = 1' in 6 seconds
15 = 1' in 8 seconds

[Eriediamond]

gotha there ndbprr.[:D][:D] How fast is that in actual MPH. Is it one, two or what?? I understand the feet per second thing but [banghead] trying to figure out if I want to simulate a 70 MPH passenger train, how fast does the HO scale run in MPH. Yeah I know, my fore head is getting sore!![(-D][(-D][%-)][%-)][%-)]

[Roadtrp]

"I have a difficult time understanding why so many people have problems with math but here goes "

I have a difficult time understanding why so many people have problems with tact... [;)]

To be exact -- for 'N' scale 33" in 5 seconds = 60 MPH.

[:)]

[ndbprr]

QUOTE: Originally posted by Eriediamond

gotha there ndbprr.[:D][:D] How fast is that in actual MPH. Is it one, two or what?? I understand the feet per second thing but [banghead] trying to figure out if I want to simulate a 70 MPH passenger train, how fast does the HO scale run in MPH. Yeah I know, my fore head is getting sore!![(-D][(-D][%-)][%-)][%-)]

OK If one foot in one second is sixty mph then the distance needed to be covered in one second increases or the time to cover one foot decreases. It can be done either way so to increase the distance it is 70/60 times 1' or 7/6 of one foot or 14". To do it the other way you need to reverse the numerator and denominator or 60/70 times 1 second or 6/7 of a second which is .85 seconds to cover one foot. Personally it is easier to measure 14" than fractions of a second.

[Eriediamond]

ARGGGHHH [banghead][banghead][banghead][banghead] I got the part about 14" per second equaling 70 MPH. Let me puy this another way. If my HO scale train is traveling an actual 2 MPH, how fast would the full scale train be going in MPH???? Does this make more sense?[%-)][%-)]

[Eriediamond]

Maybe the light bulb just came on here. If for an example a real train is traveling 70 MPH and I divide that by 87 then my HO train should travel .80 MPH to simulate this. Is this right??? Seems too simple for some reason![:)]

[Anonymous]

70 miles times 1/87th = 0.80 miles
per hour.

As was stated earlier, time is a constant, so the only scaled dimension is the miles, or the length. So yes, it really is just that simple. Now, if you want to run a fast clock and scale the time as well, then you'll end up with rocket-fast locos; usually a fast clock is anywhere from 2 to 6 times as fast as normal. The entire reason for using a fast clock, though, is to make or short runs seem longer, because we don't have a full 50 scale miles of mainline to traverse between towns. So, scaling the time in a mph calculation undermines the whole purpose of the fast clock.

Just multiply the target mph times the scale ratio, it's easy.

[Eriediamond]

Thanks Avondaleguy, Glad I got that figuered out. Now for the fast clock thing, I ain't gett'in in to that, heck time goes to fast as it is!!!!![(-D][(-D][(-D]

[ndbprr]

well there is another way of saying it too and that is if your train is doing a scale 60 mph it is covering a real 60.69' per minute. 60.69' times 60 minutes = an actual distance of 3641.4' traveled in an hour. SInce one mile = 5280' it is actually moving at 3641.4/5280 miles per hour or a speed of .6895 miles per hour or for all practical purposes 7/10 of a mile per hour.