Scale speed

"Piemanlarger" wrote

HO is approx 7/8th of OO so to increase HO speed to OO increase by 1/7th. At least that's what my ancient mathematics seems to think would be correct.

Who's going to flame that suggestion? ;-)

John.

If you do an H0 mile in a minute that woyuld be 60mph in H0 scale but its only 7/8 of a 00 mile in a minute, or 52.5 mph in 00.

Hence to get 60mph in 00 you need to read 60 x 8/7 = 68 approx. on your H0 speedometer.

Which I think is what John meant. Keith

John,

Well if you take H0 as 3.5mm/ft and 00 as 4mm/ft, H0 is exactly 7/8th :-)

Jim

Here is the reasoning:

OO scale (4mm/ft) is a ratio of 1:76.2 A 5,280ft mile in OO scale is 69.29ft, or 831.5in.

1 mph = 1.609 kph To convert KPH to MPH, multiply KPH by 1.609

1kph = .621 mph To convert MPH to KPH, multiply MPH by .621

Here is how to use it:

Example:

60 mph is 88ft/sec. In OO scale that is equivalent to 1.155' or 13.9in/sec

To determine how many feet per second is related to any speed you must know the distance traveled in a measured time.

One hour is 3600 seconds (60 sec = 1 min. times 60 min = 1 hr.) 60 X 60 = 3600

80 miles is 422,400 ft. divided by 3600 = 117.333 ft/sec

117.333 ft divided by 76.2 = 1.54 ft/sec or 18.48 in/sec. Thus 18.48 inches/second is the OO scale equivalent speed to 80 prototype MPH

Simply divide the speed expressed in MPH by 3600 and you get miles/sec. Multiply that number by 5,280 and you get feet/sec. Divide that number by the scale ratio, in this case 76.2, and you get the proper ft/sec. for scale speed Multiply that number by 12 and you get scale inches/sec.

125 mph / 3600 = .034722 mi/sec.

.034722 X 5,280 = 183.333 ft/sec

183.333 / 76.2 = 2.406 ft/sec.

2.406 ft X 12 = 28.87 in/sec

Thus, 28.87 in/sec is the OO scale equivalent of 125 mph.

HTH

The Fleischmann 'tachometer' is an everyday bicycle speedometer/computer. As such it will have provision for adjusting the wheel size so that the normal 'tachometer' can be retro-fitted to any bicycle with any normal sized wheel. All you need to know is the wagon wheel diameter in your scale and the sequence in which to push the buttons to input that wheel-size. It should also have a km/hr/mph setting, but if not then you need a

1.609x larger wheel setting to get it to read mph directly.

Good luck, Greg.P.

Gawd! Did you allow for Coriolis Effect and Heisenberg's Uncertainty Principle for accuracy?? :-)

Steve Newcastle NSW Aust

You appear to have ignored the delayed neutron release interval which is so essential to correctly regulated HO operations.

Peter A

ps Non of my gear can tell the difference!

and then when you get it running at the right speed, it "looks" wrong, and you have to slow it down a tad.....

And it would help if you got it right. By your reasoning, 10 kph is 16 mph. Errr, no - that's the wrong way round.

To convert kph to mph, *divide* the kph figure by 1.609.

To convert mph to kph, *multiply* the mph figure by 1.609.

16 kpm = 10 mph

The absence of any further comment should not be taken as confirming the rest of your "reasoning". I stopped reading after such a fundamental error in your basic arithmetic.

Steve

sounds good. Multiply by 1.14 (which is, coincidentaly, how you get mph from knots - spooky)

Yes, of course, you're absolutely right. So I read the rest and found it to be completely irrelevant to the original request. Which already specifies that scale speeds can be measured. The problem is one of scale conversion not one of either measuring speeds or of speed unit conversion.

So with V=D/T, we can write

V[00]=D[00]/T and

V[H0]=D[H0]/T

But D[00]=7/8 D[H0]

So substituting, dividing and then cancelling the common terms we get

V[00]/V[H0]=7/8 and so

V[00] =7/8 * V[H0]

For V[00] = 80mph then V[H0] = 80 * 8/7

And guess what? The first answer "HO is approx 7/8th of OO so to increase HO speed to OO increase by 1/7th." is perfectly correct and simple to understand.

Whoops, seems like you were wrong on every count too. As in any exam, it pays to read and *understand* the question before giving an answer.

Thank you and goodbye - you lose.

Steve

unless you're a Marklin fan, where you have to double the speed!

Do you have the conversion factor to get knots from string?

;-)

depends on the knot :o)

actually, knots (nautical miles per hour) was actually real knots on a rope - can't remember how far appart they were (18 feet or sunnik) and on the end of the rope was a triangular board a foot on each side called a "chip log". You drop it over the back and it drags in the water pulling out the rope... the number of knots passing through your hand in a minute was your speed.True and totally irrelavant, but it was the nearest smart answer I could give to your smart question :o)

Well the kilometer was originally defined by the size of the same earth as the one defining the nautical mile. Might be more spooky if there was no equivalence :))

Ken.

I'm an ex-nautical man. :-)

LOL :-) Fortunately, trains have sufficient mass such that we can know both their position AND their speed and direction, all at the same time. They would have to be a mite smaller for the UP to come into effect.

There is a simpler way of doing it, but sometimes simpler is not always better. I would rather show the whole process than to simply dispense some "magic number" by which you multiply to get the correct speed for OO scale. If you know, or can see the process involved in an expanded way, you can determine how to use it for any scale, not just OO.