Scale speed

Right, a Fleishmann tachometer thing has come into my possession for
measuring scale speeds, average, max, trip time, trip distance etc etc.
I am really only interested in setting an accurate max scale speed for
different locos, i.e. 80 mph
Trouble is
a/ its in KMh. ok, i can convert kmh into mph
These being some of my interestd speeds
27mph = 43 kmh
60mph = 96 kmh
75mph = 120 kmh
80mph = 128 kmh
85mph = 136 kmh
90mph = 144 kmh
but
b/ its also calibrated for HO, not 00.
So, any bright spark know to convert 128 kmh = 80 mph in ho to 00? What
should my ho scale speed in kmh be reading for a true 00, 80 mph?
Thanks?
Simon

Reply to
Piemanlarger
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"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.
Reply to
John Turner
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
Reply to
Keith
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
Reply to
66class
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.
Reply to
Greg Procter
Gawd! Did you allow for Coriolis Effect and Heisenberg's Uncertainty Principle for accuracy?? :-)
Steve Newcastle NSW Aust
Reply to
Steve Magee
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!
Reply to
peter abraham
and then when you get it running at the right speed, it "looks" wrong, and you have to slow it down a tad.....
Reply to
scoot
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
Reply to
Steve Hancock
Ok so he made a error, try reading the rest...it makes more sense than other explanations. BTW Bet your glad they didnt throw out your exam papers on finding the first error - resigning you to the intelectual scrap heap. Snooty old Tosser!!!
Reply to
Nick Beard
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
Reply to
Steve Hancock
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)
Reply to
unclewobbly
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.
Reply to
Ken Parkes
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.
Reply to
66class

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