Can you scale down weight?

[Grovenor]

 

 

It's the square root of the scale. OK 8 is the square root of 64 which is S scale

Why?

Regards

[Chimer]

Unfortunately you are confusing mass and weight.

 

Volume x density gives you mass. Weight is mass x g. So your block a lead would have a mass of 2.27g here and anywhere else in the universe but it would only have a weight of 0.0223N here on earth. On the moon it would weigh only 0038N but still have a mass of 2.27g.

 

Thanks for reminding me of the difference between weight and mass.  Given that, it follows that, as g is 1 for everything stationary at sea level everywhere on this earth, most railways are fairly close to sea level, and I assume the OP lives on this earth, weight and mass can be considered the same in the context of the original question.

 

There's absolutely no reason for, or sense in, trying to scale weight (or mass!) when modelling railways, but if you really want to, 1/(scale^3) is the target figure. 

[mikesndbs]

No I don't live on this earth but was not going to say 

[RonnieS]

Is scale weight equal to scale performance? On film I have seen a Castle slip to a standstill on 17 loaded milk tanks pus a BG. In official documentation  I think this is about the 500 tons max load. Maybe = to 16 MK1s? A Hornby Castle would slip to a standstill on that.

[Il Grifone]

*pedant mode on*

K=Kelvin (absolute degrees) or kilo, as in Bytes (just checked your profile)

k=kilo for other units

*pedant mode off*

 

Pedant mode on again!

Originally upper case letters (and Greek numbers) were used for metric multiples (deca*, hecto, kilo etc.) and lower case (and Latin) for sub-multiples (deci, centi, milli, micro etc.). with the advent of digital computing Kilo was adopted for 1024 and the lower case for 1000 (just to confuse things**). The confusion remains for mega, giga etc. - this why digital memories always have less bits than they claim - they're sold in decimal (1000s), but read by the computer in binary (1024s).

 

*Should be 'deka' strictly, but since the unit is now obsolete (we are expected to count in thousands) it doesn't really matter.

** Old radios have Kc/s on their tuning scales, now it's kHz.

 

As regards scaling weight, It involves an alternate universe with changes in quantum physics and the speed of light (the maths of which is beyond me), so I'll stick with the simple reduction of the linear dimensions which as previously stated results in the reduction of the real weight by the cube of the scale.

 

Leaving aside the radioactivity of uranium, it is extremely toxic so best avoided. Possible dense alternatives are tungsten, gold and osmium. (All have disadvantages!)

[dhjgreen]

Pedant mode on again!

Originally upper case letters (and Greek numbers) were used for metric multiples (deca*, hecto, kilo etc.) and lower case (and Latin) for sub-multiples (deci, centi, milli, micro etc.). with the advent of digital computing Kilo was adopted for 1024 and the lower case for 1000 (just to confuse things**). The confusion remains for mega, giga etc. - this why digital memories always have less bits than they claim - they're sold in decimal (1000s), but read by the computer in binary (1024s).

 

*Should be 'deka' strictly, but since the unit is now obsolete (we are expected to count in thousands) it doesn't really matter.

** Old radios have Kc/s on their tuning scales, now it's kHz.

 

As regards scaling weight, It involves an alternate universe with changes in quantum physics and the speed of light (the maths of which is beyond me), so I'll stick with the simple reduction of the linear dimensions which as previously stated results in the reduction of the real weight by the cube of the scale.

 

Leaving aside the radioactivity of uranium, it is extremely toxic so best avoided. Possible dense alternatives are tungsten, gold and osmium. (All have disadvantages!)

Yes, for us engineers, the multiples are all thousands so mainly capitals:

kilo (lower case) for us to avoid confusion with Kelvins

Mega

Giga

Terra

for multiples greater than one

 

and lower case

milli

μ (micro)

nano

pico

atto

femto

for multiples less that one

[Il Grifone]

Micro uses either 'mm' (m x m obsolescent) or the Greek letter 'µ' (mu = m). 'µµ' used to be used for pico (now 'p').

 

It's true that centimetre, hectare etc. look destined to stay.

 

Scale performance (haulage) depends on many factors :- loco weight (on driving weights) wheel tyre and rail materials, weight of stock and bearing friction. We don't have the assistance of wheel sanding either.

 

EDIT To replace 'be' that had vanished into cyber space.

[Pacific231G]

Is scale weight equal to scale performance? On film I have seen a Castle slip to a standstill on 17 loaded milk tanks pus a BG. In official documentation  I think this is about the 500 tons max load. Maybe = to 16 MK1s? A Hornby Castle would slip to a standstill on that.

There are so many different factors involved that are scaling in different ways that I doubt if the behaviour of a 1:76 scale model would tell you very much at all about the behaviour of a full size loco or vice versa. I suspect in particular that the rolling resistance of a model is relatively far greater than that of its full size equivalent.

 

Quite apart from that, with the model you're actually looking at the behaviour of a six coupled electric loco which itself would have different slip characteristics from a steam loco.

 

One thing that did strike me when I moved to modelling European H0 was the prevalence of traction tyres even on steam locos- something I'd not then met in either British or American outline- and I've never really understood why. I don't know if it's simply that H0 is a smaller scale than 00 and the UIC loading gauge isn't that much larger than ours so model locos are simply smaller and lighter. The enormous American loading gauge would I suppose tend to cancel out that scale difference so that North American locos in H0 would be much the same size for a particular wheel arrangement as British ones in 00. 

[dhjgreen]

Micro uses either 'mm' (m x m obsolescent) or the Greek letter 'µ' (mu = m). 'µµ' used to used for pico (now 'p').

 

It's true that centimetre, hectare etc. look destined to stay.

 

Scale performance (haulage) depends on many factors :- loco weight (on driving weights) wheel tyre and rail materials, weight of stock and bearing friction. We don't have the assistance of wheel sanding either.

Dratted editor, it had a mu when I posted it!

[Steven B]

If you scale mass, say at 4mm to the foot, then your locos should weigh something around a ton.

How do you work out that value? By my calculations a OO gauge A4 should have a mass of about 10oz.

In OO Scale a model of the Titanic would tip the scales at just over a tenth of a ton.

 

 

 

 

Happy modelling.

 

Steven B.

[newbryford]

How do you work out that value? By my calculations a OO gauge A4 should have a mass of about 10oz.

In OO Scale a model of the Titanic would tip the scales at just over a tenth of a ton.

 

 

 

 

Happy modelling.

 

Steven B.

 

Because he's only calculated it in one dimension - i.e. 1/76.2 and not by volume. 1/(76.2*76.2*76,2)

 

Cheers,

Mick

[CKPR]

There was an exchange of letters on this very topic in the Railway Modeller way way back in 1966-7 in which it was mathematically proved that the whole topic is a chimera (and best left alone)

[Andy Hayter]

Pacific231G

 

Why the use of traction tyres in HO models?

 

I think the ansers can be various, but probably include the following:

 

1.  Smaller "driving wheels" due to the smaller scale - and exaccerbated by manufacturers that insisted that tenderdrive was the way to go (eg Jouef).  Of course this is less relevant to Diesel and electric traction.

2.  Longer trains in part because many modeller had more room (the liveable cellar), in part because of the 13% smaller scale - again perhaps exaccerbated by the use of scale (!) 1:100 length coaches and long wheel base wagons.  US modellers of course took this to the logical extreme with enormously long trains compared with the UK branch line.

3.  The tendancy towards Austrian Swiss (German border) layouts that seemed to demand mountains and thus steep gradients or US crossing the Rockies layouts.

4.  The liking in Europe for the hidden fiddle yard (Schattenbahnhof) under the main baseboards* - which again pushed for steep inclines and helical  drop down/climb up between fiddle yard and viewable layout.    * under rather than behind or at the end or at each end.  I never really understood this since access was never easy.  It did however mean that the viewing area was probably bigger than it would have been if UK type fiddle yards had been more widely adopted - and of course a bigger viewing area allows for longer trains - see point 2.   The helix would frequently be made from small radius set track and so again putting strain on the motive power.   

[Il Grifone]

Further to the esoteric maths involved in scaling weight/mass, I hit on an hypothesis for the phenomenon of bits disappearing when they fall on the flour. Last night a broken off piece of headstock fell on the floor. Despite seeing where it fell, a long search found it about a foot away on a low shelf?????? I then made the mistake of removing a buffer fitted skew (and upside down). This fell straight down and vanished (found this morning where I'd been looking last night!)

 

Anyway, waffle aside, I came to the conclusion that the impact with the floor must create a micro 'worm-hole' into which the errant part disappears. Once inside it spins around in ever decreasing circles in hyperspace (or whatever) until either it emulates the infamous bird and is never seen again or reappears later (days, weeks, years...). This can either be in the same place, which explains why you have looked there several times already without finding it, or elsewhere, which explains "How the hell did it get there!"

 

(An attempt to dismantle a pre-loved Dapol meat van kit where the headstocks had been fitted slightly high stopping the body fitting properly. One came off cleanly, the other in two pieces. I was attempting to fit the second part when the disaster occurred.....)

[petethemole]

I blame the Pixies. In addition to the ones that hide things there are Gravity Pixies.

[Il Grifone]

I thought about calling it 'The Gremlin Hypothesis'

[Pacific231G]

Further to the esoteric maths involved in scaling weight/mass, I hit on an hypothesis for the phenomenon of bits disappearing when they fall on the flour. Last night a broken off piece of headstock fell on the floor. Despite seeing where it fell, a long search found it about a foot away on a low shelf?????? I then made the mistake of removing a buffer fitted skew (and upside down). This fell straight down and vanished (found this morning where I'd been looking last night!)

 

Anyway, waffle aside, I came to the conclusion that the impact with the floor must create a micro 'worm-hole' into which the errant part disappears. Once inside it spins around in ever decreasing circles in hyperspace (or whatever) until either it emulates the infamous bird and is never seen again or reappears later (days, weeks, years...). This can either be in the same place, which explains why you have looked there several times already without finding it, or elsewhere, which explains "How the hell did it get there!"

 

(An attempt to dismantle a pre-loved Dapol meat van kit where the headstocks had been fitted slightly high stopping the body fitting properly. One came off cleanly, the other in two pieces. I was attempting to fit the second part when the disaster occurred.....)

 

I wonder how small a scale you'd need to go down to before getting quantum effects such as flanges ending up the wrong side of rails without passing them ?  Don't laugh. I think some of the work on nano technology involves "railways" and your body is already full of them. I found this quote from a book i have no intention of even looking at  "the self-assembled microtubules that serve as nanoscopic protein railways that enable the transport of “cargo” within the cell using nanoscale protein motors."

 

 

As regards scaling weight, It involves an alternate universe with changes in quantum physics and the speed of light (the maths of which is beyond me), so I'll stick with the simple reduction of the linear dimensions which as previously stated results in the reduction of the real weight by the cube of the scale.

 

Possible dense alternatives are tungsten, gold and osmium. (All have disadvantages!)

 

I'd always thought those Indian Maharajahs with their dining table railways delivering the drinks etc.used gold in them to show off their wealth; clearly though it was just to get better adhesion!!

[dhjgreen]

snip>Further to the esoteric maths involved in scaling weight/mass, I hit on an hypothesis for the phenomenon of bits disappearing when they fall on the flour. Last night a broken off piece of headstock fell on the floor. Despite seeing where it fell, a long search found it about a foot away on a low shelf?????? I then made the mistake of removing a buffer fitted skew (and upside down). This fell straight down and vanished (found this morning where I'd been looking last night!) <snip

 

 

I have found that sometimes the carpet monster can be persuaded to give up its bounty with the aid of one of the new single LED torches. Scan the entire area like a bird of prey quartering a field and the part quite often shines out at you as you pass over it.

[John_Miles]

There is some confusion about scaling in this thread. If you scale length by 1/X then indeed the volume is 1/X cubed, so the mass is multiplied by this to get the actual mass of the model provided the same materials are used as in the real thing. However, this does not scale the mass, it is merely a calculation to work out what the mass of the model will be. I have no experience of scalling applied to mass but I do have experience of it for hydraulics and it involves straying into the area of dimensionless groups and the same techniques will apply here. I suspect those who build ship models at a professional level will know how to deal with scaling mass. My guess is that there is no material dense enough for us to scale mass in a manner that our scale trains have the same dynamic behaviour as the real thing. As I said above, if you are truly scaling everything then our model trains should take hundreds of metres to stiop. They don't because the momentum is too low and this is because the mass is too low.

[raymw]

I don't believe anything can be scaled, it is all a fudge. The best we can do is to get it to look 'right', move 'right' sound 'right'. where 'right' will vary according to a person's belief/understanding, and often that is in direct contrast to the physical reality.

 

For example - a 4mm scale locomotive whistle, you would never be able to hear it. The paint on a scale model car should be shinier than a shiny thing. We tend to exaggerate the defining things of the texture - e.g oversize mortar joints in model brickwork, gaps between planks, wood grain, etc., but it looks OK because it is what we expect to see. We have a general consensus of what is right, but the areas around the edges lead to arguments - e.g. 00/EM/P4 (although other aspects come into play).

 

fwiw, a few years back, I weighed a 7mm Slaters coal wagon, I was surprised to find it was almost the exact 'scale' weight of the full sized item, even though the full sized item was not made of plastic. However, no way did it perform as the full sized item, when rolled along the track. because the model track does not perform as full sized ballasted track, friction, etc., then weight needs to be added, and then you get to the stage that you have nothing capable of pulling more than a few of them,  just another compromise that has to made.

 

Best wishes,

 

Ray

[Peterpiper]

Personally I think your all looking at it the wrong way, by far the easiest way of working this out is borrowing (or stealing) a shrink ray and finding a real locomotive of the type you wish to weight, shrink said loco to scale size, plus side, all materials and components are already there and will be scaled in total, weight loco and return to former owner

[Budgie]

Pedant mode on again!

...

With the advent of digital computing Kilo was adopted for 1024 and the lower case for 1000 (just to confuse things**). The confusion remains for mega, giga etc. - this why digital memories always have less bits than they claim - they're sold in decimal (1000s), but read by the computer in binary (1024s).

This is not strictly correct. Things have changed.

 

1024 bytes is a kibibyte, abbreviated KiB.

Similarly there are multiples abbreviated as MiB, GiB, TiB, etc., where the full name is formed of the first two letters of the normal Greek prefix, followed by "bi" for binary, then followed by the unit. So TiB stands for tebibyte, etc.

 

More information is available on Wikipedia

[Steven B]

There is some confusion about scaling in this thread. If you scale length by 1/X then indeed the volume is 1/X cubed, so the mass is multiplied by this to get the actual mass of the model provided the same materials are used as in the real thing. However, this does not scale the mass, it is merely a calculation to work out what the mass of the model will be. I have no experience of scalling applied to mass but I do have experience of it for hydraulics and it involves straying into the area of dimensionless groups and the same techniques will apply here. I suspect those who build ship models at a professional level will know how to deal with scaling mass. My guess is that there is no material dense enough for us to scale mass in a manner that our scale trains have the same dynamic behaviour as the real thing. As I said above, if you are truly scaling everything then our model trains should take hundreds of metres to stiop. They don't because the momentum is too low and this is because the mass is too low.

 

Scaling by 1/x cubed will scale the mass. However, what we're stuck with is 1:1 scale gravity and friction. You'd need a scale earth to run your trains on, and lubricants etc with scaled consistency to make scale models run as the real thing does. Until then we'll have to carry on with our bodges.

 

What we're trying to achieve has been done for years in the aerospace and automotive industry; Wind-tunnels are run at higher speeds or higher pressures to allow for the difference in scale.

 

What we really need is to run our trains in a pressure/vacuum vessel with reduced gravity!

 

Happy modelling.

 

Steven B.

 

[meil]

Why?

Regards

The time period (T) of a simple pendulum is 2*PI*(L/g)^0.5

 

for a pendulum 64 metres long T = 2*PI*(64/9.81)^0.5 = 16sec

 

for a pendulum 1m long (i.e. an S scale representation of the full size pendulum) the period T = 2sec

 

i.e. 8 times quicker and the sq root of 64 is 8

[Il Grifone]

This is not strictly correct. Things have changed.

 

1024 bytes is a kibibyte, abbreviated KiB.

Similarly there are multiples abbreviated as MiB, GiB, TiB, etc., where the full name is formed of the first two letters of the normal Greek prefix, followed by "bi" for binary, then followed by the unit. So TiB stands for tebibyte, etc.

 

More information is available on Wikipedia

 

I'm obviously behind the times on this, but the last flash drives I bought were sold as 16GB which of course is 16,000,000,000.