Title says it all.Thanks!
Last time I looked, it was 1 lb.
If you’re trying to figure out what the equivalent prototype weight is, multiply 87x87x87.
658,503 lbs. IOW, if your HO scale Mikado (less tender) weighs 1 lb, it’s the equivalent of a Mikado with a real obesity problem.
Andre
A. 1 pound (gravity is a constant regardless of scale)
B. 658,503 pounds (87 cubed)
C. .0000015 pounds/HO cu ft (one pound distrbuted over 87 cubed the volume of space)
Or, another way:
1 HO pound = 1/87 x 1/87 x 1/87 real pound
1 HO pound = 1/658503 real pound
1 HO pound = .0000015 real pound (decimal conversion)
1 HO pound = .000024 real ounce
And so an HO car lettered with a 100,000 pound capacity should be able to carry 2.4 ounces.
Ed
In general it’s a meaningless number, for all practical purposes. Models are made of different materials than the real thing, with hugely out of scale dimensions (the ones you can’t see, generally). I can’t think of a practical use for even figuring it out.
Although I’m a disagreeable sort, I think I almost have to agree with this. I don’t think you can scale down weight, at least not by itself. I think, however, that you can scale down how much something weighs. In the posts above, the calculation to scale down weight involved dividing weight by 1/87 X 1/87 X 1/87. If I remember some math course from long ago and apply (I think they were called) dimensions to the values, we end up with pounds/cubic feet.
So if we take something that weighs 1 pound per cubic foot and then divide that by 1/87 X1/87 X 1/87 we’ll end up with the 0.000024 pound number mentioned above since the cubic foot dimensions cancel out.
Therefore, if you were loading your tank car with water, you’d divide the weight of a cubic foot of water by 1/87 (cubed) and arrive at a weight of 0.000094 pounds per scale cubic foot. Then you’d have to multiply this value by the scale capacity of the tank car (20,000 gallons?) to arrive at what the theoretical scale load of the car should be. I think in this case the answer is 1.88 pounds.
You can do the same calculation for a gondola with a steel load if you start with a real weight of approximately 489 pounds per cubic foot.
Obviously those folks who think the NMRA weight recommendations are too heavy will never agree to these new values.
But then again, I suppose someone smarter than I could scale down gravity to HO and see how the numbers come out.
You CAN scale down weight. WHat you can’t scale down are things like friction and gravity. Slippery plastic axles in slippery plastic sideframes rolls differently than a steel axle in roller bearings or in brass lubricated with waste. Nickle-silver wheels roll differently on nickel silver rail than steel wheels on steel rails.
–Randy
I think it’s a good thing our trains aren’t weighted to scale, knowing those calculations. My Keystone 20-Ton Shay would only weigh 0.97oz, which would make it practically useless.[:O] And an F unit would only be about 5.5oz.
Maxman’s logic is correct. But one cubic foot of space equals 1728 cubic inches. One gallon is 231 cubic inches. The weight of the water in your 20,000 gallon HO tank car would be approximately 7.48 times less than the 1.88 pounds stated in his email. About 4 ounces.
Lessee. 1 gallon of water weighs 8.33 lbs. 20K gallons would weigh 166,600 lbs. Given that the equivalent cubic HO volume is 1/658503 of the volume required for 20,000 gallons, then the ratio is 166600/658503 which equals .253 rounded. IOW, the weight would be a little over 4 oz (1/4 lb).
Yup. You’re right.
Now that we’ve got that solved, maybe we should discuss whether or not a 1:87 universe is possible, what the speed of light would be within such a universe and whether or not it was created with a 1/87 Big Bang.
Oh yeah and what the temperature of 1:87 space is.
Andre
Andre
Much more interesting than all the scale/weight theory (IMHO) is what a really obese Mikado would look like…
[:P]
All I know is Max Planck would have an HO field day… or maybe an “h” "e" field day… [:P]
Technically no, you can’t because you can’t scale down density. Theoretically HO scale steel would be waaaaaay denser than real steel because the HO sized molecules and atoms would be closer together. So in teh space that a real atom of iron occupies there would be 658,000 HO scale atoms of iron. But they aren’t because the atoms stay real sized. So weight does not truly scale.
Why would the weight be 1/87 cubed? Why not 1/87?
The 1/87 cubed is a volume measurement.
Oh, the speed of light is a 186000 miles per second regardless of scale (it’s all relativity after all [:D] ) in a vacuum of course.
Alan
Why would the weight be 1/87 cubed? Why not 1/87?
The 1/87 cubed is a volume measurement.
Quite simple. Anything with mass occupies 3 dimensions and therefore a volume of space.
Andre
If you’re 1/87th the size , wouldn’t it also be 1/87th the weight?
I think the question should be, “How was spelling class today?”
But 186000 miles is a whole lot shorter in HO than it is in the real world. So according to your relativity it would be 87 times faster. Hence one would HAVE to run a fast clock and think how that would change E = MC^2.
But to do so is meaningless. All model trains have a scaled down weight just because they are smaller than the real thing. As this thread has really pointed out, to prototypically scale down weight gets into all the physics of mass, gravity, density, etc. Most of which we can’t (and really don’t want to) do. Would gravity be equal to that of a 1/87th earth? Is that calculated before or after making density adjustments if any?
No, because the NMRA weight recommendations have nothing to do with “scaling down” anything. The NMRA weights also are per car period - there is no concept of an empty car vs a loaded car. There was no attempt to be prototypical in anything with this recommendation, it is simply to get the cars to run well given the limitations of physics and technology.
No, all model trains have a scaled down proportion, not a scaled down weight.
My comment was an attempt to be humorus, and nothing else. Since you didn’t recognize this, I guess I’ll just go back to being disagreeable.
I think you might be on something on to something here. I did a little looking up on the internet after I posted and found out that weight is a force, or really a measurement of the pull of gravity (or attraction)on an object. And the force of gravity has a relationship to the size of the object doing the attracting. One interesting explanation is here: http://www.youtube.com/watch?v=grWG_U4sgS8.
When I was a kid, my first “scale” locomotive ( Don’t laugh - it was up from Tri-ang at the time) was a Mantua-Tyco GP20 which according to the reviews I saw had a drawbar pull of 2.2 ozs. Speaking to a friend who also worked on the prototype and having a fascination for tech things such as Tractive Effort, he told me that multiplying it by 87 cubed which in its case worked out to about 90,540 lbs as it was then (just double checked it with the calculator function) which in the case is about right.
The scale weight of a 4 oz freight car is about 80 tons but the lateral drag is not like the prototype which on the flat would be about 4 lbs per ton because the friction coefficient is so much higher… my two cents worth!
Regards from Aus
Trevor