Would an empty 49,100 pound freight car, like a PS-1 boxcar, really scale down to ~1,023 pounds in O scale?
Thanks,
Mario
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No, the scale ratio is stated for any one dimension, whereas the models are built in three dimensions. To find the scale weight of an O scale model - assuming it was built using exactly the same materials in perfect scale dimensions - you would divide the prototype weight by the scale factor cubed, i.e. 48^3 or 110592. So, 49100 / 110592 = 0.444 lbs, or 7.1 ounces.
perfect... Thank you.
So the 119,900 maximum weight on the above freight car would be 17 ounces (1.08 pounds).
Thanks!
Mario
Which is just above the NMRA standard for an O scale 40' car 
but better to be over than under.
but better to be over than under.Originally Posted by CentralFan1976:
perfect... Thank you.
So the 119,900 maximum weight on the above freight car would be 17 ounces (1.08 pounds).
Thanks!
Mario
Glad I could help... it's one of those nuggets of information that I learned in the live steam world. Although the weight of a scale model is pretty much academic in O scale, it is a very useful thing to know when dealing with large scale live steam locomotives. Since they tend to be built out of the same materials with all the same parts as their full-size brethren, it is a quick way to find an approximate weight for the model. I say approximate, since the boilers on the models are generally built much heavier than scale for safety's sake, thus adding a bit of weight to the finished model. But, I digress... it is an interesting thing to calculate for any size model!
Originally Posted by CentralFan1976
So the 119,900 maximum weight on the above freight car would be 17 ounces (1.08 pounds).
The 119,900 pounds is the maximum weight of the load That could be put into the car. The maximum weight of the car would be the light weight plus the load limit. In this case 169,000 pounds. I believe this is an old value for a car with 5 1/2 X 10 journals.
Originally Posted by WindupGuy:
No, the scale ratio is stated for any one dimension, whereas the models are built in three dimensions. To find the scale weight of an O scale model - assuming it was built using exactly the same materials in perfect scale dimensions - you would divide the prototype weight by the scale factor cubed, i.e. 48^3 or 110592. So, 49100 / 110592 = 0.444 lbs, or 7.1 ounces.
While this is fundamentally correct to scale volumes with specific densities, for modeling and simulation it does not work. Lets say for instance you are modeling an airfoil in a wind tunnel and you wanted to know how much lift the real thing would generate. There are fudge factors built in to scaling the viscosity and air density. Lift does not just scale. So you really need to explain what it is you are trying to figure. how much weight a scale loco should pull to match a prototype? There are significantly more things going on then just scaling the weight, like rolling forces. I hate to be a killjoy but that is engineering for you. You can also think about this brain teaser from a google interview question "You are shrunk to the height of a nickel and your mass is proportionally reduced so as to maintain your original density. You are then thrown into an empty glass blender. The blades will start moving in 60 seconds. What do you do?" The answer is jump out. funny things happen when you scale.
Thank you all!
Lets say for instance you are modeling an airfoil in a wind tunnel and you wanted to know how much lift the real thing would generate.
Which we are not doing in O scale model railroading.
The correct number to answer the OP's question is prototype weight divided by 48 cubed or 110,592.
