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# If 1 in. is to 1 ft. what is 1 lb. to I am building a ...

If 1 in. is = to 1 ft. what is 1 lb. = to ? I am building a scale model of a boak and a unit conversion to convert weight ( weight to scale ), Model scale is 1 in. = 1 ft. What I need for example is if a engin weight is 615 lb. in life size what would the weight be in the model ? I have had some answers of .083 = 1 lb. but this cant be right if you take .083 x 615 = 51.045. If uou put a 51 lb. engine on a model that is 8 in. wide and 22 ft. long it would sink. Thanks for any help.Customer
Basically, you need to use the square of the scale as the divisor for the scale weight.

You can't go straight scale because the buoyancy is exponential and not a straight and level measure.

So, in this case, your motor would not be 51.045 lbs.

Instead, you would take your scale of 1/12 with a divisor of 12 and square the 12 to 144. You can then divide 615 by 144 for a scale engine weight of 4.27 lbs.

This is a fairly generic rule of thumb and you may need to massage it to meet your needs but this will generally work. Obviously, a 4.27 lb engine will be a much better fit for your model buoyancy-wise.
Customer: replied 10 years ago.
so 1 lb. to scale would be 0.00694 ? thanksCustomer
Actually, I beg to differ.

The weight is a function of the volume, not the area, of any particular element of the model. You would thus use the CUBE of the model scale, not the square.

Having done many a civil engineering model in my pre-retirement life, I feel particularly confident of this recommendation.
Customer: replied 10 years ago.
Ok so how do I CUBE the model scale of 1 in. = 1 ft.? thanksCustomer
If the original of an item being modeled weighs 615 pounds, and you use the same material, at a scale of 1:12, the scale item would weigh 1 / (12 * 12 * 12 ) or 1/1728 as much as the original...

615/1728 = 0.356 pounds, just over 1/3 of a pound.

Each dimension - length, width and height - is 1/12 of the original, so the volume (and weight) is 1/1728 of the original.
The Scribbler, Lamentably Modest Publications
Category: Entertainment
Satisfied Customers: 1387
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