1:144, 1:72, 1:48, and 1:24 are all multiples of 12. It makes sense if you’re using English units. 1:48 means one scale inch equals 4 feet, and something similar applies for all the other ones.
But then we have 1:32. Not 1:36, which would seemingly make a lot more sense. Not 1:30, which would at least land halfway between one foot and the next.
Using scales evolved over time, across different subjects and companies that made models or kits.
1/32 goes back to a popular size for toy soldiers, established in the 1890s by a couple of the largest manufacturers in Great Britain. That size is 54mm, and those makers chose to use it, because figures in that size fit well with some popular brands of toy trains. 54mm, as a size, is roughly equivalent to 1/32 as a scale.
But even then, there were variations. One maker measured the size from the soles of a figure’s feet to the top of its head, without any hat or headgear. Another chose to measure from the figure’s eyes to the soles of its feet. And once we get to plastic models, we can see variations from one maker’s model of a subject to the next maker’s. We can see variations in a scale within one model company’s catalog, too.
The other scales in use have their own somewhat similar origin stories. This one comes from toy cars, or slot cars, or car companies’ demo models. That one comes from a common size or scale used by ship model builders, and so on.
So, there’s not a rhyme or reason, as there might have been had someone decided, “I’m going to produce models, and the size will be a constantly accurately reduced proportion of the real thing.” It evolved via a more or less natural process.
Becaus of the natural breakdown of inches on scales and rulers most likely: 1/2, 1/4, 1/8, 1/16, 1/32. If the kit designers measure their subject in inches, it is easily converted to 32nds of an inch in scale.
1/32 is 3/8"=1’-0" on the architectural scale. 1/24 is 1/2"=1’-0".
1/35, according to urban legend, is something Tamiya pulled out from under the tatami mat. And the model world has ever since been divided between armor scale and airplane scale, like night and day.
And then ICM, Border Models and others overturned the apple cart by making 1/35 airplanes and 1/32 helos.
My understanding is that since inches are typically divided into 1/8ths, 1/16ths or 1/32nds, the scaling of old time models were ofgten done using one of these units as equal to the scale unit. As such, many old ship models were either 1/8th inch to the foot (1/96 scale) or 1/16th inch to the foot (or 1/192 scale). Similarly for larger models 1/8, 1/16, or 1/32 scales were similarly easy to use.
I recall reading an interview years ago with one of the engineers who worked for Revell in its earliest years…apologies that I cannot remember the name of said gentleman…who suggested the likelihood that the three common American scales were multiples of 1.5 (32 x 1.5 = 48, 48 x 1.5 = 72) because drawings could be easily pantographed up or down from one scale to the other.
For anyone under the age of 60 or so who doesn’t know what a pantograph is…look it up. In the days before the easy manipulation of computer imagery, they were handy gadgets often used by draftsmen and designers.
“Just what I hear’d,” as the old saying goes… [:D]
I still have a pantograph up in the loft. Use it every once in a while for odd jobs. Also had a slide rule that I gave to my grandson last year. He’s having a ball with it. He’ll be graduating from college next year.
My age group were taught to use a slide rule at school, just when some bright spark invented a plastic box with buttons on the front that made the slide rule obsolete overnight! I still have a slide rule, but have long since forgotten how to use it - I hope your grandson finds it useful!
I know it’s a little off the OP’s question as to 32, but I always keep the rule you quoted in mind when detailing. Would you REALLY see that 1:72 rivet on a plane 72-144 feet away (assuming 1-2’ viewing)?
My only exposure to slide rules was when flying 1:1 aircraft. The E6B “Whiz Wheel” is basically a rotating slide rule. I didn’t shed a tear when they were made obsolete by electronics.
My high school math class was literally the last year in which – in that district, at least – the slide rule was taught. In that long-ago age (1974), calculators were not allowed to be used for tests or exams…though slide rules were.
The laugh is, my dad…who was a lighting engineer…had taught my siblings and I to use slide rules while we were still in elementary school. I had a neat circular pocket-sized one I used all through jr. and sr. high.
No pocket-protector though. I was a nerd…but not a geek. [:D]
Heh heh, my dad was a civil engineer, and bequeathed me his slide rule. I never learned how to use it though. My mom used to use an abacus, but again I never learned. I got my first calculator in sixth grade, circa 1976. It had a red LED display and four functions. I am a Failed Asian for sure! Fail-ure. Disappointment. [:P]
I still have my college sliderule. Didn’t get a calculator until I was working on my first professional job. What a great invention! It would add and subtract as well as multiply and divide. Yeah, you could do a form of add/subtract with a slide rule using logs, but it was more trouble than it was worth and not very accurate.
You did have to be a little careful with those early calculators as many of them didn’t have an algebraic operatic system. You could get some odd results if not paying attention.[:O]
I remember when those things came out. They cost a small fortune back then and I wasn’t allowed to use it for school work or at school. It really killed my chance of getting a decent score at my last math class in 8th grade. I was never that good at math.
I do have a slide ruler from the Air Force. It was used by loadmasters to compute cargo and lace it in the correct position on the cargo floor. This one is configured for the C-130E.