Here’s a whimsical observation – I’m building an RFM Sturmtiger (“full interior”) and just test-fitted metal tracks. Then I picked it up and was surprised enough by the new weight it nearly slipped out of my hand.
So I did a calculation - with all pieces in place it’ll weigh in at around 350 g., times 1:35 that’s 12.25 kilos.
The Sturmtiger’s fighting weight was 65 metric tons, divided by 1.35 that’s 1.86 metric tons.
Check my figures, if they’re correct it means the model is around 1/15th (6.67%) of actual scale-weight even with metal tracks.
Someone will tell me what the comparative densities of plastic vs. steel which should go a long way to explaining the discrepancy. But all of it?
And further, I’ve been musing whether anyone, anywhere, has produced/built a model of any kind that matches the scaled weight of the original? If anyone’s chasing absolute accuracy, they’ll need to reinforce their display cabinet a tad. Anyone for a Bismarck?
You’re forgetting that you’re dealing with a three-dimensional object here, not a one-dimensional line If you scale up an object, its volume increases by the scaling factor to the third power, and so its weight does as well. For example, if you have a one-litre cube, making it twice as large in all dimensions makes it 2³ times as big, so you now have a cube that holds eight litres. If these cubes were filled with water, the one-litre cube would weigh 1 kg while the double-sized one is 8 kg.
If you want to know the scale weight of a 1:35 scale model, therefore, divide the real weight not by 35 but by 35³, which is 42,875. Your Sturmtiger’s scale weight would be 65 ÷ 35³ = 0.0015 tonnes, or 1.5 kg.
Weight relates to volume not length
Simple exercise: Draw a square with 2 cm long sides, the surface area of that square is 2 x 2 cm = 4 cm.
Now draw a scaled down copy of that square, say 1:2 scale. The sides will now be 1 cm long and the surface area will be 1 x 1 cm = 1 square cm.
The relation between the areas is not the length scale 1:2, the area scale is 1:4.
The general rule is that the area scale is the square of the length scale, the surface area of your Sturmtiger is 1/35 x 1/35 = 1/1225th of the real thing.
The volume scale behaves in a similar way.
The volume of a cube with the sides 2 cm will be 2 x 2 x 2 = 8 cubic centimetres.
The scaled down cube with 1 cm sides will be 1 x 1 x 1 = 1 cubic centimetres.
The volume scale of the 1/35 kit is 1/42875 (1/(35 x 35 x 35)).
The scaled up weight of your Sturmtiger would be around 15 metric tons,
the remaining discrepancy is the density differences between plastic and steel and also the internal mass of the engine and gearboxes.
It has been quite warm here so maybe that’s affecting him. I should go around and take some soothing libations of G & T. Purely for medicinal purposes.
If you took a real Sturmtiger and scaled down every single part of it using the same materials for every nut, bolt, screw and washer. Every rubber hose, seal and gland, paint thickness and seat padding materials you would end up with a 1.5 kg object.
What I wrote is that if you scaled up the styrene kit and the metal tracks you would end up with a styrene and white metal behemoth weighing in at 15 tons.
The conclusion of both calculations is that your kit is underweight.
If you decided to replace the plastic hull, casemate and barrel with scale thickness items made of steel you would be hitting the proper scale weight.
We had a similar question back in the old forums, someone questioned the scale of his 1/96th scale Saturn rocket. No friggin way this little tube on my desk is 1/96th of the real thing.
Those who build radio control model ships know that the volume (displacement) scales with the cube of the length scale.
A 1/72 model of the PT-15 (100 tons displacement) would be horribly difficult to handle if the weight scaled with the same scale factor as the length, 1.39 tons is way too heavy for my
hobby desk.
Scaling with the cube scale gives me a weight limit of 268 grams,
barely possible with 4 AA batteries when I did it 40 years ago.
The rebuild will use AAA batteries which will allow weight for some other stuff.
Model companies can’t get the profiles or details correct, now Tim is expecting weight and ability to support said weight in a kit? Might need to touch some grass on the ground instead of smoking it.
O.K., now work out the dimensions and materials for the torsion bars to get it to sit right on non-road diorama base, and what materials you would need for the base…
M
If anyone is being triggered by any of the mathematical concepts used in this thread, I offer my services as a high school special education teacher to help get you on par with your peers in the general education environment.
There are 16 of them, though, so each would carry only just under 100 grammes (and that’s before deducting the weight of the wheels and the part of the track that rests on the ground). I don’t have any model Tiger suspension arms to test, but I’d think it’s much more likely they’ll take 100 g than 1.5 kg
Things would get dangerous if you pick the model up from one side while leaving the other resting on the table for a bit. My AFV Club Churchill AVRE with SBG bridge, that has 100 grammes in the back and the suspension adjusted to show it carrying the bridge, leaned on its rear three axles when the bridge was off. At one point when building it, I put the model down and one of the axles just broke, with a wheel going flying.
Sorry, but as an educator I am a mandated reporter so any attempts at suicide I have to report to the authorities so you can be taken in for a mental health evaluation.
If you scale up an object, its volume increases by the scaling factor to the third power, and so its weight does as well. For example, if you have a one-litre cube, making it twice as large in all dimensions makes it 2³ times as big, so you now have a cube that holds eight litres. If these cubes were filled with water, the one-litre cube would weigh 1 kg while the double-sized one is 8 kg.
i know what 2+2 is
