A friend reminded me today of a discussion we once had regarding how much a model would weigh, if its weight was in proportion to the real thing. For example, I had just presented him with a model of the F-102A (that plane just won’t go away this week) he soloed in. He picked it up from the table and seemed to be weighing it (this guy is also a physicist, and works for NASA in Houston). It was a little Hasegawa 1/72 Deuce I did the best I could to make presentable. “The scaling is accurate, but I don’t think that includes the weight.”
In fact, he said, the model was a LOT lighter. That if it was scaled to 1/72 scale weight, it would be dense as steel or aluminum or dirt, or something like that.
My question is, let’s say were were concerned with scale weights as much as we are with length, width and height. How much would, say, a 1/48 scale Phantom weigh? It couldn’t be 1/48 the empty weight of the real thing, could it? On its face, it seems that you would just divide by 48, but I just find that intuitively screwy, since inches and pounds are completely unrelated quantitative measurements. Anyone know the answer to this utterly pointless exercise?
TOM
a 1/48 scale weight of Phantom would be (1/48)^3 = 1/110592 of the real thing.
Weight is proportional to volume, which is proportional to cubic of the dimension.
But it’s beyond me why your friend would comment on the “model being much lighter than the real thing” anyway since the model is plastic and the real thing is mostly metal.
Also don’t forget, if the weight was in proper scale, the plastic we use probably wouldn’t be able to bear the weight. The model would fall apart.
The variable in weight also depends on the fluid levels in the aircraft (hydraulic fluid, fuel) and the armament loadout.
After all, it’s fun and relaxing to build/recreate a project. If we built everything exactly to scale, I’d guess we’d all be working on some Defense Department aeronautical project.[:D]
The comment about the model not being in proportion to the weight of the real thing was precipitated by some dumb comment about the pains I went to in order to wring accuracy out of what is otherwise a very ancient kit with few parts and even less detail, but a good overall shape. My friend had looked underneath the fuselage to see if I’d included a small detail that appears on the bottom of real F-102s and bears the obscene name of part of a dog’s anatomy. I said, “The —'s on there. What did you want, scale weight too?”
Now, aren’t you sorry you asked. Oh, wait, I just read your post again. You didn’t ask.
Never mind.
Tom,
You were right the first time.
Were you to truly and correctly scale down a structure of any sort, it’s weight would also be scaled by that factor. Ergo, in 1/48 scale, a 1:1scale F-102 would be exactly 48 times smaller in ALL respects - height, length, span AND weight.
It’s simple physics - so I’d forget trying to worry about total scale “correctness” and just enjoy your builds.
Have a good day, man.
Well… the first site I got aafter googling f-4e and weight said that the basic mission weight of an F-4e was 41,487 lbs which would make your 1/48 Phantom weigh 864.3125 lbs.
HTH,
Mog
Yes, what Mog says is why, just estimating the math in my head, I couldn’t see it. I never planned to acually worry about the weight, Lee, it was just something I was curious about, sparked by my friends joking comment. In fact, he said at the time that it would be much heavier than the plastic it’s made of, and just think about it. If we made a 1/48 aircraft out of the same materials as a 1:1 aircraft, it would be heavier, even without an engine, avionics, a pair of 300 lb. ejection seats, fire control radar, and on and on.
That’s why I said it was a pointless excercise. And I think it would be virtually impossible to scale the weight of a 1/48 model without scaling all the constituent parts of the real thing in 1/48 and making them from the proper materials – metals, rubber, composites – as on a 1:1 plane. So it really is a pointless excercise, because it’s virtually impossible to calculate in any practical sense. But some computer geek out there with no girlfriend and lots of time on his hands will probably do it.
TOM
Because 1/48 in the modeling world means 1/48 of dimension. NOT 1/48 of volume. Weight is proportional to volume, not linear dimension. I’ve already said it in my first post.
not necessarily.
It’s very possible to make a 1/48 exact replica of the real thing in the near future. Given the way nanotech is going. Some of the advanced computer circuits are smaller than the diameter of a human hair. Also, micromachining can make rivets that your eyes can’t even see, let alone only 1/48 of the current ones.
But it’ll be a waste of money.
But calculation netherless is extremely easy. If you make all the components with exactly the same material (same density) and exactly 1/48 the linear dimension of the real thing, the replica would weigh EXACTLY 1/48^3 of the real thing. So if the real thing weighs 40000 lbs, the replica would weigh .36 lb.
Not really. The model can actually be heavier. It’s obvious there’s a point where the thickness of the scale model plastic shell (which can’t be made too thin) outweighs the sheet metal shell shrunk down a certain size, which has no theoretical limit. The difference can be even greater than the extra engines, flight control computers (that the real thing have but the model dont) if you scale down enough. That’s why a 1/48 plastic model kit can weigh more than .36 pounds. (provided you gave me the right weight of the real F 4).
Forget about the weight [banghead]; let’s just build models and be happy![:D]
Good plan, I’m getting a headach just thinking about it.
So what is the answer?
How much should Tom’s F102 weigh at 1/72nd scale at a full scale (empty) weight of 19,050 lbs? Source: http://www.aerospaceweb.org/aircraft/fighter/f102/
And, (not trying to complicate things here) but what should it weigh if it were a wind tunnel model, given that we can’t scale down air density to that effect?
By the way Tom, I hope your friend finally appreciated your effort to give him what I’m sure is a very fine model. Any pics?
stinger
Naw, this was ten years ago. I thought of it because I’d forgotten that model, and the guy I made it for just told me yesterday his cat smashed it, and that was the day after another pilot friend told me his wife knocked the F-101 and F-4 I’d made him off the mantle piece. Anyone ever notice how little the recipients of these presentation models, even the ones who ask for them, or commission them for a price, appreciate just what goes into making them? “It got smashed, can you send me another one?” Yep, if you can wait about six months, assuming I feel like building another crappy Hasegawa Deuce and making it look presentable. The Mongram 1/48 was too big for his desk. As for the weight, well, HOU is right about micromachines and such, and I’ve always felt that it will revolutionize our hobby. Will? It already has begun to. Look at these tools (expensive tools) in FSM made with CAD? Admittedly, I’m not about to pay $55 for a tool that does nothing but make tiny grab handles, but there it is if you want it. And parts. They will get smaller and smaller and have already shrunk below our ability to handle them in PE. We’re going to need neurosurgery equipment to look through in order to make a model one day. And that 1/48 Mustang with AM parts will cost us $186,472. Still, it will be fun to build.
TOM
Oops - I completely missed Hou’s post.
Sorry to hear of the demise of your hard work Shark. I know what you mean, though. Some people have no sense of, or even respect for what goes into making a model. Even if you had just built it out of box, without any research or care put into the assembly, it deserved a safer place than one accessible to a cat, or a careless…well, never mind.
On the subject of micro circuits, I recently saw on TV where Intel is able to lay down a circuit on an ATOMIC level. Just a single string of atoms. Amazing.
Anyway, glad to see you have the right attitude. Keep on building!
stinger
Sharkskin, you’re right about some people who don’t understand all the time and effort put in to building a good looking model. So far I’ve only done one model for a presentation and the SSgt I built it for was happy beyond belief.[:)] I have displayed my own work on my desk before and some people ask , how long did it take to build and come back shocked when I tell the manhours. They thought I just “slapped” these things together.