Scaling Area

[vonJaerschky]

Does anybody have the formula for scaling area? For instance if a full scale are has a wing area of 750 sq ft, and I want to build a 1/12 scale model, what will the wing area of the model be? It can't be as simple as dividing by 12, can it? I did try and find the formula on google, but maybe I'm just not punching in the right terminologies. Thanks for any help to the mathematically challenged. Do you divide by the scale factor squared, perhaps?

[slipstick]

Area = length x width. If length and width are each 1/12th then area is 1/144th.

As you say for area it's scale factor squared. If you wanted volume it would be scale factor cubed.

Steve

[biber]

Yes it's sqared.

So in that case you will be dividing it by 12^2 = 144.

biber

[vintage1]

And your target weight will be divided by 12 cubed..or in fact more, as if you keep to that, your scale airspeed will be root twelve slower, and that - unless you can use a slomo camera, whilst aerodynamically accurate, is usually too fast to be realistic for people not on amphetamines.. ;)

Compromises are called for. I try to go as light as possible to keep cruise speeds realistic, and then have excess thrust available for BIG loops, like the full size does, and as far as going round corners goes, well you just have to bank it over more to give the impression its going much faster and is much further away, and put some opposite rudder on to try and keep it up there..can look ugly that tho..knife edging round in a steeper bank than it wants to. Basically do your corners well away from the spectators :D

[richard hanson]

scaling weight?
A formula exists?
Maybe so - but getting a weight which flies well is NOT a result of scale factor
here is my own weight scale formula:
build it as light as you can with enough rigidity for flight -
It is physically impossible to make it too light--
Or restated :
it is a task which requires real care to make it light enough for good performance as a model .
Here are two rules for models - tested and proven
as the model gets smaller -- the difficulty in keeping weigh low enough increases
In making a craft larger - the difficulty in having adequate power increases.
It may be possible to come up with a formula which is practical for these conditions . I never tried (I don't know any math cept 'cornbread R square")

[vonJaerschky]

I tend to build pretty light. I am just bouncing some numbers around for a future project and have the data of the full sized aircraft, so just wanted some ball park wing areas in different scales so that I can come up with the best size to accomodate the features I want in the model and not wind up with a lead sled. Thanks for the replies, gents.

[HugePanic]

i am an air vehicle that doesn't change the flying weight when scaling!

what am i???

[vonJaerschky]

I would think any lighter than air craft with neutral buoyancy? Zeppelin, blimp, helium balloon, etc?

Prosit!

[JetPlaneFlyer]

Ahh... But a balloon / blimp or whatever does increase it's weight when it's size is increased (to the cube of the scaling factor)... It's just that it's weight is offset against it's buoyancy from the air it displaces (which also increases as a cube of the scale factor) ;)