Originally Posted by
Top_Gunn
The argument that the "scale speed" should be 1/4 of the speed of the full size plane seems obvious at first, but is it? A quarter scale model has (roughly?) 1/16 of the surface area of the full-scale plane and 1/64 the volume. A quarter scale plane sitting on the runway next to the full-scale version looks tiny in comparison. I suspect that a quarter-scale model flying at a quarter of the speed of the full-scale version would seem to someone on the ground to be going unreasonably fast. I don't have a solution, but it does seem that picking the linear dimension as the standard is arbitrary.
I would argue the model looks tiny next to the full scale because for the very reason I explained above. As for the other example, it's got to be at both 1/4 the speed AND 1/4 the distance to appear correct. At a distance the eye sees everything as an outline. And surface area is just linear dimensions. Let me do some thinking on that. The other very big factor in vision and perception is what else is in the field of view.
I don't know that volume makes sense, since at any distance we don't "see" the depth of the object.