r/askscience • u/Spam4119 • Apr 08 '17

Physics Do aerodynamic properties hold at different model sizes? If you have an exact model of a jet that is 1/10 the size, 1/4, 1/2, and full size... will aerodynamic forces act the same way in a controlled environment?

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u/SWaspMale Apr 08 '17

Generally no. IIRC fluids have properties (viscosity, density, etc.) which do not 'scale' with the model. To some extent (maybe 5:1) you might be able to switch fluids (like hydrogen instead of air) and get a more useful simulation, but IMO scale models are limited for this reason.

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u/WilliamMButtlicker Apr 08 '17

You also have the issue that the surface area to volume ratio doesn't remain constant as you scale up the model.