Take the 2-minute tour ×  Kristian von Bengtson (on twitter, on
Wikipedia) of Copenhagen Suborbitals is building a downscaled
test item to test the design for their space capsule. He notes
that as volume and area scale down differently, he has to make
sure that his test results sre still applicable to the full-
scale item.  He asks on Wired if the following assumptions he
makes on the physical properties of his 1:3 scale model of a
space capsule are correct:    • to test buoyancy behaviour (does
it swim, in what position does it come to rest), he has to keep
the volume to mass ratio (i. e. the density) constant.   • to
test the forces on impact in the water, he has to keep the ratio
of inertia to impact area constant, and therefore add mass to
the model (because the volume, and therefore the mass, scales
down more quickly than the craft's cross section)  Are those
assumptions correct?  share|improve this question scale the
forces 1:3 and scale time 3:1 - that should do it – 
EnergyNumbers Dec 14 '12 at 8:21 Sh