  We demonstrate that the so-called pancake bounce of millimetric water
droplets on surfaces patterned with hydrophobic posts [Nat. Phys. 10, 515
(2014)] can be reproduced on larger scales. In our experiment, a bed of nails
plays the role of the structured surface and a water balloon models the water
droplet. The macroscopic version largely reproduces the features of the
microscopic experiment, including the Weber number dependence and the reduced
contact time for pancake bouncing. The scalability of the experiment confirms
the mechanisms of pancake bouncing, and allows us to measure the force exerted
on the surface during the bounce. The experiment is simple and inexpensive and
is an example where front-line research is accessible to student projects.
