Figure 4.

Rotation vs. pressure for an individual test of each of the three spiral designs in Figure 3, along with the spherical cap energy–balance model using torsional spring constant $\kappa$ = 0.06 N m, strain energy coefficient $\gamma$ = 30 J m⁻², and base radius r₀ = 0.038 m. Dashed lines indicate where the model extends beyond measured inflation pressures.