Drop tower

A drop tower is an experimental facility that releases an instrumented package into free fall, providing a short interval of microgravity. The package and its contents accelerate together, greatly reducing the support forces that normally produce apparent weight. Gravity remains present. Evacuating the drop tube reduces air resistance and the resulting disturbance of the falling experiment.^[ref]

For release from rest through height $h$ with nearly constant gravitational acceleration $g$, $h=g{t}^2/2$, so $t=\sqrt{2h/g}$. A $132$-metre fall gives about $5.19$ seconds in this ideal model, consistent with the facility's reported $5.18$-second test interval. Such experiments reveal how surface tension, fluid flow and combustion behave when gravity-driven effects are suppressed.^[ref]