Delivery drop rate modulation

An unmanned aerial vehicle (UAV) can deliver a package to a delivery destination. Packages delivered by a UAV may be lowered towards the ground while the UAV continues to fly rather than the UAV landing on the ground and releasing the package. Packages may sway during lowering as a result of wind or movement of the UAV. By modulating a rate of descent of a package, a package sway may mitigated. The lowering mechanism includes wrapping a tether in various directions around the package such that the package rotates in a first and second direction as the package descends. Additionally, a rip-strip lowering mechanism that separates under tension to lower the package and a rappel mechanism that slides the package down a tether may be used. Accordingly, the tether can control a descent of the package assembly.