A package launch system can be implemented to propel a package from an unmanned aerial vehicle (UAV) in a generally vertically descent trajectory, while the UAV is in motion. The package launch system can apply the force onto the package in a number of different ways. For example, flywheels, coils, and springs can generate the force that establishes the vertical descent path of the package. Further, the package delivery system can also monitor the package during its vertical descent. The package can be equipped with one or more control surfaces. Instructions can be transmitted from the UAV via an RF module that cause the one or more controls surfaces to alter the vertical descent path of the package to avoid obstructions or to regain a stable orientation.