Recovery Phase
The phase that requires the least amount of physics is the Recovery Phase. Using the formulas of kinetics, you can accurately predict the landing location of the rocket. Important external factors that are important to consider are weather, wind speeds, and geography of landing location. For predicting the landing location, the Drag equation becomes handy once again, as well as Newton's Second Law. Its important, during the planning phase, to consider the velocity of the descent that the parachute allows. Too small of a parachute, and the rocket may come down to quickly, damaging or even destroying the rocket, making the recovery phase a disappointing finale. Too large, and the parachute may not deploy in time, leading to little to no slowing of the descent.
Follow the Phases of a Rocket Launch for a Successful launch and get out there and have fun launching!