Rocket Lab has recovered the first stage of its dedicated small satellite launcher Electron twice by means of splashdown. The ability to reuse the entire first stage can reduce production cost at the current launch frequency and enable a higher launch rate. To lower the launch cost further, Rocket Lab is developing Mid-Air Recovery system for the first stage of the Electron. The research objective of this thesis is to develop a simulation tool for analyzing the launch performance of the Electron rocket and its first-stage recovery, involving mid-air recovery using an air-ram parachute and splashdown recovery using an unguided circular parachute. For the ascent phase, a two-stage rocket Simulink model is developed that implements quaternion representation of six-degrees-of freedom (6-DOF) equations of motion for custom variable mass in the Earth-centered Earth-fixed (ECEF) reference frame to simulate ascent trajectories. Another Simulink model is created to simulate the ballistic trajectory of the first stage after separation using quaternion representation of 6-DOF equations of motion for constant mass in the ECEF reference frame, particularly when first stage recovery is not implemented. It was found that he additional mass, which is required to transform the Electron’s first stage into a reusable one is 100 kg, with the parafoil accounting for 74 kg, the ballute 9 kg, and the remaining mass attributed to modifications such as the parachute attachment and release mechanism and for the circular parachute 71.5 kg with 22.8 kg for canopy, 35.3 kg for suspension lines and 13.4 kg actuators. The parafoil provides superior control, whereas the circular parachute is lighter and more straightforward in design. Consequently, if refurbishment costs are identical for both, the circular parachute emerges as the more advantageous choice.