• dynmic analysis of atmospheric reentry
• Entry-burn analysis
• Lanciatore riutilizzabile
• Landing-burn analysis
• Razzo recuperabile
• recoverable launch vector
• Reusable Launch Vehicle
• RLV
• thermal analysis of a recovery rocket

Re-usable launch vehicle are increasingly important in the space sector and they could take the market lead once low refurbishment costs and high reliability are guaranteed. This work contains the preliminary redesign and analysis of an expandable rocket to convert it into a reusable one. The objective of this thesis is to analyze the feasibility of recovering at least the first stage, studying its descending dynamic, assessing whether it can reach ground with vertical orientation and almost zero speed or not. Moreover, the mechanical and heat loads are of particular interest. The SpaceX' Falcon 9 is taken as reference, being it the primary example of a successful reusable launch vehicle and since its I-stage has been many times proved to be recoverable. Based on their example, retro-propulsion is here used for braking and landing of the I-stage. Once a reference mission is selected, mass and velocity considerations are used to obtain an estimation of the propellant mass needed for re-entry, to update the first stage structural mass to account for landing mechanism and to calculate the new payload carriable in the same reference orbit. This is closely connected to the re-entry dynamic for which a 2-D motion with 3 degrees of freedom is used. Four fins located at the top of the first stage act as passive stabilizers, while no active control system is present. The ignition of the retro-propulsion maneuver can be selected in function of the descending Mach number and of the altitude. Different sets of altitude-Mach number are analyzed to optimize this maneuver and the optimal one is then used for the whole process of redesign. Lastly, a thermal analysis on the whole object is conducted exploiting two different models -one of which oversimplifies the retro-propulsion maneuver- and comparing them to show how this maneuver significantly impact on the I-stage thermal loads. Apart from the results of the specific case analyzed, what emerges from this study is a flexible code adaptable to various expandable 2-stage rockets for starting studying their first stage redesign and re-entry. The flexibility stands in the possibility of choosing several different reference missions through the total $\Delta V$ required for the ascending phase. Moreover it is possible to explore different retro-propulsion maneuvers assessing the mechanical and thermal loads the structure may suffer and choosing the optimal one, therefore playing a solid work as a preliminary analysis.