• blowdown pressurization
• monopropellant
• propellant tank
• service module

Propellant tankage and its arrangement have a large effect upon liquid-propellant rocket engine design and propulsion systems integration. Having dual, identical tanks has more advantages (Size of Bladder or diaphragm, tank hemisphere size) compared with a single tank.
The main objective of the project is to design and analyze the propellant tanks and service module to which the two propellant tanks are arranged with supports. The design of the monopropellant tanks and service module is done based on the technical specification obtained from the upcoming PLATO (Planetary Transits and Oscillation of stars) spacecraft. The diaphragm tanks contain an elastomeric diaphragm separating the liquid propellant from the pressurization gas.
The tank geometric parameters are calculated from the given propellant mass and internal pressure of the tank with a blowdown ratio. The three-dimensional model is done using CATIA software. The model is then transferred to ANSYS to perform analysis. The static Thermal and structural analysis are performed with temperatures, internal pressure, external pressure, and acceleration conditions.
The modal and eigenvalue buckling analysis is performed in a prestressed condition linked from static structural analysis.
The results obtained are concluded, the design is structural feasible because the resultant von mises stress is less than the yield stress. The maximum deformation is observed near welded joints and they are well within allowable limits. Mode one and two frequency is primarily considered for the design of support structures thickness and cross-section. mode one is improved to 54Hz to make the structure safe. The buckling is found in the cylinder part of the propellant tank. To improve the buckling values the thickness can be further increased. In future work, the model can be improved with the modal analsys and fatigue analsys.