This project investigated and evaluated the louver covering the outlet cooling shaft of combat vehicle 90 together with two possible redesigns. The goal was to investigate the flow properties of the new design models on the louver and then compare how they performed with the current in-use standard louver. The design concepts included the current in-use standard louver, a modified version whose details cannot be disclosed due to company confidentiality and lastly a design arranging the standard louvre vanes in an octagonal pattern with the center completely sealed off. The model which cannot be disclosed due to confidentiality showed significant increases in pressure drop across the louvre compared to the other designs. The octagonal louvre performed similarly as the standard model which shows that there could be possible gains from placing the vanes in a rotational flow pattern. The octagonal model also indicated that only a fraction of the flow exits the louvre through the center. Indicating that sealing off the center does not cause any significant changes to the overall flow and thus it could be sealed off.