For this unit, Charlie and I have chosen to make a mangonel. I expect this project to come with certain difficulties but in the end, the long design process will be worth it when our final product is successful. My main concern is the calculations that we have to make to ensure that our final product to actually work the way its supposed to. The dimensions and angles and especially the calculations involving tension have to be carefully made. There are certain issues that I expect to encounter during our design and building process. One big problem that we have already run into is the release system that we will use to fire the mangonel and an issue I think we will have to deal with soon is what will happen to the wood when the rope is at full tension. Although the process will be long and come with its difficulties it is essential that we deal with our problems so that our final design is good.