Hello all, This is my first post so be gentle. I am programming a ballistics related script to a predefined physics engine. I am no physicist nor a mathematician so my knowledge in these things is quite limited. To the point: I need to calculate the initial velocity needed to shoot a projectile for it to land to known distance. Let's assume that we are using a flat surface. The physics engine uses a quite simplified drag formula which is something like this: D = Dc * V^2, where Dc is the predefined drag coefficient for that projectile. We know... ... the angle of the gun ... the distance to the target. ... the drag coefficient for the projectile I would provide you with more information, but frankly I don't know what info is needed to make this work. Please ask me for anything you need to make this function. Thanks for your responses in advance.