   Implementing the RK4 for Projectile Motion with Air Resistance
  Hi all,I am writing (begging) for some assistance with implementing the RK4 (Runge Kutta Fourth Order) algorithm for projectile motion with air resistance. I have searched everywhere, read countless forums, but am yet to find a complete description.  There's lots of snippets of code but every time it seems to omit something or use a built in function.It should be a relatively simple 2D problem. Given initial velocity (Vo) and angle (theta), I just want to plot the projectiles pathVo = some numbertheta = some angleVox = Vo * cos(theta)Voy = Vo * sin(theta)Ax = (-R * Vx)Ay = -g (-R * Vy)where g is gravity, R is an air resistance constant.I know that I need to split up the equations for the RK4, or use an approximation for one quantity to use the RK4 for the other, but I just can't get my head around it.many thanksGeoff
  Have you looked over this?You just need to plug in the equations for acceleraiton: http://gafferongames.com/game-physics/integration-basics/