Complex motion equation (projectile with changing mass and thrust)

[kaycha]

I need an equation to predict the flight path of a changing mass projectile under changing thrust. Any thoughts?

 

[A.T.]

I need an equation to predict the flight path of a changing mass projectile under changing thrust. Any thoughts?

General as stated, you have to do numerical integration of Newtons laws of motion. For specific thrust & mass profiles there might an analytical solution.

 

[bigfooted]

The usual starting point is the Tsiolkovsky rocket equation:
https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
Let us know if this is what you are looking for; if not, please refine your question.