Orbital determination for spacecraft

[Sword7]

Hello folks,

I still am looking for orbital determination formula with specific speed and direction around massive object (planet) for spacecraft, etc. For example, I set a vector of speed and direction with small object like spacecraft, what does that happen with orbit around massive object like planet or moon?

Thanks,
Tim

 

[Chode]

Have a look at Appendix C in the Orbiter documentation (Orbiter.pdf).

Regards

 

[Sword7]

How about motion acceleration?

Have a look at Appendix C in the Orbiter documentation (Orbiter.pdf).

Regards

Ok, thanks for info. I looked into that chapter. How about motion calculation like acceleration? For example, I set small object with zero speed/direction, it would accelerate into the planet as free fall. With some speed/direction setting for spacecraft, it would accelerate around the planet as orbit then slow down....

Thanks again,
Tim

 

[Urwumpe]

Ok, thanks for info. I looked into that chapter. How about motion calculation like acceleration? For example, I set small object with zero speed/direction, it would accelerate into the planet as free fall. With some speed/direction setting for spacecraft, it would accelerate around the planet as orbit then slow down....

Thanks again,
Tim

That is done by the Kepler orbit equations.

 

[mikey451]

In the absence of other forces, two-body (i.e., a vessel plus a planet or moon or sun) acceleration is u/r^2, directed toward the central gravitational attraction. In the presence of other forces, acceleration in each axis is equal to the sum of the forces (including gravitational forces) divided by the mass, at non-relativistic speeds (or any speed, with the current orbiter equations). For two body situations, the equations can be expressed in more or less closed form (i.e., solvable in advance). For more complex situations, they have to be approximated, or solved iteratively, numerically.