Flight Question change the orbiter elements with the thruster

[weiqi]

I have added some thrusters to the satellite which I have created by myself. However, when I use the thrusters to change the Orbiter, the satellite just rolled around. I don't know what's the matter behind this, could anyone help me? Thank you!

 

[Tommy]

Possibly the thrust vector is not aligned with the COG? Or double check your thruster groupings? You really don't give us much info to use diagnosing this.

 

[Zatnikitelman]

Ok, is this a Spacecraft3 vessel or a .dll vessel?
If the former, did you specify an EX_MAIN section?
If the latter, how have you defined the thrusters in the source file?

 

[weiqi]

Ok, is this a Spacecraft3 vessel or a .dll vessel?
If the former, did you specify an EX_MAIN section?
If the latter, how have you defined the thrusters in the source file?

Thank you for paying attention to my question. It's a .dll vessel. If the thruster force vector doesn't pass through the satellite's center of gravity, it will make an angular accleration, don't think so? So I want to know what's the defination of the center of gravity in Orbiter or what should I do to find the coordinate of the grabity center?

Thanks for your help!

 

[tblaxland]

So I want to know what's the defination of the center of gravity in Orbiter or what should I do to find the coordinate of the grabity center?

The centre of gravity is always {0,0,0} in local vessel coordinates. If you want to avoid a thruster making angular accelerations the thruster must act through that point or have a pair (or more) of thrusters so that their torque balances out. For example, these would be OK:

1. Thruster attack point {0,0,-2}, thruster direction {0,0,1}.
2. Thruster attack points {-1,0,-2},{1,0,-2}, thruster direction {0,0,1}.