Space plane spinning when engine is changed.

[dazhat]

When I turn off my turbojet and activate my rocket, my space planes frequently spin round suddenly. Can anyone explain why?

[Sᴄɪɴᴛɪʟʟᴀᴛᴏʀ]

The plane will spin if the center of thrust from the engine isn't aligned with the center of mass of the craft. Use the icons in the lower left corner of the SPH and VAB to find out. They only show for the stats for first stage though so you will need to adjust your staging to see the alignment for your rocket engine.

[Ben Kerman]

Can you post a picture and/or .craft file of your plane?

[dazhat]

It flys fine on either the rocket engine or the 4 turbojets but when I make the transition from one to the other at 17,000m - 20,000m it tends to spin suddenly.

Click here for album with more pictures.

[Ben Kerman]

Strange, I can't spot anything wrong.

When switching, you do turn off all engines at the same time, right?

[Payload]

Strange, I can't spot anything wrong.

When switching, you do turn off all engines at the same time, right?

That's probably it.

He needs to check that the action group actually turns off all the engines. They can get borked if you remove them and put them back. Even if the actions say they are set up you have to re-do them.

[AndersSchm]

Sounds to me like you are turning your jets off late (or not turning them off properly). Make sure you are turning off your jets at a lower altitude, I used to get the jets firing intermittently due to limited oxygen at high altitude which causes the plane to spin. I started flying on rocket only above 10k and it fixed it.

Best to bind an action group to turn them off at the same time.

You should be able to hear them "popping" if this is what is causing the issue.

[dazhat]

Strange, I can't spot anything wrong.

When switching, you do turn off all engines at the same time, right?

Yes I turn them all off with an action group.

I turn on my rocket first then switch off the jets just after.

It isn't flame outs.

[Narrov]

If the engines flame out before you turn them off then you will go into a spin. You need to make sure that you activate your rockets before you turn your engines off and before the jets flame out. Then you should remain stable.