Gravity gradient stabilization

[Aphobius]

I've tried to make a gravity gradient stabilized station.

Since it's that long I had some problems with the control (a.k.a. I couldn't control it at all), so I couldn't get in the correct attitude and give it the proper angular speed. So I just left it there a few hours to see what happens.

The orange fuel tanks are separate ships, I used 4x physics warp in game and after that I've speed up the video 30 times.

Even if it's not ... stabilized, the effects of the gravity gradient are obvious (one end is always closer to the planet than the other end).

Would be nice to see if we can get something to maintain it's attitude relative to the ground by using the gravity gradient, so you can try it and post videos if you want. Probably I'll also try to improve this one (make it longer, distribute the weight better, make it controllable so I can set the initial conditions better etc.).

[gchristopher]

Oh great! I was hoping that'd work.

Maybe try a KAS tether?

It'll lose orientation once the object goes on time warp rails, which forces a stop to angular rotation.

[vger]

Do gravity gradients actually work in KSP? I never would've thought the base physics was actually that complex.

[Aphobius]

Do gravity gradients actually work in KSP? I never would've thought the base physics was actually that complex.

They don't work for single ships, but here the orange tanks are separate ships. So if the whole ship is in circular orbit, the orange fuel tanks that are closer to the planet have a lower speed than it's required for a circular orbit so they try to fall, while the fuel tanks the are further away from the planet have a higher speed than it's required for a circular orbit so they are pulled higher.

But in my video the ship gets accelerated towards a vertical attitude and when it reaches a vertical attitude it already have a high angular speed so it keeps rotating and as a result that oscillation happens. If you set the initial conditions correctly, that oscillation shouldn't happen and it should remain in a vertical attitude.

Oh great! I was hoping that'd work.

Maybe try a KAS tether?

It'll lose orientation once the object goes on time warp rails, which forces a stop to angular rotation.

I usually don't use mods, but maybe I'll try some for this.

EDIT: About time warp, I haven't used time warp for this one either since it's removing the angular speed, as you've said. I left it like 10 hours on 4x physics warp.

Edited May 7, 2014 by Aphobius

[NecroBones]

That's awesome! Yeah, it's nice to see that objects can actually get tidally locked, even if it's not perfect. Very cool.

[magnemoe]

Gravity gradients should work as things in orbit move relatively to each other, this can be seen clearly during docking.

Guess the orbit is to fast for the effect to work, it must generate an force enough to rotate the ship every 30 minutes.

[mellojoe]

They don't work for single ships, but here the orange tanks are separate ships.

<--SNIP-->

I usually don't use mods,

How are they seperate ships, yet tethered together, and you aren't using mods?

[Grumman]

How are they seperate ships, yet tethered together, and you aren't using mods?

It looks like he has a box around the tanks, but not attached to them..

[gchristopher]

I usually don't use mods, but maybe I'll try some for this.

If I understand the KAS mod right, it gives you an adjustable length flexible tether with the option of being docked or undocked. If "undocked" works the way I think, the two connected vessels would retain separate centers of mass.

It reports some kind of force on the cable. It'd be neat to see if that corresponds with expected tension generated by a gravity gradient.

[Mosimir]

HoCgaming explain it here with KSP

[Aphobius]

Yeah, I have some kind of box around the fuel tanks.

I'll try that KAS mod.

[Tripzter]

Why not just a single tank and then add more mass on the sides of the tank?