Center of gravity shift parts

[Shepard]

Hi everyone.

After playing a bit of Orbiter in the XR-2 Ravenstar Spaceplace, I was wondering why there is no center of gravity shifting systems like in this ship for KSP. It will consist in in-line or radial blocks with a moving mass in it to keep the center of gravity of the vessel in the most stable position possible with the center of thrust and the center of lift. It would be very useful for planes and space shuttles, allowing much better control of the craft ( how many times my nice crafts started going insane when the fuel started to be low... ), but also let the game be more gentle with "exotic" looking creations without adding tons and tons of SAS blocks that weight too much and make the plane a pain to pilot when you want to turn.

Well, what do you think about it ?

[Kasuha]

You can pump fuel around the ship to change center of mass. Use larger number of smaller tanks for that to be the most effective.

The only small problem is that in-game physics do not account correctly for that way of shifting the center of mass - when doing so, center of mass moves in space instead of ship parts moving around center of mass. Under extreme circumstances it may have noticeable or even significant effect on your trajectory.

Edited October 26, 2013 by Kasuha

[Shepard]

And what do you do with Jet planes with almost one lenght of tanks, or with tanks placed side by side ? Your idea would almost make the plane even more unstable if you don't have a plugin that distribute the fuel correctly everywhere.

[Kasuha]

Of course you're going to have problems if you don't account for it in the ship design. You need to put air intakes and an engine on your plane to fly, right? Intakes facing forward, engine facing backwards. That's the drill. So if you want to change center of mass, you need to place the right device - correctly arranged fuel tanks - on it, too.

[Shepard]

That's the problem...

By placing the right elements at the right place, you may still have problems piloting the craft when the fuel is getting low if you don't add tons of SAS, making the craft too heavy to fly, then you'll have to start from scratch again....

[JoCRaM]

you need to place the right device - correctly arranged fuel tanks - on it, too.

this is what I use fuel ducts for - moving fuel toward he CoM - with 5 tanks pump 1 to 2, 2 and 4 to 3, and 5 to 4. (you have to pump boh ways, or you will become front heavy instead...)

Edited October 26, 2013 by JoCRaM
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[arq]

Reaction wheels can provide the same stabilizing effect through a different mechanism in stock. There are mods for robotic arms - maybe you could rig up something that way?

[Shepard]

Reaction wheels can provide the same stabilizing effect through a different mechanism in stock. There are mods for robotic arms - maybe you could rig up something that way?

The problem of reaction wheels, as I said in my first sentence, it is that you need lots of them to make your craft stable enough. So it will consume lots of energy, make the plane ridiculously heavy and insanely reactive in every turning attempt. With a center of mass shifting section, it won't help you craft turning like a reaction wheel ( a 0.18 SAS block ), but it will only help at stabilizing the plane without turning it into a 500t spin machine.

And don't talk about those crazy robotic parts that make your craft explode when you time warp...