Ship is balanced but still tilts *Please Help*

[Phesired]

I have just started career mode and have made a rocket, it has scientific experiments on the top to provide me with the points. I have stumbled across a issue with my last few rockets. The center of mass is right in the middle of my ship as you can see in the screen shot. It always has a tilt and I wouldn't be asking this if it didn't do the same with my other last few rockets. Can you please give me a suggestion on why this is happening and how to fix it?

[Johnno]

Your ship is so tall that even the smallest vibration can start tilting it. Add some control surfaces if you can (canards/winglets) or reaction wheels. Also widening the base (first stage) wouldn't hurt since then the gimballed engines would have more effect.

The tilting happens because the mass above your CoM has such a long 'lever' (distance) that the mass/control below it has a hard time controlling it. Adding struts between the stages should help as well since then the whole craft would be more rigid.

[FlamedSteak]

First thing I'd do is add struts to stiffen the structure.

[Sirine]

"career mode" Just put more command pod on top. They give the "reaction wheels values". Help a lot in stabilize the launch.

and you need 100 times more the battery. They are light, just put all that you can.

[Vanamonde]

It is the length of the rocket that is your main problem. If you've invented radial decouplers, I'd suggest dismantling the lowest stage and re-arranging its parts as a ring around the second stage. Some struts between the first and second stage would also help.

[The Destroyer]

"career mode" Just put more command pod on top. They give the "reaction wheels values". Help a lot in stabilize the launch.

and you need 100 times more the battery. They are light, just put all that you can.

You don't really use electricchrage, except for transmitting data, but I expect he returns. The only thing that (slowly) consumes EC, is the SAS.

[Kasuha]

As people above said, KSP physics favor short and wide ships over long and thin. I can see you have radial decouplers already so instead of putting your lowest stage at the very bottom, put it around the middle stage. That will make your ship much more stable.

If you have engines with thrust vectoring (LV-T45, i.e. those which provide 200 thrust rather than 215), use these. They will help keeping your ship straight.

[EtherDragon]

Also, you are probably getting uneven drag across the tops of your boosters. As soon as your ship leans over a little, the flat tops of those boosters will cause uneven atmospheric drag; so cap 'em off. Since your rocket is so tall, definitely add aerodynamic fins (with control surfaces) on the bottom.

Lastly, are you using fuel lines for asparagus staging? If so, double check they are set up correctly, and that you aren't burning fuel unevenly.

[numerobis]

The tilting happens because the mass above your CoM has such a long 'lever' (distance) that the mass/control below it has a hard time controlling it.

It's a bit more complicated than that. A long lever in itself isn't a problem -- if fact, you want control inputs (vectoring thrust, or winglets) on a long lever or you won't be able to control your spacecraft. The issue is if the lever is floppy. Then it's like your engines are pushing on a string, and the engines will soon be pointing some direction other than up.

[numerobis]

you are probably getting uneven drag across the tops of your boosters. As soon as your ship leans over a little, the flat tops of those boosters will cause uneven atmospheric drag; so cap 'em off.

That's not how drag works in stock KSP. Drag affects each part individually without regard to how you would expect air to flow; it's as if each part was individually flying through the air on its own. The rocket has all parts with 0.2 drag, so for KSP drag purposes it may as well be a perfect sphere. The caps work by having lower drag per unit mass, so the caps feel less acceleration due to drag than do other parts, which causes a torque. But the force isn't big (the caps are probably 1% of the mass of your rocket) so they don't have much effect at straightening out your flight -- as evidenced by the fact that people could fly rockets with caps in previous versions even though those caps had high drag. Basically, they're just cosmetic.

Aerospikes used to have low drag also, and those have mass, so they caused problems: they really wanted to be flying ahead of your rocket, even if you would normally put them on the bottom. Useful as retrorockets on Eve though, for that very reason; this is no longer the case in 0.22 (sadly). SRBs have high drag, so if as most people do you put them on the bottom, they help you lift off straight. But really, the way to affect drag is to put winglets on your rocket.

[Taki117]

Wiglets help, (AV-R8's if you have them) I would put them on each stage, if you have launch stabilizers those help too. MOAR STRUTS! Also, if you can set up asparagus staging (I forget where in the tech tree the external fuel duct is exactly) you could also try activating SAS on the launch pad before launch, as well as adding more reaction wheels (Either by using pods, or the inline reaction wheels under the control tab) It seems to me that your rocket is actually too top heavy (Those boosters on the side of your lander) And, thanks to the .22 update Nosecones are useful! Use them. Here's a screen shot of one of my early launchers. It could make orbit, but not much else. Unstable as all get out, but nothing a little manual control couldn't fix.

With a few minor modifications (Landing legs and more fuel in the stack, and control fins on the boosters) This ship took me all the way to Minmus.

[Mykill Metal]

Your rocket is WAYYYYYYY too big. Make it as small as the upper third until you unlock bigger SAS units.

Edited October 26, 2013 by Mykill Metal
deleted accidental quote