Stabilization of Rocket flight

[chrisparypa]

Hi, can someone please help me stabilize rocket launches ?

There is no problem when I build rocket with Kerbals on board. I can press T and climbing is stable etc,

But when I build something without Kerbals on the board, some kind of satellite etc. here is my problem, I have almost zero control over the stability and moment of the rocket. I can correct course, rocket is going up nice and then slowly falling on the side. I can't do gravity turn because I have no or very little control over the rocket. Yes I did use vectored engines, I used tail fins. sometimes if I'm lucky rocket will get to the higher altitude, even higher than that and I can't control spin, can't turn my rocket in space to pro/retrograde, how to make the rocket controllable without Kerbals on the board. I was trying small, vbig, faster, slower rockets... same deal...

Thank you for your help guys !

[Lazerman34170]

Unmanned capsules have less torque than manned capsules. This means its harder to control them. Try putting an ASAS or SAS module on there and see if that helps.

[Vanamonde]

You can also add more probe cores, since they're pretty small, and each one adds more control torque.

[RocketPilot573]

Did you try using winglets and RCS?

[Procyon]

O would suggest an ASAS module for control of the gimbaled engines / fins / rcs and an SAS module or 2 to add some torque. depending on the rocket size, and I am assuming fairly small as its for a probe, the Asas and SAS would be sufficient, for larger rockets fins for in atmosphere and extra sas module or 2( only need one Asas for any ship, and fins do not help once you are out of atmosphere) for very larger rockets all the preceding will help, but you may need rsc for direct thrust control, I personally try to avoid using rcs for control if I can at all help it, that's just me tho

Edit: don't forget power for the probes so you don't go dead in the water, so to speak.

[chrisparypa]

I did try fins, winglets, rcs, sas, asas.

RCS is not very helpful in atmosphere. I have a problem in the > FL800 then of course I can use RCS and ship is controllable. in the atmosphere very little control, almost nothing...

I'm new in the Kerbal World but I'm not ignorant I'm testing, checking, trying to build. No problem with Orbital maneuvers, now I'm trying to send probe to orbit the Mun

[stupid_chris]

Actually, all probe cores/command modules have (very nearly) the same torque/weight ratio, meaning they all have the same ability to give angular momentum. Your problem probably comes from how you design your ships. In atmosphere, add winglets. The RV8 (or something like that I never remember) give you the most control surfaces. Also try disabling the gimbal on the outer engines of your craft. It's really all you can do to stabilize it. It might also be a strutting problem. Also make sure your probe cores are always powered, so don't forget to extend your solar panels.

Could you post a picture of one of your manned launchers and one of your unmanned launchers?

Edited June 5, 2013 by stupid_chris

[Sᴄɪɴᴛɪʟʟᴀᴛᴏʀ]

Try making your rocket as symmetrical and balanced as possible. That way your rocket will be less inclined to tilt in a given direction.

[falofonos]

General tips :-

If you have more than one engine with gimbals running at once, shut off gimbals on all but the most central one.

4 Winglets near the bottom of the rocket works pretty well.

Making sure that mass and drag are symmetrical will help a great deal.

General observations :-

With high powered rocket engines, they can sometimes dance around producing a lot more lateral thrust than they should. On some of my rockets this has become so severe that the whole thing shakes itself to bits or goes into an uncontrollable spin. Only way I have found to fix this is to place the shortest smaller diameter fuel tank at the base of the main tank, then the rocket engine, then 6 struts holding the engine to the large tank radially.

[rosenkranz]

Since probe cores have trouble controlling anything larger than a satellite it's important to shed mass as you go. It sounds like your insertion stage is to big.

If you really need a probe core to control a large mass, I'd suggest an empty mk1pod or something like it. There is a control moment gyro mod on spaceport that will help a lot. It's essentially a pod with no crew capacity (about the same size and mass of a mk1 but stackable). It's advantage is it won't autopopulate a kerbal on board at launch.