Another noob problem....

[cs.mate]

Hi! I`m playing KSP a month ago. I had a few launches, travelled to the Mun, etc.

>I`m starting to build my first orbital station, so i need more effective rockets to bring the parts up there. But my rockets are starting to spin, roll and falling. Unstable. I can`t enable vectoring thrust - that`s why. Even if the engine has got it already enabled. I tried toggling gimbal, free/lock gimbal, SAS enable/disable.

Pls help! What am i (not) doing?

>>sorry for bad english

Edited October 13, 2013 by cs.mate

[Peppe]

Compare the lift section of your rockets to these:

http://forum.kerbalspaceprogram.com/threads/33381-0-20-2-Zenith-rocket-family-%28modernised-for-0-20-x-with-perfect-subassembly%29

Or just use the Zenith lifters from the thread above. I think it is more fun to make yourself, but i learned a lot just looking at the zenith rockets.

I started my own family inspired by the Zenith line that works well from 10-30 ton payloads -- optimized for cost and then part count. Worked on 50 ton the other night and seems to be time to add struts... lots of struts or orange tanks, both of which I dislike.

[Cydonian Monk]

Hi!

A screenshot of the craft you're having issues with will help, but I suspect your problem is due to a high center of mass. More thrust and more powerful engines will help a bit, but getting your center of mass lower will likely solve most of your issues.

It's all a very delicate balancing act, and launching large station pieces can sometimes really throw the balance off.

Good luck! (And let us know how you solve it!)

[nhnifong]

Vectoring thrust is enabled by default. However, having too many vectoring engines can be a problem, especially with mechjeb. modded vectoring engines with too much range are also a problem too (novapunch). Wings on your payload can cause your rocket to flip, avoid that. when in doubt, add more struts.

[rpayne88]

Are you using control surfaces? It seems that when they are used with SAS, they cause control problems. I believe this is due to a bug in the game causing them to produce a small amount of asymetic thrust (AKA, the infini-glide bug.)

If it is truly thrust vectoring, make sure you are not using the stock aerospike or the LVT-30. Neither of these engines have thrust vectoring. Also, if you are launching before trying to enable thrust vectoring, ensure that there has not been a structural failure between the pod and the engine by pressing F3.

As far as your English, its better than most people in my country (the U.S.)

[cs.mate]

Thanks for the replies well here are some pictures showing my problem. I made an ultra-simple craft to show that, so it contains a FL-T800 fuel tank, an LV-T45 engine a guidance unit and some batteries. You can see it on the first picture. I enabled the engine, added minimal trust and toggled the gimbal. On the second picture notice the roll, yaw and pitch controlls are off-set (lower left corner). So i already control my trust along the axes (or not? ) but the engine`s thrust vectoring seems to be offline. How can i do something with the engines like on the third picture?

[Peppe]

Gimble on the LV-T45 is 1 degree. The difference is very slight.

I setup the same test and can see a slight change in the thrust direction.

center:

hold "d" (see the yaw pegged):

Nozzle moves a couple of pixels. I would not count on this for control of your craft.

I found two things useful in my lifters: Struts to eliminate engines moving from their own thrust. And adding any of the reaction wheel type parts -- winglets might help as well, but i mainly stick to reaction wheels.

In either case my lifters from 5-40 ton use only the LV-T30 (no vector range).

[cs.mate]

Thanks well my conlusion is: i`m not relying on thrust vectoring anymore, i`m using reaction wheels. A couple of wheels can stabilize the whole craft, so i tested it and it worked anyway it`s true that i must use more strunts becouse the wheels are sometimes ... pretty strong. So they are sometimes destroying the whole craft. For example breaking it into two parts.

Anyway thanks everyone!