My ship keeps flipping over from an unknown torque

[kendfrey]

I'm having trouble with one of my ships. I've balanced the mass and thrust to the best of my ability. Yet it is still torquing when I throttle up.

The sepratrons are only to get it off the ground. I originally ran into this issue halfway to space. Only the two main engines were there.

The SAS and command pod's reaction wheels could keep it relatively controlled until about 1/3 to 1/2 throttle. Above that, it spun uncontrollably. Shutting the engines off removed the torque and I could stop the spinning again.

Does anyone know why it would be acting this way?

Craft file: http://www.filedropper.com/munlandertest

Edited October 13, 2013 by kendfrey

[Dispatcher]

It looks like you are running your hand loops laterally from the capsule hand loops before installing a ladder. That may be throwing your balance and drag off just enough to produce the unwanted effects. You might want to rearrange all radial mounted hardware to allow for a straight climb down. I actually go further in my designs. I place ladders in 3 symmetry to ensure more balance, but most people here probably would just use the one ladder, properly placed relative to the capsule hand holds.

Edited October 12, 2013 by Dispatcher
balance & drag

[KvickFlygarn87]

Okay, who let the Kraken in?

[kendfrey]

I see no way possible that those ladders could be the cause. They don't change the centre of mass much, and the ship flips over in a different direction. It spins as though the left engine (on the picture) is stronger. Exactly along the pitch axis. It's a powerful spinning, too, not something that would be caused by a slight misalignment of the centre of mass.

[zxczxczbfg]

I think you can just surround the capsule with a "collar" of vertically-orientated handholds. They'll balance better than a half-collar of horizontal ones, and Kerbals can move sideways across ladders just fine. Eightfold symmetry should do the trick. Also, be sure that if you're using MechJeb that you install the AR202 unit parallel to the axis of thrust and pointed upwards. Also, be sure to right-click your main command pod and chose "control from here" from the list.

[Blue]

Such phantom torque comes from part clipping--unwanted and uncontrollable forces of two physics meshes interacting. It is likely as mentioned, the lateral ladders mounted on the decoupler.

Sometimes these phantom forces are additive, meaning they only occur when there's an input force, and the collision of meshes compounds upon the input force, such as when engines are active.

Other times the phantom forces are random, meaning simply because of the part clipping, force is generated from "nowhere". This is more common with improper landing gear attachment.

[kendfrey]

Ohh, that makes sense, Blue. I didn't have any luck with my little green men climbing across vertical ladders so far, but I'll try again.

[mythbusters844]

Try locking the gimbals for the two engines on the sides.

[Wayfare]

By the looks of it, I'd say you're firing your engines into your rover. Does it torque in one particular direction?

[Mokmo]

is one of the engines thrusting onto a part underneath it ? i don't know what distances are necessary, but maybe rotate the rover 90 degrees so it's in in the engines thrust's way.

[kendfrey]

It appears to be the exhaust hitting the rover. I pointed the engines outward, and the rotation was mostly eliminated.

My messages don't seem to be going through very fast. I think it's been almost half an hour since I posted the first reply and it still hasn't appeared. Sorry about that.

[DerekL1963]

Try locking the gimbals for the two engines on the sides.

I was about to say the same thing... lock the gimbals on the radial engines, and/or move them down below the CoM.

I usually rotate the capsule (but NOT the upper docking port, that becomes my "control from here" part) to line it up with wherever my ladders need to go.

And I'd love to see the .craft for this when it's finished.

[SRV Ron]

The problem would appear to be the engines on the COM. Either lower them below the COM or raise them above. Vectoring is not working properly which is causing control issues. The capsule SAS should be more then sufficient for control so lock the gimbals.