Problem Vessel lands gently then flips quickly or turns

[tauruslittrow84]

What vessel specs or parameters would cause the following:

I land the craft gently with hover thrusters, shut down the engines, all is well for a split second and then the ship turns or flips about its z axis about 45 degrees to a new position. My ship is a tail sitter. Its been hard to find td points that allow it to land on its tail on landing legs with thrust vector down (z) like a lunar module. In other words you'd be looking north as you land... shut down the engines without crashing and in a split second the vessel flips to look west.

 

[jedidia]

Are you running any autopilots?

 

[Lisias]

Are you sure you set the touchdown points correctly? I get sometihing like this when I mistyped one of the touchpoints, sending it to the vessel nose...

When you deploy the landing legs, you reset the touchdown points? What do you do when you undeploy them?

In another situation, I was calling the initialization routine on the PostStep callback, what was undoing the touchdown points after the gear deploy.

 

[fred18]

mmmh, have you tried to set to 0 the surface Friction Coefficients?

 

[francisdrake]

Try commenting out the touchdown points. Let the vessel sit down on its size sphere, the one defined in SetSize(). See what happens. I had funny experiences with touchdown points just barely sticking out of this virtual sphere.

 

[tauruslittrow84]

Tried setting the Surface Friction to .8 instead of .5...now I'll try the other way to .1 or zero. However, I found that my vessel allows me to keep the thruster on very low without lift. So if I slowly lower the thruster after TD it doest flip. However, I was trying to "kill" the motor the instant it touched or a foot above the surface and it would settle nicely then flip. As for TD points, they are just crazy exporting from Anim8or. I would export in every possible axis config. to try to have my vessel sit on its tail in Orbiter. One way seemed to work. But orbiter doesn't really like it. At times I've had to have my TD points completely OUT of the virtual sphere or it would stand ridulously on its head??? :0 Last night I put the TD points at the very edges of where its legs were it an equalateral triangle...even tho it has 4 legs... with the zero origin of of xyz sitting centrally under its nozzle...first time it stood straight up with the points defined reasonably. no change on the flips really tho...now the set size parameter is probably in meters, is it not?...how does that translate to a quadrant graph of Vector3 points? each interger step is a meter or not? Right now mine is an arbitrarily-defined 9 meter ship, after a truer 3 or 5 meter ship, was not stopping the flipping...however Mesh Wizard shows my landing leg circle footprint to be extending to the "fours" in x,y and 6 and -6 in the z tall- wise. So if that's 4 meters I'll have to try that as the size of the ship or 2 meter radius.

 

[C3PO]

If the touchdown points are in the wrong order the craft will "try" to settle upside down.

..\Orbiter\Doc\OrbiterConfig.pdf page 21.