Question falling through the ground

[pilotpercy]

hey guys, almost finished the first part of my new addon "Thor". ive been doing some flight tests to see how it flys and ive run into a little problem.

ive set all the landing points (there are 3) and when the scenario starts it looks fine, on runway 33 at the cape. as soon as any thrust is applied it falls through the ground by about 2m. ive tried ajusting the COG (im using SC3) but this makes no difference.

also, this problem may be related, when running along on this "sub-ground" the breaks work in the wrong direction, ie application of the right break causes a turn to the left.

any ideas??

cheers

Ash

 

[dbeachy1]

The problem is that your touchdown points need to be modified to match the mesh. Touchdown points are specified in center-of-mesh-relative coordinates, so you need to decrease the Y coordinate value of the three points. For example, if your Y touchdown coordinate is -2.1, decreasing it to -3.1 would make the ship sit one meter higher above the ground. To get the precise value you need to get the mesh coordinates of each gear wheel (when deployed, of course) and use those values for touchdown points.

For more information, take a look at SetTouchdownPoints in Orbitersdk\doc\API_Reference.pdf on page 30.

 

[pilotpercy]

ive sorted the touchdown "LANDPOINTX" and the sim starts with the craft sat on the runway in the correct position. its only when i apply power the the problem occours

 

[dbeachy1]

In that case it sounds like your touchdown points are changing for some reason. Are you raising the gear automatically or something? Touchdown points are what Orbiter uses to determine how the ship sits on the ground, so if the ship is "sinking into the ground" while taxiing, then the touchdown points must be changing for some reason (i.e., like when the gear is raised).

 

[pilotpercy]

this craft has 3 unretractable skids, its just got me thinking if ive missed something out, but im sure i havent

 

[kwan3217]

Are you sure that you have your touchdown points in the right order? Check the docs, but it needs to be something like nose wheel, left wheel, right wheel. If you go nose wheel, right wheel, left wheel, then I think that the spacecraft will flip over when it gets unstuck from the ground and the simulator starts managing forces. Like it says on the Shuttle Carrier Aircraft, "Place [Shuttle] Here - Black Side Down". Since not all vehicles are space shuttles, and it's not always the black side that goes down, Orbiter figures out which side goes down from cross products of the touchdown points.

Apologies for resurrecting an old thread, but it didn't look like this had been answered yet.