Touchdown points?

[dseagrav]

Since touchdown points are no longer a thing, how am I supposed to tell Orbiter (2015) that a rocket should stand on its tail?

 

[jedidia]

Touchdown points still are a thing. They can just be used to define a full convex hull, so your vessel should stay in whichever position you land it in... :shifty:

 

[dseagrav]

Is the order and position of points used with the new version of SetTouchdownPoints() identical to the old? That is, if I call the new SetTouchdownPoints with 3 points, and pass the same points I used previously, should that work?

When I try, the vessel is violently thrown into space instead.

 

[francisdrake]

The SetSize parameter defines the radius of a circumferrential sphere around the vessel.
The touchdown points should stick out of this sphere. It seems Orbiter 2015 is interpreting this more stringent than previous versions.

Otherwise the ground collision detection may give error results.
These points do not really need to represent any physical landing leg, or so.
Below is what I use for the Orion-MPCV:


SetSize (6);
...
SetTouchdownPoints( _V(0,-5, -4), _V(-5, 3, -4), _V( 5, 3,-4));

 

[dseagrav]

The code I had previously "works", but I have to find out how to use the new interface because I need to define an incompressible landing gear. (Is this possible even with the new interface?) When the Saturn 1st stage engines ignite, there is a device to hold the vehicle down until thrust has built up to full. We simulate this in 2010 by applying a large negative force to counteract the thrust. In the new version the default "landing gear" is compressible so the hold-down force pushes the vehicle into the ground. Reducing the force results in the vehicle lifting off early, balancing it exactly results in the vehicle bouncing on its "landing gear".

I wish I could just turn off the compression.

 

[francisdrake]

Ah, I did not know about that compressible landing gear!

Proposed hack:
Define a set of thrusters with zero thrust for the engine run-up.
These thrusters are like the real ones, with exhausts added, but just 0 thrust.

When it is time to lift off, delete these trusters, add new ones in the same place, having proper thrust this time.

Or you could create both thruster groups in the beginning, just switching the THGROUP_MAIN to the real ones at liftoff.

 

[dseagrav]

That might work. I'd have to work out how to make the fuel consumption the same or it will screw up my stage burn time. Getting that right in 2010 was a chore too.