I hope some one can help me figure out how to define the touchdown points for 2016.

I have looked at the Delta Glider. I have a red cube at the touchdown points.

ShuttleA

So it looks like the touchdown points are also defining the shape of the vessel?

So with the older version it was 3 points. Center and left and right rear. It told rotation and direction.

But the Shuttle A has a rectangle of the pads touching the ground.

from the sdk:

So we get the vector 3 point. But the other values I don't understand.

I have looked at the Delta Glider. I have a red cube at the touchdown points.

Code:

```
static const DWORD ntdvtx_geardown = 13;
static TOUCHDOWNVTX tdvtx_geardown[ntdvtx_geardown] = {
{_V( 0 ,-2.57,10 ), 1e6, 1e5, 1.6, 0.1},
{_V(-3.5 ,-2.57,-1 ), 1e6, 1e5, 3.0, 0.2},
{_V( 3.5 ,-2.57,-1 ), 1e6, 1e5, 3.0, 0.2},
{_V(-8.5 ,-0.3 ,-7.05), 1e7, 1e5, 3.0},
{_V( 8.5 ,-0.3 ,-7.05), 1e7, 1e5, 3.0},
{_V(-8.5 ,-0.4 ,-3 ), 1e7, 1e5, 3.0},
{_V( 8.5 ,-0.4 ,-3 ), 1e7, 1e5, 3.0},
{_V(-8.85, 2.3 ,-5.05), 1e7, 1e5, 3.0},
{_V( 8.85, 2.3 ,-5.05), 1e7, 1e5, 3.0},
{_V(-8.85, 2.3 ,-7.05), 1e7, 1e5, 3.0},
{_V( 8.85, 2.3 ,-7.05), 1e7, 1e5, 3.0},
{_V( 0 , 2 , 6.2 ), 1e7, 1e5, 3.0},
{_V( 0 ,-0.6 ,10.65), 1e7, 1e5, 3.0}
};
```

Code:

```
static const int ntdvtx = 16;
static TOUCHDOWNVTX tdvtx[ntdvtx] = {
{_V(-3 ,-3.05, 12.5), 3.5e6, 3.5e5, 3},
{_V(-3 ,-3.05,-13.5), 3e6, 3e5, 3},
{_V( 3 ,-3.05,-13.5), 3e6, 3e5, 3},
{_V( 3 ,-3.05, 12.5), 3.5e6, 3.5e5, 3},
{_V(-7.7, 0 ,-0.4 ), 3e7, 3e6, 3},
{_V( 7.7, 0 ,-0.4 ), 3e7, 3e6, 3},
{_V(-1.5, 3 ,13.5 ), 3e7, 3e6, 3},
{_V( 1.5, 3 ,13.5 ), 3e7, 3e6, 3},
{_V(-1.3, 2.8 ,17 ), 3e7, 3e6, 3},
{_V( 1.3, 2.8 ,17 ), 3e7, 3e6, 3},
{_V(-1.8, 0 ,18.3 ), 3e7, 3e6, 3},
{_V( 1.8, 0 ,18.3 ), 3e7, 3e6, 3},
{_V(-1.9, 2.2 ,-13.8), 3e7, 3e6, 3},
{_V( 1.9, 2.2 ,-13.8), 3e7, 3e6, 3},
{_V(-3.3, 0 ,-14.9), 3e7, 3e6, 3},
{_V( 3.3, 0 ,-14.9), 3e7, 3e6, 3}
};
```

So it looks like the touchdown points are also defining the shape of the vessel?

So with the older version it was 3 points. Center and left and right rear. It told rotation and direction.

But the Shuttle A has a rectangle of the pads touching the ground.

from the sdk:

Code:

`• VECTOR3 pos collision point position (vessel frame) • double stiffness suspension stiffness coefﬁcient • double damping suspension damping coefﬁcient • double mu isotropic/lateral friction coefﬁcient • double mu_lng longitudinal friction coefﬁcient (only used for ﬁrst 3 points)`

Code:

```
17.57.3.327 voidVESSEL::SetTouchdownPoints( constVECTOR3&pt1, constVECTOR3&pt2, constVECTOR3&pt3 ) const
Deﬁnes the three points deﬁning the vessel's ground contact plane.
Deprecated This method has been replaced by VESSEL::SetTouchdownPoints(const TOUCHDOWNVTX∗,DW← ORD)const Parameters pt1 touchdown point of nose wheel (or equivalent) pt2 touchdown point of left main wheel (or equivalent) pt3 touchdown point of right main wheel (or equivalent)
Note
The points are the positions at which the vessel's undercarriage (or equivalent) touches the surface, speciﬁed in local vessel coordinates. The order of points is signiﬁcant since it deﬁnes the direction of the normal. The points should be speciﬁed such that the cross product pt3-pt1 x pt2-pt1 deﬁnes the horizon "up" direction for the landed vessel (given a left-handed coordinate system). Modifying the touchdown points during the simulation while the vessel is on the ground can result in jumps due to instantaneous position changes (inﬁnite acceleration). To avoid this, the
touchdown points should be modiﬁed gradually by small amounts over time (proportional to simulation time steps). This method is retained only for backward compatibility. Vessels should now use Set← TouchdownPoints(const TOUCHDOWNVTX∗,DWORD)const to deﬁne a convex hull of touchdown points. The touchdown stiffness and damping parameters are guessed according to the vessel empty mass. Therefore, SetTouchdownPoints should be called after deﬁning the empty vessel mass with SetEmptyMass.
```

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