SPORE Mission Design - Georgia Tech SSDL - Georgia Institute of ...

this center of gravity requirement cannot be met for the 1U and 2x2U vehicles. A 6DOF model of the
SPORE entry trajectory was created using POSTII to assess dynamic stability during the hypersonic,
supersonic, and transonic entry regimes. The CG location for the 1U and 2x2U vehicles is given in Table
4.Figure 4depicts the coordinate system to locate the CG.
Table 4: Center of gravity location of the 1U and 2U SPORE vehicles. These values were input in the
POST model. The X CG /D max parameter provides comparison to the Mars Microprobe research completed
at Langley9.
X (mm) Y (mm) Z (mm) X CG /D max (%)
1U 143.3 2.74 -1.89 37.1%
2x2U 245.3 2.87 -1.05 40.6%
Figure 4.Coordinate system used to locate center of gravity.
The moment of inertia properties are needed for the 6 DOF model. These values are given in Table 5,
Table 5 for the 1U and 2x2U vehicles respectively. The moment of inertias were calculated about the
center of gravity using the coordinate system depicted in Figure 5.
Table 5.6 DOF vehicle moments of inertia for the 1U and 2x2U vehicles. These values were input in
the POST model.
I xx (kg-m 2 ) I yy (kg-m 2 ) I zz (kg-m 2 )
1U 0.1 0.082 0.089
2x2U 0.717 0.611 0.649