hongshaorou/openrocket
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Implement inertia computations.

Browse Source
This commit is contained in:
kruland2607 2014-11-17 12:02:26 -06:00
parent 1dbff4a0dc
commit 34a2ca8984
1 changed files with 19 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
core/src/net/sf/openrocket/rocketcomponent/TubeFinSet.java
View File

@ -251,19 +251,33 @@ public class TubeFinSet extends ExternalComponent {
double halflength = length / 2; double halflength = length / 2;
if (fins == 1) { if (fins == 1) {
return baseRotation.transform( return baseRotation.transform(new Coordinate(halflength, getOuterRadius() + getBodyRadius(), 0, mass));
new Coordinate(halflength, getOuterRadius() + getBodyRadius(), 0, mass));
} else { } else {
return new Coordinate(halflength, 0, 0, mass); return baseRotation.transform(new Coordinate(halflength, 0, 0, mass));
} }
} }
@Override @Override
public double getLongitudinalUnitInertia() { public double getLongitudinalUnitInertia() {
// FIXME - this is very likely completely wrong // Logitudinal Unit Inertia for a single tube fin.
// 1/12 * (3 * (r1^2 + r2^2) + h^2) // 1/12 * (3 * (r1^2 + r2^2) + h^2)
return (3 * (MathUtil.pow2(getInnerRadius())) + MathUtil.pow2(getOuterRadius()) + MathUtil.pow2(getLength())) / 12; final double inertia = (3 * (MathUtil.pow2(getOuterRadius()) + MathUtil.pow2(getInnerRadius())) + MathUtil.pow2(getLength())) / 12;
if (fins == 1) {
return inertia;
}
// translate each to the center of mass.
final double hypot = getOuterRadius() + getBodyRadius();
final double finrotation = 2 * Math.PI / fins;
double angularoffset = 0.0;
double totalInertia = 0.0;
for (int i = 0; i < fins; i++) {
double offset = hypot * Math.cos(angularoffset);
totalInertia += inertia + MathUtil.pow2(offset);
angularoffset += finrotation;
}
return totalInertia;
} }
@Override @Override