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clarify comments

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This commit is contained in:
JoePfeiffer 2020-07-09 10:14:28 -06:00
parent 69e45029a2
commit e30eb4b523
1 changed files with 11 additions and 8 deletions
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19
core/src/net/sf/openrocket/rocketcomponent/FinSet.java
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@ -642,14 +642,14 @@ public abstract class FinSet extends ExternalComponent implements RingInstanceab
* *
* The process is the following: * The process is the following:
* *
* 1. Approximate a fin with a rectangular fin * 1. Approximate a fin with a rectangular thin plate
* *
* 2. The unitary moment of inertia of one fin is taken as the average * 2. The unitary moment of inertia of one fin is taken as the average
* of the unitary moments of inertia through its center perpendicular * of the unitary moments of inertia through its center perpendicular
* to the plane (Izz/M), and through its center parallel to the plane (Iyy/M) * to the plane (Izz/M), and through its center parallel to the plane (Iyy/M)
* *
* 3. If there are multiple fins, the inertia is shifted to the center of the * 3. If there are multiple fins, the inertia is shifted to the center of the
* FinSet. * FinSet using the Parallel Axis Theorem
*/ */
@Override @Override
public double getLongitudinalUnitInertia() { public double getLongitudinalUnitInertia() {
@ -684,10 +684,11 @@ public abstract class FinSet extends ExternalComponent implements RingInstanceab
if (finCount == 1) if (finCount == 1)
return inertia; return inertia;
// Move axis to center of FinSet. We need to apply parallel axis theorem // Move axis to center of FinSet. We need to apply the Parallel Axis Theorem
// to Izz, but not to Iyy (as the displacement as we move to the new axis // to Izz, but not to Iyy (as the displacement as we move to the new axis
// is along Y). Since our moment of inertial is the average of Iyy and Izz, // is along Y). Since our moment of inertia is the average of Iyy and Izz,
// this is accomplished by just weighting the transformation from the theorem by 1/2 // this is accomplished by just weighting the transformation from the theorem
// by 1/2
return inertia + MathUtil.pow2(MathUtil.safeSqrt(h2) / 2 + getBodyRadius()) / 2; return inertia + MathUtil.pow2(MathUtil.safeSqrt(h2) / 2 + getBodyRadius()) / 2;
} }
@ -696,9 +697,10 @@ public abstract class FinSet extends ExternalComponent implements RingInstanceab
* Return an approximation of the rotational unitary inertia of the fin set. * Return an approximation of the rotational unitary inertia of the fin set.
* The process is the following: * The process is the following:
* *
* 1. Approximate the fin with a rectangular fin and calculate the * 1. Approximate the fin with a rectangular thin plate
* unitary rotational inertia (Ixx/M) of the rectangular approximation, *
* about the center of the approximated fin. * 2. calculate the unitary rotational inertia (Ixx/M) of the
* rectangular approximation, about the center of the approximated fin.
* *
* 2. If there are multiple fins, shift the inertia axis to the center * 2. If there are multiple fins, shift the inertia axis to the center
* of the Finset. * of the Finset.
@ -728,6 +730,7 @@ public abstract class FinSet extends ExternalComponent implements RingInstanceab
if (finCount == 1) if (finCount == 1)
return inertia; return inertia;
// Move axis to center of FinSet using Parallel Axis Theorem
return inertia + MathUtil.pow2(MathUtil.safeSqrt(h2) / 2 + getBodyRadius()); return inertia + MathUtil.pow2(MathUtil.safeSqrt(h2) / 2 + getBodyRadius());
} }