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Modify FinSetCalc to only produce result for one fin, to be summed in

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BarrowmanCalculator

Modify BarrowmanCalculator to actually sum fin nonaxial forces

Modify FinSetCalcTest to sum fins in test3Fin() and test4Fin()

Extra bonus:  if at some point we allow fins to be other than radially
symmetrical, this code should still work (not tested)
This commit is contained in:
JoePfeiffer 2019-02-11 15:37:21 -07:00
parent 13f7c583fd
commit eb3a129e67
4 changed files with 43 additions and 59 deletions
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1
core/src/net/sf/openrocket/aerodynamics/AerodynamicForces.java
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@ -392,7 +392,6 @@ public class AerodynamicForces implements Cloneable, Monitorable {
}
public AerodynamicForces merge(AerodynamicForces other) {
this.cp = cp.average(other.getCP());
this.CNa = CNa + other.getCNa();
this.CN = CN + other.getCN();

35
core/src/net/sf/openrocket/aerodynamics/BarrowmanCalculator.java
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@ -194,27 +194,20 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
final ArrayList<InstanceContext> contextList = entry.getValue();
for(InstanceContext context: contextList ) {
// since FinSetCalc calculates forces for entire FinSet
// only consider first fin in each set (happily,
// in each instance of a PodSet or similar
// instanceable RocketComponent with childre, the
// child FinSets all start numbering with 0
if (!(comp instanceof FinSet) || (context.instanceNumber == 0)) {
AerodynamicForces instanceForces = new AerodynamicForces().zero();
calcObj.calculateNonaxialForces(conditions, context.transform, instanceForces, warnings);
Coordinate cp_comp = instanceForces.getCP();
Coordinate cp_abs = context.transform.transform(cp_comp);
if ((comp instanceof FinSet) && (((FinSet)comp).getFinCount() > 2))
cp_abs = cp_abs.setY(0.0).setZ(0.0);
instanceForces.setCP(cp_abs);
double CN_instanced = instanceForces.getCN();
instanceForces.setCm(CN_instanced * instanceForces.getCP().x / conditions.getRefLength());
// System.err.println("instanceForces=" + instanceForces);
assemblyForces.merge(instanceForces);
}
AerodynamicForces instanceForces = new AerodynamicForces().zero();
calcObj.calculateNonaxialForces(conditions, context.transform, instanceForces, warnings);
Coordinate cp_comp = instanceForces.getCP();
Coordinate cp_abs = context.transform.transform(cp_comp);
if ((comp instanceof FinSet) && (((FinSet)comp).getFinCount() > 2))
cp_abs = cp_abs.setY(0.0).setZ(0.0);
instanceForces.setCP(cp_abs);
double CN_instanced = instanceForces.getCN();
instanceForces.setCm(CN_instanced * instanceForces.getCP().x / conditions.getRefLength());
// System.err.println("instanceForces=" + instanceForces);
assemblyForces.merge(instanceForces);
}
}
}

13
core/src/net/sf/openrocket/aerodynamics/barrowman/FinSetCalc.java
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@ -117,18 +117,7 @@ public class FinSetCalc extends RocketComponentCalc {
double angle = baseRotation + transform.getXrotation();
// Compute basic CNa without interference effects
if (finCount == 1 || finCount == 2) {
// Basic CNa from geometry
double mul = 0;
for (int i = 0; i < finCount; i++) {
mul += MathUtil.pow2(Math.sin(theta - angle));
angle += 2 * Math.PI / finCount;
}
cna = cna1 * mul;
} else {
// Basic CNa assuming full efficiency
cna = cna1 * finCount / 2.0;
}
cna = cna1 * MathUtil.pow2(Math.sin(theta - angle));
// logger.debug("Component cna = {}", cna);

53
core/test/net/sf/openrocket/aerodynamics/FinSetCalcTest.java
View File

@ -38,6 +38,27 @@ public class FinSetCalcTest {
// }
}
private AerodynamicForces sumFins(TrapezoidFinSet fins, Rocket rocket)
{
FlightConfiguration config = rocket.getSelectedConfiguration();
FlightConditions conditions = new FlightConditions(config);
WarningSet warnings = new WarningSet();
AerodynamicForces assemblyForces = new AerodynamicForces().zero();
AerodynamicForces componentForces = new AerodynamicForces();
FinSetCalc calcObj = new FinSetCalc( fins );
// Need to sum forces for fins
for (Integer i = 0; i < fins.getFinCount(); i++) {
calcObj.calculateNonaxialForces(conditions,
Transformation.rotate_x(Math.PI * i / fins.getFinCount()),
componentForces, warnings);
assemblyForces.merge(componentForces);
}
return assemblyForces;
}
@Test
public void test3Fin() {
Rocket rocket = TestRockets.makeEstesAlphaIII();
@ -49,19 +70,10 @@ public class FinSetCalcTest {
assertEquals(" Estes Alpha III fins have wrong tip chord:", 0.03, fins.getTipChord(), EPSILON);
assertEquals(" Estes Alpha III fins have wrong sweep: ", 0.02, fins.getSweep(), EPSILON);
assertEquals(" Estes Alpha III fins have wrong height: ", 0.05, fins.getHeight(), EPSILON);
FlightConfiguration config = rocket.getSelectedConfiguration();
Transformation transform = Transformation.IDENTITY;
FlightConditions conditions = new FlightConditions(config);
WarningSet warnings = new WarningSet();
AerodynamicForces forces = new AerodynamicForces();
FinSetCalc calcObj = new FinSetCalc( fins );
// vvv TEST MEH! vvv
calcObj.calculateNonaxialForces(conditions, transform, forces, warnings);
// ^^^
// get the forces for the three fins
AerodynamicForces forces = sumFins(fins, rocket);
double exp_cna_fins = 24.146933;
double exp_cpx_fins = 0.0193484;
@ -84,18 +96,9 @@ public class FinSetCalcTest {
assertEquals(" Estes Alpha III fins have wrong tip chord:", 0.03, fins.getTipChord(), EPSILON);
assertEquals(" Estes Alpha III fins have wrong sweep: ", 0.02, fins.getSweep(), EPSILON);
assertEquals(" Estes Alpha III fins have wrong height: ", 0.05, fins.getHeight(), EPSILON);
FlightConfiguration config = rocket.getSelectedConfiguration();
Transformation transform = Transformation.IDENTITY;
FlightConditions conditions = new FlightConditions(config);
WarningSet warnings = new WarningSet();
AerodynamicForces forces = new AerodynamicForces();
FinSetCalc calcObj = new FinSetCalc( fins );
// vvv TEST MEH! vvv
calcObj.calculateNonaxialForces(conditions, transform, forces, warnings);
// ^^^
// get the forces for the four fins
AerodynamicForces forces = sumFins(fins, rocket);
double exp_cna_fins = 32.195911;
double exp_cpx_fins = 0.0193484;