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Move tumble drag calculations into BasicTumbleStepper and eliminate BasicTumbleStatus

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This commit is contained in:
JoePfeiffer 2023-04-21 11:37:05 -06:00
parent b6aaa3857a
commit 77d4bc890f
2 changed files with 68 additions and 90 deletions
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85
core/src/net/sf/openrocket/simulation/BasicTumbleStatus.java
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@ -1,85 +0,0 @@
package net.sf.openrocket.simulation;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Map;
import net.sf.openrocket.rocketcomponent.FinSet;
import net.sf.openrocket.rocketcomponent.FlightConfiguration;
import net.sf.openrocket.rocketcomponent.InstanceContext;
import net.sf.openrocket.rocketcomponent.InstanceMap;
import net.sf.openrocket.rocketcomponent.Rocket;
import net.sf.openrocket.rocketcomponent.RocketComponent;
import net.sf.openrocket.rocketcomponent.SymmetricComponent;
public class BasicTumbleStatus extends SimulationStatus {
// Magic constants from techdoc.pdf
private final static double cDFin = 1.42;
private final static double cDBt = 0.56;
// Fin efficiency. Index is number of fins. The 0th entry is arbitrary and used to
// offset the indexes so finEff[1] is the coefficient for one fin from the table in techdoc.pdf
private final static double[] finEff = { 0.0, 0.5, 1.0, 1.41, 1.81, 1.73, 1.90, 1.85 };
private final double cd;
public BasicTumbleStatus(FlightConfiguration configuration,
SimulationConditions simulationConditions) {
super(configuration, simulationConditions);
this.cd = computeTumbleCD();
}
public BasicTumbleStatus(SimulationStatus orig) {
super(orig);
if (orig instanceof BasicTumbleStatus) {
this.cd = ((BasicTumbleStatus) orig).cd;
} else {
this.cd = computeTumbleCD();
}
}
public double getCD() {
return cd;
}
private double computeTumbleCD() {
// Computed based on Sampo's experimentation as documented in the pdf.
// compute the fin and body tube projected areas
double aFins = 0.0;
double aBt = 0.0;
final InstanceMap imap = this.getConfiguration().getActiveInstances();
for(Map.Entry<RocketComponent, ArrayList<InstanceContext>> entry: imap.entrySet() ) {
final RocketComponent component = entry.getKey();
if (!component.isAerodynamic()) {
continue;
}
// iterate across component instances
final ArrayList<InstanceContext> contextList = entry.getValue();
for(InstanceContext context: contextList ) {
if (component instanceof FinSet) {
final FinSet finComponent = ((FinSet) component);
final double finArea = finComponent.getPlanformArea();
int finCount = finComponent.getFinCount();
// check bounds on finCount.
if (finCount >= finEff.length) {
finCount = finEff.length - 1;
}
aFins += finArea * finEff[finCount] / finComponent.getFinCount();
} else if (component instanceof SymmetricComponent) {
aBt += ((SymmetricComponent) component).getComponentPlanformArea();
}
}
}
return (cDFin * aFins + cDBt * aBt)/getConfiguration().getReferenceArea();
}
}

73
core/src/net/sf/openrocket/simulation/BasicTumbleStepper.java
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@ -1,5 +1,16 @@
package net.sf.openrocket.simulation; package net.sf.openrocket.simulation;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Map;
import net.sf.openrocket.rocketcomponent.FinSet;
import net.sf.openrocket.rocketcomponent.FlightConfiguration;
import net.sf.openrocket.rocketcomponent.InstanceContext;
import net.sf.openrocket.rocketcomponent.InstanceMap;
import net.sf.openrocket.rocketcomponent.Rocket;
import net.sf.openrocket.rocketcomponent.RocketComponent;
import net.sf.openrocket.rocketcomponent.SymmetricComponent;
import net.sf.openrocket.models.atmosphere.AtmosphericConditions; import net.sf.openrocket.models.atmosphere.AtmosphericConditions;
import net.sf.openrocket.simulation.exception.SimulationException; import net.sf.openrocket.simulation.exception.SimulationException;
@ -12,14 +23,66 @@ public class BasicTumbleStepper extends AbstractSimulationStepper {
private static final double RECOVERY_TIME_STEP = 0.5; private static final double RECOVERY_TIME_STEP = 0.5;
// Magic constants from techdoc.pdf
private final static double cDFin = 1.42;
private final static double cDBt = 0.56;
// Fin efficiency. Index is number of fins. The 0th entry is arbitrary and used to
// offset the indexes so finEff[1] is the coefficient for one fin from the table in techdoc.pdf
private final static double[] finEff = { 0.0, 0.5, 1.0, 1.41, 1.81, 1.73, 1.90, 1.85 };
private double cd;
@Override @Override
public SimulationStatus initialize(SimulationStatus original) { public SimulationStatus initialize(SimulationStatus status) {
BasicTumbleStatus status = new BasicTumbleStatus(original); this.cd = computeTumbleCD(status);
status.setWarnings(original.getWarnings());
return status; return status;
} }
private double getCD() {
return cd;
}
private double computeTumbleCD(SimulationStatus status) {
// Computed based on Sampo's experimentation as documented in the pdf.
// compute the fin and body tube projected areas
double aFins = 0.0;
double aBt = 0.0;
final InstanceMap imap = status.getConfiguration().getActiveInstances();
for(Map.Entry<RocketComponent, ArrayList<InstanceContext>> entry: imap.entrySet() ) {
final RocketComponent component = entry.getKey();
if (!component.isAerodynamic()) {
continue;
}
// iterate across component instances
final ArrayList<InstanceContext> contextList = entry.getValue();
for(InstanceContext context: contextList ) {
if (component instanceof FinSet) {
final FinSet finComponent = ((FinSet) component);
final double finArea = finComponent.getPlanformArea();
int finCount = finComponent.getFinCount();
// check bounds on finCount.
if (finCount >= finEff.length) {
finCount = finEff.length - 1;
}
aFins += finArea * finEff[finCount] / finComponent.getFinCount();
} else if (component instanceof SymmetricComponent) {
aBt += ((SymmetricComponent) component).getComponentPlanformArea();
}
}
}
return (cDFin * aFins + cDBt * aBt)/status.getConfiguration().getReferenceArea();
}
@Override @Override
public void step(SimulationStatus status, double maxTimeStep) throws SimulationException { public void step(SimulationStatus status, double maxTimeStep) throws SimulationException {
@ -33,7 +96,7 @@ public class BasicTumbleStepper extends AbstractSimulationStepper {
// Get total CD // Get total CD
double mach = airSpeed.length() / atmosphere.getMachSpeed(); double mach = airSpeed.length() / atmosphere.getMachSpeed();
double tumbleCD = ((BasicTumbleStatus)status).getCD(); double tumbleCD = getCD();
// Compute drag force // Compute drag force
double dynP = (0.5 * atmosphere.getDensity() * airSpeed.length2()); double dynP = (0.5 * atmosphere.getDensity() * airSpeed.length2());