Merge pull request #1677 from SiboVG/issue-1676

[#1676] Treat zero-length SymmetricComponent as tube/disk

core/src/net/sf/openrocket/aerodynamics/BarrowmanCalculator.java

@@ -634,14 +634,19 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
 			// base drag calculation
 			if (c instanceof SymmetricComponent) {
 				SymmetricComponent s = (SymmetricComponent) c;
-				
+				double foreRadius = s.getForeRadius();
+				double aftRadius = s.getAftRadius();
+				// If length is zero, the component is a disk, i.e. a zero-length tube, so match the fore and aft diameter
+				if (s.getLength() == 0) {
+					foreRadius = Math.max(foreRadius, aftRadius);
+				}
 				double radius = 0;
 				final SymmetricComponent prevComponent = s.getPreviousSymmetricComponent();
 				if (prevComponent != null && configuration.isComponentActive(prevComponent))
 					radius = prevComponent.getAftRadius();
 					
-				if (radius < s.getForeRadius()) {
+				if (radius < foreRadius) {
-					double area = Math.PI * (pow2(s.getForeRadius()) - pow2(radius));
+					double area = Math.PI * (pow2(foreRadius) - pow2(radius));
 					cd = stagnation * area / conditions.getRefArea();
 					total += instanceCount * cd;
 						
@@ -685,6 +690,13 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
 			}
 
 			SymmetricComponent s = (SymmetricComponent) c;
+			double foreRadius = s.getForeRadius();
+			double aftRadius = s.getAftRadius();
+			// If length is zero, the component is a disk, i.e. a zero-length tube, so match the fore and aft diameter
+			if (s.getLength() == 0) {
+				final double componentMaxR = Math.max(foreRadius, aftRadius);
+				foreRadius = aftRadius = componentMaxR;
+			}
 
 			int instanceCount = entry.getValue().size();
 			
@@ -701,8 +713,8 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
 				radius = prevComponent.getAftRadius();
 			}
 			
-			if (radius > s.getForeRadius()) {
+			if (radius > foreRadius) {
-				double area = Math.PI * (pow2(radius) - pow2(s.getForeRadius()));
+				double area = Math.PI * (pow2(radius) - pow2(foreRadius));
 				double cd = base * area / conditions.getRefArea();
 				total += instanceCount * cd;
 				if ((forceMap != null) && (prevComponent != null)) {
@@ -712,10 +724,10 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
 				
 			// if I'm the last component, set my base CD
 			// note:  the iterator *should* serve up the next component.... buuuut ....
-			//        this code has is tested, and there's no compelling reason to change.
+			//        this code is tested, and there's no compelling reason to change.
 			final SymmetricComponent n = s.getNextSymmetricComponent();
 			if ((n == null) || !configuration.isStageActive(n.getStageNumber())) {
-				double area = Math.PI * pow2(s.getAftRadius());
+				double area = Math.PI * pow2(aftRadius);
 				double cd = base * area / conditions.getRefArea();
 				total += instanceCount * cd;
 				if (forceMap != null) {

core/src/net/sf/openrocket/aerodynamics/barrowman/SymmetricComponentCalc.java

@@ -56,8 +56,13 @@ public class SymmetricComponentCalc extends RocketComponentCalc {
 		SymmetricComponent component = (SymmetricComponent) c;
 
 		length = component.getLength();
+		if (length > 0) {
 			foreRadius = component.getForeRadius();
 			aftRadius = component.getAftRadius();
+		} else {	// If length is zero, the component is a disk, i.e. a zero-length tube, so match the fore and aft diameter
+			final double componentMaxR = Math.max(component.getForeRadius(), component.getAftRadius());
+			foreRadius = aftRadius = componentMaxR;
+		}
 		
 		fineness = length / (2 * Math.abs(aftRadius - foreRadius));
 		fullVolume = component.getFullVolume();

core/src/net/sf/openrocket/rocketcomponent/SymmetricComponent.java

@@ -312,13 +312,15 @@ public abstract class SymmetricComponent extends BodyComponent implements BoxBou
 		double x, r1, r2;
 		double cgx;
 
-		// Check length > 0
-		if (length <= 0) {
 		wetArea = 0;
 		planArea = 0;
 		planCenter = 0;
+		fullVolume = 0;
 		volume = 0;
 		cg = Coordinate.NUL;
+
+		// Check length > 0
+		if (length <= 0) {
 			return;
 		}
 		
@@ -329,11 +331,6 @@ public abstract class SymmetricComponent extends BodyComponent implements BoxBou
 		final double pi3 = Math.PI / 3.0;
 		r1 = getRadius(0);
 		x = 0;
-		wetArea = 0;
-		planArea = 0;
-		planCenter = 0;
-		fullVolume = 0;
-		volume = 0;
 		cgx = 0;
 		
 		for (int n = 1; n <= DIVISIONS; n++) {
@@ -423,14 +420,17 @@ public abstract class SymmetricComponent extends BodyComponent implements BoxBou
 	private void integrateInertiaVolume() {
 		double x, r1, r2;
 
+		longitudinalInertia = 0;
+		rotationalInertia = 0;
+
+		if (length <= 0) return;
+
 		final double l = length / DIVISIONS;
 		final double pil = Math.PI * l; // PI * l
 		final double pil3 = Math.PI * l / 3; // PI * l/3
 		
 		r1 = getRadius(0);
 		x = 0;
-		longitudinalInertia = 0;
-		rotationalInertia = 0;
 		
 		double vol = 0;
 		
@@ -490,15 +490,16 @@ public abstract class SymmetricComponent extends BodyComponent implements BoxBou
 	private void integrateInertiaSurface() {
 		double x, r1, r2;
 
+		longitudinalInertia = 0;
+		rotationalInertia = 0;
+
+		if (length <= 0) return;
+
 		final double l = length / DIVISIONS;
 		
 		r1 = getRadius(0);
-		//System.out.println(r1);
 		x = 0;
 		
-		longitudinalInertia = 0;
-		rotationalInertia = 0;
-		
 		double surface = 0;
 		
 		for (int n = 1; n <= DIVISIONS; n++) {

core/src/net/sf/openrocket/rocketcomponent/Transition.java

@@ -479,7 +479,7 @@ public class Transition extends SymmetricComponent implements InsideColorCompone
 	public double getRadius(double x) {
 		if ( x < 0 )
 			return getForeRadius();
-		if ( x > length)
+		if ( x >= length)
 			return getAftRadius();
 
 		double r1 = getForeRadius();