From dd3bda8d7e3a7084a649c2e2b68e8a94ab4663ec Mon Sep 17 00:00:00 2001
From: JoePfeiffer <joseph@pfeifferfamily.net>
Date: Fri, 20 Mar 2020 14:53:39 -0600
Subject: [PATCH] Corrected calculatePressureDrag() to iterate through all
 instances. Note this required modifying the function to explicitly get the
 radius of the forward symmetric component rather than simply iterating and
 assuming components would appear in order (as was the case with iterating
 through getActiveComponents()). The getPreviousSymmetricComponent() method
 contains a warning that it doesn't account for external pods, so this will
 probably need to be revisited and that method modified.

---
 .../aerodynamics/BarrowmanCalculator.java        | 16 +++++++++-------
 .../rocketcomponent/SymmetricComponent.java      |  2 +-
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/core/src/net/sf/openrocket/aerodynamics/BarrowmanCalculator.java b/core/src/net/sf/openrocket/aerodynamics/BarrowmanCalculator.java
index 6cbf1ca04..880db8151 100644
--- a/core/src/net/sf/openrocket/aerodynamics/BarrowmanCalculator.java
+++ b/core/src/net/sf/openrocket/aerodynamics/BarrowmanCalculator.java
@@ -506,7 +506,6 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
 			Map<RocketComponent, AerodynamicForces> map, WarningSet warnings) {
 		
 		double stagnation, base, total;
-		double radius = 0;
 		
 		if (calcMap == null)
 			buildCalcMap(configuration);
@@ -524,33 +523,36 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
 			// iterate across component instances
 			final ArrayList<InstanceContext> contextList = entry.getValue();
 			for(InstanceContext context: contextList ) {
-				
+
 				// Pressure fore drag
 				double cd = calcMap.get(c).calculatePressureDragForce(conditions, stagnation, base,
 																	  warnings);
 				total += cd;
-				
+
 				if (map != null) {
 					map.get(c).setPressureCD(cd);
 				}
 				
 				if(c.isCDOverridden()) continue;					
 				
-				
 				// Stagnation drag
 				if (c instanceof SymmetricComponent) {
 					SymmetricComponent s = (SymmetricComponent) c;
+
+					double radius = 0;
+					final SymmetricComponent prevComponent = s.getPreviousSymmetricComponent();
+					if (prevComponent != null)
+						radius = prevComponent.getAftRadius();
 					
 					if (radius < s.getForeRadius()) {
 						double area = Math.PI * (pow2(s.getForeRadius()) - pow2(radius));
 						cd = stagnation * area / conditions.getRefArea();
 						total += cd;
+						
 						if (map != null) {
 							map.get(c).setPressureCD(map.get(c).getPressureCD() + cd);
 						}
 					}
-					
-					radius = s.getAftRadius();
 				}
 			}
 		}
@@ -558,7 +560,7 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
 		return total;
 	}
 	
-	
+
 	/**
 	 * Calculation of drag coefficient due to base
 	 * 
diff --git a/core/src/net/sf/openrocket/rocketcomponent/SymmetricComponent.java b/core/src/net/sf/openrocket/rocketcomponent/SymmetricComponent.java
index a530bfe94..35957c459 100644
--- a/core/src/net/sf/openrocket/rocketcomponent/SymmetricComponent.java
+++ b/core/src/net/sf/openrocket/rocketcomponent/SymmetricComponent.java
@@ -566,7 +566,7 @@ public abstract class SymmetricComponent extends BodyComponent implements Radial
 	 * 
 	 * @return	the previous SymmetricComponent, or null.
 	 */
-	protected final SymmetricComponent getPreviousSymmetricComponent() {
+	public final SymmetricComponent getPreviousSymmetricComponent() {
 		RocketComponent c;
 		for (c = this.getPreviousComponent(); c != null; c = c.getPreviousComponent()) {
 			if (c instanceof SymmetricComponent) {