From 1011f2df944dbfe3e82016ea0a3a0f0954c1ca9b Mon Sep 17 00:00:00 2001
From: JoePfeiffer <joseph@pfeifferfamily.net>
Date: Sun, 26 Feb 2023 09:41:55 -0700
Subject: [PATCH] Don't let fins with zero area cause NaN exceptions.

---
 .../aerodynamics/barrowman/FinSetCalc.java           | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/core/src/net/sf/openrocket/aerodynamics/barrowman/FinSetCalc.java b/core/src/net/sf/openrocket/aerodynamics/barrowman/FinSetCalc.java
index f7da050a1..326c73a0d 100644
--- a/core/src/net/sf/openrocket/aerodynamics/barrowman/FinSetCalc.java
+++ b/core/src/net/sf/openrocket/aerodynamics/barrowman/FinSetCalc.java
@@ -86,7 +86,7 @@ public class FinSetCalc extends RocketComponentCalc {
 		
 		warnings.addAll(geometryWarnings);
 		
-		if (span < 0.001) {
+		if (finArea < MathUtil.EPSILON) {
 			forces.setCm(0);
 			forces.setCN(0);
 			forces.setCNa(0);
@@ -618,6 +618,11 @@ public class FinSetCalc extends RocketComponentCalc {
 
 	@Override
 	public double calculateFrictionCD(FlightConditions conditions, double componentCf, WarningSet warnings) {
+		// a fin with 0 area contributes no drag
+		if (finArea < MathUtil.EPSILON) {
+			return 0.0;
+		}
+		
 		double cd = componentCf * (1 + 2 * thickness / macLength) * 2 * finArea / conditions.getRefArea();
 		return cd;
 	}
@@ -626,6 +631,11 @@ public class FinSetCalc extends RocketComponentCalc {
 	public double calculatePressureCD(FlightConditions conditions,
 									  double stagnationCD, double baseCD, WarningSet warnings) {
 		
+		// a fin with 0 area contributes no drag
+		if (finArea < MathUtil.EPSILON) {
+			return 0.0;
+		}
+
 		double mach = conditions.getMach();
 		double cd = 0;