[test] adds test to verify that splitting fins reproduces the same results

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

@@ -192,27 +192,24 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
 			if (null != calcObj) {
 				// iterate across component instances
 				final ArrayList<InstanceContext> contextList = entry.getValue();
-
 				for(InstanceContext context: contextList ) {
 					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);
+					Coordinate cp_inst = instanceForces.getCP();
+					Coordinate cp_abs = context.transform.transform(cp_inst);
 					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);
 				}
 			}
 		}
 
-		// System.err.println("assemblyForces=" + assemblyForces);
 		return assemblyForces;
 	}
 	

core/src/net/sf/openrocket/util/TestRockets.java

@@ -530,6 +530,24 @@ public class TestRockets {
 		return rocket;
 	}
 	
+	// This function is used for unit, integration tests, DO NOT CHANGE (without updating tests).
+	public static final void splitRocketFins( BodyTube body, FinSet fins, int finCount){
+		// actually remove the fins
+		body.removeChild(fins);
+
+		FinSet template = fins; 
+		template.setFinCount(1);
+		// and manually add in the equivalent:
+		for(int finNumber=0; finNumber<finCount; ++finNumber){
+			final TrapezoidFinSet singleFin = new TrapezoidFinSet(1, 0.05, 0.03, 0.02, 0.05);
+			singleFin.setAngleOffset( finNumber * Math.PI * 2.0 / finCount);
+			singleFin.setThickness( 0.0032);
+			singleFin.setAxialMethod(AxialMethod.BOTTOM);
+			singleFin.setName(String.format("Single Fin #%d", finNumber));
+			body.addChild(singleFin);
+		}
+	}
+
 	// This is an extra stage tacked onto the end of an Estes Alpha III 
 	// http://www.rocketreviews.com/alpha-iii---estes-221256.html
 	// 

core/test/net/sf/openrocket/aerodynamics/BarrowmanCalculatorTest.java

@@ -15,6 +15,7 @@ import net.sf.openrocket.ServicesForTesting;
 import net.sf.openrocket.plugin.PluginModule;
 import net.sf.openrocket.rocketcomponent.AxialStage;
 import net.sf.openrocket.rocketcomponent.BodyTube;
+import net.sf.openrocket.rocketcomponent.FinSet;
 import net.sf.openrocket.rocketcomponent.FlightConfiguration;
 import net.sf.openrocket.rocketcomponent.NoseCone;
 import net.sf.openrocket.rocketcomponent.ParallelStage;
@@ -145,6 +146,31 @@ public class BarrowmanCalculatorTest {
 		}
 	}
 
+	@Test
+	public void testCpSplitTripleFin() {
+		final BarrowmanCalculator calc = new BarrowmanCalculator();
+		final WarningSet warnings = new WarningSet();
+
+		final Rocket rocket = TestRockets.makeEstesAlphaIII();
+		final FlightConfiguration config = rocket.getSelectedConfiguration();
+		final FlightConditions conditions = new FlightConditions(config);
+
+		{
+			final Coordinate wholeRocketCP = calc.getCP(config, conditions, warnings);
+			assertEquals("Split-Fin Rocket CNa value is incorrect:", 26.14693374, wholeRocketCP.weight, EPSILON);
+			assertEquals("Split-Fin Rocket CP x value is incorrect:", 0.22351541, wholeRocketCP.x, EPSILON);
+		}{
+			final BodyTube body = (BodyTube)rocket.getChild(0).getChild(1);
+			final FinSet fins = (FinSet)body.getChild(0);
+			fins.setAngleOffset(0);
+			TestRockets.splitRocketFins(body, fins, 3);
+			
+			final Coordinate wholeRocketCP = calc.getCP(config, conditions, warnings);
+			assertEquals("Split-Fin Rocket CNa value is incorrect:", 26.14693374, wholeRocketCP.weight, EPSILON);
+			assertEquals("Split-Fin Rocket CP x value is incorrect:", 0.22351541, wholeRocketCP.x, EPSILON);
+		}
+	}
+
 	// test rocket with endplates on fins.  Comments tracing
 	// calculation of CP are in TestRockets.makeEndPlateRocket().
 	@Test