diff --git a/core/src/net/sf/openrocket/optimization/rocketoptimization/parameters/SimulationBasedParameter.java b/core/src/net/sf/openrocket/optimization/rocketoptimization/parameters/SimulationBasedParameter.java
index 5d0b455bb..e36ac7d04 100644
--- a/core/src/net/sf/openrocket/optimization/rocketoptimization/parameters/SimulationBasedParameter.java
+++ b/core/src/net/sf/openrocket/optimization/rocketoptimization/parameters/SimulationBasedParameter.java
@@ -9,11 +9,9 @@ import net.sf.openrocket.document.Simulation;
 import net.sf.openrocket.optimization.general.OptimizationException;
 import net.sf.openrocket.optimization.rocketoptimization.OptimizableParameter;
 import net.sf.openrocket.simulation.FlightData;
-import net.sf.openrocket.simulation.exception.MotorIgnitionException;
 import net.sf.openrocket.simulation.exception.SimulationCalculationException;
 import net.sf.openrocket.simulation.exception.SimulationCancelledException;
 import net.sf.openrocket.simulation.exception.SimulationException;
-import net.sf.openrocket.simulation.exception.SimulationLaunchException;
 import net.sf.openrocket.simulation.listeners.SimulationListener;
 import net.sf.openrocket.simulation.listeners.system.InterruptListener;
 
@@ -40,12 +38,6 @@ public abstract class SimulationBasedParameter implements OptimizableParameter {
 			double value = getResultValue(simulation.getSimulatedData());
 			log.debug("Parameter '" + getName() + " was " + value);
 			return value;
-		} catch (MotorIgnitionException e) {
-			// A problem with motor ignition will cause optimization to fail
-			throw new OptimizationException(e);
-		} catch (SimulationLaunchException e) {
-			// Other launch exceptions result in illegal value
-			return Double.NaN;
 		} catch (SimulationCalculationException e) {
 			// Calculation errors result in illegal value
 			return Double.NaN;
diff --git a/core/src/net/sf/openrocket/simulation/BasicEventSimulationEngine.java b/core/src/net/sf/openrocket/simulation/BasicEventSimulationEngine.java
index 18aff00bb..098c6735b 100644
--- a/core/src/net/sf/openrocket/simulation/BasicEventSimulationEngine.java
+++ b/core/src/net/sf/openrocket/simulation/BasicEventSimulationEngine.java
@@ -21,9 +21,8 @@ import net.sf.openrocket.rocketcomponent.MotorMount;
 import net.sf.openrocket.rocketcomponent.RecoveryDevice;
 import net.sf.openrocket.rocketcomponent.RocketComponent;
 import net.sf.openrocket.rocketcomponent.StageSeparationConfiguration;
-import net.sf.openrocket.simulation.exception.MotorIgnitionException;
+import net.sf.openrocket.simulation.exception.SimulationCalculationException;
 import net.sf.openrocket.simulation.exception.SimulationException;
-import net.sf.openrocket.simulation.exception.SimulationLaunchException;
 import net.sf.openrocket.simulation.listeners.SimulationListenerHelper;
 import net.sf.openrocket.simulation.listeners.system.OptimumCoastListener;
 import net.sf.openrocket.startup.Application;
@@ -709,7 +708,7 @@ public class BasicEventSimulationEngine implements SimulationEngine {
 					" rocketOrientationQuaternion=" + currentStatus.getRocketOrientationQuaternion() +
 					" rocketRotationVelocity=" + currentStatus.getRocketRotationVelocity() +
 					" effectiveLaunchRodLength=" + currentStatus.getEffectiveLaunchRodLength());
-			throw new SimulationException(trans.get("BasicEventSimulationEngine.error.NaNResult"));
+			throw new SimulationCalculationException(trans.get("BasicEventSimulationEngine.error.NaNResult"));
 		}
 	}
 	
diff --git a/core/src/net/sf/openrocket/simulation/exception/MotorIgnitionException.java b/core/src/net/sf/openrocket/simulation/exception/MotorIgnitionException.java
deleted file mode 100644
index fd9e60ac9..000000000
--- a/core/src/net/sf/openrocket/simulation/exception/MotorIgnitionException.java
+++ /dev/null
@@ -1,19 +0,0 @@
-package net.sf.openrocket.simulation.exception;
-
-/**
- * An exception signifying that the simulation failed because no motors were
- * defined or ignited in the rocket.
- * 
- * @author Sampo Niskanen <sampo.niskanen@iki.fi>
- */
-public class MotorIgnitionException extends SimulationLaunchException {
-	
-	public MotorIgnitionException(String message) {
-		super(message);
-	}
-	
-	public MotorIgnitionException(String message, Throwable cause) {
-		super(message, cause);
-	}
-	
-}
diff --git a/core/src/net/sf/openrocket/simulation/exception/SimulationLaunchException.java b/core/src/net/sf/openrocket/simulation/exception/SimulationLaunchException.java
deleted file mode 100644
index df9f3862d..000000000
--- a/core/src/net/sf/openrocket/simulation/exception/SimulationLaunchException.java
+++ /dev/null
@@ -1,19 +0,0 @@
-package net.sf.openrocket.simulation.exception;
-
-/**
- * An exception signifying that a problem occurred at launch, for example
- * that no motors were defined or no motors ignited.
- * 
- * @author Sampo Niskanen <sampo.niskanen@iki.fi>
- */
-public class SimulationLaunchException extends SimulationException {
-	
-	public SimulationLaunchException(String message) {
-		super(message);
-	}
-	
-	public SimulationLaunchException(String message, Throwable cause) {
-		super(message, cause);
-	}
-	
-}
diff --git a/core/test/net/sf/openrocket/simulation/DisableStageTest.java b/core/test/net/sf/openrocket/simulation/DisableStageTest.java
index d0eb1e8d4..b10aab5bc 100644
--- a/core/test/net/sf/openrocket/simulation/DisableStageTest.java
+++ b/core/test/net/sf/openrocket/simulation/DisableStageTest.java
@@ -4,7 +4,6 @@ import net.sf.openrocket.document.Simulation;
 import net.sf.openrocket.rocketcomponent.FlightConfiguration;
 import net.sf.openrocket.rocketcomponent.FlightConfigurationId;
 import net.sf.openrocket.rocketcomponent.Rocket;
-import net.sf.openrocket.simulation.exception.MotorIgnitionException;
 import net.sf.openrocket.simulation.exception.SimulationException;
 import net.sf.openrocket.util.BaseTestCase.BaseTestCase;
 import net.sf.openrocket.util.TestRockets;
@@ -34,6 +33,7 @@ public class DisableStageTest extends BaseTestCase {
         simDisabled.getOptions().setTimeStep(0.05);
 
         // Since there are no stages, the simulation should throw an exception.
+		// Needs fixing for SimulationAbort
         try {
             simDisabled.simulate();
         } catch (SimulationException e) {
diff --git a/swing/src/net/sf/openrocket/gui/simulation/SimulationRunDialog.java b/swing/src/net/sf/openrocket/gui/simulation/SimulationRunDialog.java
index 2ff3c7101..1d455f3f0 100644
--- a/swing/src/net/sf/openrocket/gui/simulation/SimulationRunDialog.java
+++ b/swing/src/net/sf/openrocket/gui/simulation/SimulationRunDialog.java
@@ -45,7 +45,6 @@ import net.sf.openrocket.simulation.customexpression.CustomExpression;
 import net.sf.openrocket.simulation.customexpression.CustomExpressionSimulationListener;
 import net.sf.openrocket.simulation.exception.SimulationCancelledException;
 import net.sf.openrocket.simulation.exception.SimulationException;
-import net.sf.openrocket.simulation.exception.SimulationLaunchException;
 import net.sf.openrocket.simulation.listeners.AbstractSimulationListener;
 import net.sf.openrocket.simulation.listeners.SimulationListener;
 import net.sf.openrocket.startup.Application;
@@ -425,15 +424,7 @@ public class SimulationRunDialog extends JDialog {
 			}
 
 			// Analyze the exception type
-			if (t instanceof SimulationLaunchException) {
-
-				DetailDialog.showDetailedMessageDialog(SimulationRunDialog.this,
-						new Object[] {
-								//// Unable to simulate:
-								trans.get("SimuRunDlg.msg.Unabletosim"), t.getMessage() },
-						null, simulation.getName(), JOptionPane.ERROR_MESSAGE);
-
-			} else if (t instanceof SimulationException) {
+			if (t instanceof SimulationException) {
 				String title = simulation.getName();
 				FlightDataBranch dataBranch = ((SimulationException) t).getFlightDataBranch();