diff --git a/core/src/net/sf/openrocket/rocketcomponent/MassObject.java b/core/src/net/sf/openrocket/rocketcomponent/MassObject.java
index 2058d1b72..1522fde04 100644
--- a/core/src/net/sf/openrocket/rocketcomponent/MassObject.java
+++ b/core/src/net/sf/openrocket/rocketcomponent/MassObject.java
@@ -65,6 +65,25 @@ public abstract class MassObject extends InternalComponent {
 		return length;
 	}
 
+	/**
+	 * Set the length, ignoring the auto radius setting.
+	 * @param length new length
+	 */
+	public void setLengthNoAuto(double length) {
+		for (RocketComponent listener : configListeners) {
+			if (listener instanceof MassObject) {
+				((MassObject) listener).setLengthNoAuto(length);
+			}
+		}
+
+		length = Math.max(length, 0);
+		if (MathUtil.equals(this.length, length)) {
+			return;
+		}
+		this.length = length;
+		fireComponentChangeEvent(ComponentChangeEvent.MASS_CHANGE);
+	}
+
 	public void setLength(double length) {
 		for (RocketComponent listener : configListeners) {
 			if (listener instanceof MassObject) {
diff --git a/swing/src/net/sf/openrocket/gui/dialogs/ScaleDialog.java b/swing/src/net/sf/openrocket/gui/dialogs/ScaleDialog.java
index 407ba5109..4027ed599 100644
--- a/swing/src/net/sf/openrocket/gui/dialogs/ScaleDialog.java
+++ b/swing/src/net/sf/openrocket/gui/dialogs/ScaleDialog.java
@@ -126,8 +126,11 @@ public class ScaleDialog extends JDialog {
 		SCALERS_NO_OFFSET.put(FreeformFinSet.class, list);
 		
 		// MassObject
-		addScaler(MassObject.class, "Length", SCALERS_NO_OFFSET);
-		addScaler(MassObject.class, "Radius", SCALERS_NO_OFFSET);
+		list = new ArrayList<>(1);
+		list.add(new MassObjectScaler());
+		SCALERS_NO_OFFSET.put(MassObject.class, list);
+		//addScaler(MassObject.class, "LengthNoAuto", SCALERS_NO_OFFSET);
+		addScaler(MassObject.class, "Radius", "isRadiusAutomatic", SCALERS_NO_OFFSET);
 		addScaler(MassObject.class, "RadialPosition", SCALERS_OFFSET);
 		
 		// MassComponent
@@ -703,6 +706,25 @@ public class ScaleDialog extends JDialog {
 		}
 		
 	}
+
+	private static class MassObjectScaler implements Scaler {
+		@Override
+		public void scale(RocketComponent component, double multiplier, boolean scaleMass) {
+			if (scaleMass) {
+				MassObject c = (MassObject) component;
+				if (c.isRadiusAutomatic()) {
+					double volume = Math.PI * Math.pow(c.getRadiusNoAuto(), 2) * c.getLengthNoAuto();
+					double scaledVolume = volume * MathUtil.pow3(multiplier);
+					c.setRadius(c.getRadiusNoAuto() * multiplier);
+					c.setLengthNoAuto(scaledVolume / (Math.PI * Math.pow(c.getRadiusNoAuto(), 2)));
+					c.setRadiusAutomatic(true);
+				} else {
+					c.setLength(c.getLength() * multiplier);
+				}
+			}
+		}
+
+	}
 	
 	private static class FreeformFinSetScaler implements Scaler {