diff --git a/core/test/net/sf/openrocket/rocketcomponent/MassObjectTest.java b/core/test/net/sf/openrocket/rocketcomponent/MassObjectTest.java
new file mode 100644
index 000000000..a7e18ea75
--- /dev/null
+++ b/core/test/net/sf/openrocket/rocketcomponent/MassObjectTest.java
@@ -0,0 +1,86 @@
+package net.sf.openrocket.rocketcomponent;
+
+import net.sf.openrocket.util.BaseTestCase.BaseTestCase;
+import net.sf.openrocket.util.MathUtil;
+import org.junit.Test;
+import org.junit.Assert;
+
+public class MassObjectTest extends BaseTestCase {
+    @Test
+    public void testAutoRadius() {
+        MassObject sc = new ShockCord();
+        MassObject mc = new MassComponent();
+        MassObject pc = new Parachute();
+        MassObject st = new Streamer();
+        MassObject[] massObjects = {sc, mc, pc, st};
+
+        for (MassObject mo : massObjects) {
+            // Test no auto
+            mo.setRadiusAutomatic(false);
+            mo.setRadius(0.1);
+            mo.setLength(0.1);
+            Assert.assertEquals(String.format(" No auto %s incorrect radius", mo.getClass().getName()),
+                    0.1, mo.getRadius(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" No auto %s incorrect no auto radius", mo.getClass().getName()),
+                    0.1, mo.getRadiusNoAuto(),MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" No auto %s incorrect length", mo.getClass().getName()),
+                    0.1, mo.getLength(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" No auto %s incorrect no auto length", mo.getClass().getName()),
+                    0.1, mo.getLengthNoAuto(), MathUtil.EPSILON);
+
+            mo.setLengthNoAuto(0.1);
+            Assert.assertEquals(String.format(" No auto 2 %s incorrect length", mo.getClass().getName()),
+                    0.1, mo.getLength(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" No auto 2 %s incorrect no auto length", mo.getClass().getName()),
+                    0.1, mo.getLengthNoAuto(), MathUtil.EPSILON);
+
+            // Test auto
+            BodyTube parent = new BodyTube();
+            parent.setOuterRadius(0.05);
+            parent.setInnerRadius(0.05);
+            parent.addChild(mo);
+            mo.setRadiusAutomatic(true);
+            Assert.assertEquals(String.format(" Auto 1 %s incorrect radius", mo.getClass().getName()),
+                    0.05, mo.getRadius(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 1 %s incorrect no auto radius", mo.getClass().getName()),
+                    0.1, mo.getRadiusNoAuto(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 1 %s incorrect length", mo.getClass().getName()),
+                    0.4, mo.getLength(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 1 %s incorrect no auto length", mo.getClass().getName()),
+                    0.1, mo.getLengthNoAuto(), MathUtil.EPSILON);
+
+            parent.setOuterRadius(0.1);
+            parent.setInnerRadius(0.1);
+            Assert.assertEquals(String.format(" Auto 2 %s incorrect radius", mo.getClass().getName()),
+                    0.1, mo.getRadius(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 2 %s incorrect no auto radius", mo.getClass().getName()),
+                    0.1, mo.getRadiusNoAuto(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 2 %s incorrect length", mo.getClass().getName()),
+                    0.1, mo.getLength(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 2 %s incorrect no auto length", mo.getClass().getName()),
+                    0.1, mo.getLengthNoAuto(), MathUtil.EPSILON);
+
+            parent.setOuterRadius(0.075);
+            parent.setInnerRadius(0.075);
+            mo.setLength(0.075);
+            Assert.assertEquals(String.format(" Auto 3 %s incorrect radius", mo.getClass().getName()),
+                    0.075, mo.getRadius(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 3 %s incorrect no auto radius", mo.getClass().getName()),
+                    0.1, mo.getRadiusNoAuto(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 3 %s incorrect length", mo.getClass().getName()),
+                    0.075, mo.getLength(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 3 %s incorrect no auto length", mo.getClass().getName()),
+                    0.0422, mo.getLengthNoAuto(), 0.001);
+
+            mo.setLengthNoAuto(0.05);
+            Assert.assertEquals(String.format(" Auto 4 %s incorrect radius", mo.getClass().getName()),
+                    0.075, mo.getRadius(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 4 %s incorrect no auto radius", mo.getClass().getName()),
+                    0.1, mo.getRadiusNoAuto(), MathUtil.EPSILON);
+            Assert.assertEquals(String.format(" Auto 4 %s incorrect length", mo.getClass().getName()),
+                    0.0889, mo.getLength(), 0.001);
+            Assert.assertEquals(String.format(" Auto 4 %s incorrect no auto length", mo.getClass().getName()),
+                    0.05, mo.getLengthNoAuto(), MathUtil.EPSILON);
+        }
+    }
+}