diff --git a/Nasal/bo105.nas b/Nasal/bo105.nas
deleted file mode 100644
index 4975b2ab1..000000000
--- a/Nasal/bo105.nas
+++ /dev/null
@@ -1,41 +0,0 @@
-# $Id$
-#print("Loading bo105.nas");
-if (streq(getprop("/sim/aero"), "bo105")) {
-       print(
-               "Additional key bindings for the bo105 helicopter:\n\n",
-               "\tShift-C ... open/close rear door"
-       );
-}
-
-rearpos = "/controls/doors/rear";
-rearstep = "/controls/doors/rear-state";
-setprop(rearstep, 0);
-
-reardoor = func {
-	pos = getprop(rearpos);
-	step = getprop(rearstep);
-	if (pos == 0 or step < 0) {
-		setprop(rearstep, 0.02);
-	} elsif (pos == 1 or step > 0) {
-		setprop(rearstep, -0.02);
-	}
-	settimer(MoveDoor, 0.05);
-}
-
-MoveDoor = func {
-	pos = getprop(rearpos);
-	step = getprop(rearstep);
-	if (pos + step >= 0 and pos + step <= 1) {
-		setprop(rearpos, pos + step);
-		settimer(MoveDoor, 0.05);
-	} else {
-		if (step < 0) {
-			setprop(rearpos, 0);
-		} elsif (step > 0) {
-			setprop(rearpos, 1);
-		}
-		setprop(rearstep, 0);
-	}
-}
-
-#print("Finished loading bo105.nas");
diff --git a/Nasal/globals.nas b/Nasal/globals.nas
index 7afbe86ce..e4a71e865 100644
--- a/Nasal/globals.nas
+++ b/Nasal/globals.nas
@@ -31,3 +31,33 @@ fgcommand = func {
 # props.Node object.
 #
 cmdarg = func { props.wrapNode(_cmdarg()) }
+
+##
+# Utility.  Does what it you think it does.
+#
+abs = func { if(arg[0] < 0) { -arg[0] } else { arg[0] } }
+
+##
+# Convenience wrapper for the _interpolate function.  Takes a
+# single string or props.Node object in arg[0] indicating a target
+# property, and a variable-length list of time/value pairs.  Example:
+#
+#  interpolate("/animations/radar/angle",
+#              180, 1, 360, 1, 0, 0,
+#              180, 1, 360, 1, 0, 0,
+#              180, 1, 360, 1, 0, 0,
+#              180, 1, 360, 1, 0, 0,
+#              180, 1, 360, 1, 0, 0,
+#              180, 1, 360, 1, 0, 0,
+#              180, 1, 360, 1, 0, 0,
+#              180, 1, 360, 1, 0, 0);
+#
+# This will swing the "radar dish" smoothly through 8 revolutions over
+# 16 seconds.  Note the use of zero-time interpolation between 360 and
+# 0 to wrap the interpolated value properly.
+#
+interpolate = func {
+    if(isa(arg[0], props.Node)) { arg[0] = arg[0]._g; }
+    elsif(typeof(arg[0]) != "scalar") { return; }
+    _interpolate(arg[0], subvec(arg, 1));
+}