diff --git a/engine.lisp b/engine.lisp
index fa8a97c..6ad801e 100644
--- a/engine.lisp
+++ b/engine.lisp
@@ -43,6 +43,9 @@
     ((32 64 2) (32 132 2) (32 164 2))
     ((0 255 2) (0 255 2) (64 255 2))))
 
+;; jet shooting up
+(defparameter *jet-vertices* 
+  '((0 0 -0.2) (-0.2 0 0.2) (0.2 0 0.2) (0 (0 0.4 1) 0)))
 
 (defmethod draw ((object engine-object) time) 
   (if (< (- time (start-time object)) (activation-time object)) ;; hack since times are in templates!!!
diff --git a/flight-sim.lisp b/flight-sim.lisp
index 4237cd9..58d9954 100644
--- a/flight-sim.lisp
+++ b/flight-sim.lisp
@@ -189,7 +189,19 @@
 			      :force (make-instance 'force :newtons 10000 :direction (vector 0 0 1))
 			      
 			      :body (make-instance 'body
-						   :coords (vector 0 0 1.5))))))
+						   :coords (vector 0 0 1.5)))
+	       ; yaw (starboard (right) positive)
+	       :pos-yaw 
+	       (make-instance 'engine-object
+			      :activation-time 2
+			      :model (make-instance 'engine-model
+						    :template-vertices *jet-vertices*
+						    :template-colors *thruster-colors*
+						    :faces (make-2d-array 4 3 '((0 1 3) (0 2 1) (0 3 2) (1 2 3)))
+						    :face-colors (make-2d-array 4 3 '((0 1 3) (0 2 1) (0 3 2) (1 2 3))))
+			      :body (make-instance 'body
+						   :coords (vector 
+)))
 			      ;:engines (list :engines (list :thrust 
 				;		       (make-instance 'engine-object 
 				;				      :motion (make-instance 'motion :coords (vector 0 0.5 3.0))
diff --git a/math.lisp b/math.lisp
index 428fd9e..60d4442 100644
--- a/math.lisp
+++ b/math.lisp
@@ -17,7 +17,9 @@
 
 ;; function to determine value lying on start to end taking time duration at now
 (defun converge (start end duration now)
-  (float (+ start (* (- end start) (if (eql now 0.0) 0.0 (/ (min now duration) duration))))))
+  (if (> now duration) 
+      end
+      (float (+ start (* (- end start) (if (eql now 0.0) 0.0 (/ (min now duration) duration)))))))
 
 
 ;; returns a real lisp 2d array