Expert: Paul Soderman - 12/30/2000

Question
Please could you explain how reverse thrust actually slows a jet aircraft down when it's deployed on landing?I understand that the thrust is directed against some sort of deployable cowling but that's as far as it goes....! Thank you!

Answer
You are right.  Heavy, curved cowlings deploy in the jet exhaust such that the jet flow is redirected forward in the direction of airplane motion.  Hence, the jet thrust, which is always opposite to the direction of jet flow, is directed aft and the airplane slows down.

Another way of looking at it is to imagine the cowlings deployed in the jet exhaust, which develop a large pressure caused by the redirection of the jet.  The resultant of the pressure is opposite the direction of aircraft motion and slows the airplane.