Editing Thrust reversal (section)

====Internal types====
[[File:VC10 Aircraft at an Airfield in the Middle East MOD 45150451.jpg|thumb|Clamshell outlet grating open (outboard engine) on a [[Rolls-Royce Conway]] turbofan of a [[Royal Air Force]] [[Vickers VC10|Vickers VC-10]] [[Aerial refueling|tanker]]]]

Internal thrust reversers use deflector doors inside the engine shroud to redirect airflow through openings in the side of the nacelle.<ref name="Airplane handbook2011"/> In [[turbojet]] and mixed-flow bypass turbofan engines, one type uses [[pneumatic]]ally operated ''clamshell'' deflectors to redirect engine exhaust.<ref name=Purdue /><ref name="MacIsaacLangton2011 Propulsion" /> The reverser ducts may be fitted with cascade vanes to further redirect the airflow forward.<ref name="MacIsaacLangton2011 Propulsion" />
[[File:Airbus A330 (Aeroflot) Sheremetyevo (5369213039).jpg|thumb|Clamshell-type thrust reversers deployed on the [[Rolls-Royce Trent 700]] engine of an [[Airbus A330]]. The redirected thrust blows water from the wet surface, making the air flow observable.]]
[[File:PH-BVC KLM (3701878334).jpg|thumb|Cold-stream type thrust reverser being deployed on a Boeing 777-300]]
In contrast to the two types used on turbojet and low-bypass turbofan engines, many high-bypass turbofan engines use a ''cold-stream'' reverser. This design places the deflector doors in the [[bypass duct]] to redirect only the portion of the airflow from the engine's fan section that bypasses the [[combustion chamber]].<ref name="Soares2011 Gas turbines" /> Engines such as the A320 and A340 versions of the [[CFM International CFM56|CFM56]] direct the airflow forward with a ''pivoting-door'' reverser similar to the internal clamshell used in some turbojets.<ref>{{cite book |last = Linke-Diesinger |first = Andreas |title = Systems of Commercial Turbofan Engines: An Introduction to Systems Functions |publisher = Springer Berlin Heidelberg |year = 2008 |chapter = Chapter 8: Thrust Reverser Systems |doi = 10.1007/978-3-540-73619-6_8 |isbn = 978-3-540-73618-9}}</ref> ''Cascade'' reversers use a vane cascade that is uncovered by a sleeve around the perimeter of the engine [[nacelle]] that slides aft by means of an air motor. During normal operation, the reverse thrust vanes are blocked. On selection, the system folds the doors to block off the cold stream final [[nozzle]] and redirect this airflow to the cascade vanes.<ref name=Purdue /> 

In cold-stream reversers, the exhaust from the combustion chamber continues to generate forward thrust, making this design less effective.<ref name="Airplane handbook2011" /><ref name=Purdue /> It can also redirect core exhaust flow if equipped with a hot stream spoiler.<ref name="MacIsaacLangton2011 Propulsion" /> The cold stream cascade system is known for structural integrity, reliability and versatility, but can be heavy and difficult to integrate into nacelles housing large engines.<ref name="AsburyYetter2000 NASA" />