Propilot83 From United States of America, joined Jan 2001, 545 posts, RR: 0 Posted (4 years 1 month 3 weeks 4 days 13 hours ago) and read 2183 times:
I had a question for anyone who is a commercial airline pilot. My question is "do the engine blades inside of the engines turn counter clockwise during reverse thrust at touchdown? and "during thrust reversal, where does the air intake flow through the engine or does air flow into the engine during thrust reversal? I understand that the engine exhausts are directed to blow forward instead of aft during thrust reversal, however during thrust reversal does the engine suck in any air or not? Thanks!
Vikkyvik From United States of America, joined Jul 2003, 8200 posts, RR: 28 Reply 1, posted (4 years 1 month 3 weeks 4 days 13 hours ago) and read 2175 times:
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Quoting Propilot83 (Thread starter): I had a question for anyone who is a commercial airline pilot. My question is "do the engine blades inside of the engines turn counter clockwise during reverse thrust at touchdown? and "during thrust reversal, where does the air intake flow through the engine or does air flow into the engine during thrust reversal? I understand that the engine exhausts are directed to blow forward instead of aft during thrust reversal, however during thrust reversal does the engine suck in any air or not? Thanks!
The engine continues rotating the same direction. Instead of the engine actually reversing direction, the airflow is ducted around and expelled forward.
So basically, air is still going into the engine inlet, and instead of all of it blowing out the back of the engine, some (or all, depending on the engine) of it is ducted to point forwards (usually at an angle - generally not directly forwards).
Here's an example in which all of the engine exhaust air is redirected (737-200):
And here's an example (much more common these days) in which only the bypass air is redirected (A340-300 - the core flow still exhausts out the back of the engine):
Rwessel From United States of America, joined Jan 2007, 1989 posts, RR: 2 Reply 2, posted (4 years 1 month 3 weeks 4 days 13 hours ago) and read 2175 times:
The engine itself does not reverse direction because you've engaged reverse thrust. Whether it's rotating clockwise or counterclockwise is up to the engine manufacturer, but it goes the same way all the time (at least when running - on a windy day the fan of a stopped engine is often spun gently in the wrong direction if the wind is from the back of the aircraft).
The reversers work by "bending" the stream of air coming out of the back of the engine to point forward. This can apply to the whole stream, or just the fan section, depending on the design, but the net effect is to get more thrust going forwards than backwards. Usually there's some sort of scoop or clamshell that sticks into the exhaust stream. Several decent pictures at:
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