Dear friends and followers today, we're going to be talking about what is reverse thrust and when do we use it.
Okay, I'm going to break it down into the absolute basics. Reverse thrust is used to slow down the aircraft on the runway
after touchdown. There are three main components which slow down the airplane on the runway.
Primary is braking with disk or carbon brakes; which are similar to your car.
Secondary is reverse thrust what we're going to talk about today. Third is with
aerodynamical braking, with the ground spoilers. So we have two words in reverse thrust
It's "reverse" because the turbines output is being guided into the reverse direction
and as you might not know we apply thrust in order to increase the braking action.
So let's look at this video to see what happens at touchdown
Here you can see engine number one of an Airbus A320
At touchdown, these flaps open up, so called reverser doors
they act as guiding veins in the midsection of the bypass channel of the turbine and force the
accelerated air of the fan in the opposite direction. Now, these reverser doors don't open
automatically at touchdown
No,
you're gonna have to lift up these little levers which
activate the hydraulic system to apply pressure to the actuator which then opens the reverser doors.
Keeping the levers in this position will only give you idle reverse,
but as soon as you move the first levers to the aft position, the engine will spool up creating more thrust,
increasing reverse output. The engines will increase thrust up to 70%
Which then resembles in full reverse thrust I know it sounds a bit odd that we actually apply thrust again,
just after touchdown, but you can definitely hear the difference between idle and full reverse thrust, trust me.
Using the reverser
significantly decreases the landing distance;
varying between aircraft weight and environmental factors. If you look at this great video here showing a Boeing 747
touching down and applying full reverse thrust, you can clearly see how the water on the runway actually gets blown
forwards; sort of to the aircraft.
I actually experienced that myself landing on a snow-covered runway.
We applied full reverse thrust and you can literally see the snow blowing in front of the aircraft.
So when do we use for reverse thrust?
Using idle reverse at touchdown is mandatory by many aircraft manufacturers and airlines.
First and foremost, it immediately decrease the aircraft's speed and
To stabilize the aircraft's rollout plus to reduce to brake usage.
Landing on the wet or snow contaminated runways, using reverse thrust is absolutely vital to decelerate the aircraft and
preventing it from skidding and keeping it in a straight line. Full reverse thrust is not permitted at some airports due to noise abatement
procedures, or at least are restricted in between hours from then to then.
Nevertheless, pilots can use full reverse thrust when deemed necessary, but might have to state that in their decision in a report.
Airplanes with wind mounted engines may only use full reverse thrust until slowing down to
specified speed, because using the reverses below that speed could blow up loose gravel on the
runway; which could get sucked into the engine and damage the turbine.
For example on an Airbus A320 you would have to reduce full reverse thrust to idle
reverse at 70 knots and retract the reverse at the speed below 40 knots.
There are many different reverser types out there,
but all work after the basic principle by forcing the air, or even actually exhaust into the opposite direction.
So I hope I've answered another aviation related question for you. If you have a question that's been on your mind
don't hesitate to write me, therefore subscribe [to] my channel, check out my website, and
spread the word!
Farewell
- Your Captain Joe ;D
♪
Fairly often you see executive jets using reverse thrust during
taxi to reduce brake usage whilst rolling down a sloping taxiway.
Because of their high mounted engines pilots don't need to worry about damaging the turbine due to the gravel on the asphalt and
the well-known
MD80 with her rear mounted engines used to have a power back procedure,
where they used reverse thrust to back out of the gate position. I'm not hundred percent sure that procedure is still out there,
maybe you know. To me, it looks really dangerous because you have no clue where you're actually rolling.
So... I'll be that
Pssss... Subscribe to Captain Joe, he is amazing! -Mr. Captions