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vic asked in Cars & TransportationAircraft · 3 months ago

Do thrust reversers produce enough thrust to stop an airliner without using the brakes?

Update:

I was thinking give the thrust reversers max thrust and brakes won’t be needed

Update 2:

I mean there is tons of thrust out the back, why can’t the same amount come out the front?

12 Answers

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  • 2 months ago

    Yes, but the plane will not stop as fast.

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  • 2 months ago

    As aircraft have increased in gross weights with higher landing airspeeds, the problem of stopping an aircraft after landing has greatly increased. In many instances, the aircraft brakes can no longer be relied upon solely to slow the aircraft within a reasonable distance, immediately after touchdown. Most thrust reverser systems can be divided into two categories: mechanical-blockage and aerodynamic-blockage.

    If the thrust levers are at idle position and the aircraft has weight on the wheels, moving the thrust levers aft activates the translating cowl to open closing the blocker doors. This action stops the fan airflow from going aft and redirects it through the cascade vanes, which direct the airflow forward to slow the aircraft. Since the fan can produce approximately 80 percent of the engine’s thrust, the fan is the best source for reverse thrust. By returning the thrust levers (power levers) to the idle position, the blocker doors open and the translating cowl closes.

    The thrust reversers cannot redirect the exhaust air 180-derees forward and it blows on a much lesser angle. The thrust produced is way below the 80 percent by the turbine wheels to almost half or less depending on the type or reverser install and the rmp of fan.

    Only MD-80’s/DC-9’s could use thrust reverser to back straight up they use a different type engine and reverser to accomplish this. The pilots are specially trained for this as they can see behind them and ground crews are their eyes.

    A&P/IA, DME mechanic examiner for the FAA., retired FAA inspector.

    Source(s): Reference FAA Powerplant Handbook FAA-H-80830-32A Chapter 3.
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  • JetDoc
    Lv 7
    2 months ago

    NOT before the end of the runway.

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  • 3 months ago

    Some turbo props can also perform that task.

    • JetDoc
      Lv 7
      2 months agoReport

      Turbo prop engines have variable pitch props that can be adjusted to produce braking force.  This is not the same thing as reverse thrust from a jet engine. 

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  • 3 months ago

    They will eventually, depending on runway length available, and indeed will not only stop the aircraft but also reverse it. However, it is normal practice to use both reverse thrust and braking to haul the speed down and then cancel reverse thrust when the speed is low enough not to overstrain the brakes.  This reduces unnecessary noise, turbulence, jet blast and flying debris.  Then the aircraft can taxi gently in using steering and brakes.

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  • 3 months ago

    Consider this: thrust reversers will allow an airplane to move backward from standstill.

    Which means that you have a retardation power from landing speed to zero and also with negative speed.

    So yes, the laws of physics imply that a plane could be stopped using only thrust reversers.

    But they usually are not, because at low speed, they tend to blow debris that could be re-ingested, potentially damaging the engines.

    Normally, the reversers are throttled down when reaching 60 knots or so, and the remaining thrust is usually adequate to reduce the speed further to 40 knots. This leaves the plane at a speed where brakes are quite effective and that is conductive to taxi out of the runway.

    As for your second update, engines on thrust reversers will never give the same thrust as they can pushing forward. In the case of high bypass turbofan, normally only the by passed is reversed, the primary flow from the hot core is still pushing forward, which means that the engines fights a little with itself. Then, there is the fact that making an airflow go 180 degree is never fully efficient, so you do lose thrust. Additionally, the thrust cannot be exactly 180 degree, as the air is taken from the back of the engine and directed forward, but there is the front of the engine in the way, so it ends up being at an angle.

    Source(s): Aerospace engineer
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  • They WILL eventually but it's going to take some distance to do it.

    On some aircraft the thrust reversers can actually be utilized to back up the aircraft.

    Some turbo props can also perform that task.

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  • 3 months ago

    Yes,they will stop it, but they will not stop it fast enough for the plane to make a short trip to the terminal. So they usually use the brakes too so they don't overshoot the terminal driveway.

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  • Anonymous
    3 months ago

    With a long enough runway yes.

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  • Rick
    Lv 5
    3 months ago

    depends on how much runway you have to slow down ..................

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