Many people assume that airplanes rely strictly on brakes to decelerate upon touching down on the runway. Most airplanes do, in fact, have hydraulic disc brakes. Located on the main landing gear wheels, they consist of heavy-duty carbon or metal discs and pads. When engaged, calipers will squeeze the discs and pads together, thereby creating friction against the wheel.
Airplanes, however, have other mechanisms to slow down. In addition to wheel brakes, many of them are equipped with nacelle thrust reverser cascades. Also known as cascade reversers, they are a type of internal thrust reversal system. Pilots typically deploy them when the wheels first hit the runway.
Overview of Nacelle Thrust Reverser Cascades
Nacelle thrust reverser cascades are fixed grooves or veins that redirect air to increase drag. They are typically integrated into the fan cowl where they sit flush against the nacelle. Because they produce drag, nacelle thrust reverser cascades can effectively reduce an airplane’s speed.
How Nacelle Thrust Reverser Cascades Work
They may sound complex, but nacelle thrust reverser cascades have a simple and straightforward method of operation. Pilots deploy them during landings to slow down. Upon touching down on the runway, pilots will pull the reverser levers. Actuators will then slide the nacelle sleeves backward.
With the nacelle sleeves open, doors known as “blocker doors” will redirect airflow. Rather than flowing straight out the back of the engine, air will move through the nacelle thrust reverse cascades. The cascades’ grooves or veins will essentially guide the air to increase drag and, thus, slow down the airplane.
Benefits of Nacelle Thrust Reverser Cascades
Nacelle thrust reverser cascades offer several benefits. For starters, they protect wheel brakes from premature wear and tear. Aircraft wheel brakes wear down just like automotive wheel brakes. They rely on friction that, over time, results in the gradual loss of disc and pad material.
Nacelle thrust reverser cascades don’t eliminate the need for traditional wheel brakes. Rather, they offer a supplemental method of slowing down so that the wheel brakes don’t do all the work. The end result is a longer operational life and less required maintenance for traditional wheel brakes.
Another benefit of nacelle thrust reverser cascades is a shorter landing distance. In dry conditions, they can reduce landing distances by up 30%. Nacelle thrust reverser cascades work in conjunction with wheel brakes so that airplanes can land on shorter runways.
