how does aircraft brake to reduce speed when landed
In: Engineering
A combination of spoilers, engine reverse thrusters and brakes on the wheels.
The spoilers are upper surface flaps that deploy and disturb the airflow on the wing. They kill the lift on the wing to prevent the aircraft from getting enough lift to come up again, and create a lot of drag to help the plane slow down.
Engine reverse thrusters work exactly as the name implies. The jet plume from the engine is re-directed forwards, so the thrust acts backwards, thus slowing the plane down.
Wheel brakes work more or less the same as they do in a car.
The wheel brakes provide the majority of the deceleration, with the thrust reversers and spoilers assisting. We never rely on the reversers assistance, however. All landing calculations are achievable using just the wheel brakes.
Additionally to the above commenters. Aircraft that lands on aircraft carriers uses a system where ropes are used for additional braking.
Thanks everybody who contributed, sounds like many different systems exist and employed to brake the aircraft, it was not obvious when asking the question, so thanks so much
Everyone here is calling them spoilers. They’re literally just called speed brakes. Look at the [speed brakes](https://images.app.goo.gl/bB7wqePWGhPuNgmz7) on an A-10 Thunderbolt II for example. They pop open and literally create a shit ton of drag. Also people aren’t mentioning flaps. Flaps don’t actually slow the aircraft a whole lot, but they create a larger surface area on the wing surface to create more lift with slower speeds so the aircraft can slow down a very substantial amount before landing.
Some military jets deployed a parachute on landing. Called a brake chute. The brake chute is then jettisoned as the aircraft leaves the runway and some guys will drive over and collect it.
The brakes on aircraft are more heavy duty and substantial than cars. The aircraft wheel will have what’s called a brake pack, this is a sandwich made up of multiple brake discs and brake pads in layers (instead of one brake disc on a car) One layer will be stator the other rotor. The brakes get to hundreds of degrees C and some aircraft have cooling fans built into the wheels. It was common to have brake fires.
Some aircraft can move nozzles in their engines to deflect the exhaust in another direction towards the front of the aircraft. This is called reverse thrust.
I’d like to chime in with an additional “well actually”
The drag of the plane itself slows it down on landing as well. Particularly since landing typically occurs at engine flight idle throttle settings there so is minimal or no thrust to overcome that drag.
As previously mentioned in order to shorten the landing roll out phase aircraft employ many tricks such as thrust reversers, spoilers, air brakes, parachutes etc.
Flaps don’t specifically slow the aircraft down but they do allow it to go slower without stalling so you are able to land at a lower speed.
Latest Answers