Airplanes can be incredibly fast. Some military aircraft can even travel at supersonic speeds, like the infamous Lockheed SR-71 Blackbird, with its top speed of over 3500 km/h (2150 mph) — you are no doubt wondering whether aircraft have brakes and how they come to a standstill from these eyewatering speeds.
To slow down, airplanes use a variety of different methods, including hydraulic brakes, special control surfaces known as spoilers, and thrust reversers. In some cases, they will also be equipped with drag chutes which are primarily used for emergency purposes.
Below we will discuss some of the equipment and technology incorporated into common aircraft designs that enable them to stop. There would be a lot more crashes if aircraft were not designed with some or other means of slowing down.
Do Airplanes Have Brakes?
To generate enough lift to get off the ground, airplanes have to travel at high speeds down the runway. One thing you might start thinking about as you barrel down the runway is how on earth planes slow down from.
Airplanes typically have one or more braking systems that can be used on the ground and in the air. Wheel brakes are used on the ground, while special flight controls are used to slow the aircraft in the air and also on the ground.
Each aircraft design will use one or more methods to reduce its speed depending on the size and configuration.
Do Planes Have Brakes in Their Wheels?
When thinking about speed reduction, the disc and drum-style brakes found in cars and trucks will come to mind for most people. Most modern aircraft use a similar concept for ground braking purposes, with some of them having setups that are pretty similar to what you will find on land vehicles.
Aircraft do have brakes on their wheels that are used to control their speed and slow down while taxiing or after landing. These braking systems work on the same concept as a car’s brakes but will often have multiple rotors that operate slightly differently to common disc brakes.
Small airplanes like a Cessna 172 use single-disc brakes because they aren’t very heavy and are comparatively slow. On the other hand, large airliners will have much larger brake units with several discs actuated by hydraulic pistons to slow down.
Brakes are not only used for stopping the aircraft. Some airplanes do not have steering systems associated with their landing gear and instead will execute turns using a technique called differential braking — that is, holding the right wheel in place with the brake will cause the airplane to execute a right turn or vice versa for the left.
Does Airplane Have Brakes in Air?
Once airplanes are in the sky, the wheel brakes are not very helpful if and when they need to slow down. For example, when coming into land, they will have to reduce their speed somehow before touching down.
While in the air, aircraft use flight controls called flaps to slow down. These flight controls are located on the trailing edge of the wing and will move back and point down at an angle. This changes the shape of the airfoil to increase drag, slowing the airplane down.
Flaps are also used on takeoff — their primary purpose is to create more lift, enabling airplanes to get off the ground in a shorter time than they would otherwise. It might seem confusing that these surfaces also help the plane stop, but drag is a byproduct of lift — this is why airplanes need powerful engines in order to get (and stay) airborne.
Why Do Planes Slow Down Mid-Flight?
Anyone who has been on a 10-hour flight has no doubt wondered why the airplane slows to what seems like a crawl once they are up in the air. There are a few reasons for this.
The primary reason that airplanes slow down mid-flight is to conserve fuel. The aircraft uses a lot of fuel at the full power settings required to climb to flight altitude, and maintaining these high engine speeds would burn through the remaining fuel quickly.
You might love the roar of airplane engines, but the high speeds become inefficient at altitude — the faster the aircraft goes, the more drag it creates, which means diminishing returns not only in fuel efficiency but also in terms of engine cooling and longevity.
Airplane engines are not designed to run at full taps for extended periods and will begin overheating, increasing the risk of failure. Once up in the air, you don’t need as much thrust to stay there, so the engine speeds are reduced accordingly.
Check out this YouTube video for a further explanation of how airplanes brakes work.
How Do Planes Brake on Landing?
Landing is one of the scariest and most dangerous parts of any flight. Airplanes have to reduce their speeds quickly, which is a challenge considering how much weight they often carry.
Once on the ground, the airplane will use a combination of methods to brake. The wheel brakes will help reduce the rolling speed of the plane, and if equipped, ground spoilers and thrust reversers can also be used to bring the aircraft to a halt.
Ground spoilers (sometimes called air brakes) are located on top of the wings and will deploy upwards to “spoil” the airflow over the wing, thus increasing drag. They also increase the downward force and help the aircraft stay on the ground, making the wheel brakes more effective.
Thrust reversers do what they say on the tin — they are special mechanisms that divert the high-speed exhaust gases so that they travel outwards and forwards to slow the aircraft down.
In propeller aircraft, this can also be achieved by changing the propeller’s pitch to a negative pitch — this is known as the BETA (Beyond Efficient Thrust Angle) range.
Airplanes are generally designed with the principle of redundancy to pre-empt any mechanical failures. They will have 2–3 separate hydraulic systems capable of delivering pressure to the brakes in case one fails, isolating the faulty system.
Some aircraft are equipped with a parachute that deploys behind the aircraft to help it slow down in an emergency. This is called a drag chute. Typically, you will only find drag chutes on small private jets like a Cessna Citation or on some military aircraft.
Aircraft braking systems come in all different shapes and sizes, and most of the time, they will be purposely designed and built for a specific aircraft type.
For the most part, they are similar to those you will find on your car, but there are other complex components like thrust reversers and ground spoilers to help bring your flight to a safe standstill at the end.