When airplanes are parked at an airport, they should be left tethered to the ground. This is crucial to prevent them from rolling around the ramp because a fast enough airflow can make them take off. Thus, a question that comes to mind is whether planes can take off on a treadmill.
Yes, airplanes can take off on a treadmill. Planes can take off from a runaway even when it is moving in the opposite direction. A plane’s wheels produce low friction between the aircraft and the ground. So, planes can take off on a treadmill very quickly, but their wheels will spin slower than compared to a runway.
Having established that airplanes can indeed take off on a treadmill, the article will now get into details of how a plane can do it. So, keep on reading!
How Can A Plane Take Off On A Treadmill?
It is a common misconception that people think planes cannot take off on a treadmill. This is because they believe planes work the same way as cars. Cars cannot run on a treadmill, so they assume that planes cannot take off from it either.
However, this is untrue. A car’s wheels provide it propulsion by forcing the road to push backward, making the vehicle move forward. However, this is not what a plane’s wheels do. Contrastingly, a plane’s wheels are not motorized. Their primary purpose is only to reduce the friction between the aircraft and the ground during take-off.
Thus, what actually makes a plane take off are its propellers or jet turbines. They work to pull the air in a backward direction while pushing the plane forward. Therefore, once the pilot starts the engines, the plane begins moving forward at the same speed relative to the ground below and the air around it. This is without any regard to the speed of the conveyer belt.
This movement produces a lift on the wings, making the plane take off. Thus, making the plane’s wheels spin quickly is the only purpose of the conveyer belt. Therefore, a plane can easily take off on a treadmill if it is sufficiently long. It does not matter what the treadmill belt does because a plane’s energy acts on the air instead of the belt.
The rocket example can also explain how planes can take off on a treadmill. Imagine a rocket with wheels sitting on a treadmill instead of a plane. When the rocket is fired, it will eventually find its way toward the end of the belt and rocket off, proving that it does not remain still on the ground. Similarly, if it had wings, it would fly off the belt too.
Take a look at this Adam Savage video:
Other Factors That Help a Plane Takeoff From a Treadmill
As we have explained how planes work drastically differently from cars and how this enables them to take off from a treadmill, we will further detail other factors that help planes do so.
The Bernoulli Effect
Another critical factor that enables planes to take off on a treadmill is the Bernoulli Effect. This is related to the wing shape and its relationship with the rapidly moving air past it. A lifting force gets generated when the air that flows over the top of the wings is faster than the air under them.
The faster air creates lower air pressure, while the slower air generates higher air pressure. As the plane’s wheels only serve to hold it up, they will readily start moving on a treadmill as well. The only primary difference would be that they turn twice as fast as the average speed.
Roller Skates Analogy
Another analogy that can help us understand how planes can take off on a treadmill is through the use of roller skates. When wearing roller skates, we pull ourselves forward by grabbing onto the handles. This means that the method that allows us to pull ourselves forward is not the movement of wheels but instead our arms pulling the handles.
Similarly, the treadmill could be switched off, be at walking speed, or running speed, but it would not change a thing. Again, moving the plane forward is not the wheels’ function but rather the propulsion in the aircraft, regardless of the treadmill speed.
Therefore, as a plane’s forward motion relies on pulling air, it can do so even if the treadmill’s speed varies. As it moves forward and gains enough air force, it will be able to take off from the treadmill.
Thrust Force
Another factor that enables airplanes to take off from a treadmill is the thrust force. This force is generated by a reaction of the accelerating mass of air. Planes receive this thrust by accelerating on a working fluid at very high speeds.
When this thrust pushes the engine and the plane forward, it is equal and opposite to the force that is associated with the accelerated fluid from the back of the engine.
Put simply, the thrust that moves the airplane forward is just the opposite of the rate of change of momentum of the gas that is generated from the back of a plane’s engines.
Jet Engines
An airplane’s jet engines act upon the air around it instead of pushing against the ground. Thus, the plane will move in relation to this ambient air and generate a lift. This happens regardless of the movement of the tires because they are simply freewheeling, without any role to play in helping the plane take off.
However, if the treadmill speed is adjusted so that the airplane is positioned stationary relative to the ground, the plane will not be able to take off. It happens because the ground and air speeds are both zero. No lift will be generated, and the aircraft cannot push itself up to fly.
Final Takeaway
In conclusion, we can see that planes can take off from a treadmill, similar to how they would take off from a runway. Several factors help the plane, including the Bernoulli Effect, thrust force, and propellers.
