If you have ever played with a remote-controlled helicopter, you might have noticed that when you remove the tail rotor, the body of the helicopter starts to turn in the opposite direction of the rotor. This might seem like a violation of the conservation of angular momentum, but in reality, there is a simple explanation for it.
The Role of Angular Momentum
Angular momentum is a physical property of a rotating object, and it determines the amount of torque required to change the object’s rotational speed. In the case of a helicopter, the rotor blades transfer their angular momentum to the surrounding air, which allows the helicopter to stay airborne.
Here’s where things get interesting: to keep the rotor blades spinning at a constant velocity, the motor has to transfer angular momentum to the rotor. However, for every action, there is an equal and opposite reaction, according to Newton’s third law of motion. This means that an equal amount of angular momentum has to be transferred to the body of the helicopter, but in the opposite direction.
This results in the body of the helicopter starting to turn in the opposite direction of the rotor. However, the turning is not infinite because of friction with the ground. The angular momentum of the body of the helicopter is transferred to the ground, which ultimately slows down the spinning of the body.
The Role of Air Resistance
One might wonder what would happen if the experiment were to be conducted on a frictionless turntable. Here, the body of the helicopter would continue to increase its rotational velocity to an infinite extent. However, this is not likely to happen because of air resistance. As the helicopter gains rotational velocity, the air resistance to its motion increases, which creates a torque that opposes the helicopter’s motion. Eventually, the air resistance becomes so great that it matches the torque from the helicopter’s spinning body, and the rotation stops.
The Role of the Vacuum
In a vacuum, the body of the helicopter would not turn at all. However, this is a moot point because a helicopter cannot fly without air. The blades of the rotor create lift, which keeps the helicopter in the air, and without air, there would be no lift, and the helicopter would not be able to fly.
Conclusion
The conservation of angular momentum is a fundamental principle of physics, but to fully understand how it applies to helicopters, one must consider the principles of air resistance, lift, and friction. A helicopter’s rotor blades transfer angular momentum to the surrounding air, which allows the helicopter to stay airborne, but also creates an equal and opposite angular momentum transfer to the helicopter’s body. This movement is ultimately slowed by friction with the ground, air resistance, or both.
If you’re interested in learning more about the physics of helicopters, there are many resources available online and in print. Understanding the principles of lift, drag, and angular momentum is not only useful for those who fly helicopters but also for anyone interested in how the fundamental laws of physics apply to the world around us.
Angular Momentum = (Moment of Inertia) * (Angular Velocity)
This formula helps explain how a rotating object’s tendency to resist changes to its rotational speed is based on its moment of inertia and angular velocity. In the case of a helicopter, the rotor blades transfer their angular momentum to the surrounding air, which allows the helicopter to stay airborne while also creating an equal and opposite angular momentum transfer to the helicopter’s body.
Conservation of Angular Momentum In Helicopter
Conservation of Angular Momentum in Helicopters
If you have ever played with a remote-controlled helicopter, you might have noticed that when you remove the tail rotor, the body of the helicopter starts to turn in the opposite direction of the rotor. This might seem like a violation of the conservation of angular momentum, but in reality, there is a simple explanation for it.
The Role of Angular Momentum
Angular momentum is a physical property of a rotating object, and it determines the amount of torque required to change the object’s rotational speed. In the case of a helicopter, the rotor blades transfer their angular momentum to the surrounding air, which allows the helicopter to stay airborne.
Here’s where things get interesting: to keep the rotor blades spinning at a constant velocity, the motor has to transfer angular momentum to the rotor. However, for every action, there is an equal and opposite reaction, according to Newton’s third law of motion. This means that an equal amount of angular momentum has to be transferred to the body of the helicopter, but in the opposite direction.
This results in the body of the helicopter starting to turn in the opposite direction of the rotor. However, the turning is not infinite because of friction with the ground. The angular momentum of the body of the helicopter is transferred to the ground, which ultimately slows down the spinning of the body.
The Role of Air Resistance
One might wonder what would happen if the experiment were to be conducted on a frictionless turntable. Here, the body of the helicopter would continue to increase its rotational velocity to an infinite extent. However, this is not likely to happen because of air resistance. As the helicopter gains rotational velocity, the air resistance to its motion increases, which creates a torque that opposes the helicopter’s motion. Eventually, the air resistance becomes so great that it matches the torque from the helicopter’s spinning body, and the rotation stops.
The Role of the Vacuum
In a vacuum, the body of the helicopter would not turn at all. However, this is a moot point because a helicopter cannot fly without air. The blades of the rotor create lift, which keeps the helicopter in the air, and without air, there would be no lift, and the helicopter would not be able to fly.
Conclusion
The conservation of angular momentum is a fundamental principle of physics, but to fully understand how it applies to helicopters, one must consider the principles of air resistance, lift, and friction. A helicopter’s rotor blades transfer angular momentum to the surrounding air, which allows the helicopter to stay airborne, but also creates an equal and opposite angular momentum transfer to the helicopter’s body. This movement is ultimately slowed by friction with the ground, air resistance, or both.
If you’re interested in learning more about the physics of helicopters, there are many resources available online and in print. Understanding the principles of lift, drag, and angular momentum is not only useful for those who fly helicopters but also for anyone interested in how the fundamental laws of physics apply to the world around us.
This formula helps explain how a rotating object’s tendency to resist changes to its rotational speed is based on its moment of inertia and angular velocity. In the case of a helicopter, the rotor blades transfer their angular momentum to the surrounding air, which allows the helicopter to stay airborne while also creating an equal and opposite angular momentum transfer to the helicopter’s body.