# Centripetal Forces And Helicopters

• LuGoBi
In summary, the conversation discusses the reasoning behind a helicopter's movement when at rest in relation to the Earth. While the aerodynamic force and weight cancel out to keep the helicopter from falling, there is still a radial force between the Earth and the helicopter. This can be seen when considering the effects of other celestial bodies and how they may affect the helicopter's path. Ultimately, the nature of the forces at play plays a significant role in determining the helicopter's movement.
LuGoBi
I have a helicopter flying, but it is at rest in relation to the Earth, i.e., it's just hovering. That means the aerodynamical force equals minus the weight, so the forces cancel out, and the helicopter doesn't fall. But now, since the weight was cancelled, I can't say there's a centripetal force acting on the chopper and instead of rotating with the Earth, it should go off on a tangent. But that doesn't happen in reality. I wonder what's wrong with the reasoning.

Just because the forces add up to be zero doesn't mean that gravity doesn't pull on the helicopter. There is always a radial force between the Earth and the helicopter.

If there was no gravity the helicopter would just continue it's ascent radially outward of the Earth. Meanwhile the Earth would be spinning below the helicopter. Which simply isn't the case.

If we go to some point in space and observed the helicopter, it would be moving in a circle at a decently fast speed, in according to the Earth's spin.

Feldoh said:
Just because the forces add up to be zero doesn't mean that gravity doesn't pull on the helicopter. There is always a radial force between the Earth and the helicopter.

Yes, but the net force is zero, right? So how come it accelerates centripetally?

Imagine I have this helicopter over the Earth, and then I bring in another Earth, which is rotating in the opposite direction and put it in a way so the helicopter is equidistant to both "Earths". Then both planets would pull on the helicopter, the net force would be zero again, and what would happen? Would it rotate with one of the Earths or would it stand still? There's no reason why it would go along with one Earth and not the other, so it would probably stand still. And what's the difference between this case and the other one? The nature of the force, which in one case is an aerodynamical force and in the other is a gravitational force.

Sorry, what I just said is wrong. I didn't take into account the inital sideway velocity of the helicopter. But I still have doubts about this.

LuGoBi said:
I have a helicopter flying, but it is at rest in relation to the Earth, i.e., it's just hovering. That means the aerodynamical force equals minus the weight ...
Technically, (aerodynamic force + centripetal force) + gravitational force = 0. The helipcopter moves with the air, and assuming the air is still relative to the Earth's surface, then the helicopter moves in a very low circular path as the Earth and air rotate.

You could make things even more complicated by including effects from the moon, the Earth's orbit around the sun, the sun's orbit around the Milky Way galaxy, ...

## 1. What is centripetal force and how does it relate to helicopters?

Centripetal force is a force that acts on an object moving in a circular path, causing it to move towards the center of the circle. In the case of helicopters, the centripetal force is responsible for keeping the helicopter in a stable circular motion while it is flying.

## 2. How do helicopters use centripetal force to stay in the air?

Helicopters use their rotor blades to generate lift, which allows them to stay in the air. The rotor blades are designed in such a way that they create a circular motion, and the centripetal force generated by this motion keeps the helicopter in the air.

## 3. What factors affect the amount of centripetal force needed for a helicopter to fly?

The amount of centripetal force needed for a helicopter to fly depends on several factors, including the speed and altitude of the helicopter, the weight and size of the helicopter, and the air density and temperature. These factors can affect the lift and drag forces acting on the helicopter, which in turn affects the amount of centripetal force required for flight.

## 4. Can centripetal force affect the stability and control of a helicopter?

Yes, centripetal force plays a crucial role in the stability and control of a helicopter. It helps to keep the helicopter in a stable circular motion, and any changes in the amount of centripetal force can affect the helicopter's stability and control. Pilots must be aware of these forces and make adjustments to maintain a safe and stable flight.

## 5. How do helicopters use centripetal force to make turns?

When a helicopter wants to make a turn, the pilot will tilt the rotor blades in the direction of the turn. This change in the angle of the rotor blades creates an imbalance in lift forces, causing the helicopter to tilt in that direction. The centripetal force then acts to keep the helicopter in a circular path, allowing it to make the turn smoothly.

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