Angular Momentum In A Helicopter

In summary, the conversation discussed the physics behind stabilizing a helicopter by calculating the force needed from the tail rudder. The initial approach was using conservation of angular momentum, but it was later questioned and the concept of energy was considered. There was also a mention of using the equation F=I*alpha/R to calculate the force. The conversation also briefly touched on the differences between single rotor and dual rotor helicopters. Additional information and research sources were also mentioned.
  • #1
godtripp
54
0
So we have a helicopter with a blade that has the moment of inertia "I" that is "2R" long and is spinning at an angular velocity [tex]\omega[/tex].

To stabilize the aircraft, the tail ruder must exert an equal an opposite force.

Can someone point me in the direction of how to calculate the force needed?

I'm thinking conservation of angular momentum, so I want to say

F=I[tex]\omega[/tex].

But I don't believe that's correct.
So I started thinking energy.

F=1/2I[tex]\omega[/tex].^2

Which still seems funny.


It's a problem I invented to test my understanding and prepare for the final, so if I'm missing a variable that would make this calculation easier let me know.

Thank you!
 
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  • #2
Hi there,

I am not an expert, and never really gotten close to a chopper, but I thought that they had more than one blade (3 or 4), placed opposite from each other. If my thoughts are correct, then the momentum of each blade should counteract the others.

Cheers
 
  • #3
Those are dual rotor helicopters, which have several varieties of how they can be aligned. However single rotor helicopters traditionally use the description above.

I did a little bit of wiki-research before I considered the physics.
http://en.wikipedia.org/wiki/Helicopter_rotor
The descriptions are rather brief and informative if you're interested.
 
  • #4
Ok so here's my thought L(Helicopter)=I(rotor)*Omega(rotor)

taking the derivative with respect to time on each side I get Torque=I*alpha(rotor)

So F*R=I*alpha

So F=(I*alpha)/R

is that correct?
 

Related to Angular Momentum In A Helicopter

1. What is angular momentum in a helicopter?

Angular momentum in a helicopter refers to the rotation of the helicopter's rotor blades around its central axis. This rotation creates a force that allows the helicopter to lift off and move in different directions.

2. How is angular momentum maintained in a helicopter?

Angular momentum is maintained in a helicopter by constantly adjusting the rotor blades' pitch, or angle, as well as the speed of rotation. This allows for the helicopter to maintain balance and control its direction of movement.

3. What factors affect the angular momentum of a helicopter?

The angular momentum of a helicopter can be affected by several factors, including the weight and distribution of the helicopter, the air density, and the speed and direction of the wind. Additionally, changes in the pitch and speed of the rotor blades can also impact the angular momentum.

4. Can the angular momentum of a helicopter be changed?

Yes, the angular momentum of a helicopter can be changed by adjusting the pitch and speed of the rotor blades. Changes in the weight and distribution of the helicopter, as well as external factors such as wind, can also impact the angular momentum.

5. Why is angular momentum important in helicopter flight?

Angular momentum is important in helicopter flight because it allows the helicopter to lift off and control its direction of movement. It also helps to maintain balance and stability during flight, making it a crucial factor in the safe operation of a helicopter.

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