# Helicopter rotor acceleration

1. Dec 4, 2011

### max1546

How would you calculate the acceleration of the following two points?

http://img341.imageshack.us/img341/917/helicoptor.jpg [Broken]

The diameter of the hub = d
The length of the rotor = l
The flapping angle: theta = A sin(omega*t)
The rotation speed of the rotor system = Omega

2) A warm crawling from the tip to the hinge

The current position from the hinge = x
The speed along the blade = v (inward)

I'm trying to find the acceleration by the method of moving frame and it's getting tricky...

Last edited by a moderator: May 5, 2017
2. Dec 5, 2011

### 256bits

In the picture shouldn't that be d/2 rather than 2/d as the radius from the centre to the hub edge?
Out of curiosity, what is A?

Nonetheless, in what direction would the worm feel an acceleration?
If the worm has moved to another position closer to the hub, how has the acceleration that it feels changed?
I think if you set up your equations regarding centripetal acceleration you should be able to solve.

As the worm moves inwards, the radius is changing (as above) so the worm's tangential velocity is also changing. Thus there is also a tangential acceleration, which you can solve for.

You could try using polar coordinates.
here is a description from Wiki
http://en.wikipedia.org/wiki/Circular_motion

Last edited: Dec 5, 2011