So you have a plane and a conveyor belt....Does it take off?

[Prime]

Here's a better explanation and why the wiki article is in my mind, dodgy:

Imagine you have a ball on a piece of string and you spin it around. That ball is always trying to travel outwards along the path r or -r. This is centripetal force. This is what stops the ball from say, flying towards the centre.HMMM, that could be interesting

The only thing preventing your ball from flying of in the r or -r direction is the tension in the string.

Forcecentripetal - T = 0.

[doo_much]

There is no such thing as centrifugal force. Its centripetal acceleration.

kthxbaai.

Here's a better explanation and why the wiki article is in my mind, dodgy:

Imagine you have a ball on a piece of string and you spin it around. That ball is always trying to travel outwards along the path r or -r. This is centripetal force. This is what stops the ball from say, flying towards the centre.HMMM, that could be interesting

The only thing preventing your ball from flying of in the r or -r direction is the tension in the string.

Forcecentripetal - T = 0.

So.
What you're syaing is that, that which we call centrifugal force is actually centripetal acceleration?

[Prime]

There is no such thing as centrifugal force. Its centripetal acceleration.

kthxbaai.

Here's a better explanation and why the wiki article is in my mind, dodgy:

Imagine you have a ball on a piece of string and you spin it around. That ball is always trying to travel outwards along the path r or -r. This is centripetal force. This is what stops the ball from say, flying towards the centre.HMMM, that could be interesting

The only thing preventing your ball from flying of in the r or -r direction is the tension in the string.

Forcecentripetal - T = 0.

So.
What you're syaing is that, that which we call centrifugal force is actually centripetal acceleration?

in effect yes.

[doo_much]

So.
What you're syaing is that, that which we call centrifugal force is actually centripetal acceleration?

in effect yes.

So all that baloney and cr*p (sorry - math) wasn't really neccessary?



Go figure.


Soooo - Does the chopper take off?

Yes or No are acceptable answers.

[Sojourn]

helicopter on turntable or:
relevant neo-nazi image here

Luv turning your propeller the wrong way.. hehehe

[STIR]

Centrifugal force can be quite tricky (I know quite a few good engineers that still dont grasp it fully).....its not a real force, although it acts like one and can be used as one in calculations.

If you swing a stone on the end of a rope the real force is not what its trying to pull the rope out of your hand, but rather what is constantly changing the direction of the stone to force it in a circular pattern. This is called centripetal force which can be thought of as a 'pushing' force on the stone (although it is actually a pulling force in the rope) that constantly nudges the stone towards your hand so that it follows a circular path – (for most calculation purposes they are the same thing).

But anyway, to answer the helicopter on a turntable question:

If the helicopter has a perfect pilot that will be able to counter all centrifugal/centripetal forces and keep the helicopter on the turntable until take off then the model can be simplified to a ball sitting on a turntable with a rotor attached to it:

The ball could rotate at the same speed as the turntable or faster or slower, or it could even stand still, it doesn't matter, as soon as the rotors reach enough speed to supply sufficient uplift to overcome the weight of the ball/helicopter it will lift off.

[Monty]

What if the turn table is turning the other direction at the the same RPM of the helo's rotors? The rotors would be seen as standing still, so no air would be flowing over them. i think my reasoning is correct

[STIR]

What if the turn table is turning the other direction at the the same RPM of the helo's rotors? The rotors would be seen as standing still, so no air would be flowing over them. i think my reasoning is correct

I like your thinking but the rotors will only appear stationary if you viewed them while standing on the turn table. Relative to the air around the rotors, they will still be doing the required rpm for lift off.

[DarkStar]

Helicopter on a turn-table is an interesting one...

If the table turns the copter's body then no, it won't take off.
However, if there is a similar situation like the aeroplane (with the wheels spinning etc.), then logic tells me that yes it will take off.

[Sojourn]

Helicopter on a turn-table is an interesting one...

If the table turns the copter's body then no, it won't take off.
However, if there is a similar situation like the aeroplane (with the wheels spinning etc.), then logic tells me that yes it will take off.

Don't agree. The blades will have their interaction with the air around, thus creating lift, no matter what the body does.

[DarkStar]

I should have added that the turn-table will turn the body in the opposite direction, and at the same speed as the blades are spinning.

It would effectively be like holding the blades and letting the body spin freely.