think about this...

Blarg · #1 11-23-2005, 09:53 AM

If the plane is not moving, no air is being forced under its wings. If no air is being forced under its wings, there is no lift. So it stays grounded.

If a car were going 60 miles an hour and you stuck your head out the window, you'd feel a strong breeze in your face. Put the car on a treadmill that equalizes the speed, stick your head out the window, and you won't feel the wind rush through your hair.

Slow Play Ray · #2 11-23-2005, 10:00 AM

[ QUOTE ]
If the plane is not moving, no air is being forced under its wings. If no air is being forced under its wings, there is no lift. So it stays grounded.

[/ QUOTE ]

When did I say the plane wasn't moving?

Eurotrash · #3 11-23-2005, 10:03 AM

[ QUOTE ]
[ QUOTE ]
If the plane is not moving, no air is being forced under its wings. If no air is being forced under its wings, there is no lift. So it stays grounded.

[/ QUOTE ]

When did I say the plane wasn't moving?

[/ QUOTE ]

you essentially gave us two velocity vectors of equal magnitude that work in exactly opposite directions. the plane has zero velocity relative to somebody standing on the ground observing it. it is going nowhere.

i think.

Slow Play Ray · #4 11-23-2005, 10:05 AM

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
If the plane is not moving, no air is being forced under its wings. If no air is being forced under its wings, there is no lift. So it stays grounded.

[/ QUOTE ]

When did I say the plane wasn't moving?

[/ QUOTE ]

you essentially gave us two velocity vectors of equal magnitude that work in exactly opposite directions.

[/ QUOTE ]

All I really told you is that the conveyor belt velocity and the wheels' tangential velocity are equal, essentially. But does this address the plane's velocity?

Eurotrash · #5 11-23-2005, 10:09 AM

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
If the plane is not moving, no air is being forced under its wings. If no air is being forced under its wings, there is no lift. So it stays grounded.

[/ QUOTE ]

When did I say the plane wasn't moving?

[/ QUOTE ]

you essentially gave us two velocity vectors of equal magnitude that work in exactly opposite directions.

[/ QUOTE ]

All I really told you is that the conveyor belt velocity and the wheels' rotational velocity are equal, essentially. But does this address the plane's velocity?

[/ QUOTE ]

i'm misunderstanding the way you're phrasing this, I suppose. the comments I made above assumed that the forward velocity of the plane was exactly canceled by the reverse velocity of the conveyor.

I thought your original post was implying that with a setup like this one could get the plane to take off vertically like a harrier jet without the vertical engines

Slow Play Ray · #6 11-23-2005, 10:13 AM

so do you get it now?

FouTight · #7 11-23-2005, 10:07 AM

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
If the plane is not moving, no air is being forced under its wings. If no air is being forced under its wings, there is no lift. So it stays grounded.

[/ QUOTE ]

When did I say the plane wasn't moving?

[/ QUOTE ]

you essentially gave us two velocity vectors of equal magnitude that work in exactly opposite directions. the plane has zero velocity relative to somebody standing on the ground observing it. it is going nowhere.

i think.

[/ QUOTE ]

Everyone seems to be figuring this from the standpoint that the plane's wheels are where the thrust is comming from. The wheels do not push the plane forward, the props do.

#8 11-23-2005, 10:12 AM

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
If the plane is not moving, no air is being forced under its wings. If no air is being forced under its wings, there is no lift. So it stays grounded.

[/ QUOTE ]

When did I say the plane wasn't moving?

[/ QUOTE ]

you essentially gave us two velocity vectors of equal magnitude that work in exactly opposite directions. the plane has zero velocity relative to somebody standing on the ground observing it. it is going nowhere.

i think.

[/ QUOTE ]

Everyone seems to be figuring this from the standpoint that the plane's wheels are where the thrust is comming from. The wheels do not push the plane forward, the props do.

[/ QUOTE ]

Why is that relevant? The thrust from the props = X. The "thrust" from the moving conveyor-runway = -X. The aircraft is not moving relative to the air. Hence, no airspeed, so no lift.

Slow Play Ray · #9 11-23-2005, 10:13 AM

[ QUOTE ]
The thrust from the props = X. The "thrust" from the moving conveyor-runway = -X.

[/ QUOTE ]

this is wrong.

Running Bad · #10 11-23-2005, 10:18 AM

What everyone is missing is that the plane is attached to a hook on a launching arm, and the runway is oiled and there is a very low coefficient of friction. The wheels are just spinning wildly, it just happens to be the same speed as the conveyor belt. I hope this makes it easier to understand. [img]/images/graemlins/grin.gif[/img]

Cheers,
Rube Goldberg