Airplane on a Conveyor conundrum

[dieselboy]

So, if you overtake a cop car who is doing the speed limit, he'll not pull you over for speeding because the difference between you is less than the speed limit?

OK, I want you as my lawyer if I ever get pulling over.

LOL
if he was some sort of robot then no, he wouldnt pull me over as he would have no way of knowing that i was speeding.

our cars speed is measured relative to the ground, so by him moving, he cannot gauge my speed unless he knows his speed, and my speed away from him.

you can see how this would be almost impossible if we wasnt both travelling in exactly the same direction.

[dieselboy]

But the door isn't actively trying to match your speed, but in a different direction is it? It's just sitting still.
yep! correct, its sitting still relative to you, who is sitting in a chair watching me do funny walks away from a door


If the door was able to move, and had been told 'When he moves North at 10mph, you move South at 10mph' then when I start walking north, that door had damn well better start walking south.

BTW, this is nothing to do with the theory of relativity, that's more to do with the affect on time of speed.

[Slugsie]

well thats what you said!



ive done what you (the question) asked!

No it isn't, and no you haven't.

Look, I'm not going to bother arguing the point of how you measure the speed of the conveyor anymore. Why? Because it is in fact irrelevant. Which ever way you measure it (be it relative to the ground or to the aircraft) it will still have no appreciable effect on the ability of the aircraft to move forward through the air, generate lift, and fly.

[Slugsie]

LOL
if he was some sort of robot then no, he wouldnt pull me over as he would have no way of knowing that i was speeding.

our cars speed is measured relative to the ground, so by him moving, he cannot gauge my speed unless he knows his speed, and my speed away from him.

you can see how this would be almost impossible if we wasnt both travelling in exactly the same direction.

So, the system called Vascar that is fitted to the patrol cars and is able to tell the cops sitting in the car the speed of any car that passes (or they pass ) doesn't work huh?

*edit*
Sorry, it's not called Vascar, that is another speed measuring technology. The point is though that they do know how fast you are going when you whizz by them.

[dieselboy]

What about if we replace the airplanes wheels with castors (or some other wheel like mechanism that is free to rotate in any direction), and have a conveyor that is set to move at the same speed but at 90degrees to the aircraft? How does that work for you?

hell, put that plane on ice!
when the conveyor and the plane move, the conveyor will pull the plane over to one side.
the forward speed wont be effected, but it will be going 45 degrees to the direction of the opposite of the planes thrust. eg diagonal
:p

if you measured the conveyor speed from the ground, and it was made of ice,
and the thrust of the plane was only providing as much force as the drag produced by the conveyor then the plane would not take off

[dieselboy]

So, the system called Vascar that is fitted to the patrol cars and is able to tell the cops sitting in the car the speed of any car that passes (or they pass ) doesn't work huh?

dunno, how does it work?
ive never heard of it.
it must work by gauging the speed of that car by actively knowing the speed of the car its in. and adding the two together if the car in front is accellerating, and subtracting the two if the car in front is getting closer to it

[Slugsie]

dunno, how does it work?
ive never heard of it.
it must work by gauging the speed of that car by actively knowing the speed of the car its in. and adding the two together if the car in front is accellerating, and subtracting the two if the car in front is getting closer to it

Dunno exactly how it works, but I'm pretty sure it's along the lines you mention.

BTW, as per my edit, it's not called Vascar, that is a different system.

[Slugsie]

hell, put that plane on ice!
when the conveyor and the plane move, the conveyor will pull the plane over to one side.
the forward speed wont be effected, but it will be going 45 degrees to the direction of the opposite of the planes thrust. eg diagonal
:p

if you measured the conveyor speed from the ground, and it was made of ice,
and the thrust of the plane was only providing as much force as the drag produced by the conveyor then the plane would not take off

But why would the plane only provide as much force as the drag produced by the conveyor? Is there something about sitting on a conveyor that reduces the ability of an engine to work normally?

Remember, the plane is actively trying to take off, so the pilot will have the throttles set wide open.

[dieselboy]

No it isn't, and no you haven't.

Look, I'm not going to bother arguing the point of how you measure the speed of the conveyor anymore. Why? Because it is in fact irrelevant.
no it isnt, its the important factor here. why? because if the conveyor moves opposite speed relative to the plane, then the plane will take off. and if it moves opposite speed relative to the ground then it will not take off. Which ever way you measure it (be it relative to the ground or to the aircraft) it will still have no appreciable effect on the ability of the aircraft to move forward through the air, generate lift, and fly. yes it will!

:/

[dieselboy]

But why would the plane only provide as much force as the drag produced by the conveyor? Is there something about sitting on a conveyor that reduces the ability of an engine to work normally?

Remember, the plane is actively trying to take off, so the pilot will have the throttles set wide open.

ok, throttles wide open, and this means that in normal circumstances at this altitude, the plane can say reach 600mph only.
therefore the conveyor is going the opposite way at 600mph
in this case the plane will not take off.
the plane will be stationary relative to the ground.
this means, the plane will appear to be stationary.

[Slugsie]

:/

Explain how the speed of the conveyor *whatever it is* is able to act upon the aircraft? All the aircraft has to do is overcome the friction within the wheels. Seeing as it is able to do that in a normal takeoff, then it will have no problem doing it when sat on a conveyor that may *or may not* be changing the rotational speed of the wheels (and that is all that it can do).

[dieselboy]

Dunno exactly how it works, but I'm pretty sure it's along the lines you mention.

BTW, as per my edit, it's not called Vascar, that is a different system.

they probably gauge the speed of the police car by gps, but who knows lol

[Slugsie]

ok, throttles wide open, and this means that in normal circumstances at this altitude, the plane can say reach 600mph only.
therefore the conveyor is going the opposite way at 600mph
in this case the plane will not take off.
the plane will be stationary relative to the ground.
this means, the plane will appear to be stationary.

Err, so where exactly is all the thrust from the engines going? It's certainly not being directed into the conveyor, as that is not how an aircraft directs its thrust.

[Slugsie]

OK, look, go here:

http://www.youtube.com/results?searc...s&search_type=

Watch the top two videos.

IT ACTUALLY HAPPENED!

[Slugsie]

they probably gauge the speed of the police car by gps, but who knows lol

No, police patrol cars (note, not panda cars) have calibrated speedos, that's how they know their speed. The speedo has to be calibrated regularly, if it hasn't been done properly you can use that fact to fight a speeding ticket.