Re: Imagine a plane is sitting on a treadmill...
 

I would say it has little to do with ground speed and everything to do with airspeed. Planes in the air have a "stall" speed, i.e. the minimum speed at which the aerofoil (wing) stops working and the aircraft becomes a stone.

If the treadmill is causing the plane to move backward but the air remains stationary, then the plane has a tail wind of 200mph, so by thrusting the engines to make it stationary it would cancel the tail wind and give 0mph.

It's a bit like travelling in the Jet stream. When you have a plane with 180mph tail wind, the plane actually does have to go faster to maintain airspeed. That's why a 6 hour flight sometimes takes only 5.

Re: Imagine a plane is sitting on a treadmill...
 

The question doesn't mention any wind.
Do we then presume the air around the stationary plane is static?
If so, ground speed will be very important as it is the only way you can present the airfoils to an airflow in order to create lift.

Re: Imagine a plane is sitting on a treadmill...
 

How would the treadmill make the air move backwards?

Its nothing like the jetstream...that a movement of the air, not a movement of the ground.

Re: Imagine a plane is sitting on a treadmill...
 

I think he's saying that, if the treadmill moved backwards (from the planes perspective) at 200mph, and the plane were to move backward with the treadmill, and there was no wind, the planes backward movement would create an air movement over the wings the same as a 200mph tail wind would with the plane stationary.
I think that's what he's saying but I've no idea what it has to do with the question.
Not criticising here, just not understanding your point Neill

Re: Imagine a plane is sitting on a treadmill...
 

Oh could be, although that makes the assumption that the treadmill going backwards will in fact make the plane go backwards if the engines are on at full thrust at the same time.

Re: Imagine a plane is sitting on a treadmill...
 

Check out this video for the maximum rejected take-off brake test for the Boeing 777.

All twelve wheels destroyed at a cost of $750,000. :eek::eek::eek:

http://www.youtube.com/watch?v=l5N2uBqJbVU

Re: Imagine a plane is sitting on a treadmill...
 

Never thought of it that way. I always considered the plane moving but one step back and it isn't so neither is the belt and if the belt isn't then the plane can go forward but if the plane goes forward then the belt will move and then .. babble babble blubber mutter scratch head stare blankly into space and ... oh stuff this I'm gettin out of here while I still have a bit of brain left to think with.

Re: Imagine a plane is sitting on a treadmill...
 

Wow, thanks for that...very cool!


$750,000 for 12 wheels! I wonder what snow tires would cost:D

Re: Imagine a plane is sitting on a treadmill...
 

But are they really necessary, loads of planes cope with all seasons :eek::rofl::p

Re: Imagine a plane is sitting on a treadmill...
 

But they get the runways cleared and swept for them when it snows.;)

We should be so lucky. :):)

Re: Imagine a plane is sitting on a treadmill...
 

I can't believe that this has gone on for so long.

The treadmill matches the speed of the plane, so the plane is moving forward......hear that.........moving forward.
Just because the treadmill is moving in the oppposite direction does not change the fact that the plane is moving forward.

You will get wing lift as the plane moves forward.....just the wheels will spin really fast as the treadmill moves backwards whilst the plane moves forward.

If the plane wasn't moving forward, there would be no speed and the question clearly states that the treadmill goes at the same speed as the plane.

Re: Imagine a plane is sitting on a treadmill...
 

If the treadmill is at zero and the plane is at zero then their speed is matched .... no no forget I said that I'm not here I'm going going gone.......

Re: Imagine a plane is sitting on a treadmill...
 

No...No....No..... the engines are going at take off thrust and it has been said that the brakes are off. The speed cannot be zero.

Re: Imagine a plane is sitting on a treadmill...
 

Fairies can fly, so why o why cant I - to Canada that is ...... :cry_smile:
Ooops sorry this is a an almost serious thread - too much vodka. :beer:

Re: Imagine a plane is sitting on a treadmill...
 

Now thats more like it. I can relate to this conversation:thumbsup: