31 Oct 07
Originally posted by ZeddicusIt is a problem of logic, actually. And you've failed.
Edit - apologies for ranting. I like this forum with logic/physics/geometry puzzles etc, and it just bugged me to be caught out by a trick wordplay question, which is essentially what this then is. Better trivial than wordplay for me. :-(
31 Oct 07
Originally posted by PalynkaLol. If you say so. Read through the several topics on the boards and you will see that almost every single person to have reached the wrong conclusion has done so simply because of the incorrect grammar in the question.
It is a problem of logic, actually. And you've failed.
Agree to disagree I guess 🙂
31 Oct 07
Originally posted by ZeddicusI was just being a little provocative. 🙂
Lol. If you say so. Read through the several topics on the boards and you will see that almost every single person to have reached the wrong conclusion has done so simply because of the incorrect grammar in the question.
Agree to disagree I guess 🙂
But I don't think it's a question of grammar, but simply a question of not thinking thoroughly how planes take off, before jumping the gun and answering.
01 Nov 07
1 edit
Originally posted by ZeddicusActually the question is not poorly written, Its just that everyone that got it wrong says "the question is poorly written"
Lol. If you say so. Read through the several topics on the boards and you will see that almost every single person to have reached the wrong conclusion has done so simply because of the incorrect grammar in the question.
Agree to disagree I guess 🙂
"A plane is on a runway that can move (some sort of treadmill). The plane moves in one direction, while the conveyor moves at the same speed but in the opposite direction. Can the plane take off?"
The key is "CAN the plane take off?" Answer: YES, of course it can no matter what the treadmill does
or "CAN the treadmill keep the plane from taking off?" NO, because the treadmill has NO affect on the plane from pulling itself into the air.
Its not a poorly worded question, Its you guys not thinking it through.
** coming from a commercial pilot btw who done thousands of takeoffs, if that means anything 😞 **
01 Nov 07
3 edits
Originally posted by TheMaster37If the consideration is to match the speed of the tires to the airspeed required to rotate and take off you are correct, Marsan is wrong. An aircraft on a treadmill would only be matching the roll of the tires (or tyres) to the speed of the treadmill. There would be no forward movement which is required to gain airflow over the wings. As the speed of the aircraft relative to the ground increases so does the speed of the air as it passes over the wings, thus increasing the lift of the wings. It has nothing to do with how fast the tires roll.
How on earth would it be able to take off?
There is no lift from the air around the plane since the air isn't moving with respect to the plane.
Here's another way to look at it, you are outside walking on a treadmill facing into the wind, matching your steps to the speed of the belt. No relative movement to the world around you. If the speed of the belt increased so that you had to run as fast as you could to match the belt speed, with no relative forward motion, would the wind feel as it were blowing harder on your skin?
Nope.
Flyunity's explanation seems a little off. I think he means if the aircraft can overcome the roll of the treadmill enough to gain the airspeed required then sure, it will take off as it is making forward progress and gaining airflow over the wings and other flight surfaces.
02 Nov 07
Originally posted by flyUnityOf course it's poorly written. It never definitively says "the plane moves forward relative to the ground" or "the plane is stationary relative to the ground while the wheels turn". When people argue about this question, it's always about whether or not the plane is moving forward and getting air to flow over the wings. They can't agree because the question is crap. Didn't you read the other 40 million posts on this?!? 😕
Actually the question is not poorly written, Its just that everyone that got it wrong says "the question is poorly written"
"A plane is on a runway that can move (some sort of treadmill). The plane moves in one direction, while the conveyor moves at the same speed but in the opposite direction. Can the plane take off?"
The key is "CAN the plane take ...[text shortened]... rom a commercial pilot btw who done thousands of takeoffs, if that means anything 😞 **
02 Nov 07
Originally posted by PBE6"It never definitively says "the plane moves forward relative to the ground"
Of course it's poorly written. It never definitively says "the plane moves forward relative to the ground" or "the plane is stationary relative to the ground while the wheels turn". When people argue about this question, it's always about whether or not the plane is moving forward and getting air to flow over the wings. They can't agree because the question is crap. Didn't you read the other 40 million posts on this?!? 😕
But the question does ask "Can the plane take off" Answer is definitively yes.
If I was the pilot of the plane, with the goal to take off, and the treadmill operator tried to prevent me to takeoff, who would win?
The operator would be powerless to stop me
02 Nov 07
Originally posted by flyUnityThe operator would be able to marginally increase the amount of thrust the engines would have to create in order to take off.
The operator would be powerless to stop me
Consider if the planes engines are off and you turn the conveyor belt on. The plane will move backwards. The plane will have to turn its engines on and create thrust in order to remain stationary due to frictional forces between the wheels and the conveyor belt.
Beyond that though, the conveyor belt operator can't stop the take off.
02 Nov 07
Originally posted by flyUnityI'm in aviation too and I just don't see it. I would however love to lend an open ear to your explanation. If you would please, PM me and the others can maintain the debate here.
"It never definitively says "the plane moves forward relative to the ground"
But the question does ask "Can the plane take off" Answer is definitively yes.
If I was the pilot of the plane, with the goal to take off, and the treadmill operator tried to prevent me to takeoff, who would win?
The operator would be powerless to stop me
Thanks in advance,
Frank
02 Nov 07
Originally posted by Frank BurnsOk, lets put a winch on the front of the plane that has a cable tied to something stationary like a tree thats on the far end of the runway, now if you would start the treadmill, the plane would go backwards, however hook the winch up to the tree, start winding it up, and the airplane WILL move forward regardless what the treadmill is doing, the treadmill can be going 10 times as fast as the plane, but the winch is still going to pull the plane forward.
I'm in aviation too and I just don't see it. I would however love to lend an open ear to your explanation. If you would please, PM me and the others can maintain the debate here.
Thanks in advance,
Frank
Now replace "winch" to "propeller", and replace "stationary tree" to "stationary air".