Plane on a Conveyor Belt

[iacas]

A plane is standing on a runway that can move (some sort of conveyor belt). The plane moves in one direction, while the conveyor belt moves in the opposite direction. This conveyor has a control system that tracks the plane's ground speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction). Can the plane take off?

Do not scroll below here before answer. The poll results are anonymous, so vote what you think.

Don't scroll. C'mon, be honest. You're a golfer, after all. :)

If you can see this message and haven't voted yet, this is your last chance to be honorable. Go vote.

Shame on you if you haven't voted yet and you're still scrolling. :D

Edited October 16, 2015 by iacas

[iacas]

Four votes but no responses yet.

And yes , we had this thread before. By me. :) This one has a poll though! :)

[GregZ]

I voted No, but have no idea why.

[dak4n6]

No. It's air flow past the wings that provide lift. Ground speed is irrelevant.

[Golfingdad]

Definitely not. The only thing on the plane that would be moving and thus providing any force at all would be the wheels. There would be no air flowing past the wings ... Unless ... There was a strong enough wind also flowing the same direction as the runway, I guess that would do it.

[David in FL]

I'm a pilot, and the answer is yes. I'll hide my reasoning for those who would prefer to figure it out on their own. [SPOILER=Warning: Spoiler!]. Forward movement of an aircraft is caused by the thrust of its propeller or jet, not by it's wheels like that of a car. Therefore, the movement of the conveyor in no way affects the aircraft's ability to move forward relative to its position through the air which is what generates lift and allows for flight. [/SPOILER] Btw, my fat fingers on my iPad actually caused me to record my vote incorrectly as no.....

[jamo]

Yep, it takes off.

[Golfingdad]

I'm a pilot, and the answer is yes. I'll hide my reasoning for those who would prefer to figure it out on their own. [SPOILER=Warning: Spoiler!]. Forward movement of an aircraft is caused by the thrust of its propeller or jet, not by it's wheels like that of a car. Therefore, the movement of the conveyor in no way affects the aircraft's ability to move forward relative to its position through the air which is what generates lift and allows for flight. [/SPOILER] Btw, my fat fingers on my iPad actually caused me to record my vote incorrectly as no.....

Ok ... I get it. I'm picturing it "running in place" but in actuality it would still be moving the same speed regardless of whether or not the runway is moving since the thrust comes from the jets, is that it? (I still vote no ... The friction on the wheels caused by them moving too fast will cause them to burn up and the plane will have to abort its takeoff ;))

[dak4n6]

Oh duh. The wheels do not propel the plane as with an automobile. The engines push the plane forward regardless of what the wheels are doing, so I hang my head in shame (esp as I am a scientist) and retract my NO vote.

[Golfingdad]

Oh duh. The wheels do not propel the plane as with an automobile. The engines push the plane forward regardless of what the wheels are doing, so I hang my head in shame (esp as I am a scientist) and retract my NO vote.

And I'm an engineer who also voted no. Oops. (Glad to have company in the "box of shame")

[dak4n6]

And I was thinking 'how could anyone vote yes?'

Hey, is Erik just trying to point out how many numbskulls hang out on TST?

[mchepp]

Also an engineers, although in my defense I am electrical and not aeronautical. I learned this one the hard way, loss of a bet. We were sitting in an airport and got into this argument overhearing a couple talking about this. A colleague and I bet dinner, to solve it we asked the pilot of the flight we were on. Sadly, I had to buy dinner. Many of you learned for less than me.

[David in FL]

Originally Posted by Golfingdad

Ok ... I get it. I'm picturing it "running in place" but in actuality it would still be moving the same speed regardless of whether or not the runway is moving since the thrust comes from the jets, is that it?

Yup.  If the plane needs to reach 100mph in order to fly, the wheels relative to the conveyor will be moving at 200mph, but the plane itself will still accelerate to 100mph relative to the air mass and will take off.

Don't feel bad, a LOT of people get it wrong.....

[bradsul]

I think this is really a stealth poll to find out who watches Mythbusters.

[mvmac]

I was honest and voted yes Thanks D-Plane

[Beachcomber]

I voted no... I too thought you needed air moving across the wings to provide lift.

[jamo]

I voted no... I too thought you needed air moving across the wings to provide lift. :tumble:

You do, but that doesn't have much to do with how fast the wheels are going.

[Golfingdad]

I voted no... I too thought you needed air moving across the wings to provide lift. :tumble:

Pretty sure every one of us who voted no thought the same thing. We jumped to the conclusion that the conveyor belt caused the plane to not be moving forward. But once you realize that the thrust is provided by the jets, you realize that it doesn't make a hill of beans of difference how fast or slow the conveyor belt is moving ... That plane will be moving the same speed regardless.