Can this be answered???

[Nitetimes]

"Imagine a plane is sat on the beginning of a massive conveyor
belt/travelator type arrangement, as wide and as long as a runway,
and intends to take off. The conveyor belt is designed to exactly
match the speed of the wheels at any given time, moving in the
opposite direction of rotation.
There is no wind.
Can the plane take off?"


Well can it?

[Loader]

According to Mythbusters......

http://mythbustersresults.com/episode97

[Nitetimes]

I know about that one too. But apparently there are two different versions of this question and they make for conflicting answers. I'm still looking for the original questions. I'll put it here when i find it.

Here's the videos from that show.

Part 1 - http://www.youtube.com/watch?v=MuXK1nr9_jg&feature=user


Part 2 - http://www.youtube.com/watch?v=U9STo3fjfGg

[Nitetimes]

I believe this is the original question and the one that is apparently creating the most controversy.
Some how people want to believe the wheels are removed from the equation.

On a day with absolutely calm wind, a plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. The conveyor has a control system that tunes the speed of the conveyor to be exactly the same (but in the opposite direction) as the plane speed.

Can the airplane ever take off?

[Wimperdink]

the wheels will create a lil friction but yes the plane can take off... If the plane was counting on the wheels to get it up to speed it would be a diff story. I think mythbusters called it pretty definitively.

[jeep_bluetj]

The wheels ARE removed from the equation. An airplane takes off on airspeed alone, groundspeed has nothing to do with it. If the wind is blowing hard enough, some ultralights can take off going reverse groundspeed. (They can fly 'backwards' -- they're not, really, but from a ground observer's point of view they are)

Sure, there may be a bit extra drag due to the wheels actually turning twice as fast as they would on a 'normal' takeoff, but that's insignificant.

[asianflava]

Haven't watched the show in a while, looks like Jamie upgraded his truck. Nice truck! hehe

[Nitetimes]

The wheels ARE removed from the equation. An airplane takes off on airspeed alone, groundspeed has nothing to do with it. If the wind is blowing hard enough, some ultralights can take off going reverse groundspeed. (They can fly 'backwards' -- they're not, really, but from a ground observer's point of view they are)

Sure, there may be a bit extra drag due to the wheels actually turning twice as fast as they would on a 'normal' takeoff, but that's insignificant.

On a day with absolutely calm wind, a plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. The conveyor has a control system that tunes the speed of the conveyor to be exactly the same (but in the opposite direction) as the plane speed.

Can the airplane ever take off?

I just got done reading pages of arguments on this and it's something.
The assumption on this one seems to be that the entire runway is moving backwards under the plane at the same speed the plane is going forward so therefore there is no lift created for the plane to take off.
Tho I am not entirely sure how that could happen.
My argument then would have to be that the runway may be moving but it couldn't negate the fact that the earth is still spinning normally and doing what it always does.

[starleen2]

Ok , but to throw into the mix – isn’t that what is happening when the airplane is landing? Isn’t the runway passing under the aircraft in the opposite direction at exactly same speed of the airplane above it getting ready to land?

[Jiminsav]

nope..plane will sit there and not lift an inch..
if the runway were moving in the opposite direction of the plane, there is no forward movement of the plane through the air, thus, there is no lift generated by the wings, so nothing happens.
but, if you throw on the brakes on the convayer belt, that plane will take off like a shot down the runway and be airborne in a flash.

[robfisher]

In one word...AIRSPEED. Just as stated above. If you fly into a headwind strong enough you can look down on the ground and see you planes shadow moving backwards across the ground. Now could a plane moving backwards still be flying?

[Kevin A]

The plane will go airborne, it doesn't matter what the wheels are doing underneath the plane.
http://en.wikipedia.org/wiki/Harrier_Jump_Jet

[asianflava]

I'm not too shure that the Mythbusters experiment is accurate, the plane HAS forward speed when it takes off. Is that forward speed while it is still on the ground or is it already in the air?

What they need to do is to pull the tarp, faster than the airplanes rotation speed. Give it a little reverse direction and see if it can overcome it. They also need to put a camera on the wheels to see the point at which it actually becomes airborne.

Regardless of how it takes off, the wings need lift. Wether the prop gnenrates enough lift is another story.

[ARKPAT]

As long as their is enought air flow on the wings surfaces to present lift. YEP ! It is an Air - Craft Carier.



Pat

[Gage]

It's simple like Jim says. You have to have air flow over the wings to create lift. So when the runway stops, the motor takes over and causes the plan to move forward which in turn causes air to flow over the wings and wala, airplane lifts off ground.

Question: How big of an engine would you need and how fast does it have to turn for the propeller to create enough air flow over the wings to make it fly on it's own?