The fastest you've ever been in a car?

[Larry N.]

There's no way that plane could take off. The conveyor belt keeps pace with the speed of the plane, which means the plane remains stationary from the POV of an observer on the ground, and therefore cannot lift off.

The conveyor belt keeps the plane stationary so there is no lift for the plane to take off.

Check out the Mythbusters video. The comments section is having a raging debate:

I love thread drift. If the mods hate it then they can simply split it off.

Tom, explain to me how the conveyor keeps the jet engines from providing thrust to actually move the airplane? Granted that it's possible that the wheels moving at 300 mph instead of 150 mph (or whatever figures) might incur some damage, but that doesn't stop the aircraft from moving, since the wheels just freewheel and have no effect on thrust (other than maybe some extra drag). What partially nullifies the thrust to just enough to keep the aircraft in place, thus not allowing the conveyor to move either, since the aircraft has zero speed if it stays motionless?

 

[SeilerBird]

Actually I don't care what the correct answer is. It is just a fun game for me.

It is a theoretical question so all the answers are theoretical therefore no one can be right or wrong.

The Mythbusters stunt proved nothing. They didn't use a 747.

 

[LarsMac]

Here is a question for you:

A 747 is on a conveyor belt on a runway. But the conveyor belt matches the speed in the opposite direction.

IOW, as the plane hits 100 mph forward, the belt matches the speed as 100 MPH in reverse. A reverse match at all speeds as the 747 tries to take off.

The question is:

Can the 747 take off normally?

-Don- Auburn, CA

That is actually a fairly absurd question. It is amazing how much energy has been expended on the concept.
This reminds me of a time many years back, when the conversation was over whether a Whale could sink a Battleship.
I think that we were 18 or 19, and we were very stoned.

 

[Ernie n Tara]

Doesn't matter what the conveyer belt tries to do. The jet simply rolls the plane down the runway (off the conveyer) and takes off. Alternately the conveyer is equal or longer in length to the take off run . In that case the wheels turn twice as fast and the jet takes off normally.

Ernie (mensan)

 

[DonTom]

There's no way that plane could take off. The conveyor belt keeps pace with the speed of the plane, which means the plane remains stationary from the POV of an observer on the ground, and therefore cannot lift off.

No, the belt only keeps up with the speed the wheels. The wheels will spin at double the normal speed and has nothing to do with the speed of the plane, which is powered at the wings, not at the wheels. It's unlike a car being on the same belt. The belt can cancel the power at the wheels in a car or motorcycle, but not in a plane.

How can the belt cancel-out jet power that does even NOT even exist in the wheels? The wheels have no motor connected to them or anything in a jet. They just run free. It's the power at the wings that move the plane, not the wheels.

But the belt will make the wheels spin twice as fast as they normally would, in the correct and same direction, clockwise. the plane takes off normally.

FWIW, I couldn't understand the speech in your video. Try to find something better in writing and doesn't mention the incorrect question, such as canceling out wheel speed, which is meaningless to the speed of the plane.

-Don- Auburn, CA

 

[DonTom]

It is a theoretical question so all the answers are theoretical therefore no one can be right or wrong.

Not true, we are dealing with well proven facts such as NO power being applied to the wheels from any engine or motor. You cannot cancel-out power that does not exist. That is fact, not theory.

-Don- Auburn, CA

 

[SeilerBird]

So your telling me that a 747 could sit perfectly still on a runway and turn on her engines full blast and the 747 would take off? If that were true then why bother to taxi?

 

[DonTom]

So your telling me that a 747 could sit perfectly still

The 747 will move at its normal speed if on the reverse-belt or not, so your question makes no sense. Nothing is sitting still when the jet takes off normally. The only difference is wheel speed, it must double in the same CW direction.

-Don- Auburn, CA

 

[Oldgator73]

If I see the plane I am due to board sitting on a moving conveyor belt I am not boarding unless I get an upgrade to first class.

 

[Larry N.]

So your telling me that a 747 could sit perfectly still on a runway and turn on her engines full blast and the 747 would take off? If that were true then why bother to taxi?

I'm telling you that not only CAN it do that, but that is exactly the way they do it every time. The reason for taxiing is simply to get to and from the runway, but you know that Tom, so I'll quit letting you pull the chain...

 

[Larry N.]

If I see the plane I am due to board sitting on a moving conveyor belt I am not boarding unless I get an upgrade to first class.

But first class doesn't go there...

 

[Oldgator73]

But first class doesn't go there...

Then I ain’t boarding.

 

[jymbee]

oops.. wrong thread.

 

[LarsMac]

I'm telling you that not only CAN it do that, but that is exactly the way they do it every time. The reason for taxiing is simply to get to and from the runway, but you know that Tom, so I'll quit letting you pull the chain...

So your telling me that a 747 could sit perfectly still on a runway and turn on her engines full blast and the 747 would take off? If that were true then why bother to taxi?

A 747 goes from dead stop on the runway to in the air in about 26 seconds. And it would not care if it started on a conveyor Belt.

 

[SpencerPJ]

OMG, stop

 

[Rene T]

Q pop

OMG, stop

AGREE!!!!!

 

[xrated]

OMG, stop

LOL....make my post about my motorcycle adventures speed runs seem pretty tame and not so far off topic huh?

 

[edjunior]

So how's the weather there? 100°F here.


-Don- Auburn, CA

It's hot here also. Hottest July on record so far. At my house, it's been between 101 and 105 for the last two weeks. We got 1/4 inch of rain one of those days, but all that did was piss off the grass. Yeah...it's just plain hot.

 

[Joezeppy]

It's been perfect here in Central NY the last month or so - 80's during the day and 60's overnight! Great sleeping weather! Been hotter this week though...and I maxed out at about 70 MPH in the truck while on vacation.

 

[DonTom]

OMG, stop

You all should know by now that I only stop when I have everybody else all straightened out on everything .

-Don Auburn, CA