Plane

[Swango1980]

Well, H is the one who gave us the image. Was he too lazy to describe it accurately in words.

And I still think that parameters like friction etc aren’t being taken into account.

But as Ken says, maybe it’s time for H to go out and try the real thing on the lake or river, and take some proper bait with him

There is a possibility the image was simply a schematic so the audience could immediately understand the concept? A runway sized treadmill might have just looked like a runway, not a treadmill. And as it is a meme, providing a detailed description, terms and conditions might have felt unnecessary.

It's up to the audience to interpret it. And the audience are welcome to layout what they've assumed in their response

Indeed, frictional effects are not being taken into account. But it's irrelevant, as frictional forces will have no impact on the plane taking off or not, which was in the question.

 

[Voyager EMH]

Lets say the conveyor or treadmill is running at 500mph.

For the plane to remain stationary, the pilot needs only a tiny amount of power from his engines. The same amount of power as when the conveyor was at 10mph.
The pilot and the engines can not make the wheels of the plane spin faster. The conveyor speed makes the wheels spin, to maintain stationary position.
All done with little power from the engines.

But here is the big step. The big change in perception for some.
An increase in power from the engines will cause the plane to move forwards against the conveyor.
Even though the conveyor is going at 500mph, the plane will take off as normal.
The conveyor does not make-it-harder for the plane to move forwards and take off.

But the OP said the conveyor will match the speed of the wheels? And keep increasing speed if necessary.
Yes.
The conveyor and the plane wheels will always have matched speeds. The conveyor spins the wheels, not the engines.

An increase in speed of the conveyor does not need more power from the engines for the plane to remain stationary.
An increase in speed of the conveyor merely spins the wheels of the plane faster while the plane is stationary.

The plane needs only a small amount of power to remain stationary.
Full power from the engines and the plane will move forwards and take off as normal.

Thread killer.

Great thread though. Very thought provoking.
Some excellent discussion and debate.
Thank you all for the entertainment. All views were interesting reading.

 

[Swango1980]

Lets say the conveyor or treadmill is running at 500mph.

For the plane to remain stationary, the pilot needs only a tiny amount of power from his engines. The same amount of power as when the conveyor was at 10mph.
The pilot and the engines can not make the wheels of the plane spin faster. The conveyor speed makes the wheels spin, to maintain stationary position.
All done with little power from the engines.

But here is the big step. The big change in perception for some.
An increase in power from the engines will cause the plane to move forwards against the conveyor.
Even though the conveyor is going at 500mph, the plane will take off as normal.
The conveyor does not make-it-harder for the plane to move forwards and take off.

But the OP said the conveyor will match the speed of the wheels? And keep increasing speed if necessary.
Yes.
The conveyor and the plane wheels will always have matched speeds. The conveyor spins the wheels, not the engines.

An increase in speed of the conveyor does not need more power from the engines for the plane to remain stationary.
An increase in speed of the conveyor merely spins the wheels of the plane faster while the plane is stationary.

The plane needs only a small amount of power to remain stationary.
Full power from the engines and the plane will move forwards and take off as normal.

Thread killer.

Just to point out, the speed of the wheels isn't just a function of the treadmill. (Otherwise on a normal runway they wouldn't move as a plane takes off). They are Velocity of Plane -Velocity of Ground. The ground Velocity obviously being a negative

Of course, people need to remember what starts the wheels on an airplane moving in the first place....the forward movement of the plane. So, if the plane remains still, the wheels will never turn and the treadmill will never move.

 

[backwoodsman]

As an aside (please, God, let it be an aside ...) if the conveyor is going at, say, Voyager's 500mph, then I suspect the wheels will spinning at 500mph + forward motion. IE, well beyond their design tolerances. Won't the tyres explode, plane blow up and launch itself skywards. So plane gets off the ground either way ... ?

Ps. For clarity - yes, I'm still happy to be in the 'takes off as normal' camp

 

[Deleted member 35927]

I have to say, @hambugerpete is a master fisherman.

I was interested to know what people thought. I really did think most would just say yes it obviously can take off and that be the end of it.
I'd happily see more threads like this and it even stayed well mannered for the most part !!

 

[Voyager EMH]

Just to point out, the speed of the wheels isn't just a function of the treadmill. (Otherwise on a normal runway they wouldn't move as a plane takes off). They are Velocity of Plane -Velocity of Ground. The ground Velocity obviously being a negative

Of course, people need to remember what starts the wheels on an airplane moving in the first place....the forward movement of the plane. So, if the plane remains still, the wheels will never turn and the treadmill will never move.

True.
The change in perception was my aim in that last post.
I tried with some analogies of an airport travellator.

If I could walk alongside a travellator with my trolley on the travellator which is running at 5mph against me, it is not harder for me to push that trolley along than if it were with me on the static corridor.
Provided my arms are long enough to reach over etc.
The travellator does not require more power to make the trolley move forwards. Same power on static ground - same power on a travellator - to move it forwards in the same way.
Same power as normal for a plane to take off on a conveyor.

 

[Swango1980]

A plane only leaves the ground when it gets 'lift off'. That only happens when the plane moves quickly relative to the air it is in.

Tents blow away (get lift off) when the wind is very strong.

True. I'm pretty sure 100% of people in here understand that. But thanks for the confirmation

 

[Deleted member 35927]

Well, H is the one who gave us the image. Was he too lazy to describe it accurately in words.

And I still think that parameters like friction etc aren’t being taken into account.

But as Ken says, maybe it’s time for H to go out and try the real thing on the lake or river, and take some proper bait with him

I didn't create the image or add the text. I guess that it assumes a degree of obviousness in that a jumbo requires a decent length of tarmac to take off, so defining accepted norms is pointless. When I read I assumed the conveyor is the length of the runway.

 

[sunshine]

True. I'm pretty sure 100% of people in here understand that. But thanks for the confirmation

No, only 98% understand it. 2% don’t: that’s you and hamburglar

 

[Crow]

It is not a treadmill.

If people looked back at the original post they'd see that it says conveyer belt.

And the conveyor belt counteracts the rotation of the wheels, which means that it must be travelling in the same direction and at the same speed as the plane so that the wheel does not turn.

(Conveyer belts can be miles long)

 

[Bunkermagnet]

Its an irrelevant question. Being a Boeing, it's bound to crash anyway.

 

[Voyager EMH]

It is not a treadmill.

If people looked back at the original post they'd see that it says conveyer belt.

And the conveyor belt counteracts the rotation of the wheels, which means that it must be travelling in the same direction and at the same speed as the plane so that the wheel does not turn.

(Conveyer belts can be miles long)

And with that interpretation of the wording the plane takes off as normal as well.

Unless I'm wrong.

 

[Crow]

And with that interpretation of the wording the plane takes off as normal as well.

Unless I'm wrong.

Of course.

 

[Deleted member 35927]

No, only 98% understand it. 2% don’t: that’s you and hamburglar

Don't understand what ? The plane conundrum,? plenty have the same correct answer as me. Lots of easy to follow explanations to read in here.

 

[Swango1980]

No, only 98% understand it. 2% don’t: that’s you and hamburglar

Of course, we've already clarified that the plane moves forwards. You either missed that, or conveniently ignoring to for motivations unknown to me?

 

[RichA]

Ffs. I'm still thinking about it.
Isn't there some kind of paradox?
If the rotation of the wheels and the speed of the conveyor belt are constantly perfectly matched then they could be considered being geared at a 1:1 ratio, as if cogged. Therefore the plane can only move forward on the belt if its wheels are going faster than the belt. Which breaks the rules set out in the puzzle.
Doesn't it?

 

[Deleted member 35927]

Ffs. I'm still thinking about it.
Isn't there some kind of paradox?
If the rotation of the wheels and the speed of the conveyor belt are constantly perfectly matched then they could be considered being geared at a 1:1 ratio, as if cogged. Therefore the plane can only move forward on the belt if its wheels are going faster than the belt. Which breaks the rules set out in the puzzle.
Doesn't it?

No it's all good, no paradox, you'll give yourself a headache

 

[RichA]

I think the natural result is that the thrust of the engines eventually topples the plane forwards.

 

[Deleted member 36735]

Of course, we've already clarified that the plane moves forwards. You either missed that, or conveniently ignoring to for motivations unknown to me?

You haven't actually "clarified" anything.
You and the guy that can't spell hamburger have put forward very vague descriptions without any scientific facts behind them that you claim to be proof. When you say people are "ignoring", they are actually just disagreeing with your hair-brained ideas. A modern day version of that is Trumpism at its finest.

The bottom line though, is that none of us can actually be correct.

A quick Google search shows that this conundrum has been around on the internet for nearly 2 decades, with thousands of arguments for and against the plane taking off very similar to those in this thread. The specific wording of the question makes it impossible to answer as it is vague and causes disagreement on what is actually happening, the fact that 400 posts in and people are disagreeing with the actual scenario rules is a good example of that.

From the wording of the question, nobody can categorically say that the plane will take off or that it cannot take off, and that's the whole point of the clever conundrum in the first place.

The only people who are wrong are those of us who believed one way or another, which is basically all of us

 

[Deleted member 35927]

You haven't actually "clarified" anything.
You and the guy that can't spell hamburger have put forward very vague descriptions without any scientific facts behind them that you claim to be proof. When you say people are "ignoring", they are actually just disagreeing with your hair-brained ideas. A modern day version of that is Trumpism at its finest.

The bottom line though, is that none of us can actually be correct.

A quick Google search shows that this conundrum has been around on the internet for nearly 2 decades, with thousands of arguments for and against the plane taking off very similar to those in this thread. The specific wording of the question makes it impossible to answer as it is vague and causes disagreement on what is actually happening, the fact that 400 posts in and people are disagreeing with the actual scenario rules is a good example of that.

From the wording of the question, nobody can categorically say that the plane will take off or that it cannot take off, and that's the whole point of the clever conundrum in the first place.

The only people who are wrong are those of us who believed one way or another, which is basically all of us

This is untrue , it can and has been explained many times. It's just basic science, one of us is using classic trumpism and it's not me.
If you feel you can override sir Isaac Newtons laws then please explain rather than just a long rant about how we are all wrong and you're not, but failing to back your claim with any substance other than a quick Google , only yesterday you suggested a plane will dead stop if landing on a conveyor belt moving opposite to it