Airplane and Conveyor Belt Debate

AI Thread Summary
In the discussion, participants debate the scenario of a 747 landing on a treadmill moving in the opposite direction at the same speed. The consensus is that the plane would roll off the treadmill without stopping, as the wheels would spin faster due to the treadmill's motion. Concerns are raised about the potential overheating of the landing gear bearings, which are not designed for such high speeds. It is emphasized that the plane's speed relative to the ground does not affect its airspeed, which is crucial for lift. Overall, the argument concludes that the treadmill does not provide any advantage in stopping the aircraft compared to a regular runway.
  • #151
There was some thread on this I saw a couple weeks back. Basically, it the wheels will turn however fast they want. As soon as the jets fire up the plane will move relative to the stationary ground. Any treadmill beneath it will just make the wheels spin faster. This would only be a problem if the wheels were motorized to make the plane move, but that's not the case.

On the other hand, If the treadmill was running at the same speed in the same direction as the jet as it fires up, the jet would take off with no movement of the wheels.

You don't need math or physics for this type of stuff, just think about it.
 
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  • #152
I seriously think that if this question shows up one more time, I'll scream.
 
  • #153
Well this is true and this is what I thought. But I thought that this was a good place to shoot it in the head for once and for all.

Everything I know of says that it's a stupid question and of course the aeroplane wouldn't take off - but when you have 50 different guys challenging your assumptions, you can begin to doubt yourself.

GJ
 
  • #154
Take a look at the other threads on the same subject, which mercifully have been locked. The plane will take off.
 
  • #155
oh yeah, i forgot about the fact that the wheels arent motorized, if the jets are what causing the movement the airplane would move... though i think that if the wheels spin too fast there would be lots of heat generation and the plane would move slower. (but if the wheels are ideal, it just means they would move twice as fast)
 
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  • #156
Point me to these other threads please?

GJ
 
  • #157
Look at 'Classical Physics' in the post entitled 'Airplane question: revisited'. There's a link in the OP to another.
 
  • #158
plane

hi
if you had a plane on a treadmill would it take off?
the treadmill is moving in the oppsite way of the plane at the same speed

thanks
 
  • #159
Welcome, deadmoon. Unfortunately, you introduced yourself with a question that has absolutely been done to death here. If you check back a few pages, you'll see a very thorough examination of the subject. Bottom line: yes.
 
  • #160
KILL IT! LOCK IT! QUICK! KILL IT! KILL IT TIL IT DIES FROM IT!

Argh!
 
  • #163
Plane on a moving runway

Hi all I've just signed up to the forum.
This question seems to have got over the net a bit so sorry if its a re-post

A plane is sat on a runway with some sort of conveyer belt, when the plane moves the conveyer moves in the opposite direction matching the planes speed exactly. Can the plane take off?
 
  • #164
Sorry, we've discussed this ad nauseum and won't go over it again. Do a search of the forum for the topic.

In short, though, the problem is so poorly worded as to not have a definite answer. Regardless, an airplane takes off when the airflow over the wings is fast enough to create enough lift to make the plane fly. That's it. It doesn't matter what the wheels are doing at the time (the plane can even be completely stationary if it has a strong enough headwind).
 
  • #165
Will the plane fly off ...?

If an airplane is placed on top of a conveyer belt which turns in the oposite direction of the plane with the exact speed as the plane, will it ever take off?
 
  • #166
This has been discussed over and over and over and over and over and over and the answer is basically yes with the qualification that the question is worded too poorly to be worth anything. Please search the general physics area.
 
  • #168
Conveyor and Plane

Sorry, this question is too fun too resist.

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

The question is:

Will the plane take off or not? Will it be able to run up and take off?

Well, to understand how the system works, let's change the settings first:

Instead going 100% of the speed in the opposite direction, have the conveyor belt go 700 knots in the opposite direction. The implications of this are obvious now since the air would be flowing backwards on the wings not forward, therefore the plane will be affected by this movement.

Another thought experiment. Put a Honda civic on a steel treadmill. If it has a spoiler, is the spoiler being used? It isn't. The only wind being generated is from the exhaust and the contact of the air with the moving surfaces of the vehichle and the steel treadmill. The body as a whole is not generating a lift or downforce as if it were traveling fast on the road.
 
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  • #170
...and will not be discussed again.

The question isn't fun, it's dumb. The only reason there is any doubt as to the answer is because the question is poorly worded and unrealistic (how can the conveyor exert a force on the plane?).
 
  • #171
Throwing Myself At Your Scientific Mercy

I'll hope you'll all excuse the intrusion, but I've fled here from another forum in the hope that you will be able to settle a debate that has been raging for far too long. The original question that has causes such furore is this:

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

The question is:

Will the plane take off or not?

I did try searching your forums, and saw a similar question with a car, but not a plane. I'm sat in the "no" branch, because I believe that there are no aerodynamic forces at work because essentially the airplane is stationary, and only the wheels are in motion, so you wouldn't get lift. However, the oppposing argument seems to be that the force from the jet engines would cause lift off regardless. I don't think any of us have a good enough grasp of physics to ever formally end this debate. Our formally peaceful forum has turned into something out of Gullivers travels, but instead of everyone divided on which way to eat a boiled egg we're going crazy over a hypothetical plane.

Twenty two pages later and the argument is still going.

So can someone kill this question dead for me?
 
  • #172
What forum is this?! We've received this question like 20 times!
 
  • #173
Yeah. What Forum Is It! Do We Have To Wipe Their A** For Them?? I think we need to do a DNS attack on them. And SPAM, yes Spam... :devil: :devil:
 
  • #174
Sorry, as I said, I did do a search and couldn't see it. The question I found was about cars. And as far as I know, I think it's quite viral, and been spread from place to place. Sorry for wasting your time.
 
  • #175
the plane isn't actually moving wrt anything other than the belt so there's no lift from air? surely.. hmm..
 
  • #176
Board searches are pretty fickle. If you do a search on "conveyor" you will get this thread (which links back to some of the original threads)

https://www.physicsforums.com/showthread.php?t=112124&highlight=conveyor

Please, someone go out into the ether and beg that this topic die a horrible death that it so rightly deserves and smote the boards that started it...amen.

BTW...what board is it that has had this raging debate going on for so long?
 
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  • #177
This question is fast becoming the Most Annoying Question (MAQ).

Zz.
 
  • #178
Debate

Hey people. I have a problem that I don't know the answer to, but you guys could probably help. Its quite a hot topic on other forums. Anyways, here it is.

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

Can the plane take off?

I say no personally but I've been told it can :rolleyes: help!
 
  • #179
This same question has been answered many, many times already, largely by people like you, P.G, who have come here from another forum. This question is no longer welcome here. Use the search function to find previous discussion on it.

- Warren
 
  • #180
plane landing on giant conveyor belt

What would happen if a plane was approaching a runway at 200 mph and the runway (conveyor belt) was moving at 200 mph in the opposite direction. I think if your wheels could take the sudden jolt, they would start turning at 400 mph. Since the plane is being thrusted buy a jet not attached to the wheels, it would continue to go its original 200 mph until the jet was shut off. Once that happens, at what rate do you slow the conveyor belt down so the that the plane is not forced of the back end of the belt. I can't get my mind around this one.. I heard a radio talk show host talking about this one day and was wondering if were possible.
 
  • #181
Please use the search function. Airplane or conveyer ought to get what you are looking for.
 
  • #182
Airplane. Fly up or not?

i have a some trouble in solution of this problem:
Airplane is standing on conveyer. Rate of movement of this conveyer automatically (without delay) concide with rate of movement wheels of undercarriage. Conveyer move to side reverse of course fly up airplane. This system is switch on. Question: airplane fly up or not?
 
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  • #183
Need more information. Each aircraft has a take-off speed based on the lift and weight of the aircraft.

Student is expected to show work (equations and computation) when asking for assistance.
 
  • #184
I think, what in order to this problem weight of this aircraft absolutely unimportant. This aircraft be able to fly up from usual landing strip. question:
can it fly up from conveyer?
 
  • #185
Read the guidelines.

We can not help you with schoolwork unless you show what effort you have made.
 
  • #186
This isn't homework. This is the airplane on a treadmill question that has been discussed ad nauseam.

Do a search for "treadmill" on the forums. You should find at least 10 other threads on this subject.

It looks like this is the longest thread on the subject: https://www.physicsforums.com/showthread.php?t=101259
 
  • #187
The very short answer:

An airplane's ability to take off has nothing to do with the movement of the ground under its wheels and everything to do with the movement of air over its wings.
 
  • #188
dav2008 said:
This isn't homework. This is the airplane on a treadmill question that has been discussed ad nauseam.

Do a search for "treadmill" on the forums. You should find at least 10 other threads on this subject.

It looks like this is the longest thread on the subject: https://www.physicsforums.com/showthread.php?t=101259
I wondered about that as soon as I saw "conveyor".

And as DaveC426913 has indicated, the solution has to do with the airspeed (airflow) over the wings. The air provides lift via the wings, which must be greater than the weight of the aircraft in order for the aircraft to 'takeoff'!

However, if the thrust of the engines are not increased to offset the force of the conveyor (once the aircraft lifs), then the aircraft will simply reduce speed due to drag and fall downward to the ground/conveyor. It's simple physics.

The question is ill posed and describes a physically unstable system.
 
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  • #189
dav2008 said:
This isn't homework. This is the airplane on a treadmill question that has been discussed ad nauseam.
I'm more than aware of the letter, but certainly not as sure as you about the former.

If some teacher decided to pose this question to a class (heaven forbid), then we're violating the Homework Help guidelines by responding to a query that includes no original work.

It's not our job to speculate about whether or not this is coursework. The location of this thread determines its fate. If the OP has posted in error, s/he can correct that with a PM to a mentor.
 
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  • #190
This questions are discussed on many many forums. On some of it this discussion last 3-4 years. Number of posts about this problem amount to 10 000. I simple want to know, what you think about it. Most of people incline to "The question is ill posed and describes a phyically unstable system."
 
  • #191
Kastey said:
This questions are discussed on many many forums. On some of it this discussion last 3-4 years. Number of posts about this problem amount to 10 000. I simple want to know, what you think about it. Most of people incline to "The question is ill posed and describes a phyically unstable system."
The problem as stated in the OP is ill-posed, i.e. it is too non-specific.

Replace conveyor or treadmill with catapult, and one has the situation on a naval aircraft carrier. Navies around the world have demonstrated that one can lauch an aircraft, but if the aircraft leaves the carrier deck without sufficient thrust, it crashes shortly after takeoff.

As soon the the force applied by the conveyor, treadmill or catapult is removed, the plane begins to decelerate because of drag and the lift (which is dependent on air speed over the wings) decreases as the forward velocity decreases and the plane descends.

This should not be hard to understand - and it certainly does not warrant 1000's of posts on countless websites. :rolleyes:
 
  • #192
Astronuc, I can't seem to understand what you are saying. Are you saying that yes it will fly because the thrust has nothing to do with the ground, or are you saying no for some weird reason?
 
  • #193
moose said:
Astronuc, I can't seem to understand what you are saying. Are you saying that yes it will fly because the thrust has nothing to do with the ground, or are you saying no for some weird reason?
Under certain conditions, that being forward thrust >= drag, and lift >= weight, the aircraft will takeoff.

However, as soon as the aircraft 'takes off', i.e. loses the force from the conveyor, treadmill, or catapult, unless thrust (force) is produced by the aircraft to match drag, drag will cause a rapid deceleration, and resulting lift will decrease, and plane will come back down.

When flying (cruising) in air, there is a force balance. Lift = weight, and drag = forward thrust. If one cuts off (stopped) the engines in flight, the plane would immediately decelerate (forward) and that would cause a rapid decrease in lift, which would cause the plane to plumment. That is not flying as much as it is falling!
 
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  • #194
Is there some sort of virus spreading around the internet that forces people to ask this same freaken question over and over and over? Does anyone know the source of this? Search the forum, it's been discussed beyond all reason.
 
  • #195
Lock the thread! Please!
 
  • #196
Please don't feed the trolls, Astronuc.

Kastey, this topic has indeed been discussed ad nauseum, mainly because people like you come here from other forums, don't bother to search, and post the same question again. It's not even an interesting physics problem -- the answer is definite and very clear, though the question is poorly worded.

Do not discuss this topic further here.

- Warren
 
  • #197
Question.

I wasn't really sure where this would go, and it seemed most sensable to place this question here since it wasn't a homework problem, just a random critical thinking problem. And with the anwser, could you also give a good explanation and proof.

A plane is sitting stationary on a runway. The runway is a giant conveyor belt that will instantly and inversely match the speed of the plane's wheels (wheels move at 10mph forward, runway moves 10mph in the opposite direction). As the plane accelerates the runway matches the planes speed.

Will the plane move? Will the plane take off?
 
  • #198
This has been posted before. The plane isn't wheel driven, it's air driven by the propeller (or jet). The wheels just spin faster, might slow the rate of acceleration a tad, but the plane would still take off (assuming the belt doesn't move so fast to cause the tires to explode from fast rotation). So if the plane takes off at 100mph, the tires just spin at 200mph, as long as they don't explode, there's no problem.
 
  • #199
Jeff Reid said:
This has been posted before. The plane isn't wheel driven, it's air driven by the propeller (or jet). The wheels just spin faster, might slow the rate of acceleration a tad, but the plane would still take off (assuming the belt doesn't move so fast to cause the tires to explode from fast rotation).

I can't see how the plane would infact take off. If there is no air flow over the wings (because the plane is stationary relative to the air) then the wings generate no lift. :confused:
 
  • #200
Jeff Reid said:
This has been posted before. The plane isn't wheel driven, it's air driven by the propeller (or jet). The wheels just spin faster, might slow the rate of acceleration a tad, but the plane would still take off (assuming the belt doesn't move so fast to cause the tires to explode from fast rotation). So if the plane takes off at 100mph, the tires just spin at 200mph, as long as they don't explode, there's no problem.

yeah I don't quite get what you mean. I sort of thought of it as like a man running on a treadmill, and assuming that the man runs at a constant rate of 8mph and the treadmill is at 8mph also, then the man will stay stationary. But since this is an airplane, and there's no foward momentum...then your saying the airplane would vertically lift up in the air?
 

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