I would have to agree with this answer, it couldn't be more succinct.
IMO the aircraft would have to move first to trigger the conveyor.
Aircraft and conveyor belt (again)
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I would have to agree with this answer, it couldn't be more succinct.
IMO the aircraft would have to move first to trigger the conveyor.
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said before
dicovery tele said concord rotated at 200mphor knots(i cant remember)
the prog said that normal jet tyres would break up at this speed.
....... please dont shoot the messenger
in my mind, the plane in question is a 737 or similar.
i understand that they rotate at about 130.
in frictionless theory the plane would take off
make this real and i think the tyres would break up..
dicovery tele said concord rotated at 200mphor knots(i cant remember)
the prog said that normal jet tyres would break up at this speed.
....... please dont shoot the messenger
in my mind, the plane in question is a 737 or similar.
i understand that they rotate at about 130.
in frictionless theory the plane would take off
make this real and i think the tyres would break up..
With no friction the wheels would accelerate to much higher speeds even quicker and there will be a speed where the tyres and even the wheels would be destroyed by the centrifugal forces generated.
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Regarding the question ...
Luke_vibrator_uk wrote:
Can we assume that English is not actually your first (or maybe even second) language? ... Most people are generally comfortable with yes and no though ... Strange
What did you expect, a chapter from Aeronautics weekly
MW
To which I answered ... Yes
Luke_vibrator_uk wrote:
Duh ...Yes, being the answer to the question I was asked
Can we assume that English is not actually your first (or maybe even second) language? ... Most people are generally comfortable with yes and no though ... Strange
What did you expect, a chapter from Aeronautics weekly
MW
Orville and Wilbur are spinning in their f*****g graves
I presume their is some friction involved here............
KevNurse Wrote: Quote:
I have one question to ask megawatt:
Regardless of wheel speed and conveyor belt speed (which we are told, are equal), does the aircraft move forward relative to the ground surrounding the belt (or the air, if you wish; I'm assuming no headwind component)? The answer to this question is the crux of the matter.
Yes
OK, so we are discussing how/why the wheels are able to move the aircraft forward along the belt.
Here's the question, again:
You boys can talk about control systems and wheel drag to your heart's content, but the fact of the matter is that the belt is "controlled" (by whatever means) to match the speed of the wheels "exactly". It doesn't matter how it does it, the question itself says its a given condition in the problem. Its instantaneous. Its magic.
Therefore, if the wheels are going forward at 2 knots, the belt will go backwards at the same speed. Result: no forward movement of the aircraft. The pilot applies power, so there is an acceleration of the wheels. Acceleration is defined as metres per second per second and whatever the exact speed of the wheels at any time the belt is doing the same, exactly,so they will accelerate at the same rate.
The aircraft will not move fowards. It will not take off. The wheels and the belt will increase speed until a thrust/drag equilibrium is reached, but the question doesn't ask about that.
But, if you make up theories about the wheels having to move first to generate the signal for the belt's control system, i.e some kind of pseudo-realism, I would say that you are giving an answer to a question of your own creation.
The original question is clearly a hypo, but if you consider only the given conditions, there can only be one answer.
I have one question to ask megawatt:
Regardless of wheel speed and conveyor belt speed (which we are told, are equal), does the aircraft move forward relative to the ground surrounding the belt (or the air, if you wish; I'm assuming no headwind component)? The answer to this question is the crux of the matter.
Yes
OK, so we are discussing how/why the wheels are able to move the aircraft forward along the belt.
Here's the question, again:
You boys can talk about control systems and wheel drag to your heart's content, but the fact of the matter is that the belt is "controlled" (by whatever means) to match the speed of the wheels "exactly". It doesn't matter how it does it, the question itself says its a given condition in the problem. Its instantaneous. Its magic.
Therefore, if the wheels are going forward at 2 knots, the belt will go backwards at the same speed. Result: no forward movement of the aircraft. The pilot applies power, so there is an acceleration of the wheels. Acceleration is defined as metres per second per second and whatever the exact speed of the wheels at any time the belt is doing the same, exactly,so they will accelerate at the same rate.
The aircraft will not move fowards. It will not take off. The wheels and the belt will increase speed until a thrust/drag equilibrium is reached, but the question doesn't ask about that.
But, if you make up theories about the wheels having to move first to generate the signal for the belt's control system, i.e some kind of pseudo-realism, I would say that you are giving an answer to a question of your own creation.
The original question is clearly a hypo, but if you consider only the given conditions, there can only be one answer.
I agree.kevnurse said:
I disagree. If you think that turning the wheels faster will stop the aircraft moving forwards, then surely you must think that the wheels are somehow the reason that the aircraft moves at all.
If you think this, then how do you think the aircraft accelerates when it's off the ground?
Agreed. But the aircraft's forward speed will not change - the wheels will just rotate faster.
I disagree. I think it will do both.
In which case can we ignore "thrust/drag equilibrium"?
And yet there are two answers.
No we are not, the wheels are freewheeling, its the thrust of the jets which move the aircraft ( Newtons 3rd law of motion )
No, the aircraft must be moving FORWARD at 2 knots for the wheels to be doing 2 knots, remember they are freewheeling.
If the aircraft is not moving the wheels are not moving.
Concorde's wing is very thin (to reduce aerodynamic drag, so it can fly very fast with minimum friction and drag). It has a delta shaped wing to generate the lift that a thicker wing, carrying the same fuselage, would provide. Delta wings are not very "lifty" at lower speeds, so they have to point up more to generate a higher "alpha" (angle of attack) at lower speeds (less than 300 kts). Concorde cannot accelerate along the runway with its nose up, therefore it has to run along the ground at much higher speeds than conventional jets before pointing skywards. Normal aircraft tyres are big and bulky and take up a lot of space in their wings and fuselage. Concorde, necessarily by design, does not have space available for the normal tyre size associated with its weight and footprint, so the tyres have to be smaller to fit into the thin wing. A smaller tyre for the same ground speed of 200 kts on the runway are available to the military fast jet market, but Concorde goes faster than them as well, so it needs small, hardy custom-made tyres.
I've come to the conclusion that the question is impossible to answer.
The engine thrust pushes the aircraft forwards and the wheels, being in contact with the belt, must rotate. With no other conditions, the aircraft will move along the belt and take off.
However, the belt moves in the opposite direction and is supposed to be at the same speed as the rotation of the wheels, so there cannot be any foward movement along the belt. But the aircraft requires forward movement to fly. Its an impossible scenario.
In concept, this is like the picture of the tower with the ever rising steps around the side. It looks feasible but there is a trick of the mind.
The engine thrust pushes the aircraft forwards and the wheels, being in contact with the belt, must rotate. With no other conditions, the aircraft will move along the belt and take off.
However, the belt moves in the opposite direction and is supposed to be at the same speed as the rotation of the wheels, so there cannot be any foward movement along the belt. But the aircraft requires forward movement to fly. Its an impossible scenario.
In concept, this is like the picture of the tower with the ever rising steps around the side. It looks feasible but there is a trick of the mind.
M.C Escher
It might be a trick of the mind, but isn't that true of every trick? Or are some things tricks of the foot, or nose, or underpants?kevnurse said:
M.C. Escher's drawings all took advantage of one thing, being the way that humans learn to interpret a 3D perspective from a 2D image. Having learned it, it's difficult to put that aside when confronted with an unreal image.
The plane conundrum is entirely different. It's a test of the ability to separate the important from the unimportant; to interpret the written word and visualise the concept; to apply to the concept a set of rules that have been learned and proven; to understand the physical constraints, and to hypothesise and test a theory.
The glaring flaw in the theory of those who believe the plane won't take off (ignoring the exploding wheels distraction which I believe wasn't intended by the OP), is that not one of the non-take-off-believers is able to explain why, if a plane is able to move through the air at 500mph, with its wheels off the ground, they think it can't move through the air at 100mph with its wheels on the ground.
Thrust.
I'll say it again: thrust.
THRUST.
FFS
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