Plane

[Deleted member 36735]

Hang on , are you suggesting a plane landing at 180 mph on a runway travelling toward it at 180mph will suddenly stop

Let's try and use a realistic example. You know the travellators in big airports like Heathrow?

If you walked towards one in the wrong direction at 5mph and it was travelling at 5mph towards you, once you stepped onto it and kept walking at the same speed, what do you think your movement would be in relation to the fixed ground outwith the travellator?

 

[Voyager EMH]

Wrong.
It's not a debate on ethics such as capital punishment where there can be equally valid opinions on both sides.
This is about very very simple facts, two different views are not necessarily equal and some of the stuff spouted has been absolutely staggering in it's stupidity.

Anyone could say the same whichever side of this debate they are on.
But trying to belittle someone for their view, "functioning human being", "spouting" is unnecessary.

I find your view that there are differing categories of debate, some factual and some opinion-only interesting.
Is there a god?

 

[Bunkermagnet]

Anyone could say the same whichever side of this debate they are on.
But trying to belittle someone for their view, "functioning human being", "spouting" is unnecessary.

I find your view that there are differing categories of debate, some factual and some opinion-only interesting.
Is there a god?

Yes, he played for Liverpool before they foolsihly sold him to Leeds.

 

[Arthur Wedge]

Shame it’s not a poll

 

[Deleted member 35927]

Let's try and use a realistic example. You know the travellators in big airports like Heathrow?

If you walked towards one in the wrong direction at 5mph and it was travelling at 5mph towards you, once you stepped onto it and kept walking at the same speed, what do you think your movement would be in relation to the fixed ground outwith the travellator?

You're clutching at straws here my friend, once again failing to understand the concept of propulsion. If I were walking then I'd become stationary if I were being dragged along by a jet plane at 5mph I'd continue to be dragged along 5mph, sure the travelator will slow me some I guess , but I won't reach a sudden equilibrium.

 

[Voyager EMH]

Let's try and use a realistic example. You know the travellators in big airports like Heathrow?

If you walked towards one in the wrong direction at 5mph and it was travelling at 5mph towards you, once you stepped onto it and kept walking at the same speed, what do you think your movement would be in relation to the fixed ground outwith the travellator?

If you moved towards the travellator on rollerskates (with very little drag) and your forward motion 5mph was due to a jet-pack strapped to you, what then?

 

[Deleted member 36735]

Anyone could say the same whichever side of this debate they are on.
But trying to belittle someone for their view, "functioning human being", "spouting" is unnecessary.

That's a viewpoint to which you are entitled, no problem,

I find your view that there are differing categories of debate, some factual and some opinion-only interesting.
Is there a god?

It's not that interesting though. If I say "maths is a really difficult subject", some people will have the opinion that it is and some will have the opinion that it isn't. Both opinions can be equally valid based on the level of difficulty relative to each person. If I say "2 plus 2 equals 5", that's not an opinion, it's an incorrect statement of a known maths equation that isn't open to opinion. My "opinion" on that would not hold any value as it is clearly factually incorrect.

Is there a god? The factual answer to that is that there are believed to be several thousand attributed to various worldwide beliefs.

 

[RichA]

The latter of those has not been suggested, only the first one.

I'm yet to see the explanation of how a multi hundred ton 747 goes instantaneously from zero airspeed to the minimum 180mph it requires to avoid falling out of the air.
And please don't bang on about the wheels again - they are irrelevant to the problem and everyone knows that.

 

[Deleted member 36735]

You're clutching at straws here my friend, once again failing to understand the concept of propulsion. If I were walking then I'd become stationary if I were being dragged along by a jet plane at 5mph I'd continue to be dragged along 5mph

No, if the jet plane was rolling along a runway at 5 mph but then hit a large travellator moving towards it at 5mph it would of course then become stationary in relation to the fixed ground, exactly the same as the pedestrian.
How on earth can you not see that?

 

[Swinglowandslow]

I get the impression that some are getting mixed up between thrust and lift.
A jet engine will thrust a vehicle on wheels at a speed in accordance with the amount of thrust.
In relation to its drag. If ,being a car, it will move forward on its wheels easier if it is a streamlined shape, I.e less drag. If it’s a bus it will need more thrust for the same speed.

However lift is required for take off. Lift is only generated when air is passing over an aerofoil in excess of a certain speed, depending on the thrust and drag of that unit, plane, bird , glider etc

 

[Deleted member 36735]

If you moved towards the travellator on rollerskates (with very little drag) and your forward motion 5mph was due to a jet-pack strapped to you, what then?

Obviously it would be the same.
You'd initially be travelling at 5mph but then the travellator moving in the opposite direction at 5mph would negate that.

 

[Deleted member 35927]

I get the impression that some are getting mixed up between thrust and lift.
A jet engine will thrust a vehicle on wheels at a speed in accordance with the amount of thrust.
In relation to its drag. If ,being a car, it will move forward on its wheels easier if it is a streamlined shape, I.e less drag. If it’s a bus it will need more thrust for the same speed.

However lift is required for take off. Lift is only generated when air is passing over an aerofoil in excess of a certain speed, depending on the thrust and drag of that unit, plane, bird , glider etc

I think some are getting cars and planes confused and the basic concept of how they are propelled and the differences therein.

 

[Swango1980]

No, if the jet plane was rolling along a runway at 5 mph but then hit a large travellator moving towards it at 5mph it would of course then become stationary in relation to the fixed ground, exactly the same as the pedestrian.
How on earth can you not see that?

We learnt it here first folks

If a plane was travelling at 180mph down a runway, then hit a giant treadmill travelling at 180mph in opposite direction, the people on board the plane would have a similar sensation of hitting a rock solid brick wall.

 

[RichA]

We learnt it here first folks

If a plane was travelling at 180mph down a runway, then hit a giant treadmill travelling at 180mph in opposite direction, the people on board the plane would have a similar sensation of hitting a rock solid brick wall.

Can you not see that you're suggesting that the 747 does the same impossible thing in reverse at takeoff?
How do you envisage the takeoff? Does it instantaneously achieve that 180mph to become and remain airborne or does it somehow manage to hover with minimal airspeed as it leaves the ground.

 

[Arthur Wedge]

From another site -



This question is at the best, ambiguous. There can be both yes and no answers based on what is being done with the aircraft and treadmill. The point is that for an airplane to lift off, there should be sufficient airspeed. If there is no wind, there airspeed is equal to the ground speed

Assuming that there is no wind (into or against the aircraft), there are two possible solutions.

• If the airplane is stationary relative to the ground, it won't take off (as wind speed is zero).
• If the airplane moves relative to the ground (with sufficient speed), it will take off.

Assume that we have a jet airplane (just for sake of argument) and some one pushes the throttle and it begins to move forward. Now, as the treadmill has an infinitely adjustable speed, we can have three conditions:

• If the treadmill speed is zero, the airplane will eventually generate sufficient lift and take off.
• If the treadmill speed is adjusted such that the airplane is kept stationary relative to the treadmill, the airplane will take off (as it is moving with respect to ground, and so has some airspeed).
• If the treadmill speed is adjusted so that the airplane is kept stationary relative to the ground, the airplane cannot takeoff, as the ground and air speeds are both zero. Note that in this case, the aircraft speed relative to the treadmill is twice that of the speed at which the treadmill is being operated.

If there is a wind, the required ground speed can be adjusted accordingly, but the principle remains the same. For example, if the wind speed is equal to the airspeed required for take off, the airplane will lift off even though it is stationary with respect to the ground.

Again, the important concept here is airspeed. It does not matter if the aircraft is on a treadmill, train track or runway.

 

[Deleted member 35927]

Can you not see that you're suggesting that the 747 does the same impossible thing in reverse at takeoff?
How do you envisage the takeoff? Does it instantaneously achieve that 180mph to become and remain airborne or does it somehow manage to hover with minimal airspeed as it leaves the ground.

No one has suggested that other than you. The plane will move forward along the conveyor and take off because it's engines are pushing it through the air, the conveyor is of no consequence, as long as the wheels are free to rotate the plane will be fine.

 

[Voyager EMH]

That's a viewpoint to which you are entitled, no problem,


It's not that interesting though. If I say "maths is a really difficult subject", some people will have the opinion that it is and some will have the opinion that it isn't. Both opinions can be equally valid based on the level of difficulty relative to each person. If I say "2 plus 2 equals 5", that's not an opinion, it's an incorrect statement of a known maths equation that isn't open to opinion. My "opinion" on that would not hold any value as it is clearly factually incorrect.

Is there a god? The factual answer to that is that there are believed to be several thousand attributed to various worldwide beliefs.

The "2+2 =" is a simple issue. The "plane on a conveyor belt" is more complex and needs to be broken down into parts, thought about and analysed.
Hence this thread has caught many people's interest.
I do not see it as simple facts, but as a concept to be thought about and discussed.
There have been posts representing two sides. Just about everyone's contribution makes sense to them. The sum of their thoughts so far, maybe.
I find it all interesting.

Some believe the plane will take off and some believe it will not. Debateable.
Some believe there is a god and some believe there is not. Debateable.

 

[Deleted member 35927]

From another site -



This question is at the best, ambiguous. There can be both yes and no answers based on what is being done with the aircraft and treadmill. The point is that for an airplane to lift off, there should be sufficient airspeed. If there is no wind, there airspeed is equal to the ground speed

Assuming that there is no wind (into or against the aircraft), there are two possible solutions.

• If the airplane is stationary relative to the ground, it won't take off (as wind speed is zero).
• If the airplane moves relative to the ground (with sufficient speed), it will take off.

Assume that we have a jet airplane (just for sake of argument) and some one pushes the throttle and it begins to move forward. Now, as the treadmill has an infinitely adjustable speed, we can have three conditions:

• If the treadmill speed is zero, the airplane will eventually generate sufficient lift and take off.
• If the treadmill speed is adjusted such that the airplane is kept stationary relative to the treadmill, the airplane will take off (as it is moving with respect to ground, and so has some airspeed).
• If the treadmill speed is adjusted so that the airplane is kept stationary relative to the ground, the airplane cannot takeoff, as the ground and air speeds are both zero. Note that in this case, the aircraft speed relative to the treadmill is twice that of the speed at which the treadmill is being operated.

If there is a wind, the required ground speed can be adjusted accordingly, but the principle remains the same. For example, if the wind speed is equal to the airspeed required for take off, the airplane will lift off even though it is stationary with respect to the ground.

Again, the important concept here is airspeed. It does not matter if the aircraft is on a treadmill, train track or runway.

Ok you've copied something from the internet. You'd need to supply source if you want it to be credible.

 

[Deleted member 36735]

We learnt it here first folks

If a plane was travelling at 180mph down a runway, then hit a giant treadmill travelling at 180mph in opposite direction, the people on board the plane would have a similar sensation of hitting a rock solid brick wall.

No they wouldn't.
They would still be moving "forward" at 180mph in relation to the treadmill but in relation to the ground they would not be moving.

 

[Arthur Wedge]

Ok you've copied something from the internet. You'd need to supply source if you want it to be credible.

Is the answer not credible then ?