Plane

[Deleted member 35927]

A 747 needs to be moving through the air at 180mph to maintain altitude (at sea level).
When it's on the conveyor belt its airspeed is zero, however much air is being sucked through the jet engines. It can't instantaneously accelerate to 180mph as it leaves the ground.

Why is it zero ? Makes no sense, you're being misled by a treadmill

 

[RichA]

Why is it zero ? Makes no sense, you're being misled by a treadmill

Do you know what airspeed is?
If I run at 20mph with a kite behind me on a piece of string, the kite will stay in the air.
What so you think happens to the kite if I'm running at 20mph on a treadmill?

 

[Deleted member 35927]

The plane has speed...the thrust from the engines provides it.
The wheels enable the plane to convert that thrust into speed
But the plane has no forward motion due to the conveyor running at the same speed.
So the plane may be doing 500 mph but its not actually moving from its original spot
Without forward motion the will be no airflow over the wings and therefore no lift.
Unless everything that's ever be said about aerodynamics is a complete falsehood the plane can't take off.
Someone could climb a ladder and hand the Pilot a beer because the plane isn't moving frommiys original location...it may be doing 500mph but it isn't travelling 500 miles in an hour.

No, incorrect the engines produce thrust which pushes the plane through the air, the wheels are of no consequence as part of theoretical point of view .

 

[Swango1980]

The plane has speed...the thrust from the engines provides it.
The wheels enable the plane to convert that thrust into speed
But the plane has no forward motion due to the conveyor running at the same speed.
So the plane may be doing 500 mph but its not actually moving from its original spot
Without forward motion the will be no airflow over the wings and therefore no lift.
Unless everything that's ever be said about aerodynamics is a complete falsehood the plane can't take off.
Someone could climb a ladder and hand the Pilot a beer because the plane isn't moving from it's original location...it may be doing 500mph but it isn't travelling 500 miles in an hour.

The wheels don't enable to the plane to convert thrust to speed.

The speed will be there. If there were no wheels, the planes fuselage would just be dragged along the ground. The wheels allow a smoother take off and landing, and avoid damage.

Absolutely no thrust is created against the ground. It is thrust against the air.

As I said, if anyone thinks the plane would be stationary on the run way, then they also need to believe that if it landed on a treadmill going the same speed in opposite direction, the plane would instantly come to rest as soon as it touched down. Like hitting a brick wall

 

[Deleted member 35927]

Do you know what airspeed is?
If I run at 20mph with a kite behind me on a piece of string, the kite will stay in the air.
What so you think happens to the kite if I'm running at 20mph on a treadmill?

Ummmm your using ground speed of your legs to power your kite through the air this is not the same.

 

[Tashyboy]

Not wanting to complicate things, but are the pilots socks ankle socks, and more importantly are they white.

 

[Deleted member 36735]

Ludicrous how ? Because you don't understand it then it's ludicrous?

Ironically, you're the one who posted it and you're the one who doesn't understand it.

Seriously, if it's a wind up then fair enough, but if not then WOW.

I'll try again for you...

Do the engines thrust a plane forward like you say?
Yes, they create a forward force and the plane moves along the runway because it's wheels allow it to roll.

Do the engines make the plane go up in the air?
No.

What do I mean?
The engines give the plane speed along the ground.

But they make it go up in the air right?
No.

What makes it go up in the air?
The wind and lift that is created by the wings travelling at high speed through the air, and obviously their design, shape, size etc.

But the engine thrust keeps the plane up in the air right?
No.
The engines propel the plane forward, the wings interact with the air as above to keep the plane up.

So why won't my plane go up in the air off the conveyor belt?
Because in the scenario given, the plane is not moving in relation to the ground so there is no air rushing under and around the wings.
Hence there is nothing making the wings do their job, the plane is just sitting on the conveyor belt with the wheels spinning at the same speed as the belt.

 

[Neilds]

Here's The Actual Science Behind That Plane Takeoff Meme You Keep Seeing - Jalopnik

A meme about whether an airplane can take off on a treadmill has been going around social media lately, tearing friendships apart with its divisiveness, ruining families and sending the world further into chaos. But now it’s time to put an end to the madness. Let’s look at the science!

jalopnik.com

https://news.ycombinator.com/item?id=726125#:~:text=It would not.,prop, jet or ion engine.

 

[Deleted member 36735]

As I said, if anyone thinks the plane would be stationary on the run way, then they also need to believe that if it landed on a treadmill going the same speed in opposite direction, the plane would instantly come to rest as soon as it touched down. Like hitting a brick wall

Assuming it doesn't skid, then obviously that is correct.
If something lands at 180mph on a surface travelling at 180mph in the opposite direction , it will of course stop immediately with no skid.

 

[RichA]

Ummmm your using ground speed of your legs to power your kite through the air this is not the same.

The kite doesn't care that my legs are on the ground. The effect would be the same if it was being towed by a tame sparrow.
Airspeed is needed to create negative pressure above the wing.

 

[Deleted member 35927]

Ironically, you're the one who posted it and you're the one who doesn't understand it.

Seriously, if it's a wind up then fair enough, but if not then WOW.

I'll try again for you...

Do the engines thrust a plane forward like you say?
Yes, they create a forward force and the plane moves along the runway because it's wheels allow it to roll.

Do the engines make the plane go up in the air?
No.

What do I mean?
The engines give the plane speed along the ground.

But they make it go up in the air right?
No.

What makes it go up in the air?
The wind and lift that is created by the wings travelling at high speed through the air, and obviously their design, shape, size etc.

But the engine thrust keeps the plane up in the air right?
No.
The engines propel the plane forward, the wings interact with the air as above to keep the plane up.

So why won't my plane go up in the air off the conveyor belt?
Because in the scenario given, the plane is not moving in relation to the ground so there is no air rushing under and around the wings.
Hence there is nothing making the wings do their job, the plane is just sitting on the conveyor belt with the wheels spinning at the same speed as the belt.

Why isn't it moving ? Youre just getting confused , it's not a wind up. Take 5 mins to read up on it.

 

[Deleted member 35927]

The kite doesn't care that my legs are on the ground. The effect would be the same if it was being towed by a tame sparrow.
Airspeed is needed to create negative pressure above the wing.

Isn't the sparrow then akin to a jet engine

 

[Deleted member 36735]

Why isn't it moving ? Youre just getting confused , it's not a wind up. Take 5 mins to read up on it.

Read what?
Some nonsense posted on the internet by a nutjob?

 

[Deleted member 35927]

Read what?
Some nonsense posted on the internet by a nutjob?

Oh dear.

 

[AmandaJR]

8 pages...

 

[3 jabber]

It's obviously yes, but I'm surprised how many try and argue otherwise.

Are you stupid or just pretending to be stupid? Read the laws of flight, lift created by airflow over curved wings etc and stop posting idiotic clickbait.

 

[Deleted member 35927]

Are you stupid or just pretending to be stupid? Read the laws of flight, lift created by airflow over curved wings etc and stop posting idiotic clickbait.

Deary me , it's an incredibly popular internet myth, I didn't make it up. I fully understand it though.

 

[Imurg]

Although Scientists are clever people a bunch of them theoretically proved that a Bumblebee shouldn't be able to fly, taking into account that it's wings are too small to keep its body airborne
This, as we all know, is a load of fertiliser.......
Theory and practice do not always walk arm in arm

 

[Fade and Die]

That is why it is a teaser, because it is easy to jump to that assumption as I did when I first read it.

But, a plane can't be stationary relative to the air, because it is thrust forward against the air. It doesn't use grund forces to propel forwards.

The plane will take off, as it is using the air, not ground, to push against.

I suppose the question to ask is that is it actually possible for the treadmill and wheels to be moving at the same speed in opposite directions? When the plane uses its engines to take off, and it accelerates down runway, the treadmill will speed up. But the wheels react to the ground and speed of plane, so they will speed up faster. Theoretically the speed of treadmill can't ever catch up with speed of wheels, because plane is always thrust forward relative to air

I think you have been led down an internet rabbit hole by a professional wum… or you are playing devils advocate (you little devil )

You are ignoring physics, the plane wing needs horizontal motion to provide lift, the OP says the treadmill somehow negates this (in spite of Pete trying to say it says something else now) no forward motion no lift. Simple stuff.

What would happen in the original scenario is the wheel bearing would overheat and disintegrate, the wheel mount would hit the treadmill that’s travelling at about 600mph and fly off the back.

 

[Deleted member 35927]

Although Scientists are clever people a bunch of them theoretically proved that a Bumblebee shouldn't be able to fly, taking into account that it's wings are too small to keep its body airborne
This, as we all know, is a load of fertiliser.......
Theory and practice do not always walk arm in arm

Ah bumblebees and flight.... Sorry my friend another internet myth along with captain pugwash