Plane

[Deleted member 35927]

Yes, you could. But do you think the standard engines on a 747 would provide enough thrust to make it move if it was sat on pads?

I'm not sure of your point. The question is in the op and the answer is yes.

 

[SteveW86]

Here's a clue to the answer:

If it was a car on the conveyor belt then the car speedo would read whatever the belt is doing.

Substitute car for aircraft and the Air Speed Indicator in the cockpit would read zero. Aircraft simply don't give a hoot about wheel speed.

Agree with this.

Im no aero engineer or such, but for me if the plane is stationary then there is no lift being created by the wings, so it would stay on the ground.

Can have as much airflow going through the engine as you like.

 

[Deleted member 35927]

Here's a clue to the answer:

If it was a car on the conveyor belt then the car speedo would read whatever the belt is doing.

Substitute car for aircraft and the Air Speed Indicator in the cockpit would read zero.

Agree with this.

Im no aero engineer or such, but for me if the plane is stationary then there is no lift being created by the wings, so it would stay on the ground.

Can have as much airflow going through the engine as you like.

And where does that airflow go what's the result of it, that force has go somewhere .
Think laws of motion

 

[SteveW86]

And where does that airflow go what's the result of it, that force has go somewhere .

It gets fired out the back of the engine.

You seem to be doing a lot of arguing, but not actually explaining anything. .

normally, the force would push the plane forwards and you’d get airflow over the wings, creating lift and the plane would take off.

But on the treadmill the force pushing the plane forwards is balanced by the treadmill so the plane doesn’t ever move and you don’t get the flow over the wings (you only get the flow into and out of the engine).

I’m happy to be wrong if you can explain why, rather than just saying you’re wrong

 

[Arthur Wedge]

The 747 on the conveyor belt dilemma solved with Simcenter Amesim | Bsim Engineering

bsim-engineering.com

 

[Bunkermagnet]

It gets fired out the back of the engine.

You seem to be doing a lot of arguing, but not actually explaining anything. .

normally, the force would push the plane forwards and you’d get airflow over the wings, creating lift and the plane would take off.

But on the treadmill the force pushing the plane forwards is balanced by the treadmill so the plane doesn’t ever move and you don’t get the flow over the wings (you only get the flow into and out of the engine).

I’m happy to be wrong if you can explain why, rather than just saying you’re wrong

It seems he's ignoring Newton's third law.

 

[Deleted member 36735]

Could a long-jumper run on a treadmill as fast as they normally do and then jump as far as they normally do relative to the fixed floor?
No, of course they couldn't because if they were running fast on a treadmill they only have forward movement relative to the belt, not the real floor.

The "movement" of the plane on the treadmill is exactly the same, it's forward at speed relative to the treadmill only. There's no air flowing under and around the plane, the force from the engines is offset by the rolling of the wheels and the plane doesn't move relative to the planet hence it would never take off.

 

[Hazard]

And where does that airflow go what's the result of it, that force has go somewhere .
Think laws of motion

I think you are confusing 2 separate things, thrust and lift. True that for every action there is an equal and opposite.. etc, etc but you need both to fly (or take-off, even)

So here's a question for you... why do aircraft have wings?

 

[Deleted member 35927]

Could a long-jumper run on a treadmill as fast as they normally do and then jump as far as they normally do relative to the fixed floor?
No, of course they couldn't because if they were running fast on a treadmill they only have forward movement relative to the belt, not the real floor.

The "movement" of the plane on the treadmill is exactly the same, it's forward at speed relative to the treadmill only. There's no air flowing under and around the plane, the force from the engines is offset by the rolling of the wheels and the plane doesn't move relative to the planet hence it would never take off.

This is a very strange take, planes have jets that interact with the air, not legs that interact with the ground.

 

[Fade and Die]

View attachment 56870

Another thing on this, the conveyor belt is programmed to match the speed of the wheels, but the wheels are not powered so how does the conveyor belt move?

Btw top darts for a Sunday morning

 

[Deleted member 36735]

This is a very strange take, planes have jets that interact with the air, not legs that interact with the ground.

They also need speed relative to the ground.

 

[Deleted member 35927]

It seems he's ignoring Newton's third law.

Yes you are

 

[Deleted member 35927]

They also need speed relative to the ground.

Yes and how do they get that speed,

 

[IanM]

I guess if you jump up in the air in a train doing 125mph, you smash into the wall behind you at 125mph!

 

[SteveW86]

I guess if you jump up in the air in a train doing 125mph, you smash into the wall behind you at 125mph!

The train is moving, the plane isn’t.

Is this why urinals on trains face backwards, so you don’t piss on yourself?

 

[IanM]

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

Regardless, a cracking example (on many levels) of everything that is wrong with the forum these days.

 

[IanM]

Someone will still say YAW wrong

 

[Hazard]

They also need speed relative to the ground.

Not quite true, they actually need speed relative to the air.

@Hamburgerpete - can you answer my question as to why aircraft have wings?

 

[Deleted member 35927]

Regardless, a cracking example (on many levels) of everything that is wring with the forum these days.

A lack of physics knowledge?

 

[Deleted member 35927]

Not quite true, they actually need speed relative to the air.

@Hamburgerpete - can you answer my question as to why aircraft have wings?

Nice place to put the engines also handy for generating lift.