COULD A PLANE TAKE OFF FROM A CONVEYER BELT? - PLEASE READ

[shinny]

I thought velocity was 0 since the conveyor belt was moving at an equal speed but opposite direction to the plane (hence no net movement)? It's just like a person on a treadmill isn't it? They can run for an hour but their displacement hasn't changed (i.e. 0), so their velocity (displacement/time) should be 0.

Depends upon the frame of reference.  The plane is obviously moving in some frame of reference, because its moving!  Clearly in the correct frame, it will have momentum. 

I don't really understand what you mean by frame of reference (nor do I get how my logic is flawed at at least a mathematical level), but having no physics background at all, I'll just shuddup from here on and see how this turns out. Don't think there's any point trying to discuss against aerospace engineers and others in this topic with my elementary knowledge of spesh vectors and dynamics =="

[dcc]

I don't really understand what you mean by frame of reference (nor do I get how my logic is flawed at at least a mathematical level), but having no physics background at all, I'll just shuddup from here on and see how this turns out. Don't think there's any point trying to discuss against aerospace engineers and others in this topic with my elementary knowledge of spesh vectors and dynamics =="

Basically, if you are on a train, and you throw a ball up, you are considering the motion of the ball relative to the train, rather then the ground outside.  If you were looking at the speed relative to the ground, you'd find the , which gets very confusing.

[shinny]

I don't see how that's relevant to this problem though, but bleh don't mind me. I don't want this thread just becoming a physics lesson for me; let the discussion continue guys~

[dcc]

I don't see how that's relevant to this problem though, but bleh don't mind me. I don't want this thread just becoming a physics lesson for me; let the discussion continue guys~

The plane is rolling, there is some motion occuring.  It will have momentum!

[Cthulhu]

Hold up.

Is the conveyor belt moving in the same direction as the plane but opposite direction of the wheels? This changes everything if it is.

[dcc]

Hold up.

Is the conveyor belt moving in the same direction as the plane but opposite direction of the wheels? This changes everything if it is.

Imagine the plane is on a really large exercise machine.

[dejan91]

I believe it will NOT. As far as I know, a plane is able to take off due to the wind resistance/drag pushing up on its wings and body. On a conveyer belt, the only moving parts are the wheels, not the plane itself. There is therefore no wind to 'push' it up, so no, no chance it will take off.

It's like saying is an F1 car is areodynamic on a conveyer belt.... sure it has the parts to make it areodynamic, but on a conveyer belt it's not because the downforce and what not isn't present to due lack of wind/air drag.

EDIT: In regards to the 'momentum' of the plane. From a frame of reference from a stationary point on the conveyer belt, the pane has momentum (I think?). but from a point of reference inside the plane or next to it, the plane has no momentum - the conveyer belt on the other hand does.

[shinny]

EDIT: In regards to the 'momentum' of the plane. From a frame of reference from a stationary point on the conveyer belt, the pane has momentum (I think?). but from a point of reference inside the plane or next to it, the plane has no momentum - the conveyer belt on the other hand does.

That's what I was thinking. The wind force is relative to the ground, not the conveyer belt (as the wind's velocity is unaffected by the conveyer belt), and I'd always assumed the ground to be my frame of reference because of that. I understood what you meant after since of course, if you jumped on the conveyer belt, the plane clearly has momentum since you'd get quite a nice whacking as you get dragged down the conveyer belt into the plane, but I just don't see the relevance of measuring from the conveyer belt. Without a momentum RELATIVE TO THE GROUND, I don't see how it could fly.

EDIT: Dammit why'd I step in again. Totally gonna get torn apart.

[Glockmeister]

The plane will fly.

What determine whether a plane can fly isn't the ground speed of the aircraft, but the lift generated by the wings.

[dejan91]

lift generated by the wings.

Which comes from where exactly?

[shinny]

The plane will fly.

What determine whether a plane can fly isn't the ground speed of the aircraft, but the lift generated by the wings.

But it has to fly into the wind to create the lift in the first place? It's not moving relative to the ground as I first stated.

EDIT: Beaten by dejan

[Glockmeister]

lift generated by the wings.

Which comes from where exactly?

power generated by the engine.

[enwiabe]

The plane will fly.

What determine whether a plane can fly isn't the ground speed of the aircraft, but the lift generated by the wings.

But lift depends on the airflow speed over the wing. Will the treadmill allow the plane to build up a significant flow over the wing to generate a sufficient adverse pressure gradient to generate enough lift to get the plane off the ground?

That is the whole reason for a plane's sprint down the runway. To create a freestream velocity that will generate enough lift to get the plane into the air...

Perhaps you should not be authoritatively commenting on things on which you are not an authority!

Note, I offer my post above as a conjecture only, and do not claim its contents to be entirely valid.

[Glockmeister]

The plane will fly.

What determine whether a plane can fly isn't the ground speed of the aircraft, but the lift generated by the wings.

But lift depends on the airflow speed over the wing. Will the treadmill allow the plane to build up a significant flow over the wing to generate a sufficient adverse pressure gradient to generate enough lift to get the plane off the ground?

That is the whole reason for a plane's sprint down the runway. To create a freestream velocity that will generate enough lift to get the plane into the air...

Perhaps you should not be authoritatively commenting on things on which you are not an authority!

Note, I offer my post above as a conjecture only, and do not claim its contents to be entirely valid.

Answer to your question. Yes. Why? Because the wheels are irrelevant as the thrust is generated by the engines an the propeller, not the wheels.  

I'll cite my source tomorrow.

NB: When I have the time and money, I'm hoping to get my PPL (Private Pilot's Licence). Right now, I'm at 20 or so hours of flight time.

[enwiabe]

The plane will fly.

What determine whether a plane can fly isn't the ground speed of the aircraft, but the lift generated by the wings.

But lift depends on the airflow speed over the wing. Will the treadmill allow the plane to build up a significant flow over the wing to generate a sufficient adverse pressure gradient to generate enough lift to get the plane off the ground?

That is the whole reason for a plane's sprint down the runway. To create a freestream velocity that will generate enough lift to get the plane into the air...

Perhaps you should not be authoritatively commenting on things on which you are not an authority!

Note, I offer my post above as a conjecture only, and do not claim its contents to be entirely valid.

Answer to your question. Yes. Why? Because the wheels are irrelevant as the thrust is generated by the engines an the propeller, not the wheels.  

I'll cite my source tomorrow.

NB: When I have the time and money, I'm hoping to get my PPL (Private Pilot's Licence). Right now, I'm at 20 or so hours of flight time.

As far as I am aware, a boeing 747 has no propeller.

And yes, the wheels do matter. The thrust can create all the power it wants. If the conveyor belt is matching the translational motion of the plane, then the plane is stationary relative to the air around it. Not enough wind going over the plane's wings -> no lift.