Can the plane take off?

fellas we have went from jumping on ramps to faking space walking, damn I love it here.
thank you Stee!
 
jmauld said:
Because the wheels on the conveyor have just as much to do with the plane taking off as trying to use them to stop while in the air.

let’s try a different approach. When the plane lands, the wheels are not moving at touch-down. Why doesn’t the plane come to an immediate stop?
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You still are gonna pin your hopes to the mythical chuckleheads driving at the EXACT SPEED at every millisecond to match the question????
Even if I thought it would work, ANY deviation in speed renders results invalid to OP’s hypothesis.
 
Great Lakes said:
If the wheels move one foot forward then the plane moves one foot forward, correct? What if the wheels can’t move one foot forward because the treadmill won’t allow them to. Regardless of the thrust of the plane or the friction of the bearings, etc. The question states it matches the speed. Then the plane can’t move one foot forward either which means no lift.

Now..I think both sides can be correct because the way the question is written.

The no take off crowd reads the question as is. Does not take into account any other factors.

The take off crowd looks past the question and applies knowledge and most likely real world physics.
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The treadmill doesn't prevent the wheels from moving forward.
 
LTD.330 said:
I agree there are some profound misunderstandings going on.

Back to the plane at the end of the runway, brakes on, and at full power. Why doesn't the plane take off? Because the brakes are on and not allowing any forward movement from the thrust. Can we agree on that?

For a plane to take off, the brakes would be released, the plane would roll down the runway, gaining speed, from 0 MPH until there was enough air speed to create lift. All of the thrust produced at this point is acting directly on the wheels. Removing the brakes doesn't instantly mean the plane is flying due to the thrust from the engines. Can we agree on this?

The original problem stated the conveyor would match the wheel speed in the opposite direction. That means the wheels can't turn faster than the conveyor is moving, which by definition means the plane isn't going to cover any ground. Airspeed and lift never enters the equation because the plane remains stationary.
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Regarding your statement: "All of the thrust produced at this point is acting directly on the wheels."

This is the source of your confusion. Only a small portion of the thrust is acting on the wheels...just enough to negate friction in the wheels and tires. All the remaining thrust, lots of it, causes acceleration and acts against the growing force of drag. The wheels just spin at the speed dictated by the moving treadmill plus the forward motion of the aircraft.

It's that simple.
 
bajturner said:
Regarding your statement: "All of the thrust produced at this point is acting directly on the wheels."

This is the source of your confusion. Only a small portion of the thrust is acting on the wheels...just enough to negate friction in the wheels and tires. All the remaining thrust, lots of it, causes acceleration and acts against the growing force of drag. The wheels just spin at the speed dictated by the moving treadmill plus the forward motion of the aircraft.

It's that simple.
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This makes a lot of sense. Might have moved me a bit
 
Why ?…. Why?…. Did you guys all miss plane 101 in school ?

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Woody said:
.... but the one and only condition of the problem does. You smart guys are hung up, it's a plane, there's thrust, there's lift, it's got to fly damn it.

But it can't if it's wheels aren't allowed to advance down the runway.
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It doesn't say that. The condition is "The conveyor belt is designed to match the speed of the wheels, in the opposite direction". Again, who cares what the wheels are doing. The wheels can go fast or slow or forwards or backwards it doesn't matter' they do not inhibit the body and wings from going backwards or forwards. The Only thing the conveyor does is speed up or slow down the wheels.

So in this case the conveyor moves the same direction as the airplane moving down the "runway" which counters the rotation of the wheels. Matching the speed of the wheels the conveyor will be the same speed as the aircraft moving down the runway and will completely stop the wheel rotation.
BUT, the aircraft is moving down the conveyor at the same speed as the conveyor (coincidently as the two have nothing to do with each other) and it takes off.

Hold it - you are messing with me right?
 
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Woody said:
.... but the one and only condition of the problem does. You smart guys are hung up, it's a plane, there's thrust, there's lift, it's got to fly damn it.

But it can't if it's wheels aren't allowed to advance down the runway.
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The problem doesn't state the wheels can't advance. It states the treadmill matches the wheel speed in the opposite direction (which was identified as a control feedback impossibility, and assumed to mean the equivalent, opposite speed of the aircraft).

Regardless of the speed of the treadmill, it doesn't stop the plane from moving forward.

As in other examples given, could you pull a wagon off the front of a moving treadmill. Of course you can!
 
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