Can the plane take off?

NorCal Boater said:
Respectfully, I don't think you are getting this....
Assuming the conveyor is completely drag free and offers no resistance the plane's wheels.... if the thrust of the engines was increased to the point that resistance (gravity and drag) was overcome enough to move the aircraft, the aircraft would not move off the conveyor because as the plane began moving forward on the landing gear the conveyor would begin moving and match the speed of the wheels therefore keeping the plane in a static position. So your statement above is incorrect. Unless the plane/wheels began moving faster than the conveyor speed, at which point the plane will leave the conveyor, begin to increase speed through the air while still on the ground and then, if a speed is met that generates enough lift to make the plane fly, it will take off.

As I said before, it doesn't make any difference if the engines are running full thrust and the wheels turning faster than the speed of sound....if there isn't enough air moving over the wing surface fast enough to generate lift, the plane stays on the ground....period.

Consider a full power stall. A plane's engines can be running at full power but if the angle of attack of the wing surface in relation to the air moving over it becomes too great the wing will lose lift and the plane falls from the sky. Aircraft stalls are one of the first things you learn in pilot training.
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Haaa!

Respectfully, you don't get this!! It's not about aerodynamic stall or airfoil performance.

The conveyor wouldn't introduce sufficient drag to hold the plane stationary relative to the non-conveyor ground even if it wasn't zero drag. It is what is known in engineering as a red herring. So you said assume the conveyor is drag free. Go one more step, and using magic levitation, raise the aircraft up so the wheels don't touch the conveyor. Spin the conveyor as fast as you want, or don't. It doesn't matter.

The turbine engines act against the air. The air doesn't know about the conveyor. Neither do the engines.

How about this: Spin the conveyor at 1000MPH. Lower the aircraft onto it slowly such that the wheels spin up. If the conveyor is truly zero friction, you don't even need to touch the throttle to maintain horizontal position. Now the plane is sitting there with a conveyor zipping along under it and the wheels spinning away.

Now throttle-up, and away you go! The moving conveyor is irrelevant. It's the air that matters.

Of course, this plane has solid tires that don't explode!
 
Blueone said:
I’ve been 2 days compounding waxing a blue hull….. I come on here and you guys are 7 pages into can a plane take off from a treadmill….. maybe I just have a bad attitude :)
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It's good for the brain!
 
NorCal Boater said:
No....how could it.
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Because the engines push against the air. The air doesn't know about the conveyor. They don't care if there are tires, if there is ground, if the ground if moving forward or backward, if it's made of ice and the wheels are locked and sliding (skis, pontoons).

The engines push the plane through the air. Airspeed is all the plane knows.
 
bajturner said:
Because the engines push against the air. The air doesn't know about the conveyor. They don't care if there are tires, if there is ground, if the ground if moving forward or backward, if it's made of ice and the wheels are locked and sliding (skis, pontoons).

The engines push the plane through the air. Airspeed is all the plane knows.
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Until the wheels leave the ground it would be ground speed.

-Kevin
 
KevinC said:
Until the wheels leave the ground it would be ground speed.

-Kevin
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Groundspeed isn't typically measured on an airplane using any kind of local sensors (e.g. wheel speed) because it doesn't matter. It is calculated knowing airspeed and the speed and direction of the wind, or determined using GPS. A pitot measuring device measures airspeed and all that matters to the aircraft. Look up pitot and 737-MAX to get an idea of its importance!

Air speed and ground speed would be equivalent if there were absolutely no wind.
 
bajturner said:
Because the engines push against the air. The air doesn't know about the conveyor. They don't care if there are tires, if there is ground, if the ground if moving forward or backward, if it's made of ice and the wheels are locked and sliding (skis, pontoons).

The engines push the plane through the air. Airspeed is all the plane knows.
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Forget the plane temporarily, just look at the tire problem...
If the tires and conveyor(turning in opposite direction) are going exactly the same speed does the tire ever advance down the runway?
 
Woody said:
Forget the plane temporarily, just look at the tire problem...
If the tires and conveyor(turning in opposite direction) are going exactly the same speed does the tire ever advance down the runway?
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Do you think the plane engines are pushing the plane forward through the wheels?
 
Woody said:
Forget the plane temporarily, just look at the tire problem...
If the tires and conveyor(turning in opposite direction) are going exactly the same speed does the tire ever advance down the runway?
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To answer your question, if it were acted on by an external force (from say, a turbine engine), yes it would.

Let's try this example: You are on a regular scooter (no motor), wearing a backpack with a rocket pointing straight out the back (like turbine engines on a plane). The scooter is on a conveyor. Two friends, one on each side, not standing on the conveyor, are holding you steady. The conveyor starts and they hold you still. It's not hard to hold, because there is very little resistance pushing you backwards. The conveyor speeds up but you are still held in place. The wheels on the scooter are spinning faster and faster as the conveyor speeds up.

So now you are standing on a scooter, conveyor going, wheels spinning, friends holding you, and you light the rocket. With the huge thrust from the rocket you blast away from your friends, down the runway.

Your ground speed is the speed at which you move away from your friends.
If you had a speedometer, it would measure a speed that equals the conveyor speed + your ground speed.
If you had an air speed indicator (properly calibrated, of course), the speed it would indicate would be equivalent to your ground speed + the wind vector parallel to your direction of travel (which may result in an air speed that is higher, lower, or the same as your groundspeed).

If you added wings to your scooter, you may even take off!
 
bajturner said:
To answer your question, if it were acted on by an external force (from say, a turbine engine), yes it would.

Let's try this example: You are on a regular scooter (no motor), wearing a backpack with a rocket pointing straight out the back (like turbine engines on a plane). The scooter is on a conveyor. Two friends, one on each side, not standing on the conveyor, are holding you steady. The conveyor starts and they hold you still. It's not hard to hold, because there is very little resistance pushing you backwards. The conveyor speeds up but you are still held in place. The wheels on the scooter are spinning faster and faster as the conveyor speeds up.

So now you are standing on a scooter, conveyor going, wheels spinning, friends holding you, and you light the rocket. With the huge thrust from the rocket you blast away from your friends, down the runway.

Your ground speed is the speed at which you move away from your friends.
If you had a speedometer, it would measure a speed that equals the conveyor speed + your ground speed.
If you had an air speed indicator (properly calibrated, of course), the speed it would indicate would be equivalent to your ground speed + the wind vector parallel to your direction of travel (which may result in an air speed that is higher, lower, or the same as your groundspeed).

If you added wings to your scooter, you may even take off!
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You have to answer my tire question. The original problem had only one condition, the tire/conveyor thing. If the tires can't advance neither can the rest of the plane. The problem doesn't care about thrust, give it as much as you want....the tires ain't moving and neither is the plane.
 
Woody said:
You have to answer my tire question. The original problem had only one condition, the tire/conveyor thing. If the tires can't advance neither can the rest of the plane. The problem doesn't care about thrust, give it as much as you want....the tires ain't moving and neither is the plane.
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Well, if they have nothing pushing them or powering them, then I guess they will just fall off the end of the conveyor.

If they are frictionless with nothing pushing them, they will stay in the same place.

If they are frictionless and you add a force behind them, they will advance down the conveyor. This is the case of the airplane. As long as there is a force, they will accelerate.
 
bajturner said:
Well, if they have nothing pushing them or powering them, then I guess they will just fall off the end of the conveyor.

If they are frictionless with nothing pushing them, they will stay in the same place.

If they are frictionless and you add a force behind them, they will advance down the conveyor. This is the case of the airplane. As long as there is a force, they will accelerate.
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Let's try this maybe they will understand -
treadmill1.jpg

treadmill2.jpg

treadmill3.jpg

treadmill4.jpg
 
Stee6043 said:
Never mind all that....like I said 5 pages ago a PhD in astrophysics could stop in, provide indisputable and peer reviewed science proving the plane will fly, and half the people in this thread will still not believe it.
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I tried to keep words under three syllables.
 
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Farmboy666 said:
All that matters is airflow over the wing. That what creates lift. If it’s not moving then there’s no lift. It can sit there all day. A Cessna 172 taking off in a headwind of 50 mph has a air speed of 50 but can have a ground speed of 0 and still fly. Air speed over the wing is what counts.
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good thing there’s nothing keeping the plane from moving.
 
For those folks who say "the plane will take off"... answer this....

If the plane had to exceed the speed of light to take off, would it take off?
 
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