Pop quiz: could a plane on a giant treadmill take off?

If the treadmill was fast enough, wouldn't the plane not be moving at all, and therefore unable to generate lift?

Get out of this thread with your intellectual snobbery. Damned elitist high school graduates...
 
Yes. Treadmill doesn't matter since the wheels are free spinning.
 
if the plane moves along the treadmill it will generate lift and take off. if it stays in the same spot relative to the ground with the wheels spinning in place it wont create lift and it will not take off. edit. apparently it can be done with optimal conditions.
 
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Is the plane front or rear wheel driven?
 
Wings can't generate lift without significant amounts of downward-forced air, right? So, wouldn't you need a wind tunnel for this to be successful? Without it, where's the necessary amount of air coming from to generate the downforce required for lift?

Important note: I am not a scientist.
 
Not sure why the treadmill is long as opposed to just the length of the plane?

Is the plane moving along the treadmill with the treadmill just acting to eat up the distance needed to take off. IF the plane is moving along the treadmill then yes the distance to take off would be shortened immensely. However if the treadmill is creating neutral or no physical distance movement and the plane can simply accelerate to its take off speed, I would say that the plane will be missing the other key element for take off which is wind sheer across the wings to create lift and thus no it would not be able to take off.
 
The 5 mile treadmill would be long enough to get up to speed.

Getting up to speed is not the only issue.

A treadmill the planes length would allow it to get up to the speed or rpm's necessary if it matched the tire rotation perfectly. But that would not generate the lift as there would be no airflow over the wings.

You would need a treadmill that was slower then the planes take off speed so the plane would be moving on it to obtain the necessary air flow over the wings.
 
The answer is no.


How the fuck are you supposed to get a 747 inside a gym?
 
Getting up to speed is not the only issue.

A treadmill the planes length would allow it to get up to the speed or rpm's necessary if it matched the tire rotation perfectly. But that would not generate the lift as there would be no airflow over the wings.

You would need a treadmill that was slower then the planes take off speed so the plane would be moving on it to obtain the necessary air flow over the wings.

I realize that. But the question was for a 5 mile long treadmill. So the planes wheels would be spinning at around 225-255 mph before take off in the op's scenario.
 
Getting up to speed is not the only issue.

A treadmill the planes length would allow it to get up to the speed or rpm's necessary if it matched the tire rotation perfectly. But that would not generate the lift as there would be no airflow over the wings.

You would need a treadmill that was slower then the planes take off speed so the plane would be moving on it to obtain the necessary air flow over the wings.

No. The speed of the treadmill is not counteracting the forward momentum of the plane, as the plane is not propelled forward by the wheels, but by the jet engines.

It doesn't matter how fast the treadmill is moving opposite to the plane. The plane's wheel rotation is only affected.
 
Not reading any posts, but just think about your question.

"Will spinning the wheels on a stationary plane make it somewhow rise into the sky?"

The answer is no. It takes lift, generated by passing air over the wings, to make a plane fly. Not picking on you TS, but this is an incredibly dumb question.

You didn't understand the question, dummy.
 
Holy Christ.

The airplane's engines do not act on the wheels. They act only on the airplane. The wheels are essentially a lubricant. Therefore, the airplane will accelerate normally, because the treadmill acts only on the wheels. The length of the treadmill only matters in that the airplane still needs the runway space to get into the air. It will not shorten the takeoff distance.
 
I think the plane would take off like normal, the wheels, which aren't connected to a drive train like they are with a car, would just be spinning an extra 75mph over normal takeoff speed while the velocity of the plane itself would be what it is normally. Thus, normal air moving under wings and normal lift for takeoff. The only effect might be some slight initial resistance from the rolling friction, but the thrust of a jet liner could easily overcome that.

Think of it this way... If you put a bicycle on this treadmill, then you would have no chance of riding it since the back wheel which is connected to the treadmill is required for propulsion. At 75mph you'd actually eat sh*t pretty bad. However, if you left the bicycle on the treadmill but you were standing off to the side of the treadmill holding onto it, you could easily push it forward at whatever speed you wanted to walk/run, because now the wheels are spinning freely and the propulsion system (you) isn't connected to the treadmill... the wheels would just be spinning really fast.

I'm quoting this because your example should be simple enough for people to understand why the plane will take off. At least I hope so.
 
So why don't we have all planes on treadmills, to save space

How about it, science ?
Because the plaine doesn't care if it's a moving treadmill or solid tarmac as soon as it starts moving. It still needs the distance through the air.

If you are driving your car at 100mph and a fly on your dash decides to take off, do you think it will go crash on the back window because the car is going so fast? Of course not. The fly is simply moving relative to the air around it.

The only extra force the airplane has to overcome is the bearing friction of the wheels spinning. Which it would easily be able to.
 
So, in reading about this, the boiled-down answer appears to be that the airplane requires sufficient thrust to overcome the friction of the wheels against the treadmill, and then sufficient force to propel the airplane through the air in such a way that the wings generate enough lift to get the plane off the ground. Assuming that the combination of those thrusts is less than the maximum generated thrust of the airplane (according to lots of people who have answered this question, it absolutely is less than the maximum), then it would take off.

Apparently the treadmill can run up to unreasonably high speeds and the plane will still take off, pending the structural integrity of the landing gear. I don't know enough about rubber or axles to comment.
 
I am a bit surprised by how many people didn't realize me asking why we don't replace runways with treadmills ... was a joke. I figured the "How about it, science ?" was a dead giveaway
 
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