Throwback thread
- Thread starter clonehenge
- Start date
I'm gonna wait for Steve Leath to weigh in.
Yes, the engines do that, pulling the air through to create the lift. The wheels are independent from the engines. The only difference a treadmill makes is that they'll just be rotating faster.
I'll just dip into my bottomless Greater University Fund to pay off those that are displeased.
Also, this thread, which I think was first.
Plane on a Treadmill
As we're all internet forum addicts... I'm sure we've heard of the "Plane on a Treadmill" puzzle. And just to summarize - the question is, if a plane is on an infinitely long treadmill that is capable of accelerating to match the speed of the plane, will the plane take off? There's no official...
cyclonefanatic.com
The plane was clearly moving forward so obviously the speeds did NOT match. Not a valid experiment.
If the plane is taxiing at 20 mph on pavement and then hits the end of a treadmill going 10 mph in the opposite direction, how fast will the plane be going as it travels along the treadmill? The answer is 20 mph because plane wheels spin free and are not used to propel the plane forward. A car would slow to 10 mph because it does use the wheels to power forward motion. In the original problem the treadmill could be going a thousand miles an hour and the plane would take off just fine. In real life of course the wheels would blow up long before they could spin that fast but the point remains that the treadmill is irrelevant.
I thought planes got thrust from the engines, but lift from the wings. Hence, a plane on a treadmill won't take off.
The whole point is that a treadmill can’t stop (or even slow down) a plane from moving forward no matter how fast the treadmill is going. If you can’t stop the plane from moving forward you can’t stop the plane from taking off.
Say a plane is on a runway and the runway is painted bright red. The color becomes darker the faster the plane moves. Will the plane take off? Of course it will because the color of the runway doesn’t matter just like the presence of a treadmill doesn’t matter.
I think you're assuming the plane was moving before getting on the treadmill, though - is that said anywhere? I read it as a stopped plane is on a treadmill, and as it accelerates, the treadmill accelerates at the same speed in the opposite direction. So the plane is never actually moving/advancing forward?
But I don’t think that matters because the wheels are just there to hold the plane up, not move it.
Agree. After reading through @ricochet original (and thoughtful) response it dawned on me to consider a float plane. No wheels needed - the plane's engine "pulls" the plane forward "dragging" the floats along the surface of the water, similar idea (at least in my mind's eye) to "dragging" the wheels along the counteracting conveyor.
For anyone thinking the plane doesn't fly, you need to realize that a plane on the ground does not work like a car. A car propels itself forward by using an engine that turns the wheels which grip and push forward on the road.
A plane moves by pushing air through the engines, pushing it out the back creating thrust. The wheels spin freely, they are just there to keep the body from scraping the ground.
Just think about this, if you needed the wheels to push and accelerate the plane down the runway at takeoff, what happens as soon as you get off the ground? Of the wheels were driving the plane, you would lose speed as soon as you lost contact with the runway and would quickly come back down.
A plane moves by pushing air through the engines, pushing it out the back creating thrust. The wheels spin freely, they are just there to keep the body from scraping the ground.
Just think about this, if you needed the wheels to push and accelerate the plane down the runway at takeoff, what happens as soon as you get off the ground? Of the wheels were driving the plane, you would lose speed as soon as you lost contact with the runway and would quickly come back down.
