No
No
What's up with the free floating hostility on your posts?
Anyway, my sudden epiphany, prompted by numerous "it will fly" posts, tells me the speed of the treadmill will only affect the speed the wheels spin, the engines will propell the plane forward independently. Speed up the treadmill by ten times and the wheels will spin ten times faster but the plane will move forward at the same speed.
The fly guys were right but boy were some of their expainations long and convoluted. Short, simple, and to the point works best.
tank wrote:
Short, simple, and to the point works best.
Short, simple and to the point will only work for those of us who were thrown off by the red herring in the first place. Like me. Once it's explained, it's just trivial. As I said previously, it was designed by aeronautic types to catch out their fellow brethren who were slightly sleepy/dopey when they saw it first. It isn't really meant for the public at large. And certainly not for HS know-it-all types.
the treadmill submerged in water will electrocude you, so you will never be able to move you arms...
titan wrote:
THE ANSWER IS- IT WILL FLY
Everyone READ THIS AND PAY ATTENTION!!!!
Imagine your in a pool standing in water up to your chin on a treadmill. You are walking on the treadmill in the water. Your feet are pushing against the surface of the TM. NOW, you start to move your arms (jet engines) in a swimming motion while still on the treadmill. If you do this vigorously enough you WILL sart to move relative to the water and the ground, your feet(wheels)satrt to slide across the surface of the TM no matter how fast the TM is turning against you. You will be moving in a horizontal direction. Hypothetically if you keep accelerating (moving your arms-jets) fast enough you would gain enough speed to create enough pressure (air) under wings to get lift in the verticle direction.
You can think of water as denser air because it behaves the same way physically
tank wrote:
What's up with the free floating hostility on your posts?
Yes, it's true that I am a little bit hostile, but man, it just irks the shit out of me when people use pen names like "actual aerospace guy" and "one smart motherfocker" and are COMPLETELY wrong.
Like I said before, if a real "aerospace guy" can't comprehend this simple riddle, then God help us all when we're strapped in to the contraption he designed.
I'm being serious with this question, so flame away... There's something I can't understand about the "no fly" people. There argument is that there will be no wind to create lift. Help me out with this. If I'm piloting a plane and "driving it" 200 MPH (with a treadmill going 200 MPH's in the other direction) and I stick my hand out the window- are you people trying to tell me that my hand won't be pushed backwards?
I think I understand where the "no fly" people are coming from.
You put a rollerskate on a treadmill and it flies backward, right? Why? Because the wheels aren't exactly free spinning, there is some rolling resistance. The resistance is small, and it doesn't take much force going in the opposite direction to overcome it, so the "it will fly" people don't think it is important.
However, if the treadmill is going fast enough, that rolling resistance will come back into play. Someone said earlier that the treadmill can be going an infinite speed and it won't matter because the wheels will just spin freely. That's incorrect. At high enough speeds the rolling resistance becomes a factor again.
In order for the rolling resistance to become a factor, however, the difference between the speeds of the treadmill and jet have to be significant. Something on the order of - the jet engines are pushing the jet forward at 30 mph and the treadmill is moving backward at 2,000 mph. Some big difference like that. At that point, the forces will be equal and it will stay still.
I think the "no fly" people are thinking of the FORCES being equal (like above). The "it will fly" people are thinking of the SPEEDS being equal (30 mph jet thrust vs. 30 mph treadmill). And both groups are correct. If the forces equal out, it won't fly. But if we're talking speeds (like in the riddle), it will fly.
Ex- Thrower wrote:
I'm being serious with this question, so flame away... There's something I can't understand about the "no fly" people. There argument is that there will be no wind to create lift. Help me out with this. If I'm piloting a plane and "driving it" 200 MPH (with a treadmill going 200 MPH's in the other direction) and I stick my hand out the window- are you people trying to tell me that my hand won't be pushed backwards?
Easy. The treadmill isn't moving, the belt is moving.
If you put the treadmill in the back of a pickup truck and drove 150 mph the airplane would lift.
If you stop the pickup truck and set the jet engine at 10mph force, with the belt of the treadmill rotating at 150 mph, the airplane would run off the back end of the treadmill at 140 mph, then remain at that end of the belt.
Bump the thrust of the airplane to 50mph, it runs off the back end of the treadmill at 100 mph, where it will remain at the end of the belt.
Bump the trust to 100 mph, it run off the back end of the treadmill at 50 mph where it will remain.
At 150 mph thrust, the airplane is stationary.
At "one tiny increment" above 150 mph thrust, the airplane will not fly, but it will be traveling at "one tiny increment" above 0 mph off the front of the treadmill, where it will then accelerate (provided enough runway) until it reaches 150mph and flys.
At 200 mph thrust, the airplane will shoot off the FRONT of the treadmill at 50 mph. IT WILL NOT FLY. If there is enough room (runwawy) in front of the treadmill it will accelerate from 50mph until it reaches 150 mph, where it will then fly.
It will never leave the treadmill "in flight." The airplane will have to accelerate ON SOLID GROUND, before it gets enough velocity to have sufficient lift to fly.
I think I've figured it out wrote:
I think I understand where the "no fly" people are coming from.
You put a rollerskate on a treadmill and it flies backward, right? Why? Because the wheels aren't exactly free spinning, there is some rolling resistance. The resistance is small, and it doesn't take much force going in the opposite direction to overcome it, so the "it will fly" people don't think it is important.
However, if the treadmill is going fast enough, that rolling resistance will come back into play. Someone said earlier that the treadmill can be going an infinite speed and it won't matter because the wheels will just spin freely. That's incorrect. At high enough speeds the rolling resistance becomes a factor again.
In order for the rolling resistance to become a factor, however, the difference between the speeds of the treadmill and jet have to be significant. Something on the order of - the jet engines are pushing the jet forward at 30 mph and the treadmill is moving backward at 2,000 mph. Some big difference like that. At that point, the forces will be equal and it will stay still.
I think the "no fly" people are thinking of the FORCES being equal (like above). The "it will fly" people are thinking of the SPEEDS being equal (30 mph jet thrust vs. 30 mph treadmill). And both groups are correct. If the forces equal out, it won't fly. But if we're talking speeds (like in the riddle), it will fly.
this sounds right
You saw it clearly fairly early.
Its a theoretical thought experiment designed to tease out a concept, but people get bogged down about tangental issues such as friction, how powerful a jet engine is, is gets a bit crazy.
Holiday Inn Express wrote:
Easy. The treadmill isn't moving, the belt is moving.
If you put the treadmill in the back of a pickup truck and drove 150 mph the airplane would lift.
If you stop the pickup truck and set the jet engine at 10mph force, with the belt of the treadmill rotating at 150 mph, the airplane would run off the back end of the treadmill at 140 mph, then remain at that end of the belt.
Bump the thrust of the airplane to 50mph, it runs off the back end of the treadmill at 100 mph, where it will remain at the end of the belt.
Bump the trust to 100 mph, it run off the back end of the treadmill at 50 mph where it will remain.
At 150 mph thrust, the airplane is stationary.
At "one tiny increment" above 150 mph thrust, the airplane will not fly, but it will be traveling at "one tiny increment" above 0 mph off the front of the treadmill, where it will then accelerate (provided enough runway) until it reaches 150mph and flys.
At 200 mph thrust, the airplane will shoot off the FRONT of the treadmill at 50 mph. IT WILL NOT FLY. If there is enough room (runwawy) in front of the treadmill it will accelerate from 50mph until it reaches 150 mph, where it will then fly.
It will never leave the treadmill "in flight." The airplane will have to accelerate ON SOLID GROUND, before it gets enough velocity to have sufficient lift to fly.
Just shut up. You're wrong. Please just shut up so I can quit checking this thread. Please.
Hold on, let's forget about real world for now and simplify it because this really annoys me so many people can't figure this out.
1) Pretend no friction. Plane doesn't fly, can we agree on that?
2) Now friction exists, we are assuming the plane is stationary right? So the treadmill belt is moving backwards at exactly the same speed as the airplane. So the plane is still stationary. Right? Let's go from there.
I will need a powerpoint presentation to accurately explain why the plane will not take off.
If the plane was piloted by Jason Rexing it will take off.
What does electrocude mean?
physics major wrote:
Hold on, let's forget about real world for now and simplify it because this really annoys me so many people can't figure this out.
1) Pretend no friction. Plane doesn't fly, can we agree on that?
2) Now friction exists, we are assuming the plane is stationary right? So the treadmill belt is moving backwards at exactly the same speed as the airplane. So the plane is still stationary. Right? Let's go from there.
1) No, we don't agree. If there's no friction, then essentially the plane is hovering over the treadmill. Turn on the engines and away you go. It flies.
2) You have to explain more. It's stationary if the treadmill isn't moving and engines are off.
See my explanation above for the difference between the FORCE being equal versus the SPEED being equal for my take on this situation.
"I think I figured it out", how about this?
If the plane is stationary on the treadmill (speed is equal, not force) then the plane is moving at 0 mph, so now the plane takes off. When it lifts off the treadmill it is now still going 0 mph, how then does it still fly without a speed of 150 mph? If it could take off there would be a discontinous jump in speed for it to fly. Can you explain that to me?
I would like to see why people think it would take off.
and by stationary I mean the plane is moving forward 150 miles an hour and the treadmill is moving backwards at 150 miles per hour. The jets/propellor can be on or off, whatever you want. I guess you could say the wheels are moving 150 miles per hour.
you still need to jump from 0 mph to 150 mph to keep the plane in the air.
With no friction, the plane doesn't hover, it rolls.
physics major wrote:
"I think I figured it out", how about this?
If the plane is stationary on the treadmill (speed is equal, not force) then the plane is moving at 0 mph, so now the plane takes off. When it lifts off the treadmill it is now still going 0 mph, how then does it still fly without a speed of 150 mph? If it could take off there would be a discontinous jump in speed for it to fly. Can you explain that to me?
I would like to see why people think it would take off.
No, you're still mixing up speed and force.
I can't even make it to the end of your first parenthesis because what you're saying is incorrect. If the plane is stationary on the treadmill (meaning the treadmill is moving and the engines are on, but the two cancel each other out), the speed of the treadmill and the speed of the plane will not be equal.
fred the dog wrote:
If the plane was piloted by Jason Rexing it will take off.
Only if Chuck Norris is not holding one of the tires.
It will fly. This is an excellent picture of why it will fly.