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AZKC
12-07-2007, 06:41 AM
Q: Will an airplane on a treadmill be able to takeoff? ( No Answer, 81 Comments )
[More Theories (http://answers.google.com/answers/threadview?id=428718)

HCS
12-07-2007, 06:45 AM
If you don't rope it down it will fly. :rolleyes:

Jetaholic
12-07-2007, 06:47 AM
Q: Will an airplane on a treadmill be able to takeoff? ( No Answer, 81 Comments )
[More Theories (http://answers.google.com/answers/threadview?id=428718)
OK...let's end this once and for all.
The question stated that the treadmill has a speed tracking system on it that tracks the plane's speed, and adjusts its speed to match the plane's speed but in the opposite direction. Basically what this system does is adjusts the treadmill speed so that all forward movement of the plane is cancelled out. No forward movement of the plane = no airflow over the wings = no lift generated = plane will not take off.
Now if the plane's liftoff speed was say...100 knots...and the treadmill was fixed at that speed...the plane will take off...but would have to generate twice the thrust it would have to generate if it were on a non moving runway, and the wheels would be spinning twice as fast.

uvindex
12-07-2007, 06:53 AM
OK...let's end this once and for all.That's a good one. :)
Basically what this system does is adjusts the treadmill speed so that all forward movement of the plane is cancelled out.You must be using a wheel-driven aircraft. (Where did you get such a thing anyway??)

Jetaholic
12-07-2007, 06:58 AM
That's a good one. :)
You must be using a wheel-driven aircraft. (Where did you get such a thing anyway??)
Wheel driven? Where did you get that from?
It doesn't track the speed of the wheels...it tracks the speed of the aircraft itself. The speed of the wheels is irrelevant.

snake321
12-07-2007, 07:03 AM
Didn't state whether it was facing into the wind or not.......

LUVNLIFE
12-07-2007, 07:11 AM
OK...let's end this once and for all.
The question stated that the treadmill has a speed tracking system on it that tracks the plane's speed, and adjusts its speed to match the plane's speed but in the opposite direction. Basically what this system does is adjusts the treadmill speed so that all forward movement of the plane is cancelled out. No forward movement of the plane = no airflow over the wings = no lift generated = plane will not take off.
Now if the plane's liftoff speed was say...100 knots...and the treadmill was fixed at that speed...the plane will take off...but would have to generate twice the thrust it would have to generate if it were on a non moving runway, and the wheels would be spinning twice as fast.
YES, YES, YES:)

uvindex
12-07-2007, 07:14 AM
Wheel driven? Where did you get that from?Since you think the treadmill cancels out the speed of the aircraft, one can only assume that you think the airplane is driven by its wheels.

Miss Perfect
12-07-2007, 07:18 AM
OMG...are we really doing this again?!?!?!?!?

Jetaholic
12-07-2007, 07:25 AM
Since you think the treadmill cancels out the speed of the aircraft, one can only assume that you think the airplane is driven by its wheels.
By "speed of the aircraft" I am referring to the forward movement of the aircraft's fuselage...not the speed of the wheels.

uvindex
12-07-2007, 07:31 AM
By "speed of the aircraft" I am referring to the forward movement of the aircraft's fuselage...not the speed of the wheels.That's my definition of speed of the aircraft too.

Jetaholic
12-07-2007, 07:39 AM
That's my definition of speed of the aircraft too.
Right...well the treadmill tracks the movement of the aircraft's fuselage...and adjusts its speed to cancel out all forward movement of the aircraft's fuselage...however fast it has to go to do so.

uvindex
12-07-2007, 07:44 AM
Right...well the treadmill tracks the movement of the aircraft's fuselage...and adjusts its speed to cancel out all forward movement of the aircraft's fuselage...however fast it has to go to do so.The aircraft's wheels are free-wheeling, right? Why do you think that an aircraft's speed can be canceled or otherwise influenced simply by applying force to its free-wheeling wheels?? :)

Ziggy
12-07-2007, 11:15 AM
The aircraft's wheels are free-wheeling, right? Why do you think that an aircraft's speed can be canceled or otherwise influenced simply by applying force to its free-wheeling wheels?? :)
Yup.........pretty simple really but some folks can't seem to fathum it quite yet. Plane at, say, 100 knots forward, treadmill at 100 knots reverse, airplane wheels spinning at 200knots but airplane still moving forward at 100 knots...airplane goes for a ride in the sky

77Woodbridge
12-07-2007, 11:19 AM
OMG...are we really doing this again?!?!?!?!?
Looks like it. :) :sqeyes:

Ziggy
12-07-2007, 11:20 AM
Looks like it. :) :sqeyes:
some thick skulls around...LOL

coolchange
12-07-2007, 11:39 AM
can't beleive how some people will argue a point so strongly that they don't understand. If an airplane is flying at 100mph ags and picks up a 100 mph tail wind will it keep flying?:idea:

Deano
12-07-2007, 11:42 AM
Yup.........pretty simple really but some folks can't seem to fathum it quite yet. Plane at, say, 100 knots forward, treadmill at 100 knots reverse, airplane wheels spinning at 200knots but airplane still moving forward at 100 knots...airplane goes for a ride in the sky
case closed!!!

justfloatn
12-07-2007, 11:47 AM
Will this simplify it enough for those who don't get it:idea: You need to be able to visualize things. Lets say the treadmill is the length of the runway.
The plane is setting on it. Even if the plane was setting still ( tied to something not on the treadmill) and the treadmill was at 100 MPH the wheels would be moving freely spinning at 100MPH. When the thrust is applied with a prop or jet the plane will accelerate forward. The tread mill could spin twice as fast and the only thing that will notice are the wheels on the landing gear.

wright27
12-07-2007, 11:51 AM
No it will not fly, I tried it yesterday.:D

Halvecta
12-07-2007, 12:18 PM
Wheel driven? Where did you get that from?
It doesn't track the speed of the wheels...it tracks the speed of the aircraft itself. The speed of the wheels is irrelevant.
If, according to your line of thinking, the plane is not moving than neither is the treadmill. "The treadmill tracks to speed of the plane" means that the plane and the treadmill must not be moving. If one (the plane) is moving, then the treadmill must not be doing anything to negate the forward movement. If the the treadmill is cancelling out any forward movement, then why would the plane be moving at all? What is causing the treadmill to move if the plane is not moving?
Do you mean the treadmill is moving at a speed that the plane "would" be moving if the treadmill was not spinning.
Either way, the plane has left the building.

Strippoker
12-07-2007, 12:28 PM
so is this going to be on next Wed on Mythbusters big airplane show so you all will finally shut the F up about this????????

LUVNLIFE
12-07-2007, 12:48 PM
so is this going to be on next Wed on Mythbusters big airplane show so you all will finally shut the F up about this????????
Yes it is. I checked their website.:)

Classic Daycruiser
12-07-2007, 01:59 PM
Is this a ***boat site????
Lets start this over again!!!
A ***boat is on a Tread Mill, if it has a sail and wing's, Whats the price of Beef in China:idea: :idea: :idea: :D

Some Kind Of Monster
12-07-2007, 02:06 PM
Now if the plane's liftoff speed was say...100 knots...and the treadmill was fixed at that speed...the plane will take off...but would have to generate twice the thrust it would have to generate if it were on a non moving runway, and the wheels would be spinning twice as fast.
This is flawed ;)

LaveyJet
12-07-2007, 02:27 PM
OK...let's end this once and for all.
The question stated that the treadmill has a speed tracking system on it that tracks the plane's speed, and adjusts its speed to match the plane's speed but in the opposite direction. Basically what this system does is adjusts the treadmill speed so that all forward movement of the plane is cancelled out. No forward movement of the plane = no airflow over the wings = no lift generated = plane will not take off.
Now if the plane's liftoff speed was say...100 knots...and the treadmill was fixed at that speed...the plane will take off...but would have to generate twice the thrust it would have to generate if it were on a non moving runway, and the wheels would be spinning twice as fast.
"Basically what this system does is adjusts the treadmill speed so that all forward movement of the plane is cancelled out"
How did you reach that conclusion? Its just "plane" wrong. The problem says "it adjusts its speed to match the plane's speed but in the opposite direction". Therefore if the plane (fuselage) is not moving, then the treadmill is not moving. If the plane is moving at 10mph then treadmill is moving at 10mph. if the plane slows down, the tread mill slows down. If the plane speeds up the treadmill speeds up.
The only additional drag on the plane is the friction from the wheels. The plane will still have the same aerodynamic drag regardless of the runway motion. If the thrust from the engine is great enough to overcome the additional drag, (I think so) it will take off.
There will be some speed where the aerodynamic drag + the friction of the wheels will = the thrust from the engine. If that speed is great enough, the plane will take off, if not it will continue down the runway. My point is, the plane will be moving forward at some speed, not stationary.

wright27
12-07-2007, 02:39 PM
I tried it again today and the plane took off!!! Now I am really confused.:D

Mandelon
12-07-2007, 03:23 PM
What's that quote?
Better to be silent and thought a fool.......... than speak, and remove all doubt....:D

AZKC
12-07-2007, 04:04 PM
OMG...are we really doing this again?!?!?!?!?
Well it all started in the GulfStream thread, then a Google search, the rest is history:D
And the plane won't fly there is no lift:devil: It aint moving:idea:

coolchange
12-07-2007, 04:29 PM
A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).
Will the plane be able to take off?
Im' amazed at the amount of "information" people add to this basic question. And some of them are pilots!:eek:
everything in this question is irrellevant except that the WING gets airflow and creates lift.

LaveyJet
12-07-2007, 04:54 PM
What is speed? Displacement divided by time.
If there is no displacement, there is no speed and no airflow over the wing.
However, if there is displacement, there is speed and there is airflow over the wing.
If the speed is great enough to cause enough air flow over the wing to create lift, the plane will take off.

maddad
12-07-2007, 05:49 PM
If the conveyor/treadmill were on an incline, do you imagine it can move fast enough uphill to prevent someone from skateboarding down?

Classic Daycruiser
12-07-2007, 07:59 PM
If the conveyor/treadmill were on an incline, do you imagine it can move fast enough uphill to prevent someone from skateboarding down?
Is the skateboard motorized:D :D :D :D

Ziggy
12-07-2007, 08:00 PM
What seems to stump most people is the fact that the wheels are not the driving force behind an airplanes forward thrust so the wheels spin has no relation to the engine speed of the plane whatsoever.
However you want to look at it, the airplane moves forward to activate the treadmill speed and the freewheeling rotation of the wheels absorb the impact of the treadmill.
Have a nice flight :)

DSIDan
12-07-2007, 10:39 PM
What seems to stump most people is the fact that the wheels are not the driving force behind an airplanes forward thrust so the wheels spin has no relation to the engine speed of the plane whatsoever.
However you want to look at it, the airplane moves forward to activate the treadmill speed and the freewheeling rotation of the wheels absorb the impact of the treadmill.
Have a nice flight :)
I understand this concept and agree that if you were able to keep the plane stationary (a teather?) while moving the belt below it, and get the wheel speed to...whatever you like, then regular thrust would equal roughly regular movement and then take off.
The problem is planes cant take off with a teather attached, so sitting on the belt with the wheels not moving and weight sitting atop when the belt turns on the plane moves backwards, thus needing thrust to overcome backwards movement, and get back to just a stop, once making it back to a stop speed the engine will have to continue to provide thrust to keep the plane stationary. It will require additional thrust to move forward for flight. Assuming the plane does not need 100% of its power to take off on a regular runway it is still possible to fly, pending the belt speed and length of time spent moving backwards (enough to get plane to belt speed)

HCS
12-07-2007, 11:27 PM
Does a rocket need wind to fly?

Classic Daycruiser
12-08-2007, 08:29 AM
Does a rocket need wind to fly?
yes...a space ship does not:D :D :D

coolchange
12-08-2007, 08:42 AM
OMG

LaveyJet
12-08-2007, 09:57 AM
plane moves backwards, thus needing thrust to overcome backwards movement
Let me state this again;
The problem says "it adjusts its speed to match the plane's speed but in the opposite direction".
Therefore if the plane (fuselage) is not moving, then the treadmill is not moving. If the plane is moving at 10mph then treadmill is moving at 10mph. if the plane slows down, the tread mill slows down. If the plane speeds up the treadmill speeds up. If the plane stops, then the treadmill stops.
According to the problem as stated, there is no way the plane can move backwards.

CHEETAH24
12-08-2007, 12:15 PM
http://i76.photobucket.com/albums/j40/CHEETAH24/images-1.jpg
who needs a treadmill ??