For crying out loud, did you even bother to read any of the answers from the guy who posted the question in the first place?

Sorry, you LOSE!!

I guess some people really are just too stupid to educate, kinda sad.

 

The hard part with this question is to get over the whole "Wheels / treadmill" factor. When the prop / jet / turbine starts thrusting the plane will move forward no matter what speed a conveyer system underneath the plan moves at. Think about it, there is nothing stopping the plane from moving forward, if the wheels on the plane didn't turn, or had braking applied then maybe. As the question is posed the plane should move forward and take off.

I found the following thoughts on another site, and they kind of express what us "the treadmill makes no difference" people are saying.

"A thought experiment. Suppose you're on the treadmill at the gym and someone sets the speed to "WHOAH!". You're going to go flying backwards. Now, suppose you have rollerblades on. With just one finger wrapped around the handbar, you'd be able to resist the force of the treadmill no matter what the speed was set to (up until the bearings on the rollerblades started smoking.)

Now, imagine someone gave you a Wile E. Coyote-style Acme rocketpack and lit it off. What direction do you think you'd go?"

 

haha. guess i'm too late to the party, but even after reading the initial post i knew it would never get off the ground.
no lift, no fly.

no matter how much thrust you had, (unless you're a rocket w/ solid fuel boosters like NASA uses) you'd never get off the ground.
but you also need thrust too.
now, theoretically if you had a wind tunnel large enough, and powerful enough to generate fullscale winds, you could possibly get the plane to fly, but you would also be lacking thrust so it would have to be in a gliding state which would depend on the plane design.
if it were shaped more like a glider, then yes, it could stay in flight, but if it were say a jumbo jet, it would prolly not lat too long (i.e. see jumbo jet at altitude loose engine power, it will eventually fall from the sky)

 

Christ, I cannot belive how ignorant some people can be, can't you freaking read?

 

You are caught up in too much extra math man. Keep it simple, keep it Newtonian.

For every action there is an equal and opposite reaction. Therefore the engine will thrust the plane forward generating lift on the wings.

But wait! you say, "There is a tread mill beneath the plane moving in the opposite direction"

It doesn't matter... The wheels are not the force driving the plane forward (you all are thinking cars here) they are simply spinning there at whatever speed they have to spin to try and keep up with a plane that WILL MOVE in the other direction because of basic physics.

The sad part, a lot of people with college degrees aren't getting this...

 

OK read the 1st post. If the runway matches the speed of the plane which the first post says it does, then there would be no lift. First off, when a jet takes off, yes it is not powering the wheels, but until it takes off, the wheels spin due to the forward momentum the thrust creates. If the ground under the wheels moves exactly the opposite direction of the speed of the plane created by the thrust of the engines, then the plane will remain stationary. Since the plane is stationary, no lift is created on the wing which means NO FLIGHT! You can add any unknowns to the equation, but read the first post.

Remember the first post states that the conveyor matches the planes speed, not the wheels (not that it would matter).

If you think I am wrong, then remove the wheels from the equation. The plane is sitting on its belly on the conveyor belt. Will it fly?

 

that's what i get for not reading the whole thread

 

It would only make sense to use a common inertial reference point for measuring the velocity of both the vehicle and the belt (a fixed point on the earth, like a tree).

In that case, whatever the absolute forward velocity of the car (not what the speedo reads, but the actual distance that the car is traversing versus time relative to the tree), the treadmill would be moved backwards at the same rate.

If you floored the car in this scenario, it would most certainly accelerate and reach the end of the treadmill. At any instant, the car would have some velocity +V, the treadmill surface would have some velocity -V, the car's speedo would read 2V, and the wheels would of course be spinning at a speed equivalent to the car driving at 2V on stationary ground (assuming no slippage).

Now if you for some reason use two different reference frames for measuring velocity (I don't see why you would ever assume that), such as measuring the car's speed relative to the treadmill surface, and then the treadmill surface relative to fixed ground, then yes the car will stand still relative to the fixed ground.

However in the case of the plane, I argue that it doesn't matter what reference frame you use for measuring plane velocity when matching the treadmill velocity, it will still take off with ease.

 

Again, bad math. Essentially what you are saying is that a wing has to move forward for there to be lift when in fact the air can move over the wing while it remains stationary thus generating lift. Strap a glider to a pole and generate a 150 MPH wind and I promise the glider will rise.

Then there is the whole matter of it NOT MATTERING because the plane would indeed be moving forward.

Thank you drive through.

 

No arguement with your statement if a head wind was in the equation. Where in the original post does it state that there is a head wind? Do you really think the turbine on a jet can gernerate enough flow over the wing for lift if the plane is stationary? Not a chance. The only way the plane is moving forward would be if the runway was not matching the plane's speed. Since it is matching the plane's speed, the plane is stationary. Unless you can show me how the plane is moving as stated in the original post, then there is no physical way to generate lift on the wing without airflow. If the equation stated that there was in fact a 180 mph head wind, well then the plane would lift depending on the plane's weight.

By the way, if the glider is in fact strapped to the pole, how high is it going to lift?


Back of the short bus please.

 

oh christ.. let it die

 

Sorry Scott, I be done!

 

Like I said, it doesn't matter. This is a physics question which assumes things like "frictionless wheels" and a conveyer belt that can magically match the wheel speed of an airplane. My point was your statement was incorrect about the wing needing to move forward to create lift was false, and it still is.

For those of you who would like to read more about this subject, it is truly a fun read for the nerd in all of us. May I suggest the following links?

Someone actually did a mini test of this question.

http://www.avweb.com/news/columns/191034-1.html

And after 270 pages, the "it will fly camp" beat down the non believers. Most people are eventually convinced that the wheels don't matter as there is nothing in their spinning (at any speed) to stop a plane from moving forward.

http://forum.physorg.com/index.php?showtopic=2417&st=0

Rock on!

 

ok I am done too.

 

I'm done too!