Philosophical topics/speeches

[EricG1793]

Well, the ONLY thing I like my Science teacher about is if I didn't have her, I probably wouldn't have understood a word of your post.

Well, the way an airplane moves is Newton's Third Law. When the hot air comes out of the back of an airplane, the air pushes back on the hot air coming out, thus making the airplane be pushed forward. The conveyor belt would probably have nothing to do with whether the plane took off or not. If it was REALLY moving fast, it probably would impede the plane's progressing forward, but I doubt that a belt that big can move that fast.

[wolf_wizard]

True, but you have to consider the possibility of the conveyor belt moving that fast. So, for your question, could you give me more exact information? like how many Ns of force the conveyor belt is moving with, how many Ns of force the airplane is moving forward with, and how many Ns of force an airplane needs to take off at? or you could just give me the acceleration... or is it kind of the same thing? oh well, I think I would need that info. anyway...

[kk]

Yay! A mythbusters question! I have heard about that myth, but I haven't watched the online video (stupid dial-up internet connection!), and I also haven't watched the "Airplane Hour" episode (yet).

I think the plane would take off. But that would depend on the speed/power of it, and that of the treadmill...

[vashmata]

Well, first, without checking how a plane works, I would say no, because I at least think that the wheels are what power it on the ground, and then in the air, the engine takes over. In that case, the plane wouldn't be able to get enough momentum to get into the air, because of the ground constantly pulling it backwards.

Then I looked on the internet. I found this answer. It's most likely right, and I partially agree with it(in white):
<span class="ev_code_WHITE">The only effect of the moving runway is to make the wheels need to spin twice as fast. But the wheels don't make the plane go, it's the thrust of the engines that counts. The plane may experience a little extra drag due to friction in the wheel bearings, but once it develops a little lift that goes away.</span>

I think that the runway(treadmill) would have to be very long, and more power would have to be put into the thrust, if it were to take off.

For those of you who want it, this is the link: http://answers.yahoo.com/question/in...5213700AAaWyTK

[wolf_wizard]

Well, technically, wouldn't the wheels be moved by the engine, evven when on the ground, as the wheel wouldn't otherwise be acted upon by an unbalanced force, and the plane wouldn't be able to get going fast enough to lift off. So, I think that it would still all depend. and, i was assuming that the runway would be very long, though that is a decent factor to add in. So, the plane would need more thrust, as you said. even if it was a regular airplane, I think I would still have to know how fast the runway was going in the opposite direction, and, if it was still possible, who would pilot it, and their skill, as it still might be possible to lift off and then not possible, depending. So, there are some more variables that I think you need to clear up (if you can) Eric.

I know, i'm picky.

Dai all

[EricG1793]

I don't know... I'll show you the thread where the idea originally came around on the Mythbusters fansite:

Never mind. There are several talking about that.

Here are search results for "Air plane": http://community.discovery.com/eve/f...ords=Air+plane

Read more about variables and whatever there.

EDIT: Gaah! You have to be logged in for that!

Hmm...

Well, I'll give a few threads about the airplane/treadmill thing:

http://community.discovery.com/eve/forums/a/tpc/f/95519...451940329#4451940329

Never mind, one of them. Because I've run out of time, but just go to Discovery.com/Mythbusters and look for the forums.

I can post more links to more airplane/treadmill threads later.

[Dragon Writer]

I believe that it will not work for one reason: The plane moves slowly at first. The treadmill does not change speed. either it moves to slowly at first, in which case it falls off, or it moves to fast in the end, in which case it falls off. Either way, i'm fairly certain it's not good-particularly if it ends up with half on, half off. At the very least, it ruins the treadmills, and it can't be good for the wheels! It has to be a big fall, because it has to be a GIANT treadmill to hold up the wheels. To so much as get it on, it would have to be at a slant most likely-which might take care of the problem, but might just result in a greater fall, and hitting the tail, flipping the plane on the way down.
:P

[mysss]

hmm...

Well, the plane would take off, until the speed of the conveyor reached the threshold at which its speed was equal to the amount of extra speed that the plane's engines can produce at takeoff beyond what they need to produce for the plane to take off successfully.

Once the conveyor moved faster than that threshold, the plane would not be able to take off, barring wind conditions which would change the force required from the engines.

The plane's acceleration needs to be taken into account if the conveyor is of finite length. In this case, I think that a plane that could accelerate to a speed faster than that of the treadmill before it was pushed off the back would simply fly once it reached the front end. In the case of a fixed-length treadmill the plane's speed would just have to overcome the treadmill's speed to go off the correct end. Um, unless the fall from the treadmill to the ground wasn't long enough for the plane to fly before it crashed somehow.

Is this plane defined to be a jet plane? I don't think it matters, but everyone's making that assumption. And I think this was meant to be discussed using an infinite runway...but maybe not. We basically need to define the variables in the experiment: the plane's acceleration, wind conditions and their effect on the experiment, the plane's speed needed to produce enough lift for takeoff, the treadmill's speed, the treadmil's length, and what happens if the plane falls off the treadmill at each end.


O.o Should I feel kinds dumb for expending this much energy on this??

[EricG1793]

I'll pop back here briefly just to help everyone by saying that I researched and found out that the date this will be airing is January 30th. This year. I went to the air schedule for Mythbusters and set up an Email reminder, so I WON'T!... miss it.

So. We have... a bit less than nine days to predict.

I still insist that it'll take off.

Editing a message to try and get my new avatar to appear... I've never, ever used an avatar, so let's see how it goes!!

[alla]

http://visearth.ucsd.edu/VisE_Int/aralsea/bigone.html]this imageRichter Scale

[EricG1793]

To Alla, and anyone else who said that the plane would take off....

WE WERE CORRECT!!

First they did the plane on an actual exercise treadmill (Jamie's). The remote-controlled plane did go forward, but it lost course. Then, they got a long (25 feet?) piece of paper, put the airplane on the paper, and then moved the paper in the opposite direction the plane was trying to take off in at the speed that the plane takes off at. It didn't work at first - they doubled the paper, putting it side-by-side. Then... LIFT OFF!!

Then they did the same thing with a stunt pilot and a 400-pound airplane, the 1000-foot long piece of... canvas, I suppose it was, being pulled by Jamie's truck at 25 MPH. The pilot said before they did the experiment, "I'll probably just sit here like a brick." He was wrong, though; after the test, he said he couldn't feel a difference between taking off from still ground and taking off from a conveyor belt.

The only dissatisfaction I had with the way they did all this is that it would have been great to test with the conveyor belt going at different speeds: one speed slower than what the plane moves at to take off, one the same, and one faster. They only did it the same. But, it DID take off, so it answered my question.