Mythbusters tackles the plane/treadmill

[Pitbozz]

I disagree... a treadmill and model airplane will prove the concept. As long as the take off speed of the plane is less than the belt speed of the Treadmill, then the treadmill has the advantage since it can over compensate.

It's basically a Cause and effect thing...

The airplane starts to move forward, causing the belt to rotate equally in the opposite direction, but the belt can ONLY effect the tires that contact it. Since the tires have NO control over the speed of the plane, other than to lessen rolling friction, the plane will take off as it would any other day.

Simply because the belt only touches the tires, and the tires only spin... nothing else.

The only purpose of the "speed matching" part of the question, it to trick people into thinking it has importance. When it is not important, that belt could be rotating 1000mph in reverse, and the only thing that will be effected is the rotation of the tires. Which can't keep the plane still.


If TU24 doesn't kill us all on the 29th , Mythbusters will put this to bed on the 30th.

:smile: :smile: :smile:

 

[MENTL231]

This thread will self destruct in 5 day's..




AND the friggen plane wiiiiiiiillllllllll tttttaaaaaakkkkkeeeee ooooooofffffffffff.

Where are the Wright brother's when you need them.. They would have a field day with the people who didn't think it will take off.. Partially because most of the "wrong people" (if you will) are waaaay over analizing the question and not the concept. It's partially a trick question. Truth be told. In the question it brings up phrase's like matching speed. In which simple mind's get caught on the hook and other's move on to the obvious.

Like it was said before, most small plane's won't see 1000 mph. And if there were a treadmill that would rotate the landing gear that fast. A plane's thrust will still overcome it and take off. And at that time, you can worry, but only if you are in the plane or own it, if the wheel bearing's can take that abuse.


Check mate!! And I don't have to watch Mythbuster's. :tongue:

 

[bobc455]

See nobody understands what makes a plane move.

Actually the wheel assemblies contain powerful V8 engines. These push the plane forward, and the momentum pushes it up in the air so it can coast all the way to its destination. The jets are just there for the cool noise.

If a conveyor belt moves backwards, these V8 engines would over-rev before takeoff and the plane would burst into flames.

I've voting "tuesday".

 

[87GNSteve]

I understand what you guys are saying.
I agree now the plane will take off.
Sorry for being so dense.
:redface:

 

[jpratt]

I understand what you guys are saying.
I agree now the plane will take off.
Sorry for being so dense.
:redface:

Welcome to the enlightened side

 

[Pitbozz]

I understand what you guys are saying.
I agree now the plane will take off.
Sorry for being so dense.
:redface:

You have taken the red pill. (Matrix reference for those who missed it!)

Welcome to the truth.

 

[darkred87T]

If it does, I'll buy a parachute as an additional safety device the next time I run on a dyno. I'll also install a rear wing for the additional downforce on the rollers.

And please post the video of your car on a dyno with a big wing and parachute.

 

[83hurstguy]

If the plane doesn't remain stationary, then what is the point of the experiment?

the point of the question is to trick people into thinking that the plane stays stationary. Question never says that, but people assume that.

 

[at7we2]

guys....this is not high level physics. this really is pretty basic principles. I'm surprised it's supposed to be on Mythbusters.

the whole airplane on the treadmill "scenario" *can* be duplicated easily by anyone with a common exercise treadmill and two people.

1. get on the treadmill and start walking, jogging, running, whatever. Your pace does not matter as long as you and the treadmill are matched (as in the theoretical scenario with the plane)

2. have someone apply a forward force (PUSH) you from behind. the forward force of someone pushing you represents the thrust from the plane's engines.

So...what happens??? You move forward *regardless* of what speed your feet (plane's wheels) and the treadmill are moving at.

The reason you will move forward is the exact same reason the plane will develop forward velocity (and take off). The person who pushed you while you were on the tread mill applied a force to you that had an opposite reaction down to the ground under their feet. The ground (Earth) has more mass than you so you move in the direction of the force they applied. This is exactly what will happen when the planes engines produce thrust. The only difference is, the engines are pushing against the air around the plane instead of the ground/Earth.

Does this bring anyone *else* over to the "yes" side?

 

[turbofabricator]

Place a 747 on a frozen pond, ( a real BIG frozen pond) and then lock the brakes. (incidentally, they are NOT on front wheels) and then go full throttle. Will the plane just sit there? Or will it take off? Same scenario, just opposite.

 

[at7we2]

Place a 747 on a frozen pond, ( a real BIG frozen pond) and then lock the brakes. (incidentally, they are NOT on front wheels) and then go full throttle. Will the plane just sit there? Or will it take off? Same scenario, just opposite.

Another excellent comparison. I like it!!!

 

[TurboDave]

I'm absolutely flabbergasted by the huge number of "no" votes!!

It's obvious that our public education system is still living up to it's "government sponsored schools" lofty goals.

 

[GullsGN]

But the thing is, the speed of the treadmill doesn't really matter. The plane will roll out and take off no matter what the speed is.

Because......













wait for it.......












almost.........












The treadmill is irrelevant.
The treadmill is irrelevant.
The treadmill is irrelevant.
The treadmill is irrelevant.
The treadmill is irrelevant.

Yup, I completely agree. It will fly, no matter what the speed of the treadmill. I was answering the question that someone asked, "is it matching the planes speed or the tires speed?" The treadmill is irrelevant, or to put it another way, the treadmill don't matter a hoot!

 

[GullsGN]

Pablo,

You seem like a pretty fart smeller. You are correct, but you asked for an instrument that would tell you what the ground is doing. In the most simplest of terms, it can tell you how fast it is approaching the aircraft or vice versa. I also understand how it works through pressure.

If I am flying an aircraft, and I run out of gas or the engine stalls and I lose forward motion and I roll into a dive. Now would that altimeter tell me anything?

I know it has nothing to do with ground speed, but you asked for an instrument that would tell you something about what the ground was doing. Now repeat after me. An altimeter can tell you how long you have to kiss your a$$ goodbye :biggrin: in that scenario.

You are correct also that airplanes use air for travel. Where will that air come from if forward motion is negated?

In this scenario the altimeter will not tell you how long you have before you go splat, UNLESS, you know the ground elevation below you. Say the airport you take off from is at 1000ft. This is what you set your altimeter at before you take off. Then you fly over the Rockies. When you are flying over at 200ft your altimeter will not tell you you are 200 feet from the peak. It will tell you you are at 10,000ft or whatever 200ft plus the hight of the mountain is. So if you go into a nose dive, unless you know the hight of the mountain and quickly subtract that from your altimeter reading you would know that you have 200 ft, but only if you know the exact hight. And it won't tell you how long just at what altitude you will go splat. If you are falling through clouds you will know nothing cuz you don't know the altitude above sea level that the ground underneath you is. Whew.

 

[Pitbozz]

guys....this is not high level physics. this really is pretty basic principles. I'm surprised it's supposed to be on Mythbusters.

the whole airplane on the treadmill "scenario" *can* be duplicated easily by anyone with a common exercise treadmill and two people.

1. get on the treadmill and start walking, jogging, running, whatever. Your pace does not matter as long as you and the treadmill are matched (as in the theoretical scenario with the plane)

2. have someone apply a forward force (PUSH) you from behind. the forward force of someone pushing you represents the thrust from the plane's engines.

So...what happens??? You move forward *regardless* of what speed your feet (plane's wheels) and the treadmill are moving at.

The reason you will move forward is the exact same reason the plane will develop forward velocity (and take off). The person who pushed you while you were on the tread mill applied a force to you that had an opposite reaction down to the ground under their feet. The ground (Earth) has more mass than you so you move in the direction of the force they applied. This is exactly what will happen when the planes engines produce thrust. The only difference is, the engines are pushing against the air around the plane instead of the ground/Earth.

Does this bring anyone *else* over to the "yes" side?

Seeing as how I said this exact thing (although, not as wordy as you! ) in post 25 and we are now at post 230'ish, I will say it won't.

 

[Pitbozz]

Place a 747 on a frozen pond, ( a real BIG frozen pond) and then lock the brakes. (incidentally, they are NOT on front wheels) and then go full throttle. Will the plane just sit there? Or will it take off? Same scenario, just opposite.

DUUUUUHH....this one is easy. If it is on ice, the tires are just going to spin!

 

[Geoff87]

Okay. Okay. I FINALLY get it! It's a trick question. All along I was assuming that the plane would remain still. Geez it took me long enough!

Boy do I feel dumb.... (not the first time, surely wont be the last...) Thanks to all who tried to explain this! Is it too late to change my vote?

BTW, I have a digital video camera. Anyone have a parachute for sale?

 

[at7we2]

I'm absolutely flabbergasted by the huge number of "no" votes!!

It's obvious that our public education system is still living up to it's "government sponsored schools" lofty goals.

[SMACK!!!] OUCH!! :biggrin: :biggrin: :biggrin:

 

[Pitbozz]

Okay. Okay. I FINALLY get it! It's a trick question. All along I was assuming that the plane would remain still. Geez it took me long enough!

Boy do I feel dumb.... (not the first time, surely wont be the last...) Thanks to all who tried to explain this! Is it too late to change my vote?

BTW, I have a digital video camera. Anyone have a parachute for sale?

You are partly correct. You get it now. Welcome.

But it isn't really a trick question. People who had it wrong from the beginning and then FINALLY see the light always say it is a trick question or they didn't understand the wording.

Now let me know how that wing on your next dyno run works out for ya'.

 

[lyonsd]

56 yes to 43 no!!!

That's pretty sad.