debated here...

https://www.fiero.nl/forum/A...060811-6-038175.html


Its on myth busters now

dang and me with no tv.

somebody let me know what happens.

quote Originally posted by Jncomutt: Its on myth busters now

Now THAT oughtta settle it!!!

(and I still say I was right!)

It was a show dedicated to plane myths, but I didn't see any treadmill?

[This message has been edited by PontiacJ829 (edited 12-12-2007).]

Flipping frackin crapin shoot I totally forgot about it. Edit: never you mind I'll get to see it on Saturday.

[This message has been edited by The Poopsmith (edited 12-12-2007).]

the plane will fly

EDIT: plain = plane

[This message has been edited by buddycraigg (edited 12-13-2007).]

It will fly.

Reminds me of a question I once asked my sister (answer seems to be obvious to me but she disagreed): if, in a car moving at 100mph, you throw a ball up in the air, and then slam on the brakes while the ball is in the air, will the ball fly forward relative to the car and smack the windshield, or come straight down to the spot from which it was thrown?

Edited for early morning stupidity (see post time).

[This message has been edited by timwdegner (edited 12-13-2007).]

quote Originally posted by timwdegner: If I understand correctly that the plane is motionless relative to the ground, it won't fly.

Oh lord, we're not going over all that again...

Read the damn thread.

quote Originally posted by Jncomutt: debated here... Will the plane fly?

[This message has been edited by Patrick (edited 12-13-2007).]

quote Originally posted by timwdegner: If I understand correctly that the plane is motionless relative to the ground, it won't fly.

Nope. Do you know why? Or perhaps a better question is...why *wouldn't* the plane move?

quote Reminds me of a question I once asked my sister (answer seems to be obvious to me but she disagreed): if, in a car moving at 100mph, you throw a ball up in the air, and then slam on the brakes while the ball is in the air, will the ball fly forward relative to the car and smack the windshield, or come straight down to the spot from which it was thrown?

At 100 mph, wind resistance would play a big part in it. The ball would fly backward because of the relative wind.

quote Originally posted by timwdegner:If I understand correctly that the plane is motionless relative to the ground, it won't fly.

Sorry Tim, apparently you don't understand.

------------------
Ron

It's the Soldier, not the reporter
Who has given us the freedom of the press.
It's the Soldier, not the poet,
Who has given us the freedom of speech.
It's the Soldier, not the politicians
That ensures our right to Life, Liberty and the Pursuit of Happiness.
It's the Soldier who salutes the flag,
Who serves beneath the flag,
And whose coffin is draped by the flag.

[This message has been edited by blackrams (edited 12-13-2007).]

So what was the outcome? I didn't see the show.

Jim

many people seem to think that airplanes are propelled by the wheels. ground speed is irrelevant. you can roll that treadmill in either direction, forward or backward, and at any speed. will make little difference. the jets or propellers push on the air. even if the treadmill was goin backwards very very fast, the airplanes engines will move it up to take off speed, while the landing gear/wheels will be spinning at a unusually high speed - that is all.

airplanes are not powered thru the wheels. ground speed is irrelevant.

quote Originally posted by timwdegner: ... Reminds me of a question I once asked my sister (answer seems to be obvious to me but she disagreed): if, in a car moving at 100mph, you throw a ball up in the air, and then slam on the brakes while the ball is in the air, will the ball fly forward relative to the car and smack the windshield, or come straight down to the spot from which it was thrown?

Of course it will, at least, it will move forward relative to the now stopped car. Even figuring wind resistance, the ball is traveling forward at double digit speeds. The car has stopped within 250 or so feet (depending on the car), probably in about ten seconds. The caveat is, has the ball been thrown high enough? If so, the ball is slowing at a rate slower than the car did, and it will continue up to its apogee, then fall to the ground, still traveling linearly, somewhere in front of the car (probably not on the windshield).

The Plane is never flying if it is connected to the conveyer belt.

Its a lot like saying if a rooster was on top of barn which top faced east and west at exactly noon and laid an egg at that precise moment which side of the barn will the egg fall on?
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Everyone should know the answer--

"roosters don't lay eggs"

[This message has been edited by Butter (edited 12-13-2007).]

quote Originally posted by Butter: The Plane is never flying if it is connected to the conveyer belt.

The plane is not connected to the conveyer belt.

quote Originally posted by AntiKev: The plane is not connected to the conveyer belt.

If its not connected to the conveyer belt then it has to be flying or hangin from something.

Now for something completely different ... Here's a fun (and cheap) experiment that you can all do for yourselves and for the amusement of your friends. You might even be able to win a few bar bets with it:

Get an ordinary helium-filled balloon and tie it in your car so that it is free to move in all directions. Close the car windows and turn the heater fan down to low so that air movement doesn't affect the balloon. Now drive around, accelerating, braking, and turning aggressively. What happens to the balloon? Why? Is it what you expected?

I am wondering, since the Jet's propulsion system has nothing to do with the wheels, would the belt have any effect? Sure some effect, since the wheels must have some drag.

So with the belt running and the engine off, the jet would move backwards. However, as soon as the engines are on I would expect the jet to move forwards again, since the propulsion is a Jet engine and not in any way dependent on the wheels. So I would guess the plane would move forwards and take off.

Unless of course the wheels fall apart from spinning twice as fast as intended.

Inertia rocks!

and, for a full body experience of inertia: smoke a joint - and, now you will see inertia at its grandest - a body in motion stays in motion, a body at rest stays at rest

So, therefore, it will fly off of the treadmill, anyways.

Marvin, the balloon will move to the front of the cabin on acceleration and backward during braking. It will move away from the center of a hard turn. The balloon will seek the highest point in the car which is normally level, except when the car pitches or rolls.

Airplanes fly by the effects of air flowing over the wings. The planes design including the wing, and the weight determine the speed at which it will take off when the air is moving at sufficient speed. If you have a plane that takes off at 50 mph ground speed on a calm day, the same airplane will take off in a 25 mph headwind at a ground related speed of 25 mph. If the wind is blowing 50 mph the plane can lift off setting still. I have a friend that has a STOL Cessna 170 and in a high wind it can actually fly backward and Ive watched him hover it. Now if you take the wind from the rear that will add to the speed required for the wings to provide lift. Same airplane as before with a 50 mph tail wind will have to attain a ground speed of 100 mph to lift off. The AIRspeed indicator on the panel will show the same 50 mph in all the above situations. This is one reason when planes are parked, they need to be tied with rope or chain to in ground anchors. From the front the plane can easily lift without them. There are some other minor factors to figure in, but you get the jist of it.

Oh lol yea sorry guys, I posted when I was half asleep. It'll fly.

As for the ball in the car, the ball is being thrown inside of the car. So the ball will smack the windshield. It's lateral inertia is the same as the car's until the car slams on its brakes. Since at that point the ball is in the air, the car begins moving backward relative to it due to the fact that the ball's inertia is unaffected by the car's brakes.

quote Originally posted by timwdegner: It would seem upon first thought that the balloon would be getting knocked around that car, but for such a light object so easily affected by the gas particles (air) surrounding it, I think it'll remain stationary relative to the car. However, I don't have a helium filled balloon with which to test this out.

I have a minivan and four kids. I have tested it.

I really want to see the episode but am right now curious on how they set it up for the test. Did they use a real piloted aircraft or RC and what was the scale? Also one version of the myth says that the conveyor matches the wheel speed of the aircraft did they manage to be able to do that or did they just get as close as they could?

Well it's not on Youtubes yet but I found this one that seems to cover the same theroy.
http://www.youtube.com/watc...SPAk&feature=related

quote Originally posted by timwdegner: As for the ball in the car, the ball is being thrown inside of the car. So the ball will smack the windshield. It's lateral inertia is the same as the car's until the car slams on its brakes. Since at that point the ball is in the air, the car begins moving backward relative to it due to the fact that the ball's inertia is unaffected by the car's brakes.

OH, inside the car! That's different.

quote It would seem upon first thought that the balloon would be getting knocked around that car, but for such a light object so easily affected by the gas particles (air) surrounding it, I think it'll remain stationary relative to the car. However, I don't have a helium filled balloon with which to test this out.

What about the variable that the one guy posted about the heater being on? Depend on how much heat is generated, the balloon may settle on the seat because of the lesser air density of hotter air.

How many 'Will The Plane Fly' threads are there on the internet I wonder?
They didn't do a test on Mythbusters
From the YouTube video The Poopsmith posted

quote Well, they didn't show it. According to an interview w/ Savage, they tested it w/ an ultralight and a 1/4 mile long conveyor but haven't aired it yet. Well, maybe someday

They did another one of those "internet myths" in the show that aired here last week: If you have a truck full of pigeons sitting on the floor (or anything else) of the truck, and all pigeons suddenly start flying inside the truck, will the truck become lighter?

quote Originally posted by Cliff Pennock: They did another one of those "internet myths" in the show that aired here last week: If you have a truck full of pigeons sitting on the floor (or anything else) of the truck, and all pigeons suddenly start flying inside the truck, will the truck become lighter?

No, it will remain the same weight.

Edit: if the truck is airtight!

[This message has been edited by timwdegner (edited 12-13-2007).]

what if their feet are mounted to the floor?

Okay, I am really confused what this debate is all about:

When one says "will the plane take off" do they mean it will lift straight up into the air, or it will move foward and take off like normal operation?

This whole damn time I am sitting here thinking that if the conveyor belt is moving at the Vr speed, the plane will magically lift into the air. So, my answer was, "of course it won't take off because the plane depends on air speed not ground speed." Then people were saying, "the plane will take off because it depends on air speed and not ground speed" which made me more confused.

So then I saw the video linked with the dad and the kid and how the belt is moving but the plane still propells forward and could then take off if it had more room and I thought, "duh! The plane depends on air speed not ground speed, so the belt could be moving at a billion mph and the plane will still move forward and take off, as long as the engine could overcome the friction of the wheels and bearings"

So, I am more confused about what does "take off" mean?......

quote Originally posted by SonataInFSharp: So, I am more confused about what does "take off" mean?......

"Take off" would mean that the airflow over the wings was sufficient to generate lift.

You can watch it here:

http://video.discovery.com/

You need to download their player, but I watch a lot of shows on there, including "last one standing" which has some pretty awesome episodes.

quote Originally posted by SonataInFSharp: ...so the belt could be moving at a billion mph

Not according to how the scenario was presented to us in this thread - Will the plane fly?

Carefully read over the following (taken from the linked to thread) with special attention paid to what I've highlighted.

quote A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). The question is: Will the plane take off or not?

It's important to understand that the forward progress of the plane is not impeded at all (to any measureable degree). The wheels simply have to turn twice as fast as they normally would (ie. 200mph instead of 100mph).

I originally believed otherwise myself, but I explained the reason for my error Here.

That's the logical hook of the question. All this talk about the conveyor and it's carefully controlled speed makes you think that's important and has to be taken into account. It's simple misdirection. You have to understand that an airplane's thrust, both on the ground and in the air, comes from the engines pushing against the air - not the wheels turning on the ground. As long as the brakes aren't on, the airplane doesn't care what the wheels are doing or how fast the conveyor is moving.

Like this scenario:

You're driving a bus with 5 passengers: Sally, Billy, Tommy, Joe, and Pam.
Sally is 5 feet tall.
Billy is taller than Tommy, but shorter than Joe.
Joe is taller than Tommy.
Pam is 6 inches taller than Joe and 2 inches shorter than Tommy.

Who's driving the bus?

Right, I just watched the episode, and it's not on there.

It even says in the description of the episode that they're covering it!!!

"And if a plane can take off from a conveyor belt speeding in the opposite direction."

quote Originally posted by Formula88: Like this scenario: You're driving a bus with 5 passengers: Sally, Billy, Tommy, Joe, and Pam. Sally is 5 feet tall. Billy is taller than Tommy, but shorter than Joe. Joe is taller than Tommy. Pam is 6 inches taller than Joe and 2 inches shorter than Tommy. Who's driving the bus?

I made a picture.

Crude, but I think it works.

quote Originally posted by leppy_89: I made a picture. Crude, but I think it works.

Excellent teaching tool but, you want know something, some folks will still say it won't fly. For the effort though.

------------------
Ron

It's the Soldier, not the reporter
Who has given us the freedom of the press.
It's the Soldier, not the poet,
Who has given us the freedom of speech.
It's the Soldier, not the politicians
That ensures our right to Life, Liberty and the Pursuit of Happiness.
It's the Soldier who salutes the flag,
Who serves beneath the flag,
And whose coffin is draped by the flag.