Will the plane fly?

[smokinwrench]

This has been argued forever. If a plane is on a free folling conveyer belt will it take off?

We will get our answer Wednesday 9pm E. Myth Busters are going to tackle this myth.

[ATC-Eric]

I say no, but am excited about the experiment.


Sorry to hear about you foot homeboy. It sucks to be doing something so mundane and simple when you break it. A cool story would have made things a little better :lol:

[TwoHundredEx]

http://img260.imageshack.us/img260/2281/planeuw2.gif

:D

[Billy Golightly]

I think the original question is something to the effect of, a plane is setting on a conveyor belt, as the plane speeds up so does the conveyor belt matching its speed in the opposite direction, can it take off?


So I ask myself, self, if I have an air boat in the middle of the river, does it take more throttle to go upstream, then down stream? and the answer is yes, it does. Now what happened if the stream was powerful enough that it was constantly increasing in speed as I tried to go up it? I think I'd have a hard time going anywhere.

[RedRider_AK]

I like TwoHundredEx's take on this matter. :lol:

[Dammit!]

The plane takes off!!! :lol:

[SYKO]

my answer is scientific and fact oreinted....








































I dont give a damn......




:welcome:

[SWIGIN]

you need air movement over the wings for lift...... if the engines are just keeping it on the tread mill, its sitting still and the wings get no lift

[69HemiGTX]

Actually, the scenario depicted by TwoHundredEX is both correct and incorrect at the same time. The only way the conveyor will move in the opposite direction is if the wheels produce a rotational moment. This is assuming the conveyor is unpowered. Newton's Third Law of Motion: For every action, there is an equal and opposite reaction. The only appreciable force is applied to the airframe of the plane, which causes the plane to move forward. If the wheels provided a rotational moment, the belt would react by moving in the opposite direction. The wheels of an airplane are not driven by any force, therefore, they cannot deliver any rotational force to the surface below them. Rolling resistance is the only force seen between the wheel and ground. This rolling resistance, in a perfect scenario, would actually cause the belt to move in the same direction as the airplane, but at a slower rate due to the difference in friction between the belt and the conveyor and the airplane and the air. Confused yet?

Do this experiment if you can. Find a conveyor with rollers instead of a rubber belt. The rollers make it much easier to do this because you won't be able to produce enough force manually to overcome the friction of a rubber belt. Take a bicycle and roll it across the conveyor, increasing speed with distance traveled, without using the pedals. This simulates the force the engines inflict on the plane and its resultant acceleration. Remember, no force goes to the wheels. Guess what? The rollers will roll in the same direction as the bike, but at a slower rate. Amazing, huh?

Now what Billy is talking about actually would happen. If an airplane is on a conveyor belt that can accelerate fast enough to keep the airplane relatively still, the airplane will not take off, no matter how much throttle is applied. The thing to remember here is that the belt is powered by an outside source and is not driven by the airplane. Airplanes only take off when the relative wind across their wings is enough to produce a resultant lift greater than the weight of the airplane. If the airplane doesn't move fast enough relative to the air it is passing through, the wings will never produce the force necessary for flight. The wheels might be spinning at 100 knots, but if the wings are only moving 5 knots and the minimum takeoff speed (V1) is 75, the plane will not leave the ground.

Now are you confused? :wondering :lol: :beer

[TwoHundredEx]

Now are you confused? :wondering :lol: :beer

More than you can imagine.....
:lol:

[69HemiGTX]

More than you can imagine.....
:lol:

Mission accomplished. :p

[SPD FRK]

Now are you confused?


Not even a little. Although BG's explanation was easier to comprehend.
Plane ain't goin' nowhere until either it moves fast enough through the air or the air moves fast enough past the plane.
Are there really people who need this proved to them? Pity.

[The Goat]

am I the only one who sees the problem when they try to turn the belt off...or cut power to the engines? the plane is gonna go one way or the other, cause enither wil be able to be turned off at the exact instant.

I can see the headlines now.

[Brockey]

I cant see it flying. I figures the plane will just slowly drive off the conveyor. The wheels dont turn, the engine propels the plane and air flow under the belly and wings make it lift. So in my mind it isnt going anywhere. Now if that could generate enough airflow to point under the plane would it fly?, answer still is no. It would lift and not go forward. It needs the thrust forward with airflow under the plane. Nevertheless I will watch mythbusters as I love the show. Just my .02 cents.

[Yamada]

The plane take off!

[Billy Golightly]

Actually, the scenario depicted by TwoHundredEX is both correct and incorrect at the same time. The only way the conveyor will move in the opposite direction is if the wheels produce a rotational moment. This is assuming the conveyor is unpowered. Newton's Third Law of Motion: For every action, there is an equal and opposite reaction. The only appreciable force is applied to the airframe of the plane, which causes the plane to move forward. If the wheels provided a rotational moment, the belt would react by moving in the opposite direction. The wheels of an airplane are not driven by any force, therefore, they cannot deliver any rotational force to the surface below them. Rolling resistance is the only force seen between the wheel and ground. This rolling resistance, in a perfect scenario, would actually cause the belt to move in the same direction as the airplane, but at a slower rate due to the difference in friction between the belt and the conveyor and the airplane and the air. Confused yet?

Do this experiment if you can. Find a conveyor with rollers instead of a rubber belt. The rollers make it much easier to do this because you won't be able to produce enough force manually to overcome the friction of a rubber belt. Take a bicycle and roll it across the conveyor, increasing speed with distance traveled, without using the pedals. This simulates the force the engines inflict on the plane and its resultant acceleration. Remember, no force goes to the wheels. Guess what? The rollers will roll in the same direction as the bike, but at a slower rate. Amazing, huh?

Now what Billy is talking about actually would happen. If an airplane is on a conveyor belt that can accelerate fast enough to keep the airplane relatively still, the airplane will not take off, no matter how much throttle is applied. The thing to remember here is that the belt is powered by an outside source and is not driven by the airplane. Airplanes only take off when the relative wind across their wings is enough to produce a resultant lift greater than the weight of the airplane. If the airplane doesn't move fast enough relative to the air it is passing through, the wings will never produce the force necessary for flight. The wheels might be spinning at 100 knots, but if the wings are only moving 5 knots and the minimum takeoff speed (V1) is 75, the plane will not leave the ground.

Now are you confused? :wondering :lol: :beer



Whoa, I didn't think anyone would agree with me! Haha. I wish I could remember the exact wording of the question, I think that has a lot to do with whether it can or not. It seems like it was worded sort of tricky, like it made you think one thing but was actually talking about another. Maybe I can remember to check out this episode of mythbusters coming up...

Oh yeah, I forgot about this: http://www.3wheelerworldforums.com/showthread.php?t=44770

[Jason Hall]

Wow I fell for this once. Yes the plane will fly. The thrust from the engine pushes the plane forward. The wheeles have nothing to do with the forward motion of the plane. It really plays games with your mind, but It WILL fly. The only reason a plane needs wheels Is so It will have something to roll on, otherwise It would shoot sparks off the belly. It also needs the wheels to help It STOP, once It lands back on the ground.

[Dammit!]

There is now way for any conveyor belt to keep the plain relatively still. Plane engines (be them props or jets) push against the air. What the wheels are doing has no effect. None. Zero. Nadda. Especially when you look at the wording of the original riddle. I'll have to paraphrase since I don't remember it exactly but it asks "if the conveyor belt moves in the opposite direction of the plane" which insinuates the plane IS moving forward and that the conveyor belt matches this forward speed in the opposite direction. So if the plane is moving 250mph, the belt is going 500mph. This would have no effect on the plane reaching take off speed. Some people want to take it further than the original question goes and crank up the treadmill to be equal to the force of the engines. The question never says anything about doing that and even then the plane would still move forward because the engines push against the air and not the ground.

Now, I think where people get confused here is they think the plane will be sitting still with it's engines cranked and no air running across the wings to create lift. Like if the plane were chained to a stationary object and unable to move. In that case it wouldn't take off. The thrust of the engines pushes against the air and makes the plane move forward (nothing to do with the wheels spinning), the air running across the wings as a result of it's forward movement is what makes it take off.

[Jason Hall]

Here Is another way to look at It. How does a plane with pontoons lift off. It has thrust from the engines/prop moving the plane forward. It very easily over powers the drag of the pontoons In the water and creates lift and fly's away.

[Dammit!]

God I can't wait until Wednesday. :lol:

[Jason Hall]

Me neither Dammit. This will be funny :lol:

[The Goat]

it really all depends on how you look at it.

if the belt is doing 500...and the wheels are freespinning, the plane can take off.

if the belt is doing 500...but the wheels are not spinning, and the plane is doing 500 mph in reverse, the plane likely won't be able to take off.

if the belt is freerolling...the plane takes off.

if the belt doesn't move at all...the plant takes off.

if the second option is tried...it's likely a few people will die.

[Red Rider]

Actually, the scenario depicted by TwoHundredEX is both correct and incorrect at the same time. The only way the conveyor will move in the opposite direction is if the wheels produce a rotational moment. This is assuming the conveyor is unpowered. Newton's Third Law of Motion: For every action, there is an equal and opposite reaction. The only appreciable force is applied to the airframe of the plane, which causes the plane to move forward. If the wheels provided a rotational moment, the belt would react by moving in the opposite direction. The wheels of an airplane are not driven by any force, therefore, they cannot deliver any rotational force to the surface below them. Rolling resistance is the only force seen between the wheel and ground. This rolling resistance, in a perfect scenario, would actually cause the belt to move in the same direction as the airplane, but at a slower rate due to the difference in friction between the belt and the conveyor and the airplane and the air. Confused yet?

Do this experiment if you can. Find a conveyor with rollers instead of a rubber belt. The rollers make it much easier to do this because you won't be able to produce enough force manually to overcome the friction of a rubber belt. Take a bicycle and roll it across the conveyor, increasing speed with distance traveled, without using the pedals. This simulates the force the engines inflict on the plane and its resultant acceleration. Remember, no force goes to the wheels. Guess what? The rollers will roll in the same direction as the bike, but at a slower rate. Amazing, huh?

Now what Billy is talking about actually would happen. If an airplane is on a conveyor belt that can accelerate fast enough to keep the airplane relatively still, the airplane will not take off, no matter how much throttle is applied. The thing to remember here is that the belt is powered by an outside source and is not driven by the airplane. Airplanes only take off when the relative wind across their wings is enough to produce a resultant lift greater than the weight of the airplane. If the airplane doesn't move fast enough relative to the air it is passing through, the wings will never produce the force necessary for flight. The wheels might be spinning at 100 knots, but if the wings are only moving 5 knots and the minimum takeoff speed (V1) is 75, the plane will not leave the ground.
Without hearing the original scenario put forth by the Mythbusters, I don't know if it will fly or not, but everything that 69Hemi said above is correct. On takeoff, the wheels of an airplane only need to provide friction to keep it going straight down the runway until it has enough airflow that the control surfaces become effective.

[Jim mac]

you need air speed over and under the wings to get the plane to lift. the conveyer belt can be spinning 2000mph but the air above the belt is not moving. so you put a plane on the conveyor, power up the conveyor and plane, if the conveyor is going 200mph and the plane, jet or prop, powers up for the plane to move so its sitting stationary. there is no airflow over the wings. so no lift, no fly. If you hooked a speedometer to the wheels it would be showing you 200mph ground speed. but air speed will read 0. There is a guage that sticks out of the front of the plane, basically a tube that reads how fast the plane is moving through the air. Now if you get the plane to power up to 400mph ground speed. that would be 200mph air speed. then you would have a plane capable of flying. I work with a guy thats got a pilots liscense and tried to get a simplified explanation. jim

[Jason Hall]

The wheels could be spinning 9000 mph and the plane will still have lift because the thrust pushing air Is moving the plane, not the wheels. The wheels are like an Idler pully on the belt that turns your accesories on the front of you engine In your car. If you unhook the belt, the Idler just spinns, It has no drive at all. The only time the wheels of the plane do anything besides roll Is when the brakes are on. There Is no driveshaft that Is connected to the plane at all. How do the tires propell a plane when It Is In flight. They don't, the THRUST from the engines propell the plane with AIR. If you guys were right, then you would be able to stop a plane from going forward by holding a rope tied to the plane. Do you think you could over power the thrust of a plane with a rope tied to It?

[Billy Golightly]

If the ropes tensile strength increased at the same rate of the thrust.....

[Jason Hall]

Ok I'll try this one more time. Do we all agree that air/ thrust moves a plane? If air/thrust moves a plane then why would the ground have anything to do with forward motion? Forward motion will happen no matter what the conveyor Is doing under the plane, because the thrust from the engines Is pushing the plane. The wings will create lift. The plane will not just lift straight up, It will cover the same distance with or without the conveyor until the forward motion of the plane (because of Air/thrust) creates enough lift for the plane to lift off.

If the plane was tied to the ground with a cable behind the conveyor, It would not lift off. If the plane Is moving forward because of thrust then It all the sudden reached the end of the conveyor, the tires would Instantly change speed, but the plane would still move forward because the wheels have no drive to connect them to the plane just free wheeling bearings. What I just explained works the oposite way when a plane lands. The wheels are stopped, when they touch down on the ground they Instantly start to spinn the same speed the plane Is moving through the air. If there was drive or alot of resistance between the wheels and the plane, as soon as the plane touched down It would Instantly nose dive and crash.

[Billy Golightly]

The riddle says the planes speed and the conveyor are linked, not the wheels. So yes, I do agree, wheel speed is irrelevant. :D

[Jim mac]

dont forget its the "airspeed" over the wings that give it lift. so if the conveyor is going 200mph and the plane if sitting there it would be traveling backwards 200mph. Say you have a cessna 172 that needs 75mph to take off. turn it so the conveyor is going to get the plane moving forward, then at 75 mph the plane will start to lift. even without the engine running. But turn it around, and the plane is going backwards 75mph, turn on the motor. spin it up so you get 0 air speed and the motor is spinning away and the plane is going nowhere, no air over the wings. so its just sitting there. its like taking the same cessna and taking it off into a 20mph headwind. the actual ground speed is only 55mph when it lifts off, but the windspeed is 75mph so it flys. But if the wind stalls just after takeoff, and you dont have a true 75mph the plane comes down. My freind at work knows of a guy that did just that, unfortunately he and the plane didnt make it. Jim

[smokinwrench]

You guys just cast your VOTE that way we will know who was wrong and who was right.

[OldSchoolin86]

LMAO, the votes are tied! I love this one, it's amazing how hard it is for people to deal with the idea that the wheels on the plane... that touch the conveyor..... have nothing to do with how a plane takes off........................ the plane will take off just about the same as any other day. It will travel down the runway, build speed, take off and have wheels that are spinning twice as fast as normal.

[Dammit!]

The riddle says the planes speed and the conveyor are linked, not the wheels. :D

Which means the plane IS moving. If the plane is moving 180mph one way and the treadmill is moving 180mph the other way, you have 360mph wheel speed but still the normal 180mph wind speed the plane needs to fly.

It wouldn't matter if the treadmill was moving 10,000mph. The plane is still going to move forward and take off because it isn't driven by the wheels.

I saw a sneak peak of the mythbusters show and I'm afraid now that they aren't even doing it right. Looks like they put a plane on a conveyor belt, started up the belt and had the plane just match the speed of the belt. In that case OF COURSE it's not going to take off. That's retarded. The plane has to be moving through the air to take off and in the orginal question it says the belt matches the plane's speed, not the other way around. I'll be extremely disappointed in them if they do it that way.

[Dammit!]

http://www.youtube.com/watch?v=4owlyCOzDiE&feature=related

[OldSchoolin86]

I'll be extremely disappointed in them if they do it that way.Wouldn't be the first time they screwed up something.

[Dammit!]

Wouldn't be the first time they screwed up something.

Very true. They're gonna get roasted if they screw this one up though.

Here's the original question with the original wording for those that have not seen it.


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). Can the plane take off?"

The answer is in the question. The plane is moving forward. The rolling resistance of the wheels isn't going to do **** to keep the plane from blasting down the moving runway and taking off. It doesn't say anything about the belt matching the engine speed. Just the plane's speed which says right there that it's moving which would give you a wheel speed of only a few hundred miles per hour WORST CASE SCENARIO which isn't going to cause anywhere near enough friction to bother the plane.

It's also right in the question that the conveyor is being matched to the plane's speed and not vice versa.

[The Goat]

Damnit, am I correct in my assessment above? I'm nearly positive that I am.

[Dammit!]

it really all depends on how you look at it.

if the belt is doing 500...and the wheels are freespinning, the plane can take off. TRUE

if the belt is doing 500...but the wheels are not spinning, and the plane is doing 500 mph in reverse, the plane likely won't be able to take off. IT WOULD BE FUN TO WATCH

if the belt is freerolling...the plane takes off. TRUE

if the belt doesn't move at all...the plant takes off. TRUE Edit: wait a second... the plant? What kind of plant? :lol:

if the second option is tried...it's likely a few people will die. VERY TRUE

:lol: :w00t:

[Jason Hall]

If they slow the plane down to match the conveyor speed, then the plane will not lift off. In that case the extra thrust that the plane does have makes no difference. I guess we will be wrong, because mithbusters won't be using enough thrust to make the plane overcome the conveyor's speed. I guess I should have made sure I understood the exact wording of the riddle.

[The Goat]

thanks, I wasn't sure if i was missing some key detail or not. lol.

[dogger]

actually I'm suprised nobody hit on the real problem here WERE ARE THEY GOING TO FIND A CONVOYER THAT IS LONG ENOUGH TO GET A PLANE UP TO SPEED.thing about it the plane is going to be moving forward unless it's teatherd which defeat's the purpose. a plane needs so much room to take off. in most cases several thousand feet. the whole time the plane is throttled up it's going to moove foward regardless of what the conveyor is doing. it'll run right off the end of it.

[Banage]

If its on a moving belt, only the trires are spinning. There is no air flow, so no lift.

[Red Rider]

actually I'm suprised nobody hit on the real problem here WERE ARE THEY GOING TO FIND A CONVOYER THAT IS LONG ENOUGH TO GET A PLANE UP TO SPEED.thing about it the plane is going to be moving forward unless it's teatherd which defeat's the purpose. a plane needs so much room to take off. in most cases several thousand feet. the whole time the plane is throttled up it's going to moove foward regardless of what the conveyor is doing. it'll run right off the end of it.I would imagine they will scale the experiment down by using a R/C aircraft.

[Billy Golightly]

Very true. They're gonna get roasted if they screw this one up though.

Here's the original question with the original wording for those that have not seen it.


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). Can the plane take off?"


The answer is in the question. The plane is moving forward. The rolling resistance of the wheels isn't going to do **** to keep the plane from blasting down the moving runway and taking off. It doesn't say anything about the belt matching the engine speed. Just the plane's speed which says right there that it's moving which would give you a wheel speed of only a few hundred miles per hour WORST CASE SCENARIO which isn't going to cause anywhere near enough friction to bother the plane.

It's also right in the question that the conveyor is being matched to the plane's speed and not vice versa.




I understand what your saying Dammit, but I'm just getting a different interpretation of the questions.


Chronologically:

The plane is sitting still (first 4 words)
The plane moves, while the conveyor moves in the opposite direction (so the plane does not start moving before the conveyor.)
The conveyor tracks, and matches the speed of the plane. (As thrust is increased, so is the speed of the airplane, also speeding up the conveyor :))

[Dammit!]

"the plane moves in one direction"

Dude the plane is moving. :lol: Standing still is not a direction. The question doesn't mention anything about matching thrust. Just the plane's speed. The plane can't have any speed if it's not moving.

It's not a myth it's a trick question. Either that or a horrendously constructed question. By the preview I think even the mythbusters might have gotten taken in by it. If you only read what's in the question without making assumptions about it's meaning, the plane moves and takes off. If you only use enough thrust in the plane to match the speed of the conveyor (as it appears the mythbusters may have done) then you're not doing what the question asks at all. I hope they're not that retarded.

Look on youtube, the preview is on there and it shows how they used a real airplane. Several people have done scale experiments on youtube. The model planes need very little thrust to break the friction of the wheels/bearings sitting still. Once that friction is broken the plane can accelerate at will and is not affected by the treadmill at all. They can keep pace with the treadmill even as it accelerates without even increasing thrust much if at all.

It's also right in the question that the initial friction is broken other wise neither the plane or the treadmill would be moving so don't go there. :lol:

[Red Rider]

I hope the Mythbusters used a strong enough tarp for their conveyor belt. I envision the friction between the airplane's wheels & the pavement wearing a hole right through that tarp.

[SWIGIN]

the way i always heard this was that the plane only uses enough thrust to stay still on the belt.

now, i dont care if the belt is going 1000 mph if the plane has no wind for lift it will not take off

[Billy Golightly]

The plane moves in one direction, while the conveyer moves in the opposite direction.


This to me insinuates that the plane and the conveyor both have started "moving" at the same time. It doesn't say, the plane moves and then they conveyor comes on, it says WHILE.

[Lomax]

The planes engines should not be affected by the conveyor belt regardless of speed. Imagine if you were standing on a treadmill with a pair of roller skates on. No matter how fast the treadmill or you moved you would/could remain in the same spot. Now in the same situation, imagine you have both your arms out like plane wings, if someone on each side of you grabbed your arms and gave you a consistent push would you not move forward? Of course you would because the energy that caused you to move forward did not have any resistance. A conveyor belt cannot slow the plane because the plane isnt driven by its wheels.
-Will

[Billy Golightly]

But what happens if the conveyor belt speeds up at the same time your pushed? :)

[Kintore]

The planes engines should not be affected by the conveyor belt regardless of speed. Imagine if you were standing on a treadmill with a pair of roller skates on. No matter how fast the treadmill or you moved you would/could remain in the same spot. Now in the same situation, imagine you have both your arms out like plane wings, if someone on each side of you grabbed your arms and gave you a consistent push would you not move forward? Of course you would because the energy that caused you to move forward did not have any resistance. A conveyor belt cannot slow the plane because the plane isnt driven by its wheels.
-Will

Best example yet, I think the exact same thing. Wheels got nothing to do with it, all about air thrust outa the engines, itll go!

[Dammit!]

the way i always heard this was that the plane only uses enough thrust to stay still on the belt.



And where did you hear that? I posted the original question and it does not say that.


The plane moves in one direction, while the conveyer moves in the opposite direction.


In your example the plane is not moving at all. It's standing still. That is not what the question says. The question says the plane moves in one direction. It does not say the engines are pushing in one direction while the treadmill goes in the other direction. It says the plane moves in one direction.

Taken literally without interpretation, the plane moves just as the question says, and takes off.

If the question said that the treadmill speeds up equally to the plane's THRUST, it would be a completely different question (and in which case I still think the plane would take of normally because it's been shown that planes need extremely low thrust to keep up with an excellerating treadmill once rolling resistance is broken and can speed up at will very easily).

If it said the plane's thrust is only used to equal the speed of the treadmill, it would be a completely different question (in which case it would be stationary and not lift off because there's no wind).

Don't feel bad though it looks like the mythbusters might have screwed it up too. :lol:

[Billy Golightly]

I still don't think the plane is actually moving (IE, airspeed) though Dammit. It says in teh first 4 words its sitting still, and then it says while the plane moves in one direction the conveyor moves the opposite at the same sped. I'm just taking that meaning. And I also get what your saying about the question saying the speed of the conveyor and plane are linked, not the thrust, but to me the thrust makes the plane move, so if the plane moves or even tries to move, the conveyor does it the exact opposite.

[Dammit!]

I still don't think the plane is actually moving (IE, airspeed) though Dammit. It says in teh first 4 words its sitting still, and then it says while the plane moves in one direction the conveyor moves the opposite at the same sped. I'm just taking that meaning. And I also get what your saying about the question saying the speed of the conveyor and plane are linked, not the thrust, but to me the thrust makes the plane move, so if the plane moves or even tries to move, the conveyor does it the exact opposite.

It's moving! For the question to mean what you're saying it would have to be worded completely differently. Of course in the begining it's sitting still. What else would it be doing? If it meant what you're saying it would not say while the plane moves, it would say while the plane increases thrust. BUT IT DON'T SAY THAT HOMIE! :Bounce :Bounce :Bounce :w00t:

Even if it did say that, the plane can still easily overcome anything the treadmill is doing. The wheels and bearings offer very little resistance once they're rolling and they have to be rolling in any version of the question. Look at the vid I posted. The dude had to throttle up a little to break the friction when the treadmill was first started but once he did he had to throttle back to keep the plane on the treadmill. He then speeds up the treadmill without even having to increase thrust on the plane at all.

The only version of the question where the plane doesn't fly is if the thrust is only used to equal the speed of the treadmill. If that's the version the mythbusters test it will be a case of monumental stupidity because any idiot knows that if the plane is sitting still it isn't going to fly.

[oOGoFastOo]

yes, it doesnt matter if the treadmill matches the speeds of the plain because aLL IT WOULD DO IS MAKE THE PLAINS WHEELS SPIN FASTER AND WOULDNT STOP THE PLAIN because the plain is pushing off the air and not the treadmill. there fore the plain would have to be in a wind tunnel that would mach it to be stopped and then it would still take off because the wind would create lift, this question is retarded, think about it.

[The Goat]

spelling or not...GoFast has said it. the only thing the conveyor belt would do would be make the wheels spin faster...the only way it would move the plane at all, is if they put on the brakes.

[SWIGIN]

i dont think anyone thinks the belt it moveing the plane at all.

but if you run in the oposite direction on a belt (going the right speed) you would apear to be not moving....or standing still running in place

this is what the myth is about as i first heard it


the plane will be throtled up some to keep still while on the belt.......no lift can happen

[SWIGIN]

i also dont think anyone is saying if the belt was as long as a runway the plane wouldnt take off.

of couse it would take off since the thrust would move the plaine like in dammits video....but thats not the original myth

[Dammit!]

I want to find whoever first wrote this stupid question and beat them to death with a frozen turkey leg.

Lets just agree that the person who wrote it is a moron that made it far too ambiguous to determine wtf they were trying to ask.

The ORIGINAL question does not mention anything about the plane remaining stationary (in fact it says the opposite). Did he mean it that way? I don't know. If he did he sure as hell should have worded his question better. The way it's worded, the plane moves, therefore it takes off.

Here it is one more time in it's original form.


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). Can the plane take off?

In this case the plane takes off with ease. The conveyor is simply matching the plane's speed. It cannot have any speed if it's not moving. The conveyor can only have a maximum speed equal to twice the speed the plane needs in order to lift off the way this is worded.

This right here is the important part of the question in it's original form.


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 conveyor is matching the speed of the plane and not the other way around! The plane cannot have any speed unless it's moving!

If the person that wrote the above intended to say that the conveyor is matching the THRUST of the plane's engines, it should have been worded like this.


A plane is standing on a runway that can move (some sort of band conveyer). The plane engines attempt to push the plane in one direction, while the conveyer moves in the opposite direction and accelrates relative to the plane's thrust. Can the plane take off?

The answer is still yes. The plane can easily take off. The plane's thrust will equal some set speed of which I have no idea but the thrust of the engines will easily defeat the very low friction created by the free spinning wheels.

Here's how it should have been worded if he meant the plane is stationary.


A plane is standing on a runway that can move (some sort of band conveyer). The conveyor moves in one direction while the plane uses it's engines to match the speed of the conveyor (in effect keeping the plane in a stationary position). Can the plane take off?

The answer here is no and **** you for asking such a stupid question. :lol:

[SWIGIN]

BWAAAAAAAHAHAHAHAHAHA



werd!!

[smokinwrench]

You guys are reading way to deep into this.

When the plane is on the conveyer belt it will not be moving. Conveyer speed will be really high to attempt lift but actuall ground speed will be ZERO.

As the plane engine thrusts it forward the conveyer will also increase equally to make sure the plane stays stationary.

Some guys still haven't voted!

[Dammit!]

You guys are reading way to deep into this.

When the plane is on the conveyer belt it will not be moving. Conveyer speed will be really high to attempt lift but actuall ground speed will be ZERO.



Find in the original question where it says the plane remains stationary. It doesn't say that anywhere. It says the plane moves and the belt matches it's speed in the other direction. That's what it says. By saying the plane doesn't move you're changing the question to fit your answer. It says the plane moves. It says the belt matches the plane's speed. The plane can't move and it can't have any speed if it's sitting still.

If the myth is "can a plane take off without moving by getting the wheels turning really fast on a treadmill" then it's the dumbest myth ever and not even worth busting. That's no different than asking if you tie a plane to a massive pole and blast the engines, will it take off (no it won't and anybody that thinks it will is more retarded than the guy that asked the question in the first place).

A treadmill will not keep the plane from moving forward no matter how fast the belt is spinning. The only way the plane will remain stationary on a conveyor belt is if they're basically idling the engines on the belt and not attempting to bring the engines up to normal take off thrust. If they accelerate the engines to normal take off thrust, the plane is going to to take off just like it normally would regardless of how much the treadmill accelerates.

See my last post before this one. Whoever wrote this crap should be publicly stoned to death. If it's intended to ask if a plane will fly without moving through the air, it's a poorly worded question based on a flawed premise.

I want to kill the guy that wrote it. Seriously.

[Chevy200s]

EDIT, didnt see dammits post while I was typing, he's saying exactly the same thing as I am, someone has to prove that the plane wont move on the conveyer

This is something interesting I found, he raises a good point with the gear being frozen. I got this from http://www.newton.dep.anl.gov/askasci/phy05/phy05023.htm

"How about if the wheels were frozen and not turning? Even with
this, I would bet an F-15 would get of the ground. You only need to
keep thrust greater than friction to allow the acceleration over the
surface until flying speed is obtained.

Larry Krengel
(Who has landed with a main gear frozen and wished he had your
conveyor belt on the runway.)"

I think whats getting everyone here is that they assume that just because the belt matches the speed of the plane in reverse somehow that means the plane wont move forward. If for some reason this happened and the plane could remain stationary then yes there would be no airflow around the wings, no changes in pressure and the wing would not lift. The thing is that the plane would still move, the wheels are free wheeling.

Think of taking off from a seaplane like mentioned where the waves are going the opposite direction, other than being a lot more bumpy, having more drag and not being as precise and controllable, its a similar concept.

If you guys are interested in this and want to learn about some similar real life examples or just interesting take off methods read about the track used to get the Wright Flyer to lift off, and also about the Lockheed D-12/M-21 lauches of the 1960's. The D-12 was basically an SR-71 that carried a drone on its back. Once the D-12 got up to around Mach 3, the M-21 Drone would take off from the back, gain altitude and speed up to Mach 4 and carry out its mission. While its not the same situation at all, some might even think big deal its just launching a really big missle, the technological feats of doing something like this to me are amazing, especially considering that they were doing this with 1960's computing power and technology. and hey to be honest I just think this stuff if really cool and figured this would be the only time I could get away with talkin about it on 3ww :lol:

heres a pic of the D-21
http://www.habus.org/revealed/pics/a12drone1.jpg

Regardless of what happens on myth busters I have an RC plane that I wouldnt mind trying this with, I'm just trying to think of the best way to simulate the conveyor belt as I dont have one lying around, and also it would be tough to match the speed to the plane. All that I'm looking to prove is that it will move. even something as simple as pushing an object on wheels with little to no resistance against the direction of the belt would be a good model.

Oh and another thing, is this whole debate concerning a jet or can it be a prop plane? I doubt the prop wash would yeild enough airflow across the wing for liftoff on a regular plane, but hey if your allowed to create this goofy unconventional moving runway seems like it would be allowable to put a huge prop on a small plane. oh well I just burned up way too much typing all this myth busters will probably mess up but it will be interesting to see

[Dammit!]

http://www.straightdope.com/columns/060203.html

[Lomax]

But what happens if the conveyor belt speeds up at the same time your pushed? :)

It doesnt matter, I am not sure if you have a treadmill laying around but if you do try something. Find a skate, or a bicycle or something that has a wheel, hub, and bearings. Roll it around and see how it feels, basically the resistance your item gives you when attemting to be pushed. Set it on the treadmill and turn it up all the while doing no more than holding it in place. Now attempt to push it forward on the treadmill. Its not much (if any) more difficult to push it right off if you wanted to is it? Now i know that the treadmill cannot match the amount of force that you can apply, what i am trying to suggest is regardless of what the treadmill is doing speed wise, since the type of energy you are applying is not driving the wheel but rather pushing it, the actual speed of the wheel doesnt matter.
Another way i suppose is if you can get a hot wheel to stay on a treadmill while it is moving, tape a few bottle rockets to it and see if it doesnt fly right into the wall.
Since the wheel isnt producing the power like a car, There isnt much that the treadmill can do other than offer a slight resistance and perhaps some cooked wheel bearings from spinning 1000 mph.
-Will

[ProCarbine2k1]

Unless I missed something in the last couple of pages, it would be possible for the place to fly, obviously not stationary. The ground speed in this scenario means NOTHING, it really doesnt matter if the treadmill is moving or not; it has everything to do with airspeed, and without replicating that- the plane will take off just as it would without a treadmill, regardless of treadmill speed, it will still fly at realtime mph.
I guess what I am trying to say is that the treadmill could be moving at 50 mph, and they could set the plane to propel at 5mph, and the plane would move forward at approx. 5mph with wheels turning at 55mph(aside from the resistance of force, not the speed the treadmill would produce.) Dont know of a better way to explain it, hopefully the results will show the same! (I think some of their experiments are VERY INNACURATE to a real world scenario.)

[Jason Hall]

Here's a couple more thing's I have been thinking about that could screw the entire thing up. What happens If they use a remote control plane and the conveyor Is not long enough or Is elevated off the ground surface. In that case the plane won't have enough air speed to lift off and will fall to the ground level. There are so many ways that this stupid question can be played out. If they do the test exactly like the question Is worded, they will have to have a conveyor that Is long enough for the plane to lift off. If they hold the plane speed back to the limit of the conveyor It will not be done as the question Is worded. The question asks will the plane fly? That means they have to give the plane enough room to gain Its speed while the conveyor goes the oposite direction at the same speed. The plane will move forward, and as long as the conveyor Is long enough the plane will gain enough air speed and lift off.

[Chevy200s]

The plane will move forward, and as long as the conveyor Is long enough the plane will gain enough air speed and lift off.

thats exactly it, if the conveyor isnt long enough it wont be able to get up to speed. however I think that just the plane's ability to move forward should be enough to change most people's minds, at least on this website. if the plane can move itself forward towards the end of the belt then I would say all that is stopping it from take off is the length of the run way.

[Dirtcrasher]

I hope it doesn't plop off the conveyor and explode!!

Anyhow, I voted yes. The thrust from the rockets will force the plane away from the air behind it and it will take off. Hopefully before it reaches the end of the conveyor.

The wheels don't drive so I think a spinning conveyor does nothing. So if we ran a conveyor in the opposite direction on a landing would the plane stick it the second it hits the convetor? I doubt it.

When is this going to air? Please don't make me read every reply, LOL!!

EDIT 9PM EST......

[WLL]

the convayer will do nothing to keep the plane on the ground. wheels dont make a plane fly:crazy:

[Billy Golightly]

mythbusters interpretation of it will be on shortly...should be interesting.

[Dirtcrasher]

I hope they try this with a real plane with about a 10000' runway....

I though it was gonna be a jet - I'm watchin!!!!!

[Bryan Raffa]

crap I missed it............should have set the DVR.. oh wow I actually cought it ...im watchin

[Bryan Raffa]

Bah..................myth Busted!

[Billy Golightly]

Well its difficult to argue with their results. BUT :D I'm inclined to believe that the rolling resistance would have played a bigger part on a 747 then it would have on a 300lbs ultra-light. I would like to have known mathematically, how fast the conveyor would have had to turn before the ultralight wasn't able to overcome the resistance, and then calculate that towards the weight (and power, too) of a 747 and atleast see how fast it would have had to turn to make it not take off from the resistance.

[Bryan Raffa]

but they would have needed to use a chevy if they tryed that with a 747:D

[Jason Hall]

So what happend, I still don't know. I take It the plane must have lifted off?

[Bryan Raffa]

yes it took off

[Jason Hall]

Thanks Raffa, I could'nt watch It :wondering

[Bigbore]

It took off BUT it wasn't done right. The ground speed of the plane was faster than the speed of the conveyer. You could see the plane moving forward. If the planes speed was matched by the conveyer, making the plane stationary there wouldn't be any air passing over the wings to create lift.

[hondahaulic]

if the plane's speed and the conveyer speed were perfectly equal and opposite, the plane isnt going to care what the conveyer speed is. The plane is going to be moved forward from the thrust from the engines.

[hondahaulic]

the only thing on the plane that the conveyer will effect is the wheels. The only purpose of the wheels on the plane is to reduce friction. the wheels have nothing to do with the actual propulsion of the plane. Whether on a conveyer or not, the wheels will still reduce friction just like their supposed to, no matter which way or how fast they spin.

the planes propeller (or jets) move the plane forwards. The wheels are still going to eliminate friction whether on a conveyer or not. The propeller is also still going to propel the plane forward, so the plane will NOT STAY STATIONARY. it will move down the conveyer runway and take off.

[Jim mac]

the whole question is the plane is going the opposite direction from the conveyor at the same speed. So the plane is sitting still, not being moved backwards or forwards. will it fly? Of course the plane flys if it moves forward on the conveyor. thats because you have airflow over and under the wings. but the original question still stands. will the plane fly sitting stationary on the treadmill? They still havent done that yet. Jim

[Chevy200s]

but they would have needed to use a chevy if they tryed that with a 747:D

agreed:lol: :w00t:

[Dammit!]

I can't believe people still can't see the light.

1) that plane only needed to hit 25mph to take off. The truck hit that speed with ease. It didn't bother the plane one bit. It wouldn't have bothered the plane if it were doing a hundred miles an hour. It wouldn't bother a jumbo jet either (if a suitable coneyor belt could be made for one).

2) There is no conveyor belt in existance or concept that can accelerate to the point of keeping a plane from moving due to friction on the wheels/bearings. Any such device has no basis in reality and would be nothing but theory.

3) The question does not say ANYWHERE that the plane is not moving forward. It says exactly the opposite. It says the plane is moving and the belt is matching it's speed in the other direction. It does not say the belt is matching the plane's thrust. For ****'s sake this is basic reading comprehension. It was a trick question.

Yes I'm being a ****. I still want to kill the person that wrote that *** damn question. I want to wrap my hands around their throat, watch the life drain from their body and eat their soul.

This is my last post on this subject here or anywhere. The plane moves. The plane flies. Period. Deal with it. The "myth" was never about a stationary plane. If it was it wouldn't be a myth or a trick question at all. What *Edited**Edited**Edited**Edited**Edited**Edited**E dited* would think a plane that isn't moving would fly? I know 3rd graders that wouldn't fall for that. :D

Thank you ladies and gentlemen good night we love you all! :lol:

[69HemiGTX]

I can't believe people still can't see the light.

The last time I checked, 11 people had voted no before the show aired. Three more votes were cast between then and the show. It's obvious that there are some here, at the very least the 14 brave enough to vote, who need to go back to high school physics class. :rolleyes:

[johnny's X]

Physics? who took that class in high school. I majored in wood and metal shop :beer.

[smokinwrench]

Physics? who took that class in high school. I majored in wood and metal shop :beer.

Yep we majored in the same classes.


I say Myth Busters ruined the entire show by allowing the plane to move. I sure am glad Dammit will not post on this thread again because he read the question the wrong way and read to far into it.:beer

[SWIGIN]

i voted no since the way i first heard this myth over a year ago it said that all the plane was doing was useing just enough thrust to stand still and the belt was going ...say....100mph

now we all know that it will just sit there till it runs out of gas before it lifts off

so since this is the oldest and first version of the myth i heard and normaly they go with the original myth...i voted no

[hrc200x]

For those that didn't see the show even the pilot that was in the plain on the converyor belt didn't think he'd fly, he was very surprised.

Their first scaled down model didn't seem like it was done right, they got the conveyor up to speed before the planes prop was even turning, they throttled up the plane and it went forward on the belt no problem, just the belt was to short in that test.

I voted yes before the show aired.

[200xcellent]

The planes propeler moves the plane relative to the AIR not the ground, so no matter how fast the conveyer is going it will never hold the plane still NEVER! If the plane uses any thrust at all it will move forward because its moving the air!

[SWIGIN]

your wrong....look at the links posted

[Bigbore]

Call the Navy and let them know that they can get rid of the catapults on the aircraft carriers since they don't need to get a high rate of ground speed to get the plane to take off, ALL they need is a conveyer system.:lol:

[200xcellent]

im pretty sure the plane took off so how can i be wrong? havent you guys ever heard of planes lifting off while parked only due to very high wind gusts?

[The Goat]

Physics? who took that class in high school. I majored in wood and metal shop :beer.

i took calculus and physics so I would haven't to take art class or have a PE class at the ass crack of dawn my senior year.

[Jason Hall]

The plane Is moving forward, compaired to something In the backround, not In compairison to the conveyor!!! The plane Is moving, UnLike a house or a parked car or something stationary. Although the conveyor Is being moved the oposite direction at the same speed as the plane It will just move the planes wheels. The reason the plane Is not moving the same way as the conveyor Is because the thrust from the engine Is overpowering the drag from the wheel bearings. If you put the brakes on, the plane would ride the conveyor backward. Then the plane would need ALOT more thrust to drag the wheels making the front of the plane dive down. Just Imagine a HOVERCRAFT, It has no wheels. It could be propelled forward If a conveyor was under It. That Is basically what Is happening In this question. As the question states, the plane Is moving. It Is moving foward from the parked car that Is sitting along side but not on the conveyor. The conveyor Is moving backward to the parked car. The conveyor Is just spinning the wheels 2 times as fast as the planes movement to the rest of the non moving things near the conveyor (parked car, a house, the control tower at the airport, the guy standing along side the conveyor, a dog taking a crap In the lawn In the grass along side the runway that the conveyor Is set up on :w00t: :w00t: :w00t:


The plane Is moving 1st, then the conveyor Is spinning the planes wheels In the oposite direction at the same speed of the planes movement compaired to the rest of the still standing world.

[Billy Golightly]

A 747 is sitting on a runway....:lol:

[Bryan Raffa]

so in all.. the wheel's are spinning faster than they normaly would spin..and the plane simply takes off,,like on the show...if the coveyor matches the speed of the plane..the wheeles are spinning twice as fast as normal..

[Jason Hall]

YES!!!! 1. The plane Is sitting on the runway/conveyor. 2. The plane Is moving forward. 3. The conveyor matches the planes speed In relation to the reast of the non moving world. 4. The conveyor SPINNS the planes wheels at twice the normal rate of speed. 5. The plane Is pushed forward with thrust from the engine's moving air. 6. The plane lifts of the ground because of air going over the wing's creating lift.


The conveyor can't match the speed of a plane that Is sitting still. The plane has to move In refrence to something still In order to measure the speed. Then the conveyor can match the speed of the planes movement.

[Yamada]

Everyone that voted yes take a :beer or two. :D And for those off you that voted No, take some more to calm down.:lol:

[Gag_Halfront]

Methinks we have some red-board hold outs.

[ausatc70]

as long as the conveyor matches the planes speed.
no air flow over wings=no lift=no flight! simple

[Red Rider]

as long as the conveyor matches the planes speed.
no air flow over wings=no lift=no flight! simpleAre you sure? Better think about it again.

[PaTriker]

I think I saw this on Myth Busters and it worked. Did anyone else see this?