NationStates Jolt Archive

The Mythbusters are testing whether or not a plane on a conveyor belt will take off. Tune in now for epic answers!

Didn't we have a massive thread about this a few months ago?
But it didn't have Mythbusters or planes and conveyor belts.

Didn't we have a massive thread about this a few months ago?

Didn't we have a massive thread about this a few months ago?

That is a question, and is not allowed, you must not have seen the thread title... there are no more questions allowed... by anyone... ever.

Because apparently a plane on a conveyor belt is that grand.

Tune in now for epic answers!

You should just tell me the results. I would find it easier.

I did not see the previous thread and would like a link if one could provide one.

Anyway I would bet $1000 that a plane can take off from a conveyor belt moving against the direction of the plane. The reason is that a plane uses lift to take off not the speed of the wheels turning against the ground. You may need to provide a bit more thrust to the engines but it would still take off because of lift. The wheels will spin obviously much faster as a result of the conveyor belt but it would not have a major effect on the airplane lifting off the ground.

Oh, I'm sure we could make it work somehow, but I wonder whether it would be cost efficient to utilize conveyor belts regularly, they couldn't be easy to set up. It also raises the issue of where a plane would land if an airport used only conveyor belts.

I did not see the previous thread and would like a link if one could provide one.

Anyway I would bet $1000 that a plane can take off from a conveyor belt moving against the direction of the plane. The reason is that a plane uses lift to take off not the speed of the wheels turning against the ground. You may need to provide a bit more thrust to the engines but it would still take off because of lift. The wheels will spin obviously much faster as a result of the conveyor belt but it would not have a major effect on the airplane lifting off the ground.

I thought that whole thread was about planes and conveyor belts?

Although, knowing NS, it might have been derailed.

Hey! didn't I just get done telling you that questions are not allowed!

I'm sorry, I'm being ridiculous, it was just a hilarious misuse of a thread title.

I did not see the previous thread and would like a link if one could provide one.

Anyway I would bet $1000 that a plane can take off from a conveyor belt moving against the direction of the plane. The reason is that a plane uses lift to take off not the speed of the wheels turning against the ground. You may need to provide a bit more thrust to the engines but it would still take off because of lift. The wheels will spin obviously much faster as a result of the conveyor belt but it would not have a major effect on the airplane lifting off the ground.

I see this question all the time, and my opinion is that it cannot. Partly because the aircraft is in essence, stationary when being viewed by an external source. And not to mention that lift is generated due to an object moving through a stationary fluid or vice versa. In this situation, both fluid and object are stationary, so there can be no lift. But if the engines could overcome the opposite forces of the conveyor built, it would just be a really inefficient runway :P, as a large percentage of thrust goes into that. Maybe that's why take off assists push the aircraft in the direction it's going rather than the other way.

But it didn't have Mythbusters or planes and conveyor belts.

I thought that whole thread was about planes and conveyor belts?

Although, knowing NS, it might have been derailed.

The Mythbusters are testing whether or not a plane on a conveyor belt will take off. Tune in now for epic answers!

They just got done ... guess what it did :eek:

No not really surprised, Like Jamie said at the end; for some reason people can not wrap their head around the fact that power is applied to the air not wheels and the wheels have no effect rather then reducing friction

Didn't we have a massive thread about this a few months ago?
yes (http://forums.jolt.co.uk/showthread.php?t=541295)

But if the engines could overcome the opposite forces of the conveyor built, it would just be a really inefficient runway :P, as a large percentage of thrust goes into that. Maybe that's why take off assists push the aircraft in the direction it's going rather than the other way.

The thrust that a modern Jet can put out on takeoff I believe could easily overcome a runway conveyor belt going against that planes wheels.

I just watched the plane take off quite easily from the conveyor belt.

They just got done ... guess what it did :eek:

No not really surprised, Like Jamie said at the end; for some reason people can not wrap their head around the fact that power is applied to the air not wheels and the wheels have no effect rather then reducing friction

Exactly.

So, I just finished watching Mythbusters tonight, and they tested the myth that a plane won't take off from a conveyor. They busted the myth with an ultralight airplane and a conveyor made out of canvas tarp pulled by a truck, and the plane took off like normal. Myth BUSTED! :D

So, are you convinced? I was before the episode, so it didn't affect me. But it hopefully convinced the skeptics.

So, I just finished watching Mythbusters tonight, and they tested the myth that a plane won't take off from a conveyor. They busted the myth with an ultralight airplane and a conveyor made out of canvas tarp pulled by a truck, and the plane took off like normal. Myth BUSTED! :D

So, are you convinced? I was before the episode, so it didn't affect me. But it hopefully convinced the skeptics.

so the plane had a groundspeed of ZERO and took off?

So: why does a fly in the cabin of a car not get smashed against the back windshield when the car is traveling at 70mph on the highway? ;)

Yeah. Apparently airspeed counts for a lot more than groundspeed with airplanes.

so when it started to take off did it go straight up? how did it accellerate from zero to flying speed?

so the plane had a groundspeed of ZERO and took off?

Yeah. Apparently airspeed counts for a lot more than groundspeed with airplanes.

So: why does a fly in the cabin of a car not get smashed against the back windshield when the car is traveling at 70mph on the highway? ;)

If you had all the windows down in an instant it would be smashed against the back windshield. :)

so when it started to take off did it go straight up? how did it accellerate from zero to flying speed?

All that has to happen is that the wheels lift off the surface.

Edit: Accelerating from zero to flying speed is normal only the wheels spin faster then normal. Maybe a bit more thrust to compensate for the slight drag from the wheels.

All that has to happen is that the wheels lift off the surface.

yes but as the wheels lift straight up off the surface, the plane is flying at zero miles per hour. it then has to travel forward at some speed to maintain flight. so the speed up from zero to whatever ultralights can fly at has to take some amount of time however small.

how did that go?

so the plane had a groundspeed of ZERO and took off?

No the plane had normal ground speed, and double speed relative to the belt

yes but as the wheels lift straight up off the surface, the plane is flying at zero miles per hour. it then has to travel forward at some speed to maintain flight. so the speed up from zero to whatever ultralights can fly at has to take some amount of time however small.

how did that go?
It was not going 0 it was going the 20 something MPH forward relitive to the air\ground that is nessisary for the ultralite to take off

yes but as the wheels lift straight up off the surface, the plane is flying at zero miles per hour.
No, it’s flying a whatever speed the conveyor belt was travelling, relative to the stationary ground beside it. (I imagine there’s a minimum speed the conveyor belt must travel at before the wings generate enough lift.)

Yeah. Apparently airspeed counts for a lot more than groundspeed with airplanes.

Groundspeed was normal in this case ... just double speed relative to the belt. Everything else was normal

so when it started to take off did it go straight up? how did it accellerate from zero to flying speed?

what do you mean by "straight up"? nose pointed completely vertical? or simply that the plane moved in a purely vertical fashion when first lifting from the belt?

The plane was accelerating the whole time. It was only the wheels that were caught at zero.

Why?

Lots of air pushing it back?

what do you mean by "straight up"? nose pointed completely vertical? or simply that the plane moved in a purely vertical fashion when first lifting from the belt?

The plane was accelerating the whole time. It was only the wheels that were caught at zero.

as i understand it the plane had an effective speed of zero. meaning that all the air that was passing over its wings to generate lift came from its one little propellor.

so its not moving, in essense, but as its wheels leave the ground it IS moving, suddenly, relative to the ground. it goes from NOT moving relative to the ground to moving relative to the ground.

so its starting to fly at a speed of zero. then it speeds up as its propellor continues to drag it through the air.

was it a smooth beginning? how fast a speed does an ultralight have to maintain in order to fly?

It was not going 0 it was going the 20 something MPH forward relitive to the air\ground that is nessisary for the ultralite to take off

was it moving relative to the solid ground underneath the tarp?

If you had all the windows down in an instant it would be smashed against the back windshield. :)

Why?

You think Ashmoria was using the term groundspeed in the technically correct sense? I suppose she may have been, but I didn't assume so.

i want to know if the plane was actually MOVING or if it was still except for the moving propellor and wheels. if i was standing next to it on the tarmac (or where ever they were) would it be moving away from me?

You think Ashmoria was using the term groundspeed in the technically correct sense? I suppose she may have been, but I didn't assume so.

True :)

Groundspeed was normal in this case ... just double speed relative to the belt. Everything else was normal

You think Ashmoria was using the term groundspeed in the technically correct sense? I suppose she may have been, but I didn't assume so.

i want to know if the plane was actually MOVING or if it was still except for the moving propellor and wheels. if i was standing next to it on the tarmac (or where ever they were) would it be moving away from me?
Yes; it’s on a conveyor belt which is propelling the aircraft away from you.

However, if you were standing on the conveyor belt also, then relative to yourself the plane wouldn’t be moving.

That’s where I think most of the confusion pops in.

Yes; it’s on a conveyor belt which is propelling the aircraft away from you.

However, if you were standing on the conveyor belt also, then relative to yourself the plane wouldn’t be moving.

That’s where I think most of the confusion pops in.

The aircraft is accelerating forward relative to the belt too ... Twice as fast actually

thank you for the answer

now that i find that i have completely misunderstood the problem, i wonder why anyone would think that it matters HOW the plane got to a speed that is fast enough for it to take off.

That's a good question to ask of people who were there and able to experience it firsthand. E-mail the Mythbusters and pose your question to them. It'd be interesting to see the response.

I believe they had said that the airplane moved forward relative to the cones that were stationary on the runway when explaining it as well ... I was distracted by some work though and was not watching just listening at that point

That's a good question to ask of people who were there and able to experience it firsthand. E-mail the Mythbusters and pose your question to them. It'd be interesting to see the response.

ut o

does that mean that as far as YOU can tell the plane would have been standing still next to me on the tarmac with only the propellor and wheels moving?

i want to know if the plane was actually MOVING or if it was still except for the moving propellor and wheels. if i was standing next to it on the tarmac (or where ever they were) would it be moving away from me?

That's a good question to ask of people who were there and able to experience it firsthand. E-mail the Mythbusters and pose your question to them. It'd be interesting to see the response.

That's a good question to ask of people who were there and able to experience it firsthand. E-mail the Mythbusters and pose your question to them. It'd be interesting to see the response.

I don't think it was moving at all relative to the ground - that rather defeats the issue.

Here. (http://www.youtube.com/watch?v=KSBFQOfas60)

It appears the truck is not towing the plane nor the conveyor belt - it's simply maintaining the plane in a steady position much as they stop the plane from rolling backwards on the toy model version.

Yes; it’s on a conveyor belt which is propelling the aircraft away from you.

However, if you were standing on the conveyor belt also, then relative to yourself the plane wouldn’t be moving.

That’s where I think most of the confusion pops in.

I suppose that makes sense as a source of confusion. My only confusion was about why folks thought it couldn't be done. It never even occurred to me that a plane would have trouble taking off from a conveyor belt.

I don't think it was moving at all relative to the ground - that rather defeats the issue.

Here. (http://www.youtube.com/watch?v=KSBFQOfas60)

It appears the truck is not towing the plane nor the conveyor belt - it's simply maintaining the plane in a steady position much as they stop the plane from rolling backwards on the toy model version.

i cant look at video.

so im standing beside the ultralight and its not moving. all that is moving is the propellor and the wheels going at about 20 mph? the only air moving over the wing is the air from the propellor. right? if its not moving over the ground its also not moving through the air.

at a certain speed of those wheels turning around the plane starts moving UP? going from an effective speed of ZERO it starts to fly?

is that what ill see if i should ever get to watch the video? (minus me standing next to it of course)

ut o

does that mean that as far as YOU can tell the plane would have been standing still next to me on the tarmac with only the propellor and wheels moving?

No. It just means that I don't really understand why it matters, and I didn't get a sense of how the plane was moving relative to stationary objects on the tarmac. I simply didn't watch for it, as it wasn't a factor I was interested in.

But the Mythbusters staff probably were watching for it, knowing them. So they could probably answer your question. :)

i cant look at video.

so im standing beside the ultralight and its not moving. all that is moving is the propellor and the wheels going at about 20 mph? the only air moving over the wing is the air from the propellor. right? if its not moving over the ground its also not moving through the air.

at a certain speed of those wheels turning around the plane starts moving UP? going from an effective speed of ZERO it starts to fly?

is that what ill see if i should ever get to watch the video? (minus me standing next to it of course)

It is moving forward at roughly 20 mph relitive to the ground and air

i cant look at video.

so im standing beside the ultralight and its not moving. all that is moving is the propellor and the wheels going at about 20 mph? the only air moving over the wing is the air from the propellor. right? if its not moving over the ground its also not moving through the air.

at a certain speed of those wheels turning around the plane starts moving UP? going from an effective speed of ZERO it starts to fly?

is that what ill see if i should ever get to watch the video? (minus me standing next to it of course)

No alas, the video is the teaser for Mythbusters where they show the set up.

If you're just placing the plane on a conveyor belt, towing that belt behind you and wondering whether the plane will take off then, well it's idiotic, you're simply replacing the airplane wheels with the conveyor belt wheels.

The question can only be of interest in terms of busting a myth when the plane is effectively stationary relative to the ground. the conveyor belt allows for thrust, not movement.

No. It just means that I don't really understand why it matters, and I didn't get a sense of how the plane was moving relative to stationary objects on the tarmac. I simply didn't watch for it, as it wasn't a factor I was interested in.

But the Mythbusters staff probably were watching for it, knowing them. So they could probably answer your question. :)

it matters if the plane is moving. a plane doesnt fly on the rotation of its wheels. it flies on the basis of air flowing over its wings as it moves through the air starting as it moves along the ground until it gets to a speed fast enough to generate the lift required to raise the particular aircraft invovled into the air.

it matters if the plane is moving. a plane doesnt fly on the rotation of its wheels. it flies on the basis of air flowing over its wings as it moves through the air starting as it moves along the ground until it gets to a speed fast enough to generate the lift required to raise the particular aircraft invovled into the air.

Correct and that is not effected by the belt at all

It is moving forward at roughly 20 mph relitive to the ground and air

No alas, the video is the teaser for Mythbusters where they show the set up.

If you're just placing the plane on a conveyor belt, towing that belt behind you and wondering whether the plane will take off then, well it's idiotic, you're simply replacing the airplane wheels with the conveyor belt wheels.

The question can only be of interest in terms of busting a myth when the plane is effectively stationary relative to the ground. the conveyor belt allows for thrust, not movement.


all i want to know is if the plane is moving relative to the ground.

you 2 seem to be giving me 2 different answers.

are you?

I don’t think it was moving at all relative to the ground–that rather defeats the issue.

Here. (“http://www.youtube.com/watch?v=KSBFQOfas60”)

It appears the truck is not towing the plane nor the conveyor belt–it’s simply maintaining the plane in a steady position much as they stop the plane from rolling backwards on the toy model version.
Oh, I see. My apologies to Ashmoria.

That’s an entirely different problem.

all i want to know is if the plane is moving relative to the ground.

you 2 seem to be giving me 2 different answers.

are you?

Clearly :)

I'm no physicist though so I could be wrong - it just doesn't make sense to me to place a plane on a treadmill and see if a plane is taking off when the treadmill is simply acting as the wheels for the plane.

Why?

Hmmm... I have a feeling I am getting set up here.

But I would say off the cuff that the speed of the airflow coming through the open windows would send it into the back window. However I think it would have to be instant windows down for it to provide enough force to splat it.

They are purposely trying to mess with your head. ;)

i think they are doing it because they know that when i fly i pray to the "lift gods" to keep the plane in the air.

its all magic and everyone knows it.

all i want to know is if the plane is moving relative to the ground.

you 2 seem to be giving me 2 different answers.

are you?


They are purposely trying to mess with your head. ;)

No alas, the video is the teaser for Mythbusters where they show the set up.

If you're just placing the plane on a conveyor belt, towing that belt behind you and wondering whether the plane will take off then, well it's idiotic, you're simply replacing the airplane wheels with the conveyor belt wheels.

The question can only be of interest in terms of busting a myth when the plane is effectively stationary relative to the ground. the conveyor belt allows for thrust, not movement.

But an airplane will not stay stationary as the conveyer belt and wheels have nothing to do with the thrust or movement of the plane

They are purposely trying to mess with your head. ;)

Im not ... the simple fact of the matter is the belt has nothing to do with acceleration nor speed of the airplane (ground nor air)

But an airplane will not stay stationary as the conveyer belt and wheels have nothing to do with the thrust or movement of the plane

The inability of people to explain this clearly causes tremendous confusion and leads me to believe that they're simply parroting information they don't understand.

Not saying this is applicable to you but...

If you allow the plane to move relative to the ground, what's the point of the experiment? You're simply exchanging wheels - I understand the wheels have nothing to do with take-off but they do have something to do with the ability for the plane to move forward.

Simply placing the plane on sticks means the friction from the sticks will merely cause the plane to topple over given the thrust, hence you need a conveyor belt to offset that friction.

There's no difference in using a conveyor belt on wheels as opposed to normally on wheels.

it matters if the plane is moving. a plane doesnt fly on the rotation of its wheels. it flies on the basis of air flowing over its wings as it moves through the air starting as it moves along the ground until it gets to a speed fast enough to generate the lift required to raise the particular aircraft invovled into the air.

I'm aware of all that. But still not getting why it would stop an airplane from taking off from a conveyor belt or any other moving surface (like the deck of an aircraft carrier in WWII). Let's say our WWII fighter needs to hit 40mph to take off. If the aircraft carrier (and by extension the deck) is moving 40mph SW, and the airplane is moving 40 mph NE, why would the airplane fail to take off, given good weather conditions and a sound plane?

The inability of people to explain this clearly causes tremendous confusion and leads me to believe that they're simply parroting information they don't understand.

Not saying this is applicable to you but...

If you allow the plane to move relative to the ground, what's the point of the experiment? You're simply exchanging wheels - I understand the wheels have nothing to do with take-off but they do have something to do with the ability for the plane to move forward.

Simply placing the plane on sticks means the friction from the sticks will merely cause the plane to topple over given the thrust, hence you need a conveyor belt to offset that friction.

There's no difference in using a conveyor belt on wheels as opposed to normally on wheels.

Hm. Maybe this is why I can't understand why folks would think a plane would have problems taking off from a moving surface. I'm just not seeing much difference between using wheels and a conveyor belt.

The inability of people to explain this clearly causes tremendous confusion and leads me to believe that they're simply parroting information they don't understand.

Not saying this is applicable to you but...

If you allow the plane to move relative to the ground, what's the point of the experiment? You're simply exchanging wheels - I understand the wheels have nothing to do with take-off but they do have something to do with the ability for the plane to move forward.

Simply placing the plane on sticks means the friction from the sticks will merely cause the plane to topple over given the thrust, hence you need a conveyor belt to offset that friction.

There's no difference in using a conveyor belt on wheels as opposed to normally on wheels.

First, here's the video from last night's program...
http://www.youtube.com/watch?v=IbRcg3ji_Pc
There is a car accelerating in unison with the plane.

Second, it's force from the propeller that makes the plane move. Wheels do not apply force in the forward ( thrust) direction; they only reduce friction. Increase friction enough and the plane will be unable to move at all -- that's what wheel brakes do.

The conveyor belt is irrelevant because it applies no force to the aircraft that will either accelerate it or decelerate it.

I'm aware of all that. But still not getting why it would stop an airplane from taking off from a conveyor belt or any other moving surface (like the deck of an aircraft carrier in WWII). Let's say our WWII fighter needs to hit 40mph to take off. If the aircraft carrier (and by extension the deck) is moving 40mph SW, and the airplane is moving 40 mph NE, why would the airplane fail to take off, given good weather conditions and a sound plane?

The case of an aircraft carrier is different than the conveyor belt. On the carrier, you are creating a relative wind that is opposite to the aircraft's intended motion. The aircraft can't make the required airspeed for takeoff because the wind subtracts from the aircraft's velocity.

The conveyor belt does none of that. It actually does nothing.

I get this and, now I really think about it, there's no way to keep the plane not moving relative to the ground on a conveyor belt aside from tying a rope to the plane, attaching that rope to a wall or vehicle that matches power and negating the thrust, which makes the entire thing pointless.

I see that the conveyor belt makes no difference at all - it's really about misunderstanding the question. To even think there's a way of keeping the plane stationary relative to the ground is nonsensical.

My idiocy, I guess, is making that consideration.

so the plane had a groundspeed of ZERO and took off?

No, the plane's groundspeed was the same as if the runway was stationary.

The case of an aircraft carrier is different than the conveyor belt. On the carrier, you are creating a relative wind that is opposite to the aircraft's intended motion. The aircraft can't make the required airspeed for takeoff because the wind subtracts from the aircraft's velocity.

The conveyor belt does none of that. It actually does nothing.

I really do suck at analogies, especially lately, it seems. :(