Who's ready for the new mythbusters?

[Direwolf]

What the hell. How many times do i have to explain it. THERE IS. It takes off normally. Watching the video should have been proof that it WILL take off. How the hell do you see it otherwise?

The problem is that the video isn't really explicit about what in the heck its try to prove. First time I watched I couldn't think of anything it could be about other than the idea that if a plane rolled fast enough on a conveyor it would take off, but thats silly. Only after I read a description and rewatched the important bit did it makes sense.

As for Mythbusters being non-scientific, they mostly practice the down and dirty method of testing something as practically as possible, with as few of the variables as possible. Most of the criticisms I see of the show are usually misunderstandings about what exactly they are testing. With Tesla's device, they had a few basic goals: to see if the principle of the device worked, to attempt to construct one themselves, and to try and create an ideal situation just in case. Since the principle was simply that properly tuned small vibrations could shake large structures, their crude scale test could have been expected to shudder at least a little.

But just in case there was some special property of large metal structures that helps the effect, they brought it out to a bridge and used a device that was more effective than anything Tesla could have made. Surprisingly this test made them re-evaluate the small scale findings, but there wasn't any proof you could actually tear a structure apart with it.

And the final boilerplate for any other criticisms: sometimes they legitimately get it wrong, then get angry mail about it, and then go back and try it again. And to boot they usually test this stuff much more than is seen on the shower (see the clips on the website).

 

[Krynn72]

I love watching mythbusters in my shower.

 

[Ridge]

 

[Vegeta897]

RABLBALN LIENOVNXCLI NSD

Yeah.

Mythbusters can be fun to watch but it's pseudoscience, really. A proper scientific method doesn't a good tv show make, they do shit to get ratings, period.

 

[giant384]

Yeah.

Mythbusters can be fun to watch but it's pseudoscience, really. A proper scientific method doesn't a good tv show make, they do shit to get ratings, period.

bill nye

 

[Dan]

1.there weren't any specific plans on how to make it
2.doing it inside a building is highly dangerous and the myth was wanting a tall building.
3.it doesn't matter what material you use. as long as you find the resonant frequency then it can do what the myth says it will do. in this case no

Edit: Kyrnn a video on youtube really doesnt prove anything to me. if i know the mythbusters, then i know they will use a real plane and some way to have a large conveyor belt. if it takes off then that proves it for good. a toy plane just doesn't do justice for me.

It also depends on the type of steel. Typical steels 100 years ago were much more brittle than today because of sulpher contamination. It also depends on any dampening factors, like air resistance and heat production. Tesla did leave plans for a pneumatic oscillator, they were just to cheap and lazy to follow them.

 

[99.vikram]

1. Conveyor belt will run opposite to the direction of the plane's propulsion.

2. Conveyor belts move the wheels.

3. Wheels aren't attached to plane.

4. Propulsion system works as usual.

5. Plane will still move forward and take off. It will be slower due to friction at the wheels.

Is there anything more to this "debate"?

 

[Ridge]

Yes, the idea is that the treadmill runs at the same pace as the plane, but going the opposite direction...this results in 0 movement.

 

[Krynn72]

Yes, the idea is that the treadmill runs at the same pace as the plane, but going the opposite direction...this results in 0 movement.

The treadmill cannot slow down the plane beyond a slight amount of friction on the tires, IT WILL MOVE FORWARD AND TAKE OFF.

It cannot be explained any simpler than it already has. If you still dont get it, then you're simply refusing to put any thought into it.

 

[xcellerate]

Yes, the idea is that the treadmill runs at the same pace as the plane, but going the opposite direction...this results in 0 movement.

seriously, if you're saying spinning the wheels backwards exerts enough force to hold a plane back from it's 200,000lbs of thrust then you need to reevaluate what you think you know.

 

[Ridge]

At some point as thrust increases and the treadmill speed increases opposite, the wheel bearings WILL burn up at which point the wheels will cease to rotate, pulling the plane backwards...

 

[Direwolf]

Yeah, eventually that will happen at some speed, but remember that those wheels are already rated for the plane to take off and land on, which is pretty fast. They can probably take some abuse before failing.

Edit: And I believe they actually mentioned/showed the plans for Tesla's original device. They then set about trying to construct one, but since all Tesla's device was is a machine that vibrated regularly and could be adjusted, they tried just adapting something else for the job. This proved to be not quite right, but Tesla himself seemed aware that even his original device was not ideal. He theorized that one of the best ways to create such a machine would be with some kind of linear magnetic motor, but nothing good enough along those lines existed at the time. However, the Mythbusters (specifically Grant) happened to have EXACTLY that type of device around, so that is what they tested on the bridge. It's reliability, uniformness of motion, and resolution of tuning all far exceeded Tesla's original design.

 

[xcellerate]

At some point as thrust increases and the treadmill speed increases opposite, the wheel bearings WILL burn up at which point the wheels will cease to rotate, pulling the plane backwards...

.........................or maybe the fuel runs out, or maybe the pilot has a heart attack, or maybe the conveyor belt was built by a Chinese manufacturer and it's bearings seize up before the swiss made bearings on the plane, or maybe 2036 rolls around and the asteroid hits earth.....

I guarantee you those bearings are designed to undergo more stress than the 30 seconds at whatever rpm it would take to lift off. I mean the entire landing gear is designed to safely land a VERY expensive aircraft and 300 people hundreds of times.

 

[Qonfused]

Hey guys, .999 = 1.

 

[Krynn72]

No **** You.

 

[xcellerate]

It won't take off.

If it does take off, I'm going to write "I DO NOT UNDERSTAND PHYSICS" in giant black permanent marker on my forehead.

Seriously.

[edit] Pics will be taken.

Quoted, just cause I really want to hold you to this. :afro:


edit: Turns out their using a REAL plane!! Awesome!!

 

[Viperidae]

It'll only take off if it's on a Technics.

 

[Dan]

.........................or maybe the fuel runs out, or maybe the pilot has a heart attack, or maybe the conveyor belt was built by a Chinese manufacturer and it's bearings seize up before the swiss made bearings on the plane, or maybe 2036 rolls around and the asteroid hits earth.....

I guarantee you those bearings are designed to undergo more stress than the 30 seconds at whatever rpm it would take to lift off. I mean the entire landing gear is designed to safely land a VERY expensive aircraft and 300 people hundreds of times.

Wheel speed no matter what is always low rpm compared to industrial applications, unless you had like 1 inch tires on a jumbo jet there is simply no reason for them to spin very fast at all. You can easily quadruple the speed of your car or plane and it won't wear out the bearings much faster.

 

[Vegeta897]

Wheel speed no matter what is always low rpm compared to industrial applications, unless you had like 1 inch tires on a jumbo jet there is simply no reason for them to spin very fast at all. You can easily quadruple the speed of your car or plane and it won't wear out the bearings much faster.

Umm... point proven?

 

[MiccyNarc]

It will take off. Can't wait to see this FINALLY ****ING PROVEN.

I hate people with no understanding of airplane physics.

 

[Dan]

Umm... point proven?

yeah, I was concurring

 

[Vegeta897]

It will take off. Can't wait to see this FINALLY ****ING PROVEN.

I can't wait to see MythBusters **** it up and then conclude it won't take off.

 

[Ridge]

I wonder if an RC plane will be satisfactory...Ive seen RC helis hover on its tail, upside down, etc...

 

[_Z_Ryuken]

Um, they announced this test on the show, like 2 or 3 weeks ago. Is it airing soon?

They are going to use a truck to pull that long tarp/cloth thing to simulate the conveyor..
I think the biggest problem they thought they might face is overcoming the inertia of the cloth..

 

[xcellerate]

Um, they announced this test on the show, like 2 or 3 weeks ago. Is it airing soon?

tomorrow!

 

[The Monkey]

I highlighted your problems.

It is very different from the car experiment, because the car is propelled forward by its wheels. The reason why the plane DOES NOT stay stationary on the conveyor is that the wheels on a plane are FREE SPINNING. They can spin at any speed. So when the conveyor belt starts going, and the plane starts moving to overcome the friction that would push the plane back, the wheels are spinning at the same speed as the belt is moving. Then once the plane starts picking up the thrust to take off, the plane moves forward on the belt, which means the wheels are spinning at the belt's speed + plane's forward speed. So the plane will go forward and take off because the wheels will simply increase in their RPM to allow forward movement.

Unless the wheels spinning that much cause friction which slows the aircraft down.

 

[Dan]

The problem they will face is creating an accurate feedback loop that can control the speed of the belt. Their truck probably can't match acceleration of the plane. There are actually two problems out there, the problem that the conveyor belt matches the speed of the plane in the opposite direction, and the problem that matches the speed of the wheels in the opposite direction. The 2nd version is a physical paradox where the speeds converge on infinity, so they will have to answer the first question, which everyone knows the answer to already (yes it will take off).

 

[Raziaar]

I can't wait to see MythBusters **** it up and then conclude it won't take off.

That won't happen. Why? Because science is on our side.

And Mythbusters rocks... don't you dare insult it!

 

[giant384]

honestly the only way i see this working is if the conveyor belt stops instantly leaving the wheels spinning at the same speed as they were on the belt then yes. if the plane is stationary and the belt is moving under it then i dont see how that will create lift which ummm kind of makes the plane go up......so by all means explain your airplane physics because the videos of it aren't doing justice. i still believe mythbusters will put it down once and for all though.

 

[Vegeta897]

honestly the only way i see this working is if the conveyor belt stops instantly leaving the wheels spinning at the same speed as they were on the belt then yes. if the plane is stationary and the belt is moving under it then i dont see how that will create lift which ummm kind of makes the plane go up......so by all means explain your airplane physics because the videos of it aren't doing justice. i still believe mythbusters will put it down once and for all though.

This has nothing to do with understanding airplane physics. All you need to know that a plane moving through the air will make it fly.

The thing that gets people confused is that they think the conveyor belt will do anything to stop the plane from moving forward. It will not, just cause the wheels to rotate 2x faster than they normally would.

This thread is the biggest god damn broken record in the world. Go read through the thread before posting, kthx. It's explained a billion times.

 

[_Z_Ryuken]

The problem they will face is creating an accurate feedback loop that can control the speed of the belt. Their truck probably can't match acceleration of the plane. There are actually two problems out there, the problem that the conveyor belt matches the speed of the plane in the opposite direction, and the problem that matches the speed of the wheels in the opposite direction. The 2nd version is a physical paradox where the speeds converge on infinity, so they will have to answer the first question, which everyone knows the answer to already (yes it will take off).

If they wanted to be 100% accurate, yes, but the myth (of it not taking off) will be busted even if the truck is moving too fast. The biggest problem they face is accelerating the truck as there will be enormous friction on that cloth. Supposedly it is fairly slick, but since we know what the outcome should be, if they can get this one part to work it will be good enough maybe not for science but for people like giant384 and stigmata.
I can see this experiment failing if/when: the cloth's inertia proves too much for the truck to overcome or the fasteners tensile limits, or they run out of length.
The good news is, if that happens, they will have to build a giant conveyor. The bad news is, they won't because the plane will not be able to take off due to it plummeting over the end, nose diving into the ground after thrusting itself across.

 

[xcellerate]

This thread is the biggest god damn broken record in the world. Go read through the thread before posting, kthx. It's explained a billion times.

You'd think it would be that easy. Plus 5 seconds on google will give you a dozen physics forums where they discuss and all say the same thing, plus the videos on youtube showing the same thing...but for some reason people still can't agree on an answer.


Honestly, it amazes me. I mean, a similar question is "if you put a rocket car on a conveyor belt, will it move?"

or

"If you put a water plane in a river with the current flowing against the plane, will it take off?"

 

[Vegeta897]

plummeting over the end, nose diving into the ground after thrusting itself across.

And everyone dies, the end.

 

[_Z_Ryuken]

^mlol

"If you put a water plane in a river with the current flowing against the plane, will it take off?"

If the current is choppy enough and moving fast enough it could inhibit take off, but that is an entirely different animal. The water produces much more drag than a good wheel bearing.

Here's an equally vexing question:
Can a plane land on a conveyor moving in the same direction at the same speed as the plane?

 

[giant384]

The treadmill cannot slow down the plane beyond a slight amount of friction on the tires, IT WILL MOVE FORWARD AND TAKE OFF.

It cannot be explained any simpler than it already has. If you still dont get it, then you're simply refusing to put any thought into it.

so far no one has explained how it somehow magically lifts. you have all just said "it will take off"

if the belt is moving at the same pace of the plane then that can only make it stationary. in other words its like you or me just running on a treadmill and going nowhere. sure it has lots of thrust but that doesnt do shit if there is so much resistance from the belt moving and the same speed. also whats with the comment about "wheels arent attached to plane"??

 

[_Z_Ryuken]

The thing you aren't grasping is it's impossible for the belt to match the speed of the plane because the plane is moving under thrust, meaning it's engines are moving air thus pulling the plane. The belt will accelerate infinitely as the wheels spin mercilessly until the plane takes off, if there is enough length to the belt. Try to imagine a treadmil as long as a runway, and not some gym equipment. The plane is in no way bound to the conveyor.

If you were running on a treadmill and had wings you could take a few flaps and be gone. You don't need your legs to fly.

 

[xcellerate]

if the belt is moving at the same pace of the plane then that can only make it stationary.

NO. No it won't.

That's the entire point! Just because the conveyor is moving backwards, does NOT mean that the conveyor is applying enough force to HOLD the plane back when it starts to add more thrust.

The reason the plane moves backwards anyway is because of small amounts of friction within the wheel bearings on the plane. So...once the plane's thrust overcomes that small amount of friction, then all the thrust applied after that point will move the plane forward.

 

[giant384]

NO. No it won't.

That's the entire point! Just because the conveyor is moving backwards, does NOT mean that the conveyor is applying enough force to HOLD the plane back when it starts to add more thrust.

The reason the plane moves backwards anyway is because of small amounts of friction within the wheel bearings on the plane. So...once the plane's thrust overcomes that small amount of friction, then all the thrust applied after that point will move the plane forward.

i think that finally answers it, but im really looking forward to mythbusters doing it.

 

[Dan]

Here's an equally vexing question:
Can a plane land on a conveyor moving in the same direction at the same speed as the plane?

Depends on the length of the runway, and whether you consider landing to be stopped relative to the ground or relative to the earth. The planes wouldn't be able to use wheel breaking to slow down once on the tarmac, but the engines can provide reverse thrust which would allow it to stop.

so far no one has explained how it somehow magically lifts. you have all just said "it will take off"

if the belt is moving at the same pace of the plane then that can only make it stationary. in other words its like you or me just running on a treadmill and going nowhere. sure it has lots of thrust but that doesnt do shit if there is so much resistance from the belt moving and the same speed. also whats with the comment about "wheels arent attached to plane"??

Most people so far have just assumed that it is so obvious as to not require explaining. The key element is that a free spinning wheel can't apply any force in the direction the wheel is pointing. Imagine driving on the highway and sticking a roller blade out the door and touching it to the pavement, it wouldn't rip your arm off because the wheels just spin. The same thing applies to a plane. For an ideal wheel, the treadmill cannot provide any resistance, you can move the treadmill at whatever speed you want and the wheels just spin without transmitting any force. In reality you would get a little bit of bearing friction, but it is still so small compared to the forward thrust that you can ignore it.

 

[giant384]

this is a perfect example to what is expalined above

"Put a pair of rollerblades on and go stand on a running treadmill (you can hold on to the sides if you want). Your feet will move backwards due to some frictional force of the rollerblades' axles, but they won't move backwards at anywhere near the velocity of the treadmill. You'll even find that you can pull yourself forwards with your arms (kind of like an airplane's engine, huh?) Now, take the rollerblades off and stand on the treadmill in bare feet. I guarantee you that you're going to be moving backwards a whole lot more quickly because now the force of the treadmill is acting on your body much more efficiently than it was when you were wearing the rollerblades."

eidt: i honestly believe the confusion is in the wording of the problem and everyone seems to believe a plane works the same as a car.