Neither. It's almost like watching someone try to re-invent the wheel.

Simple physics would tell someone that the rolling resistance produced by the faster speeds of the wheel bearings wouldn't be enough to overcome the thrust generated by the plane's engines. Yet, here we are seven pages later.....

EDIT: Make that eight pages of popcorn eating goodness.

[This message has been edited by Deabionni (edited 01-02-2008).]

quote Originally posted by Deabionni: Neither. It's almost like watching someone try to re-invent the wheel. Simple physics would tell someone that the rolling resistance produced by the faster speeds of the wheel bearings wouldn't be enough to overcome the thrust generated by the plane's engines. Yet, here we are seven pages later..... EDIT: Make that eight pages of popcorn eating goodness.

and - a little more physics for ya: the rolling resistance will not affect the speed needed, just the power needed to attain that speed.
it will still be the same take-off speed - no matter what the rolling resistance is.

plane air speed = a
conveyor negative speed = b
Wheel ground speed = a+b

There is no discernible Resistance. The wheels ground rotation will never exceed twice the wings air speed given a conveyor moving at equal opposite speed. If you change the variable to something other than equal then you could at some extreme figure give consideration to Resistance.

Gokart is just yanking everyones chain by using the exact same misleading direction that the original question intended. In short air and ground don't mix.

Forget the wheels and put the plane on skids. No need to worry about rotating wheels or bearings. Once you overcome the frictional forces the airplane would move and fly.

Reduce it to its finality:
"Can an unstoppable force move and unmovable object?"
Makes just as much d_&n sense if you want to argue
about irrationals.
Sheeesh........

quote Originally posted by TennT: "Can an unstoppable force move an unmovable object?"

I believe that would be the beginning of anti-matter, and even trying to create such a scenario could possibly destroy all life on earth and earth itself!

....Better off to just leave that one alone....

[This message has been edited by Deabionni (edited 01-02-2008).]

quote Originally posted by TennT: Reduce it to its finality: "Can an unstoppable force move and unmovable object?" Makes just as much d_&n sense if you want to argue about irrationals. Sheeesh........

or, could god make a boob so big that even he couldn't lift it?

quote Originally posted by TennT: "Can an unstoppable force move an unmovable object?"

That riddle was solved when Chuck Norris punched himself in the face. There were no survivors.

------------------
"Semper Fiero"

quote Originally posted by Gokart Mozart: The thing is it isn't a quick pull like the pull the tablecloth trick. It's a slow pull to match the speed of the plane. The plane still needs to roll forward and it can't. I've stated before how much runway a plane needs to take off. It doesn't matter how much thrust it has, it still needs to roll forward in relation to the runway - meaning non-moving ground and air. Let me state this again: If the conveyor is still, the normal speed (lets say 120) is required to take off. The distance would be normal. If the conveyor is moving forward at 120, the plane would be able to lift off without any power from the plane. It could take off immediately. If the conveyor is moving backwards at 120, 240 is needed to lift off. The distance would be (basically) normal if the plane goes 240. If the conveyor matches the speed of the plane, it can't take off.

i cant help but think it will still fly its grabing air so i can see it going faster then they could pull the tarp, unless they can match that speed (and i think they are trying to do that) i think the wheels will just freewheel and the plane will take off like normal. but what do i know i dont know how to fly guess we gotta wate and see.

Next question. Will the conveyor belt have to be as long as a regular runway ? Or, for those of you that think it will fly, would you be willing to pilot or ride in one trying to take off from the edge of a twenty story building?

^^^ Just as long as a regular runway, as the conveyor belt would have little to no effect on the plane.

quote Originally posted by cliffw: Next question. Will the conveyor belt have to be as long as a regular runway ? Or, for those of you that think it will fly, would you be willing to pilot or ride in one trying to take off from the edge of a twenty story building?

I would pilot the "airplane on a conveyor belt" from the edge of a twenty story building providing said building covered as much distance as said airplane normally requires to take off. That would be darn fun.


This has been going nowhere for eleventy-billion pages all across the internet now, mostly because people like playing devil's advocate in a very annoying way.

quote Originally posted by cliffw: would you be willing to pilot or ride in one trying to take off from the edge of a twenty story building?

I've actually done that one. But, I was flying a OH 58 Super A at the time.

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

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

...for boasting!! Hahaha!! Been dying to try that out
Will it work?
YES!!
Nick

[This message has been edited by fierofetish (edited 01-04-2008).]

quote Originally posted by fierofetish: [IMG]https://images.fiero.nl/pffimages3/banhim.gif[/IMG ]...for boasting!! Hahaha!! Been dying to try that out Will it work? YES!! Nick

Ahh, No, it didn't work, this time.

Does now, Ron!! ..what the heck does this mean anyway???"......was flying a OH 58 Super A at the time. "...and where, and did you get booked for doing it??
Nick
------------------

Helicopter, Nick, Helicopter.

Ron flies those damn things that won't really fly, they're just so ugly the Earth repels them.

John Stricker

quote Originally posted by fierofetish: Does now, Ron!! ..what the heck does this mean anyway???"......was flying a OH 58 Super A at the time. "...and where, and did you get booked for doing it?? Nick

I did it! I found Gokart's test plane!

------------------
"Semper Fiero"

Got an English sponsor, figures.......

quote Originally posted by cliffw: Next question. Will the conveyor belt have to be as long as a regular runway ? Or, for those of you that think it will fly, would you be willing to pilot or ride in one trying to take off from the edge of a twenty story building?

Actually I bet using the plane mythbusters is using if you rolled it off the side of a 20 story building you could probably fly it before the ground comes up. That plane might fly at only 40-50 mph.

------------------
My sites
http://the-stickman.tripod.com

http://www.youtube.com/TheStickman

quote Originally posted by Formula88: Answer the question. What's going 120 in your example?

Ok... I'll play... and I am not trolling, my poor adled head is trying to grasp the concept which seems quite obvious to everyone else...
But in Gokarts example..., If I read it correctly..., two things are going 120:
1) the plane speed
2) the conveyer speed

So, uhm, how did that prove him wrong?

quote Originally posted by The_Stickman2: Actually I bet using the plane mythbusters is using if you rolled it off the side of a 20 story building you could probably fly it before the ground comes up. That plane might fly at only 40-50 mph.

Probably even a little lower than that. I would guess the stall speed is in the mid to low 30's. A Cessna 152 flies at 48-55mph.

For those who are still like think of it like this: put a hover craft on a treadmill. It will go anywhere you want it too (since it is suppose to be floating theoretically on a frictionless surface of air). The hovercraft moves by moving air with its fan, not by any interaction with the ground. Same as an airplane, only the airplane uses wheels to interact with the ground and not a cusion of air.

quote Originally posted by blakeinspace: Ok... I'll play... and I am not trolling, my poor adled head is trying to grasp the concept which seems quite obvious to everyone else... But in Gokarts example..., If I read it correctly..., two things are going 120: 1) the plane speed 2) the conveyer speed So, uhm, how did that prove him wrong?

If the plane is moving 120MPH, then it's moving forward. The engine is able to overcome whatever small forces the conveyor belt imposes on the plane. The plane moves up to it's normal takeoff speed, and flies.

On a side note, in the example given the plane's wheels are also spinning at twice the speed that the conveyor is moving. The only way for the wheels to spin at twice the conveyor speed, is if the plane were moving forward. If the plane were sitting still, then the wheels would only spin the same speed as the conveyor belt is moving backward. So if the conveyor belt were moving at 120MPH, and the plane was sitting still; then the plane's wheels would only be spinning 120MPH in reverse. (Same speed as the conveyor belt is spinning them).

In short, the plane is moving at 120MPH, hence it is moving forward and will take off.

[This message has been edited by Deabionni (edited 01-04-2008).]

quote Originally posted by blakeinspace: Ok... I'll play... and I am not trolling, my poor adled head is trying to grasp the concept which seems quite obvious to everyone else... But in Gokarts example..., If I read it correctly..., two things are going 120: 1) the plane speed 2) the conveyer speed So, uhm, how did that prove him wrong?

Which is why I asked for clarification. If the plane's speed is 120, then the plane is moving, and therefore it can take off.

He's trying to maintain the plane's speed is 120, yet the plane is not moving, as if to suggest there's a speedometer on the plane reading 120. But WHAT is actually moving at 120? If it's "the plane" then the plane is moving.

quote Originally posted by jstricker: Helicopter, Nick, Helicopter. Ron flies those damn things that won't really fly, they're just so ugly the Earth repels them. John Stricker

Good one! I hadn't heard that one before. The one I knew is "helicopters don't fly, they beat the air into submission."

Hey, Gokart - what makes a helicopter lift off the ground?

quote Originally posted by 86fierofun: For those who are still like think of it like this: put a hover craft on a treadmill. It will go anywhere you want it too (since it is suppose to be floating theoretically on a frictionless surface of air). The hovercraft moves by moving air with its fan, not by any interaction with the ground. Same as an airplane, only the airplane uses wheels to interact with the ground and not a cusion of air.

I tried to bring up the helicopter scenerio (which is virtually the same as your hover craft in this application) months, maybe years ago when the other thread had just started and several folks couldn't relate to how it applied. I was told that it was "different" then so I just dropped it. Didn't have the time or inclination to give classes on how helicopters actually fly. I agree with your scenerio.

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

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

[This message has been edited by blackrams (edited 01-04-2008).]

Leave the cars, treadmills with rope, boats, hovercraft, helicopters, rockets, magnetic lifts, swimmers, telepaths and anything else out. It doesn't apply and makes things tougher for you to see why the plane won't fly.

Once again let me say: torque isn't used here. If you think that, step away from the thread.

For those that are hooked on 120 as a number I threw out, that's all it is. It could be 1 or 20 or 50 or any other number. I thought is was a good number to say for take off speed.

How did the plane get to that speed? Simply said, it didn't. A longer version would be if you're on a normal runway and take the throttles to full throttle to gain speed, after a certain time and distance it would reach that speed. We're using that throttle position to determine speed. If it was at 1/4 throttle, hypothetically the max speed would be 30 mph. Normally windspeed is calucated by the pitot tube. It can't calculate ground speed. Let's just say it has GPS.

The question doesn't say what the windspeed is so let's assume it's 0. The ground of course doesn't move so it's 0.

I'm going to quote things from Wikipedia because it's easy to find without having to list links.

Let's first look at a normal take off.
2:52 it's sitting still.
2:56 it starts to roll.
3:49 it starts to lift.

The Airbus A330-300 has a 478,400lb max take off weight and the engines produce 73,000lb ft thrust. At max weight it needs about 8200 feet to take off.


To be continued....

Once again...

quote Originally posted by AntiKev: ...the plane isn't driven by it's wheels, it's driven by the reaction between the spinning propeller and the air. The conveyer has NO EFFECT on the aircraft.

Read my second sentence.

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A fixed-wing aircraft generates forward thrust when air is pushed in the opposite the direction of flight. This can be done several ways including by the spinning blades of a propeller, or a rotating turbine pushing air out the back of a jet engine, or by ejecting hot gases with a rocket engine. The forward thrust is proportional to the (mass of the air) multiplied by (mean velocity of the airstream).
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Thrust-to-weight ratio is, as its name suggests, the ratio of instantaneous thrust to weight (where weight means weight at the Earth’s surface). It is a dimensionless parameter characteristic of rockets and jet engines, and of vehicles propelled by such engines (typically space launch vehicles and jet aircraft). It is used as a figure of merit for quantitative comparison of engine or vehicle design.
The value is larger for an engine than for a whole launch vehicle; the engine thrust-weight is of use since it determines the maximum acceleration that any vehicle using that engine could theoretically achieve with minimum propellant and structure attached.
For a takeoff using pure thrust and no wings, the thrust-weight ratio for the vehicle has to be more than one (for launch from the Earth's surface, for launch from the Moon it only needs to be more than 0.1654). In general, the thrust-to-weight ratio is numerically equal to the g-force that the vehicle can pull, provided the g-force exceeds local gravity then takeoff can occur.
Many factors affect a thrust-to-weight ratio, and it typically varies slightly over the flight. For valid comparison, thrust should be measured under controlled conditions. The main factors that affect thrust include freestream air temperature, pressure, density, and composition. Depending on the engine or vehicle under consideration, the actual performance will often be affected by progressive fuel consumption (causing a rise in thrust-weight ratio), buoyancy, and local gravitational field strength.
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LAW III: To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts. — Whatever draws or presses another is as much drawn or pressed by that other. If you press a stone with your finger, the finger is also pressed by the stone. If a horse draws a stone tied to a rope, the horse (if I may so say) will be equally drawn back towards the stone: for the distended rope, by the same endeavour to relax or unbend itself, will draw the horse as much towards the stone, as it does the stone towards the horse, and will obstruct the progress of the one as much as it advances that of the other. If a body impinge upon another, and by its force change the motion of the other, that body also (because of the equality of the mutual pressure) will undergo an equal change, in its own motion, toward the contrary part. The changes made by these actions are equal, not in the velocities but in the motions of the bodies; that is to say, if the bodies are not hindered by any other impediments. For, as the motions are equally changed, the changes of the velocities made toward contrary parts are reciprocally proportional to the bodies. This law takes place also in attractions, as will be proved in the next scholium.
--------
In physics, motion means a continuous change in the location of a body. All motion is the result of an applied force. Motion is typically described in terms of velocity, acceleration, displacement, and time.[1] Additionally, once an object is in motion it gains a property called momentum which is related to the object's mass and velocity. Due to the law of conservation of momentum everything in the universe is constantly moving and the natural state of the universe is motion.[2] However, because everything is in motion, true absolute motion cannot be determined, and only motion relative to a point of reference can be determined, this type of motion is known as relative motion.[3]
--------
Inertial mass is a measure of an object's resistance to changing its state of motion when a force is applied. An object with small inertial mass changes its motion more readily, and an object with large inertial mass does so less readily.
--------
Classical mechanics (commonly confused with Newtonian mechanics, which is a subfield thereof) is used for describing the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. It produces very accurate results within these domains, and is one of the oldest and largest subjects in science and technology.


more later...

This is getting out of hand.
Yesterday I heard Neal Bortz talking about this on his radio show. He said it will fly (but then he is a pilot and any pilot should know it will fly) while his engineer on the show says it will not. The engineer then went on to say it may fly on a STOL type aircraft, but would not on a large 747 type aircraft

Repeat after me GOZART
IT WILL FLY IT WILL FLY
IT WILL FLY IT WILL FLY
IT WILL FLY IT WILL FLY
IT WILL FLY IT WILL FLY
IT WILL FLY IT WILL FLY
IT WILL FLY IT WILL FLY

Gene

He may be a pilot but he's a lawyer...

quote Originally posted by Gokart Mozart: He may be a pilot but he's a lawyer...

You have to try and not hold peoples faults against them.

Gene

quote Originally posted by Gokart Mozart: For those that are hooked on 120 as a number I threw out, that's all it is. It could be 1 or 20 or 50 or any other number. I thought is was a good number to say for take off speed.

It's not important that the number you chose is 120. Like you said, that's just a good number for take off speed.

The point is, you said the plane speed was 120, implying the plane speed is something other than zero.

WHAT is that speed referring to? What is moving?

You're still saying the backwards movement of the conveyor cancels out the forward movement of the plane, but you can't explain HOW.

quote Originally posted by Gokart Mozart: Which theory are you talking about? I want to be sure what you're rebutting. air speed 0 plane speed 120 tire speed 240 conveyor speed -120 ground speed 0

How do you figure ground speed = 0, air speed = 0, and yet the "plane speed" is 120.

With no wind, the air speed and ground speed (actual ground, not the conveyor) are equal. If the plane is moving forward at 120, the conveyor is, by design, moving backwards at 120, and therefore the wheels are turning at 240. But the point you keep missing is, if the plane is moving forward at 120 - that means THE PLANE IS MOVING FORWARD.

If the plane is not moving forward, the conveyor will not be running. The plane speed and conveyor speed are always equal and opposite.

So how do you have a "Plane speed" of 120 and an air speed of 0?

quote Originally posted by Deabionni: On a side note, in the example given the plane's wheels are also spinning at twice the speed that the conveyor is moving. The only way for the wheels to spin at twice the conveyor speed, is if the plane were moving forward.

Ok... for some reason... that sentence there helped clarify everything a lot better than the hovercraft and roller skate/shove examples...

Thanks amigo's!

I are smarter now!!

quote Originally posted by Gokart Mozart: Leave the cars, treadmills with rope, boats, hovercraft, helicopters, rockets, magnetic lifts, swimmers, telepaths and anything else out. It doesn't apply and makes things tougher for you to see why the plane won't fly.

It doesn't matter what examples we use to compare with the plane, as all the examples given would be fundamentally the same as a plane on a conveyor belt. For that matter, if you want to leave things out of the equation, try leaving the conveyor belt out; as in the end it doesn't actually make a difference, and makes things tougher for you to see why the plane will fly.

Gokart - how does a helicopter lift off the ground?

I just HAD to round it up to the 100 mark...and not just for fun..didnīt realise I hadnīt given you a plus until now Sorry.. it is a sincere one
Nick

quote Originally posted by blakeinspace: and on a side note... deabbioni... that bump in your head bobbing cheetah bar is from me