will be answered on January 30th

http://dsc.discovery.com/vi...4&titleId=1344511100

What scares me in the pre vid is the pilot who says his plane will not take off. With such a flawed concept of the function of an aircraft, how did he get his ticket.

Gene

quote Originally posted by scrabblegod: What scares me in the pre vid is the pilot who says his plane will not take off. With such a flawed concept of the function of an aircraft, how did he get his ticket. Gene

MY LORD, he's alive!

------------------
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.

It has already been answered!! Many many times!! It will fly!! Hahahaha!!!
The formula:
Given the same wind resistance/lift factor in when the plane takes off on a normal runway , and from the belt runway, the only difference between them both will be the difference in drag from the wheels spinning normally, and spinning faster to accomodate the rearward movement of the conveyor belt.Once the wheels have actually started to turn (inertia to initial movement is the greatest drag), then the difference in drag on the wheels between the two scenarios will be virtually the same difference in the length of runway needed to enable the plane to take off. (I'm bored !!) So, if the drag differential is an average of say 3% more, then the length of runway needed to compensate will be equally, 3% longer.,to be able to reach the required take-off speed. ...or is that thrust power
Bye!!
Nick

[This message has been edited by fierofetish (edited 12-22-2007).]

I must have missed something in the first thread on this. What exactly, with all the details, is the description of what they are trying to do ? If I understood the original thread, they were supposed to make the plane fly by just spinning its wheels on a treadmill......

https://www.fiero.nl/forum/A...060811-6-038175.html
There ya go, Roger!!
Nick

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction).
The question is:

Will the plane take off or not?


***

Ok as this reads, as they attempt to move the plane forward, the belt moves in the opposite direction keeping the plane in the same position relative to the surrounding air/ objects. Correct ?

If that is the case, I stand as before, theres no way the plane can fly since there is no forward movement of the plane thru the air to give it lift, no matter how fast the plane or conveyor are going. Thats like tieing a rope on the tail and trying to take off, no matter what you do with power, tires or anything else, it aint gonna fly unless you have a 60 mph wind or fan blowing over the wings. If anyone says it will fly, there has to be some other factor(s) thrown in that is not shown above.

Yep!! We have all assumed that the engine/propellers/jet are functioning correctly..and therefore generating thrust against the surrounding air, That is how planes fly..not wheel power against the ground, but thrust against the surrounding air If the engines aren´t running. it can´t move..and so neither will the conveyor belt The point in question should be...is it a glider, or powered aircraft?
Nick

You know they are going to get complains about this one too. Someone will ask why they didn't tie the plane's tail to a fixed point to make sure it didn't move foward.

quote Originally posted by rogergarrison: Ok as this reads, as they attempt to move the plane forward, the belt moves in the opposite direction keeping the plane in the same position relative to the surrounding air/ objects. Correct ? If that is the case, I stand as before, theres no way the plane can fly since there is no forward movement of the plane thru the air to give it lift, no matter how fast the plane or conveyor are going. Thats like tieing a rope on the tail and trying to take off, no matter what you do with power, tires or anything else, it aint gonna fly unless you have a 60 mph wind or fan blowing over the wings. If anyone says it will fly, there has to be some other factor(s) thrown in that is not shown above.

Except the plane won't stay in position, it will move forward regardless of the belt. If the plane was Wheel driven then sure, it would stay in place. But the propulsion system is in no way dependent on the wheels. As soon as the engines are on, the plane will move forward. The wheels themselves will have some resistance, since you'll be spinning them at twice their normal speed.

Alternately, if you took a car and blew wind at it to match its speed, would it stay in place?

[This message has been edited by Xanth (edited 12-22-2007).]

quote Originally posted by rogergarrison: A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). The question is: Will the plane take off or not? *** Ok as this reads, as they attempt to move the plane forward, the belt moves in the opposite direction keeping the plane in the same position relative to the surrounding air/ objects. Correct ?

No.

For the 1000th time, that is not correct.

There is nothing stated in the above scenario which suggests the plane will remain stationary.

quote Originally posted by rogergarrison: Ok as this reads, as they attempt to move the plane forward, the belt moves in the opposite direction keeping the plane in the same position relative to the surrounding air/ objects. Correct ? If that is the case, I stand as before, theres

That is the logical error. Nothing in the original question says the play stays stationary - only that the conveyor speed is equal and opposite of the plane's speed. You make the assumption that will cancel out the plane's forward motion - like it would in a car - and keep the plane stationary.

But, the plane is not propelled by the wheels. The plane's engine pushes against the air and moves the plane forward, regardless of the speed of the conveyor.

In simplest terms, the plane's speed is the airspeed and the conveyor's speed relative to the plane's is the ground speed. As a pilot, you know it's airspeed, not ground speed that matters in a takeoff.

If the plane's moving forward at 100 mph, the conveyor is moving backward at 100 mph. The landing gear are spinning at 200 mph. 100 mph air speed. 200 mph ground speed (relative to the conveyor).

Edit: Oh dammit, Forumula88, you beat me to it. That'll teach me to double check my post to make sure I don't sound like an idiot Oh well, here it is anyway:

No, it won't fly. There's a lot of complicated arguments that I've heard, but basically most planes won't be doing anything and I'll tell you why...

Why is there an instrument in the cockpit that reads "Indicated Air Speed"? Because this is the only way of generating lift on (most) any plane. All that matters is the flow of air over the wings. If there's not enough air moving to create lift, the plane will NOT be flying. Period. Okay?

Granted, the prop may move a bit of air over the wings, but it won't be generating any significant lift, at least not compared to what it takes to actually lift the plane. The only reason planes move forward at all in the first place is to create air speed over the wings. If the plane is pretty much sitting still compared to the air, what's going to make it move UP. What UPWARD force is there? Again, no IAS, no lift.

Put it in a wind tunnel on a treadmill and it will work... but that's different.

As for why it's indicated air speed and not just "speed", the lift is generated by amount of air mass moving over the wings, not just the true speed of the plane relative to the air. Think of it this way, as the air gets thinner and thinner, it loses its ability to have any force whatsoever until the point where there is no air at all, and no force... like space. Less drag, less resistance, but also less generation of lift. You could say that the formula comes down to something like "mass of air per second" (not to be confused with volume).

Of course this is assuming the the conveyor belt is keeping the plane from moving forward at all and that there's no wind tunnel, etc.

[This message has been edited by FieroGT42 (edited 12-22-2007).]

Aaaargh, but the plane will be moving!

Regardless of the treadmill speed the plane will physically move forward, it will not be sitting still. That's the catch, the treadmill will move directly opposite the direction of the plane, but the plane really won't give a darn.

Edit: How many threads do we have about this one subject now? There should be another Plane Vs Treadmill forum

[This message has been edited by Xanth (edited 12-22-2007).]

quote Originally posted by FieroGT42: Of course this is assuming the the conveyor belt is keeping the plane from moving forward at all and that there's no wind tunnel, etc.

HOW does the conveyor keep the plane from moving? I see people making this assumption, but no one can explain how. That assumption is the error.

If the conveyor cannot keep the plane from moving, then the plane takes off.
So explain how the conveyor keeps the plane from moving.

(keep in mind real world examples, like an air craft carrier. The plane can move under it's own power on the deck of the carrier regardless of how fast the carrier is moving.)

[This message has been edited by Formula88 (edited 12-22-2007).]

But Xanth, we have to figure out whether there is an assumption that the treadmill keeps the plane from moving forward. The treadmill could indeed keep the plane from moving due to the combined friction of the suspension system... tires, bearings, brake pads, etc. We'll have to decide on that first. Then, if the plane can overcome the treadmill and start accelerating forward, yes it would then be creating air flow over the wings. Otherwise it's only what the prop is pushing.

I have to say that it's unlikely that a treadmill or conveyor belt will be moving fast enough to keep the plane from moving up to the point where the plane's wheel bearings or tires fail before the treadmill does.... but it's still possible theoretically. The treadmill can exert a rearward force on the plane roughly equal to the total drag in the plane's complete suspension system.

[This message has been edited by FieroGT42 (edited 12-22-2007).]

quote Originally posted by FieroGT42: But Xanth, we have to figure out whether there is an assumption that the treadmill keeps the plane from moving forward. The treadmill could indeed keep the plane from moving due to the combined friction of the suspension system... tires, bearings, brake pads, etc. We'll have to decide on that first. Then, if the plane can overcome the treadmill and start accelerating forward, yes it would then be creating air flow over the wings. Otherwise it's only what the prop is pushing.

Can we assume we would use a normal flight worthy aircraft with wheels for landing gear? (no pontoons or skis, etc.)

Given that, if "The treadmill could indeed keep the plane from moving due to the combined friction of the suspension system... tires, bearings, brake pads, etc." could keep the plane from moving then when that aircraft tried to land on a flat, motionless piece of asphalt - it would crash instantly to zero mph as soon as the wheels touched ground.

HOW does a plane move on the ground? Forget flight, but how does it taxi?
It uses the engine. Well, the engine isn't connected to the wheels - so the engine must be providing thrust somehow. That thrust has nothing to do with the airspeed over the wings - we're not airborne yet.

quote Originally posted by FieroGT42: I have to say that it's unlikely that a treadmill or conveyor belt will be moving fast enough to keep the plane from moving up to the point where the plane's wheel bearings or tires fail before the treadmill does.... but it's still possible theoretically. The treadmill can exert a rearward force on the plane roughly equal to the total drag in the plane's complete suspension system.

That's not part of the original question. Could the treadmill go 10,000 mph backwards and cause the wheels and tires to fail? Does it matter when the question says the treadmill is moving at the same speed as the plane - only backwards.

"The treadmill can exert a rearward force on the plane roughly equal to the total drag in the plane's complete suspension system."

You may have a glimmer of hope in that statement. Is the total drag in the plane's complete suspension system more or less than the output capacity of the plane's engine? That should be a simple question. If the plane's engine puts out less power than the drag - no aircraft will ever fly. If it puts out more, it overcomes the friction, rendering the speed of the treadmill irrelevant with regard to the plane's ability to take off.

[This message has been edited by Formula88 (edited 12-22-2007).]

If the myth is making the assumption that the treadmill will actually stop the plane, then the whole thing is a waste. They'd be asking a question on physics that totally disregards an important physical aspect.

It is possible that the origins of this myth were based on an assumption of the treadmill stopping the plane, or the treadmill is just a simplification of the idea. I would hope that's not the case though.

In that respect I agree with you, if the treadmill did actually stop the plane, it wouldn't fly for the reasons you stated. In a real world scenario, the treadmill would fail to stop the plane assuming it is moving at the same speed in the opposite direction.

Unless you could cheat and crank the treadmill up to the point it burns out the wheel bearings before the plane gets to speed.

quote Originally posted by FieroGT42: But Xanth, we have to figure out whether there is an assumption that the treadmill keeps the plane from moving forward. The treadmill could indeed keep the plane from moving due to the combined friction of the suspension system... tires, bearings, brake pads, etc. We'll have to decide on that first. Then, if the plane can overcome the treadmill and start accelerating forward, yes it would then be creating air flow over the wings. Otherwise it's only what the prop is pushing. I have to say that it's unlikely that a treadmill or conveyor belt will be moving fast enough to keep the plane from moving up to the point where the plane's wheel bearings or tires fail before the treadmill does.... but it's still possible theoretically. The treadmill can exert a rearward force on the plane roughly equal to the total drag in the plane's complete suspension system.

[This message has been edited by Xanth (edited 12-22-2007).]

quote Originally posted by Xanth: If the myth is making the assumption that the treadmill will actually stop the plane, then the whole thing is a waste. They'd be asking a question on physics that totally disregards an important physical aspect. It is possible that the origins of this myth were based on an assumption of the treadmill stopping the plane, or the treadmill is just a simplification of the idea. I would hope that's not the case though. In that respect I agree with you, if the treadmill did actually stop the plane, it wouldn't fly for the reasons you stated. In a real world scenario, the treadmill would fail to stop the plane assuming it is moving at the same speed in the opposite direction. Unless you could cheat and crank the treadmill up to the point it burns out the wheel bearings before the plane gets to speed.

That assumption is the purpose of the question. To show why in physics and engineering when you make certain assumptions, you can totally invalidate any actual engineering data.

You can see how valid the question is when so many people can't see past the assumption they make that the treadmill can stop the plane. The question makes no mention of it - the reader draws that conclusion on their own.

I was in the no fly possition but think i figured out why it will fly. The wheels are free to spin at any speed as it is not wheel driven. Therefore lets say the conveyor moves at speed X. The wheels on the aircraft can freely move at X x 2 and lift off. The engine has thrust and pulls at the air not against the conveyor. It will move forward and gain lift. BTW that plane they are using can takeoff at very low speeds. I flew a Piper PA12 super cruiser in high school and that thing would fly at very low speeds. And with my skinny butt in it I could fly most of the runway in ground effect with the engine throttled all the way back. Had one time where the winds picked up and it wouldn't land the first time at all. Had to go around. Pretty scary being in a plane that won't land.

The original question states the treadmill will run at the same speed the engine is pulling it so the plane WOULD remain stationary. Stationary means no air is flowing over the wings to generate lift....

If it did, why dont all planes takeoff opposite to earth rotation of what....1000 mph hour. Anything doing that should be catapulted into the air whether it was flyable or not. Since im not flying across the yard the idea dont work. The earth surface would be in fact be the treadmill.

It wont fly.... It will set there in the same place relative to the surrounding area till it runs out of gas and goes flying backward off the treadmill. One or the other....the plane or the air HAS to move at sufficient speed to lift it. Wings have to support it in the air, so if its on the treadmill, having the wings or removing them will have no effect on what the plane does. So if you think it would fly, it would be doing it without the wings which would be an impossibilty.

Think of an auto dynomometer. Disregarding safety issues like tiedowns, if you powered the wheels at 100 mph and the drums were rotating opposite at a matching speed...what happens ? Ya, the car will sit there and not move an inch. And if you held you hand out the window, would a 100 mph wind hit it....no. It would be calm because its standing still.

quote Originally posted by rogergarrison: The original question states the treadmill will run at the same speed the engine is pulling it so the plane WOULD remain stationary.

Oh good gawd, this is hopeless...

quote Originally posted by rogergarrison: Think of an auto dynomometer. Disregarding safety issues like tiedowns, if you powered the wheels at 100 mph and the drums were rotating opposite at a matching speed...what happens ? Ya, the car will sit there and not move an inch. And if you held you hand out the window, would a 100 mph wind hit it....no. It would be calm because its standing still.

How about in these scenarios:

Take a wind that moves directly opposing to and equal in speed to the desired movement of the vehicle, the ground being stationary

• With a car, If you give it enough power to go 50mph will the car remain stationary?
  
  
• Now take a plane. If you power it to go 50mph will it remain stationary?
  

Now, the air is totally still and a conveyor belt is moving directly opposing to and equal in speed to the desired movement of the vehicle

• Put the car on the conveyor belt and run the car at 50mph, will it remain stationary?
  
  
• Put the plane on the conveyor belt and set it to run 50mph, will it remain stationary?
  

[This message has been edited by Xanth (edited 12-22-2007).]

Can you imagine the hurtles one must've endured hundreds of years ago trying to prove that the world was round instead of flat? I bet it was almost as difficult as trying to convince SOME people that the plane will fly in this scenario.

Inane laughter resounds around the Forum!! AGGHHHH hahahahahah!! Give it up, Patrick!!! MWUAHAHAHAHHHAHAHA!!! Lost cause!! Yummy yummy yummy I got love in my tummy...BAH!!! IT WILL FLY!!! BET YOU MY FIERO!!(Not including shipping
Nick

Know what would be pretty funny though? Is if they did the experiment and the plane didn't fly

Or if they went and tied it down to keep it from moving, defeating the whole point

In reference to my above post, I'm hoping to demonstrate the difference the mode of propulsion makes. Obviously a car will move forward even with a wind blowing back on it, since its driven by wheels. Equally, the plane will move forward on the belt because its driven by wind (jet, prop, turboprop, etc.)

[This message has been edited by Xanth (edited 12-22-2007).]

quote Originally posted by rogergarrison: Think of an auto dynomometer. Disregarding safety issues like tiedowns, if you powered the wheels at 100 mph and the drums were rotating opposite at a matching speed...what happens ? Ya, the car will sit there and not move an inch. And if you held you hand out the window, would a 100 mph wind hit it....no. It would be calm because its standing still.

But a plane doesn't drive through the wheels! Yes, a car would remain stationary. But not a plane.

A car's engine delivers power to the ground through the wheels.
A plane's engine delivers power how? There's no driveshaft connecting it to the wheels.

quote Originally posted by rogergarrison: The original question states the treadmill will run at the same speed the engine is pulling it so the plane WOULD remain stationary. Stationary means no air is flowing over the wings to generate lift.... Think of an auto dynomometer. Disregarding safety issues like tiedowns, if you powered the wheels at 100 mph and the drums were rotating opposite at a matching speed...what happens ? Ya, the car will sit there and not move an inch. And if you held you hand out the window, would a 100 mph wind hit it....no. It would be calm because its standing still.

But the plane would not be stationary because the plane theory can not be equated to a dynomometer. The wheels of the plane have absolutely nothing to do with movement of the plane.

Maybe this will help (or maybe not....)

There is an airboat (the plane) pointed upstream in a river ( the conveyor belt). Without the engine/prop turning the airboat (plane) will flow with the river (conveyor) at the speed of the river. Now this will be simplified (no friction, no wind, etc.) somewhat but....The airboat driver (pilot) turns on the engine/prop and begins to throttle up the engine. Once the speed of the air flowing out from the prop exceeds the speed of the river, the airboat WILL begin to move upstream. If the river is flowing at 15 mph and the airflow from the prop is 30mph, theorectically the airboat (plane) will move UPSTREAM at 15mph. The river (conveyor belt) is still acting against the bottom of the airboat (plane wheels) but can not prevent the boat (plane) from moving upstream. As the speed of the river (conveyor) increases it will mearly be flowing (spinning the plane wheels) faster along the bottom of the airboat, but effectively doing nothing to slow the airboats (plane) increasingly faster forward (upstream) movement. So, now the airboat engine /prop is pushing the air out at 100mph and the airboat is moving upstream at 85mph.......if the airboat had wings, would it fly?


Edit: Just had another thought.......think about a hovercraft.....would it move forward if the surface below it was moving in the opposite direction? Of course it would because the surface has nothing to do with its ability to move forward. It's the same principle with the plane (except the plane happens to have free-spinning wheels touching the moving surface).

[This message has been edited by turbotoad (edited 12-22-2007).]

The only answer we are getting from this question is what a sad sad state the populace is in.

[This message has been edited by Red88FF (edited 12-22-2007).]

My freakin' head hurts. Are you people still arguing about this?
Well, at least it keeps MythBusters in business I suppose. It's mind boggling to me that the pilot on the show just said that. Cracker Jack box anyone?

Formula88, I give you props for your persistence, but I fear your wheels are just spinning and you'll never take off.

That second video is excellent

Funny I didn't see a propeller on either of those toy planes in the videos.

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

http://www.youtube.com/TheStickman

quote Originally posted by The_Stickman2: Funny I didn't see a propeller on either of those toy planes in the videos.

Then get your own bloody plane and treadmill and do it yourself.

quote Originally posted by rogergarrison: The original question states the treadmill will run at the same speed the engine is pulling it so the plane WOULD remain stationary. Stationary means no air is flowing over the wings to generate lift.... If it did, why dont all planes takeoff opposite to earth rotation of what....1000 mph hour. Anything doing that should be catapulted into the air whether it was flyable or not. Since im not flying across the yard the idea dont work. The earth surface would be in fact be the treadmill. It wont fly.... It will set there in the same place relative to the surrounding area till it runs out of gas and goes flying backward off the treadmill. One or the other....the plane or the air HAS to move at sufficient speed to lift it. Wings have to support it in the air, so if its on the treadmill, having the wings or removing them will have no effect on what the plane does. So if you think it would fly, it would be doing it without the wings which would be an impossibilty. Think of an auto dynomometer. Disregarding safety issues like tiedowns, if you powered the wheels at 100 mph and the drums were rotating opposite at a matching speed...what happens ? Ya, the car will sit there and not move an inch. And if you held you hand out the window, would a 100 mph wind hit it....no. It would be calm because its standing still.

Think about it, you know better.
What's holding the plane back? Is it tied down? Who cares how fast the wheels are spinning? You know that ground speed has nothing to do with flight. Ever take off in a high head wind condition? I know that you've notice how much shorter the take off distance is relative to a no wind or down wind take off. The conveyor is simply a factor thrown in to make folks think about another issue. The conveyor has absolutely nothing to do with whether or not the aircraft can or will fly.

------------------
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.

quote Originally posted by The_Stickman2: Funny I didn't see a propeller on either of those toy planes in the videos.

I think fist two may use small propellers in the rear, like this model: http://www.rctoys.com/rc-pr...S-MINI-CX-FLYER.html

I don't think they'd show up in the vid.

January 30th can't come soon enough.

Here we are!! A VERY simple way to prove things!!

Put the plane on the conveyor belt. Tie a rope to the front of it, fixed to something immovable beyond the end of the conveyor belt. Start the conveyor belt, and run it as FAST as you like!! The plane will stand still, with its wheels rolling on the conveyor belt. The energy or strain placed upon the rope will ONLY BE equivalent to ,not greater than the drag coefficient of the wheels on the aeroplane`s suspension, once the wheels start to turn. Now, start to reel in the rope on a capstan.The plane will move forwrad, against the direction of the conveyor belt. If it were physically possible to reel in the rope as fast as the conveyor belt is turning,(or equal to the power of the engine available) the plane would be pulled forward fast enough for the aerodynamics of the wings to enable the plane to take off.
Some are already getting ready to type 'The rope is fixed to the ground, that isn't the same'...oh, but it is!!! The rope is a direct substitute for the plane's engine, which exerts a force against a medium virtually as static as the ground. The air around the plane, which is unaffected by the conveyor belt.By reeling in the rope, you would be exerting an exact replica of the force of an engine..giving forward momentum. One force of momentum is exerted against the static medium of the ground, the other against the static medium of air, or atmosphere.
The force required to be exerted through the rope against the plane 's drag would be virtually the same as the force required of the engine and propellers or jet. irrespective of whether you speed the conveyor belt to 600mph, the small amount of extra drag on the wheels would still be tiny..and the engine would win!!! ZE PLANE VILL FLY!!
QED
Nick

[This message has been edited by fierofetish (edited 12-23-2007).]

quote Originally posted by blackrams: You know that ground speed has nothing to do with flight. Ever take off in a high head wind condition? I know that you've notice how much shorter the take off distance is relative to a no wind or down wind take off.

The thing is you still need to move the plane to get airflow over the wings. The prop plane is cheating because it's causing airflow.

http://en.wikipedia.org/wiki/Takeoff

quote The speeds needed for takeoff are relative to the motion of the air (indicated airspeed). A headwind will reduce the ground speed needed for takeoff, as there is a greater flow of air over the wings. Typical takeoff air speeds for jetliners are in the 130–155 knot range (150–180 mph, 250–290 km/h). Light aircraft, such as a Cessna 150, take off at around 55 knots (63 mph, 100 km/h). Ultralights have even lower takeoff speeds. The takeoff speed is directly proportional to the aircraft weight; the heavier the weight, the greater the speed needed[citation needed]. Some aircraft specifically designed for short takeoff and landing can take off at speeds below 40 knots (74 km/h), and can even become airborne from a standing start when pointed into a sufficiently strong wind.

If the plane is effectively stationary, even if the engines are full throttle, the only wind flow over the wings are not enough to give it lift.