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Atl5p
QUOTE (egnorant+Feb 12 2007, 02:03 PM)
So you agree that it also does not state where the belts speed is related to.

If the planes speed is related to the surface of the belt then the plane flies!
Belts speed is relative to the plane as it passes under the plane...correct?

Bruce

The OP does not state where the belt's speed is related to, you are correct.

So, let's relate the belt's speed to the plane.

And the plane's speed related to the belt.

So the belt is moving under the plane at 50mph.

And the plane is moving over the belt at 50mph.

And you say the plane flies?

Uh, I don't think so. Plane has 0 IAS in that situation.

OR, if the plane has 50mph IAS: Beltspeed related to plane is 100mph, and Plane speed related to belt is 100mph. Plane flies.

So, you have shown a version where the plane can do either..."fly" AND "no fly"...

Great work Bruce! Do you have another example of how inconclusive results can be obtained due to the fact that the OP's fatal flaw is the fact that it does not specify 'where' the plane's speed is related to (or the belt for that matter)....

Again, great find Bruce! Excellent.

Now, who else will answer Bruce's challenge???

Once again, the OP does not state 'where' or 'what' to relate the plane or treadbelt's speed to. This (as Bruce has pointed out) can result in disparate results, ie 'answers' which are inconsistant. This is the main reason that a definitave answer cannot be determined for this riddle....the only 'correct' answer is one which clearly defines this speed relation.

Bruce has pointed out another example as to why this question can never be correctly answered without stipulating 'where' the speeds are measured from.

I would encourage others to provide examples which futher show that the OP is flawed in that it does not specify 'where' the speeds are related.

Again, great job Bruce, proving my point! Kudos!
egnorant
So you admit that, by your explaination, it is correct to state that a normal take-off (like you see at the airport everyday) is a valid answer to the original question?

Bruce
physics pro
Ok, the problem with this question is that It has 2 parts some people see the first part some people see the second, however see them together use them with each other and your outcome is the right answer.

Also lets not get all sideways by using pointless examples such as hovercrafts, rocket cars, winged cars and my favourite the match box on the treadmill. Don’t get me wrong they prove there point, but they are that far from the problem its not funny.

The first part - The wheels. Let’s make a few assumptions first,

- The wheels stay connected with the conveyer.
- The conveyer rotates at the same speed as the wheels rotate. (No velocity (speed))
-like in all theoretical physics questions friction isn’t being taken into account, don’t
Fooled. When I say friction I mean forces that work against movement.

Ok let’s say the jet/plane has just started its attempt to accelerate. (If the jet/plane accelerates ‘shows over’ it takes off). The jet/planes wheels are spinning at say… 5m/s/s so the conveyer will speed up to 5m/s/s, therefore 5 – 5 = 0 witch means no extra acceleration in ether way (yet again no velocity). It simply doesn’t move because the ‘magical’ computer connecting the jet/plane with the conveyor is so smart.

The second part- Gravity. Quick physics lesson.

- Gravity is a acceleration not a force or a energy that is why it is measured in m/s/s. (I know that there will be some smart guy that sets out to prove me wrong on this using string theory (string theory is a very advanced physics) but please let’s talk in reality for a moment)
-3rd law of motion, equal and opposite reactions.

Ok with that out of the way. Gravity’s acceleration is 9.8m/s/s down, (these are vector quantity’s not scalar don’t be confused) DOWN is the key word here because for something to achieve ‘flight’ it doesn’t need a aerofoil or a jet engine all it needs to do is accelerate UP at 9.8m/s/s or more. Now the jet/plane exerts force backward to go forward, eg thrust or pushing more air backward. Is the force being pushed down to active an UPward acceleration? NO (F=M.a). The force being created by the thrust is being countered (opposite reaction) by the magical conveyor. (Because we know that the force can’t disappear). By the way jump jets are a different matter.

In closing, the conveyor keeps up with the jet/plane so I can’t go forward.
And it cant go up unless it pushes force down accelerating up.
Without these the plane isn’t going anywhere.

By the way I’m only 16

I would also like to take the time out to say who ever came up with this question is twice as smart as the answer.
Fynlcut
dee dee dee!
rethinker
If your that smart already and you are only 16 you will be even smarter when you rethink your physics and know that the belt and wheels act as 0 and so have little resistance.
This is why they put wheels on planes. (So the plane can move over the surface. It matters not if the surface is stationary or going away behind the wheels.

You will also enjoy reading when you get to be 21 or so.

You have much to look forward to.
Maybe you will get to play with airplanes and trucks.

And take that stupid mask off! If your 16 and hiding behind a mask, why should we believe you?
physics pro
Resistance has nothing to do with it. Or the wheels. It is all to do with the force and where it is going, with out force there is no movement F=M.a.

Should my age matter?

You need to think physically with these questions not logically. And yes there is a difference.

My physics was taught to my by a military physics lecturer. ill ask him this same question tomorrow just for you my friend. peace
egnorant
QUOTE (physics pro+Feb 13 2007, 10:10 AM)

The first part - The wheels. Let’s make a few assumptions first,

- The wheels stay connected with the conveyer.
- The conveyer rotates at the same speed as the wheels rotate. (No velocity (speed))
-like in all theoretical physics questions friction isn’t being taken into account, don’t
Fooled. When I say friction I mean forces that work against movement.

A very closed set of assumptions and basically incorrect.

QUOTE
The conveyer rotates at the same speed as the wheels rotate. (No velocity (speed))

This is the basic pitfall for this question.
Movement and speed of the plane is not always based on wheelspeed.
I can think of many example where a plane can reach takeoff speed with no wheelspeed at all! No skidding or sliding either!

Bruce

TheEnd
QUOTE (physics pro+Feb 13 2007, 12:34 PM)
Resistance has nothing to do with it. Or the wheels. It is all to do with the force and where it is going, with out force there is no movement F=M.a.

Should my age matter?

You need to think physically with these questions not logically. And yes there is a difference.

My physics was taught to my by a military physics lecturer. ill ask him this same question tomorrow just for you my friend. peace

Since you are using force, let use this angle. Please explain how the force of the planes engines are overcome (countered) by the belt when the only contact between the plane and belt is through the planes wheels? IOW: how is the force from the belt transferred to the plane to counter the thrust of the engines if the wheels just spin freely?

Again, A planes speed is never measured by the wheel speed. It is either air-speed or ground-speed! Wheel-speed and ground speed are _usually_ the same while the plane is on the ground, but not always!

TEOTW(AWKI)
Atl5p
QUOTE (egnorant+Feb 12 2007, 02:39 PM)
So you admit that, by your explaination, it is correct to state that a normal take-off (like you see at the airport everyday) is a valid answer to the original question?

Bruce

Bruce,
As I've stated about a billion times:

When IAS is used to determine plane speed, the plane will fly.

When 'wheelspeed'* is used, the plane will not fly.

It all depends on where the speeds are measured from.

If you relate belt speed to plane, and plane speed to belt (as you seem to want), then both of the speeds will ALWAYS equal each other, regaurdless of whether or not the plane has IAS. So that version does both, flies and no flies.

(*wheelspeed means 'the speed at which the plane moves reletive to the surface of the treadbelt.....there does not have to be actual wheels involved, there could be skis or pontoons or everlastinggobstoppers...whatever)

egnorant
QUOTE (Atl5p+Feb 13 2007, 06:19 PM)
Bruce,
As I've stated about a billion times:

When IAS is used to determine plane speed, the plane will fly.

When 'wheelspeed'* is used, the plane will not fly.

It all depends on where the speeds are measured from.

If you relate belt speed to plane, and plane speed to belt (as you seem to want), then both of the speeds will ALWAYS equal each other, regaurdless of whether or not the plane has IAS. So that version does both, flies and no flies.

(*wheelspeed means 'the speed at which the plane moves reletive to the surface of the treadbelt.....there does not have to be actual wheels involved, there could be skis or pontoons or everlastinggobstoppers...whatever)

No it does not!

You have been stating that there is no accepted basis for the point that the speed of the plane is measured against.

I pointed out that , by your explaination, there is also no basis for the point against which the belt is measured against.

I am not proposing a belt speed related to the plane/plane speed related to the belt scenario.

I am proposing that, by your explaination, a plane speed related to the ground/air and belt speed related to the plane.
This would result in the belt not moving relative to the ground/air.
And yes this has the plane flying.....I am looking to see if you believe this to be a valid interpretation.
This is the reiprocal of your plane speed related to the belt and belt speed related to the ground/air.

You have claimed that the plane relative to the belt an belt relative to the ground/air is a valid interpretation.

I am asking if you believe that plane speed relative to the ground/air and belt speed related to the plane is a valid representation of the original question.

Yes or No?

Bruce

Atl5p
QUOTE (egnorant+Feb 13 2007, 02:23 PM)
No it does not!

You have been stating that there is no accepted basis for the point that the speed of the plane is measured against.

I pointed out that , by your explaination, there is also no basis for the point against which the belt is measured against.

I am not proposing a belt speed related to the plane/plane speed related to the belt scenario.

I am proposing that, by your explaination, a plane speed related to the ground/air and belt speed related to the plane.
This would result in the belt not moving relative to the ground/air.
And yes this has the plane flying.....I am looking to see if you believe this to be a valid interpretation.
This is the reiprocal of your plane speed related to the belt and belt speed related to the ground/air.

You have claimed that the plane relative to the belt an belt relative to the ground/air is a valid interpretation.

I am asking if you believe that plane speed relative to the ground/air and belt speed related to the plane is a valid representation of the original question.

Yes or No?

Bruce

At issue is the interpretation, of Bruce:
"Plane speed relative to the ground/air and belt speed related to the plane"

Bruce is asking Atl5p two seperate questions (although I believe Bruce thinks he's asking me just one question....I see two seperate questions)

#1"I am looking to see if you believe this to be a valid interpretation."

#2"I am asking if you believe (the above) is a valid representation of the original question.

Answer to #1: Yes, I believe it is a valid 'interpretation' of the OP. My point is, by the wording of the question alone, a multitude of differing 'interpretations' can exist, limited only by the number of people who read the question, I suppose.

Answer to #2: No, I do not believe it is a valid 'representation' of the question...and by that I mean "In MY OPINION (ATL5P) I don't think that is what the OP was really asking."

In MY OPINION, I think it was asking "Can a treadbelt prevent a plane from taking off"
or
"When the treadbelt matches the plane's wheelspeed (whereby wheelspeed = the speed at which the plane is moving in relation to the treadbelt), will the plane be able to take off".
And in my OPINION, the answer to that question is 'No'.

So in review: There are many many valid 'interpretations' of the question. But there is only 1 valid 'representation' of the question (in 'My Opinion').

You've asked a very tricky question, helped in part by your use of differing terms, I'm not sure if you meant it to confuse...but it does. That's why I have to answer with a #1 and #2.

Bruce, you told me "You (Atl5p) have claimed that the plane relative to the belt an belt relative to the ground/air is a valid interpretation."

My answer is: Yes it is true that I have claimed it to be a valid interpretation...and there are many different valid interpretations due to the wording of the OP, specifically it's failure to specify where the speeds are measured from.

I also feel that the above, IN MY OPINION, is THE "valid representation of the question".

egnorant
So we have determined that ATL5P believe the original question can be answered "Yes" with the belt not moving in relation to the ground/air.

Pretty much the description of a normal takeoff.

And that it is just as valid as the other scenario that has the plane not moving in relation to the ground/air which would yield a "No" answer.

And in ATL5Ps opinion the second scenario is the correct one!

All the while ATL5P totally rejects the idea of the plane and the belt both moving in relation to the ground/air which would result in a "Yes" answer.

The opinion of ATL5P is incorrect, but this is America....he can be wrong if he chooses......

Bruce

Gizmo
Good question, though. I agree with anyone who says that the plane will take off, due to the jet engine thrust.

Atl5p
QUOTE (egnorant+Feb 13 2007, 05:52 PM)
So we have determined that ATL5P believe the original question can be answered "Yes" with the belt not moving in relation to the ground/air.

Pretty much the description of a normal takeoff.

And that it is just as valid as the other scenario that has the plane not moving in relation to the ground/air which would yield a "No" answer.

And in ATL5Ps opinion the second scenario is the correct one!

All the while ATL5P totally rejects the idea of the plane and the belt both moving in relation to the ground/air which would result in a "Yes" answer.

The opinion of ATL5P is incorrect, but this is America....he can be wrong if he chooses......

Bruce

QUOTE
All the while ATL5P totally rejects the idea of the plane and the belt both moving in relation to the ground/air which would result in a "Yes" answer.

I'm not sure where you get the idea that I "reject the idea of the plane and the belt both moving in relation to the ground/air which would result in a "Yes" answer."

Once again Bruce:
http://forum.physorg.com/index.php?showtop...ndpost&p=177183
QUOTE (->
 QUOTE All the while ATL5P totally rejects the idea of the plane and the belt both moving in relation to the ground/air which would result in a "Yes" answer.

I'm not sure where you get the idea that I "reject the idea of the plane and the belt both moving in relation to the ground/air which would result in a "Yes" answer."

Once again Bruce:
http://forum.physorg.com/index.php?showtop...ndpost&p=177183
Bruce,
As I've stated about a billion times:

When IAS is used to determine plane speed, the plane will fly.

I'm not sure why you're finding this so difficult to understand Brucie...Each example you have listed above; they are all valid inturpretations of the OP. And in my opinion, only one of them is what I believe to be the true intent of the OP.
Everything depends on 'what' the speed is measured from...so when someone answers the question, they must specify this missing piece...whichever version they are describing.

Thus: When speed = IAS, then plane flies.
When speed = 'wheelspeed' in that the plane's speed is determined via how fast it moves over the surface of the treadbelt, and the treadbelt's speed is measured as belt speed moving past the drive motor...the plane will not fly.

But just to answer the question, without specifying how you determine 'speed', is an incomplete answer.

So, to complete my responce to your 'claim'...It should be wildly apparent that I do NOT reject the idea that 1 inturpretation could be "the plane and the belt both moving in relation to the ground/air which would result in a "Yes" answer."

Heck, the way the question is worded, and as YOU have pointed out, another inturepretation could be "Plane in relation to belt, and Belt in relation to Plane".

There are lots of inturpretations, and I do not reject any of them as being valid opinions.

My personal opinion is the same as a runner on a treadbelt, when the belt is set to 'match' the runner's speed, with the intent of keeping the runner at 0 IAS: Q: "Can you do the same thing with an air-powered vehicle.?" That is what I believe the question is asking. The plane's speed is determined by it's speed on the treadbelt....thus the purpose of the treadbelt.

And we should all know Brucie's version: "The faster a plane moves through the air, the faster the belt spins...the plane always moves through the air, it is required by the wording of the question: Q:Does the plane have airspeed?"...(and by the way, the treadbelt is disregarded.)"

Bruce, if that's what you want your version to sound like, then so be it....you have that right.

And for the final record...if that is your 'version' of the OP, and you say that the plane YES has IAS...then I agree with you...I do not reject that answer to your version and I never have. Are we clear?

Now what we are missing is where you say "Atl5p, wheelspeed version, if you want to use that version, really would have the plane not flying".

I'm sure everyone is just waiting to see you put that into print....
egnorant
QUOTE (Atl5p+Feb 14 2007, 03:11 PM)
And we should all know Brucie's version: "The faster a plane moves through the air, the faster the belt spins...the plane always moves through the air, it is required by the wording of the question:  Q:Does the plane have airspeed?"...(and by the way, the treadbelt is disregarded.)"

Just showing that your version with the plane without air/ground speed uses the same rules as a version where the belt has no air/ground speed.

By these rules that you have dreamed up, every normal takeoff is properly described as a plane moving one direction with the ground moving in the opposite direction.

The terms the plane moves and the belt moves are presented without specifics.
The solution you present REQUIRES specifics to be used.

Suppose the question had been presented as the belt moves in one direction and the plane does not move, or the plane moves in one direction and the belt does not move?

These fit you version and the inverse version (normal takeoff) unless you specify that the plane does not move RELATIVE to the belt or the belt does not move RELATIVE to the plane.

Bruce

QUOTE
And that it is just as valid as the other scenario that has the plane not moving in relation to the ground/air which would yield a "No" answer.

This is me stating that the use of your wheelspeed version will result in a no fly situation. Do you even read these things?
physics pro
QUOTE
Ok, the problem with this question is that It has 2 parts some people see the first part some people see the second, however see them together use them with each other and your outcome is the right answer.

Also lets not get all sideways by using pointless examples such as hovercraft's, rocket cars, winged cars and my favorite the match box on the treadmill. Don’t get me wrong they prove there point, but they are that far from the problem its not funny.

The first part - The wheels. Let’s make a few assumptions first,

- The wheels stay connected with the conveyor.
- The conveyor rotates at the same speed as the wheels rotate. (No velocity (speed))
-like in all theoretical physics questions friction isn’t being taken into account, don’t
Fooled. When I say friction I mean forces that work against movement.

Ok let’s say the jet/plane has just started its attempt to accelerate. (If the jet/plane accelerates ‘shows over’ it takes off). The jet/planes wheels are spinning at say… 5m/s/s so the conveyor will speed up to 5m/s/s, therefore 5 – 5 = 0 witch means no extra acceleration in ether way (yet again no velocity). It simply doesn’t move because the ‘magical’ computer connecting the jet/plane with the conveyor is so smart.

The second part- Gravity. Quick physics lesson.

- Gravity is a acceleration not a force or a energy that is why it is measured in m/s/s. (I know that there will be some smart guy that sets out to prove me wrong on this using string theory (string theory is a very advanced physics) but please let’s talk in reality for a moment)
-3rd law of motion, equal and opposite reactions.

Ok with that out of the way. Gravity’s acceleration is 9.8m/s/s down, (these are vector quantity’s not scalar don’t be confused) DOWN is the key word here because for something to achieve ‘flight’ it doesn’t need a airfoil or a jet engine all it needs to do is accelerate UP at 9.8m/s/s or more. Now the jet/plane exerts force backward to go forward, eg thrust or pushing more air backward. Is the force being pushed down to active an UPward acceleration? NO (F=M.a). The force being created by the thrust is being countered (opposite reaction) by the magical conveyor. (Because we know that the force can’t disappear). By the way jump jets are a different matter.

In closing, the conveyor keeps up with the jet/plane so I can’t go forward.
And it cant go up unless it pushes force down accelerating up.
Without these the plane isn’t going anywhere.

By the way I’m only 16

I would also like to take the time out to say who ever came up with this question is twice as smart as the answer.

Im changing my answer, part 1 is incorrect. I realize were I went wrong the force isn’t being equaled out by the conveyor because no force is being pushed though the wheels. wheel speed is irrelevant. the rest is fine. i put it down to miss interpretation of question lol.

So force out the back, opposite reaction would be the jet/plane moving forward. There for taking off.

Fynlcut
many other people did the same thing!
rethinker
Way to go Physics Pro
gmilam
I love it when the light comes on. Good job!
Atl5p
QUOTE (physics pro+Feb 15 2007, 01:34 AM)

Im changing my answer, part 1 is incorrect. I realize were I went wrong the force isn’t being equaled out by the conveyor because no force is being pushed though the wheels. wheel speed is irrelevant. the rest is fine. i put it down to miss interpretation of question lol.

So force out the back, opposite reaction would be the jet/plane moving forward. There for taking off.

Hmmm, let's think through this...

Take a shopping cart and put it on a treadbelt...now fill the cart up with lead weights until it weighs 2000lbs. (make sure the treadbelt is sturdy!)

You stand on the solid ground, and hold onto the handlebar. Now turn on the treadbelt. Is the cart pushing back towards you? No?

Increase the speed of the treadbelt. Is the cart now pushing harder towards you? NO?

Well, it seems you must have a magic cart then....because we should all know that a force is being transmitted, and that force will increase as you increase the speed of the treadbelt.

C'mon man....think!
egnorant
QUOTE (Atl5p+Feb 15 2007, 06:07 PM)
Hmmm, let's think through this...

Take a shopping cart and put it on a treadbelt...now fill the cart up with lead weights until it weighs 2000lbs. (make sure the treadbelt is sturdy!)

You stand on the solid ground, and hold onto the handlebar. Now turn on the treadbelt. Is the cart pushing back towards you? No?

Increase the speed of the treadbelt. Is the cart now pushing harder towards you? NO?

Well, it seems you must have a magic cart then....because we should all know that a force is being transmitted, and that force will increase as you increase the speed of the treadbelt.

C'mon man....think!

Good thing this loaded cart is not moving in your direction like the belt is!!

Bet it would mash you like....Well, a ton of lead!!

Bruce

Atl5p
QUOTE (egnorant+Feb 15 2007, 01:35 PM)
Good thing this loaded cart is not moving in your direction like the belt is!!

Bet it would mash you like....Well, a ton of lead!!

Bruce

You prove over and over just how insightful you are....way to go Brucie!
physics pro
QUOTE
Explination with actual formula:
If the plane rolls forward 1 meter, the plane expends 836 Kjoules, and the runway expends 88 Kjoules to try to stop it by "moving" in the opposite direction. But if the runway could somehow move fast enough to expend the same 836 Kjoules as the plane, it [/I]could[I] "hold" it in place. 836/88 = 9.5 so the runway needs to "move" 9.5 farther than the plane to prevent it from making any headway. So the "control system" needs to tune the conveyor/runway to move 9.5 times faster than the plane.
--FlyBoy

So, I take this to mean the following:
If a plane can normally go 100mph on static runway, then it would take a 950mph treadbelt to hold the plane at 0 IAS. When this happens, the treadbelt speed will match exactly the plane's wheelspeed.

You're credibility is shot, Bloy....don't bother wasting your time with me again....I do not consider you a player any longer....you are a pretender....

lol ATl5p i just read your blue writing below that cart 'idea' you had. Haha, it amuses me because your physics are shocking. Firstly your not using fundamental measurements of physical quantities that are recognized though the world eg. You say mph when u should be using m/s. are you American? Imperial… catch up to the rest of the metric.

And in your argument you’re using joules. This is a measure of energy; you should be using force in measured in newtons. Because force is directly related to acceleration (m/s/s) energy is not. Energy has also yet to be defined.

QUOTE (->
 QUOTE Explination with actual formula:If the plane rolls forward 1 meter, the plane expends 836 Kjoules, and the runway expends 88 Kjoules to try to stop it by "moving" in the opposite direction. But if the runway could somehow move fast enough to expend the same 836 Kjoules as the plane, it [/I]could[I] "hold" it in place. 836/88 = 9.5 so the runway needs to "move" 9.5 farther than the plane to prevent it from making any headway. So the "control system" needs to tune the conveyor/runway to move 9.5 times faster than the plane.--FlyBoySo, I take this to mean the following:If a plane can normally go 100mph on static runway, then it would take a 950mph treadbelt to hold the plane at 0 IAS. When this happens, the treadbelt speed will match exactly the plane's wheelspeed.You're credibility is shot, Bloy....don't bother wasting your time with me again....I do not consider you a player any longer....you are a pretender....

lol ATl5p i just read your blue writing below that cart 'idea' you had. Haha, it amuses me because your physics are shocking. Firstly your not using fundamental measurements of physical quantities that are recognized though the world eg. You say mph when u should be using m/s. are you American? Imperial… catch up to the rest of the metric.

And in your argument you’re using joules. This is a measure of energy; you should be using force in measured in newtons. Because force is directly related to acceleration (m/s/s) energy is not. Energy has also yet to be defined.

Hmmm, let's think through this...

Take a shopping cart and put it on a treadbelt...now fill the cart up with lead weights until it weighs 2000lbs. (make sure the treadbelt is sturdy!)

You stand on the solid ground, and hold onto the handlebar. Now turn on the treadbelt. Is the cart pushing back towards you? No?

Increase the speed of the treadbelt. Is the cart now pushing harder towards you? NO?

Well, it seems you must have a magic cart then....because we should all know that a force is being transmitted, and that force will increase as you increase the speed of the treadbelt.

C'mon man....think!

Now with your basic physics lesson out of the way. Referring to your blog on page 468, the only reason that the cart will be pushing back is because of friction, in theoretical physics questions the rest of the world. And you are wrong about that force been transmitted. There is a force however its not working in the way your saying.

The force your talking about its pushing UP (vector) against the gravity witch is pushing DOWN (vector). The key is that the wheels spin freely. Don’t worry its something I didn’t understand at first ether. There fore if the wheels spin freely there is no force going though them. The only force is the minute amount of friction.

Think of it this way. Say the all the force from the treadmill is going though the wheels, do you really think you could hold it still?
Fynlcut
Alt5p wants to be different, so he claims the planes speed is measured by the turning of the wheels. To back his theory, he has twisted, tangled, and otherwise contorted physics, logic, and sanity to fit his needs.

At one point he argued forces, but kept saying wheelspeed, wheelspeed, wheelspeed. He even went so far as drawing a diagram showing the forces at work. Mind you he didn't include wheels in that one, just a plane attached to a belt. Now he says if the belt spins at some ludicrous speed it will hold the plane at full power. He did attempt to do an experiment. His reported outcome satisfied his theory, but he provided no proof, and the control was somewhat questionable to say the least.

His wheelspeed theory is nothing more than an exercise in balancing forces. Can you balance the forces? Yes rather easily, does the question say to balance forces? No it says make the plane go, and see what effect a conveyor moving the opposite way, at the same time, has on said plane.

Bruce and even Alt5p have shown that you can contort the question to come up with a multitude of outcomes, but the most logical outcome, the conveyor has little effect and the plane is soon doing loopty loops overhead.
physics pro
please if anyone still thinks the aircraft will take of please feel free to post here with your explanation. i and many others will cut down your therory/reason in 24 hours.

Derek1148
QUOTE (physics pro+Feb 18 2007, 08:20 AM)
please if anyone still thinks the aircraft will take of please feel free to post here with your explanation. i and many others will cut down your therory/reason in 24 hours.

That is a negative approach to scientific research. Propose nothing but prepare to attack others.

Why don’t you or one of the “many others” present your specific theories on the plane’s inability to take off?

egnorant
QUOTE (physics pro+Feb 18 2007, 08:20 AM)
please if anyone still thinks the aircraft will take of please feel free to post here with your explanation. i and many others will cut down your therory/reason in 24 hours.

It will take off!
Plane moves one direction...lets say East.
Belt moves opposite direction....opposite of East is West.
Plane moves East at takeoff speed while the belt is moving at the same speed West.
Plane flies!
You and many others are now on the clock....24 hours right?

Bruce

Skum of the universe
I do not believe the plane will take off in this situation because if it didn't need the forward momentum to take off (the forward momentum that it Wouldn't have in this situation) then we wouldn't have built runways at all, but I am by no means any kind of an expert on airplanes, just my opinion.
Grumpy
QUOTE
A plane is standing on 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 opposite direction).

The question is:

Will the plane take off or not? Will it be able to run up and take off?

Of course it will take off!!! The belt is keyed to the speed of the aircraft and CANNOT move unless the aircraft moves and then it will move in the opposite direction at the same speed.

In a normal aircraft this will cause the wheels to turn twice as fast, but this will have little effect on the aircraft due only to rolling resistence.

The point is the only way the belt has of affecting the aircraft is through the wheels. Since wheels are there to eliminate friction there is very little effect that can be transfered through them. Before significant resistence can be transfered through the wheels the aircraft will have reached takeoff speed and the wheels will only be going at twice their normal speed.

If the aircraft has hover pads instead of wheels(eliminating ALL resistence to forward motion)it will also take off and it will not make the least bit of difference how fast the belt moves, or in which direction.

Aircraft, by definition, move through the air. Their motive power is applied to the air, not the wheels. Their speed is measured by their motion through the air, not over the ground.

The Slepcev Storch is a two seat tandem, Short Take-Off and Landing, (STOL), aircraft with some amazing capabilities.

The original "Storch", (German for stork), was designed in 1936, Germany, by Dr. Gerhard Fieseler, and played an important role for the Luftwaffe in the Second World War as a reconnaissance utility and personnel carrying aircraft.

The Slepcev Storch is the design of Nestor Slepcev, Cenej Novi Sad, SCG, and is a 3/4 scale version of the original. Modified in areas for simplicity, the Slepcev Storch had dual controls and two seats in tandem.

By keeping the weight down to a minimum, yet keeping the aircraft structurally still very strong, (+6 -3), the Slepcev Storch is very original in both appearance and performance. The aircraft will fly at 22mph at full flap and 30% of power. Take off run into a 16mph wind is vertical with no forward roll.

http://www.slepcevstorch.com/
Skum of the universe
Good explanation.
Skum of the universe
actually on reflection i agree that it will take off, because assuming the wheels are well lubricated the plane will still move forward, and thus be able to take off, if because the wheels asre just there so that the planes not scraping against pavement, their not actually moving the plane, the proppellers are, so resistance on the wheels will just create more friction, and it will take more force to accelerate the plane enough to lift off, but not stop it completely, unless its a really weak plane. in my opinion
egnorant
QUOTE (Skum of the universe+Feb 19 2007, 03:23 AM)
actually on reflection i agree that it will take off, because assuming the wheels are well lubricated the plane will still move forward, and thus be able to take off, if because the wheels asre just there so that the planes not scraping against pavement, their not actually moving the plane, the proppellers are, so resistance on the wheels will just create more friction, and it will take more force to accelerate the plane enough to lift off, but not stop it completely, unless its a really weak plane. in my opinion

You need to only look at your post to find the truth.
The number one flawed asumption is that the belt will
"stop the plane from moving forwards"
A plane moves one direction at 30 mph...something comes along and stops it from moving at 30 mph..is the plane still moving at 30 mph?

When you say a really weak plane, are you saying that 30 mph in one direction is somehow different than 30 mph in one direction for a really powerful plane?

Which is faster? A hovercraft at 30 mph or a 757 being dragged on its belly at 30 mph?

Forces involved are not a factor.

Bruce

egnorant
QUOTE (physics pro+Feb 18 2007, 08:20 AM)
please if anyone still thinks the aircraft will take of please feel free to post here with your explanation. i and many others will cut down your therory/reason in 24 hours.

Well, that was brutal!

Bruce
Atl5p
QUOTE (physics pro+Feb 16 2007, 02:01 AM)

lol ATl5p i just read your blue writing below that cart 'idea' you had. Haha, it amuses me because your physics are shocking. Firstly your not using fundamental measurements of physical quantities that are recognized though the world eg. You say mph when u should be using m/s. are you American? Imperial… catch up to the rest of the metric.

And in your argument you’re using joules. This is a measure of energy; you should be using force in measured in newtons. Because force is directly related to acceleration (m/s/s) energy is not. Energy has also yet to be defined.

Now with your basic physics lesson out of the way. Referring to your blog on page 468, the only reason that the cart will be pushing back is because of friction, in theoretical physics questions the rest of the world. And you are wrong about that force been transmitted. There is a force however its not working in the way your saying.

The force your talking about its pushing UP (vector) against the gravity witch is pushing DOWN (vector). The key is that the wheels spin freely. Don’t worry its something I didn’t understand at first ether. There fore if the wheels spin freely there is no force going though them. The only force is the minute amount of friction.

Think of it this way. Say the all the force from the treadmill is going though the wheels, do you really think you could hold it still?

First off, please be aware that the part of my 'sig' which has "-FlyBoy" at the end, was NOT written by me, it was written by a 'FlyBoy'. I am not a 'FlyBoy', as is evidenced by the fact that I believe the plane will 'Not fly'.
So, Joules and MPH was not from me, sorry.

Otherwise, in responce to your observations of the loaded down cart on the treadbelt....you never said what you though would happen. By disagreeing with me, I can only assume that you believe the following:

"A cart loaded down with heavy weights is on a treadbelt. PhysicsPro is holding onto the handlebar and is standing on the ground. The treadbelt is started, and the speed is increased, faster and faster. The force pushing the cart backwards onto PhysicsPro will never increase, no matter how fast the treadbelt spins...in fact, there is no force pushing back at all."

So, is that what you are saying?
Atl5p
QUOTE (Grumpy+Feb 18 2007, 09:28 PM)

Of course it will take off!!! The belt is keyed to the speed of the aircraft and CANNOT move unless the aircraft moves and then it will move in the opposite direction at the same speed.

In a normal aircraft this will cause the wheels to turn twice as fast, but this will have little effect on the aircraft due only to rolling resistence.

The point is the only way the belt has of affecting the aircraft is through the wheels. Since wheels are there to eliminate friction there is very little effect that can be transfered through them. Before significant resistence can be transfered through the wheels the aircraft will have reached takeoff speed and the wheels will only be going at twice their normal speed.

If the aircraft has hover pads instead of wheels(eliminating ALL resistence to forward motion)it will also take off and it will not make the least bit of difference how fast the belt moves, or in which direction.

Aircraft, by definition, move through the air. Their motive power is applied to the air, not the wheels. Their speed is measured by their motion through the air, not over the ground.

The Slepcev Storch is a two seat tandem, Short Take-Off and Landing, (STOL), aircraft with some amazing capabilities.

The original "Storch", (German for stork), was designed in 1936, Germany, by Dr. Gerhard Fieseler, and played an important role for the Luftwaffe in the Second World War as a reconnaissance utility and personnel carrying aircraft.

The Slepcev Storch is the design of Nestor Slepcev, Cenej Novi Sad, SCG, and is a 3/4 scale version of the original. Modified in areas for simplicity, the Slepcev Storch had dual controls and two seats in tandem.

By keeping the weight down to a minimum, yet keeping the aircraft structurally still very strong, (+6 -3), the Slepcev Storch is very original in both appearance and performance. The aircraft will fly at 22mph at full flap and 30% of power. Take off run into a 16mph wind is vertical with no forward roll.

http://www.slepcevstorch.com/

So, you say the question is asking this:
"An airplane moves through the air....does the airplane move though the air?"
Wow, I'm proud of you for answering that correctly!!! Go now and get yourself a cookie!

Also you say that the plane's speed MUST ALWAYS be related to the surrounding atmosphere...
"Their speed is measured by their motion through the air, not over the ground. "-Grumpy
First off, I'd beg to differ...planes used to crash using the above method...when flying from point A to point B on planet earth in the fog and clouds and over a mountian, what is more important? Airspeed or Groundspeed?
"Hey, how long until we decend? If we overshoot the airport, we'll run into a mountianside." -- Dead Pilot.

Also, by using strictly IAS to determine plane's speed...what if we used a wind tunnel instead of a treadbelt? Your IAS speed will result in a plane that is flying, but not 'moving' in relation to the ground. That would go against Bruce's claim that the plane 'Moves', right?
"Plane moves East at takeoff speed while the belt is moving at the same speed West.
Plane flies!" --Bruce.

See, Grumpy says IAS is the plane's speed.
Bruce says 'Groundspeed' is the plane's speed.
I say that 'Speed over surface of treadbelt' is the plane's speed.

And the way the question is worded, none of us, no not one, can say which is correct...because the OP NEVER NEVER NEVER specifies 'what' to measure the plane's speed against.

Grumpy, I would suggest that you and Bruce do some PM'ing to get the story straight.....and I thought you guys had worked all this out. But now it seems that just 'anything to get it flying' will work for you guys....
"it doesn't MATTER where the speed is measured from, it could the the air, or the ground, as long as ATL is wrong, we are happy"....is that it? HAHA!
Derek1148
QUOTE (Atl5p+Feb 19 2007, 04:34 PM)
And the way the question is worded, none of us, no not one, can say which is correct...because the OP NEVER NEVER NEVER specifies 'what' to measure the plane's speed against.

In that the author of the original post chose English to pose his scenario, the primary definition of “move” is relative.

STANDARD COLLEGE DICTIONARY, Funk and Wagnalls: "move": 1. To change place or position; go to or from a place; transfer; shift.

A plane with its wheels spinning while remaining stationary does not seem to meet that definition.

The scenario seems to pose the question: Would the plane’s movement (relative to the earth's surface) in one direction and the conveyor’s movement in the opposite direction, create an impediment to take off?
Grumpy
Atl5p

QUOTE
Also, by using strictly IAS to determine plane's speed...what if we used a wind tunnel instead of a treadbelt? Your IAS speed will result in a plane that is flying, but not 'moving' in relation to the ground.

But it is moving(and flying) in relation to the air. And there you have your answer, aircraft OPERATE only upon airspeed, they NAVIGATE using groundspeed, this is not a navigation problem. The original question is will it take-off(operate), not "where will it go?"(navigate).

QUOTE (->
 QUOTE Also, by using strictly IAS to determine plane's speed...what if we used a wind tunnel instead of a treadbelt? Your IAS speed will result in a plane that is flying, but not 'moving' in relation to the ground.

But it is moving(and flying) in relation to the air. And there you have your answer, aircraft OPERATE only upon airspeed, they NAVIGATE using groundspeed, this is not a navigation problem. The original question is will it take-off(operate), not "where will it go?"(navigate).

Also you say that the plane's speed MUST ALWAYS be related to the surrounding atmosphere...
"Their speed is measured by their motion through the air, not over the ground. "-Grumpy
First off, I'd beg to differ...planes used to crash using the above method...when flying from point A to point B on planet earth in the fog and clouds and over a mountian, what is more important? Airspeed or Groundspeed?
"Hey, how long until we decend? If we overshoot the airport, we'll run into a mountianside." -- Dead Pilot.

Here you are again confusing OPERATION of the aircraft(based SOLELY on it's speed relative to the air, see cited plane that takes off vertically in a 16 mph headwind and ZERO groundspeed) with NAVIGATION of the aircraft(where it is going in relation to ground features like mountains and airports). THIS IS NOT A NAVIGATION PROBLEM, THE QUESTION ONLY ASKS "WILL IT OPERATE?"

QUOTE
And the way the question is worded, none of us, no not one, can say which is correct...because the OP NEVER NEVER NEVER specifies 'what' to measure the plane's speed against.

Wrong again, the belt is coupled to the speed of the aircraft, the aircraft must move for the belt to move and then it must move in the opposite direction at the same speed as the plane. Since no wind was specified we must assume zero wind, therefore aircraft speed and IAS are the same. Therefore my plane will be doing 16 mph on takeoff while the belt will be travelling 16 mph in the opposite direction and the planes wheels will be turning at 32 mph.

'Bye now, I'm going flying. See Ya'.

Grumpy
egnorant
QUOTE (Atl5p+Feb 19 2007, 04:22 PM)
"A cart loaded down with heavy weights is on a treadbelt.  PhysicsPro is holding onto the handlebar and is standing on the ground.  The treadbelt is started, and the speed is increased, faster and faster.  The force pushing the cart backwards onto PhysicsPro will never increase, no matter how fast the treadbelt spins...in fact, there is no force pushing back at all."

So, is that what you are saying?

Even with any increase in force it still does not move!
Please state what direction said cart is "moving".

QUOTE
See, Grumpy says IAS is the plane's speed.
Bruce says 'Groundspeed' is the plane's speed.
I say that 'Speed over surface of treadbelt' is the plane's speed.

In this situation the term groundspeed and airspeed are interchangeable.
But what direction do you say the plane is moving in?
This would help determine what the opposite direction is.

QUOTE (->
 QUOTE See, Grumpy says IAS is the plane's speed.Bruce says 'Groundspeed' is the plane's speed.I say that 'Speed over surface of treadbelt' is the plane's speed.

In this situation the term groundspeed and airspeed are interchangeable.
But what direction do you say the plane is moving in?
This would help determine what the opposite direction is.

Grumpy, I would suggest that you and Bruce do some PM'ing to get the story straight.....and I thought you guys had worked all this out. But now it seems that just 'anything to get it flying' will work for you guys....
"it doesn't MATTER where the speed is measured from, it could the the air, or the ground, as long as ATL is wrong, we are happy"....is that it? HAHA!

No need to PM each other...We just use common and accepted rules for the measurement of items as described in the original question.
It is not our fault you are wrong!

Bruce

gmilam
QUOTE (egnorant+Feb 19 2007, 06:52 AM)
Well, that was brutal!

Bruce

Hey, he admitted he was wrong. That alone earns him many points in my book.
egnorant
QUOTE (gmilam+Feb 20 2007, 12:22 AM)
Hey, he admitted he was wrong. That alone earns him many points in my book.

He did? PhysicsPoor...whatever?
I just saw a request for info that he and others could rebut and then nothing happened.

Bruce
jacobsg
QUOTE (Atl5p+Feb 19 2007, 04:34 PM)
So, you say the question is asking this:
"An airplane moves through the air....does the airplane move though the air?"
Wow, I'm proud of you for answering that correctly!!!  Go now and get yourself a cookie!

So, you say the question is asking this:
"An airplane [doesn't] move[s] through the air....does the airplane move though the air?"
Wow, I'm proud of you for answering that correctly!!! Go now and get yourself a cookie!
Atl5p
Derek1148

Derek, I like your definition:” STANDARD COLLEGE DICTIONARY, Funk and Wagnalls: "move": 1. To change place or position; go to or from a place; transfer; shift.”

As in “Movement of the plane in RELATION TO THE BELT” Imagine the treadbelt has dotted lines, and is 2 miles long (the length of the local Navy Air Reserve Base). The plane “MOVES” by your definition, or changes position in relation to those dotted lines, ie “IN RELATION TO THE TREABELT’S SURFACE”

I pray that you can see how that works….see, you are doing something that the OP NEVER says to do…you are standing on the earth, off to the side of the treadbelt, and you are judging the plane’s speed from YOUR position. HINT: The OP NEVER says you are there, or if you are there, WHERE you are…AND the question NEVER says to use YOU as the basis for the plane’s speed.

Glad I could clear that up for you.

Grumpy

Most flyboys are seeing ‘Plane Moves’ as meaning ‘Moves in relation to the earth’….YOU disagree with MOST of the FlyBoys by saying that a plane’s ‘Movement’ is only “though the air”. I just think it’s very funny that you seem to disagree with FlyBoys, but still say it flies. It seems like you and the FlyBoys will say anything, as long as the plane flies.

Sorta like your hairsplitting of ‘Operation’ and ‘Navigation’…wow, that is BRAND NEW….anyone else care to comment on that? You said
“THE QUESTION ONLY ASKS "WILL IT OPERATE?"
Grumpy, the OP never uses those words, so I’m not sure why you are saying this…

Also, I’m wondering why you didn’t introduce the intricacies of ‘Operation’ and ‘Navigation’ When you gave the following definition:

“Aircraft, by definition, move through the air. Their motive power is applied to the air, not the wheels. Their speed is measured by their motion through the air, not over the ground.” – Grumpy

You were VERY clear…ONLY THE AIR….but now you say ‘Navigation’ is different….ummm, ok.

Yeah, you’ll say anything….you’re loosing credibility. Sorry for you! It seems like you are trying to break the entire debate into whether or not the plane is ‘Operating’ or ‘Navigating’…you seem to be saying that if the plane was ‘Navigating’ on the treadbelt that it would NOT fly…but you believe it is actually ‘Operating’ so it DOES fly…..dude, that is some crazy she-at.

Grumpy, you say “aircraft speed and IAS are the same”

That is an OPINION…not ‘Fact’.

I say “aircraft speed and wheelspeed are the same”
Again…another opinion…not Fact.

jacobsg

No, I say the question is asking this:
“Can a treadbelt prevent a plane from taking off”

And that is an OPINION.

And Bruce...you say you are using "common and accepted rules for the measurement of items as described in the original question"

I sure don't know what the heck that means....you are using what you call 'Groundspeed' and Grumpy is using 'Airspeed', and they are NOT interchangeable....the question does not mention wind...therefore we don't know WHAT the wind is doing...we cannot assume there is NO wind just because it isn't mentioned. Dosn't say that there is AIR either...so should we assume that there is NO AIR? Hardly.

If a plane's is on a treadbelt, it's SPEED is based on the surface of the treadbelt....that is my opinion.... and it is based on common and accepted rules for the measurement of items as described in the original question, in MY OPINION.

Bruce, you are not 'wrong' any more than I am 'wrong'.

Bruce, the OP never states "...and YOU are standing off to the side, and the plane's speed is based from your vantage point..." you are imagining this in you head.

I on the other hand choose not to be a passive observer. I say 'Hey, if that plane needs a pilot, then it's going to be ME".
So, I got into the plane, then it got foggy, and all I could see was a few feet in front of the airplane...I could see the dashed lines on the surface of the movable 'runway'/treadbelt. I fire up the engines and see those lines "MOVING" under the plane...thus I know I am "MOVING" over those lines....I have 'SPEED' over those lines, and the OP says the treadbelt is matching that SPEED.

I open the window and stick my arm out, and there is little if any wind (IAS).

It's not 'Wrong'...it's a different opinion than yours.
Derek1148
QUOTE (Atl5p+Feb 20 2007, 09:59 PM)
Derek1148

Derek, I like your definition:” STANDARD COLLEGE DICTIONARY, Funk and Wagnalls: "move": 1. To change place or position; go to or from a place; transfer; shift.”

As in “Movement of the plane in RELATION TO THE BELT” Imagine the treadbelt has dotted lines, and is 2 miles long (the length of the local Navy Air Reserve Base). The plane “MOVES” by your definition, or changes position in relation to those dotted lines, ie “IN RELATION TO THE TREABELT’S SURFACE”

I pray that you can see how that works….see, you are doing something that the OP NEVER says to do…you are standing on the earth, off to the side of the treadbelt, and you are judging the plane’s speed from YOUR position. HINT: The OP NEVER says you are there, or if you are there, WHERE you are…AND the question NEVER says to use YOU as the basis for the plane’s speed.

Glad I could clear that up for you.

What I was attempting to demonstrate to you was that your interpretation of the scenario was not the only one that can be reasonably drawn.

The issue is, within the scope of the author’s scenario, will the plane be capable of take-off. Not contort the scenario into a “no-fly” situation. The author did not preclude striking the plane with a RPG while on the tarmac, either.

Twisting logic serves no purpose in science.

zep
The force that moves the plane forward is the thrust from the jet engine, the thrust pushes against the air and the air pushes back moving the plane forward reguardless of its wheels, the plane will take off-the conveyor belt infomation is infomation designed to confuse the question and make it seem more difficult than it is-the only force acting on the plane is the thrust from the engine. If you could put the plane in water and a car in water the plane would move forward due to the thrust acting on the plane, the car could not move forward cause its movement is dependent on the drive wheels, where the plane is not dependent on wheels to move forward.

Zep
Atl5p
QUOTE (Derek1148+Feb 20 2007, 05:36 PM)
What I was attempting to demonstrate to you was that your interpretation of the scenario was not the only one that can be reasonably drawn.

The issue is, within the scope of the author’s scenario, will the plane be capable of take-off. Not contort the scenario into a “no-fly” situation. The author did not preclude striking the plane with a RPG while on the tarmac, either.

Twisting logic serves no purpose in science.

WRONG!

You were NOT: "attempting to demonstrate to you was that your interpretation of the scenario was not the only one that can be reasonably drawn. "

You were ACTUALLY trying to DISAGREE with my stated opinion, and then went on to state why YOUR opinion was THE correct one...and I quote:

QUOTE
A plane with its wheels spinning while remaining stationary does not seem to meet that definition.

The scenario seems to pose the question: Would the plane’s movement (relative to the earth's surface) in one direction and the conveyor’s movement in the opposite direction, create an impediment to take off?

I wholeheartedly disagree with your OPINION, although I agree that your opinion cannot be disproven, nor can mine.

In my OPINION, the question is clearly asking us "Is a treadbelt able to prevent a plane from taking off".

And what is MOST laughable of your statement? The fact that you were originally responding to a statement that I HAD MADE where I was stating that my interpretation of the scenario was not the only one that can be reasonable drawn!!!

See, that is what happened....I was saying that there are any number of interpretations that can be drawn, due to the lack of specifics in the OP...then YOU defined 'MOVE' for us and at the same time said my OPINION was WRONG.....then I re-clarified to YOU that by YOUR definition, 'MOVE' can be = wheelspeed as well as groundspeed (it could be either)....and then you are NOW claiming to be demonstrating to ME that more than one OPINION can exist???!?!?!

What's next? Are you going to now say that only YOUR opinion is correct.....and THEN once AGAIN say that more than one scenerio could be correct....and then say that only YOUR scenerio is correct....only to then re-iterate that more than 1 version can exist???

WOW...are we in a time warp? Is my name now Derek1148??? Is this like 2001 space odesy and you are me, and we can communicate with each other, and then become each other!?!?!

Finally, after you cleared everything up about there being more than 1 scenario that can be 'reasonably drawn', you seem to be acusing me of 'Twisting Logic' just because I can recognise that there can be more than 1 scenario???
???

You have either
1) Forgotten to take your meds
or
2) Taken too many of your meds.

1st off:
Please show me where the plane has a "Jet" engine in the OP?
2nd
Please show me where the plane has "wheels" in the op?
3rd
Basically what you have said is that an 'air powered vehicle' (as opposed to a wheel driven vehicle), in a body of water, will NOT be affected by currents.
So that means that YOU BELIEVE that a SAILBOAT while under sail power only, will NOT be affected by water currents? But as SOON as he starts the propellor spinning, the currents will then affect the boat.

You have alot of reading to do....470 pages....see you soon!
Grumpy
Atl5p

QUOTE

Most flyboys are seeing ‘Plane Moves’ as meaning ‘Moves in relation to the earth’….YOU disagree with MOST of the FlyBoys by saying that a plane’s ‘Movement’ is only “though the air”. I just think it’s very funny that you seem to disagree with FlyBoys, but still say it flies. It seems like you and the FlyBoys will say anything, as long as the plane flies.

So what is movement of the belt in relation to??? The OP says the belt must move at exactly the speed that the aircraft moves but in the opposite direction. Airplane one direction, belt exactly opposite, this implys(by logic) an unmoving point in the middle that both speeds can be measured from, IE a point on the ground , not the belt.

The planes airspeed and groundspeed are exactly the same if there is no wind. Since no non-zero value was specified we are justified in thinking the windspeed is zero.

QUOTE (->
 QUOTE Most flyboys are seeing ‘Plane Moves’ as meaning ‘Moves in relation to the earth’….YOU disagree with MOST of the FlyBoys by saying that a plane’s ‘Movement’ is only “though the air”. I just think it’s very funny that you seem to disagree with FlyBoys, but still say it flies. It seems like you and the FlyBoys will say anything, as long as the plane flies.

So what is movement of the belt in relation to??? The OP says the belt must move at exactly the speed that the aircraft moves but in the opposite direction. Airplane one direction, belt exactly opposite, this implys(by logic) an unmoving point in the middle that both speeds can be measured from, IE a point on the ground , not the belt.

The planes airspeed and groundspeed are exactly the same if there is no wind. Since no non-zero value was specified we are justified in thinking the windspeed is zero.

Sorta like your hairsplitting of ‘Operation’ and ‘Navigation’…wow, that is BRAND NEW….anyone else care to comment on that? You said
“THE QUESTION ONLY ASKS "WILL IT OPERATE?"
Grumpy, the OP never uses those words, so I’m not sure why you are saying this…

Operation of the aircraft is obtaining sufficient airspeed for the plane to fly.

Navigation of the aircraft is moving it from point A on the ground to point B on the ground.

In an aircraft that can fly(operate) at 25 mph that is facing into a 25 mph wind the aircraft is stationary to the ground, IE the aircraft is operating at ZERO groundspeed. Groundspeed is not important to the operation(flying) of the aircraft, in a steady 25 mph wind that plane will hover in place over one point on the ground all day(until it runs out of fuel) maintaining a 25 mph AIRSPEED.

The OP asks will the plane fly(operate) not where it is flying to(Navigation), so the only important perameter is AIRSPEED.

QUOTE
QUOTE (->
 QUOTE Also, I’m wondering why you didn’t introduce the intricacies of ‘Operation’ and ‘Navigation’ When you gave the following definition: “Aircraft, by definition, move through the air. Their motive power is applied to the air, not the wheels. Their speed is measured by their motion through the air, not over the ground.” – Grumpy

The bold above is another way of saying airspeed.

The reason I had to go into the difference is your statement...

QUOTE
Also, by using strictly IAS to determine plane's speed...what if we used a wind tunnel instead of a treadbelt? Your IAS speed will result in a plane that is flying, but not 'moving' in relation to the ground.

And this statement...

QUOTE (->
 QUOTE Also, by using strictly IAS to determine plane's speed...what if we used a wind tunnel instead of a treadbelt? Your IAS speed will result in a plane that is flying, but not 'moving' in relation to the ground.

And this statement...

Also you say that the plane's speed MUST ALWAYS be related to the surrounding atmosphere...
"Their speed is measured by their motion through the air, not over the ground. "-Grumpy
First off, I'd beg to differ...planes used to crash using the above method...when flying from point A to point B on planet earth in the fog and clouds and over a mountian, what is more important? Airspeed or Groundspeed?
"Hey, how long until we decend? If we overshoot the airport, we'll run into a mountianside." -- Dead Pilot.

Both of which indicates to a reasonable person that you are confusing moving through the air with movement over the ground. When a plane is in the air the airspeed is all that is important to the plane remaining in the air(operating).

Only if you wish to go from point A to point B on the ground do you do the necessary calculations to determine groundspeed(airspeed+windspeed and direction) and heading to compensate for crosswind(Navigation).

The OP is only concerned with "will it fly"(operate), therefore airspeed is the only important perameter.

QUOTE
Yeah, you’ll say anything….you’re loosing credibility. Sorry for you! It seems like you are trying to break the entire debate into whether or not the plane is ‘Operating’ or ‘Navigating’…you seem to be saying that if the plane was ‘Navigating’ on the treadbelt that it would NOT fly…but you believe it is actually ‘Operating’ so it DOES fly…..dude, that is some crazy she-at.

No, the aircraft will fly no matter how you measure the speed, the belt has no mechanism to restrain the plane(without violating the "same speed" part of the OP, IE you cannot posit infinite speed for the belt). The friction generated by the wheels is the only way the belt can affect the aircraft, this extra friction is negligable. When the engine of the plane is set to takeoff power the plane will accelerate to takeoff speed no matter what the belt does. That is not an opinion, it is a fact.

QUOTE (->
 QUOTE Yeah, you’ll say anything….you’re loosing credibility. Sorry for you! It seems like you are trying to break the entire debate into whether or not the plane is ‘Operating’ or ‘Navigating’…you seem to be saying that if the plane was ‘Navigating’ on the treadbelt that it would NOT fly…but you believe it is actually ‘Operating’ so it DOES fly…..dude, that is some crazy she-at.

No, the aircraft will fly no matter how you measure the speed, the belt has no mechanism to restrain the plane(without violating the "same speed" part of the OP, IE you cannot posit infinite speed for the belt). The friction generated by the wheels is the only way the belt can affect the aircraft, this extra friction is negligable. When the engine of the plane is set to takeoff power the plane will accelerate to takeoff speed no matter what the belt does. That is not an opinion, it is a fact.

Grumpy, you say “aircraft speed and IAS are the same”

Only when wind speed is ZERO. Then(and only then) the plane's groundspeed and it's IAS are the same. That too is a fact.

QUOTE
I say “aircraft speed and wheelspeed are the same”
Again…another opinion…not Fact.

No aircraft ever built has a speedometer measuring wheelspeed, it is irrelivant to the operation of the plane and is never measured. So you are simply wrong, as usual.

Grumpy
Derek1148
QUOTE (Atl5p+Feb 20 2007, 11:52 PM)
WRONG!

You were NOT: "attempting to demonstrate to you was that your interpretation of the scenario was not the only one that can be reasonably drawn. "

You were ACTUALLY trying to DISAGREE with my stated opinion, and then went on to state why YOUR opinion was THE correct one...and I quote:

I wholeheartedly disagree with your OPINION, although I agree that your opinion cannot be disproven, nor can mine.

In my OPINION, the question is clearly asking us "Is a treadbelt able to prevent a plane from taking off".

And what is MOST laughable of your statement? The fact that you were originally responding to a statement that I HAD MADE where I was stating that my interpretation of the scenario was not the only one that can be reasonable drawn!!!

See, that is what happened....I was saying that there are any number of interpretations that can be drawn, due to the lack of specifics in the OP...then YOU defined 'MOVE' for us and at the same time said my OPINION was WRONG.....then I re-clarified to YOU that by YOUR definition, 'MOVE' can be = wheelspeed as well as groundspeed (it could be either)....and then you are NOW claiming to be demonstrating to ME that more than one OPINION can exist???!?!?!

What's next? Are you going to now say that only YOUR opinion is correct.....and THEN once AGAIN say that more than one scenerio could be correct....and then say that only YOUR scenerio is correct....only to then re-iterate that more than 1 version can exist???

WOW...are we in a time warp? Is my name now Derek1148??? Is this like 2001 space odesy and you are me, and we can communicate with each other, and then become each other!?!?!

Finally, after you cleared everything up about there being more than 1 scenario that can be 'reasonably drawn', you seem to be acusing me of 'Twisting Logic' just because I can recognise that there can be more than 1 scenario???
???

You have either
1) Forgotten to take your meds
or
2) Taken too many of your meds.

1st off:
Please show me where the plane has a "Jet" engine in the OP?
2nd
Please show me where the plane has "wheels" in the op?
3rd
Basically what you have said is that an 'air powered vehicle' (as opposed to a wheel driven vehicle), in a body of water, will NOT be affected by currents.
So that means that YOU BELIEVE that a SAILBOAT while under sail power only, will NOT be affected by water currents? But as SOON as he starts the propellor spinning, the currents will then affect the boat.

You have alot of reading to do....470 pages....see you soon!

The last time I addressed your intellect I was awarded a 20% warning by moderators. I stand by that opinion, although, unfortunately it has since been removed.

To describe you as “stupid” does a disservice to the word. There are threads on this forum concerning various theories on evolution that your mere existence seems to challenge.

Your interpretation of the scenario is not logical. That is no surprise.
jeff saunders
People.

This is a pointless and stupid forum topic.

Put an airplane on a conveyor belt if you want to it doesn't matter.

What makes a plane fly is wind speed period, full stop, end of discussion.

Move the air past the plane or the plane through the air doesn't matter.

Turn the engines on or leave them off doesn't matter.

Spin the wheels or not doesn't matter.

Just move the plane through the air or the air over the plan. When it reaches a certain velocity the air moving over the wing and under the wing has the affect of creating lift and when this lift is greater than the weight of the plane it will lift off the ground.

There, nothing more to it - no mystery involved.

jeff
egnorant
The question states that the plane moves in one direction and the belt in the opposite direction.

I wish to ask ATL5P to clarify a point for me.

Please define the direction the plane is moving.

With this info we can determine the direction of the belt.

Bruce
Atl5p
QUOTE (egnorant+Feb 21 2007, 01:51 AM)
The question states that the plane moves in one direction and the belt in the opposite direction.

I wish to ask ATL5P to clarify a point for me.

Please define the direction the plane is moving.

With this info we can determine the direction of the belt.

Bruce

Hey, that's easy! All I have to do is look at the OP:

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

Hope that clears things up for you!!!

Bruce, the question is intentionally vague...the OP does NOT specify a 'direction' as in 'N, S, E, W'.

And more importantly, it does NOT specify what the plane moves in RELATION TO.

My opinion is that the above quote is to establish 'Orientation' of the plane in relation to the treadbelt. The plane is pointed "Forward" on a treadbelt, and the treadbelt is a 'normal' treadbelt in that it spins in the "Opposite" direction from a "Normal" orientation of something standing on it's belt.

The "Movement", I believe, is in relation to the surface the plane is standing on...the treadbelt. There is a 'point' on the surface of the treadbelt...the plane "Moves" away from this point.

Again, go to the gym and 'run' on a treadbelt, and set that treadbelt to 'match your speed, opposite'. Set the speed to 10mph. Someone walks in and asks 'How fast you running?'...you say '10mph' even though you are not 'moving' in relation to that person...you are 'moving' at 10mph in relation to the treadbelt.

Or another example....do earthlings often use the phrase "the sun/moon moves across the sky", or "when the sun sets, we can go home from the fields".

Does the sun actually "MOVE" across the sky? Does the sun actually 'Set'? No it dosn't. We say the sun "Moves" because we are standing on the earth.

We say the plane at 0 IAS 'moves' or 'has speed' because it is standing on the treadbelt....you need to get INSIDE the plane, bud! Watch that centerline blur past...yeah, you have speed over the treadbelt's surface.
yor_on
"Will the plane take off or not? Will it be able to run up and take off?"

What you are saing is that it doesnt have any motion at all.?
So, No way :)

Offcourse, if it's a VTOL ohhhhh yeeees. Up and Away....

Are u that sly?
Atl5p
QUOTE (Derek1148+Feb 20 2007, 08:54 PM)
The last time I addressed your intellect I was awarded a 20% warning by moderators. I stand by that opinion, although, unfortunately it has since been removed.

To describe you as “stupid” does a disservice to the word. There are threads on this forum concerning various theories on evolution that your mere existence seems to challenge.

Your interpretation of the scenario is not logical. That is no surprise.

Gee Derik...that's funny...because I though you had JUST SAID this:

QUOTE
What I was attempting to demonstrate to you was that your interpretation of the scenario was not the only one that can be reasonably drawn.

So, first you say that my interpretation was one which could be 'reasonably drawn'....and now you have reduced yourself to calling me 'stupid' and you are also questioning the fact that I have evolved along with the rest of the human species....hmmm that's very interesting.

First you try to 'demontrate' that more than one interpretation can exist....and NOW you are saying that yours and ONLY your inturpretation can exist.

Tell you what....why don't you have another 'ding' on me!

Upisoft
QUOTE (Atl5p+Feb 21 2007, 09:48 PM)
And more importantly, it does NOT specify what the plane moves in RELATION TO.

My opinion is that the above quote is to establish 'Orientation' of the plane in relation to the treadbelt.  The plane is pointed "Forward" on a treadbelt, and the treadbelt is a 'normal' treadbelt in that it spins in the "Opposite" direction from a "Normal" orientation of something standing on it's belt.

The "Movement", I believe, is in relation to the surface the plane is standing on...the treadbelt.  There is a 'point' on the surface of the treadbelt...the plane "Moves" away from this point.

OK. You've established a coordinate system with beginning at that fixed to the treadbelt point. Can the plane move in one direction in that coordinate system? Yes, it can. Can the treadbelt move in opposite direction in that same coordinate system? No, it can't move at all, because the coordinate system is fixed to the treadbelt. So, this coordinate system you've chosen doesn't satisfy the conditions.

Pick another coordinate system and try again. After several attempts you'll probably understand that you'll need a coordinate system that is not attached to the treadbelt neither to the plane. Coordinate system attached to the ground is a good choice.

Derek1148
QUOTE (Atl5p+Feb 21 2007, 08:42 PM)
So, first you say that my interpretation was one which could be 'reasonably drawn'....and now you have reduced yourself to calling me 'stupid' and you are also questioning the fact that I have evolved along with the rest of the human species....hmmm that's very interesting.

I stand corrected. I did not mean to imply that your interpretation could be reasonably drawn.
Atl5p
QUOTE (Upisoft+Feb 21 2007, 03:51 PM)
OK. You've established a coordinate system with beginning at that fixed to the treadbelt point. Can the plane move in one direction in that coordinate system? Yes, it can. Can the treadbelt move in opposite direction in that same coordinate system? No, it can't move at all, because the coordinate system is fixed to the treadbelt. So, this coordinate system you've chosen doesn't satisfy the conditions.

Pick another coordinate system and try again. After several attempts you'll probably understand that you'll need a coordinate system that is not attached to the treadbelt neither to the plane. Coordinate system attached to the ground is a good choice.

Multiple reference points are required due to the fact that a treadbelt is involved. Does that not make any sence to you at all?

Get on a treadbelt, begin moving and then set the treadbelt to match your speed exactly, except in the opposite direction. What you end up with is a 'footspeed' of 10mph (or whatever) and the treadbelt speed is 10mph. Some joker comes in and asks you 'how fast you running'? and you reply "10mph, joker". If you had wings, you would not fly.

Or, if you want to use the 'same' reference point, you can define the reference point of both the plane and the treadbelt as:

"The surface upon which the object is standing"

Plane is standing on the treadbelt...it's speed is reletive to the treadbelt.

The treadbelt machine itself is on the ground...it's speed is reletive to the ground.

Of course, that is my 'opinion'....again, the OP NEVER SPECIFIES which or what. That's kinda the point of the question.
GET IT NOW?
Grumpy
Atl5p

The reference point MUST be one which remains stationary in relation to both the plane and the belt or the conditions of the OP cannot be met.(equal speeds, opposite directions

It really makes little difference, the aircraft will move forward because there is nothing the belt can do to stop it. The plane simply ignores the bleating of Atl5p(and any movement of the belt) and continues it's takeoff run, lifting off when it's airspeed is sufficient, leaving anyone who says it can not take off with their mouth open catching flys.(not a flattering picture, but an apt one)

Grumpy
Derek1148
QUOTE (Atl5p+Feb 21 2007, 09:23 PM)
Multiple reference points are required due to the fact that a treadbelt is involved. Does that not make any sence to you at all?

Get on a treadbelt, begin moving and then set the treadbelt to match your speed exactly, except in the opposite direction. What you end up with is a 'footspeed' of 10mph (or whatever) and the treadbelt speed is 10mph. Some joker comes in and asks you 'how fast you running'? and you reply "10mph, joker". If you had wings, you would not fly.

Or, if you want to use the 'same' reference point, you can define the reference point of both the plane and the treadbelt as:

"The surface upon which the object is standing"

Plane is standing on the treadbelt...it's speed is reletive to the treadbelt.

The treadbelt machine itself is on the ground...it's speed is reletive to the ground.

Of course, that is my 'opinion'....again, the OP NEVER SPECIFIES which or what. That's kinda the point of the question.
GET IT NOW?

Brilliant.
Upisoft
QUOTE (Atl5p+Feb 22 2007, 12:23 AM)
Multiple reference points are required due to the fact that a treadbelt is involved.  Does that not make any sence to you at all?

Yes, it makes sense. However OP requires "opposite direction" for one of the movements. Unfortunately you can't define "opposite direction" when speed vectors involved rest in independent coordinate systems. And indeed the plane is not fixed to the treadbelt, it can move independently.

QUOTE (Atl5p+Feb 22 2007, 12:23 AM)
Get on a treadbelt, begin moving and then set the treadbelt to match your speed exactly, except in the opposite direction.  What you end up with is a 'footspeed' of 10mph (or whatever) and the treadbelt speed is 10mph.  Some joker comes in and asks you 'how fast you running'? and you reply "10mph, joker".  If you had wings, you would not fly.

OK, I'm on the treadbelt. And suddenly I decide to turn 180 degrees. If I continue to run forward I'll pretty soon will drop out of the treadbelt, so I have to change my direction and start running backwards. Why now "opposite direction" means running backwards? The answer is because I've chosen wrong coordinate system.

QUOTE (Atl5p+Feb 22 2007, 12:23 AM)

Or, if you want to use the 'same' reference point, you can define the reference point of both the plane and the treadbelt as:

"The surface upon which the object is standing"

Plane is standing on the treadbelt...it's speed is reletive to the treadbelt.

The treadbelt machine itself is on the ground...it's speed is reletive to the ground.

And that gets you in trouble described above... You just don't have meaningfull definition of "opposite direction".
Precursor562
Wow I can't believe this thread is still going. After much thought the problem is that people are putting too much thought into it.

For a plane to take off it must move forward in relation to the very thing it "pushes" against. It's a simple matter of equal and opposite action/reaction. In order for the plane to move forward it mush apply a force in the other direction. In this case the air. The plane produces thrust which is essentially a push off of the air. The plane begins to move forward but the belt begins to move in the opposite direction at the same speed. Since the wheels of a plane are free to spin the plane will accelerate as per normal and will take off as per normal with only one difference. The wheels of the plane will be turning at twice the speed as they normally would. Why? Because the speed of the wheels is the sum of both the speed of the plane and the speed of the belt.
Atl5p
QUOTE (Grumpy+Feb 21 2007, 05:38 PM)
Atl5p

The reference point MUST be one which remains stationary in relation to both the plane and the belt or the conditions of the OP cannot be met.(equal speeds, opposite directions

It really makes little difference, the aircraft will move forward because there is nothing the belt can do to stop it. The plane simply ignores the bleating of Atl5p(and any movement of the belt) and continues it's takeoff run, lifting off when it's airspeed is sufficient, leaving anyone who says it can not take off with their mouth open catching flys.(not a flattering picture, but an apt one)

Grumpy

'stationary in relation to both the plane and the belt ' -Grumpy

then how are either the plane or belt able to 'move'? 'Cause if either the plane OR the belt 'moves', they will cease to be 'stationary in relation to the reference point', thus the reference point will no longer be 'stationary in relation to both the plane and the belt ' -Grumpy

Try again! I think what you were TRYING to say is this:

"A plane moves though the air....is that plane moving through the air? You know, the one I just TOLD you WAS moving through the air?"

Grumpy...read this carefully....the inclusion of a treadbelt implies that 2 reference points be used.

The treadbelt uses the ground as it's reference point (like any and every treadbelt out there), and the user of the treadbelt uses as it's reference point the surface of that same said treadbelt.

Let's do a simple experiment. Get onto a treadbelt, start running and set the treadbelt to 10mph.
Question: How fast are you moving? What is your speed?

A- 10mph
B- 0mph
C- None of the above

(Answer: C - None of the above)
Why? It could be said that the question does not specify 'in relation to what'. It COULD mean to say 'What is your speed in relation to the sun?' OR 'What is your speed in relation to the Moon?"

Look, by very definition...if ANY object is "Moving" on a treadbelt, and that same treadbelt is "Matching Speed in Opposite Direction" then that object does NOT have ANY IAS!!!!! Unless, that is, if someone turns on the fan in the exercise room...THEN you will have IAS! But still no speed over the earth.

Whatever happened to your 'Operation' and 'Navigation' arguments...I was having so much fun laughing at that!!! HAHAHAHA....hey, I can still manage a laugh out of that! Cool!
Atl5p
QUOTE (Upisoft+Feb 21 2007, 06:02 PM)
Yes, it makes sense. However OP requires "opposite direction" for one of the movements. Unfortunately you can't define "opposite direction" when speed vectors involved rest in independent coordinate systems. And indeed the plane is not fixed to the treadbelt, it can move independently.

OK, I'm on the treadbelt. And suddenly I decide to turn 180 degrees. If I continue to run forward I'll pretty soon will drop out of the treadbelt, so I have to change my direction and start running backwards. Why now "opposite direction" means running backwards? The answer is because I've chosen wrong coordinate system.

And that gets you in trouble described above... You just don't have meaningfull definition of "opposite direction".

1) you are confusing ‘Movement’ with ‘Speed’ in the OP. The ‘Moves in Opposite Directions’ is to establish orientation of both plane and treadbelt directions. That is when ‘Speed’ comes into play, with the 2 points of reference. Again, you MOVE in one direction and the treadbelt MOVES in the opposite direction. You set the treadbelt to MATCH your SPEED over the surface of the treadbelt. You then have no IAS, period.

2) HUH?!?!

3) Opposite direction means ‘The other way’. Satisfied?

Look, I agree that a plane moving through the air can produce lift.

But this question is obviously asking us "Can a treadbelt prevent a plane from taking off" and the answer to that is "yes".
Grumpy
Atl5p

QUOTE
.the inclusion of a treadbelt implies that 2 reference points be used.

What an incredibly stupid thing to state!!! Since the belt is one of the things that must move IT CANNOT BE A REFERENCE POINT TO MEASURE THAT MOVEMENT.

QUOTE (->
 QUOTE .the inclusion of a treadbelt implies that 2 reference points be used.

What an incredibly stupid thing to state!!! Since the belt is one of the things that must move IT CANNOT BE A REFERENCE POINT TO MEASURE THAT MOVEMENT.

Let's do a simple experiment. Get onto a treadbelt, start running and set the treadbelt to 10mph.
Question: How fast are you moving? What is your speed?

What a goofy question!!! I am not an airplane, my motivating force is not applied to the air. You example has nothing to say about the problem at hand(the same would apply for an auto on a tread belt or a motor boat in a river). People, cars and boats apply their power to the ground or water, it makes a great deal of difference to them if that ground or water is moving. An airplane applies it's motive power to the air, it really makes no difference if the ground (or water for seaplanes) is moving.

The question in the OP asks can the plane take off, or, inversely, can the belt stop the plane from accelerating to takeoff speed. The fact is that the belt has NO WAY of influencing the speed of the aircraft through the air(no matter how you measure that speed). NO INFLUENCE=NO EFFECT, the belt might as well not be there, as far as the airplane is concerned.

QUOTE
But this question is obviously asking us "Can a treadbelt prevent a plane from taking off" and the answer to that is "yes".

Oh yeah??? HOW??? How does the belt physically restrain a powerful aircraft from moving??? What is the physical process that couples the movement of the belt to the movement of the plane through the air???(please don't say the wheels, no one is that stupid) If the plane flies just above stall speed low over the belt(even with it's wheels barely touching the belt) will movement of the belt cause it to stall??? If I fly at 100 mph very low over the belt(going the other direction at 100) what effect will it have on the speed of the airplane???

Are you finally realizing just how stupid your arguement is???

Grumpy
Precursor562
QUOTE
Oh yeah??? HOW??? How does the belt physically restrain a powerful aircraft from moving??? What is the physical process that couples the movement of the belt to the movement of the plane through the air???(please don't say the wheels, no one is that stupid) If the plane flies just above stall speed low over the belt(even with it's wheels barely touching the belt) will movement of the belt cause it to stall??? If I fly at 100 mph very low over the belt(going the other direction at 100) what effect will it have on the speed of the airplane???

I believe a better question would be how the belt can prevent the plane from accelerating to take off speeds when the only thing the belt would be in contact with are the planes wheels? Wheels which are free to turn.

Upisoft
QUOTE (Atl5p+Feb 22 2007, 02:44 AM)
1) you are confusing ‘Movement’ with ‘Speed’ in the OP.

So there can be movement without speed, or the "movement vector" and the speed vector can point somehow in different directions? Please, define what is "Movement" then and how it is connected with "Speed", if there is such connection.

QUOTE (Atl5p+Feb 22 2007, 02:44 AM)

The ‘Moves in Opposite Directions’ is to establish orientation of both plane and treadbelt directions.

To establish orientation you need common coordinate system. And because it's said that both the treadbelt and the plane move, it can't be fixed to the treadbelt nor to the plane. As I said, the ground should do.

QUOTE (Atl5p+Feb 22 2007, 02:44 AM)

2) HUH?!?!

You have problems with vectors and independently moving coordinate systems? Studding some math and physics should help.

QUOTE (Atl5p+Feb 22 2007, 02:44 AM)

3) Opposite direction means ‘The other way’.  Satisfied?

Relative to what?

QUOTE (Atl5p+Feb 22 2007, 02:44 AM)

Look, I agree that a plane moving through the air can produce lift.

But this question is obviously asking us "Can a treadbelt prevent a plane from taking off" and the answer to that is "yes".

And what force shall prevent the mighty jet engines pushing the plane through the air?

OK. Let me ask the question in other way.
1) We look at the plane in a coordinate system fixed to ground. At the beginning the plane is not moving relative to ground.
2) Engines are running.
3) As result of 2) there is force pointing forward.
4) To prevent plane from moving there should be force equal by magnitude but in opposite direction to nullify force from 3).

So where that force will come from?
Derek1148
QUOTE (Grumpy+Feb 22 2007, 12:33 AM)
no one is that stupid

The above statement is probably the only part of your post that is incorrect.
jeff saunders
I cannot really believe that alt and others still don't understand the basic physics.

AGAIN: the belt speed is irrelevant to flight. the ground speed is irrelevant to flight. We are not talking about cars or trucks but planes.

What makes a plane fly? LIFT I will say it again planes fly because of LIFT so why the going on about kilojoules of force applied to a conveyor when it is completely irrelevant?

I know some of you guys must be kids with your fathers permission to contribute to these boards but this is just too to much.

I will give you an example of a plane sitting on the tarmac when a strong head wind builds up. If the plane has it's breaks on, then it will lift off the ground as soon as that wind reaches lift off velocity for that plane.

Simple you have to be able to understand that. OK the plane will change its angle of attack to the wind and will get blown backwards a little so the wind speed over the lifting surface will reduce and the plane will come down again.

But if the wind continues and the plane stays upright it will lift off again.

Does the wind care if the plane is on a treadmill? NO.

Quote
Explination with actual formula:
If the plane rolls forward 1 meter, the plane expends 836 Kjoules, and the runway expends 88 Kjoules to try to stop it by "moving" in the opposite direction. But if the runway could somehow move fast enough to expend the same 836 Kjoules as the plane, it [/I]could[I] "hold" it in place. 836/88 = 9.5 so the runway needs to "move" 9.5 farther than the plane to prevent it from making any headway. So the "control system" needs to tune the conveyor/runway to move 9.5 times faster than the plane.
--FlyBoy
The competition is between the designers of the Treadbelt and the designers of the Airplane.

The designers of the treadbelt win if they can keep the plane from taking off. The Aircraft designers win if they can get the plane to fly.

Lets assume that the airplane designers start with a design of a plane where there such limited power that it can just barely accelerate to take off speed on a normal runway.

In such a case the increased drag a treadbelt imparts could be sufficient to keep this under powered plane on the ground.

So the aircraft designers go back to the drawing board.

But where the Treadbelt designers only have the SPEED of the treadbelt as a variable, the Aircraft designers are not so hindered by the OP.

They can use thin Titanium wheels and super low friction bearings with an added cooling system. They can bolt on a few more engines or also use friggin JATO rockets if they want, and STILL not violate the OP.

There is NO limitation on the power to weight ratio of the plane in the OP, or indeed its ability to accelerate, REGARDLESS of the drag induced by the treadbelt.

No matter how you construe the problem, the treadblelt WILL eventually reach a speed it can not exceed. There is no such limitation on the power the plane can use to exceed the drag this creates.

In this power war, the Aircraft designers will ALWAYS win.

Arthur

jacobsg
QUOTE (Atl5p+Feb 21 2007, 11:35 PM)
I think what you were TRYING to say is this:

"A plane moves though the air....is that plane moving through the air?  You know, the one I just TOLD you WAS moving through the air?"

I think what you were TRYING to say is this:

"A plane [doesn't] move[s] though the air....is that plane moving through the air? You know, the one I just TOLD you WAS [NOT] moving through the air?"
Atl5p
QUOTE (adoucette+Feb 22 2007, 10:22 AM)
The competition is between the designers of the Treadbelt and the designers of the Airplane.

The designers of the treadbelt win if they can keep the plane from taking off. The Aircraft designers win if they can get the plane to fly.

Lets assume that the airplane designers start with a design of a plane where there such limited power that it can just barely accelerate to take off speed on a normal runway.

In such a case the increased drag a treadbelt imparts could be sufficient to keep this under powered plane on the ground.

So the aircraft designers go back to the drawing board.

But where the Treadbelt designers only have the SPEED of the treadbelt as a variable, the Aircraft designers are not so hindered by the OP.

They can use thin Titanium wheels and super low friction bearings with an added cooling system. They can bolt on a few more engines or also use friggin JATO rockets if they want, and STILL not violate the OP.

There is NO limitation on the power to weight ratio of the plane in the OP, or indeed its ability to accelerate, REGARDLESS of the drag induced by the treadbelt.

No matter how you construe the problem, the treadblelt WILL eventually reach a speed it can not exceed. There is no such limitation on the power the plane can use to exceed the drag this creates.

In this power war, the Aircraft designers will ALWAYS win.

Arthur

Ahhh yes...the old standby...goes something like this:

See what you've done? You've given the plane unlimited power, but you've then LIMITED the power of the treadbelt....not really fair is it?

Try this one on for size:
"My daddy's gonna give me REALLY STICKY treadbelt surface along with a nuke powered motor from outer space."

Now the treadbelt wins....unto infinity...no take backs, I called it!
I didn't limit the power to the treadbelt, use ALL the power you want, its physics that ultimately limits the speed though.

You can't make the treadbelt STICKY because the OP defined it as "runway that moves" and runways aren't sticky.

The Airplane designers will ALWAYS win this contest.

Arthur

Atl5p
QUOTE (Precursor562+Feb 21 2007, 07:59 PM)

I believe a better question would be how the belt can prevent the plane from accelerating to take off speeds when the only thing the belt would be in contact with are the planes wheels?  Wheels which are free to turn.

First of all, the OP never says the plane has tires...but I'll play devils advocate for a moment.

There IS FRICTION from the tires.

If you put a wheeled vehicle on a treadbelt and attatched a force scale to it, and then take measurements at various speeds, you will find the force meter reads a higher level of force at the higher treadbelt speeds.

If this was not true, then this would happen:
You drive down a flat road at 20mph with a 20mph tail wind (0 IAS to you in the car), put the car in neutral and coast....your car would never stop.

And we all know that the above would never happen. That's because the tires have friction, and the tires will slow the car to a stop.

So, the faster the treadbelt spins, the greater the opposing force.

When the treadbelt matches the plane's speed over the treadbelt, then the treadbelt will spin faster and faster until the opposing force equals the plane's static thrust.

Do you know anything about static thrust, RPM, Prop size and pitch speed?

If the plane has a very small diameter prop, but has a high 'pitch', then the plane basically has 'low torque' and 'high speed'. So it accelerates slow, but as it gets IAS, it is able to keep going faster and faster.
This type of setup will result in a low 'static thrust' value, meaning 'not much power when in 0 IAS'. No getup and go. This would be the easiest setup for a treadbelt to hold a plane at 0IAS, and yet that plane would still take off from a normal runway.

If you think tires will let you travel 'for free' without friction, then you are wrong. That friction coeficcent factor may not change, it is MULTIPLIED by the speed, not added. That means that increasing the speed will increase the overall (opposing) force. Is this what you are not understanding? I am a patient person.
Atl5p
QUOTE (adoucette+Feb 22 2007, 12:27 PM)
I didn't limit the power to the treadbelt, use ALL the power you want, its physics that ultimately limits the speed though.

You can't make the treadbelt STICKY because the OP defined it as "runway that moves" and runways aren't sticky.

The Airplane designers will ALWAYS win this contest.

Arthur

Either way, you've made it to where the treadbelt cannot fulfill the OP; the treadbelt must match the palne's speed, where the palne's speed is defined as it's speed over the surface of the runway (ie wheelspeed).

The OP requires that the treadbelt be able to keep up with this speed.

You have violated the OP. You cannot do that.
QUOTE (Atl5p+Feb 22 2007, 12:35 PM)
Either way, you've made it to where the treadbelt cannot fulfill the OP; the treadbelt must match the palne's speed, where the palne's speed is defined as it's speed over the surface of the runway (ie wheelspeed).

The OP requires that the treadbelt be able to keep up with this speed.

You have violated the OP.  You cannot do that.

Nope, now you are just into an argument about what the OP meant.

The OP never mentions "wheelspeed", and the argument about frame of reference can't be answered since the OP does not specify a frame of reference.

What is true though is there ARE physical limitations to the speed of the treadbelt while there are no such limitations to the RELATIVE speed of the aircraft.

The Airplane designers will ALWAYS win.

Arthur
yor_on
Hey, I've got it. At last i understand physics ;).
F*** that thread mill F*** that plane. The universe are expanding/moving right ;)
the galaxies are also Spinning and moving right. So are our Solar system.
Yes yes yes, I've had a vision.
I will just pluck some feathers of some poor bird over there, then i will turn myself in the appropriate direction with my arms outstretched where the collected forces off all those motions just will lift me out of this discussion. How about that?
yor_on
Nope.

Didn't work.
TheEnd
Interesting tid bits

Total posts on this thread 7074 (Feb 22, 07)

Posts on this thread by registered atl5p: 902 (~439 days ago)
Posts on this thread by unregistered atl5p: ~100
Posts on this thread by guest (stealth) atl5p: unknown, presumed > 0.
Percentage of total posts from atl5p on this thread > 14%

Current page: 472.

It's amazing how one stubborn individual can drag others along for such a long ride.

Troll Extraordinaire!

TEOTW(AWKI)
Upisoft
QUOTE (TheEnd+Feb 22 2007, 10:18 PM)
Interesting tid bits

Total posts on this thread 7074 (Feb 22, 07)

Posts on this thread by registered atl5p: 902 (~439 days ago)
Posts on this thread by unregistered atl5p: ~100
Posts on this thread by guest (stealth) atl5p: unknown, presumed > 0.
Percentage of total posts from atl5p on this thread > 14%

Current page: 472.

It's amazing how one stubborn individual can drag others along for such a long ride.

Troll Extraordinaire!

TEOTW(AWKI)

Yep. He deserves a monument!
I have a basic idea how it must look like... A treadbelt reaching through the space to stop a plane from taking off...
Grumpy
Upisoft

QUOTE
Yep. He deserves a monument!
I have a basic idea how it must look like... A treadbelt reaching through the space to stop a plane from taking off... smile.gif

I would suggest a rock, a really, really thick rock, carved into the likeness of his head.

ATL5p

QUOTE (->
 QUOTE Yep. He deserves a monument!I have a basic idea how it must look like... A treadbelt reaching through the space to stop a plane from taking off... smile.gif

I would suggest a rock, a really, really thick rock, carved into the likeness of his head.

ATL5p

When the treadbelt matches the plane's speed over the treadbelt, then the treadbelt will spin faster and faster until the opposing force equals the plane's static thrust.

What happened to the tread belt moving in the opposite direction AT THE SAME SPEED AS THE PLANE???(not " faster and faster", but the same speed) It is you who is violating the conditions of the OP. And since we must measure the speed of both the plane and the belt the point of reference(with which we compare the speed of both) cannot be either the belt or the plane. The OP does not say anything about matching opposing forces, but it certainly does say that the speeds of the airplane (not it's wheels) and the belt must be the same.

QUOTE
You have violated the OP. You cannot do that.

Neither can you!!!

QUOTE (->
 QUOTE You have violated the OP. You cannot do that.

Neither can you!!!

If you think tires will let you travel 'for free' without friction, then you are wrong. That friction coeficcent factor may not change, it is MULTIPLIED by the speed, not added. That means that increasing the speed will increase the overall (opposing) force. Is this what you are not understanding? I am a patient person.

Ah, but the speed of the treadmill is limited to the speed of the airplane, and at that speed friction is negligable.

Besides, I mounted hovercraft pads on my plane, the friction of the wheels is now gone(hovercraft have ZERO friction, no matter what the speed or direction)

It even takes off on water(and doesn't care what direction or speed it is going in either)

How are you going to stop that???

Grumpy
Precursor562
QUOTE
First of all, the OP never says the plane has tires...but I'll play devils advocate for a moment.

Last I checked any plane that is on solid ground (not water or snow) has wheels.

QUOTE (->
 QUOTE First of all, the OP never says the plane has tires...but I'll play devils advocate for a moment.

Last I checked any plane that is on solid ground (not water or snow) has wheels.

There IS FRICTION from the tires.

If you put a wheeled vehicle on a tread belt and attached a force scale to it, and then take measurements at various speeds, you will find the force meter reads a higher level of force at the higher tread belt speeds.

If this was not true, then this would happen:
You drive down a flat road at 20mph with a 20mph tail wind (0 IAS to you in the car), put the car in neutral and coast....your car would never stop.

First off the friction in the wheels of the plane would be quite small. Hell you could spin the wheels by hand on any plane used today (even the space shuttle) provided the wheels were off the ground. No this isn't to reduce the friction by taking the weight off of the wheels, this is just so that your only spinning the tires and not trying to move the multi ton craft. Yes there is some but in order for the belt to generate enough resistance to motion within the wheels the belt would have to be moving at much faster speeds than the plane would be in the opposite direction. This of course goes against the original question.

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

The question is:

Will the plane take off or not? Will it be able to run up and take off?

So let's say that the plane is on the belt runway and painted on the belt directly under the plane is a red circle. At the end of the belt runway is the air traffic control tower but this tower is not on the belt and is on solid (stationary) ground. The tower is at the end of the runway that the plane is facing. The plane must move through the air (air that is stationary just to keep it simple) at 100 mph in order to achieve the lift needed for take off. So the plane must push against the air (thrust) and not the runway to move forward at this speed. So now the distance between the plane and the tower is getting smaller at a rate increasing from 0 to 100 mph. The treadmill will move in the opposite direction at the same speed resulting in the distance between the red circle and the tower increasing at the same increasing rate 0 to 100 mph. Will this speed create enough friction within the wheels to generate enough resistance to turn to counter the force of thrust produce by the plane? No. Will the engine have to work harder sure but only a tiny bit. Since the OP refers to just "A plane" I would hope they are referring to any plane you would find at any airport (which have wheels the last time I looked) where the engine is capable of producing enough thrust for the plane to achieve speeds greater than takeoff speed. Also by the statement...

QUOTE (->
 QUOTE A plane is standing on runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in opposite direction).The question is:Will the plane take off or not? Will it be able to run up and take off?

So let's say that the plane is on the belt runway and painted on the belt directly under the plane is a red circle. At the end of the belt runway is the air traffic control tower but this tower is not on the belt and is on solid (stationary) ground. The tower is at the end of the runway that the plane is facing. The plane must move through the air (air that is stationary just to keep it simple) at 100 mph in order to achieve the lift needed for take off. So the plane must push against the air (thrust) and not the runway to move forward at this speed. So now the distance between the plane and the tower is getting smaller at a rate increasing from 0 to 100 mph. The treadmill will move in the opposite direction at the same speed resulting in the distance between the red circle and the tower increasing at the same increasing rate 0 to 100 mph. Will this speed create enough friction within the wheels to generate enough resistance to turn to counter the force of thrust produce by the plane? No. Will the engine have to work harder sure but only a tiny bit. Since the OP refers to just "A plane" I would hope they are referring to any plane you would find at any airport (which have wheels the last time I looked) where the engine is capable of producing enough thrust for the plane to achieve speeds greater than takeoff speed. Also by the statement...

This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in opposite direction).

They say "the plane speed" not thrust or wheel speed but the speed of the plane's physical movement. Such physical movement is determined by either comparing the position of the plane to a fixed point (I used a control tower in the example) in which case you would have to use the same reference point for the the belt as I did in the example or you can look at the increasing distance between the plane's new location and starting location while doing the same for a point on the belt.

Since the speed of the belt would have to be very fast (going against the OP) to generate the resistance due to friction within the wheels of a craft whose wheels could be spun by a person (and stay spinning for a few seconds on its own under its own momentum) then it would be best to just overlook such facts and keep it simple. As the expression goes "Keep it simple stupid"

So I ask again can the belt hold back a plane from reaching take off speeds when the belt is only in contact with the plane's wheels and such wheels can spin freely?

No it can not. Also if you take a toy car and place it on a treadmill and connect the car to a scale (the scale keeps the treadmill from taking the car for a ride) once you turn on the treadmill you will get a reading on the scale due to the wheels resistance to turn. I agree with you on that but say you get a reading of 5 lbs at 50 mph you also won't get a reading of 10 lbs at 100 mph but you will actually get a reading of less that 10 lbs and not greater than. This is not to say it will stop at one point because it won't. The friction and therefore the resistance to turn will always increase as rate of spin increases but the rate at which this resistance increases slows down as rate of spin continues to increase at a constant rate. With the plane the friction would generate enough heat to create critical failure long before enough resistance is reached to prevent the plane from taking off.

The amount of heat generated depends on the friction. The faster two parts rub together the more friction and it is this friction that not only produces heat but creates the resistance to turn any faster. However the rate at which the friction increases as speed increase is greater than the ever slowing rate at which the resistance to turn any faster increases. The reason for this is energy loss in the form of heat. The rate at which heat is generated by the friction as a result of the increase in speed is increasingly greater than the rate at which the friction increases.
Atl5p
QUOTE (Grumpy+Feb 22 2007, 05:52 PM)
Upisoft

I would suggest a rock, a really, really thick rock, carved into the likeness of his head.

ATL5p

What happened to the tread belt moving in the opposite direction AT THE SAME SPEED AS THE PLANE???(not " faster and faster", but the same speed) It is you who is violating the conditions of the OP. And since we must measure the speed of both the plane and the belt the point of reference(with which we compare the speed of both) cannot be either the belt or the plane. The OP does not say anything about matching opposing forces, but it certainly does say that the speeds of the airplane (not it's wheels) and the belt must be the same.

Neither can you!!!

Ah, but the speed of the treadmill is limited to the speed of the airplane, and at that speed friction is negligable.

Besides, I mounted hovercraft pads on my plane, the friction of the wheels is now gone(hovercraft have ZERO friction, no matter what the speed or direction)

It even takes off on water(and doesn't care what direction or speed it is going in either)

How are you going to stop that???

Grumpy

the treadbelt spins faster and faster UNTIL the speed of the treadbelt MATCHES the speed of the plane*

*where the speed of the plane is defined as it's speed over the surface of the treadbelt.

The obvious purpose of the question is to ask 'can a treadbelt prevent a plane from flying', the plane is ON the treadbelt, so the "Plane's Speed" is reletive to the surface upon which it is traveling.

Kinda like when you ride down the highway at 17,000mph. You think you're speed is 17,000mph, right? But what if an 'outside observer' is in orbit directly above you. He would say 'Hey, you're not moving at all'. That outside observer is YOU. And I'm in the car, and I'm telling you, I am going 17,000mph!! Why? Because it's in relation to the surface upon which I am traveling. DUH!

I find it amusing that you seem to be the only one left who believes that there is no friction coming from the tires....

Oh, and your hovercraft, sure...there is no direct contact to the surface of the treadbelt....I think it becomes much harder for the treadbelt to hold that vehicle at 0 IAS...but I believe that the FlyBoys are thinking that a wheeled plane behaves exactly like your hovercraft, and that is incorrect.
gmilam
QUOTE (TheEnd+Feb 22 2007, 01:18 PM)
Interesting tid bits

Total posts on this thread 7074 (Feb 22, 07)

Posts on this thread by registered atl5p: 902 (~439 days ago)
Posts on this thread by unregistered atl5p: ~100
Posts on this thread by guest (stealth) atl5p: unknown, presumed > 0.
Percentage of total posts from atl5p on this thread > 14%

Current page: 472.

It's amazing how one stubborn individual can drag others along for such a long ride.

Troll Extraordinaire!

TEOTW(AWKI)

Yeah, ATL5P was humorous for a while. Now he's just annoying.

The phrase "Thick as a Brick" comes to mind.
rethinker
edit
Derek1148
QUOTE (gmilam+Feb 22 2007, 11:41 PM)
The phrase "Thick as a Brick" comes to mind.

Hey,
Come on, let's be fair now. Jethro Tull is far too talented to be associated in any way with ATL5P.
Atl5p
QUOTE (Precursor562+Feb 22 2007, 06:04 PM)

Last I checked any plane that is on solid ground (not water or snow) has wheels.

First off the friction in the wheels of the plane would be quite small. Hell you could spin the wheels by hand on any plane used today (even the space shuttle) provided the wheels were off the ground. No this isn't to reduce the friction by taking the weight off of the wheels, this is just so that your only spinning the tires and not trying to move the multi ton craft. Yes there is some but in order for the belt to generate enough resistance to motion within the wheels the belt would have to be moving at much faster speeds than the plane would be in the opposite direction. This of course goes against the original question.

So let's say that the plane is on the belt runway and painted on the belt directly under the plane is a red circle. At the end of the belt runway is the air traffic control tower but this tower is not on the belt and is on solid (stationary) ground. The tower is at the end of the runway that the plane is facing. The plane must move through the air (air that is stationary just to keep it simple) at 100 mph in order to achieve the lift needed for take off. So the plane must push against the air (thrust) and not the runway to move forward at this speed. So now the distance between the plane and the tower is getting smaller at a rate increasing from 0 to 100 mph. The treadmill will move in the opposite direction at the same speed resulting in the distance between the red circle and the tower increasing at the same increasing rate 0 to 100 mph. Will this speed create enough friction within the wheels to generate enough resistance to turn to counter the force of thrust produce by the plane? No. Will the engine have to work harder sure but only a tiny bit. Since the OP refers to just "A plane" I would hope they are referring to any plane you would find at any airport (which have wheels the last time I looked) where the engine is capable of producing enough thrust for the plane to achieve speeds greater than takeoff speed. Also by the statement...

They say "the plane speed" not thrust or wheel speed but the speed of the plane's physical movement. Such physical movement is determined by either comparing the position of the plane to a fixed point (I used a control tower in the example) in which case you would have to use the same reference point for the the belt as I did in the example or you can look at the increasing distance between the plane's new location and starting location while doing the same for a point on the belt.

Since the speed of the belt would have to be very fast (going against the OP) to generate the resistance due to friction within the wheels of a craft whose wheels could be spun by a person (and stay spinning for a few seconds on its own under its own momentum) then it would be best to just overlook such facts and keep it simple. As the expression goes "Keep it simple stupid"

So I ask again can the belt hold back a plane from reaching take off speeds when the belt is only in contact with the plane's wheels and such wheels can spin freely?

No it can not. Also if you take a toy car and place it on a treadmill and connect the car to a scale (the scale keeps the treadmill from taking the car for a ride) once you turn on the treadmill you will get a reading on the scale due to the wheels resistance to turn. I agree with you on that but say you get a reading of 5 lbs at 50 mph you also won't get a reading of 10 lbs at 100 mph but you will actually get a reading of less that 10 lbs and not greater than. This is not to say it will stop at one point because it won't. The friction and therefore the resistance to turn will always increase as rate of spin increases but the rate at which this resistance increases slows down as rate of spin continues to increase at a constant rate. With the plane the friction would generate enough heat to create critical failure long before enough resistance is reached to prevent the plane from taking off.

The amount of heat generated depends on the friction. The faster two parts rub together the more friction and it is this friction that not only produces heat but creates the resistance to turn any faster. However the rate at which the friction increases as speed increase is greater than the ever slowing rate at which the resistance to turn any faster increases. The reason for this is energy loss in the form of heat. The rate at which heat is generated by the friction as a result of the increase in speed is increasingly greater than the rate at which the friction increases.

Since a treadbelt is used, we MUST use 2 reference points for determining speed. You are incorrect in that point.

Speed of a ground based object is usually based on the surface upon which it is traveling.

You give an example of suspending a vehicle in the air and spinning the tires by hand. That has very little bearing on the friction I'm talking about. The friction I am talking about requires you to put the full weight of the vehicle onto those tires, squshing them so that there is a deformation in the tire where that said tire meets the road. That is where the friction is.

And if you want to blow that tire up because of the speed, then it blows up long before enough airspeed is achieved to fly.

Look...I took an airpropelled vehicle and was able to stop it with a treadbelt. The vehicle moved fine by itself on static ground. It moved fine on a static treadbelt. But at a certian beltspeed the plane had 0 IAS and at the same time, the 'wheelspeed' was exactly the same as the 'treadbelt speed'.
THEN I increased the treadbelt speed somemore, and then the plane had negetive airspeed.

If I can do that with a small plane and a normal sized treadbelt, then one could do that with a real plane and very large powerful treadbelt.

Basically it works out like this: Spin the treabelt fast enough, and it will prevent an airpowered vehicle from haveing IAS. WHEN THAT OCCURS, the vehicle's speed over the surface of the treadbelt will be EQUAL = EQUAL to the speed of the treadbelt over the surface of the ground.

But, if you want to say 'Plane speeds towards that tower over there...', then BOOM, you've just said it...Plane has airspeed....does that plane have airspeed?

Way to go, you must be the smartest lifeform in the universe! WOW!

But "Can a treadbelt prevent a plane from taking off"? Now we've got to think about it....
yor_on
As an afterthought.
Why not put wings on the thread mill and see which lifts first?
Then i could stop chasing birds
Precursor562
QUOTE
The obvious purpose of the question is to ask 'can a treadbelt prevent a plane from flying', the plane is ON the treadbelt, so the "Plane's Speed" is reletive to the surface upon which it is traveling.

There is mistake number one and 1.5. To clear up 1.5..The obvious purpose of the question is to ask 'can a treadbelt prevent a plane from flying if the belt's speed were to equal the plane's speed?

QUOTE (->
 QUOTE The obvious purpose of the question is to ask 'can a treadbelt prevent a plane from flying', the plane is ON the treadbelt, so the "Plane's Speed" is reletive to the surface upon which it is traveling.

There is mistake number one and 1.5. To clear up 1.5..The obvious purpose of the question is to ask 'can a treadbelt prevent a plane from flying if the belt's speed were to equal the plane's speed?

Kinda like when you ride down the highway at 17,000mph.

There is mistake number two.

For number one. To get the plane's speed you will need a fixed point of reference and the belt is not a fixed point since it moves. You use the fixed point of reference for comparison to get an accurate distance traveled. You can then take the distance and divide it by the time it took the plane to move that distance to get your speed. The same is done with the belt. AGAIN YOU DO NOT USE THE BELT AS A POINT OF REFERENCE SINCE IT IS MOVING AND IS BEING COMPARED TO THE PLANE'S MOTION!!!!

Truthfully you would compare it to the air since that is what the plane pushes against to move forward. So with a plane that needs to reach 100 mph in still air to get the lift required for takeoff then the plane can achieve the same lift without moving forward at all provide the plane is facing into 100 mph winds.

For number two. A car is a different story altogether. I have seen the error in my ways and to compare the plane to that of a car in any way shape or form is comparing apples to oranges. For starters a car gets its movement by pushing off the ground it sits on which is the belt in this case. Since the belt matches the speed of the the vehicle and not the speed of the vehicle's wheels Than a car too would move forward on the belt.

The difference being that the plane would move forward the same as if it were on stationary ground since at such speeds the resistance due to friction would be small enough not to consider. The car on the treadmill going forward at 100mph would have a wheel speed of 200mph (the sum of the speed of both the car and belt) and since the work of the engine goes into pushing off the ground than the work of the engine in the car going 100 mph on the belt would be the same as if it were going 200 mph on still ground. This makes for a considerable difference between the car and plane.

As for your analogy involving relative motion between a person and an observer such a thing has no relevance to the situation.
Precursor562
Now I know your full of it because I too took my radio controlled plane to my parents treadmill when I visited them on Christmas leave (ah vacation rather, I'm military so I use odd terminology) and no matter what speed I set the treadmill to (max speed was in the 20s km/h (I'm Canadian) if my memory serves me well) the plane took off forward with no visible difference between the treadmill and still ground. Take it the plane didn't fly because I need 20 to 30 feet of runway but the plane still accelerated as per normal.

I then proceeded to use a radio controlled car. I determined the speed of the car using judgment then set the treadmill to that speed where I then did some fine tuning so that when the car was trying to move at full speed forward the belt matched the speed backward and the car didn't move. I was then shown the error in this and it turned out I had set the treadmill to the speed of the wheels and not the speed of the car since the car was actually not moving. It would have been accurate had I cut the speed in half and put the car on the treadmill. Only that would have shown the speed of the treadmill equaling the speed of the car.

QUOTE
Since a treadbelt is used, we MUST use 2 reference points for determining speed. You are incorrect in that point.

You much use a fixed point when determining of just one thing. In this case it is the plane that were are determining the movement of. Just the plane, not the belt. The belt is merely matching the movement of the plane in the opposite direction and nothing more. So to determine the motion of the plane (and therefore the plane's speed when time is factored in) you much use a fixed (stationary) point of reference. Such a point can be anything (imaginary, starting position or some other stationary object such as a tower) as long as it is a fixed (stationary) point. The belt is not stationary since it is moving at the same speed as the plane in the opposite direction so it CAN NOT be used as a point of reference to measure distance traveled through space (I mean that generically and am not referring to outer space or empty voids) which true distance traveled would be. The belt need not use the same fixed reference point but could use another like a second tower or it could use its own starting point as a point of reference (not the plane's starting point but its own) but it would be better if both use a common point and such a point would have to be unrelated to either one (plane nor belt) such as a single control tower. This allows for less chance of mistake.

QUOTE (->
 QUOTE Since a treadbelt is used, we MUST use 2 reference points for determining speed. You are incorrect in that point.

You much use a fixed point when determining of just one thing. In this case it is the plane that were are determining the movement of. Just the plane, not the belt. The belt is merely matching the movement of the plane in the opposite direction and nothing more. So to determine the motion of the plane (and therefore the plane's speed when time is factored in) you much use a fixed (stationary) point of reference. Such a point can be anything (imaginary, starting position or some other stationary object such as a tower) as long as it is a fixed (stationary) point. The belt is not stationary since it is moving at the same speed as the plane in the opposite direction so it CAN NOT be used as a point of reference to measure distance traveled through space (I mean that generically and am not referring to outer space or empty voids) which true distance traveled would be. The belt need not use the same fixed reference point but could use another like a second tower or it could use its own starting point as a point of reference (not the plane's starting point but its own) but it would be better if both use a common point and such a point would have to be unrelated to either one (plane nor belt) such as a single control tower. This allows for less chance of mistake.

Speed of a ground based object is usually based on the surface upon which it is traveling.

You give an example of suspending a vehicle in the air and spinning the tires by hand. That has very little bearing on the friction I'm talking about. The friction I am talking about requires you to put the full weight of the vehicle onto those tires, squshing them so that there is a deformation in the tire where that said tire meets the road. That is where the friction is.

Yes the airplane is on the ground but I wouldn't call it a ground based object because a plane travels through flight. It pushes off the air to move forward, it uses air to lift and spend most of its travel time in the air. It is an air based object not a ground based object.

The friction you are talking about then would lessen considerably as the plane picked up speed. The friction you are talking about is molecular and is the rubber's resistance to bend out of its natural shape. The tire goes from a curve to a steeper curve (a bend) as it contacts the belt then straightens out (flattens) then bends again then unbends back to its natural state (curve). The plane receives lift the moment air passes over and under the wings and so the plane receives lift the moment it begins moving forward. This lifting force would take the weight off of the tires allowing them to return closer to their normal round position taking away the wheels resistance to turn as a result of such bending. Also to help with the tire returning to its natural state would be centrifugal force and the air pressure within the tire along with the elasticity of the tire to want to return to its natural shape.

Once the plane reaches take off speed the plane would become "weightless" and the tire will be allowed to return to its round natural shape eliminating that line of friction and therefore eliminating that line of resistance altogether. A properly inflated tire can reach considerable speeds without worry of a blow out as a direct result of such friction (structural integrity of the rubber weakens as temperature due to friction increases) since at such speeds air flow will have a cooling effect. This is also why it is important to make sure the tires on your car are properly inflated since a tire that is 'low' has more friction and generates more heat resulting in a blow out often on the highway (worst time to have a blow out).

The bearings are more likely to over heat and cease up long before the tire would blow out if properly inflated. That's when the momentum of the large mass plane would keep it moving forward for a short distance and with the tires completely ceased I wouldn't be surprised to see the tires get ripped off the plane.
egnorant
QUOTE (Atl5p+Feb 22 2007, 11:49 PM)
Speed of a ground based object is usually based on the surface upon which it is traveling.

No it is not.
I put this plane on a trailer and tow it at 50 mph.
The speed of the plane is also 50 mph.

QUOTE
But, if you want to say 'Plane speeds towards that tower over there...', then BOOM, you've just said it...Plane has airspeed....does that plane have airspeed?

And the opposite direction is..away from that tower.

Thank you for finally assigning a direction to the plane.

Bruce
egnorant
sorry..double post
Grumpy
Atl5p

QUOTE
the treadbelt spins faster and faster UNTIL the speed of the treadbelt MATCHES the speed of the plane*

*where the speed of the plane is defined as it's speed over the surface of the treadbelt.

Actually the only time they would match is when neither is moving.

QUOTE (->
 QUOTE the treadbelt spins faster and faster UNTIL the speed of the treadbelt MATCHES the speed of the plane**where the speed of the plane is defined as it's speed over the surface of the treadbelt.

Actually the only time they would match is when neither is moving.

Look...I took an airpropelled vehicle and was able to stop it with a treadbelt. The vehicle moved fine by itself on static ground. It moved fine on a static treadbelt. But at a certian beltspeed the plane had 0 IAS and at the same time, the 'wheelspeed' was exactly the same as the 'treadbelt speed'.
THEN I increased the treadbelt speed somemore, and then the plane had negetive airspeed.

That must have been some wimpy a\$\$ed plane. I know you won't even slow down any of my RC aircraft! My Tribute takes off in three feet(no wind) and then goes straight up, I'm even getting good enough to hover it for a few seconds.

QUOTE
I find it amusing that you seem to be the only one left who believes that there is no friction coming from the tires....

I, myself, have mentioned the friction of the tires as the only means the treadmill has of affecting the plane. The friction generated by the wheels is only a tiny fraction of the power of the plane and is insignificant.

QUOTE (->
 QUOTE I find it amusing that you seem to be the only one left who believes that there is no friction coming from the tires....

I, myself, have mentioned the friction of the tires as the only means the treadmill has of affecting the plane. The friction generated by the wheels is only a tiny fraction of the power of the plane and is insignificant.

Oh, and your hovercraft, sure...there is no direct contact to the surface of the treadbelt....I think it becomes much harder for the treadbelt to hold that vehicle at 0 IAS...but I believe that the FlyBoys are thinking that a wheeled plane behaves exactly like your hovercraft, and that is incorrect.

AHA!!! The lad can think. The point of the hovercraft example was to show the only effect the belt has is tire friction(on a normal plane, not the hovercraft) and that if the belt is limited to the speed of the plane the additional drag of the wheels at worst doubles, not enough to stop the plane by a long shot.

It flies.

Grumpy
Precursor562
nvm
Eric England
Has the plane run out of fuel yet?
My aircraft designer has just showed up with his latest aircraft design.

Its a Saturn V laid on its side, with three titanium wheels and a pair of large wings bolted on.

Stand back while we light this sucker off.

Like I said:

The Airplane designers ALWAYS wins.

Arthur

Atl5p
Precursor –
You said “As for your analogy involving relative motion between a person and an observer such a thing has no relevance to the situation”

You seem to have missed the entire point.

Let’s try again, on a large ship at sea. The ship is 1 mile long. It is heading north at 20mph over the bottom. The wind is heading south at 20mph. The current is going south at 5mph.
I am walking on the deck at a speed which will take me from stern to bow in 1 hour.
YOU are in a helicopter flying directly above ME as I walk.
Q: ‘What is MY SPEED?’

You in the helicopter see my speed a 0mph (relative to you).

But I see my speed as 1mph (relative to the deck).

And someone standing on the shore would see my speed as 21mph.

And someone in a powerless boat in the current would see my speed as 26mph.

Now, make the boat “Match MY SPEED”.

How fast is the boat going now?

Precursor 2 – Again I ask….do you know anything about prop diameter, prop pitch, RPM, and STATIC THRUST? Apparently not. As I’ve stated before, a plane has to go pretty slow on static ground to be able to be held at 0 IAS by a 10mph or less treadbelt. When it’s held at 0IAS on the treadbelt, it has all it’s static thrust. But then put it on static ground, and the plane’s thrust will decrease due to the artificial ‘headwind’ it creates by moving through the air. Due to static thrust, the treadbelt speed might need to be higher than you think it should, but when the plane is at 0 IAS, the speed of the plane over the treadbelt, will match EXACTLY the speed of the treadbelt.

Again, due to the treadbelt, we MUST use two reference points for speed.

Next, when the treadbelt succeeds in holding the plane at 0 IAS, duh, there is NO LIFT to take away resistance at the tires….so that whole argument just got wasted! SORRY!

Egnorant – What if I am on the trailer with the plane….and I walk from the back of the trailer to the front of the trailer at a speed of 5mph….now, what is my speed and what is the plane’s speed?
Hint – My Speed is 5mph and the plane’s speed is 0mph OVER THE SURFACE OF THE TRAILERBED.
QUOTE (Atl5p+Feb 23 2007, 12:34 PM)
do you know anything about prop diameter, prop pitch, RPM, and STATIC THRUST? Apparently not. As I’ve stated before, a plane has to go pretty slow on static ground to be able to be held at 0 IAS by a 10mph or less treadbelt. When it’s held at 0IAS on the treadbelt, it has all it’s static thrust. But then put it on static ground, and the plane’s thrust will decrease due to the artificial ‘headwind’ it creates by moving through the air. Due to static thrust, the treadbelt speed might need to be higher than you think it should, but when the plane is at 0 IAS, the speed of the plane over the treadbelt, will match EXACTLY the speed of the treadbelt.

Again, due to the treadbelt, we MUST use two reference points for speed.

Next, when the treadbelt succeeds in holding the plane at 0 IAS, duh, there is NO LIFT to take away resistance at the tires….so that whole argument just got wasted! SORRY!

Egnorant – What if I am on the trailer with the plane….and I walk from the back of the trailer to the front of the trailer at a speed of 5mph….now, what is my speed and what is the plane’s speed?
Hint – My Speed is 5mph and the plane’s speed is 0mph OVER THE SURFACE OF THE TRAILERBED.

Say that again????

Ever heard of VARIABLE PITCH props?

By the way our latest design has flaps that divert sufficient thrust to reduce the weight on the titanium tires to less than 1 gram. So while its not really a VTOL aircraft, it has an infintesimal amount of weight on its tires.

Like I said:

The airplane designer ALWAYS wins.

Arthur
Fynlcut
QUOTE (Atl5p+Feb 23 2007, 05:34 PM)
Precursor –
You said “As for your analogy involving relative motion between a person and an observer such a thing has no relevance to the situation”

You seem to have missed the entire point.

Let’s try again, on a large ship at sea.  The ship is 1 mile long.  It is heading north at 20mph over the bottom.  The wind is heading south at 20mph.  The current is going south at 5mph.
I am walking on the deck at a speed which will take me from stern to bow in 1 hour.
YOU are in a helicopter flying directly above ME as I walk.
Q: ‘What is MY SPEED?’

You in the helicopter see my speed a 0mph (relative to you).

But I see my speed as 1mph (relative to the deck).

And someone standing on the shore would see my speed as 21mph.

And someone in a powerless boat in the current would see my speed as 26mph.

Now, make the boat “Match MY SPEED”.

How fast is the boat going now?

Precursor 2 – Again I ask….do you know anything about prop diameter, prop pitch, RPM, and STATIC THRUST?  Apparently not.  As I’ve stated before, a plane has to go pretty slow on static ground to be able to be held at 0 IAS by a 10mph or less treadbelt.  When it’s held at 0IAS on the treadbelt, it has all it’s static thrust.  But then put it on static ground, and the plane’s thrust will decrease due to the artificial ‘headwind’ it creates by moving through the air.  Due to static thrust, the treadbelt speed might need to be higher than you think it should, but when the plane is at 0 IAS, the speed of the plane over the treadbelt, will match EXACTLY the speed of the treadbelt.

Again, due to the treadbelt, we MUST use two reference points for speed.

Next, when the treadbelt succeeds in holding the plane at 0 IAS, duh, there is NO LIFT to take away resistance at the tires….so that whole argument just got wasted!  SORRY!

Egnorant – What if I am on the trailer with the plane….and I walk from the back of the trailer to the front of the trailer at a speed of 5mph….now, what is my speed and what is the plane’s speed?
Hint – My Speed is 5mph and the plane’s speed is 0mph OVER THE SURFACE OF THE TRAILERBED.

The ship is moving north at 20mph, and you are walking north 1mph on the boat.

So your total speed north would be 21mph. The boat was already going 5 mph south so it needs to speed up by 16mph to match your speed in the opposite direction! see isn't that simple!

Now
You in the helicopter see my speed as 0mph (relative to you). and see the boat moving away at 42 mph and the ship at 1mph

But I see my speed as 1mph (relative to the deck). and 42 mph relative to the boat and 21 mph relative to the shore

And someone standing on the shore would see my speed as 21mph. and the boats speed as 21mph in the opposite direction, the ship at 20mph and the helicopter at 21 mph north

And someone in a powerless boat in the current would see my speed as 42 mph. Knowing they are moving south at 21mph it is easy to determin that you are moving 21 mph to the north.

DEE DEE DEE
Atl5p
QUOTE (adoucette+Feb 23 2007, 12:44 PM)
Say that again????

Ever heard of VARIABLE PITCH props?

By the way our latest design has flaps that divert sufficient thrust to reduce the weight on the titanium tires to less than 1 gram. So while its not really a VTOL aircraft, it has an infintesimal amount of weight on its tires.

Like I said:

The airplane designer ALWAYS wins.

Arthur

Yes I have heard of variable pitch props....and you point???

That's a nice plane you have there....have fun. But you seem to think this is a contest between designers, which it isn't....might make a neat thread so why don't you start one and have fun!
egnorant
QUOTE (Atl5p+Feb 23 2007, 05:34 PM)
Egnorant – What if I am on the trailer with the plane….and I walk from the back of the trailer to the front of the trailer at a speed of 5mph….now, what is my speed and what is the plane’s speed?
Hint – My Speed is 5mph and the plane’s speed is 0mph OVER THE SURFACE OF THE TRAILERBED.

Correct! Factoring in those items will give you a speed of 55 mph and the plane is still at 50 mph.

Adding the modifier "OVER THE SURFACE OF THE TRAILERBED" (belt..whatever)
Will yield different results.
The original question has no such modifiers.

Bruce
QUOTE (Atl5p+Feb 23 2007, 01:49 PM)
Yes I have heard of variable pitch props....and you point???

That's a nice plane you have there....have fun. But you seem to think this is a contest between designers, which it isn't....might make a neat thread so why don't you start one and have fun!

My point is YOU bring up limitations with props by asking:

do you know anything about prop diameter, prop pitch, RPM, and STATIC THRUST? Apparently not. As I’ve stated ...blah blah blah

The point is the use of variable pitch props makes your diversion irrelevant as the pitch of the prop can be adjusted to the situation.

It IS a contest between aircraft designers and treadbelt designers.

You claim that the Treadbelt can PREVENT the take off of an aircraft.

You claim to have PROVEN that with your model.

My point is quite simple, given that the type of PLANE is not specified then it can be ANY FRIGGIN PLANE you can design.

On the other hand all the treadbelt designer can do is increase the speed of the treadbelt.

You claim that an aircraft DESIGNER can't design a plane that can take off from a moving runway if that runway can be instantaneously accelerated all the way to the speed of light.

I say you are wrong, because no matter how fast you make the treadbelt go, one can through design still limit how much drag the treadbelt applies (all the way to ZERO) and one can always provide sufficient extra power to make the plane fly.

The aircraft designer will ALWAYS win.

Arthur
Atl5p
QUOTE (adoucette+Feb 23 2007, 02:37 PM)
My point is YOU bring up limitations with props by asking:

do you know anything about prop diameter, prop pitch, RPM, and STATIC THRUST? Apparently not. As I’ve stated ...blah blah blah

The point is the use of variable pitch props makes your diversion irrelevant as the pitch of the prop can be adjusted to the situation.

It IS a contest between aircraft designers and treadbelt designers.

You claim that the Treadbelt can PREVENT the take off of an aircraft.

You claim to have PROVEN that with your model.

My point is quite simple, given that the type of PLANE is not specified then it can be ANY FRIGGIN PLANE you can design.

On the other hand all the treadbelt designer can do is increase the speed of the treadbelt.

You claim that an aircraft DESIGNER can't design a plane that can take off from a moving runway if that runway can be instantaneously accelerated all the way to the speed of light.

I say you are wrong, because no matter how fast you make the treadbelt go, one can through design still limit how much drag the treadbelt applies (all the way to ZERO) and one can always provide sufficient extra power to make the plane fly.

The aircraft designer will ALWAYS win.

Arthur

Yeah, I left that wide open for you on the Var Pitch prop....and you flew through it with flying colors!!! Your variable pitch prop will have NOTHING to do with this situation...the THRUST needed to get moving is in the DIAMETER of the prop....the PITCH can be adjusted for higher TOP END SPEED, that's why they call it 'Pitch speed'.
A variable pitch prop will have nothing to do with the plane's ability to break the deadly grasp of the treadbelt.
Do you not know the difference between thrust and pitch speed?

Or maybe you've discovered a new 'Variable Diameter' prop somewhere that no one knows about? HAHA I am laughing so hard right now, I may choke!

When the plane is at full throttle and 0 IAS on the treadbelt matching plane's speed over the belt, you say you want to change the pitch of the prop? That will do nothing but increase/decrease the load on the engine/motor....it will NOT produce greater/less thrust. Thrust is what you need to get moving....and you're static thrust is already countered by the treadbelt, so increasing the pitch will just bog the engine down...IF that decreases RPM, THEN you will have lower thrust.

It is NOT a contest between designers...it is a riddle that is asking if a treadbelt can prevent a plane from taking off.

If you want to use a VTOL plane, go right ahead....I even encourage you to start a new thread on that very same topic. Good luck to you!! cya later! good by!

A treadbelt CAN prevent my plane from taking off....I don't have a VTOL.

Oh wait....maybe the engineers can design a treadbelt so large that it creates it's own gravity which is so strong that nothing can escape! Wait...that's a statement best saved for your new thread....please start it so we can continue there...just wait for me by the door, I'll be there in a few...I promise!

Chow baby!
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