Pages: 1, 2, 3, 4

Benny

QUOTE
Look, I have just proved that rolling resistance will increase with speed.
Assuming you have done what you claim, you have shown that wheelchair wheels, not necessarily airplane wheels vary with speed. You have not demonstrated a direct connection between the performance of the two and you have not shown that the rolling friction increases until it is equal to the thrust of a plane.

QUOTE (->
 QUOTE Look, I have just proved that rolling resistance will increase with speed.
Assuming you have done what you claim, you have shown that wheelchair wheels, not necessarily airplane wheels vary with speed. You have not demonstrated a direct connection between the performance of the two and you have not shown that the rolling friction increases until it is equal to the thrust of a plane.

It is now YOUR job to prove:
that the rolling friction of airplane wheels DECREASES without bound.
Negative rolling resistance would be a pretty good trick. Actually, negative friction would allow one to build a perpetual motion machine! No, I only need to show that the maximum rolling friction is not sufficient to be of concern, which I have done using the common, accepted formula for friction. That formula for friction is the same one you have been citing for hundreds of pages now as proof that rolling friction can stop the plane!

QUOTE (Atl5p+Dec 6 2006, 01:05 PM)
"For larger velocity, however, it decreases with velocity"?

is not in the Lemaire text at all....sorry Benny....that quote has to do with a rigid cylinder and a sticky surface....not a plane and treadbelt.
I didn't claim it was in the Lemaire text. I don't see a cite from you or NCN, so where did you come up with the idea that it was for a cylinder on a sticky surface?
MikeMonty
QUOTE (Atl5p+Dec 6 2006, 08:31 PM)

Ahh, I see it now:

Nope, don't understand that one bit.

No surprises there then.

Waldorf and Statler must be wetting their pants laughing by now.
Atl5p
QUOTE (Benny+Dec 6 2006, 03:49 PM)

Assuming you have done what you claim, you have shown that wheelchair wheels, not necessarily airplane wheels vary with speed. You have not demonstrated a direct connection between the performance of the two and you have not shown that the rolling friction increases until it is equal to the thrust of a plane.

Negative rolling resistance would be a pretty good trick. Actually, negative friction would allow one to build a perpetual motion machine! No, I only need to show that the maximum rolling friction is not sufficient to be of concern, which I have done using the common, accepted formula for friction. That formula for friction is the same one you have been citing for hundreds of pages now as proof that rolling friction can stop the plane!

I didn't claim it was in the Lemaire text. I don't see a cite from you or NCN, so where did you come up with the idea that it was for a cylinder on a sticky surface?

Gordon is here:
http://www.vard.org/jour/89/26/1/pdf/Gordon.pdf

be ready for Adobe to pop up, if you don't have Adobe you might not get it.

I found the 'Viscous surface' via google....just cut/paste part of the quote, I found the abstract.

Look at Gordon...it is pneumatic tires...that means there's air in them...just like plane tires...look, it's done.

WHEN you use wheelspeed, the plane will never fly! Rolling Resistance increases with speed. There is no difference between Rolling Resistance and Rolling Friction.
AmazedByThis
QUOTE (Atl5p+Dec 6 2006, 07:59 PM)
So, now at least we know that a treadbelt CAN in fact prevent a plane from taking off....if the plane's wheelspeed is matched by the treadbelt....finished, done, where's my cookie?

Uhhh, duh.
That isn't the question!!!! That's like saying "we know X CAN in fact be greater than Y...if X is a larger number." Logically, if the belt matches the "wheelspeed" of the plane (the speed relative to a point on the belt), the plane MUST have no groundspeed or airspeed! The question is, can the treadbelt ever actually MATCH the "wheelspeed" of the plane? That's what we're debating here!
MikeMonty
QUOTE (Atl5p+Dec 6 2006, 08:56 PM)

WHEN you use wheelspeed, the plane will never fly! Rolling Resistance increases with speed. There is no difference between Rolling Resistance and Rolling Friction.

Where in your chosen text does it say rolling resistance increases with speed?
I could be wrong, but I don't see it.

How about giving us the page and line.

I don't need what you infer from the text though, just the facts please.

I think the difference is burnt into the screen of my PC - I've told you often enough!
Atl5p
QUOTE (AmazedByThis+Dec 6 2006, 04:07 PM)
Uhhh, duh.
That isn't the question!!!! That's like saying "we know X CAN in fact be greater than Y...if X is a larger number." Logically, if the belt matches the "wheelspeed" of the plane (the speed relative to a point on the belt), the plane MUST have no groundspeed or airspeed! The question is, can the treadbelt ever actually MATCH the "wheelspeed" of the plane? That's what we're debating here!

Plenty of FlyBoys have stated that when you put my Tonka truck on a treadbelt, attatch a string and a digital scale, check the scale at various speeds, the weight shown on the scale will NEVER change because rolling resistance is not affected by speed.

That was their whole basis for 'It Flies'.

QUOTE
The question is, can the treadbelt ever actually MATCH the "wheelspeed" of the plane?  That's what we're debating here!

This thread, treadbelt matches wheelspeed (or rather, the speed the plane travels over the surface of the moveable treadbelt). I don't know HOW the treadbelt does it, but it DOES.

Nowhere in this question does it ask 'Can the treadbelt KEEP UP with the plane'. Nice try but...well, actually it's not even a very good try.
AmazedByThis
Oh! Good to know! I guess this thread really IS dead because what you're asking in this physics forum isn't even a physics question. It's merely a logic problem. If you're actually saying that "when a treadmill is matching the wheelspeed of the airplane, thus completely canceling its groundspeed, the plane cannot take off, because in the construct of the question I have made it logically impossible to have any groundspeed" then you are absolutely correct! However, that's not what anyone is arguing against. What everyone is (or perhaps should be) saying is, "well that's great, but since it is impossible in the real world with actual laws of physics it's not a very meaningful assertion now, is it?" At least, that's what I'M saying!
Atl5p
QUOTE (MikeMonty+Dec 6 2006, 04:11 PM)
Where in your chosen text does it say rolling resistance increases with speed?
I could be wrong, but I don't see it.

How about giving us the page and line.

I don't need what you infer from the text though, just the facts please.

I think the difference is burnt into the screen of my PC - I've told you often enough!

QUOTE
".... the rolling coefficient of friction is velocity dependent"
page 4 in Adobe, pg 54 on document itself, right column, last paragraph.

QUOTE (->
 QUOTE ".... the rolling coefficient of friction is velocity dependent"
page 4 in Adobe, pg 54 on document itself, right column, last paragraph.

"The solutions of the equations for the wheelchair rolling
resistance involve obtaining the coefficient of rolling friction for the tires, the distance from the rear wheel axle to the patient-wheelchair center of gravity (using the balance platform technique), the weight of the patient-wheelchair, and the wheelbase length. These values are used in Equations 5 and 6 to calculate the rolling friction....."
page 5 adobe, pg 54 on document, left column, last paragraph.

So, when the distance from rear wheel axle to the patient-wheelchair center of gravity, and the weight and the wheelbase remain the same, then any increase in 'rolling coefficient of friction' WILL lead to a direct increase in the rolling friction.

I see your point and it is taken.....increasing beltspeed does not increase rolling friction alone...it increases the coefficient of rolling friction, and when all other factors remain the same, this will ALSO increase the rolling friction.

WHATEVER DUDE! Increase the treadbelt speed, and the opposing FORCE on the plane will increase likewise! It's not exponential, it is linear. This is contrary to what you have been saying all along mah friend....you are incorrect sir!
Bloy
QUOTE (Atl5p+Dec 6 2006, 09:29 PM)
page 4 in Adobe, pg 54 on document itself, right column, last paragraph.

page 5 adobe, pg 54 on document, left column, last paragraph.

So, when the distance from rear wheel axle to the patient-wheelchair center of gravity, and the weight and the wheelbase remain the same, then any increase in 'rolling coefficient of friction' WILL lead to a direct increase in the rolling friction.

I see your point and it is taken.....increasing beltspeed does not increase rolling friction alone...it increases the coefficient of rolling friction, and when all other factors remain the same, this will ALSO increase the rolling friction.

WHATEVER DUDE!  Increase the treadbelt speed, and the opposing FORCE on the plane will increase likewise!  It's not exponential, it is linear.  This is contrary to what you have been saying all along mah friend....you are incorrect sir!

I think (whoever said it), said that it was insignificant.....
insignificant compared to the FORCE? of the bonafide flyable airplane.
Atl5p
QUOTE (AmazedByThis+Dec 6 2006, 04:26 PM)
Oh!  Good to know!  I guess this thread really IS dead because what you're asking in this physics forum isn't even a physics question.  It's merely a logic problem.  If you're actually saying that "when a treadmill is matching the wheelspeed of the airplane, thus completely canceling its groundspeed, the plane cannot take off, because in the construct of the question I have made it logically impossible to have any groundspeed" then you are absolutely correct!  However, that's not what anyone is arguing against.  What everyone is (or perhaps should be) saying is, "well that's great, but since it is impossible in the real world with actual laws of physics it's not a very meaningful assertion now, is it?"  At least, that's what I'M saying!

Re-read the thread...it is what EVERYONE is talking about....they say that the plane will still fly because there is not ENOUGH resistance from the wheels, even when treadbelt matches wheelspeed.

FlyBoy's entire argument has been based on the belief that no matter how fast (infinity) you spin the treadbelt, that ANY plane will ALWAYS fly...even if the belt spins to infinity (which is faster than the fastest speed you can imagine)...even for a model plane that flys at 15mph...the belt could spin to infinity and the plane would still run up and take off.....it is BS, it is now proven wrong.

Everyone say 'Treadbelt CAN and WILL FOREVERMORE hold a plane to 0 IAS, WHEN the treadbelt matches wheelspeed.'

Everyone say that in unison, recant their falshoods, and I it will be settled, I will be vindicated, and I will go away....but everyone must say it in unison.

Of course I realize the rolling resistance is 'small'....but when the belt's speed is increased the rolling resistance get's BIGGER....so that means that there is NO LIMIT how much force can be transfered to the plane via rolling resistance, just keep increasing the treadbelt speed and that force gets bigger all the time....yes even big enough to hold a bonified flyable plane to 0 IAS....and like I have been saying the ENTIRE TIME...that's gotta be one fast spinning treadbelt...but that dam plane aint goin nowhere.
Bloy
QUOTE (Atl5p+Dec 6 2006, 09:44 PM)
Re-read the thread...it is what EVERYONE is talking about....they say that the plane will still fly because there is not ENOUGH resistance from the wheels, even when treadbelt matches wheelspeed.

FlyBoy's entire argument has been based on the belief that no matter how fast (infinity) you spin the treadbelt, that ANY plane will ALWAYS fly...even if the belt spins to infinity (which is faster than the fastest speed you can imagine)...even for a model plane that flys at 15mph...the belt could spin to infinity and the plane would still run up and take off.....it is BS, it is now proven wrong.

Everyone say 'Treadbelt CAN and WILL FOREVERMORE hold a plane to 0 IAS, WHEN the treadbelt matches wheelspeed.'

Everyone say that in unison, recant their falshoods, and I it will be settled, I will be vindicated, and I will go away....but everyone must say it in unison.

Like I said......you are out of the realm of reality.

anything to prove a point, eh atl5p? ....make it unreal for the sake or your argument.

I'm sure if a plane moved to SOME speed that it required for liftoff, say a small plane that lifts off at 75mph, the wheels could be spinning at 150 mph and the belt would be spinning at 150mph oppositely... you DID say the wheelspeed matched the belt speed, didn't you?
In this case THE PLANE FLYS
Atl5p
MikeMonty
QUOTE (Atl5p+Dec 6 2006, 09:29 PM)
page 4 in Adobe, pg 54 on document itself, right column, last paragraph.

page 5 adobe, pg 54 on document, left column, last paragraph.

So, when the distance from rear wheel axle to the patient-wheelchair center of gravity, and the weight and the wheelbase remain the same, then any increase in 'rolling coefficient of friction' WILL lead to a direct increase in the rolling friction.

I see your point and it is taken.....increasing beltspeed does not increase rolling friction alone...it increases the coefficient of rolling friction, and when all other factors remain the same, this will ALSO increase the rolling friction.

WHATEVER DUDE! Increase the treadbelt speed, and the opposing FORCE on the plane will increase likewise! It's not exponential, it is linear. This is contrary to what you have been saying all along mah friend....you are incorrect sir!

Ah yes, thanks for that,
I was looking at the second of your citations there that's the one you linked to.

I had already addressed the first, from which that came, and forgotten about it,
read back if you can be bothered, (I can't be bothered)
You certainly didn't take it in the first time.

Getting bored again, I get bored when the argument has no substance.
"Reductio ad absurdum" is where this is going if its not already there.

Not much point in blowing down your little house of cards because you'll just rebuild it with smaller wobblier cards.

Done the maths on the mat yet? - no don't answer that - I'm actually not interested there either.

Sorry Gonzo, the muppets are getting tiring, be more fun getting fired out of a cannon.
MikeMonty
QUOTE (Atl5p+Dec 6 2006, 10:21 PM)

You get a more powerful belt,
I'll get a more powerful plane,
You get an even more powerful belt,
I'll get an EVEN more powerful plane.
.........

This argument cannot be won on the physics.

But it can be LOST on bad physics Gonzo.

Atl5p
QUOTE (MikeMonty+Dec 6 2006, 05:25 PM)
Ah yes, thanks for that,
I was looking at the second of your citations there that's the one you linked to.

I had already addressed the first, from which that came, and forgotten about it,
read back if you can be bothered, (I can't be bothered)
You certainly didn't take it in the first time.

Getting bored again, I get bored when the argument has no substance.
"Reductio ad absurdum" is where this is going if its not already there.

Not much point in blowing down your little house of cards because you'll just rebuild it with smaller wobblier cards.

Done the maths on the mat yet? - no don't answer that - I'm actually not interested there either.

Sorry Gonzo, the muppets are getting tiring, be more fun getting fired out of a cannon.

You get a more powerful belt,
I'll get a more powerful plane,
You get an even more powerful belt,
I'll get an EVEN more powerful plane.
.........

This argument cannot be won on the physics.

But it can be LOST on bad physics Gonzo.

What is this, some sort of code talk?

Admit it...when we put the plane on the treadbelt, hook a rope to a scale and increase the speed of the belt, the scale's value will increase with each additional constant speed. The treadbelt can spin as fast as it wants, when it matches wheelspeed, this force will equal the 'forward' force of the plane....because the 'backwards' force from the treadbelt will always get bigger with the speed as well.

and about your bigger and badder plane....the OP states that the treadbelt will ALWAYS match the plane's (I say wheelspeed) speed. There IS NO bigger and badder plane than is the treadbelt....the question SAYS the speed is matched.

Dude, just go home to your old 'The question SAYS it moves....speed is determined by IAS' stomping grounds....the plane will always fly over there.

You are sunk, and a bad looser to boot! Imagine that....reduced to 'I'll get a bigger and badder plane' argument....what are you, 6 years old?

rethinker
Seem like the question is simple.
Which has more force? Or are they equal?
The plane going forward or in full thrust, or the belt going backwards.

atl5p says the belt changes speed at the same rate as the plane adds thrust.
This is not enough to stop the plane.
The belt must add many times more force than just the equal of the plane.
To make the plane stay still, enough friction must be created to hold the wheels or lock the bearings.
In just adding equal reverse to the belt, the wheels can spin at this speed without overheating, or beginning to lock.
Show me the money!

Atl5p
QUOTE (rethinker+Dec 6 2006, 05:44 PM)
Seem like the question is simple.
Which has more force? Or are they equal?
The plane going forward or in full thrust, or the belt going backwards.

atl5p says the belt changes speed at the same rate as the plane adds thrust.
This is not enough to stop the plane.
The belt must add many times more force than just the equal of the plane.
To make the plane stay still, enough friction must be created to hold the wheels or lock the bearings.
In just adding equal reverse to the belt, the wheels can spin at this speed without overheating, or beginning to lock.
Show me the money!

beltspeed matches wheelspeed....go read AmazedByThis...he finally has it right...it's just a logic problem.

When IAS is used, plane flies

When wheelspeed is used (speed the plane travels over the surface of the belt - disclaimer), plane cannot fly....simple logic....

FlyBoys have tried to use physics and today they have failed...better start planning your backpeddling/exit strategy fast...before you get caught too deep!
swimmer
QUOTE (Atl5p+Dec 6 2006, 05:09 PM)
Please note, I have cited his source GORDON along with a link.

Velocity of Treadbelt will increase the overall Rolling Resistance....

the overall Rolling Resistance has been found to be velocity dependant,

Also, the "rolling coefficient of friction is velocity dependent,"

as well as the Coefficient of Friction of Tires.

What IS your point?

Have you read Gordon, above?

You are funny ATL5P
(but still a "dumb ***" as you call it)

Months and MONTHS ago (seems like years ago) I asked you numerous times to perform this very experiment with your own treadbelt, your own model plane or skate (anything with wheels) and some weighing scales to one side being pulled on or pushed against. It was to determine if you found any increase or change in the force being applied to your weighing scales by the skate/plane on the treadbelt (a measure of rolling resistance) as you increased the velocity of the treadbelt.

You never did the experiment as far as I could tell.

So I was delighted that you'd found a published paper asking essentially the same question...

...supposedly!

I followed the link, I read the paper, I even scanned the PDF file for the word "velocity" using the search function in Acrobat and I couldn't find it. I tried "speed" and found 6 instances but none associated with rolling resistance. Have you provided the right link? Have you got the right paper?

The data in the paper that most relates to your claims is in figures 5, 6 and 7.
These are graphs of rolling resistance as a function of LOAD, not velocity.

The experiments were carried out at three different velocities 1.5, 2.0 and 3.0mph so using a ruler to read along for any given load you can read off the associated rolling resistance.

I printed the three figures and read across the graphs for the 133lb load on the pneumatic tyres at the three velocities (measured top to bottom of each data point) :

1.5mph : 1.25-1.3lb
2.0mph : 1.26-1.32lb
3.0mph : 1.32-1.38lb

It's a very narrow range of velocities to draw any conclusions and we certainly can't extrapolate to the plane's take off speed. And frankly I can't be arsed to read off any more...
...so very tentatively - for what it's worth, a doubling (or 100% increase) of treadmill speed gives a 1.06 fold (or 6%) increase in rolling resistance.

Is this what you are talking about ATL5P? Or are you too much of a "dumb ***" to read anything properly?

Actual Pilot
QUOTE (Atl5p+Nov 22 2006, 07:23 PM)
A plane is sitting on a moveable runway, like a treadbelt. The plane tries to take off in one direction, while the treadbelt moves in the opposite direction. The treadbelt has a control system to measure the plane's grounspeed over the runway, and the treadbelt matches this speed exactly.

Is the plane able to fly? Does it run up and fly?

I say "NO". What do you say, and why?

This question is meaningless. If the plane moves ANY distance over the belt, the belt will move opposite the aircraft. This will INCREASE the aircraft's speed over the belt due to the motion of the belt itself! Then the belt must speed up to try match the ever-increasing speed. The airplane will have moved a millimeter and the belt will spin up to infinite velocity even if the engine is shut down.

So if you are asking about a belt that accelerates to infinite velocity the instant the aircraft begins to roll, you might as well ask: "Daddy, if an airplane tried to take off and a giant boot came from the sky and stomped on it, could it take off? Could it? Could it?"

It's an asinine hypothetical.

What if what the question really meant was: "belt turns to match the aircraft's speed over the ground?"

The wheels don't propel the aircraft, the thrust does. The aircraft will accelerate, the belt will move in an opposite direction up to double the liftoff speed at which point the aircraft will lift off with the wheels spinning at twice the normal liftoff speed, no problem. The wheel bearings won't be as happy as they could be, but the friction won't stop the plane. Especially since, as the plane gains airspeed, the wheels carry less weight as the wings transition to supporting the weight of aircraft.
swimmer
QUOTE (Actual Pilot+Dec 6 2006, 11:07 PM)
This question is meaningless.  If the plane moves ANY distance over the belt, the belt will move opposite the aircraft. This will INCREASE the aircraft's speed over the belt due to the motion of the belt itself!  Then the belt must speed up to try match the ever-increasing speed. The airplane will have moved a millimeter and the belt will spin up to infinite velocity even if the engine is shut down.

So if you are asking about a belt that accelerates to infinite velocity the instant the aircraft begins to roll, you might as well ask: "Daddy, if an airplane tried to take off and a giant boot came from the sky and stomped on it, could it take off?  Could it? Could it?"

It's an asinine hypothetical.

What if what the question really meant was: "belt turns to match the aircraft's speed over the ground?"

The wheels don't propel the aircraft, the thrust does.  The aircraft will accelerate, the belt will move in an opposite direction up to double the liftoff speed at which point the aircraft will lift off with the wheels spinning at twice the normal liftoff speed, no problem.  The wheel bearings won't be as happy as they could be, but the friction won't stop the plane.  Especially since, as the plane gains airspeed, the wheels carry less weight as the wings transition to supporting the weight of aircraft.

Yes but that ATL5P's speciality.

Surely you can't deny him his daily dose of asininity !

Hmm... that's almost an anagram of something? What can it be...

MikeMonty
QUOTE (Atl5p+Dec 6 2006, 10:43 PM)
What is this, some sort of code talk?

Admit it...when we put the plane on the treadbelt, hook a rope to a scale and increase the speed of the belt, the scale's value will increase with each additional constant speed.  The treadbelt can spin as fast as it wants, when it matches wheelspeed, this force will equal the 'forward' force of the plane....because the 'backwards' force from the treadbelt will always get bigger with the speed as well.

and about your bigger and badder plane....the OP states that the treadbelt will ALWAYS match the plane's (I say wheelspeed) speed.  There IS NO bigger and badder plane than is the treadbelt....the question SAYS the speed is matched.

Dude, just go home to your old 'The question  SAYS it moves....speed is determined by IAS' stomping grounds....the plane will always fly over there.

You are sunk, and a bad looser to boot!  Imagine that....reduced to 'I'll get a bigger and badder plane' argument....what are you, 6 years old?

"Admit it...when we put the plane on the treadbelt, hook a rope to a scale and increase the speed of the belt, the scale's value will increase with each additional constant speed. "
Nope - I can say from personal experience that friction rolling or otherwise is independent of speed for all practical purposes,
I can use the example of mechanical shaft seals in compressors for which I do not have to make any extra allowance on the power of the motor to make go faster.

"and about your bigger and badder plane....the OP states that the treadbelt will ALWAYS match the plane's (I say wheelspeed) speed."

And I say it makes no difference, and you don't accept that - so where does that leave us?

"Imagine that....reduced to 'I'll get a bigger and badder plane' argument...."

It's a valid argument that the whole thing cannot be won on the quantitative level.
There's no difference in the principles here or in the other thread, you are flying in both.
MikeMonty
QUOTE (Actual Pilot+Dec 6 2006, 11:07 PM)
This question is meaningless. If the plane moves ANY distance over the belt, the belt will.....

There are guys walking around with t-shirts with what you just wrote printed on them!
Where can I get one?

Take my advice, don't get sucked into it - down this road, or conveyor, lies madness!

And most of it belongs to one guy.

gmilam
QUOTE (Actual Pilot+Dec 6 2006, 05:07 PM)
This question is meaningless. If the plane moves ANY distance over the belt, the belt will move opposite the aircraft. This will INCREASE the aircraft's speed over the belt due to the motion of the belt itself! Then the belt must speed up to try match the ever-increasing speed. The airplane will have moved a millimeter and the belt will spin up to infinite velocity even if the engine is shut down.

So if you are asking about a belt that accelerates to infinite velocity the instant the aircraft begins to roll, you might as well ask: "Daddy, if an airplane tried to take off and a giant boot came from the sky and stomped on it, could it take off? Could it? Could it?"

It's an asinine hypothetical.

What if what the question really meant was: "belt turns to match the aircraft's speed over the ground?"

The wheels don't propel the aircraft, the thrust does. The aircraft will accelerate, the belt will move in an opposite direction up to double the liftoff speed at which point the aircraft will lift off with the wheels spinning at twice the normal liftoff speed, no problem. The wheel bearings won't be as happy as they could be, but the friction won't stop the plane. Especially since, as the plane gains airspeed, the wheels carry less weight as the wings transition to supporting the weight of aircraft.

Yeah, we know. We've explained it to him hundreds of times in hundreds of different ways.

But feel free to bang your head against the wall for a while if you really want to.
Bloy
That's what I meant when I said ATL5p is out of the realm of reality....
See ALL of the above posts by atl5p

Insanity....definition
....Persistent mental disorder or derangement. No longer in scientific use.

therefore, insanity = Atl5p
AmazedByThis
QUOTE (Atl5p+Dec 6 2006, 10:47 PM)
beltspeed matches wheelspeed....go read AmazedByThis...he finally has it right...it's just a logic problem.

Please note everyone, this is what atl5p says is the correct way to view this problem.
QUOTE
what you're asking in this physics forum isn't even a physics question. It's merely a logic problem. If you're actually saying that "when a treadmill is matching the wheelspeed of the airplane, thus completely canceling its groundspeed, the plane cannot take off, because in the construct of the question I have made it logically impossible to have any groundspeed" then you are absolutely correct!

To repeat with emphasis, atl5p is telling everyone that this question she posed has nothing to do with physics, or for that matter, reality. If you look at from a purely logical (as in if a, b... if b, c... therefore if a...c kinda logic NOT "seems logical to me" kinda logic) standpoint, if the wheelspeed of the plane on the belt is equal and opposite to the speed of the belt over the ground, the plane does not by definition have any groundspeed. Nothing at all to do with a real airplane, a real treadmill, or a real newtonian universe. It's a brain teaser! Now ask yourself this...
If Atl5p from the getgo meant this as a logic problem, why has she been arguing on and on about friction, rolling resistance, etc.?

a: just to be creepy and confuse distract people even further from the logical answer
or
b: that isn't really the way this question started out
which one is your money on?

hint:
Atl5p
Another great article on Rolling Resistance...this time it's a car instead of a wheechair..
http://www.tirerack.com/tires/tiretech/tec...e.jsp?techid=29

QUOTE
During stop-and-go city driving, it's estimated that overcoming inertia is responsible for about 35% of the vehicle's resistance. Driveline friction is about 45%; air drag is about 5% and tire rolling resistance is about 15%.

Overcoming inertia no longer plays an appreciable role in the vehicle's resistance during steady speed highway driving. For those conditions it is estimated that driveline friction is about 15%; air drag is about 60% and tire rolling resistance represent about 25%.

Keep in mind, these are % of the whole...rolling resistance is a significant force to overcome....

Again, if the belt had to spin up to infinity and beyond, then how could my tonka/ace be held to 0 IAS? No my comrades..there IS a speed that will work in ANY situation...and it is no where near infinity. Seriously..anyone who uses that term to describe this situation, how could they possibly have credibility?
Atl5p
Holy Crap....Seriously, you guys....HEY!!!!

Check THIS out!
http://www.vejdirektoratet.dk/publikatione...l/chapter05.htm

I don't know where it is from, but it sure sounds good to me!

QUOTE
The rolling resistance force is increased as the speed increases [17]. The following is a simplified equation for this:

Rolling resistance force = constant1 + constant2 * velocity      (1)

The coefficient of rolling resistance is nearly constant over the practical range of loads, meaning that the rolling resistance force is proportional to the load applied to the tyre [17]. The rolling resistance force decreases when the inflation pressure is raised [17].

The rolling resistance is the force required to push a vehicle over the surface it is rolling over. The rolling resistance force might be expressed in different ways.

1. Rolling resistance in Newton per hundred kilograms (RR). This is the total weight in kg of the vehicle (W), times the rolling resistance of the road surface ® divided by 100. R is the rolling resistance in Newton per hundred kilograms of vehicle weight. The result comes in Newton (N):

RR=W*R/100      (2)

2. Rolling resistance factor per kilogram of total vehicle weight (Q):

Q=R/100      (3)

3. A third method of expressing road rolling resistance is percent of grade (RR%). To do so, the rolling resistance pr hundred kilograms of vehicle ® is multiplied by 100 and divided by 1000. The result comes in percent (%):

RR%=R*100/1000      (4)

Also:
QUOTE (->
 QUOTE The rolling resistance force is increased as the speed increases [17]. The following is a simplified equation for this: Rolling resistance force = constant1 + constant2 * velocity      (1) The coefficient of rolling resistance is nearly constant over the practical range of loads, meaning that the rolling resistance force is proportional to the load applied to the tyre [17]. The rolling resistance force decreases when the inflation pressure is raised [17]. The rolling resistance is the force required to push a vehicle over the surface it is rolling over. The rolling resistance force might be expressed in different ways. 1. Rolling resistance in Newton per hundred kilograms (RR). This is the total weight in kg of the vehicle (W), times the rolling resistance of the road surface ® divided by 100. R is the rolling resistance in Newton per hundred kilograms of vehicle weight. The result comes in Newton (N): RR=W*R/100      (2) 2. Rolling resistance factor per kilogram of total vehicle weight (Q):Q=R/100      (3) 3. A third method of expressing road rolling resistance is percent of grade (RR%). To do so, the rolling resistance pr hundred kilograms of vehicle ® is multiplied by 100 and divided by 1000. The result comes in percent (%): RR%=R*100/1000      (4)

Also:
Standard test method
ISO have published a standard for measuring of the rolling resistance of tyres for passenger cars [11]. It is a laboratory method where the rolling resistance is measured under controlled conditions. The method does not include a relation between the measured rolling resistance end the fuel consumption of a given vehicle. The rolling resistance is defined as the loss of energy per unit of distance. And the rolling resistance coefficient is defined as the rolling resistance divided by the load of the tyre (in Newton). The testing is carried out when the tyre is rolling on a drum with a smooth surface.

So, when I ask the following question:

"My tonka/aero-ace would be held steady 0 IAS at a certian belt speed, but then when I increased the beltspeed the plane then had 0 IAS"

"Why, that was a clear demonstration of Increased Rolling Resistance Force, Mr Atl5p SIR!".
egnorant
QUOTE (Atl5p+Dec 6 2006, 10:47 PM)
beltspeed matches wheelspeed....go read AmazedByThis...he finally has it right...it's just a logic problem.

When IAS is used, plane flies

When wheelspeed is used (speed the plane travels over the surface of the belt - disclaimer), plane cannot fly....simple logic....

FlyBoys have tried to use physics and today they have failed...better start planning your backpeddling/exit strategy fast...before you get caught too deep!

Yes, if we used wheelspeed it would not fly!
If we used wheelspeed the plane is trapped solidly to whatever you measure the belt against (ground).
Forces are only what is needed to produce the described result..
Nothing more, nothing less!
Even if the forces needed are ridiculous...it doesn't matter.
Its a simple word problem.
Just read the words and use them to get the correct answer.
If you had left out a few letters I would have been on board with ya on this question.
Those letters are g,r,o,u and n.
I really took this to mean ground rather than groun.
Groun is a common spelling of a slang or rural pronunciation of ground.

You then explained that "planes groun(d)speed over the belt WAS wheelspeed.
Not that you are changing what you wrote...you claimed we misunderstood what you wrote!
Had you said "planes speed over the belt"...O.K.
Had you said "planes wheelspeed over the belt"...still O.K.
But you used planes groundspeed over the belt.
This has the planes speed relative to the ground....
Suppose you had said "planes AIRspeed over the belt", would you have doubted that the plane is moving relative to the air?

It is a word problem!
And as it is written....The plane flies!

Bruce
"Honest Judge he slammed his head against my baseball bat several times.....if you look at it like this.."

Atl5p
I learned a new word today. It is 'Rolling Resistance Force'. It is good. New words are good.

http://www.tut.fi/plastics/tyreschool/modu...xt_1/3/3_3.html

and methods and equipment section...not to be missed...
http://www.tut.fi/plastics/tyreschool/modu...xt_2/2/2_2.html

Maybe the 'Roll Down Test' is sort of like the 'Greased Mat Test'...I wonder if it slows down at a more rapid rate at higher speeds....I'll bet i'll bet...

crazy charts and graphs....matches plane's groundspeed over the runway....yeah, it meant wheelspeed. Buy you are the one Bruce who always ridiculed my use of wheelspeed.

sorry boy....all your lines are still out there...I'll go get'em one day and feed 'em to ya...

Treadbelt can prevent a plane from flying....see ya on the 'Trick Question' forum some time!!

QUOTE

Rolling resistance force

--------------------------------------------------------------------------------

The most usual way to represent the tyre energetic losses is rolling resistance force that acts in the wheel axis. Its value multiplied by the distance covered by the tyre yields the work value consumed for the displacement and hence the total energy lost in the rolling process.
Rolling speed - In the case of measurements carried out at an equilibrium temperature on a capped tyre, a certain reduction in the rolling resistance is noticed with slower running speeds. The explanation lies in the stronger influence of thermal factors, which diminish hysteresis losses and increase tyre pressure rather than the dynamic factors, which cause its increase. In the range of moderate speeds (40 to 80 km/h) the rolling resistance is kept approximately constant or increases slightly in a linear manner (figure 4), while in the range of high speeds they start to increase rapidly. This is accounted for by the very high (developing) inertia forces. These inertia forces cause the restitution of an ever-smaller amount from the elastic deformation energy, inducing also the vibration of the tyre tread (stationary waves). The energy of the vibration is then consumed via the hysteresis of the material. This trend is more evident on passenger car tyres than on larger truck tyres. The explication consists in the much higher stiffness of truck tyres construction and inflation pressure.

In the case of measurements done at equilibrium temperature with inflation pressure kept constant, it could be observed higher speed dependence, the rolling resistance increasing all the time.

In the third case, at constant temperature when data are taken immediately after change, appears the most pronounced increasing with speed (figure 5).

And then little graphs with lines pointed upwards left to right...as speed increases so does the rolling resistance...oh yeah, 'force'...rolling resistance force.
egnorant
QUOTE (Atl5p+Dec 7 2006, 05:09 AM)
....matches plane's groundspeed over the runway....yeah, it meant wheelspeed. Buy you are the one Bruce who always ridiculed my use of wheelspeed.

So are you saying you wrote the question wrong or are you wanting us to understand that "planes groundspeed over the belt" is the correct way to state wheelspeed?

Bruce
Benny
Your arrogance is just amazing, considering that three weeks ago I explicitly told you that you had to contradict your previous citation explaining rolling friction. You should have figured it out months and months before I posted. What took you so long?
QUOTE (Benny+)
Atl, you can hamper my arguments by stating that you no longer believe that http://auto.howstuffworks.com/tire4.htm contains the correct formulas to use in solving the problem. The formulas and analysis I am using are supported by that article. Until and unless you state that either the article is incorrect or admit that your experiment is inappropriate and inapplicable your arguments are self-contradictory. So long as your arguments are self-contradictory you can never be correct and can never win.

QUOTE (AmazedByThis+)
Oh! Good to know! I guess this thread really IS dead because what you're asking in this physics forum isn't even a physics question. It's merely a logic problem....
So this should be in the Trick Question Forum and not a Physics Forum? Wow, I bet Atl5p will go ballistic when he finds that someone posted a trick question in the physics forum! Arrogant and Hypocritical and Slow! What a combination!

F=uN is the correct method for calculating the rolling friction of imaginary wheels. Nothing that you post will ever change that.

In the end it doesn't matter if a conveyor can hold back a plane. Both the original question and your question have the conveyor matching the groundspeed of the plane and it will take off and fly.

PS: How does the increasing rolling friction stop the plane? Does it match the power or work or what?
Atl5p
QUOTE (egnorant+Dec 7 2006, 12:39 AM)
So are you saying you wrote the question wrong or are you wanting us to understand that "planes groundspeed over the belt" is the correct way to state wheelspeed?

Bruce

I didn't say 'EarthSpeed' did I....I said 'Groundspeed over the moving runway.' See, the treadbelt is supposed to be some sort of moving runway, one that the plane rolls on..it is the plane's 'ground' so to speak. Whatever the terminology.

Look Bruce, it's OK...you were NOT inclined to agree, you were too busy splitting hairs over the way the question was worded...if you really wanted to say that wheelspeed = no fly then I believe you would have....I understand this is your way of backpeddling...it's OK...don't worry..when I get the time I will find your posts.
egnorant
QUOTE (Atl5p+Dec 7 2006, 03:00 PM)
I didn't say 'EarthSpeed' did I....I said 'Groundspeed over the moving runway.' See, the treadbelt is supposed to be some sort of moving runway, one that the plane rolls on..it is the plane's 'ground' so to speak. Whatever the terminology.

Look Bruce, it's OK...you were NOT inclined to agree, you were too busy splitting hairs over the way the question was worded...if you really wanted to say that wheelspeed = no fly then I believe you would have....I understand this is your way of backpeddling...it's OK...don't worry..when I get the time I will find your posts.

If you wish to find where I said wheelspeed = no fly, just look about 3 posts ago.
Face it, you screwed up the wording of the question and won't admit it.
I have always maintained that wheelspeed version = no fly.
I still have doubts that anything will ever move using wheelspeed theory.
Only 4 elements here...ground, belt, plane and air.
I know part of the fun is clever wording and misdirection to trap folks into incorrect viewpoints, but you just botched this one.

Earthspeed...now thats funny!

Bruce
Atl5p
QUOTE (egnorant+Dec 7 2006, 10:29 AM)
If you wish to find where I said wheelspeed = no fly, just look about 3 posts ago.
Face it, you screwed up the wording of the question and won't admit it.
I have always maintained that wheelspeed version = no fly.
I still have doubts that anything will ever move using wheelspeed theory.
Only 4 elements here...ground, belt, plane and air.
I know part of the fun is clever wording and misdirection to trap folks into incorrect viewpoints, but you just botched this one.

Earthspeed...now thats funny!

Bruce

Then I suppose I don't understand your post below:
QUOTE
Yes, if we used wheelspeed it would not fly!
If we used wheelspeed the plane is trapped solidly to whatever you measure the belt against (ground).
Forces are only what is needed to produce the described result..
Nothing more, nothing less!
egnorant
QUOTE (Atl5p+Dec 7 2006, 03:39 PM)
Then I suppose I don't understand your post below:

QUOTE
Yes, if we used wheelspeed it would not fly!
If we used wheelspeed the plane is trapped solidly to whatever you measure the belt against (ground).
Forces are only what is needed to produce the described result..
Nothing more, nothing less

As written, the question does not use wheelspeed!
As written the plane has speed relative to the ground.
Forces are only what is needed to produce the described result..
Nothing more, nothing less

What part do you not understand?

Bruce
Actual Pilot
QUOTE (Atl5p+Dec 7 2006, 03:38 AM)
...if the belt had to spin up to infinity and beyond, then how could my tonka/ace be held to 0 IAS?  No my comrades..there IS a speed that will work in ANY situation...and it is no where near infinity.  Seriously..anyone who uses that term to describe this situation, how could they possibly have credibility?

Yup, I used the term. Does questioning my credibility in some snide way that you find amusing, increase your credibility? In your mind I'm sure it does.

Now, without the lame, troll tactics of: "completely avoiding the question and changing the subject" or "resorting to cutesy insults", I want you to answer this question, right here, in front of everyone:

Since rolling friction is independent of velocity, what belt velocity will it take to counteract the thrust of the aircraft?

It makes no difference that some googled tire site says rolling resistance is 25%, IT DOESN'T INCREASE WITH VELOCITY!

I know you won't address this directly; you'll make fun of me in a way that will give you some entertainment value, while completely ignoring what I just said. Watch closely everyone, at the totally predictable troll behavior.
Atl5p
QUOTE (Actual Pilot+Dec 7 2006, 12:42 PM)
Yup, I used the term. Does questioning my credibility in some snide way that you find amusing, increase your credibility? In your mind I'm sure it does.

Now, without the lame, troll tactics of: "completely avoiding the question and changing the subject" or "resorting to cutesy insults", I want you to answer this question, right here, in front of everyone:

Since rolling friction is independent of velocity, what belt velocity will it take to counteract the thrust of the aircraft?

It makes no difference that some googled tire site says rolling resistance is 25%, IT DOESN'T INCREASE WITH VELOCITY!

I know you won't address this directly; you'll make fun of me in a way that will give you some entertainment value, while completely ignoring what I just said. Watch closely everyone, at the totally predictable troll behavior.

That's funny...someone who is unregistered, and just showed up, is calling folks 'Trolls'....HAHAHA! YOU made the funny, not me!

I've posted several articles that show how Rolling Resistance Force will increase with velocity. I'm not a physisiststs....so maybe you could help explain Rolling Resistance Force and it's relationship with velocity to me!
laughing my azz off
QUOTE (Atl5p+Dec 7 2006, 05:59 PM)
I'm not a physisiststs....so maybe you could help explain Rolling Resistance Force and it's relationship with velocity to me!

In addition to your crazy misspelling in this quote, I find it absolutely hilarious that you're asking for help understanding the relationship of the force of rolling resistance and velocity. You need help with that and you're willing to argue, attempt to belittle people with intelligence, and otherwise act a fool while trying to prove an impossible outcome of the problem at hand? Funny stuff!
MikeMonty
Oh look AT...thingy
I can do this too!
I googled "velocity" "friction" and "independence" and heres the first authoritative source that came up - on the first page of hits - a University site.

They say
"1. The frictional force is independent of area of contact [with] Exceptions
2. The frictional force is independent of the velocity of motion [with] Exceptions
3. The frictional force is proportional to the normal force. [with] Exceptions

One can readily find circumstances where any or all of these assumptions are invalid, but they provide a straightforward framework for a beginning treatment of friction that satisfactorily describes many phenomena. "

Now I'm sure you disagree, which is why I've prepared a little response on your behalf that you can send to them:

Dear Georgia State University,
My name is Gonzo, you may remember me from such films as "Muppets in Space".

I have absolutely no training in Applied Mechanics and haven't a clue what I'm talking about, but this shouldn't mean that I can't be right if I talk loud and long enough.

I have to take issue with you on your article on friction. I feel that you have placed far too much emphasis on the "independence" thingy to the detriment of the exceptions.
Please ensure that this is rectified - I wish to see the exceptions first and foremost.
If you MUST mention the GENERAL rule, I insist that you have it in very small print in an envelope in your basement.

Gonzo
Guest
QUOTE (Atl5p+Dec 7 2006, 05:59 PM)
That's funny...someone who is unregistered, and just showed up, is calling folks 'Trolls'....HAHAHA! YOU made the funny, not me!

Responded exactly as predicted.

Case closed.

As is the case for rolling friction.
MikeMonty
QUOTE (Actual Pilot+Dec 7 2006, 05:42 PM)
Yup, I used the term. Does questioning my credibility in some snide way that you find amusing, increase your credibility? In your mind I'm sure it does.

Now, without the lame, troll tactics of: "completely avoiding the question and changing the subject" or "resorting to cutesy insults", I want you to answer this question, right here, in front of everyone:

Since rolling friction is independent of velocity, what belt velocity will it take to counteract the thrust of the aircraft?

It makes no difference that some googled tire site says rolling resistance is 25%, IT DOESN'T INCREASE WITH VELOCITY!

I know you won't address this directly; you'll make fun of me in a way that will give you some entertainment value, while completely ignoring what I just said. Watch closely everyone, at the totally predictable troll behavior.

I warned you!
And now that he's challenged you, you may feel that you have to respond, not because he's in any way countered your argument, but because you wouldn't want anyone ELSE think that you are backing down.

Ask him to explain his assertions - good for a laugh - his choices are:
1. Ignore
2. Feign misunderstanding
3. Abuse
4. Admit ignorance and ask you to explain to him whereupon he will do one of the above again.

Vicious circle!
Atl5p
QUOTE (MikeMonty+Dec 7 2006, 01:30 PM)
Oh look AT...thingy
I can do this too!
I googled "velocity" "friction" and "independence" and heres the first authoritative source that came up - on the first page of hits - a University site.

They say
"1. The frictional force is independent of area of contact [with] Exceptions
2. The frictional force is independent of the velocity of motion [with] Exceptions
3. The frictional force is proportional to the normal force. [with] Exceptions

One can readily find circumstances where any or all of these assumptions are invalid, but they provide a straightforward framework for a beginning treatment of friction that satisfactorily describes many phenomena. "

Now I'm sure you disagree, which is why I've prepared a little response on your behalf that you can send to them:

Dear Georgia State University,
My name is Gonzo, you may remember me from such films as "Muppets in Space".

I have absolutely no training in Applied Mechanics and haven't a clue what I'm talking about, but this shouldn't mean that I can't be right if I talk loud and long enough.

I have to take issue with you on your article on friction. I feel that you have placed far too much emphasis on the "independence" thingy to the detriment of the exceptions.
Please ensure that this is rectified - I wish to see the exceptions first and foremost.
If you MUST mention the GENERAL rule, I insist that you have it in very small print in an envelope in your basement.

Gonzo

Sorry, I can't find the term 'Rolling Resistance Force', and I also fail to see where they hooked up a wheeled vehicle to a scale and put it on a treadbelt...

MikeMonty
QUOTE (Atl5p+Dec 7 2006, 07:07 PM)
Sorry, I can't find the term 'Rolling Resistance Force', and I also fail to see where they hooked up a wheeled vehicle to a scale and put it on a treadbelt...

his choices are:
1. Ignore
2. Feign misunderstanding
3. Abuse
4. Admit ignorance and ask you to explain to him whereupon he will do one of the above again.

And this time we picked.... Number two!
Atl5p
QUOTE (MikeMonty+Dec 7 2006, 02:11 PM)
his choices are:
1. Ignore
2. Feign misunderstanding
3. Abuse
4. Admit ignorance and ask you to explain to him whereupon he will do one of the above again.

And this time we picked.... Number two!

Your article had absolutly nothing to do with Rolling Resistance Force...I was trying to be nice about it...but you won't let me...it had nothing to do with whether or not a treadbelt could hold a plane to 0 IAS.

Try this one on for size:
http://www.tut.fi/plastics/tyreschool/modu...xt_1/3/3_3.html
QUOTE
In the case of measurements carried out at an equilibrium temperature on a capped tyre, a certain reduction in the rolling resistance is noticed with slower running speeds. The explanation lies in the stronger influence of thermal factors, which diminish hysteresis losses and increase tyre pressure rather than the dynamic factors, which cause its increase. In the range of moderate speeds (40 to 80 km/h) the rolling resistance is kept approximately constant or increases slightly in a linear manner (figure 4), while in the range of high speeds they start to increase rapidly. This is accounted for by the very high (developing) inertia forces. These inertia forces cause the restitution of an ever-smaller amount from the elastic deformation energy, inducing also the vibration of the tyre tread (stationary waves). The energy of the vibration is then consumed via the hysteresis of the material. This trend is more evident on passenger car tyres than on larger truck tyres. The explication consists in the much higher stiffness of truck tyres construction and inflation pressure.

In the case of measurements done at equilibrium temperature with inflation pressure kept constant, it could be observed higher speed dependence, the rolling resistance increasing all the time.

In the third case, at constant temperature when data are taken immediately after change, appears the most pronounced increasing with speed (figure 5).
MikeMonty
QUOTE (Atl5p+Dec 7 2006, 07:36 PM)
Your article had absolutly nothing to do with Rolling Resistance Force...I was trying to be nice about it...but you won't let me...it had nothing to do with whether or not a treadbelt could hold a plane to 0 IAS.

Try this one on for size:
http://www.tut.fi/plastics/tyreschool/modu...xt_1/3/3_3.html

You seem to switch between friction and resistance at will.

Let's examine the text at hand:
In the case of measurements carried out at an equilibrium temperature on a capped tyre, a certain reduction in the rolling resistance is noticed with slower running speeds.
Less than 40 KPH
The explanation lies in the stronger influence of thermal factors, which diminish hysteresis losses and increase tyre pressure rather than the dynamic factors, which cause its increase.
Rolling resistance is lower - ok.....
In the range of moderate speeds (40 to 80 km/h) the rolling resistance is kept approximately constant or increases slightly in a linear manner (figure 4),
40 to 80 - constant but unspecified and unspecifiable
while in the range of high speeds they start to increase rapidly.
Looks like you might have something here!
This is accounted for by the very high (developing) inertia forces. These inertia forces cause the restitution of an ever-smaller amount from the elastic deformation energy,
The tyre is "spun out" by centrifugal force and you don't get back what you put in
inducing also the vibration of the tyre tread (stationary waves). The energy of the vibration is then consumed via the hysteresis of the material. This trend is more evident on passenger car tyres than on larger truck tyres.
The tyre "hums/vibrates" and this wastes energy
The explication consists in the much higher stiffness of truck tyres construction and inflation pressure.

In the case of measurements done at equilibrium temperature with inflation pressure kept constant, it could be observed higher speed dependence, the rolling resistance increasing all the time.
OH OH! - they adjusted the pressure to keep it as soft as it was at the start!
In the third case, at constant temperature when data are taken immediately after change, appears the most pronounced increasing with speed (figure 5).

Very good ATL5P that's the first time I've seen you find something that could be used in your favour.

I'll accept your source grudgingly because I can't argue.

Still doesn't help much though, all it means is that the plane has to take off before this unspecified increasing force gets too big.

And if you want to ignore the physics of a massive conveyor we're back to "I'll make my plane more powerful than your conveyor"
Fynlcut
QUOTE
Because the heat transfer to the environment increases slower than heat generation, a gradual increase of tyre temperature appears. Higher temperature will reduce the hysteresis losses and increase the inflation pressure. Due to these effects the rolling resistance decrease (i.e. for a 385/65 R 22.5 tyre with 25 kN load and a final speed of 60 km/h, the inflation pressure increases from 600 to 678 kPa and the rolling resistance force decreases from 172 to 127 N [6]).

Wait, what is it, it increases, or decreases?
Atl5p
If the plane has any IAS, then that means the wheelspeed is greater than treadbelt speed....that will not happen when treadbelt matches wheelspeed Exactly...but we'll play devil's advocate, so in a split second let's say there is a sliver of airspeed, and the wheelspeed/treadbelt speed is in this 'wishywashy'range of what you seem to call questionable rolling resistance force , thus the sliver of IAS (with me so far?), .... for example, maybe there is a drop in Rolling Resistance Force right around 20kph, and the wheels go faster than treadbelt speed thus sliver of IAS....you are forgetting one thing, the treadbelt quickly 'matches' this speed, matches again, matches again, until the treadbelt and wheels are spinning above 100kph and the Rolling Resistance Force is now increasing all the time.

So, please tell me exactly what wheelspeed/treadbeltspeed/IAS in this example the plane will be able to generate enough IAS for takeoff before the treadbelt catches up and continues to match wheelspeed 'Exactly'?

It seems as if you are saying the plane needs to take off at a wheelspeed below 40kph....for example wheelspeed = 25kph and beltspeed = 20kph, thus IAS = 5kph? That's the best I can do...what would you say? What 747 jumbo jet can take off at 5kph? (do you like it when I use 747's now?)
MikeMonty
QUOTE (Fynlcut+Dec 7 2006, 08:32 PM)

Wait, what is it, it increases, or decreases?

I was throwing him a bone dammit!
MikeMonty
QUOTE (Atl5p+Dec 7 2006, 08:39 PM)
So, please tell me exactly what wheelspeed/treadbeltspeed/IAS in this example the plane will be able to generate enough IAS for takeoff before the treadbelt catches up and continues to match wheelspeed 'Exactly'?

It seems as if you are saying the plane needs to take off at a wheelspeed below 40kph....for example wheelspeed = 25kph and beltspeed = 20kph, thus IAS = 5kph? That's the best I can do...what would you say? What 747 jumbo jet can take off at 5kph? (do you like it when I use 747's now?)

Ah now THATS a combination of numbers two and four!
Bloy
Just to interject here....
My interpretation of Atl5p's OP here is that the runway is "movable"(on wheels or something). So the runway is moved along with the plane as the belt matches the belts speed to the plane's speed.
As the plane accelerates, the movable runway(belt and all) follows along until the plane takes off.

One could have a conceivably short runway as long as it fit under the plane....like a treadmill.
Granted though, the "ground" would have to be of some considerable length.

Regardless of the belt or wheelspeed, the plane takes off while the belt speed is still matching the plane speed.

It's all in interpretation...
MikeMonty
QUOTE (Bloy+Dec 7 2006, 08:57 PM)
Just to interject here....
My interpretation of Atl5p's OP here is that the runway is "movable"(on wheels or something).  So  the runway is moved along with the plane as the belt matches the belts speed to the plane's speed.
As the plane accelerates, the movable runway(belt and all) follows along until the plane takes off.

One could have a conceivably short runway as long as it fit under the plane....like a treadmill.
Granted though, the "ground" would have to be of some considerable length.

Regardless of the belt or wheelspeed, the plane takes off while the belt speed is still matching the plane speed.

It's all in interpretation...

Interesting!
I hadn't considered that arrangement.
Certainly reduce the required power.
Still moot though,
The whole thing is still unanswerable until someone states "this is real-world" or "this is entirely hypothetical".

Found myself working out masses and inertias of a belt on excel the other day - until I realised WHAT I was doing!
AmazedByThis
QUOTE (MikeMonty+Dec 7 2006, 09:21 PM)
Still moot though,
The whole thing is still unanswerable until someone states "this is real-world" or "this is entirely hypothetical".

Found myself working out masses and inertias of a belt on excel the other day - until I realised WHAT I was doing!

That's funny... I was spending a bunch of time trying to figure out what belt speed would be required to hold back a Cessna 150, when I realized the same thing. I still maintain that there are only a few possible outcomes to this problem, based on how far you want to stretch reality.

*** Attention Atl5p ***
I get the feeling you tend to sort of not really read long posts very well/much/often, so I'm letting you know that I'm calling you out here.

The Four Possible Ways To Look At This Problem... I think

1) Complete fantasy (well, almost!) -
If you choose to endow your plane with magic immortal landing gear BUT curiously enough, even though it's magic, it still has rolling resistance that increases with the speed of the wheel over the treadmill, AND you give instantaneous acceleration to the treadmill, and it's continuously trying to match the "wheelspeed" of the plane, it would seem the plane will not take off. If the treadmill was literally going 1 trillion miles an hour there may well be enough rolling resistance to keep that plane on the ground, no?!

2) Partial fantasy -
With a real plane on the treadmill that is blessed with instantaneous acceleration and that is continuously trying to match the "wheelspeed" of the plane, then at some point fairly quickly (like within a second of applying full power in the plane) the treadmill will be moving so fast that the wheels will explode or the hubs will melt or something, and the plane will not take off.

---side note: in both of the cases above, if the treadmill's control system is of the magical, zero nanosecond delay type, the plane will not at any time actually achieve any forward velocity, either. (Possibly a very important fact to some, but I could never grasp why.)

3) Reality other than still taking a rather odd interpretation of the question -
The odd interpretation is of course the whole reference to wheelspeed.
The original question posted by dirak stated "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)." From what viewpoint could "the plane speed" mean "the speed of the wheels over the treadmill?" If the plane was moving forward at 5 knots and the treadmill was moving at 50 knots, where would one need to be to think the speed of the plane was 50 knots?
Certainly standing off to the side, or in the tower, or in the nearest grain elevator, no one would say "that plane's going 55 knots!"
Inside the plane the pilot sure wouldn't think he was going 50 knots.
Even running(!) on the treadmill behind it, you wouldn't say the plane was going 55 knots. You may say something like "that plane's wheels are going 55 knots!" but as has been observed many times already, even that statement wouldn't be technically correct.
If you were atl5p, you would say "that plane's moving over this treadmill at 55 knots!!" but if we were to respond "true, but what's the speed of the plane?" he obviously wouldn't say... oh, right, I guess he would, wouldn't he?
Still, given that we're going to (mis)interpret the question... If the treadmill is of the non-ridiculous variety the plane will achieve forward velocity; whether it gets going fast enough to take off before the gear fails (or if the gear is semi-magical, before the plane slows to a stop) depends on how fast that treadmill can pick up speed. In this case, the plane either will or will not take off.

4) Reality -
If the question meant that the treadmill would match the speed of the plane as we generally understand the concept of speed, then the wheels would be spinning around twice as fast as normal when the plane takes off

atl5p, I'm calling you out. If you would like to disagree with any of these scenarios, please point out which one you're referring to when you do, and I will happily debate it with you, knowing that we are looking at the problem from the same angle. I don't even care which one you want to go after, I just think it would be refreshing to all be on the same page! Otherwise, I will take it that you agree with the outcomes stated above given the inputs stated above, and we can all consider the matter closed. If you would like to argue why it makes more sense to look at this from viewpoints 1, 2, or 3 than 4, or if you have a 5 or a 6 you want to throw in, I guess we could give that a shot also.

To be fair to everyone else who has been arguing this thing, I think they're all pretty much in the 3 or 4 camp (I'm a 4 myself, thanks for politely asking), and it seems to me that from viewpoint 4 the plane will definitely take off, and from 3 the question is unarguable since it depends on the rate of acceleration of the treadmill.
Now, if anyone wants to argue that 3 is the way to look at it, BUT the plane will definitely take off because rolling resistance is unaffected by wheelspeed, then that should be a whole new thread called "Does The Rolling Resistance Felt By An Airplane With Wheeled Landing Gear Increase With Velocity?" and I must say, I probably won't hang out in there, because now instead of a puzzling question, we have (IMHO) a rather dry but thank god completely realistic, unambiguous question that can be either debated or, hopefully, satisfactorily answered by people actually qualified to debate such matters!

*** Attention Atl5p ***
I get the feeling you tend to sort of not really read long posts very well/much/often, so I'm letting you know that I'm calling you out here.
AmazedByThis
QUOTE (AmazedByThis+Dec 6 2006, 09:07 PM)
That's like saying "we know X CAN in fact be greater than Y...if X is a larger number."  Logically, if the belt matches the "wheelspeed" of the plane (the speed relative to a point on the belt), the plane MUST have no groundspeed or airspeed!  The question is, can the treadbelt ever actually MATCH the "wheelspeed" of the plane?  That's what we're debating here!

QUOTE (Atl5p+Dec 6 2006, 09:13 PM)
Plenty of FlyBoys have stated that when you put my Tonka truck on a treadbelt, attatch a string and a digital scale, check the scale at various speeds, the weight shown on the scale will NEVER change because rolling resistance is not affected by speed.

That was their whole basis for 'It Flies'.

This thread, treadbelt matches wheelspeed (or rather, the speed the plane travels over the surface of the moveable treadbelt).  I don't know HOW the treadbelt does it, but it DOES.

Nowhere in this question does it ask 'Can the treadbelt KEEP UP with the plane'.  Nice try but...well, actually it's not even a very good try.

Do the math, A. If the "wheelspeed" is 50 knots and the treadmill's speed is 50 knots the plane can ONLY have an airspeed of 0 on a calm day. Therefore this WHOLE argument about rolling resistance must be about whether the treadmill can stop the plane... which it can only do by matching the wheelspeed of the plane. In other words, the argument has been about whether or not the treadmill can match the wheelspeed of the plane. Ya can't argue with that, can you?
By the way, if you make a new question called "Can a treadmill hold the airspeed of an airplane to 0 knots by matching its speed to the wheelspeed of the plane?" I promise never to go bug you in there. I know, I'd miss you too.
rethinker
Atl5p's mistake is the that he is not considering that the air and earth are not moving with the tread belt.
This lets the air plane use the air and travel over the belt. It will simply fly away leaving the belt behind.
Yes the wheels will spin a little faster than if it was simply taking off from a stationary runway.
Atl5p
QUOTE (AmazedByThis+Dec 7 2006, 06:28 PM)
That's funny... I was spending a bunch of time trying to figure out what belt speed would be required to hold back a Cessna 150, when I realized the same thing. I still maintain that there are only a few possible outcomes to this problem, based on how far you want to stretch reality.

*** Attention Atl5p ***
I get the feeling you tend to sort of not really read long posts very well/much/often, so I'm letting you know that I'm calling you out here.

The Four Possible Ways To Look At This Problem... I think

1) Complete fantasy (well, almost!) -
If you choose to endow your plane with magic immortal landing gear BUT curiously enough, even though it's magic, it still has rolling resistance that increases with the speed of the wheel over the treadmill, AND you give instantaneous acceleration to the treadmill, and it's continuously trying to match the "wheelspeed" of the plane, it would seem the plane will not take off. If the treadmill was literally going 1 trillion miles an hour there may well be enough rolling resistance to keep that plane on the ground, no?!

2) Partial fantasy -
With a real plane on the treadmill that is blessed with instantaneous acceleration and that is continuously trying to match the "wheelspeed" of the plane, then at some point fairly quickly (like within a second of applying full power in the plane) the treadmill will be moving so fast that the wheels will explode or the hubs will melt or something, and the plane will not take off.

---side note: in both of the cases above, if the treadmill's control system is of the magical, zero nanosecond delay type, the plane will not at any time actually achieve any forward velocity, either. (Possibly a very important fact to some, but I could never grasp why.)

3) Reality other than still taking a rather odd interpretation of the question -
The odd interpretation is of course the whole reference to wheelspeed.
The original question posted by dirak stated "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)." From what viewpoint could "the plane speed" mean "the speed of the wheels over the treadmill?" If the plane was moving forward at 5 knots and the treadmill was moving at 50 knots, where would one need to be to think the speed of the plane was 50 knots?
Certainly standing off to the side, or in the tower, or in the nearest grain elevator, no one would say "that plane's going 55 knots!"
Inside the plane the pilot sure wouldn't think he was going 50 knots.
Even running(!) on the treadmill behind it, you wouldn't say the plane was going 55 knots. You may say something like "that plane's wheels are going 55 knots!" but as has been observed many times already, even that statement wouldn't be technically correct.
If you were atl5p, you would say "that plane's moving over this treadmill at 55 knots!!" but if we were to respond "true, but what's the speed of the plane?" he obviously wouldn't say... oh, right, I guess he would, wouldn't he?
Still, given that we're going to (mis)interpret the question... If the treadmill is of the non-ridiculous variety the plane will achieve forward velocity; whether it gets going fast enough to take off before the gear fails (or if the gear is semi-magical, before the plane slows to a stop) depends on how fast that treadmill can pick up speed. In this case, the plane either will or will not take off.

4) Reality -
If the question meant that the treadmill would match the speed of the plane as we generally understand the concept of speed, then the wheels would be spinning around twice as fast as normal when the plane takes off

atl5p, I'm calling you out. If you would like to disagree with any of these scenarios, please point out which one you're referring to when you do, and I will happily debate it with you, knowing that we are looking at the problem from the same angle. I don't even care which one you want to go after, I just think it would be refreshing to all be on the same page! Otherwise, I will take it that you agree with the outcomes stated above given the inputs stated above, and we can all consider the matter closed. If you would like to argue why it makes more sense to look at this from viewpoints 1, 2, or 3 than 4, or if you have a 5 or a 6 you want to throw in, I guess we could give that a shot also.

To be fair to everyone else who has been arguing this thing, I think they're all pretty much in the 3 or 4 camp (I'm a 4 myself, thanks for politely asking), and it seems to me that from viewpoint 4 the plane will definitely take off, and from 3 the question is unarguable since it depends on the rate of acceleration of the treadmill.
Now, if anyone wants to argue that 3 is the way to look at it, BUT the plane will definitely take off because rolling resistance is unaffected by wheelspeed, then that should be a whole new thread called "Does The Rolling Resistance Felt By An Airplane With Wheeled Landing Gear Increase With Velocity?" and I must say, I probably won't hang out in there, because now instead of a puzzling question, we have (IMHO) a rather dry but thank god completely realistic, unambiguous question that can be either debated or, hopefully, satisfactorily answered by people actually qualified to debate such matters!

*** Attention Atl5p ***
I get the feeling you tend to sort of not really read long posts very well/much/often, so I'm letting you know that I'm calling you out here.

Look, I just see the OP as 'Can a treadbelt prevent a plane from flying'. I think that is what most people think when they hear it. Then they convince themselves that the plane will fly. Then that's when they start saying 'Well, the question says the plane moves, and it has speed from MY perspective standing right over there OFF that moving runway, because that would be just scary!

I notice on your #3, you say the plane .. well I'll quote you...
QUOTE
Inside the plane the pilot sure wouldn't think he was going 50 knots.
Even running(!) on the treadmill behind it, you wouldn't say the plane was going 55 knots. You may say something like "that plane's wheels are going 55 knots!" but as has been observed many times already, even that statement wouldn't be technically correct.

Remember, in the OP the plane is not on just a treadbelt...it's on a big ol'e runway, just one that can move. There is no mention of towers or trees or anything other than the moveable runway. I take speed to mean 'from the plane's perspective' ie the "plane's speed".
This is like a runner "I am running 5mph"...Plane says "I am running 100mph down this runway that just so happens is moving...can it keep me from flying, I don't know let's see".

ALso you have someone running behind the plane...I've said over and over 'You need to GET ON the treadbelt and stand still and watch the plane rush by you. Dobbins runway is 2 miles long, so sure this runway could be that long...get 'treadbelt' out of your head when there's a real plane going on in there.

For the record, all 'Plane moves because the question says it moves(through the air added in)' comments should be posted to the old original OP...that is where the 'IAS FlyBoys' can live.

I've said it so many times it's crazy, 'Sure if you use IAS the plane will fly ever time'...but when you pose a plane on a treadbelt and say it matches speed, I and most people think 'Can the treadbelt prevent flight?'. Then they say 'No'. Then they say 'The question says it moves, so it moves', and then they are locked in FlyBoy hell.

BTW the 'Point of reference for speed' was the whole point behind the Boy on a Railcar questions posed...Flyboys were pretty evenly divided on those and it proved a great point: it does matter where the speed of the plane is determined. That is the lesson we can all learn here. Requierments Specs can leave holes. That is the 'trick' to this question, if at all...it doesn't tell us how speed is measured. And it does matter, because the tredbelt CAN hold the plane to 0 IAS.

The bigger the engine, the heaver the plane and right there is where most of the rolling resistance comes from...then add velocity....so go get a more powerful engine without extra weight...ok, add more speed from treadbelt, no problem.

Does the OP give 'blowout' specs for the tires? No.
DOes the OP give a tower to stand in? No.
Does the OP tell you to stand to the side of the treadbelt? No.
And most importantly:
Does the OP tell us how the plane's speed is determined for the treadbelt to base it's speed from?

NO!

I think I've shown and most agree: When the plane's speed is measured as 'over the surface of the treadbelt', then the plane will never ever fly.

If flyboys want to bow to the alter of your omage just to save face, then so be it...Sure, the wheels may have to spin fast...that's OK. OP never asked if they would blow up...we assume they wont.

OP DOES say the treadbelt matches speed...I don't know how nor care....it's funny that this whole thing about treadbelt not being able to keep up with the plane's speed? I wonder why this wasn't used in the IAS version to prove it would fly? This is pure straw grasping, and it's should embarass flyboys who use it.

All said, I like what you've written...it is all fantisy, but I just feel the question asks if the treadbelt can hold the plane to 0 IAS by matching it's speed over the surface of the treadbelt...answer is yes.

You think the question askes if a plane moving through the air with a treadbelt matching it's airspeed, if that plane has airspeed er I mean will if fly? The answer to that question is also 'Yes'.

Good day, and thanks for the realization that it is physically possible. Now, would the 'bad' remarks be recended from my user ID? Probably not.
egnorant
QUOTE (Atl5p+Dec 8 2006, 03:42 AM)

All said, I like what you've written...it is all fantisy, but I just feel the question asks if the treadbelt can hold the plane to 0 IAS by matching it's speed over the surface of the treadbelt...answer is yes.

You think the question askes if a plane moving through the air with a treadbelt matching it's airspeed, if that plane has airspeed er I mean will if fly?  The answer to that question is also 'Yes'.

Good day, and thanks for the realization that it is physically possible.  Now, would the 'bad' remarks be recended from my user ID?  Probably not.

So are you answering the question "Yes" or "No'"?

I say "Yes" due to the planes speed as being relative to the ground.
I also note that the speed of the plane and the speed of the belt are both determined by the same device.

Bruce
Fynlcut
QUOTE (Atl5p+Nov 22 2006, 07:23 PM)
A plane is sitting on a moveable runway, like a treadbelt. The plane tries to take off in one direction, while the treadbelt moves in the opposite direction. The treadbelt has a control system to measure the plane's grounspeed over the runway, and the treadbelt matches this speed exactly.

Is the plane able to fly? Does it run up and fly?

I say "NO". What do you say, and why?

QUOTE
The treadbelt has a control system to measure the plane's grounspeed over the runway, and the treadbelt matches this speed exactly.

No it measures the plane's groundspeed. (over the runway, might as well be over the river and thru the woods cuz I'm flying this plane to grandma's house.)
Atl5p
I believe by now I have clarified: 'Plane groundspeed over (moving) runway' = 'Wheelspeed'.

There should be no more mis-inturpretations on this OP. This thread's OP will never fly.

The other 'OP' asks for the plane's speed...who's speed? The plane's...over the treadbelt is what the plane sees as it's 'speed'...YOU don't determine the plane's speed...the only one who can determine the plane's speed is the plane itself...ask the plane 'what is your speed'? Since he isn't flying (yet), he looks down at the runway and determine's his speed via his speed over runway. Then he tells the controler what his speed is and the controler adjusts accordingly.

A runner on a treadbelt runs in one direction, the treadbelt goes the other direction, he sets the treadbelt to 'match his speed exactly'...the runner's speed is how fast he's running on the treadbelt...he sets the treadbelt to this speed...the runner has no IAS....

Bruce, go spew your 'Plane moves through air....does it move through the air' BS on another thread....
Bloy
It all comes down to the question..
Are we going to accept atl5p's multiple reference point scenario?

In which case the plane will be limited to providing only a minimal amount of thrust
to remain below the threshold of resistance.

Oherwise, in the realm of reality, the PLANE THRUSTS THROUGH THE AIR AND TAKES OFF.
Fynlcut
QUOTE (Atl5p+Dec 8 2006, 02:48 PM)
I believe by now I have clarified: 'Plane groundspeed over (moving) runway' = 'Wheelspeed'.

There should be no more mis-inturpretations on this OP. This thread's OP will never fly.

The other 'OP' asks for the plane's speed...who's speed? The plane's...over the treadbelt is what the plane sees as it's 'speed'...YOU don't determine the plane's speed...the only one who can determine the plane's speed is the plane itself...ask the plane 'what is your speed'? Since he isn't flying (yet), he looks down at the runway and determine's his speed via his speed over runway. Then he tells the controler what his speed is and the controler adjusts accordingly.

A runner on a treadbelt runs in one direction, the treadbelt goes the other direction, he sets the treadbelt to 'match his speed exactly'...the runner's speed is how fast he's running on the treadbelt...he sets the treadbelt to this speed...the runner has no IAS....

Bruce, go spew your 'Plane moves through air....does it move through the air' BS on another thread....

You believe you have clarified the OP, but the OP was already clear. The planes ground speed over the treadbelt.

Regardless of what is between the plane and the ground.

GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!GROUNDSPEED!!

In the other OP, "Plane speed"= the entire plane not the wheels, not the tire stem cap, not the rock stuck in the tread. The plane in its majestic completeness. From nose to tail, wheel to rudder, wing tip to wing tip.

Turn the conveyor to match the movement of the plane. (both moving in the same direction) does the plane take off at 0mph?

I stand on a 10' platform. I jump, how far do I fall?

Atl5p goes to the airport to fly his plane. He opens the hanger door, and there sits a lone wheel, but what a wheel it is!!!
MikeMonty
QUOTE
A plane is sitting on a moveable runway, like a treadbelt.
The plane tries to take off in one direction, while the treadbelt moves in the opposite direction.
The treadbelt has a control system to measure the plane's grounspeed over the runway, and the treadbelt matches this speed exactly.

QUOTE (->
 QUOTE A plane is sitting on a moveable runway, like a treadbelt. The plane tries to take off in one direction, while the treadbelt moves in the opposite direction. The treadbelt has a control system to measure the plane's grounspeed over the runway, and the treadbelt matches this speed exactly.

I believe by now I have clarified: 'Plane groundspeed over (moving) runway' = 'Wheelspeed'.

My brain is wheeling now - can you unravel this stuff and explain to me by filling in the blanks:

If your CONTROL system is connected (working on, sensing, whatever) to a freewheeling "truck" that is being pulled along the conveyor by a car travelling on the ground beside the conveyor at 30 MPH, the conveyor belt surface is doing _____? MPH in the same/opposite* direction over the GROUND ground.

If your CONTROL system is connected to a freewheeling "truck" that is being pulled along the conveyor by a car travelling on the ground beside the conveyor at 60 MPH, the conveyor belt surface is doing _____? MPH in the same/opposite* direction over the GROUND ground.

* - delete as applicable

There you are - two simple little answers will dispel days of lost sleep and confusion.
egnorant
QUOTE (Atl5p+Dec 8 2006, 02:48 PM)
I believe by now I have clarified: 'Plane groundspeed over (moving) runway' = 'Wheelspeed'.

There should be no more mis-inturpretations on this OP.  This thread's OP will never fly.

The other 'OP' asks for the plane's speed...who's speed?  The plane's...over the treadbelt is what the plane sees as it's 'speed'...YOU don't determine the plane's speed...the only one who can determine the plane's speed is the plane itself...ask the plane 'what is your speed'?  Since he isn't flying (yet), he looks down at the runway and determine's his speed via his speed over runway.  Then he tells the controler what his speed is and the controler adjusts accordingly.

A runner on a treadbelt runs in one direction, the treadbelt goes the other direction, he sets the treadbelt to 'match his speed exactly'...the runner's speed is how fast he's running on the treadbelt...he sets the treadbelt to this speed...the runner has no IAS....

QUOTE
A plane is sitting on a moveable runway, like a treadbelt. The plane tries to take off in one direction, while the treadbelt moves in the opposite direction. The treadbelt has a control system to measure the plane's GROUNSPEED OVER THE RUNWAY, and the treadbelt matches this speed exactly.

Change this to:

A plane is sitting on a movable runway, like a treadbelt. The plane tries to take off in one direction, while the treadbelt moves in the opposite direction. The treadbelt has a control system to measure the plane's WHEELSPEED, and the treadbelt matches this speed exactly.

Is the plane able to fly? Does it run up and fly?

Once we make the "correction" of "grounspeed over the runway" to "wheelspeed"
Or even "speed over the runway"
I will answer NO!

QUOTE (->
 QUOTE A plane is sitting on a moveable runway, like a treadbelt. The plane tries to take off in one direction, while the treadbelt moves in the opposite direction. The treadbelt has a control system to measure the plane's GROUNSPEED OVER THE RUNWAY, and the treadbelt matches this speed exactly.

Change this to:

A plane is sitting on a movable runway, like a treadbelt. The plane tries to take off in one direction, while the treadbelt moves in the opposite direction. The treadbelt has a control system to measure the plane's WHEELSPEED, and the treadbelt matches this speed exactly.

Is the plane able to fly? Does it run up and fly?

Once we make the "correction" of "grounspeed over the runway" to "wheelspeed"
Or even "speed over the runway"
I will answer NO!

YOU don't determine the plane's speed...the only one who can determine the plane's speed is the plane itself...ask the plane 'what is your speed'?

No the controller measures the planes speed, read the question!
Same controller that measures and adjusts the belts speed!

AND in your runner on a treadbelt system you have moved the controller from the conveyor to the runner (plane).
Even then you are still reporting leg(wheel) speed to the conveyor.
I understand that wheelspeed and running speed can be manipulate so that it does not represent movement.

QUOTE
Bruce, go spew your 'Plane moves through air....does it move through the air' BS on another thread....

Aw Gee, can't I do several threads at once???

Bruce
gmilam
QUOTE (Fynlcut+Dec 8 2006, 10:38 AM)
Turn the conveyor to match the movement of the plane. (both moving in the same direction) does the plane take off at 0mph?

So, logically... when they put my pizza on that little conveyor belt that goes through the oven, my pizza isn't really moving because it doesn't have wheels.

Right?
egnorant
QUOTE (gmilam+Dec 8 2006, 06:04 PM)
So, logically... when they put my pizza on that little conveyor belt that goes through the oven, my pizza isn't really moving because it doesn't have wheels.

Right?

Even if it had wheels they would not be spinning.
I actually have a couple of these large conveyor ovens and they get used every day (except Thanksgiving, Christmas and half a day on Christmas Eve).
I have never had trouble explaining that the pizza moves from here to there.
Even though the pizza has no movement relative to what it is sitting on.

Pepperoni ON the cheese that was ON the sauce that was ON the crust that was ON the pan that was ON the conveyor that was moving.

Conveyor belt was moving both over and under hot air baffles until it had moved to the end where it was turned around and moved IN THE OPPOSITE DIRECTION.

ATL5Ps tactics can also be described as what we refer to as "Inquisition" tactics.
Truth has nothing to do with it...just inflict pain until you get an agreement and the pain will stop.
He doesn't realize that he is doing what we call "Rasslin' a hog in a waller".
Well this hog likes to rassle!!

Bruce

AmazedByThis
QUOTE (Atl5p+Dec 8 2006, 03:42 AM)
Look, I just see the OP as 'Can a treadbelt prevent a plane from flying'.  I think that is what most people think when they hear it.  ...
Remember, in the OP the plane is not on just a treadbelt...it's on a big ol'e runway, just one that can move.  There is no mention of towers or trees or anything other than the moveable runway.  I take speed to mean 'from the plane's perspective' ie the "plane's speed".
This is like a runner "I am running 5mph"...Plane says "I am running 100mph down this runway that just so happens is moving...can it keep me from flying, I don't know let's see".
...
I've said it so many times it's crazy, 'Sure if you use IAS the plane will fly ever time'...but when you pose a plane on a treadbelt and say it matches speed, I and most people think 'Can the treadbelt prevent flight?'.  Then they say 'No'.  Then they say 'The question says it moves, so it moves', and then they are locked in FlyBoy hell.
...
I think I've shown and most agree: When the plane's speed is measured as 'over the surface of the treadbelt', then the plane will never ever fly.
...
All said, I like what you've written...it is all fantisy, but I just feel the question asks if the treadbelt can hold the plane to 0 IAS by matching it's speed over the surface of the treadbelt...answer is yes.

You think the question askes if a plane moving through the air with a treadbelt matching it's airspeed, if that plane has airspeed er I mean will if fly?  The answer to that question is also 'Yes'.

Good day, and thanks for the realization that it is physically possible.  Now, would the 'bad' remarks be recended from my user ID?  Probably not.

I just looked at the feedback section, and it appears I cannot edit what I wrote. However, I did attempt to add a positive feedback that went like this.
QUOTE
Update: I'm revising my opinion of Atl5p.  It seems by the time I started following the posts he was involved in, the debate between him and other members had devolved into minutia and close-mindedness all around, but he is willing to hear out and evaluate others' opinions.

Of course, when I hit submit, I got the following from Physorg.
QUOTE (->
 QUOTE Update: I'm revising my opinion of Atl5p.  It seems by the time I started following the posts he was involved in, the debate between him and other members had devolved into minutia and close-mindedness all around, but he is willing to hear out and evaluate others' opinions.

Of course, when I hit submit, I got the following from Physorg.
Sorry, an error occurred. If you are unsure on how to use a feature, or don't know why you got this error message, try looking through the help files for more information.

The error returned was:
Sorry, you cannot rate the same member within 1 week period.

So in a week I will submit that feedback.

QUOTE
Look, I just see the OP as 'Can a treadbelt prevent a plane from flying'.

If you're saying 'given enough power, could a treadbelt prevent a plane from flying?' then I totally agree with you that the answer would be yes - that is, the plane would not fly. In the possible scenarios I outlined above, that would be under #3, and I think that the treadmill could overwhelm the structural integrity of the gear.

As for the runner on a treadmill saying "I am running 5 mph" I would think that if you asked him, "yes, but how fast are you actually moving?" he would most likely say "well, I'm not really going anywhere!". Also, when you say, "I take speed to mean 'from the plane's perspective' ie the "plane's speed"" I take it to mean the same thing, but I still think that from the plane's perspective the IAS is the deal. As I said, the pilot would obv look at his airspeed indicator to tell the tower his speed, and even if you gave the plane a brain, the only sensory device it has is to tell it how fast it's moving is the pitot tube/static port/airspeed indicator. I hope you at least agree with the following thought: if a plane touched down at 90 knots on an icy runway and the pilot locked the brakes, no one who hadn't read these threads would ever think "That plane's going 0mph but it's still moving!!" However, I readily concede that these are just differences in interpretation of the question, not in the answers.

Regarding landing gear failure, you say "OP never asked if they would blow up...we assume they wont." Why not? Personally, I think you oughtta go with that one. It's pretty inarguable that rubber tires heat up and fail at high enough speeds.
As for people who still claim to not understand what you mean when you say "wheelspeed" or who say "this question could not possibly mean wheelspeed" or "I know that the original question meant groundspeed (or airspeed) not wheelspeed" I think that's just rude, or they're really incredibly stupid (note:unless they happen to be the original poster from the original thread, or the original poster of this thread - oh wait, that's you; you probably know what you meant!)
Anyways, good luck with these other guys; if I were you I wouldn't even respond to anyone who wants to argue about what you meant(!) when you rephrased this question to start this thread.

ON ANOTHER NOTE -
For those of you who have been following these threads just for the Jerry Springer-esque atmosphere, have I got something for you! Go to the "Relativity, Quantum Mechanics, New Theories" forum and check out the "Do you want stronger moderation here ?, Time to talk about it." thread. It starts out sane but within like five posts goes all to hell. "zephyr" and "alphanumeric" really don't like each other. Really. Also, zephyr has the following stats -
Posts: 5135
Positive Feedback: 40%
Feedback Score: -62

Positive: 34 (22 unique)
Negative: 96 (33 unique)
This guy's got people that give him negs every 7 days! Some other dude, "Pupamancur", has 73 feedbacks(?) and a warn (whatever that is) of 80%. Those people do not like each other. These threads over here are downright friendly!!!
MikeMonty
QUOTE (AmazedByThis+Dec 8 2006, 08:10 PM)
Anyways, good luck with these other guys; if I were you I wouldn't even respond to anyone who wants to argue about what you meant(!) when you rephrased this question to start this thread.

Mine is a genuine question, honest! I want to strip away all the semantics and get sight of a simple model of what's going on - too much time spent analysing a badly worded question and then trying to come to a consensus on what he meant. tongue-in-cheek or otherwise.

I'll post it again because it's in danger of getting lost. (though that may be no bad thing!)
Maybe if ATL5P would fill in the blanks.......?

If your CONTROL system is connected (working on, sensing, whatever) to a freewheeling "truck" that is being pulled along the conveyor by a car traveling on the ground beside the conveyor at 30 MPH, the conveyor belt surface is doing _____? MPH in the same/opposite* direction over the GROUND ground.

If your CONTROL system is connected to a freewheeling "truck" that is being pulled along the conveyor by a car traveling on the ground beside the conveyor at 60 MPH, the conveyor belt surface is doing _____? MPH in the same/opposite* direction over the GROUND ground.

* - delete as applicable

There you are - two simple little answers will dispel days of lost sleep and confusion.
Atl5p
QUOTE (MikeMonty+Dec 8 2006, 04:21 PM)
Mine is a genuine question, honest! I want to strip away all the semantics and get sight of a simple model of what's going on - too much time spent analysing a badly worded question and then trying to come to a consensus on what he meant. tongue-in-cheek or otherwise.

I'll post it again because it's in danger of getting lost. (though that may be no bad thing!)
Maybe if ATL5P would fill in the blanks.......?

If your CONTROL system is connected (working on, sensing, whatever) to a freewheeling "truck" that is being pulled along the conveyor by a car traveling on the ground beside the conveyor at 30 MPH, the conveyor belt surface is doing _____? MPH in the same/opposite* direction over the GROUND ground.

If your CONTROL system is connected to a freewheeling "truck" that is being pulled along the conveyor by a car traveling on the ground beside the conveyor at 60 MPH, the conveyor belt surface is doing _____? MPH in the same/opposite* direction over the GROUND ground.

* - delete as applicable

There you are - two simple little answers will dispel days of lost sleep and confusion.

TreadbeltSpeed = Wheelspeed + 30

TreadbeltSpeed = Wheelspeed + 60

That's my best guess...but I won't stand by it, you can't quote me on it, and I immediatly disagree with it!

and I do mean ROTFLOL
MikeMonty
QUOTE (Atl5p+Dec 8 2006, 09:45 PM)
TreadbeltSpeed = Wheelspeed + 30

TreadbeltSpeed = Wheelspeed + 60

That's my best guess...but I won't stand by it, you can't quote me on it, and I immediatly disagree with it!

and I do mean ROTFLOL

Dammit!

Condemned to days of lost sleep and confusion.

Ah well, at least I know where we stand (roll, measure from, whatever )
Benny
QUOTE
I just looked at the feedback section, and it appears I cannot edit what I wrote.  However, I did attempt to add a positive feedback that went like this.
QUOTE (->
 QUOTE I just looked at the feedback section, and it appears I cannot edit what I wrote.  However, I did attempt to add a positive feedback that went like this.Update: I'm revising my opinion of Atl5p.  It seems by the time I started following the posts he was involved in, the debate between him and other members had devolved into minutia and close-mindedness all around, but he is willing to hear out and evaluate others' opinions.
Your existing feedback is an incredibly accurate description of Atl5p, why in the world would you change it?

QUOTE
Anyways, good luck with these other guys; if I were you I wouldn't even respond to anyone who wants to argue about what you meant(!) when you rephrased this question to start this thread.
"Do as I mean not as I say?" No, if he had said "Oops, I meant wheelspeed, not groundspeed." or simply asked "Can an unlimited conveyor hold back a plane?" in the first place (no interpretation problems with that one) it would have been fine; instead he tried to redefine the English language to avoid admitting his mistake (classic Atl.)

QUOTE (->
 QUOTE Anyways, good luck with these other guys; if I were you I wouldn't even respond to anyone who wants to argue about what you meant(!) when you rephrased this question to start this thread.
"Do as I mean not as I say?" No, if he had said "Oops, I meant wheelspeed, not groundspeed." or simply asked "Can an unlimited conveyor hold back a plane?" in the first place (no interpretation problems with that one) it would have been fine; instead he tried to redefine the English language to avoid admitting his mistake (classic Atl.)

As for the runner on a treadmill saying "I am running 5 mph" I would think that if you asked him, "yes, but how fast are you actually moving?" he would most likely say "well, I'm not really going anywhere!".  Also, when you say, "I take speed to mean 'from the plane's perspective'.....
All of these perfectly obvious and rational examples have been pointed out again and again. He doesn't have an answer for any of them.

QUOTE
ON ANOTHER NOTE -
For those of you who have been following these threads just for the Jerry Springer-esque atmosphere
....
Those people do not like each other.  These threads over here are downright friendly!!!
Haven't looked over there much, but Zephir deserves it. It's not the "Jerry Springer" atmosphere anyway, it's the baloney that Atl comes up with that provide the entertainment.
MikeMonty
QUOTE (Atl5p+Dec 8 2006, 09:45 PM)
TreadbeltSpeed = Wheelspeed + 30

TreadbeltSpeed = Wheelspeed + 60

That's my best guess...but I won't stand by it, you can't quote me on it, and I immediatly disagree with it!

and I do mean ROTFLOL

"Ask him to explain his assertions - good for a laugh - his choices are:
1. Ignore
2. Feign misunderstanding
3. Abuse
4. Admit ignorance and ask you to explain to him whereupon he will do one of the above again"

I think I need to invent a new category of response - what shall we describe this as - how about:
5. Bizarre non-sequitur ?
N.U.R
You know I,ve been wondering....have all of you never been in an Air Craft?

IT CANT TAKE OFF~
Fynlcut
I've been in them, I've piloted them, I've worked on them, I use to build parts for the big ones, now I check the quality on the parts of the big ones.

I've built and flown (repaired and flown again) models since the age of 8. I currently fly hang gliders for fun.

Yep I've been in, around, under, over, beside and on top of many of them.

He said the plane has ground speed, at that point you can move the conveyor opposite 100X the speed the plane is going and it still has ground speed.

I'm standing on a 10' tall platform. I jump, how far do I fall?
MikeMonty
QUOTE (N.U.R+Dec 9 2006, 02:05 AM)
You know I,ve been wondering....have all of you never been in an Air Craft?

IT CANT TAKE OFF~

What kind of logic is that?

I've never been in a Titan rocket but I understand the principles!

Why argue this any further anyway, when the original poster has essentially said that the question has deliberately movable goalposts?

He says:
"TreadbeltSpeed = Wheelspeed + 30
TreadbeltSpeed = Wheelspeed + 60
That's my best guess...but I won't stand by it, you can't quote me on it, and I immediatly disagree with it!"
N.U.R
QUOTE (Fynlcut+Dec 9 2006, 02:28 AM)

I'm standing on a 10' tall platform. I jump, how far do I fall?

Is there a rope pulling you up at the same rate your falling? Cant make an example then take out the main point

And as for what kind of arument, LIFT, air under wing to lift, need go fasty fasty you know?

180kmph for a 747 6 btw
MikeMonty
QUOTE (N.U.R+Dec 9 2006, 12:52 PM)
Is there a rope pulling you up at the same rate your falling? Cant make an example then take out the main point

And as for what kind of arument, LIFT, air under wing to lift, need go fasty fasty you know?

180kmph for a 747 6 btw

I said what kind of LOGIC.

And yes you "need go fasty fasty"
Point of my argument (and all other "will flyers") is nothing is stopping it from going "fasty fasty"

need go thinky thinky maybe?
NoCleverName
Well, I'm back from skiing ... some powder, mind you, and I see you all are still wasting your time with Atl5p.

The plane flies; the control system controls the belt, not the plane. The belt can do what it wants as the plane moves forward under its own power unhindered by rolling resistance which (even if it did increase) never amounts to enough to hold back the plane.

There is no reason to argue about what speed the plane has: it has whatever speed is commensurate with the throttle setting. The belt can't do anything about it no matter how the belt speed is determined. All the belt can do is spin the wheels faster and faster to no avail.

If you want to argue "a trillion miles an hour will stop the plane", well then it would stop the belt, too, because its mechanism must be made up of wheels as well and they would lock up, too.

Since it's clear that "wheel rolling resistance" can't stop the plane before it gets to takeoff speed, exactly what are you proposing that will?
rethinker
NoCleverName
You must of run into some good powder up on the mountain, because that is as clear as I think anyone has made this thread.
It is simple physics.
The plane is one in itself and what it takes off from does not matter.
The song Flyaway by John Denver was a beautiful song! I think that was the title.
egnorant
QUOTE (N.U.R+Dec 9 2006, 12:52 PM)
Is there a rope pulling you up at the same rate your falling? Cant make an example then take out the main point

And as for what kind of arument, LIFT, air under wing to lift, need go fasty fasty you know?

180kmph for a 747 6 btw

If there is a rope that is pulling up at the same speed you are falling....
Then you are not falling!
The only time this can exist is when both are at 0 mph (ft/sec or whatever).
I currently have a force trying to make me fall and I have a chair that is providing a force to preventing this fall....total speed of my fall....0 mph!!

Bruce
Fynlcut
What does fall mean?? Choose your meaning.

QUOTE
Main Entry: 1fall
Pronunciation: 'fol
Function: verb
Inflected Form(s): fell  /'fel/; fall·en  /'fo-l&n/; fall·ing
Etymology: Middle English, from Old English feallan; akin to Old High German fallan to fall and perhaps to Lithuanian pulti
intransitive verb
1 a : to descend freely by the force of gravity b : to hang freely <her hair falls over her shoulders> c : to drop oneself to a lower position <fell to his knees> d : to come or go as if by falling <darkness falls early in the winter>
2 : to become born -- usually used of lambs
3 a : to become lower in degree or level <the temperature fell 10°> b : to drop in pitch or volume <their voices fell to a whisper> c : ISSUE 1a, b <wisdom that fell from his lips> d : to become lowered <her eyes fell>
4 a : to leave an erect position suddenly and involuntarily <slipped and fell on the ice> b : to enter as if unawares : STUMBLE, STRAY <fell into error> c : to drop down wounded or dead; especially : to die in battle d : to suffer military capture <after a long siege the city fell> e : to lose office <the party fell from power> f : to suffer ruin, defeat, or failure <the deal fell through>
5 : to commit an immoral act; especially : to lose one's chastity
6 a : to move or extend in a downward direction <the land falls away to the east> b : SUBSIDE, ABATE <the wind is falling> c : to decline in quality, activity, or quantity <production fell off> d : to lose weight -- used with off or away e : to assume a look of shame, disappointment, or dejection <his face fell> f : to decline in financial value or price <stocks fell sharply>
7 a : to occur at a certain time <her birthday falls on a Monday this year> b : to come by chance <a job that fell into his hands> c : to come or pass by lot, assignment, or inheritance : DEVOLVE <it fell to him to break the news> d : to have a certain or proper position, place, or station <the accent falls on the second syllable>
8 : to come within the limits, scope, or jurisdiction of something <this word falls into the class of verbs>
9 : to pass suddenly and passively into a state of body or mind or a new state or condition <fall asleep> <fall in love>
10 : to set about heartily or actively <fell to work>
11 : STRIKE, IMPINGE <music falling on the ear>
transitive verb : FELL 1

Atl5p
QUOTE (MikeMonty+Dec 9 2006, 05:56 AM)
What kind of logic is that?

I've never been in a Titan rocket but I understand the principles!

Why argue this any further anyway, when the original poster has essentially said that the question has deliberately movable goalposts?

He says:
"TreadbeltSpeed = Wheelspeed + 30
TreadbeltSpeed = Wheelspeed + 60
That's my best guess...but I won't stand by it, you can't quote me on it, and I immediatly disagree with it!"

You are a liar and a mis-quoter....piece of she-at

Remember the original question, to which he quotes my responce:
QUOTE
My brain is wheeling now - can you unravel this stuff and explain to me by filling in the blanks:

If your CONTROL system is connected (working on, sensing, whatever) to a freewheeling "truck" that is being pulled along the conveyor by a car travelling on the ground beside the conveyor at 30 MPH, the conveyor belt surface is doing _____? MPH in the same/opposite* direction over the GROUND ground.

If your CONTROL system is connected to a freewheeling "truck" that is being pulled along the conveyor by a car travelling on the ground beside the conveyor at 60 MPH, the conveyor belt surface is doing _____? MPH in the same/opposite* direction over the GROUND ground.

* - delete as applicable

There you are - two simple little answers will dispel days of lost sleep and confusion.

Obviously, since there is a car travelling on the solid ground beside the treadbelt, and this car is in the act of 'towing' the truck which is on the treadbelt, and since the treadbelt is matching the wheelspeed of the Truck on the treadbelt, but that Truck is being pulled by a Car on solid ground, and that Car's speed is set as a constant in the question as either 30mph or 60mph, then the treadbelt will ALWAYS spin at 30mph/60mph plus the wheelspeed reading of the Truck on the treadbelt.

My answer to this question, and this question itself, has absolutly nothing to do with an airpowered vehicle with it's entire weight pressing down into the surface of a treadbelt...

I really hope the GOOD people on this tread DO realize this.

I hope they realize the misquoting by Mike Monty

I hope they understand that Mike has absolutly lost credability with me, he is now in the same catagory as Bloy....undeserving of my attention any longer....have fun debating yourselves guys...

Keep in mind that MikeMonte 'cannot argue' with the fact that when a freewheeling vehicle is set upon a treadbelt, and a scale is attatched to the vehicle, and then the treadbelt speed is increased to various set speeds, that scale will show an increasing Force/Weight dependant on the speed of the treadbelt. The faster the treadbelt spins, the more Rolling Resistance Force is produced-pushing the vehicle 'backwards' with the treadbelt's direction, with an ever increasing force, due to treadbelt's speed and the rolling resistance of the vehicle's tires.

Then after a couple of days he says 'It is a well known fact that there is nothing that a treadbelt can do via rolling tires, to make an opposing force on the plane'.

He is pure garbage...he is 'junk science'.
MikeMonty
QUOTE (Atl5p+Dec 11 2006, 04:49 PM)
You are a liar and a mis-quoter....piece of she-at

Nice!
The Muppets never talked like that before!
I trust Gonzo, that you can explain how I've lied and mis-quoted you?

Also, what is all this stuff about "since the treadbelt is matching the wheelspeed of the Truck on the treadbelt, but that Truck is being pulled by a Car.." etc come from

I asked a simple question, you gave me gibberish for an answer the first time round and gibberish this time round.

At least the rest of the forum are getting a laugh!

I don't remember saying:
"is a well known fact that there is nothing that a treadbelt can do via rolling tires, to make an opposing force on the plane'."
I DO remember
"With a few notable exceptions it is agreed that both of these factors are constants"

If this is what you are referring to then you are mis-quoting.

ps I don't understand what "she-at" is can you explain?
Guest_michael
This is perhaps the silliest debate I've ever come across. Some of the posters seem to think that it is the groundspeed of the aircraft that enables it to fly, rather than the airspeed! Keep in mind that the aircraft rests on wheels, not fixed blocks. ;-)

Quite obviously, if an aircraft had perfect, frictionless wheelbearings, the treadmill could go as fast as it liked and the plane would still remain motionless while its engines were off. Once thrust is applied, the aricraft would move just as it does on an ordinary airstrip.

Adding real world friction only changes matters slightly. Only a very small fraction of the energy in the moving runway is transferred to the aircraft via the wheel bearings.

There is a similar problem often posed having to do with a car driving up a ramp into a moving truck- some of you may recall a television ad for the Triumph TR-7 that performed that very trick. If you think about that you'll see it's the same problem in reverse.
Bloy
QUOTE (MikeMonty+Dec 11 2006, 05:06 PM)
Nice!
The Muppets never talked like that before!
I trust Gonzo, that you can explain how I've mis-quoted you?

Atl5p can't explain...
He only ignores that the plane has thrust relative to the air.
A while back he tried to explain his reasoning by ruling out everything.
...he said there was nothing but the plane and belt, all in their separate universe.
How farfetched! ..just to try and prove his hapless point.
NoCleverName
QUOTE (Atl5p+Dec 11 2006, 04:49 PM)
The faster the treadbelt spins, the more Rolling Resistance Force is produced-pushing the vehicle 'backwards' with the treadbelt's direction, with an ever increasing force, due to treadbelt's speed and the rolling resistance of the vehicle's tires.

Too bad the "increasing rolling resistance" is as pathetically weak a force against the plane as is your arguments to convince people otherwise.

And you actually can't see why the towed truck experiment is exactly the same as the plane? I'll tell you what, let's make it a glider instead and we'll load it up with a few more tons of pig iron to simulate the engines it doesn't have.

As far as "junk science" goes, since you are now the world's foremost expert in dynamics, someday you really ought to treat us all to what you think really happens. "scientifically", when the pilot pushes those throttles forward all the way.

P.S. After you're through with your apprenticship here, they need more scientifically educated bodies over in the 9/11 conspiracy threads.
AmazedByThis
Guest_Michael,
Your statement is true, well thought out, and rooted in reality, and would suit you well in the other post about the plane on the treadmill. However, if you'll see my post a few days ago where I break out the possible ways to interpret the question on this thread, you will see that we are way past the obvious answer (with which I agree by the way) and are into hypotheticals in a big way. When you say
QUOTE
Only a very small fraction of the energy in the moving runway is transferred to the aircraft via the wheel bearings.

That is precisely what some of us are arguing about. Given a ridiculously high treadmill speed, does that fraction get large enough to stop the plane? Some people argue that rolling resistance does not increase with speed.

Hey Mike and Bloy!
Here's my question for you.
Take a single engine Cessna, like a 172. Put it on the moving runway, and within one second of powering it up, have the runway go in the opposite direction 1 million miles per hour. Do you think the plane will still take off?

NoCleverName,
you say
QUOTE (->
 QUOTE Only a very small fraction of the energy in the moving runway is transferred to the aircraft via the wheel bearings.

That is precisely what some of us are arguing about. Given a ridiculously high treadmill speed, does that fraction get large enough to stop the plane? Some people argue that rolling resistance does not increase with speed.

Hey Mike and Bloy!
Here's my question for you.
Take a single engine Cessna, like a 172. Put it on the moving runway, and within one second of powering it up, have the runway go in the opposite direction 1 million miles per hour. Do you think the plane will still take off?

NoCleverName,
you say
Since it's clear that "wheel rolling resistance" can't stop the plane before it gets to takeoff speed, exactly what are you proposing that will?

Now I have been following this for a few weeks (I realize it's been going on longer) and I still haven't seen what makes it clear. This page (sorry. physorg won't let me link it)
www.ae.go.dlr.de/dyn/research/tyre_soil/tyre_soil.html
is by a company that, among other things "investigates the dynamics of aircraft on ground and the calculation of aeroelastic phenomena on the basis of multibody dynamics." The page I'm citing is primarily about soft-soil landings, but there is a graph midway down on the left side that shows rolling resistance on firm surfaces beginning to increase dramatically with speed. It seems also to be a well known fact that rubber pneumatic tires can overheat and fail if they run significantly faster than they are rated for.

Goodyearaviation.com has the following bits of info on its site.
QUOTE
an aircraft tire typically runs at 32 percent deflection, while a car tire runs at only 11 percent deflection...
The higher deflection that aviation tires use is designed to carry high loads while limiting heat generation from sidewall flexing to an acceptable level. However, that means that small amounts of additional deflection bring rapidly increasing heat generation and thus, rapidly diminishing tire durability.

I am inferring from that statement, as well as from common sense, that aircraft tires are designed to operate in a very specific envelope. If you think about aviation tire design from the standpoint of an engineer, (s)he is trying to balance weight and cost vs. durability and grip. Looking at the FAQs on the goodyear site, it is clear that airplane tires are designed very differently than auto tires. What isn't stated, but I believe is safe to assume, is that aircraft tires have been designed to run at high speeds for no than a few miles at a time. Now, if that Cessna 172 makes a 45 second successful takeoff run over a treadmill that is going one million miles per hour, the wheels will have traveled(over the moving surface of the runway obv, NOT actual distance) 12,500 miles. In 45 seconds. Are we really to believe that these tires could handle it?

Dunlop's aviation division has the following nugget on their page about care and inspection.
QUOTE (->
 QUOTE an aircraft tire typically runs at 32 percent deflection, while a car tire runs at only 11 percent deflection...The higher deflection that aviation tires use is designed to carry high loads while limiting heat generation from sidewall flexing to an acceptable level. However, that means that small amounts of additional deflection bring rapidly increasing heat generation and thus, rapidly diminishing tire durability.

I am inferring from that statement, as well as from common sense, that aircraft tires are designed to operate in a very specific envelope. If you think about aviation tire design from the standpoint of an engineer, (s)he is trying to balance weight and cost vs. durability and grip. Looking at the FAQs on the goodyear site, it is clear that airplane tires are designed very differently than auto tires. What isn't stated, but I believe is safe to assume, is that aircraft tires have been designed to run at high speeds for no than a few miles at a time. Now, if that Cessna 172 makes a 45 second successful takeoff run over a treadmill that is going one million miles per hour, the wheels will have traveled(over the moving surface of the runway obv, NOT actual distance) 12,500 miles. In 45 seconds. Are we really to believe that these tires could handle it?

Dunlop's aviation division has the following nugget on their page about care and inspection.
G. Bulges (Tyre Failure) (Ref. Fig. 306)
(1) A bulge in the tread or sidewall can occur if there is a separation of tyre
components (for example, because the tyre was too hot). A tyre bulge could occur
if an aircraft is taxied quickly over a long distance.

Emphasis mine on "taxied" of course, but I'll bet by 'quickly' they aren't talking more than 3/4 of the plane's rotation speed and by 'long distance' I'll bet they're not talking about longer than is generally possible at an airport, a couple of miles at most. Even if they do mean longer than that, they probably aren't talking about 25 miles, let alone fifty. Fifty miles in 45 seconds is 4000 miles an hour.

Am I saying that is a realistic speed for the treadmill to be capable of acheiving? Hell no. But if we read the question the way you and I actually read the question, such that the treadmill is going twice the ias at takeoff, I wonder what the cost would be in constructing a 3000ft long treadmill capable of going 150 and supporting a light plane?

As a related question, if you mounted an aircraft tire on an aircraft axle over a skinny treadmill like this -0- (top down ascii-cad diagram!), put a few hundred pounds of load on it, and set up strain gauges to the rear of the axles to measure rearward force, are y'all really contending that the gauges would indicate the same amount at .1 mph, 25 mph, and 500 mph?
Atl5p
Amazed, yes that is what they HAVE said...no matter how fast you spin that treadbelt, the 'weight' on the scale will be exactly the same no matter what the speed.

No Clever Anything....failure to answer the above question from Amazed will be an admition of defeat.... ;-)

Oh, BTW here's another one that says Rolling Resistance Force will increase with treadbelt velocity:

http://www.cvdc.org/recent_papers/PopovColeCebonWinkler.pdf

graph on page 11...as speed increases so does the "Measured rolling resistance coefficient Fx/Fz"...basically they took a tire, straped a scale to it, and put it on a treadbelt, and then they took measurements as they set the speed of the treadbelt to various speeds....guess what, the faster the belt spins, the greater the 'measured rolling resistance...'

But the FlyBoys will still tell you: Rolling Resistance is constant with speed....put a wheeled vehicle on a treadbelt, tie it to a scale, then increase the treadbelt speed...the scale will ALWAYS measure the same force...ALWAYS...that is because Rolling Resistance Force is NOT speed dependant.

They will say this even after reading the research...what does that tell you?
NoCleverName
QUOTE
QUOTE (->
 QUOTE Since it's clear that "wheel rolling resistance" can't stop the plane before it gets to takeoff speed, exactly what are you proposing that will? Now I have been following this for a few weeks (I realize it's been going on longer) and I still haven't seen what makes it clear.

I believe as an example somewhere I calculated a B-777 with engine thrust of some 800,000 N weighing in at 300,000 kg supported on 12 tires of CRR of 0.03 would create a resistance of about 90,000 N. Now the CRR of 0.03 is probably way too high, but you can see the engines easily overpower by a factor of 10.

For the rolling resistance to equal thrust, the CRR would have to be more like 0.3 --- effectively the same as having the brakes on.

So as you can see ... clearly not enough.

QUOTE
going one million miles per hour, the wheels will have traveled(over the moving surface of the runway obv, NOT actual distance) 12,500 miles. In 45 seconds. Are we really to believe that these tires could handle it?

Why would you put up real-world tire specifications against a fantasy-land runway? If you want a million mph runway, then I'm going to have to insist on having tires fully capable of running on them --- and I mean good tires, too, with any small CRR I want to match the any-speed-you-want runway.

QUOTE (->
 QUOTE going one million miles per hour, the wheels will have traveled(over the moving surface of the runway obv, NOT actual distance) 12,500 miles. In 45 seconds. Are we really to believe that these tires could handle it?

Why would you put up real-world tire specifications against a fantasy-land runway? If you want a million mph runway, then I'm going to have to insist on having tires fully capable of running on them --- and I mean good tires, too, with any small CRR I want to match the any-speed-you-want runway.

f you mounted an aircraft tire on an aircraft axle over a skinny treadmill like this -0- (top down ascii-cad diagram!), put a few hundred pounds of load on it, and set up strain gauges to the rear of the axles to measure rearward force, are y'all really contending that the gauges would indicate the same amount at .1 mph, 25 mph, and 500 mph?

No one is insisting on the "same" amount, just a relatively modest number. That's not to say you not need more horsepower to go faster. The real-world CRR is definitely going to vary with speed --- however, as long as we stay within the design of the materials, the force shouldn't be prohibitive.

Atl5P's general strategy is to take the problem outside of where it was staged to an extreme fantasy world, and then attempt to say what's true in fantasy land must be true in the real world, too. Don't fall for that trap (like you did when you looked up the tire manufactures spec's to see if their tires would run at a million mph).
NoCleverName
QUOTE (Atl5p+Dec 11 2006, 07:29 PM)
Amazed, yes that is what they HAVE said...no matter how fast you spin that treadbelt, the 'weight' on the scale will be exactly the same no matter what the speed.

No Clever Anything....failure to answer the above question from Amazed will be an admition of defeat....  ;-)

I have no problem with the fact that the working "rule of thumb" that CRR is constant at speed will eventually break down. Nor does anyone else. Of course CRR varies with speed. But the fact that CRR is generally such a small number no matter what speed you are running, it's far more convenient to say it's a constant. In other words, in most physical problems there is nothing to be gained by using the exact figure.

It's the same for the plane problem --- the CRR isn't going to get big enough over the speed range in question to be a problem. Like I said before, it can't just go up, it has to go way, way up by a factor of 10-to-30 --- essentially be the same as if the wheel had its brakes on --- not very realistic.

Fortunately we now have you pinned to the rolling resistance rather than the magic control system. At least that's scientific, and that alone kills your argument. Now if we can just get you out of the fantasy land of the belt-that-can-go-faster-than-fast, we're all set.
MikeMonty
In the words of the incisive Mr Fynlcut:

QUOTE (Fynlcut+Dec 7 2006, 08:32 PM)

QUOTE
Because the heat transfer to the environment increases slower than heat generation, a gradual increase of tyre temperature appears. Higher temperature will reduce the hysteresis losses and increase the inflation pressure. Due to these effects the rolling resistance decrease (i.e. for a 385/65 R 22.5 tyre with 25 kN load and a final speed of 60 km/h, the inflation pressure increases from 600 to 678 kPa and the rolling resistance force decreases from 172 to 127 N [6]).

Wait, what is it, it increases, or decreases?

Oh Look!
I can argue!

Unlike you I can revise my opinions - thats allowed and in some cases is a demonstration of sanity.
Bloy
Isn't there the theory that a plane COULD lift itself into the air simply by having enough thrust from the engine to make the pressure differences between the high and low side of the wing large enough to offset the weight? I think this is real given an unusually high thrust and position of power source.
...although deemed highly inefficient, I believe this is possible.

If so, then the plane after an enormous output would begin lifting into the air while the belt is spinning at an unimaginable and rediculous speed.

The plane flys!
NoCleverName
Ya, the harrier does this, F-22 raptor, high-lift planes.

Just avoids the problem.

Speaking of avoiding the problem, ol' Atl5p is making a classic troll move of forking the problem to a new thread. Let's just nobody answer it.
Bloy
QUOTE (Bloy+Dec 11 2006, 08:13 PM)
Isn't there the theory that a plane COULD lift itself into the air simply by having enough thrust from the engine to make the pressure differences between the high and low side of the wing large enough to offset the weight? I think this is real given an unusually high thrust and position of power source.
...although deemed highly inefficient, I believe this is possible.

If so, then the plane after an enormous output would begin lifting into the air while the belt is spinning at an unimaginable and rediculous speed.

The plane flys!

I pity the pilot once the plane's "glue" to the belt is released....
POW! ....as the plane instantly shoots forward through the air.......

Atl5p...your imagination is great...unfortunately you can't make the distinction from reality...
MikeMonty
QUOTE (AmazedByThis+Dec 11 2006, 07:18 PM)

Hey Mike and Bloy!
Here's my question for you.
Take a single engine Cessna, like a 172. Put it on the moving runway, and within one second of powering it up, have the runway go in the opposite direction 1 million miles per hour.  Do you think the plane will still take off?

Why use a real-world plane and a imaginary belt?
Why should I defend from a position of weakness that you impose?

Isn't it a bit dishonest (I don't mean that in a moral sense ) to insist on limiting the plane and not limiting the belt?

if you can give the belt the physical attributes required to run up to absurd speeds -(near unlimited power and material properties) then you must give the plane the same attributes.

This is why the argument goes round in circles - there is a discontinuity here that can only be resolved by taking the problem entirely into either real or imaginary worlds.
I tried previously to develop a model (not numerical) previously to support my real world argument - I even humoured ATL5P by including his red herrings.

In the imaginary world its an war of escalation between more power to plane / more power to conveyor that can't really be won on a physical level.

In the real world the case for plane takeoff is perhaps more in favour of the plane taking off, we are now into real engineering, and the factors favour the real and well demonstrated plane over the putative conveyor belt.

Can we try a bastardised version of Occam's Razor on the scenario?
Between two competing theories, all other things being equal, the simpler, more plausible is the better one.

Which is more plausible, the massive, high power conveyor, with inertia neglected, as it has been, against a proven technology like a cessna?

Mike
Atl5p
QUOTE (NoCleverName+Dec 11 2006, 03:17 PM)
Ya, the harrier does this, F-22 raptor, high-lift planes.

Just avoids the problem.

Speaking of avoiding the problem, ol' Atl5p is making a classic scientific move of asking the question in a different way on a new thread. Let's just everybody answer it.

The Harrier does it, sure.....not the Raptor (unless it starts out pointed upwards).

Oh, and don't forget the Marines version of the Joint Strike Fighter...VTOL.

Let's see...reviewing the OP....VTOL...VTOL....nope, don't see it anywhere.

Look, NoCleverAnything....why don't you do everyone a favor and stick to the 'simple' topics...feel no pressure to answer other threads that may discredit your responces in other threads.
NoCleverName
QUOTE (Atl5p+Dec 11 2006, 08:29 PM)
QUOTE (NoCleverName @ Dec 11 2006, 03:17 PM)
Ya, the harrier does this, F-22 raptor, high-lift planes.

Just avoids the problem.

Speaking of avoiding the problem, ol' Atl5p is making a classic scientific move of asking the question in a different way on a new thread. Let's just everybody answer it.

I believe my actual post was:

QUOTE
QUOTE (NoCleverName @ Dec 11 2006, 03:17 PM)
Ya, the harrier does this, F-22 raptor, high-lift planes.

Just avoids the problem.

Speaking of avoiding the problem, ol' Atl5p is making a classic troll move of forking the problem to a new thread. Let's just nobody answer it.

Was there some reason you needed to change my words and call it a direct quote?
Atl5p
QUOTE (MikeMonty+Dec 11 2006, 03:27 PM)
Why use a real-world plane and a imaginary belt?
Why should I defend from a position of weakness that you impose?

Isn't it a bit dishonest (I don't mean that in a moral sense ) to insist on limiting the plane and not limiting the belt?

if you can give the belt the physical attributes required to run up to absurd speeds -(near unlimited power and material properties) then you must give the plane the same attributes.

This is why the argument goes round in circles - there is a discontinuity here that can only be resolved by taking the problem entirely into either real or imaginary worlds.
I tried previously to develop a model (not numerical) previously to support my real world argument - I even humoured ATL5P by including his red herrings.

In the imaginary world its an war of escalation between more power to plane / more power to conveyor that can't really be won on a physical level.

In the real world the case for plane takeoff is perhaps more in favour of the plane taking off, we are now into real engineering, and the factors favour the real and well demonstrated plane over the putative conveyor belt.

Can we try a bastardised version of Occam's Razor on the scenario?
Between two competing theories, all other things being equal, the simpler, more plausible is the better one.

Which is more plausible, the massive, high power conveyor, with inertia neglected, as it has been, against a proven technology like a cessna?

Mike

Nice try (again) but I'm finding it very difficult to follow your latest argument....one that limits the treadbelt's power so that it could NEVER hold the plane at 0 IAS.
Weird.

In the OP, it clearly states that the treadbelt 'matches plane's speed exactly', and we know the plane's speed to be 'speed over the surface of the runway'. So the treadbelt MATCHES this speed. Just because we are finding that this is going to be a really fast speed, did you really think you could come in and say

'Sure the OP said the belt would match the plane's speed, but I'm sure it didn't mean THAT fast!'.

Ok, let's go with it....what is the speed limit of the treadbelt, 3cardMonty? And for how heavy a plane? With how much power? With what size tires?

So, you REALLY want the question to state 'Treadbelt matches plane's speed EXACTLY, unless it get's too fast, in which case the treadbelt will cease to match the plane's speed'.

Suggestion: Go start a new thread.
MikeMonty
QUOTE (NoCleverName+Dec 11 2006, 08:43 PM)
I believe my actual post was:

Was there some reason you needed to change my words and call it a direct quote?

Seems to be a bizarre new twist in his argument style - He's done much the same with some of my posts.
Bloy
QUOTE (Bloy @ Dec 11 2006, 08:42 PM)
Atl5p simply chose to interpret the original question from an unrealistic point of view.
Once he made the unrealistic "stab", he continues to defend his position regardless of how absurd his reasoning has to get.

Plain and simple(no pun intended), Atl5p remains outside the realm of reality.

by the way, Atl5p....what happens when the belt and plane reach the speed of light?

This is a condition present in YOUR scenario. It must be addressed!

Remember, Atl5p, this is scientific!! Hee hee....

Now, now, now, ATl5p, you aren't going to pull a punch and drift halfway back into a semi-real world, now are you?
egnorant
QUOTE (Atl5p+Dec 11 2006, 09:05 PM)

In the OP, it clearly states that the treadbelt 'matches plane's speed exactly', and we know the plane's speed to be 'speed over the surface of the runway'. So the treadbelt MATCHES this speed.

Just who is this WE that know the plane's speed to be speed over the surface of the moving runway??

Bruce
MikeMonty
QUOTE (Atl5p+Dec 11 2006, 09:05 PM)
Nice try (again)

"Nice try (again)

Thank you

but I'm finding it very difficult to follow your latest argument....one that limits the treadbelt's power so that it could NEVER hold the plane at 0 IAS.
Weird."

Nope, I'm limiting treadbelt acceleration to somewhere reasonable because you are limiting the plane to somewhere...... well........ where? .

In the OP, it clearly states that the treadbelt 'matches plane's speed exactly', and we know the plane's speed to be 'speed over the surface of the runway'. So the treadbelt MATCHES this speed. Just because we are finding that this is going to be a really fast speed, did you really think you could come in and say

'Sure the OP said the belt would match the plane's speed, but I'm sure it didn't mean THAT fast!'.

Actually I've said that your original definition was useless and asked you to fill in a couple of blanks to help me understand - you have steadfastly refused to do so - what does that say?

Ok, let's go with it....what is the speed limit of the treadbelt, 3cardMonty? And for how heavy a plane? With how much power? With what size tires?

I actually set out to do those figures at one point, then realised just how behaviourally abnormal that would be, so I stopped - if its important to you, YOU work it out. I'll allow you the output of a good-sized power station, so on you go. Oh no - I forgot - you can't!

So, you REALLY want the question to state 'Treadbelt matches plane's speed EXACTLY, unless it get's too fast, in which case the treadbelt will cease to match the plane's speed'.

Don't put words in my mouth - particularly your words - I'll tell you what I say, when I say it.
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