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#617725 - 01/01/07 02:36 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Rockaholic Offline
Member

Registered: 18/02/02
Posts: 1632
Loc: Reading, MA
Quote:
Originally posted by Hawk:
Just want to add that with this post, we tie Phat Chick Fridays in post count [Wave]
Unfortunately, no Hot chick pictures in this tread.....
_________________________
Jeffrey
I'm just trying to put my tires on the rocks of life.

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#617726 - 01/01/07 02:47 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Mobycat Offline
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Registered: 12/09/00
Posts: 8374
Loc: the hue of dungeons and the sc...
Just to make it relevant to both (and a beer thread, if there was one this long)...

_________________________
"Nature has constituted utility to man the standard and test of virtue. Men living in different countries, under different circumstances, different habits and regimens, may have different utilities; the same act, therefore, may be useful and consequently virtuous in one country which is injurious and vicious in another differently circumstanced" - Thomas Jefferson, moral relativist

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#617727 - 01/01/07 03:46 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


The plane takes off in approximately the same distance necessary on a conveyor belt as it does on a regular runway.

Since Blue-Sky is mentioning his 20 years "aviation" experience, I guess I'll throw mine into the hat, even though it too has no bearing on the problem... I'm an airport designer. Civil Engineer. I design Runways, Taxiways, Aprons, and all things associated except the electrical & navigational equipment. I've been doing this for 6 years, now.

I assure you, the friction of the wheel bearings does not matter to the plane taking off. How's that? Because different surfaces have different coefficients of friction already. Asphalt runways have different coeff. than concrete. Significantly different on paper; absolutely no difference in the real world. Why's that? Because both numbers are so small in relationship to the take-off thrust of any aircraft that it doesn't matter.

READ BELOW COMPLETELY FOR AS SIMPLE AN EXPLANATION AS YOU CAN GET ON WHY THE AIRPLANE WILL TAKE OFF

An aircraft's engine PUSHES (jet) / PULLS (prop) the aircraft along the ground. This results in a horizontal force on the axles of the aircarft because they are fixed rigidly to the aircraft. The by-product of this force is it causes ROTATION of the tires around the axles. The tires do nothing more than rotate around the axle; they do not cause any horizontal movement.

If a conveyor belt were under the tires, it too would cause rotation of the tires around the axles. But, it can not cause any movement and/or restriction of movement of the axles, as the tires do nothing but free-spin around them. Again, the conveyor belt spins the tires, but does not exert any horizontal force on the axle. You can test this "theory" by jacking up your truck (get a whole axle up in the air), and spinning a free-wheeled tire from below. The tire will spin, but the truck will NOT move. This is not because you aren't spinning the tire fast enough; spin it as fast as you want, and the truck still will not move. The truck can't move, because all the force you apply goes into spinning the tire; none of it is a horizontal force on the axle.

Summing the forces in the horizontal direction gives you a positive force from the engines, and 0 negative force, as the conveyor belt can not move the axles of the plane regardless of how fast it spins.

From Newton, Force = Mass x Acceleration. So divide the sum of the Forces (the engine force only as shown in the above paragraph) and divide by the Mass of the plane. What you get is the Acceleration of the aircraft. The friction is negligable, as it is an extremely small number compared to the Force.

The net result is the aircraft accelerates down the runway, and eventually obtains flight once there's enough lift provided by the air passing over the wings.

END EXPLANATION

And, it will reach its takeoff speed at the same distance down the runway as it would without the conveyor belt. The additional friction of the tires as they spin twice as fast is not enough to make a significant difference. Dynamic friction levels off at a certain point, and for all practical purposes remains a constant level whether the tire spins at 150 mph or 300 mph.

Editorial Comments...:
While this is a physics, it's also a Statics & Dynamics problem. A problem like this would be taught in a 200 level Engineering Dynamics course, and any Engineer that can't answer it with only a fleeting glance ought to take some continuing education classes in a hurry...

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#617728 - 01/01/07 04:05 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Mobycat Offline
Member
*****

Registered: 12/09/00
Posts: 8374
Loc: the hue of dungeons and the sc...
Quote:
Originally posted by porsche996:
The plane takes off in approximately the same distance necessary on a conveyor belt as it does on a regular runway.

Since Blue-Sky is mentioning his 20 years "aviation" experience, I guess I'll throw mine into the hat, even though it too has no bearing on the problem... I'm an airport designer. Civil Engineer. I design Runways, Taxiways, Aprons, and all things associated except the electrical & navigational equipment. I've been doing this for 6 years, now.
Interestingly enough, my brother is a civil engineer (with about the 20 years experience).

His take was that there would be no wind over the wings. BUT...he also made it a point to say it's a trick question.

Edit to add - if the plane is going 20 mph, does the conveyor think it's going 20mph to the ground or to itself?

If the conveyor thinks it's to itself, shouldn't it be impossible for the conveyor belt to match it? That is, if the conveyor think's the plane is going 20 mph to the conveyor belt, the conveyor belt goes to 20mph...but then the plane is going 40 mph to the belt - and so on and so on?

Which brings back the question - what's the speed in relation to?

If it's to the ground away from the plane - then the plane should take off. If it's to the ground underneath - the conveyor - it's an impossible scenario.
_________________________
"Nature has constituted utility to man the standard and test of virtue. Men living in different countries, under different circumstances, different habits and regimens, may have different utilities; the same act, therefore, may be useful and consequently virtuous in one country which is injurious and vicious in another differently circumstanced" - Thomas Jefferson, moral relativist

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#617729 - 01/01/07 04:12 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by Mobycat:
Interestingly enough, my brother is a civil engineer (with about the 20 years experience).

His take was that there would be no wind over the wings. BUT...he also made it a point to say it's a trick question.

Edit to add - if the plane is going 20 mph, does the conveyor think it's going 20mph to the ground or to itself?

If the conveyor thinks it's to itself, shouldn't it be impossible for the conveyor belt to match it? That is, if the conveyor think's the plane is going 20 mph to the conveyor belt, the conveyor belt goes to 20mph...but then the plane is going 40 mph to the belt - and so on and so on?

Which brings back the question - what's the speed in relation to?

If it's to the ground away from the plane - then the plane should take off. If it's to the ground underneath - the conveyor - it's an impossible scenario.
Speed isn't revolutions per second, which is what any measurement of the tires would give you. That's "angular speed", and not "speed". In a car, angular speed is translated into speed by the speedo, gears, and in newer ones, electronics. But the angular speed of the tires and the speed of the vehicle are never coinciding.

Moby, run my explanation by your brother and see what he has to say. Don't paraphrase; copy that last post directly and ask him about it. I'm betting a little light-bulb will go off over his head (maybe even a good palm-smacking of the forehead if he's that kinda' person) and he'll tell you the plane takes off...

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#617730 - 01/01/07 04:58 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by porsche996:

I'm an airport designer. Civil Engineer. I design Runways, Taxiways, Aprons, and all things associated except the electrical & navigational equipment. I've been doing this for 6 years, now.
What does potassium acetate mean to you on a concrete runway?

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#617731 - 01/01/07 05:24 PM Re: Know that if you do not post in this thread today the human race may cease to exist
XPLORx4 Offline
Member

Registered: 23/03/01
Posts: 1906
Loc: San Jose, CA
An aircraft's ability to leave a conveyor-belt runway is influenced PREDOMINANTLY by the speed rating of its tires.

I briefly searched google, and found that a common speed rating of many aircraft tires is 160knots . There are some tires with speed ratings as high as 225knots.

Most people in this discussion believe that the aircraft will take off on a conveyor belt. A few still hold onto the fact that the plane never moves relative to its surroundings, which has been disproved many times.

The plane DOES move towards the end of the runway, which moves backwards at the same rate, making only the tires spin faster (but the plane still moves forwards). Wheel bearing friction is negligible, provided proper bearing maintenance. However, if the tire speed exceeds 160knots, which means the plane's groundspeed/airspeed can only be 80knots, the tire is at risk of failure while it's on the conveyor belt. Most planes require airspeeds of approx 80-90knots to acquire lift. On the scenario's conveyor belt, the tires would have to spin at an effective speed at 180knots, which is a little faster than the speed rating of the tire.

As long as the tire can hold together before the plane takes off, the plane will fly away. But if the tire fails before then, the plane is probably going to lose control near the end of the runway and probably crash.
_________________________
4x4 in uppercase is $X$!!!
1997 R50: VG33E/RE4R01A/TX10/3.7/R200A/ARB/4.636/H233B/ARB/4.636/321150R15

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#617732 - 01/01/07 05:36 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by Eric P.:
Quote:
Originally posted by porsche996:
[b]
I'm an airport designer. Civil Engineer. I design Runways, Taxiways, Aprons, and all things associated except the electrical & navigational equipment. I've been doing this for 6 years, now.
What does potassium acetate mean to you on a concrete runway?[/b]
Means nothing to me. My airports don't use potassium acetate in their deicing ops. I'm in Louisville for cripes sake... We don't need extreme cold temperature deicing.

Only airport I've done work for that has extensive deicing operations was Denver, and I only worked on the design of a Frontier apron that never got built, so far as I know. That was almost 2 years ago.

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#617733 - 01/01/07 05:48 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by XPLORx4:
An aircraft's ability to leave a conveyor-belt runway is influenced PREDOMINANTLY by the speed rating of its tires.

I briefly searched google, and found that a common speed rating of many aircraft tires is 160mph . There are some tires with speed ratings as high as 225mph.

Most people in this discussion believe that the aircraft will take off on a conveyor belt. A few still hold onto the fact that the plane never moves relative to its surroundings, which has been disproved many times.

The plane DOES move towards the end of the runway, which moves backwards at the same rate, making only the tires spin faster (but the plane still moves forwards). Wheel bearing friction is negligible, provided proper bearing maintenance. However, if the tire speed exceeds 160mph, which means the plane's airspeed can only be 80mph, the tire is at risk of failure while it's on the conveyor belt. Most planes require airspeeds over 100mph to acquire lift. On the scenario's conveyor belt, the tires would have to spin at an effective speed at over 200mph, more than 25% faster than the speed rating of the tire.

As long as the tire can hold together before the plane takes off, the plane will fly away. But if the tire fails before then, the plane is probably going to lose control near the end of the runway and probably crash.
Wow. You're reading way too much into the problem...

If it makes you feel any better, nobody ever said the airplane had tires to begin with. The original problem statement never said either way. For all we know, the plane is sitting on skids, and the conveyor belt is covered in butter to reduce friction...

But...
Goodyear Airplane tires

According to Good Year, they have tires rated up to 230 MPH.

So if it's a small plane w/ takeoff of 60 knots (indicated air speed) such as the Cessna 172R, then not only does it take off, but the wheels don't even come close to their max speed...

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#617734 - 01/01/07 05:57 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Wow this is some intense shit... Seriously thou.. Can't we all just get along and just say who gives a rip if the plane takes off.. Who the hell puts a plane on treadmill anyways??

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#617735 - 01/01/07 06:29 PM Re: Know that if you do not post in this thread today the human race may cease to exist
MidnightX Offline
Member
*****

Registered: 08/03/01
Posts: 3745
Loc: Jacksonville, Florida
smile

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#617736 - 01/01/07 06:32 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Yes-how about Britney's twat.

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#617737 - 01/01/07 06:38 PM Re: Know that if you do not post in this thread today the human race may cease to exist
spalind Offline
Member

Registered: 30/01/03
Posts: 3238
Loc: Windham, NH
Quote:
Originally posted by Joe Kanter:
Yes-how about Britney's twat.
I thought she was referring to nudie pictures of herself....

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#617738 - 01/01/07 06:59 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Ok, in just 5 days this thread has already exceeded the page count of the Phat Chicks thread.
That's really really sad. I'm disappointed in all of you. eek

Except Lizz. Never shoot the messenger. Or the person who helps with your Clearcoat Quest.

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#617739 - 01/01/07 07:40 PM Re: Know that if you do not post in this thread today the human race may cease to exist
GrayHam Offline
Member

Registered: 17/04/01
Posts: 8849
Lizz,

Feel free to PM more nude pics of yourself to me.

I lost the last set.

Thanks, doll.

-Graham
_________________________
Does anybody remember laughter?

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#617740 - 01/01/07 07:43 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


If you could CC me on those pics I would really appreciate it Liz, darling....

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#617741 - 01/01/07 07:48 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Lightning Offline
Member

Registered: 07/03/01
Posts: 1004
Loc: High Point, NC
I've avoided this thread for 5 days now... and then you lure me here with nudie shots and it's just a tease! Drat! Hmm, is it really worth my while I'm here to read 45 pages to see what this thread is all about and to get caught up?
_________________________
'00 4x4 V6 XE

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#617742 - 01/01/07 08:17 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by Lightning:
I've avoided this thread for 5 days now... and then you lure me here with nudie shots and it's just a tease! Drat! Hmm, is it really worth my while I'm here to read 45 pages to see what this thread is all about and to get caught up?
WTF? More pages than the Phat chicks thread and no pics? mad

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#617743 - 01/01/07 08:44 PM Re: Know that if you do not post in this thread today the human race may cease to exist
socalpunx Offline
Member

Registered: 24/08/01
Posts: 6327
Loc: The land of losers and liberal...
This might be more your speed:

Words and Pictures laugh
_________________________
If we do not succeed, then we run the risk of failure. - Vice President James Danforth "Dan" Quayle

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#617744 - 01/01/07 10:06 PM Re: Know that if you do not post in this thread today the human race may cease to exist
NY Madman Offline
Member
*

Registered: 09/05/02
Posts: 5232
Loc: Florida
This thread has grown a lot in the last couple of days.

I'll give my assessment so far....

The people who say that the plane will fly have offered some good arguments but every single one is completely flawed.

Some arguments are more flawed than others, but there are flaws in all of them.

Some are even claiming now that the plane is moving down the conveyor just like it would on a regular runway. If that were true, there would be no question or hypothetical scenario.

Many people claim their arguments are based on physics. That may be so, but they certainly are not based on aerodynamics.

Some have even posted a comment from a physics professor. It makes no difference what he says because there are people arguing all aspects of this scenario on the internet who are also college professors and scientists. Many of those scientists say the plane will not fly.

I've noticed many people have gotten very far away from the original scenario. Most of those are in the camp that the plane will fly. Many are completely ignoring the original scenario.

It's both surprising and shocking at the amount of extraneous stuff that has been brought into the debate.

I think people need to focus purely on the original scenario and aerodynamic principles.

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#617745 - 01/01/07 10:24 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Xterrian Offline
Member
*

Registered: 08/12/00
Posts: 2014
Loc: Fort Lewis, WA
Ny Madman, I specifically asked you not to reply to this thread without PM'ing me and yet here is a post from you continuing to debate this scenario without a PM in my box. I was trying to protect you, but you seem to be more interested in proving to me that I was wrong all this time and that there is no intelligence there, just ego. I'm very disapointed and will never believe any argument you post from this point forward on any topic as it is obvious that you are interested in being right no matter how wrong you are and will gladly wear a blindfold and earplugs if that is what it takes to believe you are right.

My statement at the 45 page mark is that anyone that still does not understand that the plane will fly is a complete fucking idiot. It can not be explained any simpler or in a more complex manner than it has been so far in this thread. My 12 year old son understood it without any explanation at all.

Please post a reference to any proffesor that states that the plane will not fly so I wiil know where not to send my kids to school.
_________________________
"The trouble ain't that there is too many fools, but that the lightning ain't distributed right."
Mark Twain

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#617746 - 01/01/07 10:34 PM Re: Know that if you do not post in this thread today the human race may cease to exist
NY Madman Offline
Member
*

Registered: 09/05/02
Posts: 5232
Loc: Florida
Quote:
Originally posted by Xterrian:

Ny Madman, I specifically asked you not to reply to this thread without PM'ing me and yet here is a post from you continuing to debate this scenario without a PM in my box.
And who are you? My boss.

Quote:
I was trying to protect you, but you seem to be more interested in proving to me that I was wrong all this time and that there is no intelligence there, just ego.
You were wrong. You include "assumptions" in your argument.

And since when did this discussion become about ego?

Quote:
I'm very disapointed and will never believe any argument you post from this point forward on any topic as it is obvious that you are interested in being right no matter how wrong you are and will gladly wear a blindfold and earplugs if that is what it takes to believe you are right.
So now I am wrong for pointing out flaws in other people's arguments. [Freak]

You need to remove emotion from your arguments.

Quote:
My statement at the 45 page mark is that anyone that still does not understand that the plane will fly is a complete fucking idiot. It can not be explained any simpler or in a more complex manner than it has been so far in this thread. My 12 year old son understood it without any explanation at all.


You are a fucking idiot for making what was and should be a rational debate into your own personal forum and for taking things personally.

Quote:
Please post a reference to any proffesor that states that the plane will not fly so I wiil know where not to send my kids to school.
A couple of people have already provided links to people much smarter than you who say you are wrong.

Rinky also provided a link to a thread that is 500 pages long. There are engineers and scientists in that thread. Good Luck with your reading.

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#617747 - 01/01/07 10:35 PM Re: Know that if you do not post in this thread today the human race may cease to exist
socalpunx Offline
Member

Registered: 24/08/01
Posts: 6327
Loc: The land of losers and liberal...
Quote:
Originally posted by Xterrian:
Ny Madman, I specifically asked you not to reply to this thread without PM'ing me and yet here is a post from you continuing to debate this scenario without a PM in my box. I was trying to protect you, but you seem to be more interested in proving to me that I was wrong all this time and that there is no intelligence there, just ego. I'm very disapointed and will never believe any argument you post from this point forward on any topic as it is obvious that you are interested in being right no matter how wrong you are and will gladly wear a blindfold and earplugs if that is what it takes to believe you are right.

My statement at the 45 page mark is that anyone that still does not understand that the plane will fly is a complete fucking idiot. It can not be explained any simpler or in a more complex manner than it has been so far in this thread. My 12 year old son understood it without any explanation at all.

Please post a reference to any proffesor that states that the plane will not fly so I wiil know where not to send my kids to school.
To be honest, there is something very juvinile and sophmoric about the whole "I'm right and anyone who doesn't agree with me is a fucking idiot" mentality.

A) Madman is under no obligation to PM you merely because you deem it to be necessary.

B)Your resume based on what you stated is that you are/were an airplane mechanic which while the determination can be made that you understand the mechanics of the systems involved in airplanes, it does not make you the finite expert on the physics, engineering and other issues being debated in this question.

C)A lot of other people that are a hell of a lot smarter than you have discussed and debated both sides of this question for a lot longer and in terms that you likely will never comprehend. So instead of claiming to be the be all and end all of the argument just enjoy the warm fuzzy feeling that you obviously think you know the answer.

So please. If the guy wants to argue with whoever wants to argue with him by all means, either argue away at your leisure or feel content that you stated your case, believe you are correct, and move on to something more worthy of your expertise.
_________________________
If we do not succeed, then we run the risk of failure. - Vice President James Danforth "Dan" Quayle

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#617748 - 01/01/07 11:17 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Still waiting for that twat shot of Britney.

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#617749 - 01/01/07 11:29 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Xterrian Offline
Member
*

Registered: 08/12/00
Posts: 2014
Loc: Fort Lewis, WA
Thanks for commenting on my intelligence, but if it's a comment coming from one of the CF crowd, please don't take offense if it doesn't bother me.

I've always felt NYMM got a bad wrap here and felt sorry for him and was a bit aggravated that he continues to prove himself a fool despite my desire to help him out.

I can guarantee that no one smarter than me believes the plane won't fly.

We make the ALR yet? laugh
_________________________
"The trouble ain't that there is too many fools, but that the lightning ain't distributed right."
Mark Twain

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