shrockworks xterraparts
XOC Decal
Newest Members
Glim, ChossWrangler, Patman, ChargedX, Randy Howerton
10084 Registered Users
Recent Posts
Time To Replace Exhaust
by all2surreal
06/11/17 01:57 PM
2000 Xterra accessories for sale
by csebes
22/10/17 05:12 PM
Shout Box

Who's Online
0 registered (), 109 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Page 23 of 43 < 1 2 ... 21 22 23 24 25 ... 42 43 >
Topic Options
Rate This Topic
#617625 - 31/12/06 08:21 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Wow. Up to 37 pages, and there's still a handful of morons that think the wheels on an airplane control the airplane's motion...

Guys, it's pretty simple. The original statement says the belt goes the same speed as the plane, but in an opposite direction.

If the plane has no forward motion (speed), then the belt does not move.

If the plane goes forward at 10 mph, then the belt goes in reverse at 10 mph.

If the plane goes forward at 150 mph, then the belt goes in reverse at 150 mph.

But what does that mean to an outside observer, for Madman's benefit? It means that the person, standing still, sees a plane moving forward at 10mph, then accelerating up to 150 mph, and then taking off.

Nowhere in the original problem statement does it say the belt matches the speed of the tires. The belt matches the speed of the AIRPLANE. The speed of the tires are relative to the forward motion of the plane, and the reverse motion of the belt.

In this scenario, the plane's movement forward makes the tires rotate forward. The conveyor belt moving backwards makes the tires rotate forward as well (think of it like two gears in contact with each other; turn one, and the other moves in the opposite direction). The actual rotational speed of the tires is the sum of both inputs, airplane speed plus conveyor speed. So if the plane is moving at 10 mph, and the conveyor belt is moving at 10mph the opposite direction, the tires are rotating at 20 mph.

The thing is, there are two completely independent forces acting on the tires. There is the force from the engines of the plane, pushing air and not directly in contact w/ the tires. Then there's the force of the conveyor belt acting directly on the tires. The tires move based on the two inputs.

The problem that everyone that thinks the plane won't take off is the external power source of the engines. The force of the engines acts on the body of the plane. The tires only spin by the plane if the plane is moving forward and the tires are in contact with the ground. The force of the belt acts directly on the tires, causing them to do nothing more than spin in the forward direction. But again, the tires spinning in the forward direction do not cause the body of the aircraft to move, as they are only free spinning along the axle shaft, with no mechanical linkage to force the aircraft forward.

Guys, the plane has not only taken off on the original page, but it already landed at it's destination, and all the passengers have been sitting at home reading this thread, knowing PERSONALLY that the "won't take off" group are out of their minds...

Top
#617626 - 31/12/06 08:31 AM Re: Know that if you do not post in this thread today the human race may cease to exist
BlueSky Offline
Member

Registered: 17/08/00
Posts: 2286
Loc: Georgia
I disagree, but respectfully. I know the wheels don't control the plane's motion, but I also know they are the means by which engine power is converted to forward motion over the ground when the aircraft isn't flying.

Calling people morons because they don't share your point of view - which very well may be wrong, Einstein - makes you a gold-plated asshat. IMHO of course. [Finger]

Top
#617627 - 31/12/06 08:41 AM 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 BlueSky:
I disagree, but respectfully. I know the wheels don't control the plane's motion, but I also know they are the means by which engine power is converted to forward motion over the ground when the aircraft isn't flying.

Calling people morons because they don't share your point of view - which very well may be wrong, Einstein - makes you a gold-plated asshat. IMHO of course. [Finger]
Yes, I am an asshat. I have no problems admitting that.

But if you think the force of motion of an airplane is magically created by the tires when a plane is on the ground, but created by the engines when it's in the air, then frankly, yes, you are a moron.

Forward motion of the plane is caused by the engines pushing the plane forward, whether it's in the air, on the ground, on the water, or wherever. Never, ever, is forward motion either caused or restricted by the tires on the ground.

I'm no einstein, but I'm evidently smart enough to know where the force for the motion comes from for a plane, and that it doesn't magically shift from one thing to another based on the plane's position... [Finger]

Blue, the tires DIRECT the motion of the plane on the ground; the same as the ailerons and rudder DIRECT the motion of the plane in the air. NONE of those things either cause or prevent motion that is originated by the force applied by the ENGINES.

Top
#617628 - 31/12/06 09:08 AM 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 BlueSky:
I disagree, but respectfully. I know the wheels don't control the plane's motion, but I also know they are the means by which engine power is converted to forward motion over the ground when the aircraft isn't flying.
And the wheels don't care if the ground is moving under the plane, if the plane is moving over the ground, or both at the same time...

The wheel rotational speed does not have to equal the plane speed.
Quote:
Calling people morons because they don't share your point of view - which very well may be wrong
See my last post -cars/plane moving onto the moving conveyor- to understand why the plane moves and thus takes off...
_________________________
Jeffrey
I'm just trying to put my tires on the rocks of life.

Top
#617629 - 31/12/06 09:18 AM Re: Know that if you do not post in this thread today the human race may cease to exist
BlueSky Offline
Member

Registered: 17/08/00
Posts: 2286
Loc: Georgia
Quote:
Originally posted by porsche996:
Quote:
Originally posted by BlueSky:
[b]I disagree, but respectfully. I know the wheels don't control the plane's motion, but I also know they are the means by which engine power is converted to forward motion over the ground when the aircraft isn't flying.

Calling people morons because they don't share your point of view - which very well may be wrong, Einstein - makes you a gold-plated asshat. IMHO of course. [Finger]
Yes, I am an asshat. I have no problems admitting that.

But if you think the force of motion of an airplane is magically created by the tires when a plane is on the ground, but created by the engines when it's in the air, then frankly, yes, you are a moron.

Forward motion of the plane is caused by the engines pushing the plane forward, whether it's in the air, on the ground, on the water, or wherever. Never, ever, is forward motion either caused or restricted by the tires on the ground.

I'm no einstein, but I'm evidently smart enough to know where the force for the motion comes from for a plane, and that it doesn't magically shift from one thing to another based on the plane's position... [Finger]

Blue, the tires DIRECT the motion of the plane on the ground; the same as the ailerons and rudder DIRECT the motion of the plane in the air. NONE of those things either cause or prevent motion that is originated by the force applied by the ENGINES.[/b]
I didn't say the tires CREATED the plane's motion, I said they are the instrument through which forward motion occurs. Don't believe that? Retract the gear and see how far you go.

Apply thrust, what happens? The tires roll and the plane moves over the ground. The thrust provides the power but the tires rolling results in the plane moving.

Now apply the brakes. The tires stop and so does the plane (assuming there's not enough thrust to overcome the braking action). The tires didn't stop the plane, the brakes did, but the tires were the catalyst through which the braking action caused a RESULT - the plane stopping.

We'll apparently agree to disagree. I'm a moron and you're an asshat. Do those cancel each other out? laugh

P.S. Did you read my post 2nd from the top on this page?

Top
#617630 - 31/12/06 09:25 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Rockaholic, I'm glad you got it right. It's easy to get hung up on something, in fact, that's what the question's designed for.

For Bluesky, Madman, Mobycat and any other CF-rs, answer my earlier question please.

The aircraft is already airborne and on approach to the conveyor/runway for a touch-and-go. The runway is spinning at exactly the same speed in the opposite direction, just like when it took off. laugh Now, when the aircraft touches down (no brakes, remember, doing a touch-and-go) will it immediatly come to a complete stop and be unable to take off again (do the "go" part)?

Top
#617631 - 31/12/06 09:30 AM 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 MattyX:
Rockaholic, I'm glad you got it right. It's easy to get hung up on something, in fact, that's what the question's designed for.

For Bluesky, Madman, Mobycat and any other CF-rs, answer my earlier question please.

The aircraft is already airborne and on approach to the conveyor/runway for a touch-and-go. The runway is spinning at exactly the same speed in the opposite direction, just like when it took off. laugh Now, when the aircraft touches down (no brakes, remember, doing a touch-and-go) will it immediatly come to a complete stop and be unable to take off again (do the "go" part)?
It *ALREADY HAS* foward momentum in the air.

The conveyor belt scenario - it does not start with forward momentum. It cannot attain it, because the conveyor keeps it from gaining it.
_________________________
"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

Top
#617632 - 31/12/06 09:34 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Sure, but if what you're saying is correct, once the wheels are on the conveyor (full weight, just like every touch-and-go), the forces applied to the tires should stop the aircraft flat.

Top
#617633 - 31/12/06 09:36 AM 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 BlueSky:
For the plane to move forward, 2πR MUST be greater than the distance the treadmill moves backward, but the scenario says the belt matches the plane's speed, so the result can't be greater than zero.

On a runway of course, there's no counter-motion backwards so 2πR is always greater than zero, resulting in forward motion.
Now you have a serious problem...See this scenario I posted and you've been ignoring...
Quote:
The conveyor is set up to match the airplanes speed, so if the airplane is moving at 10 mph, so is the conveyor in the exact opposite direction.

The originally scenario does not say that the planes causes the conveyor to move, but that the conveyor is moved by some other control to match speed of the plane.

So if the plane is off of the conveyor on hard ground moving towards the conveyor at 10mph, then the conveyor is still going to move at 10mph in the opposite direction...Now, an Airplane has front wheels and rear wheels, so what happens when the airplane moves onto the conveyor?
Now revisiting what you said - the wheels of the plane on the conveyor have a counter motion from the conveyor, so the result is always zero (no motion) whearea the wheels of the plane on a runway have no counter motion, and thus always have a result of greater than zero (forward motion)

Now the problem is that the length of the plane and the distance bewteen the wheels remains a constant, and based on what you posted: The the front wheels of the plane on the treadmill have a counter motion and so the result can't be greater than zero, so there is no forward motion; yet the rear wheels (on the solid ground) have no counter motion, so those wheels are moving forward...

How can the rear wheels be moving forward if the front wheels are not moving forward when the distance between the wheels remains constant? That is physically impossible!
_________________________
Jeffrey
I'm just trying to put my tires on the rocks of life.

Top
#617634 - 31/12/06 10:01 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Obviously people who have never taken a physics class find this tuff hard to grasp.

Please prove this answer wrong:
(since you claim it is incorrect)

Quote:
Originally posted by JeffW:
Relavent information:

A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).

Will the plane be able to take off?

Let's agree on what assumptions are sensible then. All of the assumptions below apply to virtually all aircraft.

Plane is powered by engines that push air (props or jets)
Plane's speed is measured by a windspeed meter as well as GPS
Plane's wheels spin freely
Wheel friction is negligible when compared to thrust
Newtonian physics apply



Coefficient of dynamic friction:

Force of friction:

F(f) = -uN

(negative because it opposes motion)

u = coefficient of static friction

N = weight of plane

Notice velocity is not included!

That means that the velocity of the conveyor belt is irrelevant for all practical purposes.

F(t) is force of thrust

a = (F(t)+F(f))/m

You won't find a scenario where |F(f)| is greater than |F(t)|. Therefore, in ALL cases the plane moves with respect to the atmosphere, thus achieving lift.

Possible scenario:

t = 0 :

Plane 0 mph
Conveyor 0 mph
Wheels 0 mph

t = 15 :

Plane 60 mph
Conveyor 60 mph
Wheels spin @ 120 mph

t = 55:

Plane 160 mph
Conveyor 160 mph
Wheels spin @ 320 mph

....

The plane takes off.

Either learn why it is correct or refute it....

..scientifically.

Top
#617635 - 31/12/06 10:19 AM 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 Mobycat:
It *ALREADY HAS* foward momentum in the air.

The conveyor belt scenario - it does not start with forward momentum. It cannot attain it, because the conveyor keeps it from gaining it.
You agree then that the plane continues to move over the conveyor belt....
So what you are saying is the conveyor belt stops the object on the belt from gaining momentum, yet it doesn't stop and object in motion before being on the conveyor from losing it's momentum once it is on the conveyor.

So then why doesn't the front wheel drive car pull the rear wheels up onto the conveyor? It also has it's momentum throug the air before getting onto the conveyor belt.
Is it because the front wheels would have to be moving forward when they are experiencing a counter motion, which would have to be impossible in order for the plane to remain in the exact same spot on the conveyor....and then the rear wheel would have to be moving forward without any motion from the ground(because the ground doesn't move and the engine doesn't provide any motion to the free spinng rear wheels) and thus would have to move without a counter motion of the ground...

So how is this conveyor belt magically stopping the cars but not stopping the plane?

You've agreed the pane keeps moving after all, so why not the cars? (Beause their method of forward propulsion is different)

Or how is this plane magically moving it's rear wheels, while not moving it's front wheels, while at the same time the wheels remain a constant distance apart?
_________________________
Jeffrey
I'm just trying to put my tires on the rocks of life.

Top
#617636 - 31/12/06 10:56 AM 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
I think that the "can't fly" folks have this in common: short attention span. If any post is longer than about 5 lines, they stop reading and immediately post their reply to the first 5 lines of the previous post.

All the scenarios countering their arguments are summarily ignored because the CF'ers never read them.

As a result, this thread is never gonna take off.
_________________________
4x4 in uppercase is $X$!!!
1997 R50: VG33E/RE4R01A/TX10/3.7/R200A/ARB/4.636/H233B/ARB/4.636/321150R15

Top
#617637 - 31/12/06 10:57 AM Re: Know that if you do not post in this thread today the human race may cease to exist
BlueSky Offline
Member

Registered: 17/08/00
Posts: 2286
Loc: Georgia
Quote:
Originally posted by XPLORx4:
I think that the "can't fly" folks have this in common: short attention span. If any post is longer than about 5 lines, they stop reading and immediately post their reply to the first 5 lines of the previous post.

All the scenarios countering their arguments are summarily ignored because the CF'ers never read them.

As a result, this thread is never gonna take off.
Nice job editing your post to take out the part indicating that you hadn't read all of my post. You're funny...not to mention full of s***.

Top
#617638 - 31/12/06 11:02 AM Re: Know that if you do not post in this thread today the human race may cease to exist
BlueSky Offline
Member

Registered: 17/08/00
Posts: 2286
Loc: Georgia
Quote:
Originally posted by JeffW:
Obviously people who have never taken a physics class find this tuff hard to grasp.

Please prove this answer wrong:
(since you claim it is incorrect)

Quote:
Originally posted by JeffW:
[b]Relavent information:

A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).

Will the plane be able to take off?

Let's agree on what assumptions are sensible then. All of the assumptions below apply to virtually all aircraft.

Plane is powered by engines that push air (props or jets)
Plane's speed is measured by a windspeed meter as well as GPS
Plane's wheels spin freely
Wheel friction is negligible when compared to thrust
Newtonian physics apply



Coefficient of dynamic friction:

Force of friction:

F(f) = -uN

(negative because it opposes motion)

u = coefficient of static friction

N = weight of plane

Notice velocity is not included!

That means that the velocity of the conveyor belt is irrelevant for all practical purposes.

F(t) is force of thrust

a = (F(t)+F(f))/m

You won't find a scenario where |F(f)| is greater than |F(t)|. Therefore, in ALL cases the plane moves with respect to the atmosphere, thus achieving lift.

Possible scenario:

t = 0 :

Plane 0 mph
Conveyor 0 mph
Wheels 0 mph

t = 15 :

Plane 60 mph
Conveyor 60 mph
Wheels spin @ 120 mph

t = 55:

Plane 160 mph
Conveyor 160 mph
Wheels spin @ 320 mph

....

The plane takes off.

Either learn why it is correct or refute it....

..scientifically.
[/b]
While I work on refuting yours, can you refute my distance traveled equation? Or did you bother to read the post?

Top
#617639 - 31/12/06 11:02 AM 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
Blue, I did read all of your post (2nd from the top on p37), and it's flawed.

Without responding to all of your 2piR references, the major flaw is you (and other CF'ers) fail to see that motion through air and motion over ground are two different things. Do you understand that you can have motion over ground without motion through air (i.e. tailwind)? Do you understand that you can have motion through air without motion over ground (headwind)?

Answer those two questions for me.
_________________________
4x4 in uppercase is $X$!!!
1997 R50: VG33E/RE4R01A/TX10/3.7/R200A/ARB/4.636/H233B/ARB/4.636/321150R15

Top
#617640 - 31/12/06 11:10 AM 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
Better yet, read --> this <-- .
_________________________
4x4 in uppercase is $X$!!!
1997 R50: VG33E/RE4R01A/TX10/3.7/R200A/ARB/4.636/H233B/ARB/4.636/321150R15

Top
#617641 - 31/12/06 11:16 AM Re: Know that if you do not post in this thread today the human race may cease to exist
BlueSky Offline
Member

Registered: 17/08/00
Posts: 2286
Loc: Georgia
Quote:
Originally posted by XPLORx4:
Blue, I did read all of your post (2nd from the top on p37), and it's flawed.

Without responding to all of your 2piR references, the major flaw is you (and other CF'ers) fail to see that motion through air and motion over ground are two different things. Do you understand that you can have motion over ground without motion through air (i.e. tailwind)? Do you understand that you can have motion through air without motion over ground (headwind)?

Answer those two questions for me.
Uh, yeah, I understand those things. Like why it can take 15.5 hours to fly LAX-HKG and only 12 hours to fly the same route back? Winds.

Do YOU understand that those two things are irrelevant if the plane is stationary on the ground and has not achieved flight?

Top
#617642 - 31/12/06 11:36 AM 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
Quote:
Originally posted by BlueSky:
Do YOU understand that those two things are irrelevant if the plane is stationary on the ground and has not achieved flight?
No, I do not, because airspeed and groundspeed are relevant at all times. A moving car has both airspeed and groundspeed, do you agree? (If you don't think a car has airspeed, stick your hand out the window. But cars don't care about airspeed, since it's the motion over the ground that we care about). Additionally, a STATIONARY car can have airspeed without groundspeed on a windy day. Again, stick your hand out the window. Feel the air moving past the car? That's airspeed. Notice the ground isn't moving, but the air is!

The same things apply to aircraft, whether in the air or on the ground. Do you agree?
_________________________
4x4 in uppercase is $X$!!!
1997 R50: VG33E/RE4R01A/TX10/3.7/R200A/ARB/4.636/H233B/ARB/4.636/321150R15

Top
#617643 - 31/12/06 11:38 AM Re: Know that if you do not post in this thread today the human race may cease to exist
BlueSky Offline
Member

Registered: 17/08/00
Posts: 2286
Loc: Georgia
Quote:
Originally posted by XPLORx4:
Quote:
Originally posted by BlueSky:
[b]Do YOU understand that those two things are irrelevant if the plane is stationary on the ground and has not achieved flight?
No, I do not, because airspeed and groundspeed are relevant at all times. A moving car has both airspeed and groundspeed, do you agree? (If you don't think a car has airspeed, stick your hand out the window). Additionally, a STATIONARY car can have airspeed without groundspeed on a windy day.

The same things apply to aircraft, whether in the air or on the ground.

Do you agree?[/b]
Yes, but I said the aircraft is STATIONARY. Assuming no wind, it has no airspeed.

Top
#617644 - 31/12/06 11:42 AM 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
Great. On a windless day, if the engines are off the aircraft has neither airspeed nor groundspeed.

OK, now, let's place a conveyor belt under the aircraft's wheels, and bolt the plane to the ground by its nose, tail,and wingtips. Now, let's fire up the conveyor belt to 30mph.

It's still a windless day.
Answer these questions:
1) What's the aircraft airspeed?
2) What's the aircraft groundspeed?
3) What's the aircraft's wheelspeed on the conveyor?
_________________________
4x4 in uppercase is $X$!!!
1997 R50: VG33E/RE4R01A/TX10/3.7/R200A/ARB/4.636/H233B/ARB/4.636/321150R15

Top
#617645 - 31/12/06 11:53 AM Re: Know that if you do not post in this thread today the human race may cease to exist
BlueSky Offline
Member

Registered: 17/08/00
Posts: 2286
Loc: Georgia
Quote:
Originally posted by XPLORx4:
Great. On a windless day, if the engines are off the aircraft has neither airspeed nor groundspeed.

OK, now, let's place a conveyor belt under the aircraft's wheels, and bolt the plane to the ground by its nose, tail,and wingtips. Now, let's fire up the conveyor belt to 100mph.

It's still a windless day.
Answer these questions:
1) What's the aircraft airspeed?
2) What's the aircraft groundspeed?
3) What's the aircraft's wheelspeed on the conveyor?
1) Zero
2) Zero
3) I'm not sure what you mean. All over this thread, people have said "the wheels are turning at X MPH." But speed is a measure of movement, and the wheels aren't moving (except for rotation), so it should really be measured in RPM, right? Can you clarify please?

Top
#617646 - 31/12/06 12:06 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
The key is forward motion, which has everything to do with the tires because that's how the airplane - REGARDLESS OF HOW PROPELLED - moves across the ground.
Yes, the tires reduce the friction between the plane & the ground. But they do NOT propel, aka, cause the airplane's motion. They are only there to reduce friction w/ the ground.

Quote:

Let go of how the tires are being propelled (moved forward) and think of it this way: a tire rolling over a fixed surface results in forward motion. A non-VTOL (Vertical Take-Off/Landing) fixed-wing aircraft MUST have forward motion to achieve flight from a standing start.
You are correct. Except that an airplanes tire will not roll unless there is an outside force exerted, because they are not powered tires.

Quote:
On a runway, imagine the plane is sitting at point A on a straight line, with points B through Z representing the takeoff roll, Z being rotation (when the nose is lifted for takeoff).

Power is applied and that power - engine thrust - is converted into forward motion that takes the plane through points B to Z because again, a tire on the ground, regardless of HOW it is moved forward, covers a given distance for each revolution (i.e. forward motion). So if NYMadman's observer was standing alongside point A, the plane would leave him/her behind as it accelerated.
Yes. But listen carefully. The tires roll because the plane moves. The tires do not cause the movement. The tires could be fixed in place, with absolutely no rotation, and the plane can still move, aka, a float plane or a skid plane. The rolling tires only reduce the normal friction against the ground. They do not cause the plane to move.

Quote:
Distance traveled equals 2πR, where R is the wheel's radius. Let's just say the answer to that equation in our scenario is 12 feet. But the treadmill moves 12 feet in the opposite direction. The tires are attached to the plane, we can all agree on that, right? So if:

2πR = 12 feet but treadmill motion = -12 feet then the resulting forward motion is ZERO.
Wrong. If a treadmill moves 12 feet in REVERSE, the tires that are sitting on top of the treadmill move 12 feet FORWARD. Look at a simple gear setup. Place two gears in contact with each other. Now turn one gear. The other turns in the OPPOSITE direction.

So for your math problem, if the plane moved 12', that caused the wheels to move 12' FORWARD. If the conveyor moved 12' in REVERSE, it moves the wheels 12' FORWARD. The total distance the circumference of the tires have traveled is 24'.

Quote:
For the plane to move forward, 2πR MUST be greater than the distance the treadmill moves backward, but the scenario says the belt matches the plane's speed, so the result can't be greater than zero.

On a runway of course, there's no counter-motion backwards so 2πR is always greater than zero, resulting in forward motion.
Your math is wrong. See previous paragraph.

Quote:
In the scenario presented, points B through Z are on the treadmill, so as engine thrust is applied, it is NOT converted into forward motion because the treadmill accelerates as the thrust does.
No. The scenario states the treadmill accelerates as the PLANE accelerates. It does not say the treadmill matches the thrust. It says the conveyor matches the plane's speed. Thrust is not speed. Thrust is a force. Speed is a distance per unit of time. They are not the same thing. That's in the given initial conditions of the problem statement.

Quote:
Points A-Z simply pass under the plane, and it remains relatively stationary beside the observer, NOT leaving him/her behind.
Your visualiztion of the points means nothing. The plane has to move in order for the conveyor to move. If the plane is moving, then it's moving. There is no stationary plane that's also moving at the same time. There are only 3 dimensions in our physical world; if the plane is moving on a horizontal plane, it's either moving or its not. There is no possible way it can be moving and not moving at the same time...

Quote:
No relative wind (airflow over the wings), no lift, no takeoff.
There is airflow over the wings as the plane moves down the runway...

Quote:
For the "what if it was on perfect ice" argument, that doesn't fly (ha!) because even though the tires might not rotate, there is still forward motion when thrust is applied because the tires' purpose (reducing friction to allow relatively easy forward motion) has been eliminated by the ice's absence of friction. The plane would still cover points A to Z on the takeoff roll.
How can you possibly realize that the tires are only there to reduce friction to allow relatively easy forward motion in one sentence, yet still hold onto your belief that they propel the plane forward??? There are only two lines of thought here:

1) The engines provide horizontal force to propel the plane. The tires are there to reduce friction between the plane and the ground. (plane takes off)

or

2) The engines provide horizontal force to propel the plane through the air. The tires are there to propel the plane on the ground. (plane doesn't take off)

There is no other viewpoint for the solution. And if you believe #2, that the tires propel the plane on the ground, then you don't have a clue how an airplane works.

Remove the wings. Remove everything except the body, the engine attached to the body that provides the horizontal moving force, and the wheels that reduce friction. When that's the case, it doesn't matter what the ground is doing; whether it's moving or not doesn't matter, because the wheels are only reducing the friction between the ground and the main body of the vehicle.

Top
#617647 - 31/12/06 12:15 PM Re: Know that if you do not post in this thread today the human race may cease to exist
BlueSky Offline
Member

Registered: 17/08/00
Posts: 2286
Loc: Georgia
Once and for bloody all, I KNOW THAT AIRCRAFT WHEELS ARE NOT POWERED.

You're wrong when you say the belt causes the tires to "move" forward 12 feet. It causes the tires to ROTATE, not MOVE. And that's why the plane DOESN'T MOVE.

Top
#617648 - 31/12/06 12:19 PM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Bluesky, think about what you just posted.

Top
#617649 - 31/12/06 12:23 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 BlueSky:
It causes the tires to ROTATE, not MOVE.
EXACTLY!!!!!!!!!

The belt causes the wheels to ROTATE, not MOVE!!! And if it can't CAUSE the wheels to MOVE, then it CAN'T keep the wheels from moving, either!!!

So there is nothing the conveyor can do to prevent the aircraft from MOVING based on the force from the engines.

Top
Page 23 of 43 < 1 2 ... 21 22 23 24 25 ... 42 43 >



shrockworks xterraparts
XOC Decal