RE: Seriously now, can it take off or not? What do you think?

RE: Seriously now, can it take off or not? What do you think?
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[Poll]

Seriously now, can it take off or not? What do you think?

Yes, it will take off.

69% (61)

No, it won't take off.

30% (27)

Total Votes : 88

(last vote on : 8/21/2007 11:55:01 PM)
(Poll will run till: -- )

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RE: Seriously now, can it take off or not? ... - 12/14/2005 8:51:49 PM

w_benjamin

Posts: 81
Joined: 12/12/2005
From: , NH, USA
Status: offline

"If the conveyor is set to match the 'rotational speed' of the wheels.. as the airplane moves forward.. the belt will in turn mov forward to keep the wheels rotational speed at 0rpm, as that is the 'current speed of the wheel'. remember the conveyor is set to match the rotation of the wheel.. the wheel is not rotating unless the belt moves in relation to the wheel. "

A couple of problems with this. First, the conveyor rotates in the opposite direction. To visualize this, think of two gears meshed together. When one moves clockwise, the other moves counter-clockwise. Second it is not the wheel that rotates in relation to the belt..., it is the belt that rotates in relation to the wheel. I give you credit for trying to think it through though.

(in reply to gtmattz)

Post #: 276

RE: Seriously now, can it take off or not? ... - 12/14/2005 8:53:38 PM

MinnFlyer

Posts: 19374
Joined: 4/22/2002
From: Willmar, MN, USA
Status: offline

Yes yes yes, he read it wrong. We figured that one out already.

Now, Answer my question

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to w_benjamin)

Post #: 277

RE: Seriously now, can it take off or not? ... - 12/14/2005 8:58:19 PM

David Cutler

Posts: 2163
Joined: 9/13/2002
From: Los Angeles, CA, USA
Status: offline

quote:

Since pushing the wheels has no effect on the takeoff of the plane, they should take off in the same distance, right?

No, because there is now rolling resistance that the sand has introduced into the situation. The sand absorbs energy because it is soft and energy is needed to distort it. The hard ashphalt surface (moving or not) doesn't, so therefore doesn't provide resistance. (except, yet again, for the very small bearing friction and inertia of the wheel itself).

The fact that you asked that tell me you haven't really grasped the forces that are around.

-David C.

(in reply to w_benjamin)

Post #: 278

RE: Seriously now, can it take off or not? ... - 12/14/2005 8:58:28 PM

gtmattz

Posts: 64
Joined: 11/14/2005
From: Winnemucca, NV, USA
Status: offline

quote:

ORIGINAL: w_benjamin

"If the conveyor is set to match the 'rotational speed' of the wheels.. as the airplane moves forward.. the belt will in turn mov forward to keep the wheels rotational speed at 0rpm, as that is the 'current speed of the wheel'. remember the conveyor is set to match the rotation of the wheel.. the wheel is not rotating unless the belt moves in relation to the wheel. "

A couple of problems with this. First, the conveyor rotates in the opposite direction. To visualize this, think of two gears meshed together. When one moves clockwise, the other moves counter-clockwise. Second it is not the wheel that rotates in relation to the belt..., it is the belt that rotates in relation to the wheel. I give you credit for trying to think it through though.

Wait... where does it say the belt can only move one direction?

the belt is set to match the rotational speed of the wheels. right? well.. if the wheels start out not rotating.. what keeps the belt from moving with the airplane to match the wheels initial rotational speed????

And btw... what did I read wrong?

here is the original question again.. please read it:

quote:

Imagine an airplane is on the beginning of a massive conveyor belt, as wide and as long as a runway, and intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.
There is no wind.

Can the plane take off?

where in that statement does it say that the belt can only move in one direction? it states it is set to match the exact rotation of the wheels at any time...

the wheels start out not rotating.. the airplane accelerates.. the belt moves with the plane to match the 0 rotation of the wheels???

thats what I see happening.

< Message edited by gtmattz -- 12/14/2005 9:05:08 PM >

(in reply to w_benjamin)

Post #: 279

RE: Seriously now, can it take off or not?... - 12/14/2005 9:00:27 PM

w_benjamin

Posts: 81
Joined: 12/12/2005
From: , NH, USA
Status: offline

Y'know, I have answered your questions. Check out post 191, 194, 199(for the SAME question), and finally post 238 and 243.

(in reply to w_benjamin)

Post #: 280

RE: Seriously now, can it take off or not? ... - 12/14/2005 9:02:58 PM

MinnFlyer

Posts: 19374
Joined: 4/22/2002
From: Willmar, MN, USA
Status: offline

No you didn't, you typed a bunch of hypothetical nonsense.

YES or NO????

You have accused me of not being able to read, now show me how smart you are.

YES, or NO????

Pick one

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to w_benjamin)

Post #: 281

RE: Seriously now, can it take off or not?... - 12/14/2005 9:04:39 PM

w_benjamin

Posts: 81
Joined: 12/12/2005
From: , NH, USA
Status: offline

"the belt is set to match the rotational speed of the wheels. right? well.. if the wheels start out not rotating.. what keeps the belt from moving with the airplane to match the wheels initial rotational speed???? " When the wheels are not in motion the conveyor is not in motion. When the wheels are in motion, they are rotating in the opposite direction from the conveyor. so when the wheels roll in a forward rotation, the conveyor rotates in a backwards rotation.

(in reply to w_benjamin)

Post #: 282

RE: Seriously now, can it take off or not?... - 12/14/2005 9:07:15 PM

w_benjamin

Posts: 81
Joined: 12/12/2005
From: , NH, USA
Status: offline

Sorry about putting the "uhh," in front of NO in post 243. Must'a thrown ya off with that hypothetical nonsense in 'uhh'.

(in reply to w_benjamin)

Post #: 283

RE: Seriously now, can it take off or not?... - 12/14/2005 9:08:37 PM

gtmattz

Posts: 64
Joined: 11/14/2005
From: Winnemucca, NV, USA
Status: offline

quote:

ORIGINAL: w_benjamin

"the belt is set to match the rotational speed of the wheels. right? well.. if the wheels start out not rotating.. what keeps the belt from moving with the airplane to match the wheels initial rotational speed???? " When the wheels are not in motion the conveyor is not in motion. When the wheels are in motion, they are rotating in the opposite direction from the conveyor. so when the wheels roll in a forward rotation, the conveyor rotates in a backwards rotation.

why should they ever rotate? the belt matches the speed.. they move at 0 rpm.. the belt moves to match that 0 rpm.

whatever, i think some people just like to argue and once they have an idea in their head they cannot change their view to accept that their idea may possibly be wrong..

I am 99% certain that what I have come up with is a viable solution to this little problem.. I will argue no more.

(in reply to w_benjamin)

Post #: 284

RE: Seriously now, can it take off or not?... - 12/14/2005 9:10:57 PM

David Cutler

Posts: 2163
Joined: 9/13/2002
From: Los Angeles, CA, USA
Status: offline

quote:

ORIGINAL: w_benjamin

"the belt is set to match the rotational speed of the wheels. right? well.. if the wheels start out not rotating.. what keeps the belt from moving with the airplane to match the wheels initial rotational speed???? " When the wheels are not in motion the conveyor is not in motion. When the wheels are in motion, they are rotating in the opposite direction from the conveyor. so when the wheels roll in a forward rotation, the conveyor rotates in a backwards rotation.

All true.

As we have now said about 2,756,845 times, why are you fixated on the wheels when they have nothing to do with the motion of the plane (rolling resistance excluded as there isn't much to take into account on a hard surface)?

The wheels can be rotation at whatever speed the belt lets them, and it STILL won't affect the speed of the plane.

Say 100 times. "There is no friction to speak of from the wheels that retard the motion of the plane!"

-David C.

(in reply to w_benjamin)

Post #: 285

RE: Seriously now, can it take off or not?... - 12/14/2005 9:12:32 PM

w_benjamin

Posts: 81
Joined: 12/12/2005
From: , NH, USA
Status: offline

I find it interesting, Minnflyer, that you used a scenario that does not reflect the question, yet may reflect your perception of the question. You're pulling a board out from under the planes wheels in your scenario. That makes the board the actor and the wheel the reactor. In the question they are the other way around, and they can't be interchanged.

(in reply to w_benjamin)

Post #: 286

RE: Seriously now, can it take off or not?... - 12/14/2005 9:16:04 PM

David Cutler

Posts: 2163
Joined: 9/13/2002
From: Los Angeles, CA, USA
Status: offline

quote:

ORIGINAL: w_benjamin

I find it interesting, Minnflyer, that you used a scenario that does not reflect the question, yet may reflect your perception of the question. You're pulling a board out from under the planes wheels in your scenario. That makes the board the actor and the wheel the reactor. In the question they are the other way around, and they can't be interchanged.

Have you said 100 times that there is no connection between the speed of the wheels and the airspeed yet?

You can talk about the belt, wheels etc until the cows come home, and be both right and wrong about it. It still doesn't change the fact that it is irrelevant.

-David C.

(in reply to w_benjamin)

Post #: 287

RE: Seriously now, can it take off or not?... - 12/14/2005 9:16:11 PM

w_benjamin

Posts: 81
Joined: 12/12/2005
From: , NH, USA
Status: offline

"The wheels can be rotation at whatever speed the belt lets them, and it STILL won't affect the speed of the plane." Again, we come to the misconception in the question. The belt DOES NOT act on the wheels, therefore the wheels don't rotate at 'whatever speed the belt lets them'. It's the OTHER WAY AROUND.

(in reply to w_benjamin)

Post #: 288

RE: Seriously now, can it take off or not?... - 12/14/2005 9:17:57 PM

David Cutler

Posts: 2163
Joined: 9/13/2002
From: Los Angeles, CA, USA
Status: offline

quote:

It's the OTHER WAY AROUND.

. . and still irrelevant to the airspeed of the aircraft, which is what matters in flight.

-David C.

(in reply to w_benjamin)

Post #: 289