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11-26-05, 07:43
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#1 (permalink)
| | Now with twice the head
Scottwax is offline
Join Date: Oct 2001 Location: Arlington, TX Posts: 25,603 | Can someone answer this question?
A plane is standing on runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).
The question is:
Will the plane take off or not? Will it be able to run up and take off? | |
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11-26-05, 07:57
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#2 (permalink)
| | Registered User
Setec Astronomy is offline
Join Date: Jul 2004 Location: New Jersey Posts: 7,656 | No, it won't, because it's airspeed is zero.
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11-26-05, 08:12
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#3 (permalink)
| | Registered User
Mike-in-Orange is offline
Join Date: Jul 2005 Posts: 221 | Quote: |
Originally Posted by Setec Astronomy No, it won't, because it's airspeed is zero. | Dead on. The wheels may be spinning but without proper airspeed over the wings it will never generate lift and therefore never leave the ground.
Similarly, in theory, if you tethered the plane so it couldn't move and placed in front of it a fan large enough to move the needed air over the wings to generate lift, the plane would get off the ground yet still not move due to a lack of forward thrust. | |
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11-26-05, 08:38
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#4 (permalink)
| | Turbo Detailer
DARKSTI is offline
Join Date: Oct 2004 Location: Reno Posts: 569 | yeap it wont be moving againt the air so it cant create lift or drag.
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Originally Posted by DocHoliday I recently had SSR2.5 on toast for breakfast, was tasty and it polished my teeth! |  | |
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11-26-05, 09:09
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#5 (permalink)
| | I don't have much to add
SpoiledMan is offline
Join Date: Mar 2004 Location: Southern Cali Posts: 6,664 | Yep, no lift, no flight.
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11-26-05, 09:33
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#6 (permalink)
| | Registered User
Black240SX is offline
Join Date: Oct 2004 Location: Victoria, Canada Posts: 577 | Another question. If you had a big-*** wing on your car and were going fast enough, could you drive on an inverted road?
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11-26-05, 09:38
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#7 (permalink)
| | Turbo Detailer
DARKSTI is offline
Join Date: Oct 2004 Location: Reno Posts: 569 | Quote: |
Originally Posted by Black240SX Another question. If you had a big-*** wing on your car and were going fast enough, could you drive on an inverted road? | if you had enough power and were light enough. F1 cars are thought to be able to do it. But they are super light and have lots of power and down force.
__________________ Quote: |
Originally Posted by DocHoliday I recently had SSR2.5 on toast for breakfast, was tasty and it polished my teeth! | | |
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11-26-05, 09:48
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#8 (permalink)
| | I don't have much to add
SpoiledMan is offline
Join Date: Mar 2004 Location: Southern Cali Posts: 6,664 | If it generates enough down force to exceed it's weight it should, in theory, be able to invert.
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The Power of Dreams... Club FLEX Member
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Yes, I *do* use grout sponges! | |
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11-26-05, 11:31
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#10 (permalink)
| | Registered User
Black240SX is offline
Join Date: Oct 2004 Location: Victoria, Canada Posts: 577 | lol
I originally thought that it would not take off, but after reading some of the 14 pages on the subject at the physics forum, I've changed my mind. It will take off!
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11-27-05, 12:03
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#11 (permalink)
| | I don't have much to add
SpoiledMan is offline
Join Date: Mar 2004 Location: Southern Cali Posts: 6,664 | After rereading the question and taking a look at the forum, I was under the wrong impression. I didn't understand that the plane would be using engine power and because of that the wheel speed doesn't matter. Yes, it will take off.
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The Power of Dreams... Club FLEX Member
Black cars are fun!
Yes, I *do* use grout sponges! | |
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11-27-05, 06:31
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#12 (permalink)
| | Registered User
wlhump is offline
Join Date: Jul 2002 Posts: 42 | The fact that the "ground" is moving the the opposite direction is moot. The airplane is reacting to the fact that the jet is creating thrust out the engines. The wheels are not powered and therefore do not need to interface with the ground in the smallest amount. In essence, the wheels only hold the plane up and reduce the friction of it as it moves down the runway.
Think about it this way.... The plane is already airborne. This eliminates the entire effect of the "moving runway." Does it fall out of the sky? Of course not because the thrust created by the expulsion of the hot gasses out the back of the engines are greater than the resistance to move the plane forward. Newton's law: "For every action, there is an equal and opposite reaction" is what drives the plane forward. A moving runway has nothing to do with the scenario.
I have to go to this physics forum and see the arguments. It should be interesting. | |
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