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Verified Tsikot Member
- Join Date
- Jul 2005
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- 199
November 10th, 2006 11:20 AM #91naku! hindi pa pala tapos ito.
ok am gonna say it again..."imposible yun"...just like my previous example..if you are going to pull a table cloth from underneath a plate or a glass without toppling or moving it, you have to pull it quickly. right?...try doing pulling it slowly and chances are the plate or glass will move together with the table cloth...malinaw ba yun? what is your conclusion therefore? the faster the movement of the cloth the more chances the plate will stay in place... the darn plate dont even have wheels!!!
now, how are you gonna keep a plane from moving forward, move the conveyor slowly?
the problem is we were given a wrong premise that it is possible...you accept that premise most likely your answer/conclusion will also be wrong..agree?
"the conveyor will match the speed of the plane, instantly"... jeez! you believe that?! what do i think? if i'm going to believe what you guys are saying that the plane would be stationary then the conveyor would not even move! why? e di kayo narin dapat sumagot...remember its the plane's speed that we are talking about and not the rotation/movement of the wheels.
again, the plane's wheels are not powered, they will only move if the plane will move..and also in this case if the tarmac/conveyor will move...they have nothing to do with the plane's propulsion..given enough thrust the plane will move forward with or without wheels (sira nga lang underbelly/fuselage )...some hydro planes dont have wheels hehe! (joke!) (here you can use artificial wave making machine instead of conveyor belt )
my conclusion:
1. the plane will be able to take-off.
2. indeed its very easy to make things complicated...its genius to make them simple.
3. salvaje si otep..hehehe!
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November 10th, 2006 11:46 AM #92
nahilo ako sa mga response...wala namang ganung runway di ba? na isahan naman tayo ni doc...
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Tsikot Member Rank 4
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- Oct 2002
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- 2,716
November 10th, 2006 12:08 PM #93Let's see your FBD then.
Major flaw: The runway friction and engine thrust spin the wheels in the SAME direction, not in opposite directions. Try mo pa sa matchbox on a tablecloth. The only opposing force acting on the wheels is the friction of the wheelbearings, which is constant (unlike engine thrust) as well as negligible.
Obviuosly, Fb, being off-center, produces torque which tends to rotate the wheel. Friction force is always against motion, if the wheel tends to move forward with Ff, then Fb will try to oppose it.
The friction on the wheel bearing is basically negligible and because of this, the wheel is allowed to rotate. When the wheel rotates, it will move forward (and the plane flies) IF the runway is not moving. With a moving runway, the forward motion of the wheel is exactly opposed, hence the wheel, although rotating, stays in place.
In the FBD, a moving runway is depicted as Fb being significant to oppose Ff. If Fb is made greater than Ff, then the wheel/plane would be moving backward! (meaning, the conveyor/runway was adjusted too fast!)
The wheel bearing, with almost zero friction, actually plays an important role of the wheel. It is its frictionless property that allows the wheel to move along the road. But with a moving runway, it is also its frictionless property that allows the wheel to stay in place while rotating.
We're not concerned about forces acting on the wheels, we consider the forces acting on the plane itself. The big force acting against the plane is wind resistance, not friction from the ground. Remember, the wheels are designed to freewheel.
It's not the runway that's frictionless, it's the wheel bearings as far as this problem is concerned.
If the wheel bearings got stuck, the plane will not move if the runway does not move; the plane will move backwards with a moving runway (even if the engines are at full thrust).
Again, runway speed = plane speed (for the nth bloody time) does NOT imply runway force ACTING ON THE PLANE = engine thrust.
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November 10th, 2006 12:16 PM #94
i stand by my answer that the plane WILL NOT TAKE OFF.
the jet engine is just like a vacuum cleaner upfront. it sucks in air, which means all the air will go straight into the turbine and NOT PASS UNDER THE WINGS which CREATES THE LIFT necessary for the airplane to take off.
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Tsikoteer
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November 10th, 2006 12:18 PM #95
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November 10th, 2006 12:35 PM #97
Okay, read my post again.
Now, go buy a torque wrench, a matchbox car, and find an electric treadmill.
I will do this experiment myself when I have the time, and I will film it for all of you.
[size=4]For the treadmill to keep the plane from moving forward, it must exert x force on the plane, where x is directly proportional to the speed of the plane and treadmill.[/size]
Thus, for every y mph FASTER the treadmill goes, it must exert x times y amount of force on the airplane to keep it from moving forward and thus, achieving take-off speed.
But you'll find, with your handy-dandy torque wrench (hell, if you can't buy one, get a hanging weighing scale from the wet-market, and tie it to the car), that the force exerted by the treadmill on a wheeled vehicle is not related to the speed of the treadmill in a linear fashion.
[size=4]It will exert roughly the same amount of force on the wheeled vehicle at 1 mph or 100 mph.[/size]
I'm sorry... this is getting seriously silly. All of you go out NOW and find a treadmill and a weighing scale. Then come back and apologize. :hysterical:
[size=1]OTEP!!! May utang ka nang beer sa akin!!!!!!!!!![/size]
Ang pagbalik ng comeback...
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November 10th, 2006 12:39 PM #100
*Kinyo: wheel speed does NOT equal airplane speed.
The airplane is not wheel driven. The wheels can be moving 1000 mph along the conveyor, and the plane will still be going at the same speed it would be going if the wheels were moving at 50.
Your analogy on the wheel plane thing is false.
If the wheel moves, the plane moves, right?
If the runway moves, does the wheel move? NO. The Wheel is not attached to the runway.
[size=4]This is the tablecloth trick. The tablecloth is the runway, the wheeled plane is a plate on the table. Pull the runway out from under the plane fast enough, and it won't move.[/size]
Now do you understand?
Ang pagbalik ng comeback...
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