Mythbusters to take on - PLANE ON A TREADMILL!!!

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tgrayson said:
I should quit while I'm ahead. :) What I said goes for gliders as well, because they're also pulling themselves ahead through the air, but just using gravity to do so. However, their angle of descent with respect to the ground would steepen when the groundspeed decreases. The IAS would remain the same, because the airplane isn't aware of the groundspeed. If you were inside the airplane and couldn't see the ground, you'd have no way to know whether there was a wind or not.
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hhaa. well, my point is, with the glider, that it does not accelerate itself through the atmosphere, so if (whichever direction it was flying) the air around it moves as fast as it does, it would simply drop. ofcourse when its in a dive, it picks up airspeed and creates lift.. but i was thinking one dimensionally.. should have made myself more clear.
 
gevo said:
hhaa. well, my point is, with the glider, that it does not accelerate itself through the atmosphere, so if (whichever direction it was flying) the air around it moves as fast as it does, it would simply drop. ofcourse when its in a dive, it picks up airspeed and creates lift.. but i was thinking one dimensionally.. should have made myself more clear.
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My point was that this doesn't happen with a glider either. If it did, you could tell which way the wind was coming from, and you can't. The only thing that power does is allow the airplane to maintain altitude.

The physics is the same as if you tossed a ball while riding on a train. No matter which way you tossed it, the velocity would be the same. It would not be affected by the train's velocity.
 
tgrayson said:
The physics is the same as if you tossed a ball while riding on a train. No matter which way you tossed it, the velocity would be the same. It would not be affected by the train's velocity.
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Only true regarding velocity relative to the person on the train, not true from the perspective of someone standing beside the tracks.
 
Wait, is this one of the awful word problems from math class that you're supposed to "draw a picture" to help with?!


*shudder* Bad flashbacks to jr. high math there......
 
tgrayson said:
The physics is the same as if you tossed a ball while riding on a train. No matter which way you tossed it, the velocity would be the same. It would not be affected by the train's velocity.
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It would not be affected only if the velocity of the train was constant.
 
skidz said:
It would not be affected only if the velocity of the train was constant.
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Partially right, it is always affected in the eyes of a stationary observer. For someone on the train, the velocity is not affected by the motion of the train if the motion is constant.
 
Captain_Bob said:
I myself learned long ago to never argue with... "The Gray One..." ;)

Bob
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oh.. I am not arguing, i totally agree with him.. If i had made that mistake on an exam, i would have commited suicide.. lol...

basically, Gray, its an issue of the relative speed of the air over the wings, with relation ONLY to the wings.. if we agree on this, we're good..
 
gevo said:
basically, Gray, its an issue of the relative speed of the air over the wings, with relation ONLY to the wings.. if we agree on this, we're good..
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That sounds good, but I'm still skeptical you're convinced. ;)

BTW, this is perpetually a problem in aviation circles, most famously in the myth of the "Downwind Turn." Even people with enough experience to know better will often attribute an airspeed deviation to a tailwind or a headwind.

I've had students fly each cardinal direction on a windy day to demonstrate the IAS is the same in each direction, yet they still have trouble accepting this truth.
 
I dont think I get it...

I take it as the airplane is sitting on the treadmill and the engine is full throttle pulling the airplane at lets say a hypothetical 55 kts. They simply crank up the treadmill to 55kts so the airplane is not moving forward?

Am I reading this correct? If I am then it is the stupidest thing I have seen, an airplane without relative airflow going over the airfoil can not become airborne.

that is too easy though so I think I am reading it wrong. If however they stuck it in a wind tunnel and blew 55 knots of wind its way then it would become airborn providing you increased the the angle of attack to anything other then the aifoils critical angle of attack (stall speed) It is the same princible as the super cubs that take off in 6 feet, they simply point into an intense headwind, go full power and can lift the tail and rotate because the relative wind over the airfoil is enough to maintain lift and the tail has been lifted bringing the angle of attack to something less than the critical angle.

does this make any sense? im tired
 
USMC-SGT said:
I dont think I get it...

I take it as the airplane is sitting on the treadmill and the engine is full throttle pulling the airplane at lets say a hypothetical 55 kts. They simply crank up the treadmill to 55kts so the airplane is not moving forward?

Am I reading this correct? If I am then it is the stupidest thing I have seen, an airplane without relative airflow going over the airfoil can not become airborne.

that is too easy though so I think I am reading it wrong. If however they stuck it in a wind tunnel and blew 55 knots of wind its way then it would become airborn providing you increased the the angle of attack to anything other then the aifoils critical angle of attack (stall speed) It is the same princible as the super cubs that take off in 6 feet, they simply point into an intense headwind, go full power and can lift the tail and rotate because the relative wind over the airfoil is enough to maintain lift and the tail has been lifted bringing the angle of attack to something less than the critical angle.

does this make any sense? im tired
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thats exactly it... if the treadmill matches the forward motion of the plane, well... she ain't going anywhehre unless there is a 55 knot headwind lol
 
USMC-SGT said:
I dont think I get it...

I take it as the airplane is sitting on the treadmill and the engine is full throttle pulling the airplane at lets say a hypothetical 55 kts. They simply crank up the treadmill to 55kts so the airplane is not moving forward?

Am I reading this correct? If I am then it is the stupidest thing I have seen, an airplane without relative airflow going over the airfoil can not become airborne.

<SNIP>

does this make any sense? im tired
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Yes, you are reading that right. The not-clearly-stated premise behind the "riddle", and the source of thousands of wasted posts and heated discussions, is that somehow the treadmill would actually able to affect the velocity of the airplane.

Yes, if say, you removed the wheels and then bolted the gear legs to the treadmill, it could prevent the aircraft from taking off.

In actuality, no.
 
What I'm curious about is how mythbusters is going to do this....

man, I still can't comprehand how some people do not understand this....
 
tgrayson said:
Yes, that's the context of the discussion. An inertial frame of reference.
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Ditto, and in essence steady velocity of train = steady wind (i.e. no wind shear, etc.)

Not sure where the confusion in this thread is coming from. I thought we were all pilots. :confused:
 
USMC-SGT said:
I dont think I get it...

I take it as the airplane is sitting on the treadmill and the engine is full throttle pulling the airplane at lets say a hypothetical 55 kts. They simply crank up the treadmill to 55kts so the airplane is not moving forward?
Click to expand...

taseal said:
thats exactly it... if the treadmill matches the forward motion of the plane, well... she ain't going anywhehre unless there is a 55 knot headwind lol
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Both of you, turn in your wings NOW!! :banghead:
 
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