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Can a plane take off if the runway is moving under it in the opposite direction?


old man emu
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I know I said that some people so annoyed me that I was not going to participate on these forums again, but I can't break the addiction. Here's a question that will make you think.

 

If you put a plane on a conveyor belt that was moving in the opposite direction to the plane's take off direction and at the same speed as the plane's rotation speed, would the plane take off?

 

 

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The short and simple answer is that an aircraft is propelled through the air by the propeller or a jet engine, not it's wheels    The job of the wheels is to remove the friction between the ground and the aircraft. The tires and wheels being somewhat attached to the ground through friction would certainly turn faster but this force would not hold the aircraft back (other than a small amount of axle friction.)  

 

 

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OME you are scraping the bottom of a very old barrel now.

For the information of most of us, who haven't been visiting this forum for multiple years, this was a long debated topic, way back when Pontius was a student pilot.

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The only  effect of the conveyor belt moving backwards is that the wheel rotation speed will be double what it normally is at lift off.. The extra energy required would slow the acceleration of the plane to the required AIRSPEED a bit,  and the tyre may not take the extra rotational speed if it isn't rated for it. Nev

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The aircraft is not driven buy its wheels but by its propeller.  The wheels will spin on their axles but they will not hold the plane back in any way(other than a little axle friction).  The whole function of wheels on aircraft is to remove friction between the aircraft and the ground.   

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Thanks for the welcome back. Coming back is like falling off the wagon and landing in a den of iniquity. But there's more fun in the den than on the wagon! I think I'll stay over in this corner of the clubhouse and leave the technical side to the "experts". 

3 hours ago, spacesailor said:

My answer 

NO. If no headwind, no lift !.

I'm sorry that I didn't have the chance to say when I posed the question that the simplest situation was the nil wind one. If you go adding in wind it complicates and detracts from the basic idea. 

 

As Savage says, the trick of logic in the question is due to our experience with cars where the torque produced by the car engine is used rotate the driving wheels and the resistance to that motion which we call friction is what needs to be overcome to move the whole vehicle. With the aircraft, the engine torque is used to rotate the propeller which interacts with the air to move the aircraft forward.

 

But enough of this physics stuff. The answer is that the aircraft will take off.

 

 

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