will it take off?

[patrick_g]

Let us all remember that what makes an aircraft T A K E O F F is relative wind over the wings not how fast its wheels are turning or if it is moving forward over the terrain or backwards. When LIFT exceeds aircraft weight it takes off.

It is highly unlikely that the friction in the wheel bearings would be sufficient to generate a rearward motion force sufficient to exceed thrust by the margin required to prevent the aircraft from accelerating forward. (real world)

If however in your flight of fantasy problem statement the conveyor belt has unlimited speed and acceleration capabilities into relativistic realms the wheel bearings' friction could theoretically force the aircraft to remain motionless or go backwards. Likely real world bearings would fail but no big deal as if the conveyor belt can have "magic" bearings then why not the aircraft? If the aircraft's bearings are sufficiently low in friction then the aircraft will take off unless you want to accelerate your conveyor belt toward relativistic speeds and use the aircraft's wheel mass as something to ****** the aircraft's forward motion.

Given that the conveyor belt and the aircraft both have magic bearings the limiting factor will be the conveyor mechanism approaching relativistic speeds (in the limit, the speed of light.) Since the conveyor belt cannot exceed the speed of light its acceleration will approach zero in the limit. With no further acceleration the rotating aircraft wheels will no longer produce a retarding force and the aircraft will accelerate forward to take off.

It is possible that at some high speed the motion of the conveyor which pulls air with it forming a wind will at some high velocity provide a relative wind of sufficient velocity to generate sufficient lift to cause the aircraft to take off.


Patrick

 

[jimmysisson]

By golly, Patrick, you're right!

Jim

 

[MossRoad]

It is possible that at some high speed the motion of the conveyor which pulls air with it forming a wind will at some high velocity provide a relative wind of sufficient velocity to generate sufficient lift to cause the aircraft to take off.


Patrick

That ain't the only thing that generates sufficient wind..... :laughing:

 

[Egon]

No, no ,no; as the belt gets up to light speed it's mass is so great the plane sticks to it and gets dashed to smithereens on the rear roller.

 

[paulfun9]

Let us all remember that what makes an aircraft T A K E O F F is relative wind over the wings not how fast its wheels are turning or if it is moving forward over the terrain or backwards. When LIFT exceeds aircraft weight it takes off.

It is highly unlikely that the friction in the wheel bearings would be sufficient to generate a rearward motion force sufficient to exceed thrust by the margin required to prevent the aircraft from accelerating forward. (real world)

Simply put the plane will take off even with its wheels spinning backwards at what ever speed the conveyor is turning them. There would not be sufficient drag to hold it still. Now if the plane was dependent on the wheels to power it to take off speed then we would have a plane that couldn't attain takeoff speed.

 

[Fallon]

Proven by Mythbusters using models & an actual ultralight airplane. A plane will successfully take off from a conveyer belt moving at takeoff speed in the opposite direction.

MythBusters Episode 97: Airplane on a Conveyor Belt

 

[SPYDERLK]

Let us all remember that what makes an aircraft T A K E O F F is relative wind over the wings not how fast its wheels are turning or if it is moving forward over the terrain or backwards. When LIFT exceeds aircraft weight it takes off.

It is highly unlikely that the friction in the wheel bearings would be sufficient to generate a rearward motion force sufficient to exceed thrust by the margin required to prevent the aircraft from accelerating forward. (real world)

If however in your flight of fantasy problem statement the conveyor belt has unlimited speed and acceleration capabilities into relativistic realms the wheel bearings' friction could theoretically force the aircraft to remain motionless or go backwards. Likely real world bearings would fail but no big deal as if the conveyor belt can have "magic" bearings then why not the aircraft? If the aircraft's bearings are sufficiently low in friction then the aircraft will take off unless you want to accelerate your conveyor belt toward relativistic speeds and use the aircraft's wheel mass as something to ****** the aircraft's forward motion.

Given that the conveyor belt and the aircraft both have magic bearings the limiting factor will be the conveyor mechanism approaching relativistic speeds (in the limit, the speed of light.) Since the conveyor belt cannot exceed the speed of light its acceleration will approach zero in the limit. With no further acceleration the rotating aircraft wheels will no longer produce a retarding force and the aircraft will accelerate forward to take off.

It is possible that at some high speed the motion of the conveyor which pulls air with it forming a wind will at some high velocity provide a relative wind of sufficient velocity to generate sufficient lift to cause the aircraft to take off.


Patrick

Well summed.

Simply put the plane will take off even with its wheels spinning backwards at what ever speed the conveyor is turning them. There would not be sufficient drag to hold it still. Now if the plane was dependent on the wheels to power it to take off speed then we would have a plane that couldn't attain takeoff speed.

No evidence that you understand the composite of what Patrick wrote. ... Simplism will not get you there.
.,,larry

 

[Egon]

Will a plane with jet propulsion take off?

 

[SPYDERLK]

Will a plane with jet propulsion take off?

Same principles apply if you are relying on forward motion to get air over the wing. ... Conceivable that a big tail mounted jet engine could suck enuf air over the wing to levitate a light airframe.

 

[paulfun9]

Well summed.

No evidence that you understand the composite of what Patrick wrote. ... Simplism will not get you there.
.,,larry

No evidence needed. Everyone is tryin to make a simple problem hard by adding magical bearings and such. Get real the plane will take off and it has been proven with an actual conveyor and a remote control plane. This question has been beat to death over the years since I was a kid but yet so many keep trying to make it a hard problem.