Off-Topic Brain Teaser ... will the plane take off ?

Discussion in 'Off-Topic Chat' started by SpeedyGee, Friday 14th Mar, 2014.

?

Will the plane take off

  1. Yes (ouch my head hurts)

    4 vote(s)
    30.8%
  2. No (ouch my head hurts)

    7 vote(s)
    53.8%
  3. Yes (wild guess)

    2 vote(s)
    15.4%
  4. No (wild guess)

    0 vote(s)
    0.0%
  5. I have no idea, Im outta here

    0 vote(s)
    0.0%
  1. SpeedyGee Administrator Staff Team

    England Speedy Birmingham
    14,999
    5,591
    4
    Read this brain teaser on another forum and now it's keeping me awake LOL

    A plane is standing on a runway that is made of a large conveyor belt. The plane fires up its engines, but as it moves forward, the conveyor belt senses the speed of the plane's wheels and moves at exactly the same speed in the opposite direction. Can the plane take off?
     
    Loading...
  2. Ichiban Founder Staff Team

    England CJ Leeds
    30,102
    6,369
    516
    Thrust of the engine will be sufficient to over come the conveyor belt.. I think
     
    Loading...
  3. naslam968 Club Member ★ ☆ ☆ ☆ ☆

    London
    132
    18
    1
    I second Ichiban.
     
    Loading...
  4. DeviateDefiant Co-Founder Staff Team

    United Kingdom Leo Northants
    9,206
    2,976
    3
    No, lift-off is achieved because the faster moving air over the top of the aerofoil surface causes less resistance than the slower moving air going underneath, which means air pressure is higher on the underside and the plane is lifted upwards.

    If the plane is effectively standing still with its wheels spinning on the spot because of the conveyor belt - unless that belt itself was forcing the wind along with its motion, the reaction which causes the plane to lift-off is not present.
     
    Loading...
  5. Ichiban Founder Staff Team

    England CJ Leeds
    30,102
    6,369
    516
    you read that up didn't you!:Ermm:
     
    Loading...
  6. SpeedyGee Administrator Staff Team

    England Speedy Birmingham
    14,999
    5,591
    4
    Google is a developers best friend :Smile:
     
    Loading...
  7. DeviateDefiant Co-Founder Staff Team

    United Kingdom Leo Northants
    9,206
    2,976
    3
    How else did you guys think a plane lifted off? Haters gonna hate:Icecream:
     
    Loading...
  8. SpeedyGee Administrator Staff Team

    England Speedy Birmingham
    14,999
    5,591
    4
    Actually I think if you did Google it you will find conflicting views :Messed:

    I'm with DD on this one.:Whoosh:
     
    Loading...
  9. DeviateDefiant Co-Founder Staff Team

    United Kingdom Leo Northants
    9,206
    2,976
    3
    I just remember learning about aerofoils in our Design/Workshop classes in school, we had to attempt to replicate them out of Styrofoam :Whistle:
     
    Loading...
  10. Racy Jace Expert Advisor ★ ★ ★ ★ ★

    I think the plane takes off but the wheels are stationary as the convey belt is literally following the plane along with the thrusters moving the plane forward. If the conveyor belt went the other way it would still take off but the wheels would be at 2x the speed of plane. Plane takes off regardless as long as the thrusters get up to normal take off speed.
     
    Loading...
    PeteMM likes this.
  11. Racy Jace Expert Advisor ★ ★ ★ ★ ★

    I hope we get an answer to this and it's not just posted to make us go loopy.
     
    Loading...
  12. road-assassin Junior Member ☆ ☆ ☆ ☆ ☆

    UK
    12
    If it is not moving then there is no lift, no lift to flying. (Didn't use google, i'm studying engineering)
     
  13. SpeedyGee Administrator Staff Team

    England Speedy Birmingham
    14,999
    5,591
    4
    I'm loopy already Jace, so I just wanted the rest of you to join me LOL

    Keep the theories rolling in guys, No vote is winning by a small margin on the poll.
     
    Loading...
  14. PeteMM Premium Member Club Supporter

    Northern Ireland Pete Belfast, UK
    854
    454
    Yes it will take off, the wheels can stay still as the conveyor rolls towards/away from it.

    The wheels are not what propels the aircraft forwards, so logically providing they are directing the plane in the right direction, the thrust will allow the aircraft to pick up speed and take off as per normal.

    In the same way, the plane can be travelling at 600mph with the wheels not turning at all.

    As such, the wheels/conveyor belt speed have little to no impact on whether or not the aircraft moves forwards, the only limiting factor might well be the bearings in the landing gear being able to cope with twice the normal rate of wheel speed for a prolonged period of time prior to taking off.

    As an Airframe Engineer by trade, I am pretty certain I am correct here.

    The conveyor belt can go in either direction at whatever rate it pleases, providing the pilot can still remain in control of the leading wheels and subsequently his steering that bad boy is taking off

    To explain this, you could turn the conveyor belt on, tie a rope to the plane and strop it to the ground and the wheels will turn with zero effect on the aircrafts position whether longitudinally, laterally or vertically. Once again, wheel speed and conveyor belt speed has zero impact on the aircraft itself.

    If the conveyor belt wants the wheels to remain stationary, as the airspeed increases with the aircraft moving forwards, the conveyor will be moving in the same direction as the aircraft to prevent the wheels from turning at all, with that in mind, an aircraft is perfectly capable of accelerating and decelerating in mid air without any wheel movement, so it definitely will take off, perhaps earlier than normal as there will be little/no rolling resistance between the landing gear and the ground beneath it, all that work and energy has been removed from the aircraft components and is now being done by the conveyor belt to allow the wheels to remain stationary.

    On the other hand, the conveyor could go against the aircraft direction of travel. The only difference between this and the above is that the wheel speed experienced during a normal take-off will now be doubled, but it will not impede the progress of the aircraft taking off as the wheels serve only 4 purposes - they allow the aircraft to be moved by means other than jet or propellor propulsion and they allow precise steering when on the ground and not relying on air speed over a control surface and of course they allow the aircraft to go through the transition of being airbourne to being grounded without turning into a ball of flames every time. Last but not least, they provide consumable component to use as a form of retardation when landing, taxiing and parking.

    They do not provide any form of powered travel, and therefore bare NO relation to whether the aircraft will take off or not!
     
    Last edited: Friday 14th Mar, 2014
    Loading...
    Racy Jace likes this.
  15. Racy Jace Expert Advisor ★ ★ ★ ★ ★

    What your referring to is the wheels not moving. You've got to remember it's on a conveyor belt which does move. The wheels don't make a plane take off, the engine does. It's not like it's got a drive shaft. It would take off even if It was on ski's
     
    Loading...
    PeteMM likes this.
  16. Racy Jace Expert Advisor ★ ★ ★ ★ ★

    I think we need to build a model to recreate this theory like Doc Brown in back to the future.
     
    Loading...
  17. SpeedyGee Administrator Staff Team

    England Speedy Birmingham
    14,999
    5,591
    4
    Interesting stuff @PeteMM

    So at what point would the co-pilot say "rotate" ?

    The wings need airflow over them to create the lift. So normally this done by propelling the aircraft along the ground until the speed of the airflow is sufficient to enough to create the lift. In this case the airplane is basically stationary and all the work the thrusters are doing is being undone by the belt going the opposite direction.