Airplane + Conveyor Belt
- Started
- Last post
- 74 Responses
- jakeyj
The discussion has been going on for ages, and any time someone mentions the words "airplane" or "conveyor belt" everyone starts right back up. Here's the original problem essentially as it was posed to us: "A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"
- prophet0NE0
isn't it a matter of wind resistance which would require the plane to move forward?
- mrdobolina0
ask Discipler.
- jakeyj0
i vote no
- t_rock0
I would say yes, as it should be the required force from the engine thrust which enables the plane to fly. If you acheive that force then you should be able to take off. An aircraft carrier utilises a winch/slingshot system to shorten the length needed to acheive the speed for takeoff... in this case the length is shortened to point of virtually standing still.
- planet010
the jets propel the plane, the wheels don't drive it. the conveyer belt can spin the opposite direction as fast as it wants, it won't matter. the plane is still going to pull itself forward through the air.
- prophet0NE0
i'd say it would fly because the wings require the bernoulli effect to achieve lift, which wouldn't occur if the plane remained stationary.
http://scienceworld.wolfram.com/…
my physics knowledge is limited to watching bill nye the science guy and mythbusters, so...
- prophet0NE0
i meant "wouldn't fly". see i can't even spell.
- todelete__20
no it would not be able to take off.
if the planes takeoff speed is 150mph and the conveyor can match that speed, the plane would actually not be moving on the belt.
just as a person doesn't move on a treadmill.
air pressure flowing over the wings is what makes a plane fly. if there is no air flowing over the plane it won't take off.
thus. no.
- wankerbez0
OM f-ing god
are you guys really trying to figure this out!!!it would be the same as having the brakes on!!!!!!!!!!!!!!!!
morons, how do you think they test the engines on the ground?
- ribit0
OMG..
the wheels are freewheeling.. it will take off fine and wont even notice that the ground is moving..they test engines on the ground by immobilising the plane (brakes on/fixed ground)... moving the ground beneath free-wheeling wheels doesnt do that.
(i hope everyone here is taking the piss)
- prophet0NE0
so the plane lifts without air moving around the wings?
- ribit0
no...the plane moves forward as it is spewing lots of hot air out the back of its engines... it doesnt really care what the ground is doing... could be ice for all it cares...
- prophet0NE0
so the two engines pull enough air around the wings to create 'bernoulli' lift?
- ribit0
The engines push air out the back (see Pratt and Whitney), which makes plane goes forward (see Newton), air moves over wings, shape of wings causes lift (see bernoulli), passengers get to go on holiday (see Expedia)..yay!
you are kidding right?
- skelly_b0
wrong ribit. the wings would be standing still. plane would sit on the runway all day, which means no fruity unbrella drink on the beach for said passengers.
the engines provide thrust to move the plane. the movement, at high enough speed, creates the lift.
- skelly_b0
and to clarify speed would be measured by the distance covered in specific amount of time.
on this conveyor belt the plane would be going 0 mph. Just like my car on the rollers at an emissions testing station is going 0 mph, though the speedometer is tricked by the rpms of the engine.
- dijitaq0
air moving above the wing surface moves faster than the air beneath the wing surface. this cause the air pressure beneath the wing surface to be greater than the air pressure above the wing sufrace. thus producing lift.
if the conveyor belt moves as fast as the airplane in the opposite direction, the plane would be stationary. no air moving around the wing surface. no lift.
- lambsy0
the airplane needs inertia in order to acheive lift.
wankerbez stated a sort of wheel-brake equation; ie. imagine the airplane with engines at full power on the runway with its brakes on, no lift would be acheived.
as soon as the brakes were released, the fuselage would need to reach a forward momentum to gain inertia, then lift would be acheived. the plane simply would not lift immediately after the brakes were released.
imagine running on a treadmill at full speed and jumping off to one side, you would simply jump off to the side. now imagine running down the street at full speed, and jumping to the side, you would have tremendous inertia, and probably eat shit.
- ribit0
OMG. Did anyone study physics here?
"wrong ribit. the wings would be standing still."
Can you explain why the wings would be standing still? With thousands of pounds of thrust pushing the plane forward?
The runway can move backwards as fast as it likes..it just means the plane takes off at its usual airspeed, but with the wheels doing say 20000 RPM rather than the usual 10000 RPM...hardly a problem...