Plane on a conveyor belt
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AFAIK it depends. I am assuming treadmill is movig at the same speed as the engines would be propelling the aircraft forward, thus making the aircraft basically stationary on the treadmill with the wheels spinning. If the airplane has strong enough engines to pull the entire weight into the air without the aid of the lift created by the wings then it will fly, but the engines would have to be pointed at an angle to go 'up'. in this scenerio the aircraft would also be able to lift itself into the air from a standing stop without a treadmill, like a VTOL. in the case of a normal passenger aircraft, where the engines themselves are not enough to pull the aircraft into the air, the aircraft needs to be moving forward at a certain rate of speed (say 150mph) for the wings to create enough lift to get it off the ground. In that case, if the treadmill is keeping the aircraft from moving forward and creating lift, the aircraft will not take off. if you did the same thing in a wind tunnel however, with enough wind to create enough lift under the wings, the aircraft would fly. also if the treadmill were as long or longer than a runway and the engines of the aircraft were somehow strong enough to pull the aircraft forward at takeoff speed against the treadmill (so on a 50mph treadmill, 200mph assuming a 150mph takeoff speed) but not enough to lift the aircraft without the aid of lift created by the wings, it would fly once it reached takeoff speed. just the way i think about it.
as i understand it, most aircraft stay in the air via lift via thrust. the engines are not strong enough to pull a gigantic jetliner into the air from a standing stop. instead, the aircraft has huge wings. the engines move the wings forward at a high enough rate of speed for the wings themselves to create enough lift to get the aircraft into the air. if the aircraft slows down too much, the wings cannot create enough lift and the aircraft stalls and drops until moving again at a high enough rate of speed to create enough lift to get flying again.
as i understand, some of you think an aircraft flies by the thrust of the engines. you would need thrust equal to the weight of the aircraft to get off the ground. can you imagine the amount of power it would take to lift a 747 straight up off the ground? holy shit! you also wouldn't need wings, you could manuver the aircraft with thrust vectoring or varying the angle of attack of the blades like a helicopter.
a few examples:
the harrier jet. the engines produce enough THRUST to lift the aircraft straight up off the ground.
the osprey: the engines spin the blades, which are basically wings, at a high enough rate of speed to create enough LIFT to get the osprey off the ground. In forward flight, the blades are still angled slightly up to retain altitude. the wings are there to keep the blades from wacking into each other, and to facilitate manuverability. A helicopter works in the same way. except without the wings.
amirite?
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here is an example of an aircraft light enough with an engine powerfull enough to cause it to fly without lift. basically it could be thought of as a helicopter with the control surfaces on the aircraft instead of angleing the blades.
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JohnW;199198 wrote:
AFAIK it depends. I am assuming treadmill is movig at the same speed as the engines would be propelling the aircraft forward, thus making the aircraft basically stationary on the treadmill with the wheels spinning.And this is where you are wrong. Sorry. The treadmill can spin at 10,000mph, and assuming the tires don't blow/bearings don't fail, the plane will still move forward on the treadmill relative to the stationary ground. Once the plane is moving forward at a fast enough speed there WILL BE AIR FLOWING OVER THE WINGS and the plane will take off.
If you ignore physics and somehow create a treadmill that will be able to hold a plane stationary on it, the plane will not take off. But, if you get to ignore physics for your theory, I get to ignore gravity.
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Or think about it this way...I can take a toy car and roll it across to the belt of a belt sander w/ no problem when the sander is off. Turn the sander on and I can still roll the toy car forward on the belt sander. The force of the belt sander is > the force that I can exert on the toy car, yet I am still able to move it across its moving surface. In the treadmill vs plane scenario, the treadmill likely has less force than the jet/prop/whatever of the aircraft and therefore will not inhibit the forward motion of the plane at all. If forward motion is not prevented, the plane will move forward forcing air over the wings and when proper speed is attained for takeoff, the plane will lift off. Every time.
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ok yes it will take of no matter what the speed of the conveyor is going.
conveyor 50mph, then the plane wheels go 50mph when it is standing still. so when it is going say 200mph to generate enough lift to take so the wheels are going 200mph. now if you ad the speed of the conveyor going the opposite direction the wheel will be travling 250mph. and the plane will still take of no matter what the speed of the wheels and it is not the wheel that drive the plane it is the thrust from the jet engines.
now if a ged having high school drop out can answer this in a semi cohearent manner. how the fuck do you ppl not get how a plane works??????
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Notice that the setup never tells you what speed of the plane to use. I take that as an open door for both theoretical and practical approaches.
Obviously if you use the plane's airspeed or ground speed the plane will take off.Now if you use the plane's rolling speed, which is relative to the belt, then the plane can't theoretically take-off, just based off the matched speeds. Practically this can never occur unless the plane is at rest. -
Used;199214 wrote:
Notice that the setup never tells you what speed of the plane to use. I take that as an open door for both theoretical and practical approaches.
Obviously if you use the plane's airspeed or ground speed the plane will take off.Now if you use the plane's rolling speed, which is relative to the belt, then the plane can't theoretically take-off, just based off the matched speeds. Practically this can never occur unless the plane is at rest.Actually, it takes off either way...the point on the conveyor and the plane can & will both move if both are in motion. If you measure its speed relative to treadmill it still doesn't prevent the plane from moving as the plane and the conveyor can move in opposite directions of each other. The only way to stop the plane from taking off is to ignore physics and the way a plane operates.
As for the speed of the plane, well the question states that the belt matches the speed of the plane, and since the belt has absolutely no real affect on the planes ability to accelerate, I think it is safe to say it will accelerate to the point in which it can take off.
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oh...and just to end the controversy..... SPOILER ALERT
watch the video on the bottom of this page (pay attention to what the pilot says):
http://dsc.discovery.com/fansites/mythbusters/mythbusters.html
then read the article here: (link was requiring log in..just copy/pasted the whole article now)
Mythbusters' still happily blowing stuff up
By Susan Young STAFF WRITERArticle Launched: 10/30/2007 03:02:45 AM PDT
Really, does it get any cooler than testing out the classic cartoon joke involving a trail of gunpowder and a big explosion? Not for
Mythbuster'' Adam Savage, who deems this blow-up one of his favorites. You can't swing a comatose Sylvester without hitting a rerun ofMythbusters'' on Discovery Channel, but finding fresh episodes can be a challenge since the network rolls out a few at a time throughout the year. The good news is that fans can look forward to seven new episodes beginning Wednesday.
We lit a line of gunpowder to a keg leading to an explosion,'' Savage says of the segment airing Wednesday.It was one of the more minor explosions we've done onMythbusters,' but more deeply satisfying from a cartoon perspective.'' The series has gone beyond merely being a hit cable series. It's a cultural icon is based in co-host Jamie Hyneman's special effects studio on San Francisco, with most of the myths busted or confirmed right here in the East Bay from Alameda to Dublin. The No. 1 question the 'busters get asked is if they will ever run out of myths? ``We say we'll run out of ideas when people ever stop believing stupid things,'' Savage says. ``We just finished one that has confounded us our entire careers.'' The episode, which airs in December, finds Savage and Hyneman tackling a question baffling everyone from bloggers to pilots: If a plane is traveling at takeoff speed on a conveyor belt, and that conveyor belt is matching the speed in reverse, can the plane take off? ``We put the plane on a quarter-mile conveyor belt and tested it out,'' says Savage about the experiment using a pilot and his Ultralight plane. ``I won't tell you what the outcome was, but the pilot and his entire flight club got it wrong.'' Savage often describes ``Mythbusters'' as ```Jackass' meets Mr. Wizard.'' And when you think about wacky stunts done on the show, Tory Belleci's name invariably pops up. On the Nov. 14 ``Supersized'' two-hour episode, Belleci will attempt to wakeboard from the back of a cruise ship. Not, he says, the craziest thing he's had to do on the show. In fact, this season also has him testing out whether your pants can catch fire while being dragged behind a horse. Other seasons has seen him sticking his tongue onto a frozen pole and getting in a pen with a bull to see if the animal would indeed charge him because he was wearing a red outfit. ``When I was in the arena with the bull or with the crocodile, everything inside my body was saying don't do it, but you know you have to do it,'' Belleci says. ``I feel like I spent my whole life preparing for this job. I loved playing with fire and at 19 I was almost arrested for making a pipe bomb. Everything I used to get in trouble for I'm now doing as my job.'' Both Belleci and Grant Imahara came to ``Mythbusters'' after working at Industrial Light and Magic. ``People always ask why I would leave ILM, and it's becauseMythbusters' sounded like fun. Working on movies and TV is a blast, and ILM has the most talented people in the world,'' Imahara, who lives in Oakland, says.But on `Mythbusters' I've been able to go places I would never have access to otherwise.'' Not only that, but Imahara says he believesMythbusters'' just may be responsible for making nerds cool.
Look at `Heroes' and `Numb3rs' and all these new shows coming out now and we were on the forefront,'' Imahara says.The nerd is the protagonist, the hero. I worked at ILM the same time Masi Oka was there. Who would have thought that two Asian-American nerds from ILM would be on hit shows?'' -
This post is deleted!
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http://www.startribune.com/entertainment/tv/11503366.html
hopefully that link will work
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ok im confused and undecided. a few questions
so if the conveyor is moving 100mph, then would the speed of the planes wheels match that of the conveyor...but in the opposite direction, and cancel eachother out? just like walking on a treadmill, you dont move unless you are moving slower or faster than the speen of the tread mill.
ok next. now wouldnt the turbine have to be placed in front of the wing to create some sort of lift on the wing? because if i remember right from 6th grade science....you need air above the wing moving faster than the air speed below to reduce pressure and create the "lighter than air" effect of lift on the wing that makes it take off. because there isnt any air speed outside to make any lift on the wings if the plane is at a stand still.
and how in the hell would a heavy ass plane just jump in the air from a stand still??? im so confused...
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