Let's have an argument - Argh it keeps recurring!
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Elmlea wrote:Consider me facepalming. If it’s a trick on words, fair enough; but lift generated is directly proportional to the square of the wing’s velocity relative to the air around it, so that’s all that matters; how fast is the wing moving through the air. If the conveyor’s like a treadmill so it isn’t moving relative to the air (as in rolling forwards) it won’t fly. If you had a 200mph wind screaming down a runway, then a jet could face into that, and fly quite happily.
All I can add is a mention of the tyres' coefficient of friction, where any generated lift would have an effect on their abrasive friction with the treadmill.
Likewise, with zero lift the treadmill spinning the tyres would increase their grip through kinetic heat exchange (as far as I understand molecular science). A white (or just cold) conveyor belt should theoretically reduce this adhesive grip slightly. The proper answer's Harrier, though, innit.
But I don't know about plane physics, so I pity those fools.
regmcfly wrote:What if Jesus was flying the plane
He could mock his dad on the bus. -
Does this work any better?
If a plane were to be put on a conveyor belt that moves in the opposite direction to the plane, and is capable of moving at the same speed the plane can, can the plane take off? -
Presumably the same speed would include the thrust from the engines, so no. -
Diluted Dante wrote:Does this work any better? If a plane were to be put on a conveyor belt that moves in the opposite direction to the plane, and is capable of moving at the same speed the plane can, can the plane take off?
Yeah that's better. I think there's still a bit of an issue with "capable of moving at the same speed the plane can" though, maybe the best way to define it would be to do a "plane moves x mph with x acceleration in order to take off and the conveyor does x in the opposite direction". I think my wording of the thing being controlled in a feedback loop invoked a potential paradox. -
Diluted Dante wrote:Does this work any better?
If a plane were to be put on a conveyor belt that moves in the opposite direction to the plane, and is capable of moving at the same speed the plane can, can the plane take off?
Yes in theory the plane can take off eventually because the friction between the wheels and the belt is still not 100%.
The belt influence is its speed divided by the effectiveness of the friction on the wheels while the engine's influence is no different than if it was on a runway.
Edit: sorry you meant as a question framing. But yeah that works.
Edit edit: it would still assume the wheels could free move.
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How much force does it take to lift the wheels off the ground on a light aircraft? That's a more interesting question for me.
And with that system in place (were it weightless), what would the new takeoff speed be? I guess we're getting into microlight territory there. -
Just in case anyone is genuinely pissy at me for this I just want to reiterate that it was all in good faith, it's not intended to be a gotcha. My sort of smugness on the first page is because I could see that people were going to go on similar journey to mine, and that the eventual realisation is ultimately quite enlightening and interesting. It's also just a fun physics experiment to picture in your head.
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Nothing to see here"Plus he wore shorts like a total cunt" - Bob
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I got pissy but not at you. Really though it has filled my evening and made me think so its not all bad.
There are certainly worse of this type of thing out there. Facebook is full of them. This at least does have some form of answer. -
ALL FLIGHTS ARE CANCELLED.Come with g if you want to live... -
I have a treadmill upstairs. I might see if it can make me fly. -
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Depends on the amount of airflow underneath the plane's wings. If the airflow's sufficient the plane will lift from the ground.
Considering the plane doesn't actually move relative to the ground and through the air, there's no actual airflow underneath the wings. Thus, there will be no lift.
Ergo, that shit won't fly.Steam: Ruffnekk
Windows Live: mr of unlocking
Fightcade2: mrofunlocking -
A lot of explanations start with "planes aren't cars" and while I know what they are getting at if we are going into detail like tyre friction most cars would also gain distance over the belt because of tyre tread patterns.
Wouldn't take off though, the loss of friction would slow them down. -
monkey wrote:What if the conveyor belt had wings? What then eh?
Try a wind tunnel and see magic happen.Steam: Ruffnekk
Windows Live: mr of unlocking
Fightcade2: mrofunlocking -
Escape wrote:How much force does it take to lift the wheels off the ground on a light aircraft? That's a more interesting question for me. And with that system in place (were it weightless), what would the new takeoff speed be? I guess we're getting into microlight territory there.
Having played a bunch of Flight Simulator I've really fallen in love with the Shock Ultra, that thing is almost VTOL -
It has some special wing arrangements that maximise the utility of the prop wash, I think. If I had the money I would go move somewhere beautful and just swoop around in my plane all day -
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LivDiv wrote:most cars would also gain distance over the belt because of tyre tread patterns.
The difference between concrete and bitmac for car drifting's quite interesting. The grippiest surface is one that's bedded-in enough to be jagged, but not so much that the rocks are starting to come loose (loose gravel's the least grippy of all*). Whereas concrete's lower friction grip doesn't cancel out its adhesive grip, so breakaways on slicks can be very sudden.
Concrete's also prone to cracking in winter under heavy load.
*Motocross tracks are regularly (or should be) graded to remove the nastier stuff:
A (maybe) surprising thing about riding offroad in the wet is that there's often more grip on grass than well-ridden mud. Enduro riders look for untouched lines.
GurtTractor wrote:If I had the money I would go move somewhere beautful and just swoop around in my plane all day
Some ex-RAF airfields are surprisingly cheap to use. Y'know, once you've got a plane. -
Aye all's well then. I did do some research and tried my best to make the question not shitty, and messed up a bit because of those pesky details. I love that though, asking the question is just as unintuitive as answering it.
The plane takes off and flies. -
I need a piss, but that’s the extent of my pissyness.
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Just read the various explnations.
That's a whole lotta assumptions. I still think I've got it right going by the op.Steam: Ruffnekk
Windows Live: mr of unlocking
Fightcade2: mrofunlocking -
hunk wrote:Depends on the amount of airflow underneath the plane's wings. If the airflow's sufficient the plane will lift from the ground. Considering the plane doesn't actually move relative to the ground and through the air, there's no actual airflow underneath the wings. Thus, there will be no lift. Ergo, that shit won't fly.
It's not stated that the plane will not move, the point is that the plane will move, because the thrust from the propeller/jet is acting on the air and not through the wheels. The wheels on a plane are just a way of keeping the plane off of the ground with a low amount of friction. -
No pissiness here. Got another 30 years before that starts (hopefully). -
I still need a piss.
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No it isn't.PSN : time_on_my_hands
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The plane’s engines pull it forwards through the air, regardless of what its wheels and the conveyor belt are doing.
The conveyor is a distraction. Ignore it. The plane moves forward, accelerates and takes off just as it normally would.
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