- My Forums
- Tiger Rant
- LSU Recruiting
- SEC Rant
- Saints Talk
- Pelicans Talk
- More Sports Board
- Fantasy Sports
- Golf Board
- Soccer Board
- O-T Lounge
- Tech Board
- Home/Garden Board
- Outdoor Board
- Health/Fitness Board
- Movie/TV Board
- Book Board
- Music Board
- Political Talk
- Money Talk
- Fark Board
- Gaming Board
- Travel Board
- Food/Drink Board
- Ticket Exchange
- TD Help Board
Customize My Forums- View All Forums
- Show Left Links
- Topic Sort Options
- Trending Topics
- Recent Topics
- Active Topics
Started By
Message
re: Can this 747 take off?
Posted on 4/10/24 at 11:09 pm to highcotton2
Posted on 4/10/24 at 11:09 pm to highcotton2
quote:
If you held a hot wheels car on a treadmill do you think you could move the car forward with your hand? No matter how fast the treadmill was going it would take very little force to move the car forward with just your hand.
Except that this magical treadmill would then go faster at a perfectly equal speed to you moving the cars wheels, and you could never actually move it forward.
The basic premise is that the wheels are used for initial momentum forward which creates lift. If the wheels don’t allow the plane to move forward, it would be similar to a plane trying to takeoff with a 150mph head wind that magically got faster the faster the plane was going. There would be no lift either.
It needs lift to fly, without lift there’s no flying no matter what sort of thrust you can create. Making the premise anymore complicated due to real life physics than that simple idea defeats the purpose as none of this could be real to begin with.
This post was edited on 4/10/24 at 11:11 pm
1
Posted on 4/10/24 at 11:47 pm to Street Hawk
No. The thrust of the engines will definitely move the plane forward. The conveyor will prevent the wheels from gaining any ground by spinning. Therefore the wheels will skid on the conveyor. The thrust of the engines would not be enough to overcome the friction of the skidding wheels. ETA: The engines will overcome the friction but not enough to get to takeoff speed.
The fallacy is that there is no such thing as an instantaneous feedback loop that could speed the conveyor up at the same rate as the wheels. The scenario is impossible. The only thing that would cause the conveyor to start moving is wheel rotation which necessitates forward motion.
ETA: My certainty of being correct is 50%.
The fallacy is that there is no such thing as an instantaneous feedback loop that could speed the conveyor up at the same rate as the wheels. The scenario is impossible. The only thing that would cause the conveyor to start moving is wheel rotation which necessitates forward motion.
ETA: My certainty of being correct is 50%.
This post was edited on 4/13/24 at 3:19 am
Posted on 4/11/24 at 12:22 am to LNCHBOX
quote:
I even gave you a very simple example to illustrate why the plane would move. You don't want to hear it, so I believe I'm done here.
Your scenario violated the conditions set forth in the OP. Your example was useless.
Posted on 4/11/24 at 12:36 am to Hateradedrink
quote:
Imagine a plane going down a runway with rubber sleds instead of tires. There would be a lot of burning smoke, but the plane would move forward and take off.
The plane would move forward, but I doubt it would achieve the 200 knots (or whatever is necessary) to take off.
Posted on 4/11/24 at 12:42 am to baldona
quote:
The basic premise is that the wheels are used for initial momentum forward which creates lift.
But that is the whole problem here.
They aren’t. The wheels are irrelevant to the motion of the plane, because it is pushing against the air, not the ground. It doesn’t transition from pushing the ground to pushing the air. The only force imparted by the wheel is friction in the bearing, and it’s nowhere near enough to counter or even retard thrust. You using the phrase “initial momentum” as if it changes later implies you don’t understand this.
Let’s try a different track:
A rocket on sleds on a slick conveyor belt. You really think it stays put?
What’s hilarious is that myth busters actually did this with an actual plane, but the deniers still had a recursive logic of “well the plane took off so obviously they didn’t do it right.”
Almost flat earth levels of denial.
ETA: damn, someone else tried the sled angle.
This post was edited on 4/11/24 at 12:53 am
Posted on 4/11/24 at 12:47 am to DavidTheGnome
quote:
No because the airflow around the wings remains the same thus not creating lift
Houston, we have a problem... no wheels.
Posted on 4/11/24 at 6:46 am to WWII Collector
quote:
Houston, we have a problem... no wheels.
I came back to post this, but it's the same thing....
This post was edited on 4/11/24 at 7:05 am
Posted on 4/11/24 at 6:46 am to WWII Collector
I know most of y'all are relatively intelligent people. The levels of stupidity ITT are therefore even more amazing!
Posted on 4/11/24 at 7:36 am to Volvagia
quote:
They aren’t. The wheels are irrelevant to the motion of the plane, because it is pushing against the air, not the ground. It doesn’t transition from pushing the ground to pushing the air. The only force imparted by the wheel is friction in the bearing, and it’s nowhere near enough to counter or even retard thrust. You using the phrase “initial momentum” as if it changes later implies you don’t understand this.
In a real scenario, correct. In a real scenario there’s a ton of variables not taken into context with the simple problem.
This isn’t real, end of story.
In the scenario in the op, the point is that the plane has 0 forward momentum because the conveyor is keeping the air speed 0. The conveyor is moving the airplane’s body the same as the wheels, there’s 0 forward momentum.
If you want to make a bunch of real life shite up, that’s irrelevant. We don’t know the real variables. You are making a bunch of egregious engineering variables up to satisfy yourself.
Posted on 4/11/24 at 7:44 am to Street Hawk
If the belt is going in the opposite direction the same speed as the wheels wouldn’t the forward speed be 0? If so, I think there wouldn’t be enough air to lift the plane off the ground.
Posted on 4/11/24 at 7:51 am to carhartt
It couldnt take off anyway, if it moved forward it would just fall off the conveyor/treadmill and crash. Look how short that thing is.
This post was edited on 4/11/24 at 8:01 am
Posted on 4/11/24 at 7:57 am to baldona
quote:
In the scenario in the op, the point is that the plane has 0 forward momentum because the conveyor is keeping the air speed 0. The conveyor is moving the airplane’s body the same as the wheels, there’s 0 forward momentum.
What forces are the wheels exerting on the plane to affect the momentum?
quote:
If you want to make a bunch of real life shite up, that’s irrelevant. We don’t know the real variables. You are making a bunch of egregious engineering variables up to satisfy yourself.
I don't think you know what making up means. One of y'all is making things up, and it's not who you think.
Posted on 4/11/24 at 8:37 am to LNCHBOX
quote:
What forces are the wheels exerting on the plane to affect the momentum?
Where is the planes mass?
Posted on 4/11/24 at 8:41 am to baldona
quote:quote:
What forces are the wheels exerting on the plane to affect the momentum?
Where is the planes mass?
Which axis is that force exerted?
Posted on 4/11/24 at 8:48 am to Street Hawk
As long as there is air flowing over the wing, the plane is generating lift.
The question is, does the plane actually move forward in this scenario?
Theory 1 - The conveyor moves fast enough to counteract any forward movement by the aircraft, it remains stationary, and this does not move nor fly
Theory 2 - The wheels move however the aircraft still has forward momentum, generates lift, and flies
My interpretation is that the power from an aircraft is coming from the engines and not the wheels. The conveyor would not act like a "brake" and that it prevents the wheels from moving at all. The plane would begin to accelerate down the conveyor despite the opposite force, and the plane would take off.
The question is, does the plane actually move forward in this scenario?
Theory 1 - The conveyor moves fast enough to counteract any forward movement by the aircraft, it remains stationary, and this does not move nor fly
Theory 2 - The wheels move however the aircraft still has forward momentum, generates lift, and flies
My interpretation is that the power from an aircraft is coming from the engines and not the wheels. The conveyor would not act like a "brake" and that it prevents the wheels from moving at all. The plane would begin to accelerate down the conveyor despite the opposite force, and the plane would take off.
Posted on 4/11/24 at 8:50 am to Street Hawk
Well, since the wheels aren't what make a plane fly, I'm going to go ahead and say no.
Posted on 4/11/24 at 8:55 am to Volvagia
quote:
What’s hilarious is that myth busters actually did this with an actual plane, but the deniers still had a recursive logic of “well the plane took off so obviously they didn’t do it right.”
The problem with the Mythbusters exercise is the truck was incapable of going to infinity speed.
The question is not a practical real world question, which is what causes the argument and makes it funny. As the wheels keep increasing speed, the treadmill is doing the same with them driving both to infinity very quickly. Something is going to break, wheel bearings or treadmill.
If the wheels go first, does that mean the treadmill goes back to 0.
This post was edited on 4/11/24 at 8:56 am
Posted on 4/11/24 at 8:57 am to Dam Guide
quote:
The problem with the Mythbusters exercise is the truck was incapable of going infinity speed.
It doesn't need to go infinity speed. It only needed to keep up with the speed of the plane to bust the myth.
quote:
The question is not a practical real world question, which is what causes the argument and makes it funny. As the wheels keep increasing speed, the treadmill is doing the same with them driving both to infinity very quickly. Something is going to break, wheel bearings or treadmill.
But the wheels aren't what makes the plane move. The question doesn't say to ignore how planes work. If you want to look at the question literally, the plane is going to fall off the conveyor belt. But it will move. If we're also staying in fantasy land with this magic conveyor belt defies reality, you also have to consider that the bearings/hub/axles etc are also magic and won't break.
This post was edited on 4/11/24 at 9:02 am
Posted on 4/11/24 at 9:00 am to Volvagia
You can also expound on this and say that if you pull the toy car forward by the string it would not require more effort than if the treadmill were off. This is how the thrust of the planes engines work. The wheels are only there for the plan to sit on.
Posted on 4/11/24 at 9:02 am to Volvagia
quote:
The answer is yes. An airplane isn’t like a car. It doesn’t move by pushing against the ground. It therefore moves within the frame of reference of the air. The only thing that will happen here is the wheels would spin twice as fast, and if assembled by Boeing, fall off.
Please stay in your social sciences lane. Physics and engineering are NOT in your wheelhouse
Page 6 of 26
Popular
Back to top
Follow TigerDroppings for LSU Football News