prop planes need lift to take off. lift is made by changes in air pressure. a plane that is sitting still will not create a lower air pressure above its wings, because the wings will not be moving any air.
A "jet" would be able to take off from a "belt" but not a propellar plane
This ad is not displayed to registered and logged-in members. Register your free account today and become a member on Dodge Forums!
Vehicle: 96 Ram daily driver/88 Power Ram that is Lugnuts arch nemisis
Posts: 899
RE: finally they will put an end to this
A jet will just move foward, it`s the airflow over the top edge of the wing that generates lift. The curved surface of the top edge of the wing creates low air pressure, while the flat bottom keeps the air pressure the same causing upward force to be applied to the wing. If that wasn`t true, then why would you bother with putting a wing on your car? All that is is a reversed plane wing.
I'm seeing two different interpretations of the question, which is the difference between landspeed (speed relative to treadmill) and airspeed (speed relative to a fixed point on the surroundings, say a building)....
A.) If you think of a plane on a treadmill the length of a runway and light the engines and turn on the treadmill. Then yes the plane will take off, the landing gear are only hooked to brakes, no kind of driving motor, the plane will overcome the conveyor and thrust forward (the landing gear will be turning at twice the speed of the plane, which may cause some other issues..durability, perhaps??) but eventually the engines on the plane will overcome the treadmill and theplane will take off (twice the amount of thrust as regularly needed). In this case land speed (speed relative to treadmill) will be twice that of airspeed but the correct airspeed would eventually be achieved and the plane will take off.
B.)If you are assuming the intent of this theoretical conveyor is to keep the plane stationary to a fixed point outside the conveyor (landspeed = takeoff speed, airspeed = 0), then the plane would be generating the amount of thrust needed for take off but have zero airspeed, meaning no pressure differential over the wings and no lift force, thus no take-off.
It will be interesting to see how they model it...
__________________
-Bob T-
-------------------------------
"Alright brain, you don't like me and I don't like you, so let's just get through this so I can go back to killing you with beer."
-Homer J. Simpson-
There would be no lift on the palnes wings, think about it, Have you ever road a bike on a treadmill? there is speed but no air flow. The only way that this would work is if the air around the plane was moving at the same speed as the treadmill causing lift. I doubt this will work.
yes, a bike on a treadmill, you will go nowhere. since the wheels are what move the bike. the air plane. the propeller moves the plane, and the wheels are just free rolling.
so how do you think a plane thats on water takes off if it has no wheels
Yes I get that however regardless the plane has to get up to speed in order to take off to create lift, if the plane is stationary, like the way the mythbusters are going to be doing it, the plane will justsit there. The way they are testing it is that if thetreadmill is going the same speed as the planes take off speedthe plane will lift off without the plane its selfgetting up to speed in other words just the treadmill is moving and the plane is remaining in the same spot and is just fighting the drag.
Now if the planewas actuallytaking off andwhile thetreadmill is also going at the take off speed the plane would be able to take off, all it would have to do is match the drag of the treadmill and increase the speed because all the wheels free spinningare there to help it get up to speed. I'm not dooubting that it isn't paossible, BUT I doubt that it will take off the way they are testing the "myth".
And the plane will have that airflow. Free spinning wheels + thrust (power for movement) provided by the propellor = conveyor doesn't really make a difference.
This is the correct principle. Forward motion of an aircraft is not governed by the ground. But they will likely mess it up somehow.
__________________ As a DF moderator My opinion is only my own and does not represent the DF community, it's staff, or affiliates. I moderate solely based upon guidelines and not in regards to my own personal beliefs. Rear Wiper Club Member #2
Quote:
Originally Posted by PappiDread6
Hello My Name is Pappi Dread and I have an addiction, Male DF Members
Yes I get that however regardless the plane has to get up to speed in order to take off to create lift, if the plane is stationary, like the way the mythbusters are going to be doing it, the plane will justsit there. The way they are testing it is that if thetreadmill is going the same speed as the planes take off speedthe plane will lift off without the plane its selfgetting up to speed in other words just the treadmill is moving and the plane is remaining in the same spot and is just fighting the drag.
Now if the planewas actuallytaking off andwhile thetreadmill is also going at the take off speed the plane would be able to take off, all it would have to do is match the drag of the treadmill and increase the speed because all the wheels free spinningare there to help it get up to speed. I'm not dooubting that it isn't paossible, BUT I doubt that it will take off the way they are testing the "myth".
Even with that said there is a bit of confusion here...
Will the plane be under its own power in these tests?
If the plane is going to be under power enough to cancel out the "drag", as you state,(which is actually just the friction of the wheel bearing since the wheels are free flowing) then there will be little power needed to accomplish this. And if this is the case then the plane will not take off.
now in the other scenario...
As many mentioned airflow is needed for the wings to create lift. This is simple physics and can be explained by Newton’s First Law of Motion.
The confusion is that people are not realizing that the plane is going to move forward on a conveyor belt a create lift. The wheels are free spinning. The brakes are not on.The conveyor belt is no different than a sea plane taking off in a river the opposite way of the river's flow.
The question to the non-believers in this scenario is why wouldn't the plane move forward?
RE: finally they will put an end to this
