“Since the belt measures the speed of the plane (assume ground speed) and applies the exact same velocity but in the opposite the direction, the plane WILL NOT MOVE.”
ohh my goodness…i can see this is going to be tougher for you youngings than I thought…
1=the plane is 100% isoloated from the conveyor due to the FACT it does not move through space from wheel LOCOMOTION… it uses friggen thrust to propel it forward…
if its wheels are going 1 million miles an hour the other way (if they could ) it has no bearing on its forward thrust created by the jet engines…
wheels are on the ground… conveyors are on the ground… planes are NOT
now this would be TOTALLY diffrent if instead of a plane it was a CAR…the car could never get off the conveyor no matter how hard it tried…since ITS form of locomotion is its WHEELS…the conveyor would compensate…
however a plane is NOT a car…nor is a rocket…
lets say a rocket is on this conveyor…and you lanch it? your telling me that cause the conveyor is moving 1000mph or whatever below it , it has any effect on the rocket?..
the rocket would fly off just like normal…same as the plane…however in the planes case…its little wheels would be moving more quickly than normal…due to the fact the conveyor was trying to comepensate for the planes increasing forward motion in relation to the conveyers fixed position on the ground…
engine placement is a factor of the planes center of gravity more than anything…and the fact that jet turbine exhaust will melt the aircraft
and if you look at some old fighters like the ones from korea that used a single nose air inlet you could say some of the engine is actually infront of the main wings…
all nose propeller planes have thier engines in front of the wings
the plane will not take of because of the fact planes dont fly soley due to thrust. they need lift to take off. lift is caused by air moving over the wings. the forward motion is canceld out by the converor belt, there is no air passing over the wings and therefore no lift is created.
I am assuming this conveyor belt is like a runway strip…that instead of pavement is one long conveyor say 2km long…
is that what we are assuming?
or are we assuming that this “conveyor” is in fact all encompassing, and that all the ground in the planet is this conveyor? and that when this conveyor moves…all the air around it is moving as well with the conveyor?
either way…unless this conveyor through its movement creates a opposite wind speed in relation to the plane it does not matter…
NOW…if this conveyor along with moving the ground is moving the AIR around the plane as well… then thats another story…
if its moving the air in a opposite direction to the thrust…then the plane will never take off…since the air speed over the wings will be zero and no lift can occur…
firstly, a plane is basically a car with wings. as soon as the plane and belt make contact, they become part of the same system under speculation. thrust INDIRECTLY creates lift. thrust is a force which propels the plane forward, creating an airflow over the wings, hence creating lift. when that airflow increases velocity, lift will increase.
“wheels are on the ground… conveyors are on the ground… planes are NOT” please stop talking. are the wheels not attached to the plane?? therefore the plane is on the ground! the plane is taking off on the ground, not in midair.
Let’s pretend there’s no belt for a moment. The thrust created by the engine (a force-- F=ma) accelerates a plane forward along the ground increasing its velocity until the airflow reaches an airspeed which creates enough lift equal and greater than the weight of the plan.
lets place a plane and a car floating in the vacuum of space …and see which one can move forward…(provided you have oxygen on board to power the engines
the wheels spinning in the air…or the plane moving forward from thrust…
if a plane is flying by thrust alone (e.g. fighter planes) then it is flying my thrust alone, meaning not enough lift is being generated to support the weight of the aircraft. taking off from the ground requires lift on the wings, not thrust alone. if there is no lift on the wings and the engine is just thrusting the airplane forward (assuming no conveyor belt) the plane will just go forward in the direction dictated by the thrust. where did you go to school man?
i see what you’re trying to get at but the types of locomotion are simliar. the energy is just applied to different methods of creating ‘thrust’. a car sends energy to the crankshaft which in turns the driveshaft spinning the wheels. a plane applies energy to the crankshaft which is applied to the propeller. a jet engine just provides a large amount of force in one direction (oh guess what, land speed record cars use jet engines!) so my statement is still valid.
Okay, one louis110, where do you go? Just out of curiosity.
Two: ADAM, we’ll get into this on boxing day if you come visit me and Andrew in the shop
Three: Everyone is making lots of assumptions here.
First assumption is that there is no relative wind. If there is no relative wind on the aircraft’s wings, it will not take off. The conveyor spinning backwards will prevent ADDITIONAL relative wind to be created, by the aircraft’s acceleration. However, what if this conveyor runway is located in an area where there’s 300km/h winds blowing lets say south, and the airplane is facing north. The airplane will be able to take off due to relative wind, assuming a 300km/h wind will make enough lift (usually true). Furthermore if something as nearly impossible as this runway was created, what is to say that there also doesn’t exist a giant fan that can generate this kind of wind?
Second assumption is the aircraft’s configuration. Is this a VTOL aircraft or no? 99% of aircraft won’t be able to take off under such scenarios, especially transports. No transport has enough thrust to make it take off without a massive amount of lift. When I was doing take off simulations for certain transports, the lift force was on a magnitude of 100-1000 times that of the thrust force.
Haha, no reason to get all defensive, I’m also Aero at Ryerson. Maybe we’ll run into eachother sometime this coming semester, or I’ll TA one of your courses if I stay for a masters.
not sure what school has to do with anything…or what your major in school is…
however I graduated York U , in 94’, and took a few aeronautical courses there for fun when i was there…
I think you guys will find that I am correct… you guys are just getting mired down in the thought that the wheels have some magical effect…
ok…lets try this… the wheels spin freely…correct (they do pending a slight drag from the baeraings in them and the rubber meeting the conveyor) they can move back and forth either way depending on which direction and speed the conveyor is moving… ok we can all agree on that right?
now… we know that every action has an equal and oposite reaction…correct…
lets say the wheels will suck up maybe 500hp of drag due to bearings and the tires hitting the conveyor…
lets say the jet has about ohh 20,000 hp…at full throttle… regardless of the drag of the wheels which is just for fun…500hp…it still has in excess 19,500hp in excess thrust available…
and guess what… when its is being applied…that over and above power of what the wheels are sucking up… HAS to go somewhere… and in this case…its thrust in the form of forward movement of the plane…
the plane will still take off once it reaches its take off speed that i normally needs…if its a head wind then it will need less speed in relation to the earth…if its a tail wind then it will need more speed in relation to the earth…
the conveyor has no bearing on this thrust powered vehicle…
like I said… CARS are a 100% different story…and a car could NOT escape the confines of this conveyor…
“The conveyor spinning backwards will prevent ADDITIONAL relative wind to be created, by the aircraft’s acceleration”
if that was true…rockets could not fly in the vacum of space…
we are talking about…
THRUST…
every action has an equal and opposite reaction… its as simple as that…
if we had a stationary marker off the conveyer…the plane would move away from this stationary marker as it increased its engine thrust…simple as that… only difference would be the additional drag from the wheels due to the conveyor trying to compensate for the increased spped of the plane…
i swear to God you’re gonna give me a heart attack. stop saying that the wheels have nothing to do with the situation. ok yea the wheels are independent of the thrust being outputted by the engines, but the wheels allow a plane to move along the ground as a result of its thrust.
“we know that every action has an equal and oposite reaction” the velocity created by the thrust is the action, the opposite velocity of the belt is the reaction!! How hard is that to comprehend?!
and please use the term “friction” instead of “drag” to avoid confusion.
you’re so convinced that the amount of thrust put out by an engine will result in movement and lift as a result of that. so under your understanding when engineers do fixed engine tests (where a jet engine is fixed into a stationary position) as soon as they increase the thrust output, the engine is going to go shooting out of the room??
) it has no bearing on its forward thrust created by the jet engines…