A plane on a runway, how smart is r3vlimited?

[Axxe]

Justin, all that matters is that we know we are fighting the good fight :D

[chucko]

What the hell crack are you smoking? It never said infinity, as far as the problem is concerned, the belt and plane could be only doing 1mph each. Of course inifinity will never be reached, the belt and plane only can travel as fast as the plane can move forward with the added drag of the wheels spinning faster. It will move forward, want that same amount of drag, or roughly, on a normal runway? attach more wheels to the existing landing gear, there you go. The plane will still accelerate, just minutely slower. It will get to pretty damn close to the maximum air speed a plane can get on a traditional runway, and certainly up to enough air speed that it will have enough to take flight.

None of your business what crack I'm smoking, just admit that your logic is flawed. In order for the plane to move forward from a dead stop, the wheels will have to be moving faster than the conveyor belt, this problem states that the belt speed is equal and oppisite to the plane speed. In this case the wheel speed = the plane speed, you can not separate the two unless you apply an initial force to the plane before the belt starts moving. You can't do that in this problem.

[Justin B]

Your explanation is flawed my friend. You are saying that at some point the plane will be moving at 100mph and the conveyor will be moving at 50mph, this can NOT happen based on the problem posed. The problem states the conveyor belt will be moving at exactly the same speed as the plane. You can not create a scenario where the plane and the belt are moving at different speeds.

Please, look at te picture. The plane is continuing at an airspeed of 50mph. the ONLY THING, ONLY ONLY ONLY, not the plane, not the conveyor belt, not the passengers in the plane, nothing else is doing 100mph besides the wheels.

THe only reason the wheels are doing 100mph once they hit the conveyor belt is because the conveyor belt is doing 50mph backwards + the 50mph airspeed of the plane = 100mph wheel speed. NOTHING ELSE. Tell me how that is flawed then go back to middle school.

It is not flawed, you're just thinking too hard to convince yourself you're correct. I understand how that works, and trust me its hard to see the other way, but its correct.

Thank you Axxe :D

[Axxe]

Your explanation is flawed my friend. You are saying that at some point the plane will be moving at 100mph and the conveyor will be moving at 50mph, this can NOT happen based on the problem posed. The problem states the conveyor belt will be moving at exactly the same speed as the plane. You can not create a scenario where the plane and the belt are moving at different speeds.

He was using it to try to convince the stubborn dumbasses. It really is quite frustrating when the problem is so simple but all the "smart" people get so trapped up in th wrong answer that by the time their stubborn minds realize that they are indeed wrong, they look retarded.

Seriously guys, the plane will take off as if the conveyor isn't even there. The conveyer has no real measurable affect, the wheel bearings do not create enough resistance in comparison to air resistance to be of any concern to this problem.

[Justin B]

This is NOT a real situation. If the wheels are moving at infinity to the right and the belt is moving at infinity to the left, no jet can make the wheels move faster than infinity. The plane doesn't move period.

What the hell crack are you smoking? It never said infinity, as far as the problem is concerned, the belt and plane could be only doing 1mph each. Of course inifinity will never be reached, the belt and plane only can travel as fast as the plane can move forward with the added drag of the wheels spinning faster. It will move forward, want that same amount of drag, or roughly, on a normal runway? attach more wheels to the existing landing gear, there you go. The plane will still accelerate, just minutely slower. It will get to pretty damn close to the maximum air speed a plane can get on a traditional runway, and certainly up to enough air speed that it will have enough to take flight.

[chucko]

Ok guys, take off your thinking caps, they're obviously defective.

Yes, theres gravity. It creates drag on the wheels, NO, the plane is not glued to the ground. wtf? It is called gravity, and it creates friction on the wheels, nothing more, aside from requiring lift to take off. It however gets that air speed after it overcomes the friction of the wheels, as it always would whenever any airplane takes off from a standard runway.

With this riddle it just so happens to have more friction at the wheels, because the wheels are spinning faster backwards, and all of you see this to be causing the plane to stay stationary. However, that is reading too far into, or not enough into, the question. I cant quite decide. It will not hold the plane stationary.

The reason I have mentioned about frictionless wheels is for sake of explanation of the mechanics of the plane vs the conveyor belt and airspeed (the relative speed the airplane is going compared to everything else in its surroundings not including the conveyor belt). Obviously you all are taking my frictionless wheels into more serious consideration that I had anticipated. It was all semantics.

Here's one more example. You have a RC model airplane okay? We all know they have a great power/weight ratio as compared to manned aircraft but the same principles apply. Do not turn this RC plane around on me and tell me its not realistic, its how the mythbusters would do it, and its essentially exactly the same as the bigger planes but on a smaller more powerful scale.

You have a conveyor belt runway, you speed up the conveyor belt to spin at whatever speed you anticipate the airplane to take off at after it leaves your hands when sat on the ground at, lets say half throttle. Fire up the plane and set it on the conveyor belt and it will take off like any other RC plane on a normal runway, it just happens to be that the wheels are forced to spin faster than they have to for the airspeed that the plane is seeing.

One more time, and an illustration I made up real quick, the airplane must be actually physically moving for the conveyor belt to be moving backwards. In my little picture the plane is moving at 50mph airspeed on the ground, and the conveyor belt it taxi's onto is going at 50mph backwards. By your logic the plane should stop dead in its tracks, but it will not. It will continue at 50mph. It may slow down for a split second and regain speed from the shock of the wheels grabbing the belt going backwards and being required to spin up to 100mph, another 50mph to match the airspeed of the plane as well as the conveyor belt underneath working against the wheel bearings. They freely spin as far as anything is concerned though, and the plane continues forward.


Think of it like this, PLEASE. That is as close to an instantaneous example I can give. After all, it is the same exact thing as a conveyor belt instantaneously starting to roll backwards at the same rate the plane accelerates from a stop. The wheels and conveyor belt will not hold the plane in one spot, as that is not fulfilling the requirements of the question/riddle in the first place, and secondly the order of events that will happen (all at once of course) would be while the plane accelerates forwards, and the belt backwards which you believe will cancel out any motion, all thats happening is the wheels are accelerating twice as fast as both, because it is both speeds combined at any point in time.

Post count +1. I think you'll just keep disagreeing just so we can postcount +1 forever, but can you modify post counts, that way we can end this now. Admit your defeat :) Give me the title "It Will Fly" at least :) LOL

Your explanation is flawed my friend. You are saying that at some point the plane will be moving at 100mph and the conveyor will be moving at 50mph, this can NOT happen based on the problem posed. The problem states the conveyor belt will be moving at exactly the same speed as the plane. You can not create a scenario where the plane and the belt are moving at different speeds.

[Justin B]

OOh, beacuse you guys are all thinking about voting, to let you know, I voted No too. Funny huh? I'm serous, I was thinking the same exact way you did till I finally figured out that the power plant in an airplane will hopefully always be powerful enough to pull the plane along at a certain airspeed creating drag AND able to spin its little wheels at twice the RPM they should be....

AGain, I voted no, and now I'm voting against myself. Its all good yo. :P

[Justin B]

Yes but I think you missed my point. What I'm trying to say is that in order to solve this problem the amount of thrust required to increase the speed of the plane on the conveyer must first be determined by the amount of power needed to overcome friction & drag created by the wheels.

That resistance, while it IS there, it is very little.

Ok.. now everyone listen the fuck up.. are we arguing theory or real world probability?

Because in theory it's easy you find the amount of thrust needed to obtain take off speed and overcome the drag created by the wheels and the fucker still flys.

In reality there is a high probability that the plane's wheels will malfunction before take off but I cannot prove it without calculating the proper coefficients into the equation.

If Mythbusters were to take this on my money would be that the plane's tires either blow out or the wheel bearing fry before thrust overtakes wheels friction for take off.

wow, getting a little feisty now huh? I was pretty heated at some points but I managed to keep it cool. Calm down buddy, this is just a friendly discussion while people disagree with eachother. We just try to convince eachother till we're all dead! How about that, fun huh

I know I'm having fun.

Yes, there would be some serious equations. The question is not in reality though, so any assumptions are acceptable. If you really want to get into it you'll have to calculate EVERYTHING including surrounding wind speed, its not worth it. If the wheels on the plane are free rolling theyre free rolling, of coures it will have SOME resistance but so very little that it wont make enough resistance that a jet or any other piddly air-pushing thing on an ultralight even wont be able to overcome the resistance of the wheels rolling twice as fast as they need to reach and maintain the required airspeed to take off.

Thank you. :)

[Justin B]

Ok guys, take off your thinking caps, they're obviously defective.

Yes, theres gravity. It creates drag on the wheels, NO, the plane is not glued to the ground. wtf? It is called gravity, and it creates friction on the wheels, nothing more, aside from requiring lift to take off. It however gets that air speed after it overcomes the friction of the wheels, as it always would whenever any airplane takes off from a standard runway.

With this riddle it just so happens to have more friction at the wheels, because the wheels are spinning faster backwards, and all of you see this to be causing the plane to stay stationary. However, that is reading too far into, or not enough into, the question. I cant quite decide. It will not hold the plane stationary.

The reason I have mentioned about frictionless wheels is for sake of explanation of the mechanics of the plane vs the conveyor belt and airspeed (the relative speed the airplane is going compared to everything else in its surroundings not including the conveyor belt). Obviously you all are taking my frictionless wheels into more serious consideration that I had anticipated. It was all semantics.

Here's one more example. You have a RC model airplane okay? We all know they have a great power/weight ratio as compared to manned aircraft but the same principles apply. Do not turn this RC plane around on me and tell me its not realistic, its how the mythbusters would do it, and its essentially exactly the same as the bigger planes but on a smaller more powerful scale.

You have a conveyor belt runway, you speed up the conveyor belt to spin at whatever speed you anticipate the airplane to take off at after it leaves your hands when sat on the ground at, lets say half throttle. Fire up the plane and set it on the conveyor belt and it will take off like any other RC plane on a normal runway, it just happens to be that the wheels are forced to spin faster than they have to for the airspeed that the plane is seeing.

One more time, and an illustration I made up real quick, the airplane must be actually physically moving for the conveyor belt to be moving backwards. In my little picture the plane is moving at 50mph airspeed on the ground, and the conveyor belt it taxi's onto is going at 50mph backwards. By your logic the plane should stop dead in its tracks, but it will not. It will continue at 50mph. It may slow down for a split second and regain speed from the shock of the wheels grabbing the belt going backwards and being required to spin up to 100mph, another 50mph to match the airspeed of the plane as well as the conveyor belt underneath working against the wheel bearings. They freely spin as far as anything is concerned though, and the plane continues forward.


Think of it like this, PLEASE. That is as close to an instantaneous example I can give. After all, it is the same exact thing as a conveyor belt instantaneously starting to roll backwards at the same rate the plane accelerates from a stop. The wheels and conveyor belt will not hold the plane in one spot, as that is not fulfilling the requirements of the question/riddle in the first place, and secondly the order of events that will happen (all at once of course) would be while the plane accelerates forwards, and the belt backwards which you believe will cancel out any motion, all thats happening is the wheels are accelerating twice as fast as both, because it is both speeds combined at any point in time.

Post count +1. I think you'll just keep disagreeing just so we can postcount +1 forever, but can you modify post counts, that way we can end this now. Admit your defeat :) Give me the title "It Will Fly" at least :) LOL

[chucko]

lol argue whatever you want. justin made a good point via aim, jets would probably be powerful enough to overcome the traction. this though is outside of the scope of the question. i was arguing more idealistic conditions where everything works as it should.

i conclude tonight that it can go either way, depending upon whether or not this is real physics with friction or just an idealistic problem. if anyone wants to debate that, please do, ill catch up tomorrow

This is NOT a real situation. If the wheels are moving at infinity to the right and the belt is moving at infinity to the left, no jet can make the wheels move faster than infinity. The plane doesn't move period.

[chucko]

be sure to vote :pimp:

I did vote No. Ofcourse the plane will take off if the plane is facing the same direction as the direction the conveyor belt is moving.Your initial problem does not say which direction the plane is facing. Just says the plane can only move in one direction. Imagine if the plane is facing the same direction as the conveyor belt is moving, but the wheels are moving in reverse, then you apply the brakes, the plane will be thrust forward to a speed sufficient to obtain lift.

[boom-monkey]

This is what you guys get for arguing with high schoolers/marketing majors.

Plane will take off, end of story.

[BENdashdash]

lol argue whatever you want. justin made a good point via aim, jets would probably be powerful enough to overcome the traction. this though is outside of the scope of the question. i was arguing more idealistic conditions where everything works as it should.

i conclude tonight that it can go either way, depending upon whether or not this is real physics with friction or just an idealistic problem. if anyone wants to debate that, please do, ill catch up tomorrow

[RobertK]

Ritalinkid -

Your diagrams show the conveyor belt cancelling out all of the thrust of the airplane by matching the resistance of the wheels at a certain speed.

Yes but I think you missed my point. What I'm trying to say is that in order to solve this problem the amount of thrust required to increase the speed of the plane on the conveyer must first be determined by the amount of power needed to overcome friction & drag created by the wheels.

The question clearly states that the conveyor belt is matching the speed of the plane. If the plane is stopped relative to the surrounding ground, the conveyor belt should not be moving either. I see where you're coming from but its wrong. The conveyor belt in your diagram should be moving at half its speed so that the forward motion and the belt are both moving at the same rate, and the same rate of acceleration etc.

Again.. not the point I'm trying to make to begin with.

The point is that on a normal runway, lets say for the plane to fly it needs to get up to a certian speed we'll call S, and to do that, it will need the thrust T to over come not only the rolling resistance of the wheels, but the airflow and drag over the whole plane. Now, move it onto our special runway with a moving track, all it needs is a radar gun on one side attatched to a speed control for the track to roll only at the speed the plane is actually moving forward. That is the question. Will it fly? Yes, of course, to get up to S, it will need a little more than T, but less than 2T as it wont be pushing twice the air, just overcoming the slight bit of more rolling resistance from the runway at twice the speed the plane is actually traveling through the air/ surrounding ground.

That's what I've been thinking but I cannot prove it without the correct coefficients needed to calculate the thrust needed to overcome the friction at the wheels.

The plane will take flight, but using your model of the rolling resistance, which really isnt included in the question, all it needs is a little more thrust to overcome the wheels spinning underneath, which should be entirely doable. The worst that could happen would be that the runway would have to be a little bit longer for the plane to get up to speed.

Ok.. now everyone listen the fuck up.. are we arguing theory or real world probability?

Because in theory it's easy you find the amount of thrust needed to obtain take off speed and overcome the drag created by the wheels and the fucker still flys.

In reality there is a high probability that the plane's wheels will malfunction before take off but I cannot prove it without calculating the proper coefficients into the equation.

If Mythbusters were to take this on my money would be that the plane's tires either blow out or the wheel bearing fry before thrust overtakes wheels friction for take off.

[BENdashdash]

The plane will NOT take off if it is facing opposite the direction the conveyor belt is moving. The plane WILL take off if it is facing the direction the conveyor belt is moving.

Assuming the plane is facing opposite the direction of the conveyor belt, and assuming the conveyor belt is capable of moving at an infinite speed, the wheels of the plane will NEVER move the plane forward relative to some initial position (inertial frame). The only way a plane can take off is with forward momentum relative to a fixed position and atmosphere (air). Remember, a plane needs no jets to take off, just needs to be moving faster than the air around it. Conveyor belt moves at an infinite speed to the left, the wheels of the plane move at an infinite speed to the right. The air around the plane does not move so the plane does not take off (jets have no impact on this problem).

That is the answer to your question folks!

be sure to vote :pimp: