No, I just want to say if we ignore all these little things, then I can start working. I mean, a boat would not float downriver at the same speed as the river itself, due to air friction.
OK[RDH]Warlord wrote:
No, I just want to say if we ignore all these little things, then I can start working. I mean, a boat would not float downriver at the same speed as the river itself, due to air friction.
Ok, well, if the river is going 100 MPH downriver, and we need to take off going upriver at 30 MPH, then again it can take off. Because of the skids, the full force of the 100 MPH downriver force is not applied to the whole plane, that can use a little forward thrust to stand still. Add a little more thrust, and it can take off.
The numbers:
Let's assume that the skids on a plane have a friction ratio of 2:1, in that a 100 MPH downriver force feels like a 50 MPH force. The plane revs up to it's max speed of 80 MPH. since 50 of that is taken by the river, then the other 30 enables it to take off. And once it takes off, it suddenly jumps ahead fast because there's no longer any backwards 50 MPH force.
The numbers:
Let's assume that the skids on a plane have a friction ratio of 2:1, in that a 100 MPH downriver force feels like a 50 MPH force. The plane revs up to it's max speed of 80 MPH. since 50 of that is taken by the river, then the other 30 enables it to take off. And once it takes off, it suddenly jumps ahead fast because there's no longer any backwards 50 MPH force.
Totally right, ecxept for the bit I hi-lighted. Headwind HELPS a plane take off because it increases the speed of the airflow over the wing, therefore the plane can take off at a LOWER groundspeed. Tailwind has the opposite effect.GotMex? wrote:
Krauser98 is entirely right here. Planes don't depend on tire traction like a car does to move forward. Instead, they use those massive jet engines to compress high volumes of air and then burn the jet fuel, expelling a good amount of air backwards thus creating thrust. The only reason we have wheels on jets is to give them a low-friction contact with the ground. Also, I saw someone say something about friction not allowing you to take off, but the friction created by the wheels/treadmill would be very small compared to the amount of thrust one jet engine is able to produce. Maybe it would be a little harder to take off, but so is having head wind against the plane.Krauser98 wrote:
Yes! Yes it would! You're all wrong!!! The treadmill would have no effect on the plane because it is being pushed / pulled by a jet / propeller! It's not a car! The wheels are not what makes it go, thus the plane would go right off the end of the treadmill with little to no difference. (Until the wings hit the handlebars on the treadmill that is.) As normal, the air would be flowing under the wings, because the plane would be moving forward. If the plane were powered by it's wheels it would only be able to fly short distances and would be more of a jumping car than an airplane. My answer is a solid Yes, the plane would still take off!
Additionally, the wheels would be spinning at about twice the speed of the airplane if such conveyor belt was built.
But anyway, good question, and good answer.
Go to an airport with a bag of marbles. Find the convayer belt walkway thingy and use your arms (jet engines) to propel the marble (jet) down the belt.viper313 wrote:
But the treadmill is matching the planes speed. No matter how fast the planes thrust is the treadmill compensates for this. Thats the key. If the treadmill was at a fixed speed it would take off. And even with bearings, there is always friction!
The marble will continue to roll until it loses thrust from your arm (fuel runs out) in which case it will roll back to you on the convayer.
Give the marble wings, roll it hard enough, and it WILL take off, at which point the convayer will have no effect on it.
If a pilot were to fire up his jet's engines he'd roll forward. If he then cuts the engines out, he doesn't stop just because the ground isn't moving.
etc etc
Why should we assume this?[RDH]Warlord wrote:
Ok, well, if the river is going 100 MPH downriver, and we need to take off going upriver at 30 MPH, then again it can take off. Because of the skids, the full force of the 100 MPH downriver force is not applied to the whole plane, that can use a little forward thrust to stand still. Add a little more thrust, and it can take off.
The numbers:
Let's assume that the skids on a plane have a friction ratio of 2:1, in that a 100 MPH downriver force feels like a 50 MPH force. The plane revs up to it's max speed of 80 MPH. since 50 of that is taken by the river, then the other 30 enables it to take off. And once it takes off, it suddenly jumps ahead fast because there's no longer any backwards 50 MPH force.
Well I think I have the Answer...
While I say no the plane won't fly, I do see the point that others have said about the jet engines pushing on the air not the ground...
So whats the right answer....
Both.
The question never states if the treadmill is matching the ground speed of the plane or the air speed of the plane. If it matches the ground speed, the tires would just spin twice as fast as the plane is going but if it is matching the airspeed (the speed coming out of the engines) than no the plane would not move at all.
While I say no the plane won't fly, I do see the point that others have said about the jet engines pushing on the air not the ground...
So whats the right answer....
Both.
The question never states if the treadmill is matching the ground speed of the plane or the air speed of the plane. If it matches the ground speed, the tires would just spin twice as fast as the plane is going but if it is matching the airspeed (the speed coming out of the engines) than no the plane would not move at all.
I'm surprised you are such a hawk being such a pot fanatic. Weed makes me dovish.
This is awesome. I asked my dad about it at lunch in the MGM and he says it would not take off, but he couldn't give me a satisfactory reason as to why not. I think tonight after we go see BMG I'm going to have a better discussion about it. Also, when I fly back from Vegas, I'm asking the pilot on my flight what he thinks. I still think the plane would fly, except that when it got to the end of the treadmill the wings would smash into the handle bar and cause the plane to crash. Please refer to my MS Paint diagram below for more.
Edit: I added the quote stuff.
So are you saying rolling wheels don't have static friction? Check out what Wikipedia has to say about Rolling Friction. If you're saying the thrust from the engines is counteracted by the treadmill pushing the wheels back because of the kinetic friction between the wheels and ball bearings, then the wheels would be moving so fast the tires would melt and come off the actuall wheel causing the plane to crash anyways.djphetal wrote:
So, for all of the energy the jets provide, that energy is displaced upon the movement of the wheels NOT HAVING STATIC FRICTION... because the treadmill is moving, thus, so are the wheels.
Edit: I added the quote stuff.
Last edited by Krauser98 (2006-12-26 16:36:32)
Okay greenie...
It Wont!
yeah it would fly, because it doesnt use the wheels to create velocity. the wheels would be spinning freely 2x normal speed, but the plane would still take off at the same speed.
doing so risks accleration of the charge of karma whoring, so I didn't.TPM-J45P3R- wrote:
|edit| - whoever +1 me didnt leave yer name!
From here ( 1000 ) on out, I no longer leave my name on anything but reply/return karmas.
You just hinted at my next thread subject ( reward .[RDH]Warlord wrote:
No, I just want to say if we ignore all these little things, then I can start working. I mean, a boat would not float downriver at the same speed as the river itself, due to air friction.
I dont get it,
Well, anything LESS than 2:1, and it will definately take off.JG1567JG wrote:
Why should we assume this?
But any plane unable to get beyong 80 MPH, and any river running as fast as 100 MPH, is pretty wierd, but we have to assume something.
You see, the point is that objects on a surface, like a ground plane on tarmac or a seaplane on a river, are designed to have little friction with the surface below it. With water, you get 100% of the backwards push when the object is underwater. If it's ON the water, then it must be much less. I bet that you could hold on to a plane (if barely) that is floating on a river just by standing on the bank with a rope attached to it. So if you can counter a 100 MPH river flow, then an airplane engine should be able to easily.
What, you mean one about how long it takes a guy to drive a boat upstream X miles when it is flowing X MPH and he can only go X MPH? Not as deep as this question was.ATG wrote:
You just hinted at my next thread subject ( reward .
YES - the aircraft WOULD take off.
conturary to what everyone's saying, the aircraft WOULD take off.
This is because it is not the wheel's that are providing THRUST.
What would actually happen is the wheels would be spinning at TWICE the rpm they would be under normal conditions, as the aircraft moves...
so yes... the aircraft would move, and thus create lift, thus take off
conturary to what everyone's saying, the aircraft WOULD take off.
This is because it is not the wheel's that are providing THRUST.
What would actually happen is the wheels would be spinning at TWICE the rpm they would be under normal conditions, as the aircraft moves...
so yes... the aircraft would move, and thus create lift, thus take off
would not take off, lift is created by wind hitting the Aerofoil if the plane was not moving through its surroundings there would be insufficient air hitting it creating no lift
It depends. Answer these questions.
1. How many doors does it have?
2. How many birds are flying overhead?
3. Has there been a recent terrorist attack in the area?
4. Are there any dogs in the area?
5. Has the person that flies the plane normally eaten a banana in the past month?
6. What's in the plane?
7. What's the square root of pi?
8. Are you a virgin?
9. If you are still reading this, good for you!
1. How many doors does it have?
2. How many birds are flying overhead?
3. Has there been a recent terrorist attack in the area?
4. Are there any dogs in the area?
5. Has the person that flies the plane normally eaten a banana in the past month?
6. What's in the plane?
7. What's the square root of pi?
8. Are you a virgin?
9. If you are still reading this, good for you!
Bubble gum?ATG wrote:
Lets just say, anybody here familiar with my and some of the posts I've made featuring pix of mi casa knows I don't buy dime bags of swag.D6717C wrote:
Interesting question. It wouldn't take off, because there is no airflow over the wings. The wings need air moving over them at a high enough speed to create lift, or nothing would happen. Would look pretty funny though. You just buy a dime sack of weed or what?
http://i17.tinypic.com/4d467h1.jpg
Junk Drawer is a place of whimsy. The thought crossed my mind as an absurdity and I was curious what people would have to say about it.
ps, I have been a unapologetic pot smoker for longer than most of you posting have been alive. I don't advocate it to anyone, but I make no excuses for enjoying it.
Nice try there pal.lukeiamnotyourfather wrote:
It depends. Answer these questions.
1. How many doors does it have?
2. How many birds are flying overhead?
3. Has there been a recent terrorist attack in the area?
4. Are there any dogs in the area?
5. Has the person that flies the plane normally eaten a banana in the past month?
6. What's in the plane?
7. What's the square root of pi?
8. Are you a virgin?
9. If you are still reading this, good for you!
Sure, thanks!Fredrik wrote:
Bubble gum?ATG wrote:
Lets just say, anybody here familiar with my and some of the posts I've made featuring pix of mi casa knows I don't buy dime bags of swag.D6717C wrote:
Interesting question. It wouldn't take off, because there is no airflow over the wings. The wings need air moving over them at a high enough speed to create lift, or nothing would happen. Would look pretty funny though. You just buy a dime sack of weed or what?
http://i17.tinypic.com/4d467h1.jpg
Junk Drawer is a place of whimsy. The thought crossed my mind as an absurdity and I was curious what people would have to say about it.
ps, I have been a unapologetic pot smoker for longer than most of you posting have been alive. I don't advocate it to anyone, but I make no excuses for enjoying it.
- JdeFalconr
- Lex Luthor, King of Australia
- +72|6531|Sammamish, WA
All the propellors do is push the plane forward by forcing air backward (equal and opposite reaction...). They do not push air backwards over the wings in great enough quantities to generate lift.Krauser98 wrote:
Yes! Yes it would! You're all wrong!!! The treadmill would have no effect on the plane because it is being pushed / pulled by a jet / propeller! It's not a car! The wheels are not what makes it go, thus the plane would go right off the end of the treadmill with little to no difference. (Until the wings hit the handlebars on the treadmill that is.) As normal, the air would be flowing under the wings, because the plane would be moving forward. If the plane were powered by it's wheels it would only be able to fly short distances and would be more of a jumping car than an airplane. My answer is a solid Yes, the plane would still take off!
Now what does create lift (as was stated previously in this thread) is air moving over the wings at high speed and over enough of the surface area of the wings. In other words the plane must have a forward velocity if air is to move over its wings. On a treadmill that moves backwards at a speed equal to the plane's force forward the plane would therefore have no net forward velocity. Without a high forward velocity a plane's wings cannot generate lift and therefore the plane will never take off on a treadmill.
if you still disagree consider this: when you're on a treadmill is there wind in your face? What about when you start running fast on a treadmill? No, of course not! The same would be true for a plane, and thus not enough lift can be generated for a plane to gain flight.
People like you COMPLETELY miss the entire point of this. The thrust from the engines would MOVE THE PLANE FORWARD, CREATING LIFT.JdeFalconr wrote:
All the propellors do is push the plane forward by forcing air backward (equal and opposite reaction...). They do not push air backwards over the wings in great enough quantities to generate lift.Krauser98 wrote:
Yes! Yes it would! You're all wrong!!! The treadmill would have no effect on the plane because it is being pushed / pulled by a jet / propeller! It's not a car! The wheels are not what makes it go, thus the plane would go right off the end of the treadmill with little to no difference. (Until the wings hit the handlebars on the treadmill that is.) As normal, the air would be flowing under the wings, because the plane would be moving forward. If the plane were powered by it's wheels it would only be able to fly short distances and would be more of a jumping car than an airplane. My answer is a solid Yes, the plane would still take off!
Now what does create lift (as was stated previously in this thread) is air moving over the wings at high speed and over enough of the surface area of the wings. In other words the plane must have a forward velocity if air is to move over its wings. On a treadmill that moves backwards at a speed equal to the plane's force forward the plane would therefore have no net forward velocity. Without a high forward velocity a plane's wings cannot generate lift and therefore the plane will never take off on a treadmill.
if you still disagree consider this: when you're on a treadmill is there wind in your face? What about when you start running fast on a treadmill? No, of course not! The same would be true for a plane, and thus not enough lift can be generated for a plane to gain flight.
There's the original question. Now, I'm not really on anyone's side, but here's my argument.ATG wrote:
A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).
Will the plane be able to take off?
Aircraft need wind flowing over the wings to provide lift, correct? Now take a normal aircraft, sitting on the runway. If it were to take off, it would have to create some sort of thrust to get it down the runway, namely the engines. You would still need some groundspeed to provide enough airspeed to provide lift. An aircraft requires some groundspeed to take off, because.. well.. it just doesn't jump into the sky and fly like a Harrier or a heli.
When you place a plane onto said treadmill, which apparently compensates for ground speed in the opposite direction (refer to original post) you would still need to build groundspeed to take off, if the conditions were perfect and there was no wind. Thus, it would not take off. Jet engines provide thrust to move an aircraft along the ground to generate lift, therefore said treadmill would prevent it from taking off.
That's my 2 cents on it.
(Someone really needs to send this to mythbusters and record te episode if it comes on)
Not bad for a 15 year old huh?
Yeah except that the thrust produced by the engines would move the plane forward. The wheels do not provide the power, they just turn, so if the treadmill is turning at an equal and opposite speed of the wheels, the wheels would be spinning twice as fast but the engine thrust would still propel the plane forward.chaosdragon001 wrote:
There's the original question. Now, I'm not really on anyone's side, but here's my argument.ATG wrote:
A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).
Will the plane be able to take off?
Aircraft need wind flowing over the wings to provide lift, correct? Now take a normal aircraft, sitting on the runway. If it were to take off, it would have to create some sort of thrust to get it down the runway, namely the engines. You would still need some groundspeed to provide enough airspeed to provide lift. An aircraft requires some groundspeed to take off, because.. well.. it just doesn't jump into the sky and fly like a Harrier or a heli.
When you place a plane onto said treadmill, which apparently compensates for ground speed in the opposite direction (refer to original post) you would still need to build groundspeed to take off, if the conditions were perfect and there was no wind. Thus, it would not take off. Jet engines provide thrust to move an aircraft along the ground to generate lift, therefore said treadmill would prevent it from taking off.
That's my 2 cents on it.
(Someone really needs to send this to mythbusters and record te episode if it comes on)
Not bad for a 15 year old huh?
Last edited by bobby177 (2006-12-26 22:00:06)
Yes, move the plane forward on the ground. Now isn't the treadmill moving it backward? Thus negating any movement made.
No, the treadmill moves backwards, spinning the wheels backwards, but the plane itself remains stationary except for a slight movement backwards because of friction. Now you turn on the thrusters, and that provides enough force to overcome the slight backwards movement and provide speed forward, creating LIFT!chaosdragon001 wrote:
Yes, move the plane forward on the ground. Now isn't the treadmill moving it backward? Thus negating any movement made.