The speed of the treadmill has no bearing on thrust actually. If you set the engine to takeoff setting (torque, manifold pressure, or %), you will take off once you get the proper airspeed regardless of the speed of your wheels. The treadmill is nothing more than a distraction to people watching on the ground and has no bearing on the pilot or the plane.
Note that I am actually a pilot, but if you don't believe me, watch:
The speed of the treadmill has no bearing on thrust actually. If you set the engine to takeoff setting (torque, manifold pressure, or %), you will take off once you get the proper airspeed regardless of the speed of your wheels. The treadmill is nothing more than a distraction to people watching on the ground and has no bearing on the pilot or the plane.
Note that I am actually a pilot, but if you don't believe me, watch:
The speed of the treadmill has no bearing on thrust actually. If you set the engine to takeoff setting (torque, manifold pressure, or %), you will take off once you get the proper airspeed regardless of the speed of your wheels. The treadmill is nothing more than a distraction to people watching on the ground and has no bearing on the pilot or the plane.
Note that I am actually a pilot, but if you don't believe me, watch:
The treadmill does have influence over thrust. If there isn't enough thrust, the friction of the bearings in the wheels will cause the airplane to be slow enough to be ejected off the back of the treadmill. When the treadmill moves, the plane will not stay stationary while the wheels move underneath, even if the jet engines do not drive the wheels. So the jet engines have to thrust to compensate for the speed of the treadmill underneath. Once there is enough thrust compensating for the speed of the treadmill, the plane will take off. You just need a treadmill that can gradually get faster as the jet engines build up thrust. You would also need a lot more thrust to takeoff from a stationary position, rather than increasing lift under the wings from the acceleration provided by the runway space.
I don't think you understand the physics involved in the scenario. Even if the treadmill was moving at 200mph in the oposite direction the plane would need the very minimum of thrust forward to overpower it, assuming it's wheels are not locked by brakes/bad bearings.
You could have the treadmill increase it's speed infinitely but since the plane generates it's forward momentum through thrust of air and not through friction of the wheels to the ground like a car it would take very little effort on the plane's part to take off.
No required quests! And if I decide I want to be an assassin-cartographer-dancer-pastry chef who lives only to stalk and kill interior decorators, then that's who I want to be, even if it takes me four years to max all the skills and everyone else thinks I'm freaking nuts. -Madimorga-
This is one of the single most misunderstood "simple" physics problems currently on the web.
If you don't realize that the treadmill has no effect on the actual takeoff, that's okay. It's not an assualt on your intelligence, most people don't get it.
The speed of the treadmill has no bearing on thrust actually. If you set the engine to takeoff setting (torque, manifold pressure, or %), you will take off once you get the proper airspeed regardless of the speed of your wheels. The treadmill is nothing more than a distraction to people watching on the ground and has no bearing on the pilot or the plane.
Note that I am actually a pilot, but if you don't believe me, watch:
they failed the bust beause the plane had forward movement....the point of the belt was to keep the plane in a stationary place....
just my humble opinion
No, the point of the whole experiment proved that the treadmill alone cannot keep the plane stationary. No matter how fast the treadmill goes, the plane will still fly. Which is why you don't understand the outcome. Even the pilot in that video didn't understand. Not surprising to me though because he was a light sport pilot and not a private or commercial pilot, as light sport does not require as much knowledge in aerodynamics and theory.
The speed of the treadmill has no bearing on thrust actually. If you set the engine to takeoff setting (torque, manifold pressure, or %), you will take off once you get the proper airspeed regardless of the speed of your wheels. The treadmill is nothing more than a distraction to people watching on the ground and has no bearing on the pilot or the plane.
Note that I am actually a pilot, but if you don't believe me, watch:
The treadmill does have influence over thrust. If there isn't enough thrust, the friction of the bearings in the wheels will cause the airplane to be slow enough to be ejected off the back of the treadmill. When the treadmill moves, the plane will not stay stationary while the wheels move underneath, even if the jet engines do not drive the wheels. So the jet engines have to thrust to compensate for the speed of the treadmill underneath. Once there is enough thrust compensating for the speed of the treadmill, the plane will take off. You just need a treadmill that can gradually get faster as the jet engines build up thrust. You would also need a lot more thrust to takeoff from a stationary position, rather than increasing lift under the wings from the acceleration provided by the runway space.
The coeficient of friction on properly greased aircraft axles would be minimal in the overall force equation. You notice that there was no point at which the plane even slowed down, because the treadmill and the friction had no effect on the plane's ability to create airflow over the wing, lifting it off the ground. Just think about it for a minute: The aircraft has to overcome the friction of the bearings and the ground on a normal takeoff on a runway. Once that friction is overcome, any additional (like from a treadmill) spinning by the wheels is inconsequential. Bottom line is that as far as the airplane is concerned, it is just a normal takeoff. All the components concerned with flight; power (thrust), lift, weight, drag, etc are the same regardless of what the wheels are doing as long as the airplane is free to move through the air. Making the ground move faster does not effect anything but the free spinning wheels.
You'll notice that the pilot stated he used the same power settings as a normal takeoff for that day. I believe he stated "there was no difference." Bottom line is that if he needed to "overcome friction" he would have required more power.
The speed of the treadmill has no bearing on thrust actually. If you set the engine to takeoff setting (torque, manifold pressure, or %), you will take off once you get the proper airspeed regardless of the speed of your wheels. The treadmill is nothing more than a distraction to people watching on the ground and has no bearing on the pilot or the plane.
Note that I am actually a pilot, but if you don't believe me, watch:
The treadmill does have influence over thrust. If there isn't enough thrust, the friction of the bearings in the wheels will cause the airplane to be slow enough to be ejected off the back of the treadmill. When the treadmill moves, the plane will not stay stationary while the wheels move underneath, even if the jet engines do not drive the wheels. So the jet engines have to thrust to compensate for the speed of the treadmill underneath. Once there is enough thrust compensating for the speed of the treadmill, the plane will take off. You just need a treadmill that can gradually get faster as the jet engines build up thrust. You would also need a lot more thrust to takeoff from a stationary position, rather than increasing lift under the wings from the acceleration provided by the runway space.
The coeficient of friction on properly greased aircraft axles would be minimal in the overall force equation. You notice that there was no point at which the plane even slowed down, because the treadmill and the friction had no effect on the plane's ability to create airflow over the wing, lifting it off the ground. Just think about it for a minute: The aircraft has to overcome the friction of the bearings and the ground on a normal takeoff on a runway. Once that friction is overcome, any additional (like from a treadmill) spinning by the wheels is inconsequential. Bottom line is that as far as the airplane is concerned, it is just a normal takeoff. All the components concerned with flight; power (thrust), lift, weight, drag, etc are the same regardless of what the wheels are doing as long as the airplane is free to move through the air. Making the ground move faster does not effect anything but the free spinning wheels.
You'll notice that the pilot stated he used the same power settings as a normal takeoff for that day. I believe he stated "there was no difference." Bottom line is that if he needed to "overcome friction" he would have required more power.
You need less thrust to travel the same distance on a teadmill than driving on a runway. Why? There is less friction from wind.
While the friction from the wheels is miminal -- if the engines are not compensating for the speed of the treadmill, then the craft will be ejected off the back of the treadmill. Imagine if the engines weren't activated: the wheels would spin underneath, but not fast enough; so the craft would get ejected. The treadmill wouldn't even need to be going that fast because the friction from the wheels would never allow the aircraft to compensate.
The treadmill causes the craft to be stationary. A craft's stationary position will generate less lift rather than what could be generated from a craft's acceleration down the length of a runway. Even headwinds can reduce the amount of acceleration needed to attain the appropriate amount of lift for takeoff.
The treadmill on mythbusters was not effective (mythbusters sucks; very few of their experiments are conclusive because they do not have budget necessary for testing such phenomena). That treadmill was not designed to keep the craft in place like how exercise and automotive treadmills keep people and automobiles in place.
If the treadmill kept the craft stationary, then the craft would need a significant amount more of thrust to overcome the initial threshold of the prerequisites needed for takeoff.
Dude. I'm a mechanical engineer with significant portions of it in aeronautical engineering, and I'm a pilot. I understand the physics. The question is not "if an airplane were sitting on a treadmill with it's engine off, what would happen?" The question is, "if an airplane were sitting on a treadmill, running it's engine for takeoff, would it takeoff?"
The answer is, yes, and the hard part to understand is: the treadmill has no impact on the final result.
You need less thrust to travel the same distance on a teadmill than driving on a runway. Why? There is less friction from wind.
No. The "friction" caused by wind on the aircraft is called "drag", and that is really only a function of the airflow over the aircraft.
While the friction from the wheels is miminal -- if the engines are not compensating for the speed of the treadmill, then the craft will be ejected off the back of the treadmill. Imagine if the engines weren't activated: the wheels would spin underneath, but not fast enough; so the craft would get ejected. The treadmill wouldn't even need to be going that fast because the friction from the wheels would never allow the aircraft to compensate.
NO. The question is not whether the airplane will be ejected, it is whether the airplane can take off with the thrust of it's own engines. We all know what happens if the airplane were sitting still with no power. But again, that isn't the question. What you fail to realize is that the amount of forward thrust needed to overcome the extra drag in the beginning is minimal and doesn't change the faster the airplane moves forward.
The treadmill causes the craft to be stationary. A craft's stationary position will generate less lift rather than what could be generated from a craft's acceleration down the length of a runway. Even headwinds can reduce the amount of acceleration needed to attain the appropriate amount of lift for takeoff.
The treadmill on mythbusters was not effective (mythbusters sucks; very few of their experiments are conclusive because they do not have budget necessary for testing such phenomena). That treadmill was not designed to keep the craft in place like how exercise and automotive treadmills keep people and automobiles in place.
If the treadmill kept the craft stationary, then the craft would need a significant amount more of thrust to overcome the initial threshold of the prerequisites needed for takeoff.
To the last 3 paragraphs, you are absolutely wrong. The motion of the treadmill cannot hold the aircraft stationary when it sets its power for takeoff. The whole goal is to take off, not to remain stationary. Takeoff power is takeoff power. Unless you have a means to disrupt the airflow over the airfoil (wings), the airplane takes off. Period.
I was going to continue, but being at whit's end, I did a little search for someone who had put more time into this problem than I was willing to. Amazingly there is actually a whole site http://www.airplaneonatreadmill.com/
From which comes a couple quotes:
If the plane moves, it flies. If it doesn't move, it doesn't fly. The real question is, will it move? Again, the answer is unambiguous - if the pilot doesn't try to make the plane stay still, it won't. If he does, it will. This is always, always the part that confuses people
The only reason that a plane or a car moves backwards on a treadmill is that the wheels are somehow partially locked to the axles. In a plane, this is because of minor friction in the bearings. In a car, it's because of the drive train. If you want the car to stay still, you have to turn the drive train at the proper speed. If you want the plane to stay still, you have to overcome the minor bearing friction. And again, since friction does not change with speed, you don't have to exert any more force at higher speeds. If you run the treadmill at 5mph and turn on the plane's engines just slightly, they will provide enough thrust, pushing against the air, to keep the plane still. If you then increase the treadmill speed to 500 mph, you won't need to adjust the throttle on the airplane - it will remain stationary. That's because it's seeing the same frictional force that it was at 5mph. Thus, it doesn't matter how fast the treadmill is moving - if the pilot does not want to remain stationary, then he won't. It only uses the very first bit of power from the engines to keep the plane stationary. As the throttle is increased from that point, it moves forward just as it would on any other runway. It's pushing against the stationary air!
No required quests! And if I decide I want to be an assassin-cartographer-dancer-pastry chef who lives only to stalk and kill interior decorators, then that's who I want to be, even if it takes me four years to max all the skills and everyone else thinks I'm freaking nuts. -Madimorga-
WHat happens when a Rocket, with 2 boosters (one on each end)
was in a vacuum. And the Thrusters on one end was on, for 3mins moving the rocket. Now the first rocket booster stops, and the booster on the opposite end starts up with equal force to the first rocket booster.
Shouldn't the rocket come to a rest now?
if so, what happen to the ENERGY? was it destroyed?
WHat happens when a Rocket, with 2 boosters (one on each end)
was in a vacuum. And the Thrusters on one end was on, for 3mins moving the rocket. Now the first rocket booster stops, and the booster on the opposite end starts up with equal force to the first rocket booster.
Shouldn't the rocket come to a rest now?
if so, what happen to the ENERGY? was it destroyed?
I'm assuming your rocket looks something like this
----->======<------
The center being the rocket body and the dashes representing thrust. With your question and keeping logic in mind if one thruster works and propels the rocket then an equal thruster on the other side would stop it. It would be the same as me putting you on ice skates, pushing you in one direction and then imediately jumping infront of you and pushing back with equal force. All I would be doing is trying to cancel out your momentum with "thrust" from a new direction.
As to your second question, energy can't be destroyed, only changed to some other form of energy. With the rocket what you're doing with the boosters is converting chemical energy into thrust which is a physical push or kinetic energy.
No required quests! And if I decide I want to be an assassin-cartographer-dancer-pastry chef who lives only to stalk and kill interior decorators, then that's who I want to be, even if it takes me four years to max all the skills and everyone else thinks I'm freaking nuts. -Madimorga-
Comments
The speed of the treadmill has no bearing on thrust actually. If you set the engine to takeoff setting (torque, manifold pressure, or %), you will take off once you get the proper airspeed regardless of the speed of your wheels. The treadmill is nothing more than a distraction to people watching on the ground and has no bearing on the pilot or the plane.
Note that I am actually a pilot, but if you don't believe me, watch:
Mythbusters Full Size Airplane on a Conveyor Belt
My mom and dad are twins, do I look alike?
How long is a battleship? True or False?
they failed the bust beause the plane had forward movement....the point of the belt was to keep the plane in a stationary place....
just my humble opinion
The treadmill does have influence over thrust. If there isn't enough thrust, the friction of the bearings in the wheels will cause the airplane to be slow enough to be ejected off the back of the treadmill. When the treadmill moves, the plane will not stay stationary while the wheels move underneath, even if the jet engines do not drive the wheels. So the jet engines have to thrust to compensate for the speed of the treadmill underneath. Once there is enough thrust compensating for the speed of the treadmill, the plane will take off. You just need a treadmill that can gradually get faster as the jet engines build up thrust. You would also need a lot more thrust to takeoff from a stationary position, rather than increasing lift under the wings from the acceleration provided by the runway space.
I don't think you understand the physics involved in the scenario. Even if the treadmill was moving at 200mph in the oposite direction the plane would need the very minimum of thrust forward to overpower it, assuming it's wheels are not locked by brakes/bad bearings.
You could have the treadmill increase it's speed infinitely but since the plane generates it's forward momentum through thrust of air and not through friction of the wheels to the ground like a car it would take very little effort on the plane's part to take off.
No required quests! And if I decide I want to be an assassin-cartographer-dancer-pastry chef who lives only to stalk and kill interior decorators, then that's who I want to be, even if it takes me four years to max all the skills and everyone else thinks I'm freaking nuts. -Madimorga-
This is one of the single most misunderstood "simple" physics problems currently on the web.
If you don't realize that the treadmill has no effect on the actual takeoff, that's okay. It's not an assualt on your intelligence, most people don't get it.
No, the point of the whole experiment proved that the treadmill alone cannot keep the plane stationary. No matter how fast the treadmill goes, the plane will still fly. Which is why you don't understand the outcome. Even the pilot in that video didn't understand. Not surprising to me though because he was a light sport pilot and not a private or commercial pilot, as light sport does not require as much knowledge in aerodynamics and theory.
The coeficient of friction on properly greased aircraft axles would be minimal in the overall force equation. You notice that there was no point at which the plane even slowed down, because the treadmill and the friction had no effect on the plane's ability to create airflow over the wing, lifting it off the ground. Just think about it for a minute: The aircraft has to overcome the friction of the bearings and the ground on a normal takeoff on a runway. Once that friction is overcome, any additional (like from a treadmill) spinning by the wheels is inconsequential. Bottom line is that as far as the airplane is concerned, it is just a normal takeoff. All the components concerned with flight; power (thrust), lift, weight, drag, etc are the same regardless of what the wheels are doing as long as the airplane is free to move through the air. Making the ground move faster does not effect anything but the free spinning wheels.
You'll notice that the pilot stated he used the same power settings as a normal takeoff for that day. I believe he stated "there was no difference." Bottom line is that if he needed to "overcome friction" he would have required more power.
You need less thrust to travel the same distance on a teadmill than driving on a runway. Why? There is less friction from wind.
While the friction from the wheels is miminal -- if the engines are not compensating for the speed of the treadmill, then the craft will be ejected off the back of the treadmill. Imagine if the engines weren't activated: the wheels would spin underneath, but not fast enough; so the craft would get ejected. The treadmill wouldn't even need to be going that fast because the friction from the wheels would never allow the aircraft to compensate.
The treadmill causes the craft to be stationary. A craft's stationary position will generate less lift rather than what could be generated from a craft's acceleration down the length of a runway. Even headwinds can reduce the amount of acceleration needed to attain the appropriate amount of lift for takeoff.
The treadmill on mythbusters was not effective (mythbusters sucks; very few of their experiments are conclusive because they do not have budget necessary for testing such phenomena). That treadmill was not designed to keep the craft in place like how exercise and automotive treadmills keep people and automobiles in place.
If the treadmill kept the craft stationary, then the craft would need a significant amount more of thrust to overcome the initial threshold of the prerequisites needed for takeoff.
Dude. I'm a mechanical engineer with significant portions of it in aeronautical engineering, and I'm a pilot. I understand the physics. The question is not "if an airplane were sitting on a treadmill with it's engine off, what would happen?" The question is, "if an airplane were sitting on a treadmill, running it's engine for takeoff, would it takeoff?"
The answer is, yes, and the hard part to understand is: the treadmill has no impact on the final result.
To the last 3 paragraphs, you are absolutely wrong. The motion of the treadmill cannot hold the aircraft stationary when it sets its power for takeoff. The whole goal is to take off, not to remain stationary. Takeoff power is takeoff power. Unless you have a means to disrupt the airflow over the airfoil (wings), the airplane takes off. Period.
I was going to continue, but being at whit's end, I did a little search for someone who had put more time into this problem than I was willing to. Amazingly there is actually a whole site http://www.airplaneonatreadmill.com/
From which comes a couple quotes:
If the plane moves, it flies. If it doesn't move, it doesn't fly. The real question is, will it move? Again, the answer is unambiguous - if the pilot doesn't try to make the plane stay still, it won't. If he does, it will. This is always, always the part that confuses people
The only reason that a plane or a car moves backwards on a treadmill is that the wheels are somehow partially locked to the axles. In a plane, this is because of minor friction in the bearings. In a car, it's because of the drive train. If you want the car to stay still, you have to turn the drive train at the proper speed. If you want the plane to stay still, you have to overcome the minor bearing friction. And again, since friction does not change with speed, you don't have to exert any more force at higher speeds. If you run the treadmill at 5mph and turn on the plane's engines just slightly, they will provide enough thrust, pushing against the air, to keep the plane still. If you then increase the treadmill speed to 500 mph, you won't need to adjust the throttle on the airplane - it will remain stationary. That's because it's seeing the same frictional force that it was at 5mph. Thus, it doesn't matter how fast the treadmill is moving - if the pilot does not want to remain stationary, then he won't. It only uses the very first bit of power from the engines to keep the plane stationary. As the throttle is increased from that point, it moves forward just as it would on any other runway. It's pushing against the stationary air!
Kinda what I said ^
No required quests! And if I decide I want to be an assassin-cartographer-dancer-pastry chef who lives only to stalk and kill interior decorators, then that's who I want to be, even if it takes me four years to max all the skills and everyone else thinks I'm freaking nuts. -Madimorga-
I have a question:
WHat happens when a Rocket, with 2 boosters (one on each end)
was in a vacuum. And the Thrusters on one end was on, for 3mins moving the rocket. Now the first rocket booster stops, and the booster on the opposite end starts up with equal force to the first rocket booster.
Shouldn't the rocket come to a rest now?
if so, what happen to the ENERGY? was it destroyed?
Philosophy of MMO Game Design
I'm assuming your rocket looks something like this
----->======<------
The center being the rocket body and the dashes representing thrust. With your question and keeping logic in mind if one thruster works and propels the rocket then an equal thruster on the other side would stop it. It would be the same as me putting you on ice skates, pushing you in one direction and then imediately jumping infront of you and pushing back with equal force. All I would be doing is trying to cancel out your momentum with "thrust" from a new direction.
As to your second question, energy can't be destroyed, only changed to some other form of energy. With the rocket what you're doing with the boosters is converting chemical energy into thrust which is a physical push or kinetic energy.
No required quests! And if I decide I want to be an assassin-cartographer-dancer-pastry chef who lives only to stalk and kill interior decorators, then that's who I want to be, even if it takes me four years to max all the skills and everyone else thinks I'm freaking nuts. -Madimorga-