This weekend I had the pleasure of seeing inside a fully working preserved lighthouse dating from 1880.
http://www.photosales.co.nz/details.php?gid=61&pid=2803
The engineering and construction of everything is fantastic - the glass lenses are amazing - but what I think is relevant to Bessler is the mechanism for rotating the lenses. It is the centerpiece of the whole light house - and upstairs it is a large heavy flywheel, mounted horizontally on some large precision taper roller bearings. This is powered by a heavy weight that takes about 2 hours to fall has to be raised via a hand crank. A lighthouse keeper's job must have been very physically demanding - constantly winding up that weight.
I watched this huge flywheel start up from stationary - and it accelerates very quickly. In this day of electric motors and stuff, it's refreshing to see the clean power of gravity at work (even if this isn't in any way self sustaining).
It's easy to forget the impact that a real Bessler wheel would have had in that era, since we are surrounded with electric motors that we take for granted.
This gives me an idea for considering ...
Akaroa Lighthouse 1880
Moderator: scott
Akaroa Lighthouse 1880
Anything not related to elephants is irrelephant.
re: Akaroa Lighthouse 1880
Yes, there are some very interesting (and remote) old lighthouses.
Can you really call it the "clean power of gravity" when the keeper's effort is what lifts up the drive weight. It was clearly a thankless job :Dgreendoor wrote:A lighthouse keeper's job must have been very physically demanding - constantly winding up that weight... In this day of electric motors and stuff, it's refreshing to see the clean power of gravity at work...
Following on from Pequaide's basic theory ... i'm wondering what happens if a heavy flywheel is accelerated with a small falling weight, if no attempt is made to limit the speed. I'm thinking of a large vertically mounted balanced flywheel - as massive as can be afforded. Then a much smaller diameter pulley fixed onto the same shaft, and a long rope coiled up on this pulley.
If the massive flywheel is perfectly balanced, and the bearings are very low friction, a very small weight hung from the rope should be able to accelerate the flywheel. Due to the big difference in diameters, the weight should be able to apply acceleration force to the flywheel for a reasonable period of time. (Much longer than typical weights located at the rim).
I'm thinking that this very small weight should apply constant acceleration, so the longer we can draw this out the better. After a while, the maximum possible rotational speed should be obtained (and much cleverer people than myself could calculate what this might be). Since momentum is mass * velocity, the longer we can leave this to gather momentum the better.
Once the weight reaches the end of the rope - the wheel will have maximum momentum. I would wonder if all that momentum could be used to winch up the weight very quickly (perhaps by means of another rope, this time winding around the outside diameter of the flywheel).
Conservative wisdom would say that this would never self sustain. We would simply work on the established assumption that energy can't be created, and therefore without doing any experimental work we would loudly proclaim that any energy obtained from the free fall of the weight would be required (and then some) to lift the weight back up.
But is that really true?
At this stage, i'm not really concerned with an elegant solution. Having to wind up a coiled rope each time doesn't worry me, because obviously the energy cost in winding up a rope (or nylon string) and sending that back up to the top is trivial. The question is whether there is any excess energy to be gained ...
And yes I know what the conservative answer is. But has anyone actually tried anything similar, because I think Pequaide has made some extremely interesting observations and calculations concerning overbalanced Atwood machines etc that suggest there could be something here.
If the massive flywheel is perfectly balanced, and the bearings are very low friction, a very small weight hung from the rope should be able to accelerate the flywheel. Due to the big difference in diameters, the weight should be able to apply acceleration force to the flywheel for a reasonable period of time. (Much longer than typical weights located at the rim).
I'm thinking that this very small weight should apply constant acceleration, so the longer we can draw this out the better. After a while, the maximum possible rotational speed should be obtained (and much cleverer people than myself could calculate what this might be). Since momentum is mass * velocity, the longer we can leave this to gather momentum the better.
Once the weight reaches the end of the rope - the wheel will have maximum momentum. I would wonder if all that momentum could be used to winch up the weight very quickly (perhaps by means of another rope, this time winding around the outside diameter of the flywheel).
Conservative wisdom would say that this would never self sustain. We would simply work on the established assumption that energy can't be created, and therefore without doing any experimental work we would loudly proclaim that any energy obtained from the free fall of the weight would be required (and then some) to lift the weight back up.
But is that really true?
At this stage, i'm not really concerned with an elegant solution. Having to wind up a coiled rope each time doesn't worry me, because obviously the energy cost in winding up a rope (or nylon string) and sending that back up to the top is trivial. The question is whether there is any excess energy to be gained ...
And yes I know what the conservative answer is. But has anyone actually tried anything similar, because I think Pequaide has made some extremely interesting observations and calculations concerning overbalanced Atwood machines etc that suggest there could be something here.
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georgexbailey
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re: Akaroa Lighthouse 1880
@greendoor - I tried a simlar experiment a few months ago and the flywheel was not able to lift the weight back up. But, my experiment was not real accurate so I would not say it was 100% conclusive.
GB
GB
re: Akaroa Lighthouse 1880
frankly I see a generation gap here!
Weights and flywheels, discs and pucks. Is the days of a good old wooden Duncan YO-YO gone for good?
Ralph
Weights and flywheels, discs and pucks. Is the days of a good old wooden Duncan YO-YO gone for good?
Ralph
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georgexbailey
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re: Akaroa Lighthouse 1880
What is a yoyo? :)
re: Akaroa Lighthouse 1880
I though everyone knew what a yoyo toy was. Does it go by a different name in other countries?
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re: Akaroa Lighthouse 1880
I think George was joking. The :) gave it away :D
Ralph's reference to the Yo-Yo seems about right, though.
Ralph's reference to the Yo-Yo seems about right, though.
re: Akaroa Lighthouse 1880
Greendoor; momentum is conserved but force is not necessarily conserved as momentum. Lets say that the mass is in the rim even though the hanging mass or force is next to the axis. Just for simplicity let’s say that the hanging mass is one tenth of the distance to the mass of the rim. From this position the force would apply one tenth of the force that it would apply if it were hanging from the rim. Where does the other nine tenths of the force go? Well it is applied to the bearing, the stationary bearing can not move (up and down or sideways) and it pushes back. Or more precisely; the bearing pushes on the frame, the frame pushes on the floor, and the floor pushes back. These are balanced forces that have no affect upon the motion of the rim.
If the hanging mass was on the rim and was one ninth the mass of the rim (total mass is ten) the acceleration of the rim would be 9.81m/sec² * 1/10 or .981. But the hanging mass is near the bearing and is applying one tenth that much force to the mass of the rim, therefore the acceleration of the rim would be 1/10 .981 or .0981. This is a small amount of acceleration but it is to be noted that the hanging mass is moving one tenth as far down as the rim is moving at .0981m/sec² in rotation. That means it will have ten times as long to push the rim at one tenth the acceleration (.0981) before it moves the same distance as if it were in the rim working at .981. So the acceleration is a tenth slower but the time over which the force acts is ten time longer, so I am guessing we are back where we started. I am going to guess that the final momentum of the rim will be equivalent, whether you drop the mass from the rim or drop it from near the bearing.
So the system should have the same amount of momentum if you drop near the axis or from the rim. So after the mass, hanging from a string near the axis, has dropped your chosen distance; changing its position to the rim should not make any difference. It will rise only to the point from which it was dropped from either position (ideally). But there is probably more bearing friction in the slower movement.
If however you use the cylinder and spheres phenomenon and give all the motion of the rim to the dropped mass then you have major increases in energy.
Good post greendoor. It is amazing what they accomplished with what we now consider crude tools and instruments.
Oh: NASA called the cylinder and spheres phenomenon the yo-yo de-spin device.
If the hanging mass was on the rim and was one ninth the mass of the rim (total mass is ten) the acceleration of the rim would be 9.81m/sec² * 1/10 or .981. But the hanging mass is near the bearing and is applying one tenth that much force to the mass of the rim, therefore the acceleration of the rim would be 1/10 .981 or .0981. This is a small amount of acceleration but it is to be noted that the hanging mass is moving one tenth as far down as the rim is moving at .0981m/sec² in rotation. That means it will have ten times as long to push the rim at one tenth the acceleration (.0981) before it moves the same distance as if it were in the rim working at .981. So the acceleration is a tenth slower but the time over which the force acts is ten time longer, so I am guessing we are back where we started. I am going to guess that the final momentum of the rim will be equivalent, whether you drop the mass from the rim or drop it from near the bearing.
So the system should have the same amount of momentum if you drop near the axis or from the rim. So after the mass, hanging from a string near the axis, has dropped your chosen distance; changing its position to the rim should not make any difference. It will rise only to the point from which it was dropped from either position (ideally). But there is probably more bearing friction in the slower movement.
If however you use the cylinder and spheres phenomenon and give all the motion of the rim to the dropped mass then you have major increases in energy.
Good post greendoor. It is amazing what they accomplished with what we now consider crude tools and instruments.
Oh: NASA called the cylinder and spheres phenomenon the yo-yo de-spin device.
Thanks Pequaide - appreciated. Yes - prolonging the time was the point of having the smaller inner diamter, and i'm aware that the force would be proportionally smaller. What I was really wondering is whether the flywheel could still end up with a significantly higher velocity because of the longer time exposure ... basically using the inertia of the larger flywheel to slow down the fall of the smaller weight ...
I'm still trying to get my head around the cylinder & spheres effect - i'll google on yo-yo des-spin device, thanks.
I understand what a Yo-Yo is. What I described is not a Yo-Yo. A Yo-Yo is simply a flywheel, with string coiled around one diameter, and the energy gained while falling & winding down is nearly equal to the energy required to wind it back up. Clearly no potential for overunity.
What I was describing is a stationary flywheel, with a much smaller weight falling (like a clock or lighthouse engine). So two seperate masses instead of one; the use of different diameters for winding up and winding down, to achieve a time differential - in the hope that delaying the fall of the small weight might allow acceleration to accumulate more velocity ...
I'm still trying to get my head around the cylinder & spheres effect - i'll google on yo-yo des-spin device, thanks.
I understand what a Yo-Yo is. What I described is not a Yo-Yo. A Yo-Yo is simply a flywheel, with string coiled around one diameter, and the energy gained while falling & winding down is nearly equal to the energy required to wind it back up. Clearly no potential for overunity.
What I was describing is a stationary flywheel, with a much smaller weight falling (like a clock or lighthouse engine). So two seperate masses instead of one; the use of different diameters for winding up and winding down, to achieve a time differential - in the hope that delaying the fall of the small weight might allow acceleration to accumulate more velocity ...