h a l f b a k e r yGuitar Hero: 4'33"
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a flywheel with square hollow spokes with
sliding square nuts inside. each nut has a
threaded rod through it with a gear
mechanism at the center of the wheel to
turn said threaded rods. this will allow a
constant torque on the flywheel to have a
variable moment of inertia, and thus a
variable
rate of rotation.
Newer idea in anno- 5-21-07
bicycle with speed governor
bicycle_20with_20speed_20governor
[xaviergisz, Aug 14 2006]
[link]
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...or a constant rate of rotation as momentum is changed. There will be plenty of strain on the threaded rods. |
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//There will be plenty of strain on the threaded rods// |
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that depends on the rate of rotation. perhaps linear actuators would be better? |
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Isnt this exactly what a centrifugal Governer is in a slightly different form. |
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no,this is within the wheel itself, essentially traveling in only 2dimensions. but yes, it is exploiting the same rotational motion properties. |
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What [bleh] is doing, though, which is different from the Watt's governor is that Watt used rotation speed to increase moment of inertia which, in turn, reduced rotation speed - classic negative feedback. If I understand correctly, [bleh] is using external input (to the linear actuators) to control the moment of inertia, and thus rotation speed. Which is a little cool. |
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Would you leave the weights extended at idle and the move them inwards under power --- so that there is smooth idling and better acceleration? |
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Or are you trying to store energy? |
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I was thinking forenergy storage in a system with a variable driving force. as [angel] said, the idea is to control the moment, not just have it vary with rotation. |
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[bleh] If it's any kind of useful flywheel, no known thread could hold the nuts on. (I'm assuming your nuts have some meaningful mass if you are using them to alter the moment) |
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from earlier (first ) anno
//
//There will be plenty of strain on the threaded rods// |
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that depends on the rate of rotation. perhaps linear actuators would be better?
// |
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I saw the anno and your response. |
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not trying to be a smartarse, it just happens. :) what is a typical rate of rotation of a 'useful' flywheel? would linear actuators be better? my question was never really answered. is the [-] for being a smartarse or because you dont like the idea? |
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ok, obviously im no engineer, lets see if
i understand this correctly. |
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energy E=.5I(w^2), I is moment, w is
rate of rotation.
lets assume said flywheel is reved up
with weights pulled to the center. when
generator is engaged, a certian energy
would be required to turn the
generator. |
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if we assume a constant negative
acceleration (slowing down), we can
vary the moment to maitain a constant
E as w decreases . i.e. as the wheel
slows down, the weights extend so that
energy output stays constant. |
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again, i only half know what im half
baking here, so im at best a quarter
compitent, so please correct me if i am
wrong. also, this is purely theoretical as
i have no idea about materials and
strains and the like. |
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why do i always loose votes when i explain myself? |
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I thought that the purpose of a Watt's governor was to have the rising weights operate a throttle which would cut back on the engine's power, while imposing minimal frictional load on the engine when the speed limit was not exceeded. |
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Having a variable-moment flywheel could be useful for dealing with certain types of variable energy supplies or variable loading. |
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I’ve been thinking about this again
recently. Instead of using nuts on
threaded rods or linear actuators, take a
ring, slice it into many equal pieces and
place each piece on a pivot. These
pieces could then be rotated so that
they point essentially radially out from
the center. They would be locked into
this position by a retractable pin. The
end closest to the center could then be
weighted. Since a rod has a lower
moment of inertia than a cylinder or
ring, and the majority of the weight is
nearer the center, is should be easier to
rev up to speed, then when the desired
RPM is reached, the pins would be
retracted allowing the pieces to swing
back out and snap back into their ring
shape. I’m thinking the ring should be
sliced non-radially so the pieces overlap
when in ring shape. |
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Your weighted rod idea can be simplified by offsetting the pivot point, so that the center of mass of each rod is inboard of the pivots while collapsed, and even with the pivots when extended. |
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This will not work as you state. While it is true that this assembly will have a lesser moment of inertia in the collapsed position, thereby allowing it to be revved to a given RPM with less input, the RPM will drop as the rods are extended to the ring configuration due to the conservation of angular momentum. |
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p.s. Thanks for not using the ice skater
analogy to demonstrate my ignorance. |
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