h a l f b a k e r yIncidentally, why isn't "spacecraft" another word for "interior design"?
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This muscle-powered, yard vehicle consists of a bench for two adults or three kids suspended from the axle of two ten-foot wheels. Each pair may be rubber-tired, aluminum alloy with bicycle-type spokes or classic, oiled, oak and hickory wheels. A system of clutches and controls determines if the swing’s
axle rocks freely or is engaged to one or both of the wheels.
To move forward, the swing rotates uninhibited until it is at its highest point forward and starts to swing backwards. The clutches on both wheels lock to the axle and the entire conveyance rolls forward. This is automatically repeated for each swing. Reverse rolling is done in the opposite manner. By locking only one wheel at a time, pivoting is accomplished in any direction.
After touring the estate, a pair can disengage the clutches and gently rock and roll, while observing the sunset from the best viewpoint. A porch swing model mounted on wheeled A-frames is also available for circuits of the wrap-around porch.
(?) sketch
http://www.geocitie...ohnnie/wheeler.html
[FarmerJohn, Oct 05 2004, last modified Oct 21 2004]
(?) Glder rocker patio set
http://www.cedarsto...liders.html#fanback
Bottom of the page [2 fries shy of a happy meal, Oct 05 2004, last modified Oct 21 2004]
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<Pardon my French>
Abso-fuckin'-lutely Brilliant
</Pardon my French> |
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Excellent, but I think you would need bigger wheels - 10' wheels would (naturally) have a radius of 5', so you would be looking at a swing with a 3' to 4' chain, which would swing back and forth at a vomit-inducing speed. |
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Would multiple independent seats, swinging out of phase, give a smoother ride? |
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I eagerly await your sketch. |
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<Pardon my French>
Abso-fuckin'-lutely Bee-yoo-ti-ful
</Pardon my French> |
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Not certain it will actually get much of anywhere. The swingers are suspended by the support rod, which supplies enough balance to the centrifugal 'force' from their swing along the line of the rod, which can be broken down into horizontal and vertical force components. The vertical is simply wasted into the ground, whereas the horizontal is what you're after in order to propel the assembly. |
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In order to 'pump' a swing to go higher, a person must be able to have the swing be relatively stationary with respect to his plane of reference, for he is adding to that centrifugal 'force.' The device suffers from the fact that the swingers will never be able to actually get up, but will just be moving the wheels back and forth due to that dynamic and unrestricted horizontal force, and probably won't get anywhere, or at least not like in the drawing. They might be able to get a little bit of swinging action simply due to frictional rolling resistance, which they can use to their advantage with a racheting clutch system, but it won't be much. |
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Try this: tie a length of string about half a meter long around some cylindrically-shaped object, like a thread spool. On the other end, hang a small weight. If you have a dining room table that has a split leaf, fish the string through the split, so that the thread spool can roll back and forth along the crack of the table, with the weight hanging below. Now, pull back on the pendulum and set it in motion and note what happens to the spool. As it rolls forwards, it effectively deadens the pendulum's swing quickly. It will even roll backwards initally, and in a frictionless environment, would come to rest in the center of gravity of the entire assembly. |
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Now, if there were some way for the spool to be prevented from rolling backwards, like an external frame that always stayed parallel to the ground somehow, like a standard bicycle, then a clutch could be added to the main wheel axis as well to prevent that. |
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Who let the engineer in? :-) |
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The bouncers weren't at their posts... |
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I'm gonna have to fire them..... |
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I want to make one of these. Huge freewheeling croisant, FarmerJohn. |
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RayfordSteele] If the chains were not chains at all but solid, (though flexible) rods, and the pivot point on the axle had a ratchet mechanism only allowing the swing to move forward, then it should work just like the drawing shouldn’t it? Have individual brakes for each wheel and you would have efficient steering as well. |
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I am not an engineer so I could easily be wrong, but it seems to work in my head. |
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That's because you have enough vacant space in there to get a good swing ;-) |
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Ouch.
Close to the mark, but ouch. |
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As soon as I started reading the idea I didn't picture a swing at all, but one of those patio table glider rockers, {link}, with wheels being driven like a locomotive that the whole family could take for a ride. |
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Aw, I'm only kidding. Really. |
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Still close to the mark. :) |
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RayfordSteele: Whoops, I shouldn't have gone to bed before 2 A.M. I did some testing of this with a plastic erector set, at the time. I agree that swinging will be a chore with a mobile "swing set", therefore the //rock and roll// when at "rest". The inertia of the wheels and some rolling resistance will allow the riders to self-pendulate. At the point shown in the sketch, the unit is locked (includes stiff rods), and its center of gravity is ahead of its ground contact, causing it to roll forward. The clutches cannot bleed off all of this energy or there wouldn't be any swing rotation left. |
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FJ's pic: Hurrah! Now I'm happy. |
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As for steering, the method that spings to mind is some kind of differential on the axis - a better engineer than me (to whit - someone who made the leap from StickleBricks to Lego) could sort out the details. |
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Bubya, you're missing my issue. The clutches don't do anything to prevent the entire wheel assembly from rolling, however. What won't work that well is the the swing pumping action. In order to pump, the pivot point must put up some horizontal resistance. Otherwise you simply roll forwards a little, and then backwards a little. |
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What I want to know is, how do they get up to the point in the drawing in the first place? The accumulated energy to get them there is continually drained off by the moving of the pendulum swing point, so they never any higher than the point of imminent movement allows. If you don't want to go to the trouble of my demo, just swing a string and a weight with your hand, and as the pendulum is swinging forwards, move your hand forwards as well. It will nearly deaden the motion. The clutches don't bleed the energy, the rolling does. |
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"Bump stop" Wheel chocks that set to the ground during those parts of the swing forces that tend to move the rig backwards? |
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RayfordSteele: We all agree that swinging can be started and accelerated on a stationary swing on an ordinary support, by using the legs and upper body. Of course some of this energy is lost as the wheels roll back and forth, but not all as they’re continually changing direction. The swinger is utilizing their inertia to maintain and increase movement. |
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I disagree with your example of using indeterminate, external force (moving the pivot with the hand) to stop a pendulum. I compared the time a pendulum keeps swinging on a fixed axle to the same pendulum on the axle with free rolling wheels. The latter time in this unscientific test was only one third shorter (it didn’t stop instantly!) than the former time. Though this would indicate that the idea is not practical for the real world, it should fit in here. |
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bristolz: Now there’s a practical and brilliant fix! |
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Only a third? Interesting. I withdraw my objection then. |
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The man is a croissant attractor! Well I have come to humbly add my offering to the pile. |
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Is all this pastry making you fat? |
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A new singularity? French-body radiation? |
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Well, I find the whole thing just filthy. And even it it were so acceptable to rotate uninhibited, I don't think of a pair of swingers would disengage clutches before gently rocking and rolling. |
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bris, lookup alternate definition of 'swinger' for the key to rowlycat's anno |
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I thought maybe [rowlycat] had an aversion to bicycle grease or whatever they use on these things. |
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How about incorporating a gyroscope, a la Segway™? Wouldn't this provide a resistive stable force against which the swing could swing? |
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Bicycle grease certainly won't congeal as easily, you might even be able to re-use it. |
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Holy comment page....I love the idea. Love it. You get to swing AND roll around! But you can't steer. That's bad. However. You *could* *in theory* make the wheels into big squares, which, through a series of gears, make little wheels spin on the bottom. Those wheels would move you. Then you might be able to steer something. I don't know, I guess you would actually drift to the left/right without turning left/right. Still, I give you a [+]! |
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Add a third, rudder wheel in back to steer. It would also make the system more stable. Design in a ratchet mechanism similar to that found in a bicycle that allows the swingers to freewheel on the forward swing and drive forward on the backward. |
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A similar, fun idea would be a rocking chair wheeler, that would allow the occupants to "rock & roll"!! |
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