h a l f b a k e r yA few slices short of a loaf.
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Imagine a pogo stick that uses a pneumatic piston, rather than a spring as the bouncing mechanism. In addition to bouncing, the piston also pumps air in a separate reserve cylinder, in much the same way that you pump up a tire (or tyre).
After a sufficient pressure has built up in the reserve cylinder,
the rider presses a button that releases the pressurized air back into the piston, launching stick and rider high into the air. If the rider bounces 50 times before pushing the release button, the subsequent super-bounce is five times higher than normal!*
The rider who leans forward at 45° may find himself launched down-range as far as three meters! Useful for jumping moats, or safely crossing busy streets.
*With each regular bounce, about 10% of the energy is used to pump up the reserve cylinder, 80% of the energy is returned to the next bounce, and the remaining 10% is lost to friction.
Pogo matic
http://vehicle.me.b...cgee/pogomatic.html
The Berkeley Robotics and Human Engineering lab has built something very similar. [krelnik, Oct 05 2004]
BowGo
http://www-2.cs.cmu.edu/~bowgo/
Another super-powerful pogo stick, this one from Carnegie Mellon. [krelnik, Oct 05 2004]
The Flybar
http://www.flybar.com/pages/index.html
4 to 5 feet of air on a jump, they say. [bristolz, Oct 05 2004]
PSEUS (Pogo-stick Extreme of the University of Sherbrooke)
http://www.gme.usherb.ca/pseus
A Canadian group is going for the world record. [jutta, Nov 06 2007]
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Sorry, but please explain your mechanism in more detail. Let's say you get up to x psi at the lowest point in your bounce. How do you increase the pressure in your reserve chamber larger than x? |
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I don’t think it’s necessary to increase the pressure in the reserve chamber above the maximum pressure in the piston. They reserve cylinder may have more energy stored in it than the piston at maximum compression if the reserve cylinder has a greater volume. |
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I figure a 1 L cylinder pressurized to about 650 kPa (6.5 atm or 100 PSI) would launch a 70 kg pogoist about 2 m vertically. |
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Now that I think about it, there should be very high pressure in the reserve cylinder, because there needs to be a high pressure differential between the reserve cylinder and the jumping piston. This can be achieved by having a separate piston to pump up the reserve cylinder, with a very small cross-sectional area, so that it does not move much air with each pump, but can produce very high pressure. |
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A cylinder with a volume of about 0.1 L and pressure of 7000 kPa (70 atm or 1000 PSI) would have more that enough energy to jump 2 m vertically. |
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Some folks at Berkeley have built something similar, but I believe it uses an external air source. See link. |
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Build this in shoes, and one could make a good spurt at the end of a race. |
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Race? I would think it would be much more applicable in basketball or the high jump. |
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Instead of counting hops, I'd just like a guage on the handle that tells me when there's enough air stored up to jump higher. I forsee kids hopping over cars. + |
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