h a l f b a k e r yIncidentally, why isn't "spacecraft" another word for "interior design"?
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Take a standard basketball. Cut a flap in the top.
Put inside:
* A small solenoid which pushes against the bottom surface of the ball
* A microswitch or peizo sensor between the solenoid and the bottom of the ball
* A pendulm swung in two axes by model servos
* Some electronics
* Some batteries
Seal
the flap, blow up, and prepare to gasp with astonishment like a breathless carp.
The solenoid is activated by the microswitch which closes every time the ball bounces. The length of pulse delivered to the solenoid is controlled with the third channel of the remote, adjusting bounce height. Tilting the pendulum shifts the centre of gravity, rotating the ball so that the next impulse from the solenoid has a horizontal component.
Taa-daa... a radio controlled self-bouncing phantom basketball with uses and variations so many and various, I could not possibly list them.
Bumble Balls
http://www.rcertl.c...2/bumble_ball.shtml
Similar, but lumpy. [Mr Burns, Sep 23 2002]
Self-Bouncing Ball
Self_20bouncing_20ball
A similar, less-directionally-dependent design using air pressure [joee, Jan 05 2006]
[link]
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But you'd need the thing to always land on either end of the solenoid (can we just call it a spring?) - gyroscope? (but then you'd have problems with direction..) |
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Not too many electronics, or it might try to dock with the international space station. |
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Wouldn't it be significantly heavier, thus making it hard to use and play with? You would also have to counterweight it so the weight isn't too lopsided. |
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Sounds like dribbling with a rugby ball or American/Australian football. |
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Needs a power supply. A battery would easily be too heavy to power the solenoid AND not be ludicrously overweight (He shoots a brick!). I suppose the ball could be inflated with some Helium to try and compensate. But I think there is more chnace of a genuine phantom playing B-ball than this working. |
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[BC],[yama] The mass of the solenoid etc shifts centre of mass to the bottom so that the ball would stay upright and would always impact the ground within a "sweet spot" about 50mm diameter.
[Jinbish] I estimate mechanical power of 0.2J per impulse at 1Hz bounce rate to keep a basketball bouncing on a good surface, even with pessimistic solenoid efficiency this means electrical power is in the single AA battery range (<1W). I guess two AA's would power the solenoid and the servos for an hour. The volume of a basketball is too low for helium to have any appreciable effect. |
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One thing I should have made clear, the ball is not meant to be used by humans like a normal basketball- it is more of a novelty. |
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I envision a gyro-top or flywheel at ball's dead center that would serve to keep a microswitch open except under force, so this would work -- in my mind anyway. Heavier parts and more efficient mechanisms could improve on the ultra-light components I'm thinking of. A more efficient model could have the reserve momentum to be self correcting to a degree. Better ability to right itself could allow the ball to gain stability after a less-than-perfect launch. |
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Some of the recent bakerish has been worth sitting up to the design desk for a little perspectival analysis. Thanks to newbies for the suggestions, and welcome to Halfbakery, ¯shameless_self_reference (May you not have to often sign your name longhand!). |
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Try mounting an electric motor that's geared to a strait rack. Both motor and batery pack travel the length of the rack, back and fourth on the ball's diameter. When the ball is first dropped, the motor and batery weight will drop to the bottom of the rack and trip a switch that quickly sends it back to the top producing a 'bounce'. |
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Now, if the rack were gimbaled inside the ball so it always points up, then no matter rotation of the ball, it would always bounce straight up. Add a gyro to the gimabal and you could direct the ball. |
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[Embeecon] nothing else here in the last 4 years has caught your imagination? |
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