h a l f b a k e r yRenovating the wheel
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A sphere made of a transparent membrane and a lightweight frame, similar to a geodesic-dome camping tent. The participant is suspended from bungee cords at the center of the sphere.
The diameter of the sphere is designed to create the required amount of aerodynamic drag and also to allow the participant
to be displaced from the center by the bungee cords if the sphere impacts something hard (such as the ground).
Now, either roll this off the edge of a cliff or down a steep slope, or toss from an airplane. If rolling on the ground, the participant should be attached by a swivel (so he tends not to spin), be slightly below the exact center of the sphere, and be able to move his mass from side to side, for some semblance of steering control. And watch out for trees and traffic.
Sean Connery used something similar in an earlier James Bond film, but it wasn't transparent and he wasn't suspended.
But the spinning is the fun part...
http://www.zorb.com/
Often linked here... [RayfordSteele, Oct 04 2004, last modified Oct 21 2004]
Hot-air balloons falling
http://groups.googl...etnews03%26rnum%3D1
Reports from the field [flypaper, Oct 04 2004, last modified Oct 21 2004]
Ultraball
http://www.halfbakery.com/idea/Ultraball
Courtesy of [saker] - Similar [Shz, Oct 04 2004]
(?) Zorb
http://www.zorb.com/thumbnails.htm
..looks like a good time.. [bpilot, Oct 04 2004, last modified Oct 21 2004]
(?) Bubble dork
http://www.youtube....S98&feature=related
[doctorremulac3, Dec 05 2010]
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Annotation:
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Q: What's to ensure that the sphere is upright when it hits the ground? |
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QQ: What does upright mean to a sphere? |
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I see limitations in how much damage the frame can take ... parachutes are cool because its not such a rapid deceleration ... if you need a corpse for testing, I'll gladly let you have mine! |
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Hmmm, From my (rusty) fluid mechanics drag force on a sphere is 6*pi*viscosity*diameter*velocity, so with viscosity of air at 1.7e-4 g/cm.s and a terminal velocity of, say 10m/s that yields 300m diameter for a 100Kg sphere + Payload. That's a BIG sphere.* |
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Spheres are really quite slippery shapes at low Reynold's numbers. |
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*...of course you could make it of something slightly elastic and pressurise it to make it bounce when it lands... |
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The link above has some empirical figures for hot-air balloons falling and reaching terminal velocity with their gas burners off. Interestingly, the range of those velocities, from 800 to 1300 ft/min, or about 9 to 15 mi/hr, is equivalent to jumping off a wall between 3 to 7.5 ft high. Googling for parachute landing speeds I found figures like 13 mi/hr. A 60,000 cu ft balloon would be about 60 ft in diameter, and of course not a sphere, but teardrop-shaped with the burner hole at the bottom. |
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Upright = not oriented so the sphere-o-naut lands on his head. |
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I like the idea of being in freefall with no wind, dressed in jeans and a t-shirt. Or naked. No, maybe jeans and a t-shirt. |
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Better to make the sphere inflatable
rather than framed, that way the
structure won't break and you have a
giant airbag protecting you.
The big problem is that you would need
a biiig sphere. I seem to recall an old
style jumping parachute is about 40' or
so in diameter, and that would have
more drag than a sphere. You would
need an even larger sphere to get a
similar falling speed, although you
would have the sphere absorbing the
impact rather than your knees. |
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fill the big elastic sphere with helium,
suspend the sphere-o-naut in his or
her own air-filled sphere, attached by
bunjees, and you could get a lot more
bounce. i'm thinking slow-mo, like
men jumping on the moon. |
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I saw something similar in a Jackie Chan movie. The intro shows him on a powered parachute, and then he gets to a cliff, lands the chute and discards, and inflates this gigantic clear ball. The ball itself was constructed in cells, like a soccer ball(football). Jackie wiggled inside, and rolled himself down a steep rocky mountain. I hate Jackie sometimes. He gets to have all the fun. |
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See link for the thing Jackie was rolling
in. |
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BTW, anyone know which in which
movie Jackie jumped *into* a
stepladder? |
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//if the sphere impacts something hard (such as the ground)// |
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What are the alternatives? |
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Float away, and never be seen again. |
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[bpilot] Shanghai knights. |
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[destructionism]: Armour of God |
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Sounds like fun, but I'll keep my parachute. It glides a bit better than a sphere, and the unobstructed view is great. It would take almost fifteen minutes to fall 13,000 feet at a "safe" velocity for impact (~10 mph), during which time you'd be subject to the winds aloft, and you'd be unable to control your landing point. |
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[GPL], that's it! Thanks. Gotta find a
copy. |
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[Freefall]: Yeah, but the sheer terror alone, wondering if you're going to land in that fluffy field or the nearby foundry, would be pretty cool. |
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I've had experiences where the winds were so far from what was measured only twenty minutes before that I wasn't sure if I was going to make it back to the drop zone, was going to come up short in the lake, come up shorter in the power switching facility, or if I should turn around and land in an off-site field. |
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(I chose the field. the long walk back was infintely preferable to a death by electrocution)) |
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The wonder was most assuredly not fun. |
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Re: landing on that foundry, etc.
Drop the skydiving sphere offshore for
collection by boat. This pastime is
getting a little expensive, though. |
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Drift seems to be a big problem in this idea. If the sphere was stable enough, and strong enough, control surfaces could be added facing downward, into the relative wind. Then, with your controls on the inside, you could angle them both slightly forward to go forward, backwards, and opposite to roll the sphere to a different heading. |
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Another problem is getting down at all if you catch a good thermal. You can stall a parachute and descend rapidly, but you can't stall a helium sphere. |
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Shirley the passenger should be suspended in a gyroscope rather than bungee cords. This would allow the passenger to control their orientation within the sphere. To accomplish this, the frame of the gyroscope would need to be rigid, which would be difficult for a sphere that deforms as it bounces. To accomplish that, we need to introduce the concept of having an inner (rigid) and outer (deformable) sphere. |
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Fortunately, this will be impractical to implement. We need to add a large network of dampers to absorb the impact between the inner and outer spheres. Assuming the sphere makes contact with the ground, the dampers toward the ground would absorb energy on compression, and the dampers towards the sky would absorb energy upon extension. [+] |
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If the devices consists of two concentic spheres, joined by numerous bungee cords, then the gap could be rapidly filled by a cool-burn pyrotechnic gas generator. |
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This would effectively be a "parachute" that could be used by a completely untrained person. Climb in, zip up outer and inner ports, jump. Static line triggers gas generator; float slowly down. |
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Hot air balloon fabric would be fine - it doesn't need to be truly airtight, the pressure difference will be small. |
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On landing, both the bungees and the pressure within the double wall will act to absorb inpact energy, and because of the low terminal velocity that impact energy will be modest. |
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I liked this and was going to suggest 2 concentric spheres, the central one being where the person is and the first being a shock absorber when it hits the ground. 8 beat me to it. |
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I was thinking it would be all one material but joined the way soap bubbles link together when somebody puts on one of those soap bubble shows and blows smoke into the center one. |
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That's where the person would be. |
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Neat idea but not super practical. |
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Contact velocity could be significantly higher than a traditional parachute, since the sphere collapsing under the passenger would absorb energy that is presently only absorbed by the parachutists legs. |
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Depends on the size of the outside ball relative to the weight of the guy inside. |
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But I'd think it would have to be pretty big. A parachute scoops the air and lets a little bit escape out the top to retain it's shape. The ball would just be pure aerodynamic drag. It's also a lot more material than a chute which would add to the weight. |
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Also, if it's got enough area to slow a passenger's vertical decent, that same area would be very susceptible to cross winds and this thing might fly horizontally a lot more than a chute. |
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Over the sea, it would float a lot better than a 'chute. Could be adapted into a liferaft. |
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