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DARPA Develops Dolphin-like Tail For Divers
willatnewscientist writes "Forget flippers, the latest idea from the guys at DARPA is a tail-like prosthetic for divers. The (forward-facing) tail, demonstrated at DARPA Tech 2007, is designed to help a diver maintain a speed of 2 knots for up to 300 metres. 'The unpowered, carbon-fibre structure straps to a diver's shins and is used with a motion that is not unlike the way Patrick Duffy swims in The Man from Atlantis. The design is inspired by the way mammals like Seals and Dolphins swim. I caught this video of Powerswim (3.5 MB .avi) at the DARPATech 2007 gathering in Anaheim, California. It would be nice to grab one and try it out when I next head down to the beach, but unless its designers DEKA (the same people who make the Segway) come up with a budget version, the $500 price-tag is going to keep me firmly in my flippers.'"
For those of you not as comfortable with knots and meters(and with the help of google)...
2 knots = 3.37561971 feet / second
300 meters = 984.251969 feet
So it's about 3.4 feet/s over 984 feet.
Takes about 289 seconds, or 4 minutes 49 seconds.
Honestly, that's not as fast as I'd expect from DARPA equipment. Nor does it really have great endurance. *shrug* It's cool, don't get me wrong, but it seems like it'd be a long way away from USEFUL except in very, very specialized situations. Help me out, I can't actually think of any times where you'd want something like this if it only lasts 300 meters. In the time you're strapping that to your legs I'll already have swam most of the way there at a leisurely pace(and as a bonus, I don't have some dolphin fin to remove when I arrive.
Not a lot of information available, but found this http://www.darpa.gov/dso/thrusts/bio/biologically/ powerswim/index.htm/ that states that this device is 85% efficient, whereas typical recreational fins are only 10% efficient. Interesting, but does that mean that the device is going to be 75% more difficult to use that regular fins?
Ahhh, what an awful dream. Ones and zeroes everywhere... and I thought I saw a two.
To put the speed in perspective, 2 knots/hours is roughly double the speed of the world record holder in the men's long course 800 meter freestyle. Even allowing for fins, and for being under water, I rather doubt you could swim that far, that fast, with your legs.
Plus, of course, if a person could swim that far, that fast, with their legs do you really think DARPA would have spent the money do develop this device?
The monofin is longer and narrower so it has more parasitic drag. This device is more like a high aspect ratio sailplane wing, while the monofin is at best like an old style hang glider.
http://michaelsmith.id.au
Outrun a shark? At 2 kph for 300 feet?
Methinks you aren't very familiar with sharks. A blue shark for instance is good for about 39 kph. In other words, if it wants you, you'll be had.
I've fallen off your lawn, and I can't get up.
Personally, I think that a $500 price tag will result in this gaining widespread use, assuming it's as useful as the article states.
;-)
I've been diving for a couple of decades and this includes rare specialties where covering a lot of distance is useful. For normal recreational diving traveling around fast generally indicates a newbie. The point of diving is to enjoy the scenery and as divers become more experienced they generally slow down and become "lazy" and try to leverage currents and surges as much as possible.
A dolphin kick is something that divers occasionally do with normal fins to vary muscle usage and avoid fatigue and cramps. So many of us are somewhat familiar with the general style. The problem with this style is that it is quite limited with respect to maneuverability. Divers often use their legs/fins asymmetrically or at odd angles. This far more useful than going fast.
Finally, anything that makes your silhouette look even more like a seal to a shark is a bad idea.
Swimming Machine
"Flex your legs, then kick out -- the Aqueon swimming machine enables you to out-speed an Olympic swimmer, says Pan Western Research. As your legs move, the forward plane rises and falls." -- Popular Science
(Popular Science, "What's New", June 1974)
You can see the old flyer at Innerspace Corporation.
Spoken like a true Jaws watcher who's never actually seen a shark in real life. I have, and I can tell you that it's *damn* hard to get anywhere near them, as they are far more afraid of you than you are of them.
You're also wrong about shark vision, many sharks have excellent vision. They are also quite intelligent, research (that I can't be bothered finding links on) has demonstrating sharks solving problems that were previously thought to be beyond them. They're not exactly going to be April fooling Flipper, but they aren't the mindless ocean dwelling mulchers that you seem to think they are.
Sharks also almost uniformly go for dead or dying fish. They are predators of opportunity. Only the great white is a habitual predator, and even then it will not attack prey that it feels can fight back. So in short, if you have a tiger, bull or bronze whaler shark circling you and eying you the way you'd eye a McDonalds burger (although I think the average human would be healthier than McDonals), swimming confidently towards it would likely scare it off. If not, a punch in the nose or gills is almost certain to do so. I'm not saying it's foolproof, but its better than scrambling to the surface like a panicked seal. If you have a great white circling you, looking hungry, the same tactic would work, only pray first. Jokes aside, sharks of any species are hard to approach. If you're diving and you see one, you're lucky, not unlucky. They can sense you well outside visible range, and they know you're not food and will avoid you before you even knew they were there. I really wish I saw more sharks on the dives I've done, and plan on going shark watching more. They truly are beautiful creatures.
We don't look anything like food they're used to, we smell funny, give off all kinds of weird electrical signals with all that metal gear we carry and we certainly don't taste good, which is why most attack victims survive the first exploratory nibble, as the shark wrinkles its nose, thinking "eew, human" and goes off to find a tasty seal. If the shark wanted to eat the surfer, we wouldn't be yelling "jeez that surfer got attacked!", we'd be mumbling "I coulda sworn there was a surfer there a minute ago".
I hate printers.
A-law and u-law are used for compression of voice in phones and the like.
True confidence comes not from realising you are as good as your peers, but that your peers are as bad as you are.
So DARPA has developed the AQUEON, http://www.abc.net.au/tv/newinventors/txt/s1106609 .htm , which was actually developed by an Australian in the 70's? Got to make you wonder why no one in our government every checks to see if they are giving out grants for developing stuff that's already been patented. I wonder how much we paid to "develop" something that was probably taken from the original inventor's patent drawings. Sounds like there wasn't much actual development work done, to me. I wonder how big the grant was.
-All that is gold does not glitter - Tolkien
www.ra
Not sure exactly when but I watched an article about this on Tomorrows World a BBC science program sometime between May 1965 and September 1967 (That was the period that my family were based in Northwood. I know it was then because I wanted one and tried to make my own in the workshop that house had).