Ann, watch some of those fish in the big aquarium at your local zoo. There are a few of them that are huge when viewed from the side, and they really do become hard to see when they turn and swim away. My guess is that it is that way to confuse predators.
Rob, sometimes efficiency and streamlining are not the only consideration. Watch some of those fish at the aquarium, some very big fish disappear when they are viewed from the front or the rear. And you don't see very many fish with missile launching abilities.
William is right about shape mattering even more in water than it does in air as far as a fish--or a robot's--speed, maneuverability, and efficiency and therefore power consumption. Just think how much harder it is to swim through water than to walk through air, and the muscles swimming gives your arms as a result.
Rob, shape matters a whole lot in the water and under it, much more than it matters in air. Not only that the greater density takes a lot more power to move it out of the way, but also that the friction of moving through water is greater. One large difference though is that water is generally not compressible,at least not like air.
Altair has released an update of its HyperWorks computer-aided engineering simulation suite that includes new features focusing on four key areas of product design: performance optimization, lightweight design, lead-time reduction, and new technologies.
At IMTS last week, Stratasys introduced two new multi-materials PolyJet 3D printers, plus a new UV-resistant material for its FDM production 3D printers. They can be used in making jigs and fixtures, as well as prototypes and small runs of production parts.
In a line of ultra-futuristic projects, DARPA is developing a brain microchip that will help heal the bodies and minds of soldiers. A final product is far off, but preliminary chips are already being tested.
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