Courtesy of Daily Timewaster, we find this beautiful picture of an orca (killer whale) cutting through the water. Note how the liquid flows around its smooth, streamlined body. Click the image for a larger view.
One begins to understand why modern submarine hulls are similarly streamlined.
That's a great photograph. I'd love to know how it was taken: from what sort of platform, how far away, and so on.
Peter
11 comments:
I'd be curious as to how other shapes, like a manta-ray, compare with the conventional designs.
Not very close for mechanical reasons: submarines are pressure vessels and the cylinder is the most efficient shape. They are mostly 1:10 aspect ratio (diameter to length) to reduce overall drag when submerged. For a variety of reasons modern subs are faster submerged than when on the surface.
The exception are the small research vessels who have a spherical passenger compartment with the rest of the craft pretty much free-form.
The last manta-shaped subs I can remember were the minisubs Cousteau had in the 60s and early 70s
The fastest fish have rather different shapes: marlin, sailfish, swordfish. Black marlin can top 80mph, while orca hit about 30.
Atlantic bluefin tuna will do 50 mph. The design on the tunas is so efficient that their gills are placed so that the water flowing out of their gills is laminar over their bodies, instead of turbulent, which would slow them. (I read that pre-internet, so it must be true)
Peter;
Based on 40 years of working in various jobs at Gen Dyn Electric Boat and the fiasco that occurred when American Modeler had an explicit picture of the Seawolf Class submarine on its cover. I would say that photos of this nature were released by the United States Navy Public Information Office. As the U S Navy does not really concentrate on small arms excellence they are known to shoot themselves in the foot with efficient repeatability.
Hmmm... and all these years I'd thought summerines were shaped that way so that when they were made, the asshole didn't snap shut. (USS Simon Lake plankowner, here.)
Based on the Albacore Tuna... :-)
Google image search says this is from the launch of the USS Indiana (SSN-789), taken at Newport News last year. There's a video at https://www.govconwire.com/2017/06/video-indiana-ssn-789-rollout-and-launch/.
Based on the video it looks to me like the shot was taken from the corner of the floating drydock.
Note that something is obscured on the bow, starboard side.
If you'd think clearly about it just a bit, I'd imagine that you would conclude that Peter was talking about wanting to know how the pic of the orca (killer whale) swimming-away was made, NOT the pic of the submarine in dry-dock...
After all - it's pretty self-evidently obvious how the sub was photographed, right? (Duhhh...)
My best guess - in knowing just a small amount about photos of wildlife, and observing the angle from which the orca pic was taken - would be that it was taken from a fairly-small boat that was following directly (and fairly-closely) behind the whale, while traveling at pretty-much the same forward speed, and using a fast, medium-long lens and a high-pixel-count digital camera, or some pretty-high-grade color film stock...quite possibly in video-mode. The smoothness of the water-flow over the body and the wake speaks of either repeated (serial) exposures or continuous image-capture.
Very nice picture, in any event...
If you look at photographs of earlier submarines, from WWII for example, you see that they were designed primarily for surface running. That is because they spent most of their time on the surface. Indeed, they were much faster on the surface than they were submerged.
The advent of nuclear power changed all of that.
The earliest nuclear submarines also had the ship-like hull design as the earlier boats, but because nuclear submarines spend almost all of their time submerged, a new hull design was needed that optimized submerged running. The hull form was known as the "Albacore" hull. Ironically, the USS Albacore, the boat that revolutionized the design and gave the hull form its name, was a diesel-electric submarine named after a type of tuna that influenced the design.
All later boats from the late 50's Skipjack class onward have the "Albacore" hull.
Boats have gotten bigger and longer but the basic hull form has remained the same.
The shape, in both pictures, also reduces flow noise. They can't run away if you sneek up on them.
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