Virtual Earth Exposes Nuclear Sub's Secret

NewsCloud alerts us to a story a few months old that has been getting a lot of play recently. A Seattle blogger, Dan Twohig, was browsing in Microsoft's Virtual Earth when he accidentally came across a photo of a nuclear sub in dry-dock. Its propeller is clearly visible — this was a major no-no on the part of someone at the Bangor Sub Base. The designs of such stealth propellers have been secret for decades. Twohig blogged about the find and linked to the Virtual Earth photo on July 2. The debate about security vs. Net-accessible aerial photography has been building ever since. The story was picked up on military.china.com on Aug. 17 — poetic justice for the Chinese sub photo that had embarrassed them a month before. On Aug. 20 the Navy Times published the article that most mainstream media have picked up in their more recent coverage. Twohig's blog is the best source to follow the ongoing debate. No one has asked Microsoft, Google, or anyone else to blur the photo in question. Kind of late now.

Comments

Re:Probably not significant

[srmalloy]

Looking at the picture, the screw on the boat looks remarkably like the designs from a couple of decades ago for high-efficiency, low-noise propellers for aircraft, where the blades wrapped backwards around the engine nacelle. The problem with aviation propellers is that to get more power, you can make the prop bigger in diameter, but eventually the tip speed reaches the speed of sound, which causes a huge increase in noise, vibration, and wear; a skewback propeller increases the driving surface while allowing the rotation speed of the prop to stay lower. The situation is just as important for submarine propellors, where the higher velocity of the outer edge of the screw will cause it to cavitate at a lower number of revolutions than the inner part, so you want to put more driving surface inside the critical diameter for the number of revolutions you expect to be making at cruising speeds.

Mii No comprende but you for real!

[Krozy]

I have no idea what any of that means in real life, but it sounds enough like Tom Clancy writing that it must be true! Words like 'skewback', 'nacelle', 'cavitate' sound s-m-art.