Comments about technological history, system fractures, and human resilience from James R. Chiles, the author of Inviting Disaster: Lessons from the Edge of Technology (HarperBusiness 2001; paperback 2002) and The God Machine: From Boomerangs to Black Hawks, the Story of the Helicopter (Random House, 2007, paperback 2008)

Friday, September 21, 2012

Deep Wrecks: The Battle of Leyte Gulf, 1944

We're coming up on the six-month point following the solo deep-dive of Deepsea Challenger. James Cameron is immersed in movies again and his green submarine has thoroughly vanished from the newsfeeds, presumably to resurface as a 3D movie in late 2012, accompanied by an article about the Mariana Trench in National Geographic. But the adventure must have been fun while it lasted. Along the way I posted info-graphics like this:
Skeptics wondered if anything was behind the big splash in late March other than Cameron's desire to set a solo record and facilitate certain movies, but oceanographic experts were part of the expedition and the Deepsea Challenge project should produce some worthwhile science. I predict most of the value will come from work by the two unmanned landers rather than the manned sub, because the landers could stay down for long periods.

This sidebar question came up among the many articles that dutifully relayed Cameron news that month: What's the deepest shipwreck? Sir Richard Branson said in an interview with the Christian Science Monitor that the oceans has thousands of unexplored wrecks, including galleons: "Magnificent exploration potential," said he.

So that made me wonder what the deepest wreck might be that's still ripe for discovery. I checked with salvage sources and while the question can't be answered with any certainty given the early state of hadal-zone exploration, it's possible to come with a short list of candidates.

Here's my nominee: a Japanese submarine sunk during a battle offshore of Samar Island in October 1944, which was a center of action during the Battle of Leyte Gulf

US Navy records indicate that the destroyer escort Richard M. Rowell sunk a Japanese submarine with depth charges on October 24 at 09 d. 45'N., 126 d. 45'E. For some years war historians reckoned this casualty as I-362, but according to more recent postings on it was I-54, which looked like this:
The sub went down over the Philippine Trench:
That's just west of the Emden Deep's lowest point. This from NOAA's multibeam-sonar bathymetry page:

Other warships hit during the Battle Off Samar could have glided into places as deep that day, but from the battle reports available, I'd vote for I-54 as one of the deepest shipwrecks anywhere, coming to rest at 25,000 to 30,000 feet.

So if Sir R.B. still has lots of money to spend, and if he still wants to go face to face with a hulk never ravaged by treasure-hunters, the Emden Deep would be a good place for Virgin Oceanic to visit.

Saturday, September 8, 2012

A Vortex in Vegas: Advanced fire protection

Last month I was in Las Vegas attending the AUVSI unmanned-vehicle trade show to research an article. While there, I stayed at the Luxor Hotel. It's a pyramid-shaped building with hundreds of rooms arrayed around a cavernous atrium. From the outside, it looks like this:
Those who have walked around the atrium might recall this part of the ground floor near the hotel registration desk and escalator to the theater level. 
Tucked into this scene is a slightly odd structure, about twelve feet high. It looks like a stack of leftover blocks from the Egyptians' last pyramid. 

Here's a closer view. Can you guess why it's there?

Here's another view:
Why would faux limestone blocks have a big hole in a slanted face? Because it's the exhaust port for a very powerful fan. There are eight of them around the base of the atrium (diagram from Fire Protection Engineering, Summer 2000).
Together with other gear (such as smoke-detecting light beams emanating from the obelisk) the "vortex fans" are critical to controlling the movement of smoke in case of fire. 

(That's important because smoke is the principal hazard in most fires, as we know from disasters like the MGM Grand fire in Las Vegas. In that 1980 fire, out of 84 people who died, 82 succumbed to fumes and smoke, rather than flame.)

 Clark County's building department wouldn't have allowed the Luxor Hotel to open without the special arrangements, because standard smoke-handling methods wouldn't work for a giant atrium.

In a traditional building like an office building or an older hotel, each level can be pretty well isolated by careful attention to stairway doors, floor decks, and seals in elevator-lobby doorways. That makes smoke control straightforward: if the barriers hold, smoke can't rise from the fire floor to threaten people on floors above.

The situation is more challenging in tall buildings with cavernous atrium spaces. These have no barriers to smoke movement, so heated smoke can rise, cool and form a toxic, stagnant layer at the top of the space. Why not just install whopping big fans at the apex? It wouldn't be enough to protect guests in the upper levels because a dangerous smoke layer could still form and spread sideways into the rooms. Just raising the apex-fan horsepower would create hazards of its own. 

The solution proposed was this: eight high-capacity fans around the base of the atrium, aimed upward and diagonally, would set the atrium air moving in a vortex. That would confine the smoke into a spiraling column, keeping it away from the floors as it rose toward exhaust fans in the apex.

Clark County wanted a test to verify the computer model, so the hotel owners brought in Hollywood-type smoke generators and gas-fired space heaters to simulate hot smoke from a fire in the base of the atrium.

I'm told the smoke test at the Luxor worked well, with the fans keeping the smoke out of rooms in the upper floors. And kudos to whomever insisted on verifying the model results with a field test! I put little faith in computer models that aren't tested, and retested, against the real world.