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Comment: Re:Updating gman003's post (Score 4, Interesting) 32

Apollo 13 should count, but not for what most people know about.

The second stage center engine shut down early due to a thrust chamber sensor reading low pressure. While this did not impact the orbital insertion (the remaining 4 engines fired for an additional 4 minutes to make up for it), the sensor reading that shutdown the engine may have been in error, and is still not understood. However, if this shutdown had not occurred, the vehicle would likely have been lost in just moments after when the shutdown occurred. The center engine was experiencing severe pogo osculations, resulting in the engine flexing the thrust frame up and down by 3 inches, 16 times each second—this motion would have resulted in disintegration of the rocket in short order. The thrust chamber sensor should have been unaffected by the pogo, so that is unlikely to be the cause of the reading that led to the shutdown. So it is possible that while one failure during launch almost destroyed Apollo 13, a second failure actually (temporarily at least) saved the mission.

See this article for more information.

Comment: Re:Really bad idea. (Score 1) 1173

by Granular (#36653986) Attached to: Roundabout Revolution Sweeping US

Roundabouts (or rotaries, or traffic circles, as they're known in parts of the U.S.)

This is part of the problem with the perception of roundabouts in the US: people don't know what is and what is not a roundabout. The modern roundabout came about in the UK in the late 70's and early 80's, and is a small (typically <200' diameter, depending on the number of lanes) circular intersection where the entering traffic yields the right of way to circulating vehicles. In multi-lane roundabouts, lane changes within the roundabout are not permitted.

Rotaries and traffic circles have been present in the US for the past 100 years (and are much more common on the east cost than elsewhere). These can be up to 1000' in diameter, and have varying traffic control (from circulating vehicles yielding to entering vehicles, to traffic signals at the approaches or crosswalks). Speeds at rotaries and traffic circles can also be quite high, and lane changes and merging are often permitted.

The main difference is that the modern roundabout is designed to keep traffic speeds low (ideally around 15mph, but usually less than 25 mph), and are often empirically designed (this varies from state to state, many use empirical models, but some use gap acceptance theory) based upon driver behavior.

But I loathe rotaries when there's a lot of traffic. You can sit there for a lot longer than you would at a red light.

Roundabouts are not indented for extremely high traffic volumes, or in close proximity to signalized intersections, as the platooning vehicles from the adjacent signals will disrupt the flow of traffic through the roundabout. If you are stopped and waiting at modern roundabout, unless the traffic condition is extremely uncommon for the location, the roundabout was either designed improperly, or was ill-considered for the location. If you are not in fact at a modern roundabout, but at an old-style rotary or traffic circle, then the FSM only knows what is happening.

And, BTW, I am a highway engineer, so take this as you may.


Dead Goldfish Offered The Vote In Illinois 216

Posted by samzenpus
from the Mr.-Limpet dept.
Election officials in northern Chicago want to know why voter registration material was sent to Princess, a dead goldfish. "I am just stunned at the level of people compromising the integrity of the voting process," said Lake County Clerk Willard Helander, a Republican, who said she has spotted problems with nearly 1,000 voter registrations this year. Beth Nudelman, who owned Princess, said the fish may have got on a mailing list because the family once filled in her name when they got a second phone line for a computer. When will we recognize a goldfish's right to vote?

It is much easier to suggest solutions when you know nothing about the problem.