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Comment: Re:140000 Newton (Score 2, Informative) 153

by ikeleib (#27127755) Attached to: Europe's Biggest Amateur Rocket Completes Test-Firing

Saturn V was a 'multi-gear' rocket. To lift off the pad, all 5 main rockets fired. As altitude increased, the center rocket turned off to minimize stress on the rocket (stay subsonic???)

Space shuttle also has multiple speeds. If you remember the Challenger disaster - the last message from ground was "Go with throttle up" Apparently the shuttle was high enough to go full throttle (again) and not worry about aerodynamic stresses.

Most liquid fueled rockets are throttleable. Both the space shuttle and Saturn V's throttle down to avoid putting "too much stress" on the airframe. What this really means, is that they didn't want to put more weight into airframe structure, and instead reduce throttle to the point where the atmosphere thins enough that one can throttle up without surpassing the design strength of the airframe. By the way, this point is called Max-Q and for the space shuttle, it is at 11km in altitude. For the space shuttle main engines, this means they throttle up to 104% of specification power (due to improvements over the years, the SSME maximum safe throttle is actually 109% of specification).

One of the issues with the shuttles solid rocket boosters - they are steerable - allowing insertion into a very precise orbit.

Compare that with the typical home built - solid rocket, that basically goes were you point it...usually...give or take a bit.

The problem with solid rocket motors for space travel is two fold. The first is that they cannot be throttled or turned off. The second is that they are considerably less efficient pound-for-pound than liquid fueled rockets. The typical measure of rocket efficiency is specific impulse, which is measured in seconds. For example, the solid rocket boosters of the shuttle have a specific impulse of 242 seconds, while the space shuttle main engines produce a specific impulse of 363.

Power

+ - Thin Clients: Eco-Friendly Alternative to PCs->

Submitted by
mrcgran
mrcgran writes "This report is month-old, but still interesting: 'Using thin clients instead of conventional PCs would lower energy consumption by 51 percent and reduce CO2 emissions, concludes a recent study by the Fraunhofer Institute. The study compared thin clients to conventional business PCs. "The financial savings are significant but the impact on cutting CO2 emissions is what's really impressive. Saving 2.45 billion pounds of CO2 emissions would remove the equivalent impact of 106,521 average U.S. households each year."' Lots of Linux thin clients are springing up. Would you replace your conventional PC for one of them?"
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Databases

+ - LiquiBase Database Refactoring 1.0->

Submitted by
nvoxland
nvoxland writes "After over a year of active development, LiquiBase 1.0 has been released. LiquiBase is a java-based, LGPL, DBMS-independent library for tracking, managing and applying database changes. It is similar to Rail's Active Migrations, but doesn't suffer from the same problems with multiple developers and branches. It also has many unique features such as 30 refactorings, rollback support, and upgrade script SQL-generation."
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Spam

+ - Spam: now available in PDF->

Submitted by
choongiri
choongiri writes "If my inbox is anything to go by, there's a new breed of spam on the loose. Last year saw the rise of the image-based penny stock spam — that got around our filters for a while until tools like the FuzzyOCR plugin for SpamAssassin came along. Now it looks like the spammers are taking it to the next level, attaching their spam content as a PDF file. No doubt if this persists we'll see PDF scanning becoming standard practice, although the cost — both in bandwidth and CPU cycles required to do the filtering — will certainly be non-trivial."
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Programming

+ - No iPhone SDK Means No iPhone Killer Apps->

Submitted by iPhoneLover/Hater
iPhoneLover/Hater (666) writes "Gizmodo is running an article analyzing the potential failure of the iPhone as a truly revolutionary platform. The reason: no SDK to harness the true power of Mac OS X and the frameworks contained in Apple's smart cell. From the article: "According to Apple, "no software developer kit is required for the iPhone." However, the truth is that the lack of an SDK means that there won't be a killer application for the iPhone. It also means the iPhone's potential as an amazing computing and communication platform will never be realized. And because of this and no matter how Apple tries to sell it, the iPhone won't make a revolution happen.""
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Portables

+ - Asus Eee PC Hands-On, Competition For The OLPC

Submitted by MojoKid
MojoKid (1002251) writes "Asus made quite a splash at the Computex show last week with the introduction of their Eee PC, a low cost, highly portable machine slated to compete with the OLPC project. At price points of $199 and $299 for 4GB and 8GB Solid State Flash drive equipped models, the Asus Eee PC looks to be formidable. This exclusive first-ever hands-on showcase of the machine shows the two interfaces of its Linux-based operating system as well as its modes of operation, pre-installed open source Office software and other applications like Skype. The ASUS Eee PC will be available world wide, in full production quantities in Q3 this year. It is rumored to have a street date of mid August."
Bug

Apple Safari On Windows Broken On First Day 595

Posted by kdawson
from the bigger-they-come dept.
An anonymous reader writes "David Maynor, infamous for the Apple Wi-Fi hack, has discovered bugs in the Windows version of Safari mere hours after it was released. He notes in the blog that his company does not report vulnerabilities to Apple. His claimed catch for 'an afternoon of idle futzing': 4 DoS bugs and 2 remote execution vulnerabilities." Separately, within 2 hours Thor Larholm found a URL protocol handler command injection vulnerability that allows remote command execution.
United States

+ - Lifting H-1B Caps Heralds 'In-Sourcing' Surge

Submitted by Anonymous Coward
An anonymous reader writes "'In-Sourcing' is the name for new scourge of the American high-tech worker, argues InformationWeek blogger Alexander Wolfe. He's coined that term in response to the call from Google, Bill Gates, and other captains of tech industry to lift the current cap of 65,000 H-1B visas, which allow foreign nationals to fill U.S. tech jobs when companies claim they can't find qualified domestic workers. Writes Wolfe:"Having winnowed the domestic pool of highly experienced IT and engineering talent by hounding thousands out of the business through years of layoffs and false complaints about the math-smarts of American students, big business has hit on the latest tack for controlling high-tech labor costs: In-source the jobs it was previously outsourcing, by getting the government to lift the cap on H1-B visas." But he says he doesn't blame Google; he blames Bill Gates, and NY Times columnist Tom Friedman, who claims there's been a steady erosion of science education in U.S. schools. "What engineering school did Friedman attend?" Wolfe asks. Do you agree that this "crisis" is hurting the U.S. tech community, or is there a legitimate shortage?"
Portables

+ - Asus and Intel challenge OLPC with Eee PC->

Submitted by
fl!ptop
fl!ptop writes "George Ou at ZDNet says, "The user interface of the OLPC doesn't even feel worth of a cheap fisher price toy" but raves about a new Asus/Intel super cheap UMPC. "The ASUS Eee computer will cost a mere $199 for the 7" LCD model whereas the so-called $100 OLPC costs $175. Given the fact that Eee can run Linux or Windows XP and it can boot off NAND flash memory in a mere 15 seconds, the Eee slaughters the OLPC with ease." C|Net has some more information on the Eee PC when it was introduced at Computex last month in Taiwan."
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Technology (Apple)

+ - ZFS To Become Default File System In Leopard->

Submitted by Anonymous Coward
An anonymous reader writes "Posted on macrumors.com:
Perhaps overcome with excitement (and forgetting that Apple doesn't like such pre-emptive disclosures), Sun's Jonathan Schwartz announced today at Sun event in Washington D.C. that Apple would be making ZFS "the file system" in Mac OS 10.5 Leopard (video link, requires RealPlayer).

Quote: In fact, this week you'll see that Apple is announcing at their Worldwide Developer Conference that ZFS has become the file system in Mac OS 10. Rumors of Apple's interest in ZFS began in April 2006, when an OpenSolaris mailing list revealed that Apple had contacted Sun regarding porting ZFS to OS 10. The file system later began making appearances in Leopard builds."

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