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Comment NumLock off is for remapping! :D (Score 1) 968

I remapped the non-NumLock keypad to the various keys to control my TiVo in SlingPlayer. Zero is the 30-second skip button, the decimal point is back-skip, nine and six page up and down, five and two play and pause, eight is the TiVo button, and SlingPlayer mute and system mute round out the rest.

It's actually quite a nice system (much nicer than Control-F, Control-B, and other seemingly randomly-chosen keys). I use AutoHotKey to set focus to the SlingPlayer window and send the key or keys, so they work regardless of which window had focus. Makes it trivial to skip commercials, but I retain the use of the numeric keypad.

Comment My kingdom for a Newton! (Score 5, Informative) 606

I hate to point you out in Hollywood physics, but I believe you have caught yourself one Newton short of a fig idea there. ;) (Everyone misspeaks once in a while, so I do not begrudge you the error.)

The friendly name you give the force is irrelevant. Calling it "lift", "thrust", or "general uppityness" makes no difference to the physics. There is the force due to the acceleration of gravity on the mass of the aircraft, and there must be an equal and opposite force acting on it in order for there to be no net acceleration. This upward force can only come from an equal and opposite force acting on the air in which the aircraft is hovering.

Obviously, with force being the product of mass and acceleration, you can trade off between those. You can have a relatively small mass of air greatly accelerated in a downward direction, or you could have a relatively large mass of air accelerated less.

For a helicopter, the longer the blades, the more air on which they act, and the less acceleration is therefore necessary in order to yield the same force. To go even more extreme, consider a Harrier. The Harrier has a very narrow column of air *greatly* accelerated to yield the required lift, while a helicopter has a much larger column of air and needs not accelerate it nearly so drastically.

Being impinged upon by the jet blast of a hovering Harrier is certainly going to be more "windy" than being in the rotor wash of an equivalently massive hovering helicopter, but it has nothing to do with "lift" versus "thrust". It has solely to do with the mass of air acted upon and the acceleration thereof.

Comment Re:Harddisks (Score 1) 715

Actually, you hit the nail on the head (or is it nailed the drive on the head?). Everyone's seen those little air holes with the "do not cover" notices, right? Those are, of course, to provide for pressure equalization. So, how does that impact durability?

While the drive is spun up and in use, the heads in your drive do not touch the platters. They float just above the surface on a minuscule layer of air. As ambient pressure is lower the higher your elevation, the number of air molecules available to provide lift to float the heads is reduced. If your elevation is sufficiently high, I can certainly see the potential to impact drive durability.

(Actually, I knew someone who years ago had an IBM Microdrive, i.e. the CompactFlash-sized drives from before flash density was what it later became. He went to use it while up in the mountains one day, well above 10,000 feet, and it quite died. He found out (too late) that it used an air bearing, which truly does not work without sufficient air.)

Hehe, of course, if your elevation were sufficiently high, you could also encounter heat transfer issues (convection is unavailable in a vacuum, after all), but I don't believe that should be most significant for drive durability at elevations at which people generally live.

Communications

Call In the Military To Blast Rogue Satellite? 243

coondoggie submitted a follow-up to the tale of the wandering satellite that might collide with other stuff in orbit. He asks "Will the military need to be called in to blow up the rogue Intelsat satellite meandering through Earth's orbit? Or maybe a NASA Space Shuttle could swing by and grab it? You may recall that in 2008, rather than risk that a large piece of a failing spy satellite would fall on populated areas, the government blasted it out of the sky. The physics of such a shot were complicated and the Navy had a less than 10-second window to hit the satellite as it passed over its ships in the Pacific Ocean. But it worked. Now word comes that a five-year-old Intelsat TV satellite is meandering in orbit and attempts to control it have proven futile. At issue now is that the satellite could smash into other satellites or ramble into other satellite orbits and abscond with their signals."
Hardware Hacking

Home-Built Turing Machine 123

stronghawk writes "The creator of the Nickel-O-Matic is back at it and has now built a Turing Machine from a Parallax Propeller chip-based controller, motors, a dry-erase marker and a non-infinite supply of shiny 35mm leader film. From his FAQ: 'While thinking about Turing machines I found that no one had ever actually built one, at least not one that looked like Turing's original concept (if someone does know of one, please let me know). There have been a few other physical Turing machines like the Logo of Doom, but none were immediately recognizable as Turing machines. As I am always looking for a new challenge, I set out to build what you see here.'"

Comment Aperture is the key, not focal length. (Score 1) 377

Actually, no. As far as telescopes are concerned, focal length is analogous to digital zoom, and aperture is analogous to the camera's sensor resolution. (Telescope resolving capability is a lesson in diffraction-limited optics, which makes an interesting lesson that may be slightly beyond school kids' level.)

You're not interested in how much you can magnify the blurry splotch. You're interested in the details you can or cannot resolve. It's much better to have a small image of the cloud bands on Jupiter than to have a great big image of an out-of-focus tribble.

Comment There is more to music than notes. (Score 1) 560

Much the same as a Beethoven symphony is just a collection of notes and rests, American football is a collection of plays and time between plays. You could, of course, play all the notes in a symphony in one unfettered cacophony, but you would be rather missing the music.

The time between the tackle on one play and the snap which begins the subsequent play is anything but empty. For one obvious example, there are substitutions to attempt to take advantage of the particular circumstances of each play. Other times, the team on offense chooses not to substitute in order to take advantage of the particular defense on the field, and they may even forgo the huddle (in which the plan for the next snap is customarily presented), trading what may have been a better plan for a better opportunity to catch the defense unprepared. The formations used on offense and defense are elaborate set pieces, full of point and counterpoint. Explaining everything that happens between plays would take far more time than we have here, but if you happen to be in Baton Rouge next Sunday, I would be honored to have you over for my small football-viewing event.

A forest is mostly empty space. The trees define it, but that which is between the trees is not insignificant.

It strikes me that the same mentality that drives the "football is boring" whine is just as prevalent in many other situations. I cannot tell you how many times I've heard scuba divers complaining there was "nothing to see" on the very same dive where I found myself utterly fascinated by the quantity and variety of marine life. Unfortunately for this discussion, it is somewhat easier to convince a diver they have overlooked something when you pull up photos of arrow crabs and nudibranchs and so on than it will probably be to convince a "football is boring" person of their misbelief -- for one thing, there are no big fluffy gills sticking out of offensive alignments, even in the red zone.

Comment Forget (e) offtopic, how about (b)? (Score 5, Informative) 560

"[I]t is a violation of the Agreement and this AUP to[...] (b) transmit uninvited communications, data or information"

They don't even say "unwanted" or some such term. According to the letter of their AUP, discovering an old friend's email address (or Facebook page... whatever people use these days) and sending the friend a message "may lead to termination of your Service". They could replace their entire AUP with an at-will statement and it would be no less unconscionable.

Of course, cutting off anyone who sends yet another "e-card" might actually be justified, and according to AUP 2.b, they could do it. :)

Obviously, it's not likely they will enforce the AUP in an egregiously Draconian manner, but I for one would prefer having the outlandish bits *implied* rather than expressly stated. It just looks cleaner. On the other hand, they didn't quite go completely Pythonesque on us:

Prohibited:
1. Users named other than "Thomas".
2. Users named "Thomas".

Comment Wow, it's my TRS-80 Color Computer 2! (Score 4, Insightful) 166

My very first computer was a TRS-80 Color Computer 2. It was basically a computer in a keyboard that I connected to the TV. Now, decades later, I will soon be able to buy a computer built into a keyboard that will display on my TV.

"What has been will be again, what has been done will be done again; there is nothing new under the sun." Ecclesiastes 1:9 (NIV)

Of course, if this can handle "HD" YouTube, Netflix streaming, and other online sources, it might actually be worth looking into as an alternative to building my own low-power box for the TV. At least worth keeping an eye open, I suppose.

Comment Re:And what do you know, I *do* have a point. (Score 2, Informative) 83

Which, given the fact that fairings don't particularly represent a difficult design or development problem, indicates that something (major) is wrong at SpaceX.

So, you're saying that fairings are, to use the phrase, "not rocket science"? It's certainly true that a fairing design and implementation is not nearly as difficult a nut to crack as designing a new liquid-fueled engine completely from scratch, but fairings and fairing separations aren't something so inherently mundane that they can be ignored.

The aerodynamics are not so trivial you can just say, "Eh, that looks about right..." and be at an energy-optimal solution. Additionally, while it's trivial to overbuild a solution that will protect the payload during ascent, reducing the mass of the fairing system is not so easy. (Like most things in engineering, the first bits are easy, with additional improvements coming with greater and greater effort.) Having additional time to shave off a few more kilograms from the fairing is certainly a net positive.

Now, as for fairing separation incidents, there have not been many, but a quick check does turn up three of note in the last decade or so:

I cannot speak to the failure potential of a new fairing design on a new launch vehicle as compared to existing fairings on well-traveled vehicles, but if I were to go with a "feeling", I would certainly doubt that it is less.

(By the way, your ad hominem song and dance routine was hardly mature. Will you be coming to Geowoodstock next year up in your area? I'm thinking of possibly heading up for the event and some cold water diving next year, and I wouldn't mind betting a batch of my homemade chocolate chip cookies on SpaceX -- perhaps you can bet a family-restaurant-level dinner? I don't drink, so it shouldn't be expensive.)

Comment And what do you know, I *do* have a point. (Score 1) 83

"This gives us the best flight data in advance of our first COTS mission," Musk said. "It also removes the (payload) fairing from the schedule critical path and allows us to spend more time on making the fairing lighter and more reliable."

Source: SpaceX doubles down on inaugural Falcon 9 mission

Comment A payload would require the fairing, too... (Score 1) 83

This sounds more like, after the debacle the Falcon I has been to date, nobody is willing to risk their payload even for the reduced prices (sometimes even free) that such launches usually charge.

Actually, the situation is that there are two complementary reasons in play. By using the static test Dragon capsule, they get valuable engineering data about the dynamics of the integrated system that they can use to make any adjustments in advance of the first Dragon COTS launch.

The other factor influencing the decision is that the Falcon 9/Dragon configuration does not use the payload fairing. By using the static test Dragon capsule for the Falcon 9 demo launch, they can extend development of the payload fairing without impacting the demo launch time line.

Not requiring a finalized Falcon 9 payload fairing until flight five gives them significant additional time to optimize the fairing. Acquiring valuable flight test data by using their already-built static test Dragon capsule just makes it the proverbial "win-win" situation.

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