Slashdot Mirror


User: ClayJar

ClayJar's activity in the archive.

Stories
0
Comments
214
First seen
Last seen
Profile
(view on slashdot.org)

Comments · 214

  1. Too soon losing Roblimo, but the post seems strangely appropriate.

    RIP Roblimo

  2. "At an airport" meaning Class B airspace. on The FAA Gave the First Ever Go-Ahead For a Drone To Fly at an Airport (recode.net) · · Score: 4, Informative

    The subheading in the linked article ("It's the first waiver granted for flight in Class B airspace since the FAA came up with commercial drone rules.") makes sense, but the summary, title, and article are a bit wonky.

    It's been perfectly legal for a certified commercial Remote Pilot to fly at an airport since Part 103 went into effect, but only in Class G airspace. Small airports with Class E Surface or Class D airspace would require a waiver, and waivers have been had for those for a while now. Larger airports with Class C airspace took longer before the FAA began processing (and approving) waivers, but there had not been any waivers of Class B airspace. This is the first.

    Of course, you can only get a waiver under Part 103, so if you're a hobby pilot, the five-mile rule is in effect. For Part 103 Remote Pilots, on the other hand, it's all about airspace. (Most of the FAA Knowledge Exam is airspace and weather.)

  3. Re:All Electric? Cool! on SpaceX's Falcon 9 Crashes Into Droneship (cbsnews.com) · · Score: 5, Informative

    Also, chemical propellant is "heavy", meaning it takes much more mass to get an equivalent kick. If you want real words, the Isp (specific impulse) is lower for chemical propellant engines than for ion engines. With all electric satellites, you can carry much less propellant, meaning you can have a satellite of comparable capability in much less mass. In the case of these two satellites, the Boeing BSS-702SP platform they're built on means you can fit two on a "normal" GTO launch. That basically halves your launch costs.

    The tradeoffs are that while all electric propulsion is very "fuel efficient", the thrust of ion engines is a very small fraction of that of the more conventional chemical propellant engines, so instead of taking days to settle in to your final orbit, it can take weeks of slow orbit raising. This is a "cost" that may or may not be worth the trade. Also, since the 702SP satellites are launched in pairs, a launch failure could take out two birds with one... rocket. To give a bit of insurance against this, Eutelsat and ABS chose to split two rockets. They'd each fly one satellite per launch, meaning they only risked one of their two each flight in case of a Very Bad Day.

  4. Don't forget IBM PCjr! on Microsoft Patents A Modular PC With Stackable Components (venturebeat.com) · · Score: 1

    I never had one, but a friend whose dad worked for IBM did, complete with a whole stack of sidecar expansions. It actually looked rather entertaining as wide as it ended up.

    Admittedly, they stacked to the side and were only for expansion, but they did stack (or daisy chain, if you use more mellifluous terminology).

  5. Re:No KSP at SpaceX? on SpaceX Rocket Launch Succeeds, But Landing Test Doesn't · · Score: 1

    The SRBs from Shuttle launches were indeed reused... after a fashion. Each booster was four segments. After each flight and recovery, the boosters were disassembled and the segments renovated and reloaded. The segments were not kept together as a set, so each SRB used in a launch would have four segments each with their own history. (This was expressly noted on NASA TV during each launch, with comments about the oldest and newest segments on the flight and so on.)

    As for SpaceX, early Falcon 9 flights had parachutes on the first stage, but the stages did not survive reentry (much less make it all the way to landing). Since you can not land anything large on Mars with parachutes, SpaceX would have eventually had to work on hypersonic retropropulsion, propulsive landings, and so on; they merely pivoted away from the parachute "dead end" and went straight to propulsive recovery with Falcon 9 v1.1.

  6. Re:Shooting themselves in the foot on Elon Musk Addresses New Jersey's Tesla Store Ban · · Score: 1

    "Our stores will transition to being galleries, where you can see the car and ask questions of our staff, but we will not be able to discuss price or complete a sale in the store. However, that can still be done at our Manhattan store just over the river in Chelsea or our King of Prussia store near Philadelphia."

    Sales over the border? Already ready. Collecting tax revenue? If NJ is anything like my state, they'll collect that when you register the vehicle in NJ. The state isn't going to be out much money, but the dealers are protected by the politicians who get their campaign contributions, and neither has to give a hoot about inconveniencing the people. (The people inconvenienced weren't going to buy from the dealers, so no money lost there, and they aren't numerous enough to make a dent in the elections, so that's all fine and dandy, too.)

  7. Re:Won't they hit the ISS on a future orbit? on ISS Astronauts Fire-Up Awesome 'Cubesat Cannon' · · Score: 5, Informative

    They're launched from the nadir side in a nadir-aft 45-degree direction to prevent collision with the ISS. That imparts a small negative delta-V (with insertion velocity between 1.1 and 1.7 m/s), so their orbit would begin just slightly below the ISS. Additionally, one of the requirements for CubeSats launched from J-SSOD is that they have a ballistic coefficient of 120 kg/m^2 or less. This means that their orbits will decay faster than the ISS orbit, precluding any potential for collisions over time.

    (The life expectancy on orbit of a CubeSat launched from J-SSOD is something like 100-150 days, depending on orbital parameters as of deployment, solar activity, etc.)

  8. Can we please make it narrower? on Come Try Out Slashdot's New Design (In Beta) · · Score: 5, Funny

    I'm *so* tired of having slashdot use the entire width of my browser. I've been pining for expansive areas of whitespace for years!

  9. The first stage is suborbital. on The Grasshopper Can Fly Sideways · · Score: 5, Interesting

    Heat shields are the efficient way to slow from orbital speeds for reentry (e.g. the Shuttle), but conveniently for recovery the first stage isn't orbital. Grasshopper is basically a modified Falcon 9 first stage, and the goal of the testing is recovery of the first stage of Falcon 9-R, which is much easier than reentry from orbit..

    We're not talking single stage to orbit here, and recovery of the second stage would certainly involve a heat shield. The first stage is a different animal. SpaceX seems to be intending to use a boost-back trajectory concept. I look forward to seeing how that works. (The controlled water "landing" attempt will be something to see, too, of course.)

  10. The Last Paper (in free verse) on Gubernatorial Candidate Speaks Out Against CAS · · Score: 1

    They wrote a story

    typeset in the form of a seventh-grade paper

    where only the page count matters.

    But the trick never worked

    as the teacher docked them anyway.

    It was worth one more try.

  11. Leatherman killed the tool market. on Will Tablets Kill Off e-Readers? · · Score: 5, Funny

    Leatherman killed the tool market when it came out. Why buy a single-purpose tool when you can get many more features for a little bit more money?

    Sometimes having something that *doesn't* slice, dice, and julienne fries is the better choice. I mean, sure, I could do many small repairs using just a leatherman, but a nice set of wrenches and drivers makes working on my bike *much* nicer. Or how about crescent wrenches (or shifting spanners, as the case may be)? You can handle all variety of nuts, bolts, and fittings. SAE, metric, square, hex? All are open to you. Yet anyone who spends much time working on mechanical things knows that a crescent wrench, while convenient, is often vastly inferior to a good set of wrenches.

    When I'm out on a ride, I carry a small multitool that *does* do a bunch of things in one small, inexpensive, unobtrusive package, just as when I'm out and about, I can get some reading done on my Nexus 7. The Nexus 7 is convenient, but if I ever broke my e-ink Kindle, I'd have a replacement ordered that very day. E-ink readers are basically designed to fill the niche of "electronic trade paperback for avid readers". They fill that niche exceedingly well, and avid readers are a renewable resource.

  12. Awkward... on Why The Hobbit's 48fps Is a Good Thing · · Score: 5, Interesting

    Actually, I was thinking more along the lines of the Hogfather (specifically from the movie).

    While I enjoyed this first Hobbit movie, I found the Radagast scenes awkward (like an old family photo with too-large glasses and sisters with poofy bangs). Radagast and his bunny sled seemed too much like something right out of Discworld, which would be delightful except that combining Discworld and Middle Earth yields a very large impedance mismatch.

  13. Re:A tsunami in deep water is a non-event. on Nearly 150 Companies Show Interest in the Tech Love Boat · · Score: 1

    You are correct. A ship can take much larger waves directly into the bow than it can take abeam. It's perfectly logical if you think about it. The bow is designed to plow into the water, so it'll deflect the wave energy better, and designers know storms will come, so they design to some extent or another for waves breaking over the bow. Waves running directly into the side have a large surface to work on.

    Additionally, consider the simple geometry. A ship is going to be much more stable in the pitch axis (where it is a nice, long lever) than in the roll axis (where it's much closer to a round log). Tipping a ship end-over-end would require something more like a Michael Bay movie, while capsizing it by rolling it over requires much less force.

    The images I've seen of this ship show something much more like a floating rig platform than a plain old large yacht. It has a long axis, but it's much wider than a "normal" ship. That being the case, it would have more stability in the long axis, but it should be stable enough in the short axis. You *could* just go ahead and build a platform instead of a ship, with deep ballasts well below wave action attached by legs to the main platform well above the waves, but that expense, inconvenience of access, and greatly reduced mobility is apparently undesirable.

  14. A tsunami in deep water is a non-event. on Nearly 150 Companies Show Interest in the Tech Love Boat · · Score: 2

    Off-shore in deep water, there is absolutely no danger whatsoever from a tsunami. A tsunami is only a problem as it reaches shore, as it's there that the very long period waves just keep coming and coming and piling up water. In deep water, there's just a very, very long swell of minuscule amplitude.

    Storm waves are vastly more significant. Their period is short enough and their amplitude great enough to potentially cause significant damage to oceangoing vessels. Considering also the occasional rogue wave (a wave or short set of waves at several times the amplitude of the prevailing wave conditions at the time), and having lifeboat/evacuation drills every so often would be best practice. At least the area in question is outside the hurricane belt, so hurricane evacuations (such as those from Gulf of Mexico oil rigs) shouldn't be required.

  15. Re:Launch window on SpaceX Launch To International Space Station Delayed For Code Tweaks · · Score: 1

    The Space Shuttle had a launch window of approximately plus or minus five minutes from in-plane, but for the Falcon 9/Dragon COTS-2/3 launch to ISS, they have an instantaneous launch window. From the comments on the COTS-1 webcast, it sounded as if Dragon flights to ISS would have instantaneous launch windows, but I have no data to know whether this is merely a constraint for the initial flights or a constraint for all future COTS/CRS launches.

    For the April 30th window (which will not be used), there was also an instantaneous launch window on May 3rd (with the days between those two blocked by ISS orbital constraints, I believe -- SpaceX has additional requirements for the test launch and recovery than for an operational launch). The next set of instantaneous launch windows would be May 7th and May 10th (with the days between blocked), but the May 10th window would mean that in the event of an aborted docking, there would be only time for one additional attempt before Soyuz conflicts (which would push the Dragon docking beyond May 17th, which may or may not be possible depending on fuel constraints, which I am not privy to).

    Regarding the failure probabilities, from last week's press conference, it sounded as if SpaceX is the primary driver of mission assurance for this flight, i.e. they want to be sure they have as many of their waterfowl properly queued as possible. A cynic might note that if they don't get it right this time, it costs NASA nothing and SpaceX the full cost of another attempt. Someone with a brighter outlook would likely just say that if *everyone* on earth were watching you (most hoping you'd succeed, some hoping you'd fail), you'd *really* want to double-check everything one last time.

  16. Cox Communications on Failures Mark First National Test of Emergency Alert System · · Score: 5, Informative

    I was watching the test on a friend's Cox Communications cable service, and they also switch to a shopping channel (cable channel 8) for emergency alert activations. Their cable system apparently is incapable of showing the alert on all the (digital?) channels, so they simply show it over analog shopping channel 8 and have a system in place to switch everyone to that channel automatically whenever an alert is triggered. It's a bit annoying if a test is scheduled during, say, an important football game... er... episode of Mythbusters... whatever. On the other hand, it is even more jarring than the alert tones, so you'll certainly know something's afoot.

    If you have one of their Motorola digital cable boxes, when it goes into emergency alert mode and auto-switches to analog shopping channel 8 for the message, the front clock display changes to "EAS" as well. If you're suddenly watching the shopping channel and "EAS" is displayed on the cable box *and* you have the wonderfully annoying (and intentionally so) alert tones, you *should* be able to figure out that now's the time to read or listen. At least, that seems to be the general idea.

    I did notice that I didn't get the alert over cable until after I'd finished watching it on OTA TV (and chatting about it afterward), so chalk up a minute or two of additional latency to the cable company.

  17. Random is trivial, as the TEDx Talk explained. on Mathematically Pattern-Free Music · · Score: 2

    Actually, as was explained in detail in the video, random is easy. Completely devoid of repetition is vastly more difficult. This was not simply random, this was mathematically non-repetitive. Using random numbers outside of the audible range would not necessarily preclude repetition, and using random frequencies is atonal sound, not tonal non-repetitive "music" as was the intention of the piece.

    Completely random is trivial. Mathematically-sound aperiodic and repetition-free is a completely different kettle o' fish.

    Note that the composition used the 88-tone chromatic scale of the standard piano keyboard. Without that constraint, you could make a much longer atonal composition, of course, but the point of the exercise was to use discrete mathematics and music to create a tonal composition completely devoid of repetition.

  18. There are FOUR lights! on Security Researchers Crack APCO P25 Encryption · · Score: 1

    I was afraid you were going to tell me there were five researchers, but you don't even *look* Cardassian.

  19. Dibs on the nickname! on Germany Builds Encrypted, Identity-Confirmed Email · · Score: 1

    From the sound of it, it'll almost inevitably end up costing money. With that in mind and by the powers vested in me by absolutely nobody in particular, I hereby dub it "feemail".

    (One *could* say that it is supposed to be a kinder, more respectable alternative to the rough-and-tumble wild west of existing (e)mail, but then there are those who think it's just a prettier version that will inevitably cost a bunch of money.)

  20. NumLock off is for remapping! :D on Google Wants To Take Away Your Capslock Key · · Score: 1

    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.

  21. The closing is almost as sweet. on FBI Instructs Wikipedia To Drop FBI Seal · · Score: 1

    Although it is not quite as colorful, I personally loved the closing: "With all appropriate respect,"

    Now that, dear friends, is irony.

  22. Aperture is the key, not focal length. on What Objects To Focus On For School Astronomy? · · Score: 1

    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.

  23. There is more to music than notes. on Will Your Super Bowl Party Anger the Copyright Gods? · · Score: 1

    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.

  24. Forget (e) offtopic, how about (b)? on Verizon Changes FiOS AUP, -1, Offtopic · · Score: 5, Informative

    "[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".

  25. Re:Heh, simple. Don't update. on Microsoft Investigates Windows 7 "Black Screen of Death" · · Score: 5, Funny

    Securing windows is like pushing water uphill with a sharp stick.

    So, if I follow what you're saying, securing windows is much easier when it freezes?