John Walker

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 15 hours, 34 minutes ago

    CONTINUITY

    “Rails Thermite Welding – Eruptions, Melt Squeezing and Grinding”

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 17 hours, 38 minutes ago

    CONTEXT

    “Surprise Signature”

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 1 day, 6 hours ago

    THE HAPPENING WORLD

    “Virgin Orbit’s LauncherOne failed to reach orbit in its first launch attempt Monday”

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 1 day, 11 hours ago

    TRACKING WITH CLOSEUPS

    “HP Switching Power Supply Repair Part 2: Debugging the Startup Circuitry”

    The power supply repair saga continues, tracking the problem back into the start-up bootstrap circuitry and chasing a confounding instrumentation problem.

  • John Walker posted an update in the group Group logo of Reading ListReading List 1 day, 11 hours ago

    Schlichter, Kurt. Indian Country. El Segundo, CA: Kurt Schlichter, 2017. ISBN 978-0-9884029-6-6.

    In his 2016 novel People’s Republic, the author describes North America in the early 2030s, a decade after the present Cold Civil War turned hot and the United States split into the People’s Republic of North America (PRNA) on the coasts and the upper Midwest, with the rest continuing to call itself the United States. This book, the second to feature Turnbull, is a “prequel” set shortly after the split, which was along the borders of the existing states. This left regions whose nat…[Read more]

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 1 day, 11 hours ago

    CONTEXT

    “Which Is the Strongest Steel Bridge Design? Hydraulic Press Test!”

    Testing viewer-submitted bridge designs, all of which use a standard roadway. Ranking is by yield force over mass of bridge.

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 1 day, 17 hours ago

    TRACKING WITH CLOSEUPS

    “Pakistan International Airlines #8303 Runway Evidence —
    Update #3”

    Scrape marks on the runway indicate the engines contacted the runway three separate times. Touchdown was far beyond the normal landing point on the runway.

    • My guess is that Airbus used the same Indian software vendor that Boeing did for the 737 Max. The generic warning chime caused by attempting to lower the gear at too high a speed disabled the “too low gear” warning that should have kicked in thereafter.

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    • Juan Brown has been bang-on about this one.

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  • John Walker posted a new activity comment 2 days, 5 hours ago

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 2 days, 8 hours ago

    THE HAPPENING WORLD

    “Crew Dragon Launch Day Timeline: From Suit Up to Docking with the ISS”

    Preview of events on launch day of the Crew Dragon mission to the ISS.

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 2 days, 9 hours ago

    CONTINUITY

    “Laying of Western Union Trans-Atlantic Telegraph Cable 1928”

    From the original Roaring Twenties: laying of a trans-Atlantic cable to carry teletype traffic between Newfoundland and the Azores.

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 2 days, 9 hours ago

    CONTEXT

    “Lock Picking an Outside Tap Faucet and Taking It to Bits”

    Starts with a good example of picking a not-very-secure lock.

  • John Walker posted a new activity comment 2 days, 13 hours ago

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 2 days, 17 hours ago

    CONTINUITY

    “HP Switching Power Supply Repair Part 1: How It Works”

    Reverse-engineering and repairing a blown-up switching power supply from a 1990s Hewlett-Packard instrument. This is the “new H-P”: “too new to provide a schematic; too old to repair”. This is the first part of a multi-part series.

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 2 days, 18 hours ago

    TRACKING WITH CLOSEUPS

    “Why Did NASA’s Head of Human Spaceflight Resign Just before Historic Launch?”

    Was there some funny business (possibly involving Boeing, who was not selected) in the procurement of human lunar lander candidates for the Artemis project?

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 3 days, 8 hours ago

    CONTEXT

    “Pakistan Airlines #8303 Update”

    More information on the accessory gearbox on the CFM56 engines which may have failed after contact with the runway, leading to loss of power that resulted in the crash. Why the crew proceeded to touchdown after an indication of failure to lower the landing gear remains a mystery.

  • John Walker posted a new activity comment 3 days, 8 hours ago

    >> Is the Wiki article on “Horizontal Integration Facility” something I should maybe trust?

    Yes, that describes facilities for assembling rockets and payloads horizontally. The U.S. traditionally used vertical integration (stacking) because it allowed lighter rocket stages which couldn’t take the stress of being erected to vertical before launch. Horizontal integration saves money since most of the work can be done close to ground level without the need for scaffolding or a means to work on the rocket on the pad or to transport it vertically from the assembly facility to the pad…[Read more]

  • John Walker posted an update in the group Group logo of UpdatesUpdates 3 days, 10 hours ago

    2020 May 23

    Updated the WP-UserOnline plug-in to version 2.87.5.  This is a
    completely trivial update which simply adds some bots to the
    table of known bots.  The release notes claim they update the
    WordPress compatibility claim to 5.4, but in fact they forgot to
    do that in the code.  We have no local code in this plug-in. I
    syntax checked the modified files and applied the update kit.
    Everything looks OK.
    

    Committed the WP-UserOnline plug-in version 2.87.5 update (Build 270) and published to GitHub.
  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 3 days, 12 hours ago

    CONTINUITY

    “Pulse Oximeters: an Amazing Use of Light”

    Measuring the oxygenation of blood without puncturing the skin. How do they do it?

    • I have several. The covid pandemic has caused a run, with prices doubling. There are the instant readers like he had and there are logging/tracking meters (typically used for monitoring levels during sleep to monitor sleep apnea, etc.). Do a web search (without quotes) for “oximeter ring” or “wearable oximeter”.

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  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 3 days, 16 hours ago

    CONTEXT

    “Why We May Be the Only Intelligent Life in the Universe”

    Hour-long interview with exoplanet researcher David Kipping, author of a paper where he presents a Bayesian analysis of the probability of life developing on other planets and moons and of the emergence of complex life and intelligence.

  • John Walker posted an update in the group Group logo of SCANALYZERSCANALYZER 3 days, 19 hours ago

    THE HAPPENING WORLD

    This is the first horizontally-integrated U.S. crewed spacecraft. The Soviets/Russians have been doing it this way for 58 years.

    • Is the Wiki article on “Horizontal Integration Facility” something I should maybe trust?

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    • >> Is the Wiki article on “Horizontal Integration Facility” something I should maybe trust?

      Yes, that describes facilities for assembling rockets and payloads horizontally. The U.S. traditionally used vertical integration (stacking) because it allowed lighter rocket stages which couldn’t take the stress of being erected to vertical before launch. Horizontal integration saves money since most of the work can be done close to ground level without the need for scaffolding or a means to work on the rocket on the pad or to transport it vertically from the assembly facility to the pad…[Read more]

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    • Thank you. This insight is so “extra” – new SF slang, apparently – on account of now I can better appreciate the joy #2 baby will be having at some video-conferencing launch watch party he is organizing.

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